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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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Subarrier FM radio
Are such radios sold in the USA via the internet? Is the station really
"fixed"? Someone gave my uncle a radio which is said to have a special "chip" that receives a Greek radio station. He mentioned to me that years ago he had another one that suddenly switched to a Philipine station and he gave it to a Filipino colleague. Amazon and Alibaba have such Metrosonix radios but not station specific, but also do not seem to allow being sold in the USA. THe search terms I used were SCA FM radio. - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] |
#3
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Subarrier FM radio
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#4
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Subarrier FM radio
wrote:
Are such radios sold in the USA via the internet? Is the station really "fixed"? Someone gave my uncle a radio which is said to have a special "chip" that receives a Greek radio station. He mentioned to me that years ago he had another one that suddenly switched to a Philipine station and he gave it to a Filipino colleague. Amazon and Alibaba have such Metrosonix radios but not station specific, but also do not seem to allow being sold in the USA. THe search terms I used were SCA FM radio. I'd be kind of suprised if any of those stations were still active. Here in Chicago, it was probably the early 90's that was the height of popularity, I think there were 2 greek stations, one polish and 3 or 4 others that were probably used for pocket pagers (normally silent except for bursts of tones or a data carrier). The basic idea was the "broadcaster" would get the station from overseas (probably via a C-Band dish/receiver) and rebroadcast it on someones sca channel (an ordinary FM station set up for it). They would then rent the modified radio for like $5 a month or sell you it with a "lifetime" subscription for $100 or around there. Usually the radios, which were cheap garbage imports, were fixed to the primary channel by crazy glueing the tuning shaft or otherwise disabling the tuner. The boards were just simple 4 wire things, power, ground, detector in and audio out. Since they were meant as a dedicated service, there wasn't any reason to make the radio work both ways, normal and special. These were all handmade and varied quite a bit, depending on what make/models the local wholesale importers had. The adapters were numerous, the most basic/simple one used a PLL chip (either NE565 or NE566, maybe) and off the shelf resistors and capacitors. They usually worked well enough but had problems with leakage from the main carrier. There was another design, I want to say MC1340 as the centerpeice which had the best performance (dead quiet) but required custom rf coils and oddball capacitors, still simple to build but upped the cost quite a bit. In any case the boards were probably not even 2"x2" and were easily tucked in somewhere, usually the battery holder (4xC or D cells). As far as legality of them, although I don't think anyone considered them a crime to own, you couldn't open up a cottage industry by building them and selling them. There was no reason to stop anyone from making one, but they fell into that gray area where selling one was in some violation of FCC rules and regs for 3rd party interception of a private (or intended private) broadcast. The thing is, once the internet and access to it became the norm (early 2000's), I really don't think those rebroadcasters could survive. On nearly any platform or device there is usually one or two applications available for listening to radio stations from aroound the world, if not dozens of websites that retransmit them. I'd guess there are plenty of 80+ year old grandmothers from the old country who can work turning on and off a radio rather than firing up a laptop but I doubt there is enough to make any money off them. -bruce |
#5
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Subarrier FM radio
On Sat, 28 May 2016 22:13:54 -0700 (PDT), wrote:
"SCA sub-carriers never went above about 80Khz, so there was no increase in occupied bandwidth. IBOC changed all that by grabbing all the spectrum between +/-100kHz and +/-200KHz: " I don't know how familiar you are with high end audio but there are tuners out there that can switch between narrow and wide band IF, and I think a few, very few, variable. The wider bandwidth results in much lower distortion. However then there is more noise and you need a stronger signal. What little I've done with broadcast FM was at various radio stations and designing some low end receivers. That was also long ago, so I'm fairly well behind on the technology. However, if "high end" means "high price", I've fixed a few of these systems: http://www.elanhomesystems.com If you've ever swept a decent analog FM receiver, you may have noticed that the IF bandwidth is much wider than the occupied bandwidth (200KHz) of the signal. In order to keep the group delay fairly constant within the IF bandwidth, this was necessary. That meant that while the audio was very good quality, the receiver would pickup junk from adjacent channels. Sensitivity is limited by the receiver front end and is unaffected by the wider bandwidth. Roll forward a few decades and we are now blessed with all digital receivers. The best example is the Sony XDR-F1HD tuner: http://ham-radio.com/k6sti/xdr-f1hd.htm http://www.amazon.com/Sony-XDR-F1HD-Radio-Discontinued-Manufacturer/dp/B00168Q248 These typically sell on eBay for $150 to $250 or $500 with some necessary modifications. Seems to be a demand: http://www.ebay.com/sch/i.html?