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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Antenna rotator question
Customer wants a complete TV antenna with a rotor installed. I used
to do a lot of these so that's no problem. However the catch is that depending on where they feel like hanging out he wants to control the rotor from two different levels of the house. I've never tried to do this before. Someone else suggested that I install a control wire to the two locations and have them move the rotor between the two. I know that channel Master makes a unit with an IR remote but I would need an RF based remote to go between floors. And I'm not a big fan of Channel Master anyway. Are there any RF based solutions for this? And is the equipment consumer or commercial grade? Also back in the day I used to install Alliance rotors exclusively. They were a real quality product and I never got married to one of them. I know that Alliance has been gone for awhile now but is it true that the only ones that are now available are the crappy Chinese Philips rotors with the plastic gears that break in a windstorm? Is it even possible to buy a good quality rotor, (besides a really expensive Ham job) anymore? Lenny |
#2
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Antenna rotator question
On Thu, 27 Apr 2017 07:12:12 -0700 (PDT),
wrote: Customer wants a complete TV antenna with a rotor installed. I used to do a lot of these so that's no problem. However the catch is that depending on where they feel like hanging out he wants to control the rotor from two different levels of the house. Many rotators now have IR remote controls. For example: https://www.channelmaster.com/TV_Antenna_Rotator_p/cm-9521a.htm https://www.google.com/search?tbm=isch&q=remote+control+antenna+rotator Put and IR repeater between floors, buy a few spare remote controls, and you're done. https://www.google.com/search?q=ir+repeater&tbm=isch If you want quality, you'll probably end up with a ham radio type of rotator, for plenty more dollars. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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Antenna rotator question
Lenny:
Contact me directly, if you want to see pics of an outdoor eve install HD-8200U that isn't going anywhere. The antenna's are larger these days. Although I used an Eagle Aspen ROTR-100 and a bearing that both aren't available anymore, I'm really happy with the install. I didn't quite finish the install in terms of the minor details. The Rotor has a North position and you have to decide if your going to magnetic or real north so, I'm not calibrated yet. I put the rotor on top of a stainless split collar,so the rotor can be rotated after the fact I used Black oxide collars for temporary aides to install the antenna. All U-bolts are stainless. The guys are non-metalic and made of Phillystran and the hardware (like turnbuckles) is mostly 316 Stainless There are two types of gold annodizing and one is really bad. Two things that I would do differently a Use a fiberglass mast on the antenna side of things and powder coat a couple of the clamps on the rotor. You MUST use anti-seize for the stainless bolts. I used a small piece of siameze RG-6 satellite wire from the antenna to inside. The Eagle Aspen controls the rotor via Coax. I chose not to put the antenna on the same coax. The Aspen rotates like 460 degrees, so it prevents having to go all the way around at times. There is also 99 presets. Enough for every channel. So, that's what I have to do: Orient properly so TVfool agrees and set the presets to the channels. I want to do an an antenna combine with a single channel antenna and get a custom combiner made and installed. An IR to RF repeater works fine. There are lots of ways to do multi IR including over Ethernet. The "bad thing" about this rotor is that the displayed position is the "desired position", not the current position unless the motor is stopped. But this particular unavailable rotor has an index so it will never get out of sync. |
#4
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Antenna rotator question
On Thursday, April 27, 2017 at 7:12:18 AM UTC-7, wrote:
Customer wants a complete TV antenna with a rotor installed. I used to do a lot of these so that's no problem. However the catch is that depending on where they feel like hanging out he wants to control the rotor from two different levels of the house. I've never tried to do this before. Someone else suggested that I install a control wire to the two locations and have them move the rotor between the two. I know that channel Master makes a unit with an IR remote but I would need an RF based remote to go between floors. And I'm not a big fan of Channel Master anyway. Are there any RF based solutions for this? And is the equipment consumer or commercial grade? Also back in the day I used to install Alliance rotors exclusively. They were a real quality product and I never got married to one of them. I know that Alliance has been gone for awhile now but is it true that the only ones that are now available are the crappy Chinese Philips rotors with the plastic gears that break in a windstorm? Is it even possible to buy a good quality rotor, (besides a really expensive Ham job) anymore? Lenny Nobody using a DVR? Changing the antenna while in record ruins the capture. Home many locations are they trying to receive? G² |
#5
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Antenna rotator question
On Sat, 29 Apr 2017 11:41:51 -0700 (PDT), wrote:
Nobody using a DVR? Changing the antenna while in record ruins the capture. Home many locations are they trying to receive? G² Rotating or changing the antenna while receiving a program is only required if the signal is lousy and the user is trying to improve it. No need to rotate the antenna if the signal quality is good. If they were recording a lousy quality signal, I would think that rotating the antenna might improve the situation rather than ruining the capture. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#6
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Antenna rotator question
On Saturday, April 29, 2017 at 12:28:50 PM UTC-7, Jeff Liebermann wrote:
On Sat, 29 Apr 2017 11:41:51 -0700 (PDT), wrote: Nobody using a DVR? Changing the antenna while in record ruins the capture. Home many locations are they trying to receive? G² Rotating or changing the antenna while receiving a program is only required if the signal is lousy and the user is trying to improve it. No need to rotate the antenna if the signal quality is good. If they were recording a lousy quality signal, I would think that rotating the antenna might improve the situation rather than ruining the capture. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 When I had an antenna with a rotator many years ago it was because I was about 40 miles out from 2 different cities about 140 degrees difference. For Milwaukee the antenna aimed ENE but for Madison it needed WNW. If I was attempting to record one city and forgot and changed to the other it would have ruined the recording. Of course those were the analog days. DTV is both better and worse. My point was he might be able to use multiple antennas with diplexers and get one overall feed that could be treated like the cable company - all channels available all the time with no adjusting. G² |
