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#41
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On 5/8/2014 7:08 PM, John Fields wrote:
On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. Everyone seems very concerned about the warranty, does anyone leave a unit modified and then call for warranty service? Let me answer that for you. Of course not, you put it back to original and then ask for warranty service. Unless your mod caused the problem. Mikek |
#42
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 19:08:40 -0500, John Fields
wrote: Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. Passive repeaters, with omni antennas don't work. The problems is that the small "illumination area" (my term) of the two antennas results in a huge overall loss. Let's play with the numbers. I'll use 0dB gain for all the antennas and for the inside to outside passive repeater losses to make the math easier. Garage door opener receiver end. Sensitivity 1 uv/12dB SINAD = -107 dBm Antenna gain on receiver = 0 dB Distance to passive repeater antenna is 10 meter. Path loss at 433 Mhz = -45 dBm http://www.qsl.net/pa2ohh/jsffield.htm Inside Antenna gain passive repeater = 0 dB Loss between inside and outside antennas = 0 dB Outside antenna gain passive repeater = 0 dB Distance from outside passive repeater antenna to remote control is 10 meters. Path loss at 433 Mhz = -45 dB Antenna gain on remote control = 0 dB Transmit power (about 100 microwatts) = -10 dBm Remote control transmitter end. So... if we start out with -10 dBm of signal and have -90 dB of total path loss through the passive repeater, the signal level arriving at the receiver will be -100 dbm, which 3 dB above the receiver sensitivity. For PWM modulation and a crude demodulator, my guess(tm) is that at least 6 dB SNR is required to demodulate the data. That puts the passive repeater scheme about 3 dB short of working. However, had there been no passive repeater over the same 20 meter distance, the path loss would have been -51 dB, resulting in a -61 dBm signal level at the receiver, which is 46 dB above the receiver sensitivity and 40 dB above my guess(tm) as to the operating threshold. That should work just fine. More simply, the difference in overall path loss between this 2 hop passive repeater and a direct shot without the passive repeater is: 45 + 45 - 51 = 39 dB There are a few situations where passive repeater do work and are useful, but extending the range of a garage door opener is not one of them. However, if you want to make it work, you'll need at least a directional antenna at the receiver, pointed to inside passive repeater antenna, which should also be directional. If the approach is along a fixed path, a direction antenna for the outside antenna will also help. The total gain of these three antennas should equal the 39 dB path loss difference in order to get the same performance as a direct shot without the passive repeater. I've build passive repeaters like this for situations where any signal is better than none at all. The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, nulls, dead spots, and irate clients. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#43
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 19:08:40 -0500, John Fields
wrote: Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. Passive repeaters, with omni antennas don't work. The problems is that the small "illumination area" (my term) of the two antennas results in a huge overall loss. Let's play with the numbers. I'll use 0dB gain for all the antennas and for the inside to outside passive repeater losses to make the math easier. Garage door opener receiver end. Sensitivity 1 uv/12dB SINAD = -107 dBm Antenna gain on receiver = 0 dB Distance to passive repeater antenna is 10 meter. Path loss at 433 Mhz = -45 dBm http://www.qsl.net/pa2ohh/jsffield.htm Inside Antenna gain passive repeater = 0 dB Loss between inside and outside antennas = 0 dB Outside antenna gain passive repeater = 0 dB Distance from outside passive repeater antenna to remote control is 10 meters. Path loss at 433 Mhz = -45 dB Antenna gain on remote control = 0 dB Transmit power (about 100 microwatts) = -10 dBm Remote control transmitter end. So... if we start out with -10 dBm of signal and have -90 dB of total path loss through the passive repeater, the signal level arriving at the receiver will be -100 dbm, which 3 dB above the receiver sensitivity. For PWM modulation and a crude demodulator, my guess(tm) is that at least 6 dB SNR is required to demodulate the data. That puts the passive repeater scheme about 3 dB short of working. However, had there been no passive repeater over the same 20 meter distance, the path loss would have been -51 dB, resulting in a -61 dBm signal level at the receiver, which is 46 dB above the receiver sensitivity and 40 dB above my guess(tm) as to the operating threshold. That should work just fine. More simply, the difference in overall path loss between this 2 hop passive repeater and a direct shot without the passive repeater is: 45 + 45 - 51 = 39 dB There are a few situations where passive repeater do work and are useful, but extending the range of a garage door opener is not one of them. However, if you want to make it work, you'll need at least a directional antenna at the receiver, pointed to inside passive repeater antenna, which should also be directional. If the approach is along a fixed path, a direction antenna for the outside antenna will also help. The total gain of these three antennas should equal the 39 dB path loss difference in order to get the same performance as a direct shot without the passive repeater. I've build passive repeaters like this for situations where any signal is better than none at all. The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, nulls, dead spots, and irate clients. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#44
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"John Fields" wrote in message ... On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. You really should do the math on that idea to find out why it won't work. Also, they do not use 900 MHz for this model. |
#45
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"John Fields" wrote in message ... On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. You really should do the math on that idea to find out why it won't work. Also, they do not use 900 MHz for this model. |
#46
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 19:44:21 -0500, John Fields
wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com |
#47
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 19:44:21 -0500, John Fields
wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com |
#48
