I agree, it's good to use any possible technology to the max, it's always good to care and be proud of offering quality sound to listeners. It's also something to promote being in stereo on the air, and might get a few listeners.
What could be driving the increase in stereo AM stations could be those who run music formats with stereo on their FM translator, meaning they already would have stereo audio in their studios.
There are a few issues to work with, like a station having or getting a stereo exciter. There are old exciters from the 1980s and '90s that can be had for a low cost, but might have to be tuned up, recapped. Some transmitters have stereo generator cards in them.
Another thing to do is make sure the antenna system is tuned well, especially with directional arrays, and shorter antennas that are allowed today, that may have less bandwidth.
Let's hope that more receivers are built, it should be easy to add to DSP chip radios, anything that uses I/Q (In-phase / Quadrature) decoding could be programmed for AM stereo. SDRs can do it already, in their software, I know of one so far, Sodira.
I just got into Software Defined Radio and have a few files to share from my stereo reception journey. The first is WDGY 740 AM from Minneapolis. First is the link from the article you posted, recorded on an AMAX Walkman:
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archive.org]
I have my own reception, using the 'Bikedork' online KiwiSDR from Minneapolis. I tuned in WDGY there, switched to I/Q mode, and recorded that with the Kiwi's recorder. It's a wav file, that I then opened in Sodira set for C-QUAM AM stereo decoding. Even with the signal level, and audio response restriction of the Kiwi, and the steps taken to decode it, you can still hear the stereo.
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boomerthedog.com]
Next is my own Part-15 carrier current station, through a generic RTL-SDR USB stick that cost around $20.
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boomerthedog.com]
You can consider that to be 'best case' reception at high signal levels, but it shows what could be possible close to a station.
SDR frees us from narrow band IFs!
Boom