#8
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Antenna rotator question
On Monday, May 1, 2017 at 8:45:45 AM UTC-7, Jeff Liebermann wrote:
On Mon, 1 May 2017 01:42:17 -0700 (PDT), wrote: My point was he might be able to use multiple antennas with diplexers and get one overall feed that could be treated like the cable company - all channels available all the time with no adjusting. G² Nope. A few problems: 1. A diplexer splits the frequencies between VHF and UHF channels. If one antenna is VHF and the other is UHF, it will work, but only if the stations in one direction are all VHF and the other direction are UHF. Methinks that's unlikely to happen. 2. If you replace the diplexer with a combiner/splitter, you theoretically can get both VHF and UHF signals from both antennas at the same time without switching. I think that's what you're suggesting. However, that doesn't work because the same signals are picked up by both antenna at the same time. If the signal are in phase, then the signals combine and you get good reception. If they're 180 degrees out of phase, you get cancellation and no signal. However, that's an over-simplification. What really happens is that the signal is 6 MHz wide and the phase cancellation varies with frequency. Some of the 6 MHz wide frequency range gets added, but other frequencies in this range get cancelled. The result is a very rocky and erratic frequency response which makes an ugly mess of the signal. Bad idea. 3. You can make it work with two antennas in two directions using a coax switch. Only one antenna is connected at a time so there is no interaction. You might need two coax cables from the mast to the TV where the switch is located. Or, you can setup a remote antenna switch. Or, you can setup a cross-over switch and two receivers, where you can record on one receiver/antenna combination, while viewing on the other. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 It's not a diplexer but these guys claim it can be done without a rotator. http://downloads.channelmaster.com/S...spec+sheet.pdf I presume they know what they're doing. G² |
#9
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Antenna rotator question
On Mon, 1 May 2017 20:52:04 -0700 (PDT), wrote:
On Monday, May 1, 2017 at 8:45:45 AM UTC-7, Jeff Liebermann wrote: On Mon, 1 May 2017 01:42:17 -0700 (PDT), wrote: My point was he might be able to use multiple antennas with diplexers and get one overall feed that could be treated like the cable company - all channels available all the time with no adjusting. G² Nope. A few problems: 1. A diplexer splits the frequencies between VHF and UHF channels. If one antenna is VHF and the other is UHF, it will work, but only if the stations in one direction are all VHF and the other direction are UHF. Methinks that's unlikely to happen. 2. If you replace the diplexer with a combiner/splitter, you theoretically can get both VHF and UHF signals from both antennas at the same time without switching. I think that's what you're suggesting. However, that doesn't work because the same signals are picked up by both antenna at the same time. If the signal are in phase, then the signals combine and you get good reception. If they're 180 degrees out of phase, you get cancellation and no signal. However, that's an over-simplification. What really happens is that the signal is 6 MHz wide and the phase cancellation varies with frequency. Some of the 6 MHz wide frequency range gets added, but other frequencies in this range get cancelled. The result is a very rocky and erratic frequency response which makes an ugly mess of the signal. Bad idea. 3. You can make it work with two antennas in two directions using a coax switch. Only one antenna is connected at a time so there is no interaction. You might need two coax cables from the mast to the TV where the switch is located. Or, you can setup a remote antenna switch. Or, you can setup a cross-over switch and two receivers, where you can record on one receiver/antenna combination, while viewing on the other. It's not a diplexer but these guys claim it can be done without a rotator. http://downloads.channelmaster.com/S...spec+sheet.pdf I presume they know what they're doing. G² Amazing. From the specs, it looks like there's a simple passive splitter/combiner inside the box. $39 is quite a bit to pay for a $2 combiner. When I tried the same thing, I ran into problems with antenna interaction as I previously described. It was easy enough to demonstrate the problem to the customer. I disconnected and terminated one port on the combiner. The picture quality dramatically improved. I repeated the exercise on the other port and had the same effect with stations on the other antenna. I also ran into one installation that had three antennas (two UHF only, and one VHF/UHF). I again could demonstrate that it worked better with just one antenna at a time. However, the customer did not want to run additional coax cables to his TV, and I couldn't find an affordable 3 or 4 port remote antenna relay. So, I built one using magnetically latched relays. It didn't look very good at the high channels when swept, but the FCC saved me by auctioning off the 700MHz channels. I suspect that a passive combiner might work if the two antennas were isolated from each other and positioned so that the antenna side lobes are not pointed in the direction of the "wrong" station. Looking at typical TV antenna patterns: http://www.hdtvprimer.com/ANTENNAS/comparing.html I think it could be done if the antennas were 90 degrees from each other. Of course, you're welcome to verify my analysis and tests. It's easy enough to do with a $2 combiner. I would be interested in your results. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#10
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Antenna rotator question
On Tue, 2 May 2017 07:01:32 -0700, Taxed and Spent
