Why Do FM Frequencies End in an Odd Decimal?
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Why Do FM Frequencies End in an Odd Decimal?
1–10 of 56 posts
Re: Why Do FM Frequencies End in an Odd Decimal?
#2Did I miss something, or did this not answer the question in it's heading? It basically says it's like this in the US.
Re: Why Do FM Frequencies End in an Odd Decimal?
#3This only happens in the US, probably. The fun fact is that some car manufacturers believe this is global, so they only allow odd frequencies on the car radio.
Re: Why Do FM Frequencies End in an Odd Decimal?
#4Did I miss something, or did this not answer the question in it's heading? It basically says it's like this in the US.
Yes, that's exactly why, because the FCC said to do it that way. There are countless examples of "why is it this way" being answered "because that is what some arbitrary person picked."
My favorite example of this I remember reading in Andrew Tanenbaum's Networking book that the first frequency-hopping protocols used 88 frequencies because that is how many keys there are on a piano:
https://en.wikipedia.org/wiki/Frequency-hopping_spread_spect...
Re: Why Do FM Frequencies End in an Odd Decimal?
#5This only happens in the US, probably. The fun fact is that some car manufacturers believe this is global, so they only allow odd frequencies on the car radio.
We had a radio in our old Chrysler Voyager that required a pretty insane secret code being entered (turning it off and on again 5 times in a row or something like that was part of it) in order to enable to tune to regular EU frequencies...
Re: Why Do FM Frequencies End in an Odd Decimal?
#6Did I miss something, or did this not answer the question in it's heading? It basically says it's like this in the US.
It's the typical "write a lot, but don't really answer anything" style that so many politicians utilize, only substituting "talk" for "write".
The entire section could have been summed up as:
Because each broadcast band is identified by the frequency of the center of the band, the bands begin on an even number, and the bands are two "units" wide, making the center frequency an odd number.
Edit: for clarification.
Re: Why Do FM Frequencies End in an Odd Decimal?
#7Wikipedia¹ has a more interesting answer to "Why?" —
After World War II, the FCC moved FM to the frequencies between 88
and 108 MHz on June 27, 1945. The change in frequency was said to
be for avoiding possible interference problems between stations in
nearby cities and to make "room" for more FM radio channels. However,
the FCC was influenced by RCA chairman David Sarnoff, who had the
covert goal of disrupting the successful FM network that Edwin
Armstrong had established on the old band.
Re: Why Do FM Frequencies End in an Odd Decimal?
#8I had an Aiwa stereo/receiver several years ago that could tune the FM radio in 50kHz increments instead of 200kHz. Most stations were weaker 50kHz off, but a few were stronger. More interestingly, there were one or two stations I could only get on the even decimals, usually between two empty odds. Now I wonder if someone's transmitter was configured incorrectly, or whether it was an illegal broadcast.
Re: Why Do FM Frequencies End in an Odd Decimal?
#9Did I miss something, or did this not answer the question in it's heading? It basically says it's like this in the US.
Yes, that's exactly why, because the FCC said to do it that way. There are countless examples of "why is it this way" being answered "because that is what some arbitrary person picked." My favorite example of this I remember reading in Andrew Tanenbaum's Networking book that the first frequency-hopping protocols used 88 frequencies because that is how many keys there are on a piano: https://en.wikipedia.org/wiki/Freq…
> [Why] the first frequency-hopping protocols used 88 frequencies because that is how many keys there are on a piano
Well, it is a rather arbitrary reason but a valid explanation.
In the case of FM frequencies, the question remains ... why did they picked odd frequencies?
Re: Why Do FM Frequencies End in an Odd Decimal?
#10Wikipedia¹ has a more interesting answer to "Why?" — After World War II, the FCC moved FM to the frequencies between 88 and 108 MHz on June 27, 1945. The change in frequency was said to be for avoiding possible interference problems between stations in nearby cities and to make "room" for more FM radio channels. However, the FCC was influenced by RCA chairman David Sarnoff, who had the covert goal of disrupting the s…
RCA went after Armstrong. They knew that by convincing the FCC to change the frequencies they could seriously disrupt FM and make existing equipment useless. Armstrong later committed suicide. His wife won all of the on-going lawsuits. Basically, RCA broke him financially and mentally with multiple lawsuits and years of "discovery". Armstrong is the father of frequency modulation (FM) and some argue the father of modern radio.