Hi to u all,
some time ago i read an old american electronics magazine about a novel circuit developped by a CBS engineer to ameliorate the fm stereo standard.The signal to noise ratio is usually worse for a stereo signal than a mono one.ratios of usually 60dB to80dB is the norm.however the fmx stereo claims almost a 80dB figure with some add up electronics.unfortunately the article was on a two magazine span and my friend didn't have the second part.so has anyone heard about that technique and what was its outcome.american readers,can you help?thanks
some time ago i read an old american electronics magazine about a novel circuit developped by a CBS engineer to ameliorate the fm stereo standard.The signal to noise ratio is usually worse for a stereo signal than a mono one.ratios of usually 60dB to80dB is the norm.however the fmx stereo claims almost a 80dB figure with some add up electronics.unfortunately the article was on a two magazine span and my friend didn't have the second part.so has anyone heard about that technique and what was its outcome.american readers,can you help?thanks
Google turns up tons of stuff for FMX stereo; have you skimmed that?
Does this "old american electronics magazine" have a name and a date?
American Radio History: A century of documents about Broadcasting, Radio,
TV and Electronics
Does this "old american electronics magazine" have a name and a date?
American Radio History: A century of documents about Broadcasting, Radio,
TV and Electronics
To PRR,
The magazine is no more in my friend's possession but it could be popular electronics.i don't remember well.I have gone to the american radio sites to find out but there is so much documentation and i really don't have the time to go through all these.but can you tell me if you have come to use the fmx yourself and what is your opinion on the system.I understand after reading wikipedia that two schools of thought were opposing themselves on the matter.it would be of great interest to know if the technique was good indeed from practical users and why if the fmx stereo was an improvement on the signal to noise ratio did it failed to make an impact on hifi manufacturers.
The magazine is no more in my friend's possession but it could be popular electronics.i don't remember well.I have gone to the american radio sites to find out but there is so much documentation and i really don't have the time to go through all these.but can you tell me if you have come to use the fmx yourself and what is your opinion on the system.I understand after reading wikipedia that two schools of thought were opposing themselves on the matter.it would be of great interest to know if the technique was good indeed from practical users and why if the fmx stereo was an improvement on the signal to noise ratio did it failed to make an impact on hifi manufacturers.
I knew nothing about FMX so I read the Wikipedia article. It seems clear enough to me. It says how it worked, how it was criticised, and why it failed commercially. To know more you would need to read original sources, which you say you don't have time to do.
It is unclear why you feel that you might get a definitive answer to a controversial technical argument from 30 years ago by asking a question on this forum.
It is unclear why you feel that you might get a definitive answer to a controversial technical argument from 30 years ago by asking a question on this forum.
Fmx stereo
To DF96,
Just to know if anyone has come to test the system and know about their own experiences other than that depicted in the article.When i a was a kid i would spend hours orienting two fm antennas which fed an Akai reciever provided with two antenna inputs.The receiver was a very special unit with Dolby FM and other controls to get the best of reception.my knowledge in technical matters was scant then and i couldn't understand why some programmes could not be received in stereo how hard i tried to orientate the antennas.Unfortunately for me ,my uncle,the owner of the Akai sold all his hifi equipment before moving to Australia.It would be years afterwards that i would buy my first tuner a Yamaha which inspite of a multitude of ics inside could not match the sound quality of the Akai.
To DF96,
Just to know if anyone has come to test the system and know about their own experiences other than that depicted in the article.When i a was a kid i would spend hours orienting two fm antennas which fed an Akai reciever provided with two antenna inputs.The receiver was a very special unit with Dolby FM and other controls to get the best of reception.my knowledge in technical matters was scant then and i couldn't understand why some programmes could not be received in stereo how hard i tried to orientate the antennas.Unfortunately for me ,my uncle,the owner of the Akai sold all his hifi equipment before moving to Australia.It would be years afterwards that i would buy my first tuner a Yamaha which inspite of a multitude of ics inside could not match the sound quality of the Akai.
Fmx stereo
To Juergen knoop,
Perhaps i made myself misunderstood.i know that every fm station use a compression technique prior to broadcasts and that the receiver must have the dedicated circuits to be able to receive the programmes.The fmx stereo was developped in the us,so my initial questions was addressed to these people who,old timers,have come in the past used that technique.I just wanted to know their impression about the sound quality and if it was effectively what was depicted in the report.Although the zenith stereo system was chosen by the fcc,some articles in eleçtronics magazines said that there were better systems ansd because of poor marketing were let down.
To Juergen knoop,
Perhaps i made myself misunderstood.i know that every fm station use a compression technique prior to broadcasts and that the receiver must have the dedicated circuits to be able to receive the programmes.The fmx stereo was developped in the us,so my initial questions was addressed to these people who,old timers,have come in the past used that technique.I just wanted to know their impression about the sound quality and if it was effectively what was depicted in the report.Although the zenith stereo system was chosen by the fcc,some articles in eleçtronics magazines said that there were better systems ansd because of poor marketing were let down.