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"Jeff Liebermann" wrote in message ... On Thu, 08 May 2014 19:08:40 -0500, John Fields wrote: Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. Passive repeaters, with omni antennas don't work. The problems is that the small "illumination area" (my term) of the two antennas results in a huge overall loss. Let's play with the numbers. I'll use 0dB gain for all the antennas and for the inside to outside passive repeater losses to make the math easier. Garage door opener receiver end. Sensitivity 1 uv/12dB SINAD = -107 dBm Antenna gain on receiver = 0 dB Distance to passive repeater antenna is 10 meter. Path loss at 433 Mhz = -45 dBm http://www.qsl.net/pa2ohh/jsffield.htm Inside Antenna gain passive repeater = 0 dB Loss between inside and outside antennas = 0 dB Outside antenna gain passive repeater = 0 dB Distance from outside passive repeater antenna to remote control is 10 meters. Path loss at 433 Mhz = -45 dB Antenna gain on remote control = 0 dB Transmit power (about 100 microwatts) = -10 dBm Remote control transmitter end. So... if we start out with -10 dBm of signal and have -90 dB of total path loss through the passive repeater, the signal level arriving at the receiver will be -100 dbm, which 3 dB above the receiver sensitivity. For PWM modulation and a crude demodulator, my guess(tm) is that at least 6 dB SNR is required to demodulate the data. That puts the passive repeater scheme about 3 dB short of working. However, had there been no passive repeater over the same 20 meter distance, the path loss would have been -51 dB, resulting in a -61 dBm signal level at the receiver, which is 46 dB above the receiver sensitivity and 40 dB above my guess(tm) as to the operating threshold. That should work just fine. More simply, the difference in overall path loss between this 2 hop passive repeater and a direct shot without the passive repeater is: 45 + 45 - 51 = 39 dB There are a few situations where passive repeater do work and are useful, but extending the range of a garage door opener is not one of them. However, if you want to make it work, you'll need at least a directional antenna at the receiver, pointed to inside passive repeater antenna, which should also be directional. If the approach is along a fixed path, a direction antenna for the outside antenna will also help. The total gain of these three antennas should equal the 39 dB path loss difference in order to get the same performance as a direct shot without the passive repeater. I've build passive repeaters like this for situations where any signal is better than none at all. The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, nulls, dead spots, and irate clients. At 200 m (down the street, why he is doing this) the FSPL is 71 dB. The Tx antenna will have lots of loss buried in the car body. The Genie opener just has a short (15 inches) length of wire hanging down for its antenna. No real 400 MHz ground plane so I doubt it will be 0 dB. |
#49
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"Jeff Liebermann" wrote in message ... On Thu, 08 May 2014 19:08:40 -0500, John Fields wrote: Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. Passive repeaters, with omni antennas don't work. The problems is that the small "illumination area" (my term) of the two antennas results in a huge overall loss. Let's play with the numbers. I'll use 0dB gain for all the antennas and for the inside to outside passive repeater losses to make the math easier. Garage door opener receiver end. Sensitivity 1 uv/12dB SINAD = -107 dBm Antenna gain on receiver = 0 dB Distance to passive repeater antenna is 10 meter. Path loss at 433 Mhz = -45 dBm http://www.qsl.net/pa2ohh/jsffield.htm Inside Antenna gain passive repeater = 0 dB Loss between inside and outside antennas = 0 dB Outside antenna gain passive repeater = 0 dB Distance from outside passive repeater antenna to remote control is 10 meters. Path loss at 433 Mhz = -45 dB Antenna gain on remote control = 0 dB Transmit power (about 100 microwatts) = -10 dBm Remote control transmitter end. So... if we start out with -10 dBm of signal and have -90 dB of total path loss through the passive repeater, the signal level arriving at the receiver will be -100 dbm, which 3 dB above the receiver sensitivity. For PWM modulation and a crude demodulator, my guess(tm) is that at least 6 dB SNR is required to demodulate the data. That puts the passive repeater scheme about 3 dB short of working. However, had there been no passive repeater over the same 20 meter distance, the path loss would have been -51 dB, resulting in a -61 dBm signal level at the receiver, which is 46 dB above the receiver sensitivity and 40 dB above my guess(tm) as to the operating threshold. That should work just fine. More simply, the difference in overall path loss between this 2 hop passive repeater and a direct shot without the passive repeater is: 45 + 45 - 51 = 39 dB There are a few situations where passive repeater do work and are useful, but extending the range of a garage door opener is not one of them. However, if you want to make it work, you'll need at least a directional antenna at the receiver, pointed to inside passive repeater antenna, which should also be directional. If the approach is along a fixed path, a direction antenna for the outside antenna will also help. The total gain of these three antennas should equal the 39 dB path loss difference in order to get the same performance as a direct shot without the passive repeater. I've build passive repeaters like this for situations where any signal is better than none at all. The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, nulls, dead spots, and irate clients. At 200 m (down the street, why he is doing this) the FSPL is 71 dB. The Tx antenna will have lots of loss buried in the car body. The Genie opener just has a short (15 inches) length of wire hanging down for its antenna. No real 400 MHz ground plane so I doubt it will be 0 dB. |
#50
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 17:51:16 -0700, Jeff Liebermann
wrote: On Thu, 08 May 2014 19:08:40 -0500, John Fields wrote: Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. Passive repeaters, with omni antennas don't work. The problems is that the small "illumination area" (my term) of the two antennas results in a huge overall loss. Let's play with the numbers. I'll use 0dB gain for all the antennas and for the inside to outside passive repeater losses to make the math easier. Garage door opener receiver end. Sensitivity 1 uv/12dB SINAD = -107 dBm Antenna gain on receiver = 0 dB Distance to passive repeater antenna is 10 meter. Path loss at 433 Mhz = -45 dBm http://www.qsl.net/pa2ohh/jsffield.htm Inside Antenna gain passive repeater = 0 dB Loss between inside and outside antennas = 0 dB Outside antenna gain passive repeater = 0 dB Distance from outside passive repeater antenna to remote control is 10 meters. Path loss at 433 Mhz = -45 dB Antenna gain on remote control = 0 dB Transmit power (about 100 microwatts) = -10 dBm Remote control transmitter end. So... if we start out with -10 dBm of signal and have -90 dB of total path loss through the passive repeater, the signal level arriving at the receiver will be -100 dbm, which 3 dB above the receiver sensitivity. For PWM modulation and a crude demodulator, my guess(tm) is that at least 6 dB SNR is required to demodulate the data. That puts the passive repeater scheme about 3 dB short of working. --- A cursory look through Google finds: http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 so the 5dB gain for the pair of antennas - all the rest of your numbers staying the same - puts the scheme about 2dB long on working. Not an awful lot, but it's over the edge and for less than $20 for the antennas, in my book it's probably worth trying. --- However, had there been no passive repeater over the same 20 meter distance, the path loss would have been -51 dB, resulting in a -61 dBm signal level at the receiver, which is 46 dB above the receiver sensitivity and 40 dB above my guess(tm) as to the operating threshold. That should work just fine. More simply, the difference in overall path loss between this 2 hop passive repeater and a direct shot without the passive repeater is: 45 + 45 - 51 = 39 dB --- OK, but that garage door and all the aluminum foil around the house is a big attenuator killing what would be a direct shot. --- There are a few situations where passive repeater do work and are useful, but extending the range of a garage door opener is not one of them. However, if you want to make it work, you'll need at least a directional antenna at the receiver, pointed to inside passive repeater antenna, which should also be directional. If the approach is along a fixed path, a direction antenna for the outside antenna will also help. The total gain of these three antennas should equal the 39 dB path loss difference in order to get the same performance as a direct shot without the passive repeater. I've build passive repeaters like this for situations where any signal is better than none at all. --- Sounds just like Jim's situation. --- The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, --- And enhancement --- nulls --- and peaks --- dead spots --- and hot spots --- and irate clients. --- I don't think that'll be a problem in this instance and, anyway, it's better to have loved and lost than never to have loved at all... :-) |