_from=R40&_nkw=XDR-F1HD&LH_Complete=1&LH_Sold=1 The difference is that this receiver has a "brick wall" digital IF filter that doesn't need to be excessively wide in order to get low group delay and low distortion. The narrower bandwidth is also good for reducing much of the alternate channel noise produced by IBOC (HD Radio) signals. Meanwhile, the lower end FM receivers are also deriving benefits from digital IF and demodulators. The Sony tuner uses an NXP/Philips SAF7730 chip while most of the low end stuff uses various Silicon Labs AM/FM chips: http://www.silabs.com/products/audio/fm-am-receiver/ http://www.silabs.com/products/audio/fmreceivers/ Basically, it's almost an SDR (software defined radio) with most everything in a single chip. Tecsun uses these chips in their various radios. Plugged into a proper audio amp and speakers, they sound very good, with little IBOC junk from the adjacent channels. (Note: Not all Tecsun radios use digital receiver chips). Actually it is all going digital soon, a couple of countries are in the process of that right now. No, it's not, at least in the USA. The FCC, in its infinite wisdom, has endorse exactly one proprietary and expensive standard (IBOC) totally owned and licensed by iBiquity. As usual, half measures don't work. In this case, the broadcast industry wasn't quite sure if they were going to commit to doing IBOC, so instead of 100% digital FM, iBiquity was forced to provide the half ass analog/digital compatible system that we're cursed with today. Incidentally, the failed AM stereo system following a similar life cycle demonstrating that the FCC and the industry doesn't learn from their expensive mistakes. In 2012, a made a graph of the number of HD Radio stations in the SF Bay area and in the USA. http://802.11junk.com/jeffl/crud/hd-radio-stations-calif.jpg http://802.11junk.com/jeffl/crud/hd_radio_stations.jpg http://www.stateofthemedia.org/2013/audio-digital-drives-listener-experience/9-number-of-stations-dropping-hd-outnumber-those-adopting-in-2012/ There's actually been a decrease in stations, that have unplugged their HD Radio equipment since 2012 but I don't have numbers handy. I know little (or nothing) of what's going on with DAB (digital audio broadcasting) as it's not used in the USA: https://en.wikipedia.org/wiki/Digital_audio_broadcasting -- 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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Subarrier FM radio
In article ,
wrote: Now, this digital information bothers high fidelity tuners. they are coming out with modifications to the ones with the worst susceptibility. I mean even tuners built in the 1970s. Some of them were damn good. Now, the digital information makes for like "hash" or whatever, an unpleasant background noise. I saw a modification for it and surprising to me is it was not something to cut the IF bandwidth, it was strictly in the ratio detector. It seems the newer quadrature detectors don't have much of a problem with this, so far I saw. The digital noise is commonly a problem as the result of the way stereo demultiplexing works. The higher-frequency components of the FM detector's output are mixed against the 38 kHz local oscillator, thus doing an AM demodulation of the L-R subcarrier band which lies on either side of 38 kHz. Many MPX decoders use a simple switching-mixer architecture, and these will end up detecting both the signal around 38 kHz, but also whatever is present in the neighborhood of the third and fifth harmonic of 38 kHz. Since that's where the digital subcarriers often line, the digital signal ends up as sideband noise in the L-R difference signal, and (unless you switch the tuner to "mono") ends up in the left and right channel audio. There are a number of ways to fix this. One is to filter the FM detector output signal before it goes to the MPX chip... either a low-pass filter (knee somewhere about 60 kHz), or notch filters centered on the odd harmonics of 38 kHz, or both. Another approach is to demodulate the MPX signal using a design which is inherently not sensitive to the 38 kHz harmonic regions... e.g. a true multiplying mixer using a 38 kHz sinewave local oscillator (rather than a square wave or switching design), or a Walsh-function decoder using a stepped wave which has no 3rd or 5th harmonic content (some Sansui tuners do this). Modern DSP-based MPX decoders could do any of these. http://ham-radio.com/k6sti/hdrsn.htm has a nice overview of the problem and solutions. |
#7
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Subarrier FM radio
On Sun, 29 May 2016 11:13:09 -0700, (Dave
Platt) wrote: http://ham-radio.com/k6sti/hdrsn.htm has a nice overview of the problem and solutions. That article is on HD Radio (IBOC, iBiquity, dismal radio, etc) and not about conventional FM stereo. While the mechanism for generating the noise that you don't want to hear is similar, the technology, solutions, and sources of noise are quite different. For example, there's no mixing required for the excessive occupied bandwidth of IBOC to ruin your day. Incidentally, Brian Beezley has written several other articles on HD Radio and tuners: http://ham-radio.com/k6sti/ See "HD Radio" section at lower right and various equipment reviews at the upper right. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#8
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Subarrier FM radio
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#9
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Subarrier FM radio
Interesting, in fact everybody, interesting.
