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> [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
by bnegreve 13y ago
> [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?
- coin 13y agoThe frequency is the center of a 200kHz channel. The first channel is 88.0 - 88.2 MHz, thus the center is 88.1.
- TallGuyShort 13y agoAs they say, "The center frequency is located at 1/2 the bandwidth of the FM Channel, or 100 kHz (0.1 MHz) up from the lower end of the channel." It's natural to pick a range between round numbers. so 88.0 MHz - 108.0 MHz doesn't seem so strange a range to be allocated. Now if one band starts at 88.0 MHz and needs 200 kHz of bandwidth, it's going to go from 88.0 MHz to 88.2 MHz. The carrier frequency will be in the middle of this band, so it's represented as 88.1 MHz.
- qbrass 13y ago>Well, it is a rather arbitrary reason but a valid explanation. It's not exactly arbitrary, it was inspired by a player piano, and the original patent used piano rolls. Using all of the keys just makes sense in that context.