wrote: On 5/2/2017 6:36 AM, Jeff Liebermann wrote: Amazing. From the specs, it looks like there's a simple passive splitter/combiner inside the box. $39 is quite a bit to pay for a $2 combiner. it includes a bandpass filter, although apparently Channel Master wants to keep that a secret! from http://www.warrenelectronics.com/ant...Jointennas.htm Thanks for the details on the device. As you've noticed, there is much more going on behind the curtain. Under the heading on the above page: "(For blocking or passing a single channel)" "JoinTennas are NON-RETURNABLE! Limited to stock on hand - no back-orders!" There seems to be more than one model. In the "Antenna Coupler Typical Applications" on the right of the page, the 3 examples show some of the part numbers to be: Model 0578, Model 0585-2, Model 0576, and Model 0579 The multiple models, combined with the non-returnable ordering suggests that this is a custom device, tuned to frequency. The chart at the bottom of the page shows only a few UHF channels available. UHF Channels Avail. Model* 17, 18, 19 0585-1 53, 54, 55, 57, 58 0585-2 which is odd as other model numbers are mentioned under "Antenna Coupler Typical Applications". The limited channels may be only what the dealer stocks for his local channels. The filter must be rather wide as the warning suggests: "Note: There is significant attenuation on either side of the channel the JoinTenna is tuned for. We do not recommend using a JoinTenna if you are trying to receive a channel adjacent to your specified channel." None of this appears on the product page, data sheet, or installation manual: https://www.channelmaster.com/JOINtenna_p/cm-0500.htm I like the first users comments: "Having a rotating antenna was not the solution because with today's digital tuners, every time you rotate the Antenna, you must rescan your channels." I guess he doesn't know how to manually add channels. The Channel Master JoinTenna is perfect for those situations when you need to add a second antenna to pick up a broadcast station in another direction but don't wish to use a single antenna and rotator. The JoinTenna blocks all frequencies but the one it is tuned for, eliminating the ghosting and reflection that can happen when you connect two antennas together. With digital TV, one does not see ghosting or reflections on the screen. The modern term is "multipath". http://www.hdtvprimer.com/ANTENNAS/glossaryG.html#multipath http://www.hdtvprimer.com/ANTENNAS/siting.html See section under "Skyline Multi-path". If it blocks everything except the channel to which it's tuned, it must contain a BPF (bandpass filter) which adds some loss. The -2dB loss specified seems rather optimistic. The splitter/combiner typically has -1dB loss. A single channel BPF would have somewhat more than -1dB. My guess(tm) is the loss through the device is somewhat more than -2dB. There might also be a corresponding notch filter on the other port, also with some loss. Seems like this device is a usable solution if: 1. One antenna is intended to only receive one distant station. 2. The signal strengths of most stations are strong to overcome the losses. I think it fair to suggest that Channel Master would not have gone though all the trouble of installing filter(s) if there was no problem with interaction between antennas using a combiner. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#11
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Antenna rotator question
On 03/05/17 02:11, Jeff Liebermann wrote:
On Tue, 2 May 2017 07:01:32 -0700, Taxed and Spent wrote: On 5/2/2017 6:36 AM, Jeff Liebermann wrote: Amazing. From the specs, it looks like there's a simple passive splitter/combiner inside the box. $39 is quite a bit to pay for a $2 combiner. it includes a bandpass filter, although apparently Channel Master wants to keep that a secret! from http://www.warrenelectronics.com/ant...Jointennas.htm Thanks for the details on the device. As you've noticed, there is much more going on behind the curtain. Under the heading on the above page: "(For blocking or passing a single channel)" "JoinTennas are NON-RETURNABLE! Limited to stock on hand - no back-orders!" There seems to be more than one model. In the "Antenna Coupler Typical Applications" on the right of the page, the 3 examples show some of the part numbers to be: Model 0578, Model 0585-2, Model 0576, and Model 0579 The multiple models, combined with the non-returnable ordering suggests that this is a custom device, tuned to frequency. The chart at the bottom of the page shows only a few UHF channels available. UHF Channels Avail. Model* 17, 18, 19 0585-1 53, 54, 55, 57, 58 0585-2 which is odd as other model numbers are mentioned under "Antenna Coupler Typical Applications". The limited channels may be only what the dealer stocks for his local channels. The filter must be rather wide as the warning suggests: "Note: There is significant attenuation on either side of the channel the JoinTenna is tuned for. We do not recommend using a JoinTenna if you are trying to receive a channel adjacent to your specified channel." None of this appears on the product page, data sheet, or installation manual: https://www.channelmaster.com/JOINtenna_p/cm-0500.htm I like the first users comments: "Having a rotating antenna was not the solution because with today's digital tuners, every time you rotate the Antenna, you must rescan your channels." I guess he doesn't know how to manually add channels. The Channel Master JoinTenna is perfect for those situations when you need to add a second antenna to pick up a broadcast station in another direction but don't wish to use a single antenna and rotator. The JoinTenna blocks all frequencies but the one it is tuned for, eliminating the ghosting and reflection that can happen when you connect two antennas together. With digital TV, one does not see ghosting or reflections on the screen. The modern term is "multipath". http://www.hdtvprimer.com/ANTENNAS/glossaryG.html#multipath http://www.hdtvprimer.com/ANTENNAS/siting.html See section under "Skyline Multi-path". If it blocks everything except the channel to which it's tuned, it must contain a BPF (bandpass filter) which adds some loss. The -2dB loss specified seems rather optimistic. The splitter/combiner typically has -1dB loss. A single channel BPF would have somewhat more than -1dB. My guess(tm) is the loss through the device is somewhat more than -2dB. There might also be a corresponding notch filter on the other port, also with some loss. Seems like this device is a usable solution if: 1. One antenna is intended to only receive one distant station. 2. The signal strengths of most stations are strong to overcome the losses. I think it fair to suggest that Channel Master would not have gone though all the trouble of installing filter(s) if there was no problem with interaction between antennas using a combiner. It seems as though it should be straightforward to feed power up the co-ax (ala masthead amplifiers) to drive a pair of isolation amps/buffer before a combiner. That could give you a lot more isolation, without needing to go to relays. Clifford Heath. |
#12
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Antenna rotator question
I like the first users comments:
"Having a rotating antenna was not the solution because with today's digital tuners, every time you rotate the Antenna, you must rescan your channels." I guess he doesn't know how to manually add channels. That's not as far-fetched as you would think. with current Samsung so called "Smart TV's" it's not possible to add a channel. I have confirmation from Samsung. USUALLY you can use the remote to select the physical channel and the TV will tune to the first virtual channel on that frequency. This is the preferred way the US government would like it to work. Channel up/down will then tune the sub-channels. I don;t yet have confirmation that an unscanned channel works that way, but I think it will. I have a TV tuner that will not work that way at all. It reports the actual center frequency in MHz of the scanned channels, not the physical channel, but you need the physical channel to add a single channel. You basically "scan" the physical channel and add. This "stupid" $1000 tuner won;t even update the display when entering a channel digit. The on-screen display shows the remote entered digit. The display on the tuner does not. A CECB I have allows one to add "scanned" channels to the existing scan. |