Next we need a thread on what all they crammed into the NTSC TV signal. Like PRO audio which was another SAP essentially, the VITS or VIR, closed captioning, ghost cancelling reference and who knows what else. Man's innate lust to cram as much as possible into any given bandwidth. With TV, they wasted it. They went digital because NTSC takes too much bandwidth and has limited resolution. The problem is they cannot come up with any decent programming anymore. In other words, the resolution doesn't matter if there's nothing to watch. I don't need 2,000 line resolution to watch Gunsmoke. Just like I don't need 24 bit/96 KHz sampling to listen to music from the 1960s. |
#11
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Subarrier FM radio
On Monday, May 30, 2016 at 9:43:06 AM UTC-7, wrote:
With TV, they wasted it. They went digital because NTSC takes too much bandwidth and has limited resolution. The problem is they cannot come up with any decent programming anymore. Digital would take more bandwidth, except they use compression to reduce the amount of data sent. In the 1950s, there was not enough computing power in the whole world to do the compression and decoding in real time. |
#12
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Subarrier FM radio
Wow! incredible answers, thanks
- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] |
#13
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Subarrier FM radio
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#14
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Subarrier FM radio
"Actually, NTSC color makes pretty good use of bandwidth when you're
constrained to all-analog" Right, but that is not what I meant. I meant none of this **** is worth watching. When I was a kid and we had like five channels we actually had to have a discussion on what to watch. Now hot only are there more TVs in the house than people, we got like 500 channels. There used to be shows that were entertaining, even though they were kinda like - junk. They were entertaining. Now we are relegated to watching people remodel houses or something, or Gordon Ramsay bitching out restaurant owners or some retired detective describing a 35 year old case, with re-enactment of course. Most other shows it looks like they let an eight year old kid work the camera, I mean they do EVERYTHING cameramen were taught not to do. It is ****ing unwatchable. In the 1960s and 1970s having a TV was a status symbol almost. Now, it has gotten so bad that NOT having one is, almost. Or at least leaving it turned off. "When it was introduced, compatible color was right at the cutting edge of (or maybe a bit beyond) technical feasibility for commercial (not to say consumer) electronics." Actually it could not be beyond since it worked. It redefined the cutting edge. Color TV is one of the few things the US can claim as its own invention. Other countries came later, albeit with better systems, but I am pretty sure we were first. I am not sure about FM stereo. Never really looked into it. I know that in Europe they use less modulation and thus less bandwidth. The de-emphasis is 50 uS not 75. I also had the US and European versions of the same album (Golden Earring - Moontan) and their version was cut with alot less groove modulation and had a huge leadout, putting most of the music where the groove velocity was greater and tracking error less. It sounded considerably better. I mean ALOT better. Seems like the US is all about loud. More modulation, more up compression, and even other tricks to sound louder. Idiots will put their graphic equalizers full tilt up, and have no idea how to properly use a dynamic range expander like a Pioneer RG-1 or RG-2. They think the right way is to turn the input level all the way up. Look asshole, if it was meant to be all the way up all the time why did they even put a control there ? But that is my opinion after much observation. LOUD is the "American" way. Wasn't it the US came out with laws about reporting the power output of amps ? I guess other countries have the same but that seems like something we probably did first. |
#15
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Subarrier FM radio
isw wrote: "In article ,
wrote: Interesting, in fact everybody, interesting. Next we need a thread on what all they crammed into the NTSC TV signal. Like PRO audio which was another SAP essentially, the VITS or VIR, closed captioning, ghost cancelling reference and who knows what else. Man's innate lust to cram as much as possible into any given bandwidth. With TV, they wasted it. Actually, NTSC color makes pretty good use of bandwidth when you're constrained to all-analog, vacuum-tube technology. When it was introduced, compatible color was right at the cutting edge of (or maybe a bit beyond) technical feasibility for commercial (not to say consumer) electronics. Isaac " And ATSC 1.0 color gamut is actually a hair smaller than that of the NTSC it replaced. |
