When the original FM channels were first allocated, most receiver’s and transmitters were tube affairs. Many transmitters had crystals in “ovens”. These were temperature sensitive. There was a “filament” switch which you had to turn on for at least 15 minutes before “sign on” or you would get crazy readings if the transmitter would even come on. The FCC had you fill out a transmitter log every 30 minutes or an hour.* One of the readings was frequency drift.
Now you have FM 2 way communication radios on 12.5 KHZ channels. It should not be too hard for 60 KHz channel to contain two 15Khz analog audio (stereo) and RDS. The old VHF channels were 15 MHz. In theory there are 250 60 KHz “channels”. If you had a channel adjacent spacing that gives you 125 channels. A semi smart radio should be able to tell the difference between TV and Radio signals using RDS. In the analog days, you could not have adjacent VHF channels in the same market. Most markets should have one of the old channels 2 thru 6 “open”. I contend a “smart” receiver could figure out where radio stations are on the old analog VHF channels 2 thru 6. Most typical digital TV sets can find UFH and VHF stations so just tuning 54 MHZ thru 108 MHZ analog audio should not be impossible.
*It’s been over 40 years and sometimes I forget some of the details.
Now you have FM 2 way communication radios on 12.5 KHZ channels. It should not be too hard for 60 KHz channel to contain two 15Khz analog audio (stereo) and RDS. The old VHF channels were 15 MHz. In theory there are 250 60 KHz “channels”. If you had a channel adjacent spacing that gives you 125 channels. A semi smart radio should be able to tell the difference between TV and Radio signals using RDS. In the analog days, you could not have adjacent VHF channels in the same market. Most markets should have one of the old channels 2 thru 6 “open”. I contend a “smart” receiver could figure out where radio stations are on the old analog VHF channels 2 thru 6. Most typical digital TV sets can find UFH and VHF stations so just tuning 54 MHZ thru 108 MHZ analog audio should not be impossible.
*It’s been over 40 years and sometimes I forget some of the details.