Re: WLLH-AM Lawrence transmitter off-air

[dan.strassberg@att.net]

Synchronizing FM Transmitters is a whole different 
subject from synchronizing AM TXs. By definition, the 
frequency of an FM carrier is not constant; the program 
content modulates the carrier frequency--that's why the 
modulation technique is called frequency modulation. FM 
receivers exhibit a characteristic called "capture 
ratio." When the receiver picks up multiple carriers on 
the channel to which it's tuned, within the limits 
defined by the capture ratio), the receiver locks onto 
whichever signal is strongest.
>
 I realize this is a tad different but might interest some people in the area of
> frequency synchronization ... The Mass State Police's new 800 Mhz trunked radio
> system has multiple synched transmitters working together all over the State.
> Now these are are FM transmitters connected by a large statewide microwave
> system so the charistitics are a little different but the transmitters frequency
> stabilization is controlled with some sort of GPS system. When you are between
> two of them you hear kind of a mobile flutter kind of sound but with more of a
> regular pattern.
> Some sites that explain the Trunk are at:
> 
> http://lynx.dac.neu.edu/s/stjohnso/ematrunk/msp/msp.html
> http://24.128.24.108/massstate.ram
>