#16
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Subarrier FM radio
"And ATSC 1.0 color gamut is actually a hair smaller than
that of the NTSC it replaced. " You lost me there, what do you mean by that ? The different broadcasting format should have nothing to do with the colors that can be displayed, that is a function of the panel, or CRT. (actually a plasma panel is like a CRT in a way but it just has multiple rays) Now LCD panels might be limited by the backlight. They cannot display any color that is not in the spectrum of the backlight. Actually they could not handle the colorimetry required for LED backlighting until recently when the new generation of LEDs cam out that actually have a phosphor. Older LEDs had very spikey outputs. If a color isn't there you must display two colors opposite the wavelength you want in the right proportion so the eye mixes it. It was just too much to deal with so they went with the CCFLs. |
#17
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Subarrier FM radio
jurb...gmail.com wrote: "You lost me there, what do you mean by that ? The different broadcasting format should
have nothing to do with the colors that can be displayed," To the contrary. A display may be capable of limitless color and dynamic range, but it can reproduce only what it is sent. |
#18
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Subarrier FM radio
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#19
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Subarrier FM radio
"If you're talking about PAL, which came later, quite good arguments can
be made that it's not better at all; just that its weaknesses are in different places." Well for one they eliminated the phase control. On US sets it was called the tint or hue control and it shifted the phase of either the chroma subcarrier or the oscillator. Their little scheme cancelled out the errors, which were mainly caused by poor frequency response which would shift the phase of the burst or even make the PLL in the TV have a phase error because part of the burst is cut off. However it happened, you sometimes needed to adjust the tint in the old days. Also, PAL was more lines. I think it was 50 Hz which would mean they needed a longer persistence phosphor. Also the horizontal rate was faster. They had quite a bit more resolution bt at the cost of frame rate. But that can be dealt with, you know movies in the theaters only used to be 24 frames per second right ? Well people did not really have a problem with that. They only reason it is a problem with a CRT is because the picture is drawn in a series of lines and that makes it more visible. A film projector is a whole different animal than a TV set. |
#20
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Subarrier FM radio
"To the contrary. A display may be capable of limitless
color and dynamic range, but it can reproduce only what it is sent. " Why wouldn't they send it ? |
#21
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Subarrier FM radio
2:40 wrote:
"To the contrary. A display may be capable of limitless color and dynamic range, but it can reproduce only what it is sent. " "Why wouldn't they send it ? " sigh... Simple: The color gamut triangle of the ATSC *standard* - what the STANDARD is capable of reproducing - is a tad smaller than that of NTSC. |
#22
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Subarrier FM radio
thekma @ gmail.com wrote in message
... 2:40 wrote: "To the contrary. A display may be capable of limitless color and dynamic range, but it can reproduce only what it is sent. " "Why wouldn't they send it ? " sigh... Simple: Not as simple as you say. The color gamut triangle of the ATSC *standard* - what the STANDARD is capable of reproducing - ATSC has no standard color gamut. Even with caps-lock, there is no STANDARD color gamut in ATSC. Rec. 709 is common for HD programming, and Rec. 601 is common with SD. But ATSC doesn't care; the primaries and the white point are specified in the stream. Maybe someday Rec, 2020 will be standard in a future version of ATSC, but for now, there is no such thing as an ATSC standard color gamut. is a tad smaller than that of NTSC. |
#23
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Subarrier FM radio