#13
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Antenna rotator question
Incidently,
The CECB reports signal strength in 0 to 100 arbitrary units. The "Dumb" Samsung TV just reports s/n ratio The $1000 tuner reports both s/n and signal strength in real units. |
#14
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Antenna rotator question
On Wed, 3 May 2017 07:47:12 +1000, Clifford Heath
wrote: It seems as though it should be straightforward to feed power up the co-ax (ala masthead amplifiers) to drive a pair of isolation amps/buffer before a combiner. That could give you a lot more isolation, without needing to go to relays. Clifford Heath. Nope. The lack of isolation is NOT in the combiner. Assuming a reasonable 75 ohm termination on all ports, a good combiner can deliver 20 to 50dB isolation over the VHF-UHF TV band. I could replace the splitter/combiner with a 6dB resistive power divider/combiner, which has 6dB of isolation, and get the same problems at a 3dB lower signal level. Resistive power divider/combiner: https://www.microwaves101.com/encyclopedias/resistive-power-splitters A proper splitter: http://802.11junk.com/jeffl/crud/CATV-splitter.png Good splitter/combiner and total crap splitter/combiner: http://802.11junk.com/jeffl/crud/CATV-splitters.jpg Anyway, the problem is the isolation between antennas. If both antennas can pickup the same signal, from the same station, the signals are going to add or cancel depending on the phase and amplitude. If there is a phase delay between these two signals, they will act much exactly as if there was a multipath problem. ATSC 8-VSB has some limited protection against multipath, but I wouldn't count on it. The symptoms manifest themselves as everything that could possibly trash a DTV signal. Fluttering, Stuttering, freezing, pixellation, rainbow color light shows, signal loss, etc. As I mentioned in a previous rant, the degree of cancellation and impairment is frequency dependent, which means I can't easily use a simple phase shifter to remedy the situation. I found some reference which suggested that one can see ghosts on a DTV with multipath. I never saw it or if they were there, they were buried under the light show and pixellation. Someone is sure to ask why then do two stacked antennas work? https://www.google.com/search?q=tv+antenna+stacking&tbm=isch These work because both antennas involved are looking at the same station, which produces the same signal level at the same phase at each antenna. Therefore, they can safely be combined, where the two signals add in phase, and therefore produce 3dB more effective anenna gain. Incidentally, I originally started by building a DPST PIN diode switch which selected which antenna was active by which coax cable had DC supplied to it. However, I made a stupid mistake and couldn't get it to function correctly. Since I was burning time and loosing money on this particular customer, so I took the easy way out and used a pair of spare latching relays and two push buttons from an HF antenna tuner project. Bottom line: RF is magic. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#15
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Antenna rotator question
On Tue, 2 May 2017 15:22:23 -0700 (PDT), "Ron D."
wrote: I like the first users comments: "Having a rotating antenna was not the solution because with today's digital tuners, every time you rotate the Antenna, you must rescan your channels." I guess he doesn't know how to manually add channels. with current Samsung so called "Smart TV's" it's not possible to add a channel. I have confirmation from Samsung. Sigh. I've been told to avoid anything called amazing, magic, miracle, plus, super, and such. I guess I now have to add smart to the banned list. I just checked a Visio VX240M TV: http://802.11junk.com/jeffl/crud/Visio%20Channel%20Skip.jpg It starts out by skipping all channels and sub-channels. You can then go down the shopping list of channels and select which ones to NOT skip. Kinda backwards, but easy enough. The TV also has a "limited scan" which allows the user to set channel areas to re-scan complete with limiting the scan to digital, analog, or both. I have a Samsung TV at home. I'll see what it can do later tonite. - USUALLY you can use the remote to select the physical channel and the TV will tune to the first virtual channel on that frequency. This is the preferred way the US government would like it to work. Channel up/down will then tune the sub-channels. I don;t yet have confirmation that an unscanned channel works that way, but I think it will. I have a TV tuner that will not work that way at all. It reports the actual center frequency in MHz of the scanned channels, not the physical channel, but you need the physical channel to add a single channel. You basically "scan" the physical channel and add. This "stupid" $1000 tuner won;t even update the display when entering a channel digit. The on-screen display shows the remote entered digit. The display on the tuner does not. A CECB I have allows one to add "scanned" channels to the existing scan. Nice mess. In the daze of analog TV VSB (vestigial sideband), the frequency of a TV channel was by the carrier frequency. This worked because the signal was asymmetrical. Symmetrical modulation schemes, such as FM, used the center frequency. SSB continued to use the carrier frequency. Meanwhile, the FCC uses the center frequency for most everything. Along came DTV, without a carrier frequency, so it was decided to use the center frequency. That generally satisfied the tech types. However, the station owners wanted to retain their old channel designators, even if the channel frequency was quite different. This was allegedly to avoid listener confusion, but did quite the opposite. I was told that it was temporary, but that doesn't seem to be happening. The best laid plans... One way to avoid having to deal with two sets of channel numbers would be to replace the real OTA channel number with that channels center frequency. That's apparently what was done in your expensive tuner. Whether the GUM (great unwashed masses) could handle the concept is debatable. They certainly are having problems with todays virtual channel system. Another proposal that came and went was to replace the virtual channels with the stations call letters. This probably would have worked with an internet connected TV that could search a suitable database. However, the present system was thrown together before most everyone had internet available, so that went nowhere. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#16
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Antenna rotator question
On Tue, 2 May 2017 15:31:40 -0700 (PDT), "Ron D."
