In standard old broadcast television, the frequency bands in which stations can transmit have long been identified by simple, small integers — these being the TV “channels” of course. You can see a table of them here. This plan made the TV set’s user-interface nice and easy to understand for Joe Sixpack, his wife, and his 2.3 children. (And Lord knows the 0.3 child had enough to contend with already.) He could then dial his TV to a straightforward Channel 6, not an obscure “85 MHz”, for example.
But ordinary broadcast radio has no channel numbers, at least not in the US. (Radio for emergency services, and CB radio, may be different.) Normal radios all have tuners that use “naked” frequency scales, in both AM and FM, and the stations also self-identify by frequency. That’s a little odd, seems to me. I would have thought — certainly after television became popular in the 1950s, and before FM radio took off in the 60s — that the FCC or the public at large would have gravitated to a channel-based system, particularly in FM radio.
Or not. It’s possible I’m overestimating the appeal of channel numbers. Or maybe such a thing was tried already and it fizzled. Speaking as a techie, I don’t mind the naked frequency values myself, but I’m thinking here about Joe Sixpack, who cares about tuning in to the right station, not learning technical trivia about broadcast standards.
the stations are allowed frequencies in set intervals (AM 10kHz, FM 0.2 MHz) and there are channel numbers for each used by the FCC but not much by anyone else.
Commercial radio bands have stations assigned frequencies that are evenly spaced across the band. TV signals have been allocated in non-contiguous groups and some channels are not evenly spaced. Also, spaces between some channels are non-TV allocated areas devoted to quite different services.
That makes it easy to design a radio with continuous tuning within one band, but difficult to do the same for TVs. It’s not important for a user to know that channel 6 is not followed by channel 7 in the spectrum just as long as the TV tuner goes to the right frequency. Simple channel numbers make it easier than complicated frequencies.
In the very early days of broadcast AM radio, stations identified their location not by frequency, but by wavelength. This practice continued in the Soviet Union and Eastern Europe up until just a few decades ago. Also, in the early days of broadcasting, frequencies weren’t as fixed or regulated as they are now.
FM radio in the US has channel numbers (Channel 200 at 87.9 MHz, Channel 300 at 107.9 MHz), but they’re not used by anyone but the FCC. I don’t know what happened to Channels 1-199. I’ll make the assumption that broadcasters never used channel numbers in broadcasting or station promotion, because they could be confused with television channels.
The first TV I remember my folks having was a Dumont and it had continuous tuning with a marked dial. Channels 2 through 6, then a gap with police calls and such, then 7 through 13. The channels were marked on the dial, but it was up to the user to get it tuned correctly. Of course there was a magic eye to help you get it right. This was in the early 50’s.
You would have needed to be able to tune into nearly 100 channels to get the full AM spectrum. Most people would have a harder time remembering that they got channels 5, 23, 38, 44, 62, 78, and 98 and be driven crazy trying to tune across 100 clicks. Actually, it would be even worse since larger cities might have 20 radio stations but only three tv stations. When UHF started taking off with channels 14 to 83, no owner wanted any numbers out of the teens because people weren’t willing to click that far.
Whether it was even technically feasible to make ordinary inexpensive radio sets in the 20s and 30s that could click to 100 frequencies is doubtful. But by the time it was, radio frequencies were ingrained in habit. Television started fresh in the 1940s and FM radio was a minor appendage until the late 60s.
The reason is the way AM radio developed. In the beginning radios were kits. As you know you don’t even need electricity to get a radio station, of course you have to have a pretty big amplifer to hear the signal.
Radio stations weren’t regulated at first and they would be bouncing all over the place. More to the point, the engineers weren’t careful about what frequency they were at. So the government eventually got to the point where they formed the Federal Radio Commission, the predecessor of the FCC.
These people assigned frequencies. Since newspapers already were publishing the frequencies where people could tune in, it made no sense to rename them with channel numbers.
But AM became a mess quickly. Every politician wanted his own AM station in his town. WLW even was allowed for awhile to go to 500,000 watts. (Yes FIVE HUNDRED THOUSAND). The FCC kept saying that AM would run out of room, but it never did, because the band was filled by politicans passing rules to allow stations to run directional antennas or to run at lower power at night (AM travels further at night).
So basically if some engineer could figure out how to put an AM station on an unoccupied space, by using a directional antenna or signing off at night, he was able to get it passed through.
When FM and TV came along the FCC wanted to avoid this and allocated channels to them so that only so many stations would be in the USA. The FM band was moved twice so the channel system couldn’t take hold. And the TV channel system was also reassigned twice.
Eventually TV lost channel 1. Then it lost 14-20 (Only in the largest cities where there were no stations. Stations in large cities already on the air were allowed to stay. This is why Chicago was assigned channel 20 and 14 and lost channel 14 but kept channel 20). Channels 70-83 were also lost.
Today TV channels have virtually no meaning with digital TV as most (but not all) TV statins don’t broadcast on the channel they advertise. For example, WGN-TV Channel 9 is actually on channel 19 but through the use of something called PSIP shows up as a virtual channel on channel 9
Obviously, Markxxx never had a crystal radio. You got the right kind of crystal connected to a radiator and a “cat’s whisker” connected to an earphone and there you were, no electricity at all. Of course, there was a bit of electricity, the power inherent in the signal.