[time-nuts] Tait reference

Charles Steinmetz csteinmetz at yandex.com
Mon Jan 11 06:18:35 EST 2016


Adrian wrote:

>Are these the references with a rubidium oscillator ? They seem to 
>have similar models with OCXOs etc.

Tait is a manufacturer of mobile communications gear in New 
Zealand.  The T801 was part of a discontinued "quasi-synchronous 
communications system" -- a form of simulcasting on the same 
frequency by transmitters at different locations, to fill in dead 
spots.  Tait's application was utility and public service mobile 
radios (not radio broadcasting, where this scheme has also been 
used).  Here is Tait's basic description:

>The Tait Quasi-Synchronous Communication System works by 
>broadcasting simultaneously from several transmitters on the same 
>frequency. The transmitters then operate as a single transmitter 
>giving superior coverage.
>
>A Tait T801 Frequency Referenct Module acurately maintains the 
>frequency of the transmitters at each site.
>
>Where required, the T801 allows small frequency offsets to prevent 
>the occurrence of static nulls in the overlap area.
>
>The T801 module may be driven from one of a number of frequency 
>references, such as:
>-- Rubidium frequency standard
>-- Broadcast frequency standard
>-- Oven Controlled Crystal Oscillators (OCXOs)
>-- GPS Caesium Clock

This suggests that the T801 does not have an internal frequency 
reference, but rather requires a precision external reference to 
function.  (It has a jack labeled "INTERNAL STD OUTPUT," but that may 
simply be a reference that is derived from the external standard, or 
a backup crystal oscillator to keep the transmitter more or less on 
frequency if the external reference signal is lost.)

Best regards,

Charles





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