wrote: Incidently, The CECB reports signal strength in 0 to 100 arbitrary units. The "Dumb" Samsung TV just reports s/n ratio The $1000 tuner reports both s/n and signal strength in real units. The 0 to 100 is not quite arbitrary. It starts out as an 8 bit number (0 to 255) from the receiver demodulator. That gets fed to a microprocessor, which converts it to 0 to 100. That's because most users do not count in binary or hex, and must therefore be supplied with their numbers in decimal format. Seems rational. In cellular handsets, there is a conversion algorithm or lookup table that relates actual signal strength at the receiver input to the 0 to 100 numbers. There is also a conversion to the number of bars (usually 5 bars), which are totally at the discretion of the handset manufacturer. That's what got Apple in trouble when they initially provided a linearized conversion from RSSI to bars and discovered that it made the iPhone 4 looks bad when the user grabbed the antenna. Ok, back to the TV. The SNR (signal to noise ratio) in not the usual analog style: (signal + noise + distortion) / (noise + distortion) Instead it's based on the BER (bit error rate) or MER (modulation error rate). Basically, it's a measure of how many errors the receive has to deal with in order to display a decent picture. The more errors that need correction, the lower the SNR. I believe that there's yet another lookup table correlating the BER to what the SNR would be if it were an analog receiver, but I'm not sure that this is really true. http://blog.solidsignal.com/content.php/2768-DTV-Antenna-Help-and-a-touch-of-SNR-BER-MER What I wanna see is Eb/N0 (energy per bit to noise power spectral density ratio): https://en.wikipedia.org/wiki/Eb/N0 This for European DVB, but the theory is about the same for US DTV: "Bit Error Ratio BER in DVB as a Function of S/N" https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_notes/7bm03/7BM03_4E.pdf -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#17
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Antenna rotator question
On 03/05/17 10:28, Jeff Liebermann wrote:
On Wed, 3 May 2017 07:47:12 +1000, Clifford Heath wrote: It seems as though it should be straightforward to feed power up the co-ax (ala masthead amplifiers) to drive a pair of isolation amps/buffer before a combiner. That could give you a lot more isolation, without needing to go to relays. Clifford Heath. Nope. The lack of isolation is NOT in the combiner. Assuming a reasonable 75 ohm termination on all ports, a good combiner can deliver 20 to 50dB isolation over the VHF-UHF TV band. I could replace the splitter/combiner with a 6dB resistive power divider/combiner, which has 6dB of isolation, and get the same problems at a 3dB lower signal level. Resistive power divider/combiner: https://www.microwaves101.com/encyclopedias/resistive-power-splitters A proper splitter: http://802.11junk.com/jeffl/crud/CATV-splitter.png Good splitter/combiner and total crap splitter/combiner: http://802.11junk.com/jeffl/crud/CATV-splitters.jpg Anyway, the problem is the isolation between antennas. If both antennas can pickup the same signal, from the same station, the signals are going to add or cancel depending on the phase and amplitude. If there is a phase delay between these two signals, they will act much exactly as if there was a multipath problem. ATSC 8-VSB has some limited protection against multipath, but I wouldn't count on it. The symptoms manifest themselves as everything that could possibly trash a DTV signal. Fluttering, Stuttering, freezing, pixellation, rainbow color light shows, signal loss, etc. As I mentioned in a previous rant, the degree of cancellation and impairment is frequency dependent, which means I can't easily use a simple phase shifter to remedy the situation. I found some reference which suggested that one can see ghosts on a DTV with multipath. I never saw it or if they were there, they were buried under the light show and pixellation. Someone is sure to ask why then do two stacked antennas work? https://www.google.com/search?q=tv+antenna+stacking&tbm=isch These work because both antennas involved are looking at the same station, which produces the same signal level at the same phase at each antenna. Therefore, they can safely be combined, where the two signals add in phase, and therefore produce 3dB more effective anenna gain. Incidentally, I originally started by building a DPST PIN diode switch which selected which antenna was active by which coax cable had DC supplied to it. However, I made a stupid mistake and couldn't get it to function correctly. Since I was burning time and loosing money on this particular customer, so I took the easy way out and used a pair of spare latching relays and two push buttons from an HF antenna tuner project. Bottom line: RF is magic. Ok, well in that case, just use an imposed DC level (+ve or -ve) to enable one of two switch diodes. Whichever diode is forward biassed passes that antenna's signal. Simpler and cheaper than relays. Clifford Heath. |
#18
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Antenna rotator question
On Wed, 3 May 2017 12:26:15 +1000, Clifford Heath
wrote: Ok, well in that case, just use an imposed DC level (+ve or -ve) to enable one of two switch diodes. Whichever diode is forward biassed passes that antenna's signal. Simpler and cheaper than relays. Clifford Heath. I used 4 PIN diodes. I had a bag of Motorola MPN3401 diodes handy. http://images.ihscontent.net/vipimages/VipMasterIC/IC/FSCL/FSCLS06284/FSCLS06284-1.pdf As you suggested, I used a bipolar switching arrangment. On each antenna, a pass diode would conduct the signal from the antenna to the receiver, while the other diode was reverse biased and effectively disconnected. At the same time, the other antenna did the opposite. The pass diode was reverse biased off, while the other diode would short the antenna to ground. Something close to this, but with bipolar power arrangement: http://www.analog.com/-/media/images/analog-dialogue/en/volume-44/number-1/articles/driving-pin-diodes-with-op-amps/pin_diode-fig-05.jpg?la=en However, it didn't work. I wasn't interested in climbing the roof, dropping the mast, and dragging a pile of test equipment to the roof for troubleshooting the problem. So, I just built a relay replacement, which didn't sweep so good on the bench, but worked well enough when installed. There were various reasons for this approach. I vaguely recall that I was scheduled to go sailing the next day or something similar. Thinking about the problem, my guess(tm) is that either I used the wrong ferrite beads and/or chokes to isolate the PIN diodes from the applied DC, or I used the wrong value coupling caps. I also made the capital mistake of not sweeping the circuit before attempting to install it. It was such a simple circuit. What could possibly go wrong? Anyway, if I had to do it again, I would use the same approach with the possible addition of FM and cellular RF notch filters. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#19
