UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

G6Tanuki · 30th Apr 2021, 7:06 pm

Yes, some US FM stations used subcarriers to carry 'elevator music' for use in motels, supermarkets and similar.

I spent 6 months working with a bunch of Honeywell techies in Dallas/Fort-Worth back in the early-80s and one of them had built a subcarrier-receiver using one of the LM56x PLL decoder chips to extract this.

Practically, I've always thought that FM is really just a variant of SSB with a 90-degree-shift; in times-past there were FM-detectors using strange valves [EQ90 Nonode?] that used this approach.

30th Apr 2021, 7:06 pm	#25
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: DX FM reception. Yes, some US FM stations used subcarriers to carry 'elevator music' for use in motels, supermarkets and similar. I spent 6 months working with a bunch of Honeywell techies in Dallas/Fort-Worth back in the early-80s and one of them had built a subcarrier-receiver using one of the LM56x PLL decoder chips to extract this. Practically, I've always thought that FM is really just a variant of SSB with a 90-degree-shift; in times-past there were FM-detectors using strange valves [EQ90 Nonode?] that used this approach.