WLLH-AM Lawrence Facility To Remain Silent For A While

Garrett Wollman wollman@bostonradio.org
Sat May 5 23:32:09 EDT 2007

<<On Sat, 5 May 2007 22:44:23 -0400, "Dan Strassberg" <dan.strassberg@att.net> said:

> Because of the great improvements over the last 75 or more years in the
> frequency accuracy and stability of crystal oscillators, most synchronous AM
> operations (and there are probably several dozen in the US in addition to
> WLLH) no longer use special equipment to lock the transmitter frequencies
> together. Instead, the only thing special in most cases is the selection of
> crystal pairs that are well matched in frequency and whose frequencies have
> been shown to behave similarly versus temperature, power-supply voltage, and
> time.

Many modern transmitters are designed to be phase-locked to UTC(GPS)
(and ISTR that this is a requirement for IBOC); I would expect that
even having a particularly good crystal is no longer required, so long
as the GPS (or IS-95 cellular base station) signal is reliable.


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