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Antenna rotator question
Nice mess. In the daze of analog TV VSB (vestigial sideband), the frequency of a TV channel was by the carrier frequency. This worked because the signal was asymmetrical. Symmetrical modulation schemes, such as FM, used the center frequency. SSB continued to use the carrier frequency. Meanwhile, the FCC uses the center frequency for most everything. Along came DTV, without a carrier frequency, so it was decided to use the center frequency. That generally satisfied the tech types. I totally agree. I do have equipment that can measure BER and signal strength, but it was an early adopter sort of thing and not convenient to use. So, rotators are really foreign to Samsung. That tuner is just plain weird because I need the physical channel re-scan for virtual channels and it only reports the center frequency. In the ATSC specs there is a center frequency field and sometimes it's wrong. The $1000 tuner can;t do Daylight Savings Time properly, nor can it do the EPG properly. Incidentally, this http://auroramultimedia.com/products/vtune-pro-4k/ is the high end tuner. It has other quirks too. I think a big issue for them is cable cards fell out of favor or don't exist anymore. It's grand scheme of things is to put the output on an IPTV/RF modulator so I can watch on my laptop. I just haven't got there yet. As another ASIDE (sorry), I want a way to take analog L/R and upconvert to AC3 5.1 in a "Audio Only" TV mode over HDMI, so I can put an AM/FM tuner on an ATSC channel. |
#20
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Antenna rotator question
On Wed, 3 May 2017 11:52:37 -0700 (PDT), "Ron D."
wrote: So, rotators are really foreign to Samsung. Yep. I fired up my Samsung P2570HD TV and got an unpleasant surprise: https://www.newegg.com/Product/Product.aspx?Item=N82E16824001335 When I scanned for active channels, it didn't find any channels. I tried it several times, on several antennas, and got the same results. No channels. Since the HDMI, composite, VGA, and DVI inputs all work normally, my guess(tm) is the tuner is blown. Looking at the available scan settings, it gets even stranger. I can add a channel manually, but there doesn't seem to be any way to remove a channel. Of course, since I can't test it, I'm sure about this. Offhand, I would say you're correct, that Samsung doesn't make it easy to use a rotator or multiple antennas. That tuner is just plain weird because I need the physical channel re-scan for virtual channels and it only reports the center frequency. In the ATSC specs there is a center frequency field and sometimes it's wrong. Is the virtual channel number correct? Does it even have a virtual channel number? The $1000 tuner can;t do Daylight Savings Time properly, The US congress critters tweaked the beginning and end of DST in order to somehow save energy in 2007. Many devices didn't clean up their DST act for many years after that. nor can it do the EPG properly. Incidentally, this http://auroramultimedia.com/products/vtune-pro-4k/ is the high end tuner. It has other quirks too. If it does IPTV, it must surely do NTP (network time protocol) which includes proper DST shifts. I don't think there's a single device available that does EPG (electronic program guide) without bugs, added monthly costs, or both. However, don't blame the guide vendor. Stations often change their programming at the last moment for odd reasons (sponsor pressure, current events, ongoing disaster coverage, etc). I think a big issue for them is cable cards fell out of favor or don't exist anymore. It didn't "fall out of favor". It was massacred by the cable companies, who preferred to rake in the cash from equipment leases than to allow the GUM (great unwashed masses) to own their own equipment. Never mind that the FCC ordered the availability of user owned cable equipment. Comcast also made it look like a frontal attack on Tivo, who is the major beneficiary in CableCard based installations. Incidentally, Comast raised the price of them allowing a CableCard from about $2/month to $10 or $15/month (I couldn't find the exact price) so as to be equal with the cost of leasing a set top box. So much for affordable. It's grand scheme of things is to put the output on an IPTV/RF modulator so I can watch on my laptop. I just haven't got there yet. RF Modulator? That's rather low quality video if fed from composite video. What most users want is the ability to record HD programming without DRM issues. A CableCard in a tuner can do that if digitized video can be delivered via ethernet (thus avoiding the encrypted HDMI problem). No, I won't tell you how to do it. As another ASIDE (sorry), I want a way to take analog L/R and upconvert to AC3 5.1 in a "Audio Only" TV mode over HDMI, so I can put an AM/FM tuner on an ATSC channel. Why bother? Most OTA radio stations also stream over the internet. Just point your web browsers to the stations URL and you have streaming AM/FM audio on the laptop. However, if you do find a station that does NOT stream, just plug an RTL2832U plus R820T2 SDR receiver dongle into a USB port, run one of a dozen receiver control programs, and you have an AM/FM/ham/WX/scanner/whatever receiver. https://learn.adafruit.com/getting-started-with-rtl-sdr-and-sdr-sharp/sdr-number-fm-radio Sigh. Topic drift at it's best. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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Antenna rotator question
Offhand, I would say you're correct, that Samsung doesn't make it easy