#51
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 17:51:16 -0700, Jeff Liebermann
wrote: On Thu, 08 May 2014 19:08:40 -0500, John Fields wrote: Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. Passive repeaters, with omni antennas don't work. The problems is that the small "illumination area" (my term) of the two antennas results in a huge overall loss. Let's play with the numbers. I'll use 0dB gain for all the antennas and for the inside to outside passive repeater losses to make the math easier. Garage door opener receiver end. Sensitivity 1 uv/12dB SINAD = -107 dBm Antenna gain on receiver = 0 dB Distance to passive repeater antenna is 10 meter. Path loss at 433 Mhz = -45 dBm http://www.qsl.net/pa2ohh/jsffield.htm Inside Antenna gain passive repeater = 0 dB Loss between inside and outside antennas = 0 dB Outside antenna gain passive repeater = 0 dB Distance from outside passive repeater antenna to remote control is 10 meters. Path loss at 433 Mhz = -45 dB Antenna gain on remote control = 0 dB Transmit power (about 100 microwatts) = -10 dBm Remote control transmitter end. So... if we start out with -10 dBm of signal and have -90 dB of total path loss through the passive repeater, the signal level arriving at the receiver will be -100 dbm, which 3 dB above the receiver sensitivity. For PWM modulation and a crude demodulator, my guess(tm) is that at least 6 dB SNR is required to demodulate the data. That puts the passive repeater scheme about 3 dB short of working. --- A cursory look through Google finds: http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 so the 5dB gain for the pair of antennas - all the rest of your numbers staying the same - puts the scheme about 2dB long on working. Not an awful lot, but it's over the edge and for less than $20 for the antennas, in my book it's probably worth trying. --- However, had there been no passive repeater over the same 20 meter distance, the path loss would have been -51 dB, resulting in a -61 dBm signal level at the receiver, which is 46 dB above the receiver sensitivity and 40 dB above my guess(tm) as to the operating threshold. That should work just fine. More simply, the difference in overall path loss between this 2 hop passive repeater and a direct shot without the passive repeater is: 45 + 45 - 51 = 39 dB --- OK, but that garage door and all the aluminum foil around the house is a big attenuator killing what would be a direct shot. --- There are a few situations where passive repeater do work and are useful, but extending the range of a garage door opener is not one of them. However, if you want to make it work, you'll need at least a directional antenna at the receiver, pointed to inside passive repeater antenna, which should also be directional. If the approach is along a fixed path, a direction antenna for the outside antenna will also help. The total gain of these three antennas should equal the 39 dB path loss difference in order to get the same performance as a direct shot without the passive repeater. I've build passive repeaters like this for situations where any signal is better than none at all. --- Sounds just like Jim's situation. --- The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, --- And enhancement --- nulls --- and peaks --- dead spots --- and hot spots --- and irate clients. --- I don't think that'll be a problem in this instance and, anyway, it's better to have loved and lost than never to have loved at all... :-) |
#52
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 18:21:45 -0700, John Larkin
wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... |
#53
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 18:21:45 -0700, John Larkin
wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... |
#54
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"John Fields" wrote in message ... On Thu, 08 May 2014 18:21:45 -0700, John Larkin wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... It's not at 900 MHz. Whoosh whoosh... |
#55
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"John Fields" wrote in message ... On Thu, 08 May 2014 18:21:45 -0700, John Larkin wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... It's not at 900 MHz. Whoosh whoosh... |
#56
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 8 May 2014 22:07:46 -0400, "Tom Miller"
wrote: "Tom Miller" wrote in message ... "John Fields" wrote in message ... On Thu, 08 May 2014 18:21:45 -0700, John Larkin wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... It's not at 900 MHz. Whoosh whoosh... Or even 1900 MHz. Do you even think before typing? Whoosh whoosh... In a black helicopter ?:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#57
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"Tom Miller" wrote in message ... "John Fields" wrote in message ... On Thu, 08 May 2014 18:21:45 -0700, John Larkin wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... It's not at 900 MHz. Whoosh whoosh... Or even 1900 MHz. Do you even think before typing? Whoosh whoosh... |
#58
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"Tom Miller" wrote in message ... "John Fields" wrote in message ... On Thu, 08 May 2014 18:21:45 -0700, John Larkin wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... It's not at 900 MHz. Whoosh whoosh... Or even 1900 MHz. Do you even think before typing? Whoosh whoosh... |
#59
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 8 May 2014 22:04:20 -0400, "Tom Miller"
wrote: "John Fields" wrote in message .. . On Thu, 08 May 2014 18:21:45 -0700, John Larkin wrote: On Thu, 08 May 2014 19:44:21 -0500, John Fields wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' Any ideas on how I could extend that range? ...Jim Thompson --- What I'd do would be to drill a hole through the garage wall next to the door but up high, then connect a length of 50 ohm coax to a weatherproof 900MHz rubber duckie antenna with a 90 degree mounting flange/bracket and pass the coax through the hole from the outside of the garage to the inside. Next, I'd mount the rubber duckie to the outside wall with the whip oriented vertically, and weatherize the installation. Finally, I'd mount another rubber duckie on the inside wall, with the whip oriented vertically, and connect the coax. Voila! passive repeater, - probably with some gain - nice clean install, and your warranty stays intact since you haven't even touched the holy RX. John Fields Gain? --- 2.5dB over isotropic. http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 Whoosh... It's not at 900 MHz. Whoosh whoosh... --- http://en.wikipedia.org/wiki/Isotropic_radiator Whoosh whoosh whoosh. John Fields |
