Author Topic: 1962 Magnavox Astrosonic Stereo Theatre  (Read 3675 times)

amglow

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Re: 1962 Magnavox Astrosonic Stereo Theatre
« Reply #45 on: August 16, 2018, 08:39:16 PM »
The MPX decoder was an add on for early 1960's FM tuners to allow the tuner to decode the two separate channels from the transmitted FM signal.  Many companies built in the option to plug in an external MPX decoder so one can easily update their current tuner after the FCC picked a decoding standard.  The FCC, in 1961, chose an MPX decode standard for stereo FM broadcasting in the United States.  All later tuners now have the MPX decoder built in to the FM tuner.
Paul

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Re: 1962 Magnavox Astrosonic Stereo Theatre
« Reply #46 on: August 16, 2018, 08:54:35 PM »
So,
What happened before they were able to decode the two signals? Sound only play out of one aero of speakers or was the FM signal not as strong?

amglow

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Re: 1962 Magnavox Astrosonic Stereo Theatre
« Reply #47 on: August 16, 2018, 09:06:45 PM »
There was no two-channel FM broadcast prior to 1961.  Everything was monophonic.  Even today if you have a mono FM broadcast tuner, it will decode embedded data as one combined audio signal.  A tuner with MPX decoder will decode and separate the audio to its requisite left and right channels.
Paul

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Re: 1962 Magnavox Astrosonic Stereo Theatre
« Reply #48 on: August 16, 2018, 09:57:43 PM »
Oh! I understand now. Thank you for clearing that up for me.

walyfd

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Re: 1962 Magnavox Astrosonic Stereo Theatre
« Reply #49 on: August 17, 2018, 04:22:16 AM »
"Stereo" FM was simulcast prior to 1962.  It only works on units with both an AM and FM tuner.  Stations would, and sometimes only at certain times of the day, air one channel on their AM band and the other channel on their FM band. 

So you set it to AM-FM and one channel, like the one coming in on AM, was heard on the left speaker and the FM channel on the right...

I tried it on my Fisher.  We have a local talk radio station that airs on both bands and it was kinda stereo...