to use a rotator or multiple antennas. Oops, for your Samsung. Is the virtual channel number correct? Does it even have a virtual channel number? Virtual is fine. In the details (MENU) In the DTV signal strength have: freq: off air 57.00 MHz Power level and s/n with weak Normal type things. ss in dbm and s/n in db In Manual scan, I'm asked to enter the "Channel Number" which is the physical one. DST: It had already changed this year at 10 PM, not 2 AM. EPG: My Bad, the remote labels it as such. It would be what's gonna happen on the current channel. That's totally part of the ATSC signal. It messes up a few hours before midnight. It's like 11:37 pm and it has programs that start at 12:30. After midnight it gets lots more. Another $50 government box works. It's not the Master EPG programming schedule for all channels. cable card- Yep. RF Modulator? Sort of. One of these: http://english.dsdvb.com/Upload/file...0304024149.pdf 4 channels of 4K HD video on 4 RF channels and 4 IP TV channels. Right now my wired Ethernet is too slow and wireless is even slower. I have not tried to see the RF output but I did measure a decent BER and signal strength on a test instrument w/o video) Streaming: two-foldRF Modulator? Be able to watch ATSC TV on the laptop (Slingbox like AM/FM or anything L/R to HDMI ATSC Audio only in AC3 or Dolby Digital. The smart TV does have a web browser, but you can't tell the TV to just do audio. You end up with a web browser screen with audio. For video the Samsung won't do Flash. ATSC TV's with converter boxes are everywhere in the house. My elderly Mom likes AM radio and can't yet operate the TV that detailed. She can't at this point watch youtube on the TV to watch the Sunday Mass. Like I said, the TV is really dumb. A wireless USB keyboard won't work on youtube. Well,the arrows work, but the characters don't. They blame the app maker - i.e. Google for this. Nearly useless or DUMB! |
#22
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Antenna rotator question
Jeff Liebermann wrote: "
The US congress critters tweaked the beginning and end of DST in order to somehow save energy in 2007. Many devices didn't clean up their DST act for many years after that. " Most of Congress probably believes Daylight Saving adds daylight! Remmber: they don't read what they pass. DST actually increases overall energy consumption, but lazy people like it because it delays sunrise and they can stay up later and sleep in. |
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Antenna rotator question
thekma @ drooling . retard . com wrote in message
... DST Theckmaaaaah the village idiot starts flogging a dead hobbyhorse again! (not even in season ...) actually increases overall energy consumption, retarded phony info that theckmah plucked from his festering rectum but lazy people like it because it delays sunrise and they can stay up later and sleep in. The brain damage is obvious. Understanding daylight saving time involves understanding simple numbers, but when it comes to simple numbers, Theckkkahhhmaaammmaaaah is a simpleton retard. |
#24
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Antenna rotator question
On Sun, 7 May 2017 03:48:18 -0700 (PDT), wrote:
Jeff Liebermann wrote: " The US congress critters tweaked the beginning and end of DST in order to somehow save energy in 2007. Many devices didn't clean up their DST act for many years after that. " Most of Congress probably believes Daylight Saving adds daylight! Remmber: they don't read what they pass. Maybe, but most voters also don't read the various initiatives and referendums on which they vote. Worse, few voters could recite the names of their local government representatives, as well as whom and what they represent and advocate. It's the blind leading the blind. So, why does representative government still work? Because elected representatives have staff to read through the various measures and deal with the constituency. Afterwards, they provide a very simplified summary for the representative to read and digest. DST actually increases overall energy consumption, but lazy people like it because it delays sunrise and they can stay up later and sleep in. There have been various research projects, few of which seem to be objective and unbiased. One of the more comical that I read was a survey of families paid to change their clocks according to the old DST system, and then comparing energy consumption only in the approximately two months that were involved in the change. If I find a link, I'll post it. The results were almost random, but that was apparently fixed by carefully cherry picking the data from those who most closely followed the test guidelines. Some tests and surveys: https://en.wikipedia.org/wiki/Daylight_saving_time#Energy_use I think this might be it: "The United States Department of Energy (DOE) concluded in a 2008 report that the 2007 United States extension of DST saved 0.5% of electricity usage during the extended period. [90] This report analyzed only the extension, not the full eight months of DST, and did not examine the use of heating fuels." Perhaps we can escape the horrors of DST by getting away from the rigid 8 hr work day, and replacing it with a 6 hr winter work day, and a 12 hr summer work day, when there are more hours of sunlight. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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Antenna rotator question
Jeff Liebermann wrote: "
"The United States Department of Energy (DOE) concluded in a 2008 report that the 2007 United States extension of DST saved 0.5"" The DOE can publish any conclusions that the utilties find favor with. "Perhaps we can escape the horrors of DST by getting away from the rigid 8 hr work day, and replacing it with a 6 hr winter work day, and a 12 hr summer work day, when there are more hours of sunlight. " Perhaps we can escape the horrors of DST by shifting business hours earlier in the day. '9 to 5' makes a nice song on the radio, but it wastes a lot of early morning daylight. I personally would quickly embrace an 8-4 first shift, so the workday is rarely ever impinged upon by darkness. Getting folks to go to bed before midnight is another challenge, however. |
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Antenna rotator question
On 5/1/2017 11:45 AM, Jeff Liebermann wrote:
