AM STEREO DECIDER

Everything technical about radio can be discussed here, whether it's transmitting or receiving. Guides, charts, diagrams, etc. are all welcome.
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rigmo
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AM STEREO DECIDER

Post by rigmo » Sat Oct 07, 2023 10:00 pm

Hi
Question
Albert H an all. Do you heave good AM STEREO DECODER?
What is better MC13020 or MC13028?

http://meduci.com/
https://rf-circuit-schematic.blogspot.c ... 13028.html
http://www.aspisys.com/dqam_manual.pdf
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Albert H
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Re: AM STEREO DECIDER

Post by Albert H » Sun Oct 08, 2023 3:24 am

None of them - they're all horrible! AM stereo was never more than a silly gimmick, which never really took off. The biggest radio markets around the world were moving to AM for talk stations and FM for music, so AM stereo largely died out.

The American channelling on MW - 10 kHz - gives a chance of slightly better sounding audio, but in Europe, the 9kHz spacing makes audio bandwidth a bit tighter. AM stereo also uses a wider channel width, so would have been impractical in Europe because of the high numbers of stations (at the time) crammed into a limited number of possible frequencies.

AM also has the interference problem. FM invariably sounds better because as long as the signal strength is enough, the limiting action of the IF strip in the average FM receiver will eliminate most interference signals. AM, on the other hand, is prone to all sorts of pops bangs and crackles....

To quote Steely Dan: "FM, No Static At All"!
"Why is my rig humming?"
"Because it doesn't know the words!"
;)

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Zozo
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Re: AM STEREO DECIDER

Post by Zozo » Mon Oct 09, 2023 5:50 pm

Ultimately Motorola's C-QUAM has the largest populatiry when it comes to Stereo-AM. Even Dreamradio AM in the Netherlands only upgraded to stereo on 1485KHz in February last year; They also opted for C-QUAM encoding.

I have a few Stereo capable AM receivers I purchased from a Japanese auction site which is the best option in my option, rather than modifying receivers with decoders. However the Meduci has the largest support / help docs I'd say.

Stereo-AM is still largely used in the United States, Canada and Australia. However there are still some in the following countries: Philippines, Japan, Thailand, South Korea, Italy & Brazil.
Give me a AM transmitter with things that glow any day.

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Zozo
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Re: AM STEREO DECIDER

Post by Zozo » Mon Oct 09, 2023 6:02 pm

This video is a direct feed from the receiver, you can certainly hear the separation.

Give me a AM transmitter with things that glow any day.

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Re: AM STEREO DECIDER

Post by fmuser877 » Mon Oct 09, 2023 7:05 pm

I wonder if DAB+ stereo will be better nowdays

Albert H
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Re: AM STEREO DECIDER

Post by Albert H » Mon Oct 09, 2023 9:33 pm

fmuser877 wrote: Mon Oct 09, 2023 7:05 pm I wonder if DAB+ stereo will be better nowdays
Not really. I've recently put a number of DAB+ stations on the air, and the audio quality is generally disappointing - mostly because the distribution companies are trying to cram ever more stations into their limited bandwidth.

Theory suggests that - assuming you have a good sample rate - that the quality of DAB+ should be close to that of a CD, but in reality the coding and decoding process is less than perfect, and a quick test we tried was to have the same material played direct, on FM stereo, and on DAB+. We had a bunch of listeners - in the same listening room - fill in a chart with the mode that they thought each music snippet was being played by....

All of them could identify the DAB+ almost every time (91%), FM Stereo about 40% of the time, and direct CD about 60% of the time. The digital artefacts of the DAB+ coding process are almost always audible.

A while ago, we tried some similar listening tests with various different audio encoding schemes, including WAV, AAC, FLAC, Ogg, MP3 and Dirac. ALL of them were reasonably obvious, but when we asked for preferences, our panel usually chose WAV or FLAC, with higher bit-rate Ogg not too far behind!

We ran a similar set of tests with broadcast professionals at an EBU meeting in Geneva, and everyone chose FLAC and WAV as their preferences. All of them could (usually) identify the codec they were listening to!
"Why is my rig humming?"
"Because it doesn't know the words!"
;)

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Re: AM STEREO DECIDER

Post by Albert H » Mon Oct 09, 2023 9:37 pm

Zozo wrote: Mon Oct 09, 2023 6:02 pm This video is a direct feed from the receiver, you can certainly hear the separation.
Unfortunately, it's NOT actual broadcasting you're seeing - it's a little AM Stereo exciter connected directly to the receiver. Unfortunately, in the Real World™, the vagaries of AM make the results rather less than acceptable listening quality! Most of the broadcasters in the USA that tried it abandoned it as their music services left AM. It's pointless for talk shows!
"Why is my rig humming?"
"Because it doesn't know the words!"
;)

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