#60
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 8 May 2014 21:31:45 -0400, "Tom Miller"
wrote: At 200 m (down the street, why he is doing this) the FSPL is 71 dB. The Tx antenna will have lots of loss buried in the car body. The Genie opener just has a short (15 inches) length of wire hanging down for its antenna. No real 400 MHz ground plane so I doubt it will be 0 dB. Agreed. 0 dB losses and 0 dBm gains were mostly so I didn't have to reach across the desk for my calculator. I made no effort to be accurate or even realistic. I simply wanted to demonstrate the effect of putting a passive repeater in the middle of the RF path. I can change the numbers to more closely reflect reality, but the added losses due to the passive repeater will not change things very much. A 200 meter outside path will make a passive repeater even less desirable. If I leave the inside path at 10 meters, which I think is realistic for across a large garage, and use 200 meters for the distance between the car and the garage the path loss will be: Without passive repeater. 210 meter path at 433 MHz: http://www.qsl.net/pa2ohh/jsffield.htm the loss is 72 dB. With 200 meters plus the passive repeater at 10 meters, the loss is: 71.2 dB + 45.2 = 116 dB With this arrangement, the RF signal level at the receiver will be -126 dBm, which is well below the receiver operating level. That's a difference of 44 between using a passive repeater and a direct shot. Throwing in realistic antenna gains will make things even worse. Quiz: Starting with a 1/4 wave whip antenna over a large ground, how short can this antenna be cut before the gain drops substantially? http://802.11junk.com/jeffl/antennas/Monopole/index.html The numbers in the filenames are the antenna lengths in wavelengths. For example, monopole_0_125 is 0.125 wavelengths or 1/8th wavelength. I only ran 3 applicable lengths, but the gain figures should offer a clue that as long as the feed impedances are reasonably well matched, you can probably cut an antenna down to below 1/20th wavelength, and still have a fair amount of gain: wavelengths gain(dbm) 0.250 5.19 0.125 4.85 0.050 4.75 The VSWR is atrocious, but the gain is still mostly there. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#61
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 20:54:18 -0500, John Fields
wrote: A cursory look through Google finds: http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 I do wish you would use a 433 MHz or 315 Mhz rubber ducky antenna. I'll make it easy. Put a pizza platter on Jim's roof and ceiling. Add a 5/8 wave antenna with a suitable matching transformer, and I'll call it about 5 dBi gain. At 10 meters from the garage, that will probably work. At 200 meters, no way. so the 5dB gain for the pair of antennas - all the rest of your numbers staying the same - puts the scheme about 2dB long on working. Sure. Like I said. Add some gain at any of the antennas to make up for the 39 dB difference in path loss between the direct versus the passive repeater, and it will work just fine. However 2.5dB gain per antenna is not going to make up for 39 dB of loss. Granted, you can run the signal levels down to the minimum detectable signal level, and possibly make it work. However, don't use my figures for doing that. I picked 0dB losses and 0dB gain antennas simply to illustrate the large difference in path loss between the two schemes. If you want a more accurate calculation, I can grind out the numbers. I'll need some details from Jim Thomson, such as the height of the garage, the height of the garage door opener, and the size of the garage. Not an awful lot, but it's over the edge and for less than $20 for the antennas, in my book it's probably worth trying. I think differently. Using my numbers, the only way to compensate for the difference in losses is with antenna gain. Well, maybe increase the transmit power or put an RF amp in front of the receiver. OK, but that garage door and all the aluminum foil around the house is a big attenuator killing what would be a direct shot. True. However, that doesn't make much difference if the antenna is outside the shielded garage. I consider that a necessity, whether using a passive repeater or a direct shot. Sounds just like Jim's situation. No, it's not. The situations that work is where there is absolutely no signal via the direct path. The basement of an emergency center is one. Another is 4 floors down in an underground garage. Jim's shielded garage may be very lossy, but is still leaky enough that cancellation (nulls) between the incident and passive repeated signals will be a problem. The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, And enhancement Only if you're lucky. The problems with such calculations as mine is that they define the best possible conditions, where everything behaves exactly as predicted. Reality tends to suggest that this is most often not the case. Losses are never better than predicted. Power output and rx sensitivity are never up to spec. Path losses always have some extra obstructions that raise the losses. And, I haven't even thrown in Fresnel zone diffraction. There are no optimists in the RF business and antenna problems tend to be very strange: http://people.csail.mit.edu/bkph/images/theres_your_reception_problem.jpg I don't think that'll be a problem in this instance and, anyway, it's better to have loved and lost than never to have loved at all... :-) Believe me, I have loved passive repeaters since I discovered one hiking in the hills above Big Bear Lake in southern Calif. When we finally reached the top of the mountain, there was a huge billboard on top. No advertising or embellishments. Just a billboard. I discovered later that it was a passive reflector for the microwave links used by AT&T to cross the country. I thought it was cool. Somewhat later, I blundered into periscope antennas, where a 45 degree reflector in the shape of an ellipse was perched on top of a tower, with a dish antenna pointing straight up at the reflector. Again I thought it was cool. Then, I discovered that ecology and fiber optics had conspired to remove the billboards from the mountain tops. The FCC also took a dim view of the signal splatter produced by periscope antennas and effectively banned them. So much for my first love in antennas. At various times in my checkered career, I've toyed with various forms of passive repeaters, and found little in the way of success. The math shows why, but I was more than willing to ignore the calculations in the hope that they might be wrong. When Wi-Fi took hold, I immediately resurrected the idea in a 200ft fir tree, pointing one dish at the WISP (wireless ISP) and the other down to my house. As long as I didn't mind climbing the tree to realign the antenna every few weeks, it worked fairly well. I never make the same mistake twice. 5 or 10 times is more my style. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#62
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On 09/05/2014 04:24, Jeff Liebermann wrote:
