|
|
Post by Boomer on Aug 10, 2018 6:02:18 GMT
Added to TransmittersI put this under Transmitters since there's no section for receivers, but receivers do relate directly to transmitters.. In the early 1980s I was hearing reports on mainstream news outlets about the coming of stereo to AM. It was interesting, but lacked any kind of technical details beyond the fact you'd need a new radio to hear the stereo sounds, and I wondered how they would do it, thinking it must use the upper and lower sidebands of an AM signal for left and right channels. This article explained it more, and showed how to build a decoder board to add to mono radios to make them pick up stereo. It was a touchstone for me, an article that always came to mind when I'd think about AM stereo later on. I managed to track it down in the magazine found on line, from Radio Museum I believe. I've carefully opened it and OCRed their quick image scans, cleaned it up and recompiled it for small size PDF for my site, but I thought with the AM stereo interest at the ALPB, I'd post it here too. I've been hearing about members paying high prices for AM stereo receivers, but if you're savvy at electronics, you could still build the decoder from this article and save a lot of money. A company called Meduci sells cards like this with an updated decoder chip for less than $30. radio-electronics-am-stereo-decoder-1-1984.pdf (404.31 KB) Boomer
|
|
|
|
Post by mark on Aug 10, 2018 23:41:16 GMT
When I click on the link it won't go to the page.
|
|
|
|
Post by thelegacy on Aug 11, 2018 9:06:20 GMT
I was so happy when my broadcast engineer friend gave me a Sony SRF-A100. It opened doors for me and now at least I can monitor my station in C-Quam. He had obtained it when AM stations were giving these Radio's away. It's missing the battery door at the bottom so I have to use tape to keep the batteries in place. It also has an adapter jack but I don't think there is a way to recharge NiMH batteries with the Radio so I have to use my Tecsun PL380 to charge the batteries and then put them into the C-Quam Receiver until I get a desk charger.
It goes to 1640 Khz thank God so I was lucky there. The Radio works really well however and no crashing sounds when you adjust the volume or tone controls nor when switching to normal or Wide. Its analog tuning but easy to tune and I don't notice any drift. A really solid portable Radio and good for when I walk around testing to make sure C-Quam is receivable from my place to Sunset Grill.
My station is called C-Quam 1640 WAQM The Legacy. Everyone knows its AM Stereo as I mention it when I name the songs played as well as tell listeners how they can obtain a C-Quam Receiver. The slogan "Don't be caught with AM Radio that sounds like someone talking through their nose Go C-Quam Today!" is promoted hard and strong.
I plan on a playlist in the future with an entire weekend of super Wide Stereo tracks. Just as FM Stereo was promoted hard in the 70's I'm promoting C-Quam. Even telling listeners to use Ebay Alstralia or look for Radio's in Canada if they can't find them on Ebay US. The C-Quam AM Stereo Facebook page is also promoted where people can discuss C-Quam AM Stereo.
Radio stations and TV stations should have driven hard selling ads for C-Quam and if they had everyone would have them now. AM would have been saved too for these Radio's have way better receivers too. Its like AM Radio was sabotaged to fail and die due to FM Radio. I smell a rat. You still get some static if your near transformers but this effects the left channel more than the right in C-Quam. So even a News Talk station could have used it and in high interference areas you simply listen in right channel only. In the city that would have been a good help. So even all talk should have used C-Quam and the FCC should have made it mandatory.
Making C-Quam mandatory for Hobby AM Broadcasting if we ever get the 10 Watt service would keep the average joe from a transmitter and at the same time make AM listenable for those who want to listen to a Hobby Station. Since you can't buy an assembled transmitter in C-Quam again troublemakers can't easily get on the air and that was what some folks here wanted.
|
|
|
|
Post by Boomer on Aug 12, 2018 2:41:02 GMT
Hi Oldies Mark, not sure why it didn't work. It's a PDF file, and loaded to this page itself. If you're on Firefox, it should show in the browser window. Maybe it could be uploaded to the ALPB manuals page by Admin or Dr. Bob?
Legacy, it's great that your Sony is still working well, I can't think that a lot of portable players lasted, but people may have taken better care of a fine portable like that because of its quality. I know I've been through a few portable headphone radios, and usually the first thing to start going are the headphone jacks, then the volume controls and even the tuner can get static in it and not want to land right on the stations.
I'm glad you're promoting stereo so much on your station, what might be better called an AM stereo revival. Whether or not listeners can hear it on many radios, it still puts across that you care about your sound, especially to the Album Rock audience you have. The people who understand what a 'deep cut' is probably can see the value of stereo. Anyone can appreciate a music station being in stereo, if they hear the announcements, that's expected.
My town had a couple of AMers in C-QUAM stereo in the 1990s, and I noticed that there wasn't a lot of promotion, though one of them did ID as AM stereo regularly. The other said nothing at all. I guess it wasn't promoted because there wasn't much competition between stations then, but if we'd had a few music broadcasters battling, then we would have heard about the stereo feature.
Right radios were built better when they had C-QUAM, like the article shows you want a receiver with low microphonics and phase noise, and an RF amp stage helps too. It seems like most of the stereo decoder chips went into car radios. so when lots of people bought a car in the 1990s, it had the chip. I have two of them, not in cars, but one is a Chrysler, and the other is a Realistic AM/FM cassette.
I wish there was a ten watt allowance on the AM band, under minimal control, experimentation allowed. Only radio experimenters would be likely to use it, and dreamers, the commercial establishment doesn't want to deal with AM. My radical side takes over and says that something should be done. Experimenters started broadcasting, but in a land grab, corporations took over broadcasting when they saw potential in it.
It's the same as now, when corporations have taken control over how people talk to each other on line.
Boomer
|
|
|
|
Post by Boomer on Aug 12, 2018 22:50:40 GMT
WWKB, Stereo?
Anyone here living near Buffalo, New York who has an AM stereo radio, WWKB 1520 seems to be broadcasting in stereo again. They're sports radio, but likely the spots and IDs would have stereo effects.
Listening now by a WebSDR receiver, but it doesn't have stereo decoding.
|
|
|
|
Post by thelegacy on Aug 18, 2018 23:48:42 GMT
I wonder if you could use the Maducci C-Quam decoder with that SDR?
I'm going to update some of my promo's for C-Quam. I'm letting folks know I'm broadcasting in it.
|
|
|
|
Post by Boomer on Aug 19, 2018 2:38:19 GMT
Wow, that's an interesting idea Legacy, I never thought about how a hardware stereo decoder could be used with an SDR. The decoder chips are made to take in an IF signal, and in an analog receiver that's usually 455 or 450 khz, so you'd somehow have to get the SDR to output the received signal at the IF, I'd think. That's a tricky problem.
The decoder chip, like in the Meduci board, needs to be able to lock on an IF frequency signal to make the rest of the circuit work to decode stereo.
Actually there's one SDR software that can do AM stereo, I believe it's SoDiRa, and you can see demo videos of a stereo exciter being received on one, on the PC screen.
The SDR I was hearing WWKB on was heard by logging on to a WebSDR computer on line, and I just heard it in mono.
The solution might be to just have the SDR software do the reception as well as the decoding of stereo, that would be the easiest, and so easy for an SDR to be programmed to do it directly. My knowledge of SDR is primarily just from reading and I'm not well schooled on it yet.
Here's something I'd like to see, a stereo transmitter built with a Raspberry PI, or something like a Nano single board minicomputers.
Boomer
|
|
