User talk:Mofelix2

These FM systems are unique in that they have a ratio of carrier to maximum modulation frequency of less than two.(Contrast FM audio broadcasting where the ratio is around 10,000.) This type does not seem to have any other use and so after 50 years, it seems likely to die out. Consider for example an 6 MHz carrier modulated at a 3.5 MHz rate; by Bessel analysis the first sidebands are on 9.5 and 2.5 MHz, while the second sidebands are on 13 MHz and (-1) MHz. The meaning of "negative sidebands" has never been clarified but the practical result is a sideband of reversed phase on +1 MHz; on demodulation, this results in an unwanted output at (6 - 1) = 5 Mhz.The system must be designed so that this is at an acceptable level. An interesting way of looking at this problem is "It takes time to measure frequency and it takes an infinite time to achieve absolute accuracy"

: "FM Systems Of Exceptional Bandwidth" Proc. IEEE vol 112, no. 9, p. 1664, September 1965 Mofelix2 (talk) 04:59, 28 September 2008 (UTC)