On Thu, 8 May 2014 21:31:45 -0400, "Tom Miller" wrote: At 200 m (down the street, why he is doing this) the FSPL is 71 dB. The Tx antenna will have lots of loss buried in the car body. The Genie opener just has a short (15 inches) length of wire hanging down for its antenna. No real 400 MHz ground plane so I doubt it will be 0 dB. Agreed. 0 dB losses and 0 dBm gains were mostly so I didn't have to reach across the desk for my calculator. I made no effort to be accurate or even realistic. I simply wanted to demonstrate the effect of putting a passive repeater in the middle of the RF path. I can change the numbers to more closely reflect reality, but the added losses due to the passive repeater will not change things very much. A 200 meter outside path will make a passive repeater even less desirable. If I leave the inside path at 10 meters, which I think is realistic for across a large garage, and use 200 meters for the distance between the car and the garage the path loss will be: Without passive repeater. 210 meter path at 433 MHz: http://www.qsl.net/pa2ohh/jsffield.htm the loss is 72 dB. With 200 meters plus the passive repeater at 10 meters, the loss is: 71.2 dB + 45.2 = 116 dB With this arrangement, the RF signal level at the receiver will be -126 dBm, which is well below the receiver operating level. That's a difference of 44 between using a passive repeater and a direct shot. Throwing in realistic antenna gains will make things even worse. Quiz: Starting with a 1/4 wave whip antenna over a large ground, how short can this antenna be cut before the gain drops substantially? http://802.11junk.com/jeffl/antennas/Monopole/index.html The numbers in the filenames are the antenna lengths in wavelengths. For example, monopole_0_125 is 0.125 wavelengths or 1/8th wavelength. I only ran 3 applicable lengths, but the gain figures should offer a clue that as long as the feed impedances are reasonably well matched, you can probably cut an antenna down to below 1/20th wavelength, and still have a fair amount of gain: wavelengths gain(dbm) 0.250 5.19 0.125 4.85 0.050 4.75 The VSWR is atrocious, but the gain is still mostly there. What is the software model you've used here? -- Mike Perkins Video Solutions Ltd www.videosolutions.ltd.uk |
#63
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Fri, 09 May 2014 12:02:50 +0100, Mike Perkins
wrote: http://802.11junk.com/jeffl/antennas/Monopole/index.html What is the software model you've used here? 4NEC2: http://www.qsl.net/4nec2/ 4NEC2 does not have an easy way to produce presentable web pages, so I screen grabbed the JPG's using Irfanview and assembled the web page with jAlbum. I also use EZNEC: http://www.eznec.com -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#64
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"Jeff Liebermann" wrote in message ... On Fri, 09 May 2014 12:02:50 +0100, Mike Perkins wrote: http://802.11junk.com/jeffl/antennas/Monopole/index.html What is the software model you've used here? 4NEC2: http://www.qsl.net/4nec2/ 4NEC2 does not have an easy way to produce presentable web pages, so I screen grabbed the JPG's using Irfanview and assembled the web page with jAlbum. I also use EZNEC: http://www.eznec.com -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 Do you believe the numbers it is giving you? 5.19 dB for a 1/4 wave ground plane antenna? Also, gain is in dB, not dBm. Just a little nit. |
#65
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Thu, 08 May 2014 20:59:29 -0700, Jeff Liebermann
wrote: On Thu, 08 May 2014 20:54:18 -0500, John Fields wrote: A cursory look through Google finds: http://www.terra-wave.com/shop/89096...l27hveoggt6rf4 I do wish you would use a 433 MHz or 315 Mhz rubber ducky antenna. I'll make it easy. Put a pizza platter on Jim's roof and ceiling. Add a 5/8 wave antenna with a suitable matching transformer, and I'll call it about 5 dBi gain. At 10 meters from the garage, that will probably work. At 200 meters, no way. so the 5dB gain for the pair of antennas - all the rest of your numbers staying the same - puts the scheme about 2dB long on working. Sure. Like I said. Add some gain at any of the antennas to make up for the 39 dB difference in path loss between the direct versus the passive repeater, and it will work just fine. However 2.5dB gain per antenna is not going to make up for 39 dB of loss. Granted, you can run the signal levels down to the minimum detectable signal level, and possibly make it work. However, don't use my figures for doing that. I picked 0dB losses and 0dB gain antennas simply to illustrate the large difference in path loss between the two schemes. If you want a more accurate calculation, I can grind out the numbers. I'll need some details from Jim Thomson, such as the height of the garage, the height of the garage door opener, and the size of the garage. Not an awful lot, but it's over the edge and for less than $20 for the antennas, in my book it's probably worth trying. I think differently. Using my numbers, the only way to compensate for the difference in losses is with antenna gain. Well, maybe increase the transmit power or put an RF amp in front of the receiver. OK, but that garage door and all the aluminum foil around the house is a big attenuator killing what would be a direct shot. True. However, that doesn't make much difference if the antenna is outside the shielded garage. I consider that a necessity, whether using a passive repeater or a direct shot. Sounds just like Jim's situation. No, it's not. The situations that work is where there is absolutely no signal via the direct path. The basement of an emergency center is one. Another is 4 floors down in an underground garage. Jim's shielded garage may be very lossy, but is still leaky enough that cancellation (nulls) between the incident and passive repeated signals will be a problem. The catch is that if there's any signal leakage from a direct path that bypasses the passive repeater, there will be cancellation, And enhancement Only if you're lucky. The problems with such calculations as mine is that they define the best possible conditions, where everything behaves exactly as predicted. Reality tends to suggest that this is most often not the case. Losses are never better than predicted. Power output and rx sensitivity are never up to spec. Path losses always have some extra obstructions that raise the losses. And, I haven't even thrown in Fresnel zone diffraction. There are no optimists in the RF business and antenna problems tend to be very strange: http://people.csail.mit.edu/bkph/images/theres_your_reception_problem.jpg I don't think that'll be a problem in this instance and, anyway, it's better to have loved and lost than never to have loved at all... :-) Believe me, I have loved passive repeaters since I discovered one hiking in the hills above Big Bear Lake in southern Calif. When we finally reached the top of the mountain, there was a huge billboard on top. No advertising or embellishments. Just a billboard. I discovered later that it was a passive reflector for the microwave links used by AT&T to cross the country. I thought it was cool. Somewhat later, I blundered into periscope antennas, where a 45 degree reflector in the shape of an ellipse was perched on top of a tower, with a dish antenna pointing straight up at the reflector. Again I thought it was cool. Then, I discovered that ecology and fiber optics had conspired to remove the billboards from the mountain tops. The FCC also took a dim view of the signal splatter produced by periscope antennas and effectively banned them. So much for my first love in antennas. At various times in my checkered career, I've toyed with various forms of passive repeaters, and found little in the way of success. The math shows why, but I was more than willing to ignore the calculations in the hope that they might be wrong. When Wi-Fi took hold, I immediately resurrected the idea in a 200ft fir tree, pointing one dish at the WISP (wireless ISP) and the other down to my house. As long as I didn't mind climbing the tree to realign the antenna every few weeks, it worked fairly well. I never make the same mistake twice. 5 or 10 times is more my style. --- Nice. :-) Thanks, John Fields |
