[time-nuts] Tait reference

Stephen Tompsett stephen at tompsett.net
Mon Jan 11 14:12:40 UTC 2016


The T801 units I have seen in the UK contained a rubidium 10MHz reference
(FRS form factor) and a synthesizer that could produce several outputs of a
nominal 12,8MHz, but which could be individually offset slightly to allow
for precise offsetting of the transmitter frequencies by a few Hz for use
in a quasi-synch PMR system.

On 11 January 2016 at 11:18, Charles Steinmetz <csteinmetz at yandex.com>
wrote:

> 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
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Stephen Tompsett



More information about the Time-nuts_lists.febo.com mailing list