Be aware that the compression now used routinely by FM stations and the compression used by FMX are two completely separate issues and must not be confused.
The Zenith-GE stereo system was chosen because it combined the best parts of the Zenith and GE systems, which were similar but not quite identical. The result is simple to encode and decode, although it does suffer from the noise problem when signal strengths are weak.
The Zenith-GE stereo system was chosen because it combined the best parts of the Zenith and GE systems, which were similar but not quite identical. The result is simple to encode and decode, although it does suffer from the noise problem when signal strengths are weak.
Virtually every FM station I'm interested in is webcast and in some cases like Howie's WXYC are better than any over the air broadcast. There's also the issue that I can listen live from San Francisco to Boston and actually call in requests.
In 1961!
FMX was a 1989 idea. It sits "on top of" multiplex FM
The Story of FMX, a Wannabe Radio Standard That Was Killed in a Very Public Way - Motherboard
A real test for CES, on-air, blind, caused great outrage due to degraded sound for many non-FMX listeners. Bose (who was incidentally working on a different scheme) exposed the reason why FMX did not work in real life as nice as it did in CBS Labs.
If it is not *encoded* FMX, it can do you no good even with an FMX radio. Nobody ever broadcast FMX except that 1-week experiment.
Straight FM is clean up to a point and then degrades very quickly. Stereo multiplex FM is a lower-tech added audio channel on top of the mono FM and degrades before the mono does. FMX attempted to "boost" this added channel, but apparently suffered worse with multi-path, which is common in urban areas.
Your location shows as "mauritius,indian ocean". I actually found a list of stations on that island. 8 FM stations (on 21 carriers). That's more than I have here. I understand marginal FM reception: the four local stations literally play the same pap on monthly rotation. Steven King's station is different but over the mountains so comes in poorly (and is sometimes "too different" even for me).
It appears that several of the radio stations and a few online-only sources target the Mauritian audiences with on-line streaming and, if their servers are on-island, should be technically excellent (if they have competent techs). For lurkers: Mauritius is 1,000+ miles out in the Indian Ocean and, despite massive ICT development, may not be the best place to pull high-quality audio from off-island. (Or maybe: it is on the long route from America/Europe to the Far East, and it looks like the new fat cable lands at Mauritius; I dunno if they tapped it.)
No, nothing whatsoever to do with other analogue media.revenant said:
The reasoning, as fas as I understand it, was that FM will be replaced by DAB. DAB is better because it is digital (they said), and it costs too much to keep two broadcast methods running in parallel. In reality, DAB is unreliable (for technical reasons to do with the frequency band chosen) and low quality (because of political/commercial decisions taken to use low bit rates and so provide many stations all sounding the same). The BBC has now discovered that many of its listeners are happy with FM and do not intend to convert to DAB. Such listeners also do not wish to use the internet for 'radio' listening, so they had a choice between abandoning the listeners or abandoning the FM switchoff. Abandoning the listeners also would mean abandoning the main justification for a universal licence fee, which is how the BBC is funded. Someone high up in the BBC has finally realised this.
FM - what about mobile radio listeners (car drivers) in general.
Afaik the mobile internet/cellphone network coverage still isn't up to the existing level of old-school FM radio and isn't going to be unless they drastically change the freq. bands which I doubt is going to happen.
Radio is a different medium compared to TV, where a switch to digital is easily enforced by subscription models etc.
Afaik the mobile internet/cellphone network coverage still isn't up to the existing level of old-school FM radio and isn't going to be unless they drastically change the freq. bands which I doubt is going to happen.
Radio is a different medium compared to TV, where a switch to digital is easily enforced by subscription models etc.
Probably around the FMX time, National made some chips like LM4500, that could blend down the stereo separation to try to keep signal to noise up, as signal strength degraded.
I wonder if that was in response to the FMX issues? Also, they had DNR ( Dynamic Noise Reduction ) about that time; that actually made it into some radios, at least I had a car radio with DNR in it.
Both of these required no encoding at the broadcaster.
Win W5JAG
I wonder if that was in response to the FMX issues? Also, they had DNR ( Dynamic Noise Reduction ) about that time; that actually made it into some radios, at least I had a car radio with DNR in it.
Both of these required no encoding at the broadcaster.
Win W5JAG
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IIRC Carver had something that reduced stereo separation to the benefit of SNR also.
Hope they learned from us... DAB only on NRK channels (roughly the Norwegian equivalent of BBC). The sound quality is worse, and when you get a drop in signal strength it cuts out clean, not like FM where you still heard what was said only more noisy.
Another vote for internet radio. Even in the car.
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