It's kind of like the Beta Max v.s. VHS type of thing. When something is relatively new what standard do you choose? There is probably more too it than that such as politics and FCC decisions on band alocations. Usually when something new comes out there are a variety of ways it can be executed. Each way has a set of advantages and disadvantages. If you look at the progression of electronics you will see differing viewpoints such as: The battle over DC v.s. AC power distribution (Edison v.s. Tesla). Radio wavelength v.s. frequency as indicators on your radio dial. CB channel allocation 23 channels v.s 40 channels. Which color TV system do you choose i.e. do you go for compatability with black and white televisions or do you adopt a system that favors color TV. The list could go on and on, somewhat like my posting, but I hope you get my point. Now the 49 Mhz band is allocated for two way radio, remote control devices and some cordless phones. I am sure there are others with a more complete knowledge on the history of FM. Hopefully they won't cringe at my attempt at historical (hysterical) explination.
As a side note, FM was developed long before it was made commercially available to the public. In some of my old magazines from the early 30's the writers would often use plumbing analogies to explain the workings of AM and FM.....is that where leaky condencers come from?
MRO
There's an interesting story behind the old FM 40 band.
To make a long story short, Edwin Armstrong, the inventor of FM radio was granted the FM 40 frequency band by the FCC in the 1930s. After WWII, the FCC decided that television sound was to utilize FM so they reneged on the 40 band in favor of TV sound and sent FM radio to the 88 - 108 band we have today.
This decision rendered existing FM receivers obsolete and set the format back decades (FM didn't fully recover 'til the 1970's).
Zenith took the high road and produced receivers with both FM bands during the transition period. Zenith's Tone Register table top model is one of the better-known examples. They afforded listeners the option to tune in to all FM stations during the transition.
While often available on online auction sites, dual FM band receivers in original, pristine condition are becoming scarce and are highly prized by collectors.
Hope it helps.
Folks, correct me if I'm wrong... I'm an old dog and tend to forget things, LOL.
If I recollect correctly, the FM 40 band was slated for TV channel 1 or an emergency public alert TV broadcast system. It was never put into service. This explains why TV channels went from 2 - 13. Again, I may be a bit off-track...
On a side note, some tube FM receivers are capable of tuning in resonant signals that the their solid state counterparts will not. I've picked up nursery monitors, TV sound and early cordless phone transmissions with an old Eico FM tuner just by tinkering with the length of the antenna wire. A nursery monitor is like a bug or hidden mic in the house. Many people don't realize that.
Hope it helps.