#66
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Fri, 9 May 2014 12:31:01 -0400, "Tom Miller"
wrote: "Jeff Liebermann" wrote in message .. . On Fri, 09 May 2014 12:02:50 +0100, Mike Perkins wrote: http://802.11junk.com/jeffl/antennas/Monopole/index.html What is the software model you've used here? 4NEC2: http://www.qsl.net/4nec2/ 4NEC2 does not have an easy way to produce presentable web pages, so I screen grabbed the JPG's using Irfanview and assembled the web page with jAlbum. I also use EZNEC: http://www.eznec.com -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 Do you believe the numbers it is giving you? 5.19 dB for a 1/4 wave ground plane antenna? Also, gain is in dB, not dBm. Just a little nit. It is not that far away, assuming perfect ground, which explains the lower lobe to reflected upwards, which would explain 3 dB of gain. The remaining 2.19 dB sounds much like the dipole gain over an isotropic radiator. So actually, we should talk about 5.19 dBi gain or actually _directivity_. For electrically small antennas, the efficiency can be much less than 100 %, thus the _gain_ would be less. |
#67
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Fri, 09 May 2014 12:02:50 +0100, Mike Perkins
wrote: On 09/05/2014 04:24, Jeff Liebermann wrote: On Thu, 8 May 2014 21:31:45 -0400, "Tom Miller" wrote: At 200 m (down the street, why he is doing this) the FSPL is 71 dB. The Tx antenna will have lots of loss buried in the car body. The Genie opener just has a short (15 inches) length of wire hanging down for its antenna. No real 400 MHz ground plane so I doubt it will be 0 dB. Agreed. 0 dB losses and 0 dBm gains were mostly so I didn't have to reach across the desk for my calculator. I made no effort to be accurate or even realistic. I simply wanted to demonstrate the effect of putting a passive repeater in the middle of the RF path. I can change the numbers to more closely reflect reality, but the added losses due to the passive repeater will not change things very much. A 200 meter outside path will make a passive repeater even less desirable. If I leave the inside path at 10 meters, which I think is realistic for across a large garage, and use 200 meters for the distance between the car and the garage the path loss will be: Without passive repeater. 210 meter path at 433 MHz: http://www.qsl.net/pa2ohh/jsffield.htm the loss is 72 dB. With 200 meters plus the passive repeater at 10 meters, the loss is: 71.2 dB + 45.2 = 116 dB With this arrangement, the RF signal level at the receiver will be -126 dBm, which is well below the receiver operating level. That's a difference of 44 between using a passive repeater and a direct shot. Throwing in realistic antenna gains will make things even worse. Quiz: Starting with a 1/4 wave whip antenna over a large ground, how short can this antenna be cut before the gain drops substantially? http://802.11junk.com/jeffl/antennas/Monopole/index.html The numbers in the filenames are the antenna lengths in wavelengths. For example, monopole_0_125 is 0.125 wavelengths or 1/8th wavelength. I only ran 3 applicable lengths, but the gain figures should offer a clue that as long as the feed impedances are reasonably well matched, you can probably cut an antenna down to below 1/20th wavelength, and still have a fair amount of gain: wavelengths gain(dbm) 0.250 5.19 0.125 4.85 0.050 4.75 The VSWR is atrocious, but the gain is still mostly there. What is the software model you've used here? When the physical dimensions of an antenna are reduced, the antenna effective capture area and hence the obtainable receiver power drops much slower. Of course, there must be a proper match between the (reactive) antenna and the receiver. |
#68
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Fri, 9 May 2014 12:31:01 -0400, "Tom Miller"
wrote: "Jeff Liebermann" wrote in message .. . On Fri, 09 May 2014 12:02:50 +0100, Mike Perkins wrote: http://802.11junk.com/jeffl/antennas/Monopole/index.html Do you believe the numbers it is giving you? 5.19 dB for a 1/4 wave ground plane antenna? Also, gain is in dB, not dBm. Just a little nit. Sorry about the dB and dBm mixup. My sloppiness. Thanks. Yes, I believe the gain figures. However, it doesn't matter because my point was that the CHANGE in gain with reduced antenna length is minimal. I've seen that in bench and field tests, so I know that works. The catch is that the antenna has to be impedance matched, which becomes increasingly more difficult and lossy as the antenna becomes shorter. In general, unless I hit one of the limitations of NEC2, the patterns and gains of the models are fairly accurate. For this monopole, the added gain comes from reflections off the ground plane. The situation is similar to a mobile HF antenna, where the length of the antenna is considerably shorter than 1/4 wavelength. As long as the antenna is reasonably well matched and the matching losses are included in the calculations, then a short antenna can work almost as well as a real 1/4 antenna. However, reality is never as good as the models predict. In this case, I'm using an infinite perfect ground. I have yet to find one of those outside of an antenna range. The matching losses for the shortened antennas will add more losses. At best, the 5.19dB gain will be a best case maximum, with reality being somewhat less. You can sorta see the effects of height above ground in: http://802.11junk.com/jeffl/antennas/vertical-dipole/index.html http://802.11junk.com/jeffl/antennas/vertical-dipole/slides/animated-v-dipole.html The animation was originally intended to show the effect of antenna height on the pattern, but it also shows the changes in gain. Closest to the ground, it shows 5.24 dB gain. Highest shows 7.08 dB. Both are much larger than the traditional 2.18 dB gain of a free space dipole. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#70
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Fri, 09 May 2014 10:50:58 -0700, Jeff Liebermann
wrote: On Fri, 9 May 2014 12:31:01 -0400, "Tom Miller" wrote: "Jeff Liebermann" wrote in message . .. On Fri, 09 May 2014 12:02:50 +0100, Mike Perkins wrote: http://802.11junk.com/jeffl/antennas/Monopole/index.html Do you believe the numbers it is giving you? 5.19 dB for a 1/4 wave ground plane antenna? Also, gain is in dB, not dBm. Just a little nit. Sorry about the dB and dBm mixup. My sloppiness. Thanks. Yes, I believe the gain figures. However, it doesn't matter because my point was that the CHANGE in gain with reduced antenna length is minimal. I've seen that in bench and field tests, so I know that works. The catch is that the antenna has to be impedance matched, which becomes increasingly more difficult and lossy as the antenna becomes shorter. In general, unless I hit one of the limitations of NEC2, the patterns and gains of the models are fairly accurate. For this monopole, the added gain comes from reflections off the ground plane. The situation is similar to a mobile HF antenna, where the length of the antenna is considerably shorter than 1/4 wavelength. As long as the antenna is reasonably well matched and the matching losses are included in the calculations, then a short antenna can work almost as well as a real 1/4 antenna. However, reality is never as good as the models predict. In this case, I'm using an infinite perfect ground. I have yet to find one of those outside of an antenna range. The matching losses for the shortened antennas will add more losses. At best, the 5.19dB gain will be a best case maximum, with reality being somewhat less. You can sorta see the effects of height above ground in: http://802.11junk.com/jeffl/antennas/vertical-dipole/index.html http://802.11junk.com/jeffl/antennas/vertical-dipole/slides/animated-v-dipole.html The animation was originally intended to show the effect of antenna height on the pattern, but it also shows the changes in gain. Closest to the ground, it shows 5.24 dB gain. Highest shows 7.08 dB. Both are much larger than the traditional 2.18 dB gain of a free space dipole. Suppose I simply made a dipole half inside and half outside? Would that improve my reception? ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#71