..... wrote: "STANDARD color gamut in ATSC. Rec. 709 is common for HD programming,
and Rec. 601 is common with SD. But ATSC doesn't care; the primaries and the white point are specified in the stream. Maybe someday Rec, 2020 will be standard in a future version of ATSC, but for now, there is no such thing as an ATSC standard color gamut. - show quoted text -" Butt the f out! Find someone worthwhile to stalk. Like someone you actually know. |
#24
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Subarrier FM radio
wrote in message
... .... wrote: "STANDARD color gamut in ATSC. Rec. 709 is common for HD programming, and Rec. 601 is common with SD. But ATSC doesn't care; the primaries and the white point are specified in the stream. Maybe someday Rec, 2020 will be standard in a future version of ATSC, but for now, there is no such thing as an ATSC standard color gamut. - show quoted text -" Butt the f out! Find someone worthwhile to stalk. Like someone you actually know. Sorry to disturb you with the simple facts concerning color gamuts in video standards. But there is no ATSC color gamut standard. NTSC has a very broad gamut, but NTSC is dead. Pointer's gamut is probably adequate for practical use. But ATSC doesn't care. It expect the primaries and white point to be specified in the stream; it's doesn't define them as a standard. You are obviously way too smart to understand that. Primary colors. White point. Pretty simple stuff. HFCUIS. LKF. FCK,WAFA. AASBDF. OK, li'l buddy? |
#26
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Subarrier FM radio
"Actually, 48 FPS as projected -- each frame was shown twice. "
Didn't know that. Makes sense though. I busted "them". I believe it was a commercial for a Sharp camcorder with good low light capabilities. They were showing what was ostensibly some kids birthday party or something. Well back then I always had six or seven head VCRs. I could tell when they pulled it down from the 48 Hz to 60 Hz. They showed each from twice but every so many cycles they would show it thrice. The video the showed was clearly on film because a camcorders does not use 24 FPS. (or 48) Nothing happened, WTF. I didn't buy one, I didn't initiate a class action lawsuit, in fact it is almost like who cares. Like now, I work on "pro" audio. Know what "pro" actually means here ? It means that the FTC and IHF standards do not apply. You got an amp the has 55 volt rails which yields about 100 WPC but they can call it 3,500 watts. Technical Pro is one of the worst offenders but I have seen worse. I saw one amp supposedly 1,000 watts that had a single TO-220 type chip output. There is no way this thing was even 100 WPC. But anyway, it is not the same with a DVD, with a good four (plus two audio) head VCR going frame by frame you can see the effect. Two frames would be the same and then three frames would be the same. And I am probably the only person in the world who knows they cheated. Technically, if their camcorder would work in as low light as that film it was not false advertising, and I really don't recall them saying the video was taken with their camcorder. But the implication was pretty strong. Come on, they are advertising a camcorder with good low light sensitivity, What does the viewer think when he sees a kids birthday party ? Just another example of the **** they can get away with. But the bottom line is I am so close to not giving a **** I can smell it. |
#27
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Subarrier FM radio
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#28
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Subarrier FM radio
Since it was on TV and not the silver screen, that implies that the recording was made on their camcorder. There would be no reason to transfer their camcorder tape to 24 FPS film.
They are busted. |
#29
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Subarrier FM radio
On Saturday, May 28, 2016 at 7:26:47 PM UTC-4, wrote:
Are such radios sold in the USA via the internet? Is the station really "fixed"? Someone gave my uncle a radio which is said to have a special "chip" that receives a Greek radio station. He mentioned to me that years ago he had another one that suddenly switched to a Philipine station and he gave it to a Filipino colleague. Amazon and Alibaba have such Metrosonix radios but not station specific, but also do not seem to allow being sold in the USA. THe search terms I used were SCA FM radio. - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] Visit Metrosonix.com, We manufacture and sell a wide variety of SCA radios. |
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