On Mon, 1 May 2017 01:42:17 -0700 (PDT), wrote: My point was he might be able to use multiple antennas with diplexers and get one overall feed that could be treated like the cable company - all channels available all the time with no adjusting. G² Nope. A few problems: 1. A diplexer splits the frequencies between VHF and UHF channels. If one antenna is VHF and the other is UHF, it will work, but only if the stations in one direction are all VHF and the other direction are UHF. Methinks that's unlikely to happen. 2. If you replace the diplexer with a combiner/splitter, you theoretically can get both VHF and UHF signals from both antennas at the same time without switching. I think that's what you're suggesting. However, that doesn't work because the same signals are picked up by both antenna at the same time. If the signal are in phase, then the signals combine and you get good reception. If they're 180 degrees out of phase, you get cancellation and no signal. However, that's an over-simplification. What really happens is that the signal is 6 MHz wide and the phase cancellation varies with frequency. Some of the 6 MHz wide frequency range gets added, but other frequencies in this range get cancelled. The result is a very rocky and erratic frequency response which makes an ugly mess of the signal. Bad idea. Phase issues are easy to deal with. Co-locate the antennas so the signals are in phase and use the same length of cable between each antenna and the combiner. Now all frequencies are always in phase. A short run to the mast mounted amp and you are done. 3. You can make it work with two antennas in two directions using a coax switch. Only one antenna is connected at a time so there is no interaction. You might need two coax cables from the mast to the TV where the switch is located. Or, you can setup a remote antenna switch. Or, you can setup a cross-over switch and two receivers, where you can record on one receiver/antenna combination, while viewing on the other. -- Rick C |
#27
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Antenna rotator question
I don't like the new DST schedule because it gets dark when it's time to do yard work during the weekday.
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#28
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Antenna rotator question
Ron D wrote: "
8:04 PMRon D. I don't like the new DST schedule because it gets dark when it's time to do yard work during the weekday. " ? DST in United States runs from second Sunday in March to first Sunday in November. Clocks are +1 hour during that entire period. 'Noon' is at 1pm (by the clock) during that period. |
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Antenna rotator question
On Mon, 8 May 2017 17:04:46 -0700 (PDT), "Ron D."
wrote: I don't like the new DST schedule because it gets dark when it's time to do yard work during the weekday. At this time, sunset on the left coast is at about 8PM. https://www.timeanddate.com/sun/usa/santa-cruz You do yard work at that 8PM? If you must mow in the dark, just add headlights to your lawn mower. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#30
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Antenna rotator question
On Monday, May 8, 2017 at 8:04:51 PM UTC-4, Ron D. wrote:
I don't like the new DST schedule because it gets dark when it's time to do yard work during the weekday. Remember, the moon is much more useful than the sun. The moon gives light in the night, when it's actually needed. |
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Antenna rotator question
On Wednesday, May 10, 2017 at 4:18:06 PM UTC-4, Tim R wrote:
Remember, the moon is much more useful than the sun. The moon gives light in the night, when it's actually needed. It is this sort of reasoning that explains the American Political System. Peter Wieck Melrose Park, PA |
#32
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Antenna rotator question
it's the fall change back that bothers me, not the summer one, but now it doesn't matter because 5:30 PM doesn't mean what it used to. "Home from work and it's dark".
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#33
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Antenna rotator question
Ron D:
So you don't like Standard time, when 12pm corresponds with noon. Ok, well see about getting up earlier, and if your job offers an earlier shift, like 8-4 or something. I am the only person in America I know who wouldn't mind 4:30 sunrises where I live, in June! I would actually be up at that time, doing errands around the house. I'm normally in bed by 8 anyway, which it actually is right now - even though the clocks all say 9pm. |
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Antenna rotator question
theckkkmaah @ retard . shortbus . edu took a steaming dump
So you don't like Standard time, FLUUUUUUSH Theckhhhmah, you retarded dumb****! You're one of usenet's village idiots, and you just cannot stop flogging the rotted corpse of your DST hobbyhorse (that's DST; look it up if you have to). But it's dead. It's bleeding demised. Maybe you can get a grownup to adjust your clocks twice a year, if you're just too stupid to do it yourself. You keep telling people when they should wake up and when they should go to sleep. Maybe you should just worry about your own pathetic life, and stop being so ****ing lazy. Nobody wants to live their lives according to some retarded schedule dreamed up by a microcephalic dumb**** like you. Just live on TDT (Theckmahhh Dumb**** Time), that's fine, as long as you're ready and wearing your hockey helmet when the short bus comes to take you to your job at the hire-the-retard used crap store. SFH, LB, FCKWAFA AOCADFR. RLB? LB??? |
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Antenna rotator question
Jeff Liebermann wrote:
I don't think there's a single device available that does EPG (electronic program guide) without bugs, added monthly costs, or both. However, don't blame the guide vendor. Stations often change their programming at the last moment for odd reasons (sponsor pressure, current events, ongoing disaster coverage, etc). The original EPG was a service provided by United Video Cablevision's microwave division. Their computers were in Tulsa OK, and they were linked to their WGN uplink in Chicago by a pair of leased phone lines. One pair fed the data North to Chicago, while the second echoed it back to their PDP -11 computers in Tulsa OK. It was transmitted on a subcarrier along with WGN to CATV headends across the country. The demod and processor was a 6502 based rack mounted computer that put out NTSC color video. I got into a very heated argument with the head of our Microwave division, as I told him how to uplink the signal from the computer site, but leave it on the WGN transponder. He told me it was impossible, so I told him that if he couldn't do it, he should quit his job. Two months later, they announced the change, and that HIS idea was saving the company over $15K per month for the leased lines. -- Never **** off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-) |
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