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
"Jim Thompson" wrote in message ... On Fri, 09 May 2014 10:50:58 -0700, Jeff Liebermann wrote: On Fri, 9 May 2014 12:31:01 -0400, "Tom Miller" wrote: "Jeff Liebermann" wrote in message ... On Fri, 09 May 2014 12:02:50 +0100, Mike Perkins wrote: http://802.11junk.com/jeffl/antennas/Monopole/index.html Do you believe the numbers it is giving you? 5.19 dB for a 1/4 wave ground plane antenna? Also, gain is in dB, not dBm. Just a little nit. Sorry about the dB and dBm mixup. My sloppiness. Thanks. Yes, I believe the gain figures. However, it doesn't matter because my point was that the CHANGE in gain with reduced antenna length is minimal. I've seen that in bench and field tests, so I know that works. The catch is that the antenna has to be impedance matched, which becomes increasingly more difficult and lossy as the antenna becomes shorter. In general, unless I hit one of the limitations of NEC2, the patterns and gains of the models are fairly accurate. For this monopole, the added gain comes from reflections off the ground plane. The situation is similar to a mobile HF antenna, where the length of the antenna is considerably shorter than 1/4 wavelength. As long as the antenna is reasonably well matched and the matching losses are included in the calculations, then a short antenna can work almost as well as a real 1/4 antenna. However, reality is never as good as the models predict. In this case, I'm using an infinite perfect ground. I have yet to find one of those outside of an antenna range. The matching losses for the shortened antennas will add more losses. At best, the 5.19dB gain will be a best case maximum, with reality being somewhat less. You can sorta see the effects of height above ground in: http://802.11junk.com/jeffl/antennas/vertical-dipole/index.html http://802.11junk.com/jeffl/antennas/vertical-dipole/slides/animated-v-dipole.html The animation was originally intended to show the effect of antenna height on the pattern, but it also shows the changes in gain. Closest to the ground, it shows 5.24 dB gain. Highest shows 7.08 dB. Both are much larger than the traditional 2.18 dB gain of a free space dipole. Suppose I simply made a dipole half inside and half outside? Would that improve my reception? ...Jim Thompson -- No. Well, maybe. Hell, why don't you just extend the existing wire antenna to the outside and treat it like a long wire antenna. It might work. Or it might make the receiver oscillate . |
#72
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Garage Door Opener Range.
On Fri, 09 May 2014 11:21:13 -0700, Jeff Liebermann
wrote: On Fri, 09 May 2014 20:41:15 +0300, wrote: Do you believe the numbers it is giving you? 5.19 dB for a 1/4 wave ground plane antenna? Also, gain is in dB, not dBm. Just a little nit. It is not that far away, assuming perfect ground, which explains the lower lobe to reflected upwards, which would explain 3 dB of gain. The remaining 2.19 dB sounds much like the dipole gain over an isotropic radiator. So actually, we should talk about 5.19 dBi gain or actually _directivity_. Good explanation and you're correct about the directivity. Having gain in the wrong direction isn't very useful. In the case of the shortened monopole, the peak gain is in roughly the correct direction needed to be useful, so it's not an issue. However, other antenna configurations can cause problems. For example, here's an animated GIF of a common discone antenna. Up to about 400 MHz, the major lobe (i.e. maximum gain) is roughly horizontal, making the antenna quite useable. However, between 400 and 1000 MHz, most of the RF goes straight up. There's little RF left at the horizon, where it's needed. Such an antenna might be good for listening to airplanes, but not terrestrial stations. For electrically small antennas, the efficiency can be much less than 100 %, thus the _gain_ would be less. The radiation efficiency and internal losses are included in the gain calculation. For example, if I made the antenna from lossy material, it would show up as a loss in gain. However, for a fairly close to ideal antenna, the radiation efficiency barely changes. wavelengths gain Efficiency Radiation (db) Efficiency 0.250 5.19 100% 99.93% 0.125 4.85 100% 99.66% 0.050 4.75 100% 99.09% Again, the problem is matching the impedance of the shortened antenna. The losses are not in the antenna. They're in the matching circuit. wavelengths gain(db) VSWR (50ohms) 0.250 5.19 1.74:1 0.125 4.85 158:1 0.050 4.75 5954:1 Most of this VSWR is due to the fact that the small antenna has a high (capacitive) reactance. Tuning it out with a loading coil, you only have a smallish resistance mismatch and hence much lower VSWR. The 0.050 wavelength monopole shows a feed impedance of 1.52-j707 which is going to be verrrrrry difficult to match efficiently to 50 ohms. Got a 500:1 transformer handy? You tune out the capacitive -j707 ohms with a loading coil +j707 ohms and you only have to worry about the resistive 1.52 ohms. To match this to a 50 ohm input, the impedance ratio would be 1.52:50 or 1:33 or less than 1:6 turns ratio. A few cm long "rubber duck" (normal mode helix) is a reasonably efficient antenna for 433 MHz. |
#73
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
wrote in message ... On Fri, 09 May 2014 11:21:13 -0700, Jeff Liebermann wrote: On Fri, 09 May 2014 20:41:15 +0300, wrote: Do you believe the numbers it is giving you? 5.19 dB for a 1/4 wave ground plane antenna? Also, gain is in dB, not dBm. Just a little nit. It is not that far away, assuming perfect ground, which explains the lower lobe to reflected upwards, which would explain 3 dB of gain. The remaining 2.19 dB sounds much like the dipole gain over an isotropic radiator. So actually, we should talk about 5.19 dBi gain or actually _directivity_. Good explanation and you're correct about the directivity. Having gain in the wrong direction isn't very useful. In the case of the shortened monopole, the peak gain is in roughly the correct direction needed to be useful, so it's not an issue. However, other antenna configurations can cause problems. For example, here's an animated GIF of a common discone antenna. Up to about 400 MHz, the major lobe (i.e. maximum gain) is roughly horizontal, making the antenna quite useable. However, between 400 and 1000 MHz, most of the RF goes straight up. There's little RF left at the horizon, where it's needed. Such an antenna might be good for listening to airplanes, but not terrestrial stations. For electrically small antennas, the efficiency can be much less than 100 %, thus the _gain_ would be less. The radiation efficiency and internal losses are included in the gain calculation. For example, if I made the antenna from lossy material, it would show up as a