[time-nuts] Austron PRR-10 GPS discliplined Rb...

[Rob Kimberley]

I remember them well...

Have sold them and installed them for Telco customers in Europe when I
worked for Datum in the mid 90's. Novel design, and as you say they don't
attempt to correct the Rubidium, but compare its output against GPS and use
DDS to make the correction. In practise they worked very well and provided
excellent Stratum 1 references.

Unfortunately I don't have any documentation, but have some of the blanking
panels and other bits of hardware lurking in the store room here. Will have
a hunt around, and see exactly what's available to anyone interested.

You got yourself an excellent bargain!

Rob Kimberley 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of David I. Emery
Sent: 26 January 2007 22:23
To: time-nuts at febo.com
Subject: [time-nuts] Austron PRR-10 GPS discliplined Rb...

	I snagged (for $150 BIN, which might have been too much) a
Datum/Austron PRR-10 Stratum 1 Timing receiver complete with a LPRO Rb...
and two channels of GPS receiver/timing board (redundant, hot swappable).

	These things use the Motorola Oncore family timing receivers (the
latest version (rev G firmware) can support the M12M+) and are primarily
intended to supply precise timing for telco networks as DS1 or
E1 output signals with all the right bits set for timing purposes.

	There is a 4 channel "analog" output board available that can supply
10 mhz, 5 mhz and 1 mhz (I found one of those too), but the primary outputs
in usual units one finds in the field/surplus are the
DS1 or E1 variety.

	The interesting thing about these units (which ceased production in
July 2005 - possibly because of the abandonment of the Oncore receiver
family by Motorola) is that they are the second kind of GPS disciplined
clocks - namely phase microstepper based designs which accept a reference 10
mhz input and use a DDS chip to create a phase rotated and frequency
corrected version which is used to phase lock a 20
mhz VCXO and from that generate a new 10 mhz and 1 PPS.    This is in
distinction to the Lucent RFTGs which adjust the C field of the LPRO RB to
phase lock it to the 1 PPS input.

	Apparently the firmware measures the frequency offset of the 10 Mhz
reference input (in my unit generated by a LPRO 101) and its behavior over
time and temperature and uses this to generate a phase step correction for
the DDS which results in a precise 10 mhz output and
1 PPS used to compare with the GPS timing receiver 1 PPS and adjust the
correction and its derivatives over time for optimum tracking.

	This means they can take a slightly off frequency but stable 10 mhz
and make a precisely on frequency and even more stable 10 mhz locked to GPS
when GPS is available and open loop corrected  to the last GPS offset values
when GPS is not using both  measured frequency offset and change of
frequency offset with time (and I think temperature).

	I have a users manual (circa 2001) in .pdf format, but would dearly
love to find a source of more detailed documentation - the things are full
of jumpers and stuffed/not stuffed options and it would be nice to know much
more about them.

	They do, however, provide some ADEV data on the quality of the input
source as one of their data outputs available from the RS-232 port and as
such are kind of neat...
	
	
-- 
   Dave Emery N1PRE,  die at dieconsulting.com  DIE Consulting, Weston, Mass
02493 "An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole -
in celebration of what could have been, but wasn't and is not to be now
either."


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