loss in gain. However, for a fairly close to ideal antenna, the radiation efficiency barely changes. wavelengths gain Efficiency Radiation (db) Efficiency 0.250 5.19 100% 99.93% 0.125 4.85 100% 99.66% 0.050 4.75 100% 99.09% Again, the problem is matching the impedance of the shortened antenna. The losses are not in the antenna. They're in the matching circuit. wavelengths gain(db) VSWR (50ohms) 0.250 5.19 1.74:1 0.125 4.85 158:1 0.050 4.75 5954:1 Most of this VSWR is due to the fact that the small antenna has a high (capacitive) reactance. Tuning it out with a loading coil, you only have a smallish resistance mismatch and hence much lower VSWR. The 0.050 wavelength monopole shows a feed impedance of 1.52-j707 which is going to be verrrrrry difficult to match efficiently to 50 ohms. Got a 500:1 transformer handy? You tune out the capacitive -j707 ohms with a loading coil +j707 ohms and you only have to worry about the resistive 1.52 ohms. To match this to a 50 ohm input, the impedance ratio would be 1.52:50 or 1:33 or less than 1:6 turns ratio. A few cm long "rubber duck" (normal mode helix) is a reasonably efficient antenna for 433 MHz. But only for certain values of "reasonably" . |
#74
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On 5/9/2014 1:25 PM, Jim Thompson wrote:
Suppose I simply made a dipole half inside and half outside? Would that improve my reception? ...Jim Thompson OK Jim, What is the model # of your opener, Let's find out what the output circuit looks like. Here's a few, http://tinyurl.com/mwcbr2o Mike --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#75
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Wed, 07 May 2014 19:26:23 -0700, Jeff Liebermann
wrote: On Wed, 07 May 2014 13:27:29 -0700, Jim Thompson wrote: This new, very well-insulated, foil-backed, house has one drawback... the garage door opener range with the garage door closed is only about 20' I assume the garage door is insulated with foil backed foam or fiberglass. Therefore, RF through the garage door is a difficult path. Door is a sheet-metal sandwich with the insulation between the two metal panels. Walls are foil-backed exterior sheathing plus foil-backed drywall inside. First, try a simple experiment. Open the garage door wide and test the range of your unspecified model garage door opener radio. If you get normal ranges (200ft or more), then the problem is the garage door shielding. However, if the range is the same, the tuning on either the transmitter or receiver is off frequency. Dramatic range improvement. [snip] How about this... Drill hole in door, fit water-tight thru-hole BNC connector, attach rubber ducky antennas to each side. Would that be enough of a "window"? ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#76
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Garage Door Opener Range.
On Fri, 09 May 2014 15:38:43 -0500, amdx wrote:
On 5/9/2014 1:25 PM, Jim Thompson wrote: Suppose I simply made a dipole half inside and half outside? Would that improve my reception? ...Jim Thompson OK Jim, What is the model # of your opener, Let's find out what the output circuit looks like. Here's a few, http://tinyurl.com/mwcbr2o Mike Genie Model 2024 Can you simply buy a 433MHz receiver that has a relay output? ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#77
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On Fri, 09 May 2014 11:25:30 -0700, Jim Thompson
wrote: Suppose I simply made a dipole half inside and half outside? Would that improve my reception? ...Jim Thompson Well, it has half a chance of working, and half a chance of making things worse. It depends on which side of the dipole you poke through the wall. Half-baked is usually the result of half-way solutions and half-ass kludges. The reason I can only offer half a reply is that I have not seen anyone build a working antenna like that, which should be a clue as to how well it might work. If you're going to drill a hole in the wall, you might as well put the entire antenna outside. However, if you insist on doing it wrong, just make sure you put the half of the dipole that goes to the coax center conductor outside the garage, and the grounded half of the dipole inside the garage. With foil backed insulation in the wall acting as a ground plane, no RF will radiate from the grounded half of the dipole, giving you a better than half-way possibility of making this technical abomination work. 1/4 wavelength at 433 MHz is about 17.5 cm. Incidentally, the problem with attaching a bigger/better/outside antenna is that it MIGHT detune the receiver. If it's a crude TRF (Tuned RF) receiver, where all the selectivity is one tuned circuit connected directly to the antenna, any changes in antenna configuration is going to create a problem. As Mike K suggested, you'll need to look at the schematic to see if there's any isolation between the antenna and the tuning. Beware of engineers bearing screwdrivers (and tuning tools). -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#78
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Garage Door Opener Range.
On Fri, 09 May 2014 13:49:47 -0700, Jim Thompson
wrote: Genie Model 2024 Can you simply buy a 433MHz receiver that has a relay output? ...Jim Thompson They're all over eBay in many different configurations. www.ebay.com/sch/i.html?_nkw=wireless+remote+switch The problem will be getting one that is compatible with your cars Homelink remote. That means you'll need to buy both the receiver and transmitter because the transmitter is needed to program the Homelink thing. However, if you're not going to use Homelink, then it's not an issue. Also, methinks we might be wrong about the frequency. The Genie 2024 runs on 390 MHz or possibly 315 MHz frequency. Genie got into problems in areas where the military was using 390 MHz for something. I'm not sure as I couldn't find any specific references. I could lookup what it does by the FCC ID number, or you could just hang a frequency counter near the trasmitter and see what frequency the remote belches. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#79
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad,sci.electronics.basics
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Garage Door Opener Range.
On 5/9/2014 3:49 PM, Jim Thompson wrote:
On Fri, 09 May 2014 15:38:43 -0500, amdx wrote: On 5/9/2014 1:25 PM, Jim Thompson wrote: Suppose I simply made a dipole half inside and half outside? Would that improve my reception? ...Jim Thompson OK Jim, What is the model # of your opener, Let's find out what the output circuit looks like. Here's a few, http://tinyurl.com/mwcbr2o Mike Genie Model 2024 Can you simply buy a 433MHz receiver that has a relay output? ...Jim Thompson Looks like about 9 wires to move the control circuit board, includes the receiver, outside. http://lib.store.yahoo.net/lib/yhst-...ion-manual.pdf Looks pretty simple to remove, pull it out and inspect, maybe draw a schematic. I got that pdf from here http://www.northshorecommercialdoor....adoop37co.html I didn't find a schematic. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#80
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Garage Door Opener Range.
On Fri, 09 May 2014 13:57:40 -0700, Jeff Liebermann
wrote: [snip] Beware of engineers bearing screwdrivers (and tuning tools). I have a whole set of tuning tools, in their original pocket protector. (I grew up in a Radio/TV repair shop in the late 50's, when there were IF cans aplenty :-) ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
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