Lucent KS-24361 HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A low cost GPSDO system


I  Recently found  a couple of Lucent RFTG  at less than  200$, always on eBay ,from a stock in California. These Redundant Frequency and Time Generator, or RFTG were used in big Cell stations to provide high frequency standards.  it’s also available the “yellow tuna” type, the RFG-RB, that is of course more expensive and it comes with rubidium instead of OCXO. These units mount one OCXO MTI 260 each ,an ultra high stability/high reliability Oven Controlled Crystal Oscillator (OCXO) with a thermal stabilities from 2.0E-010 to 4.0E-009 over a 100°C temperature range with a frequency of 5.000MHz , rivaling , as they say , Rubidium atomic clock performance.They are designed for STRATUM 2, 3 time reference servers. The RFTG -1 unit has a GPS antenna and an internal receiver , (OnCore Motorola) , and the DOCXO 5 MHz(x) is multiplied in 10Mhz in REF-1 and 15 Mhz in both. There is also an output level regulator , you can switch between 17 and 23 db .Maybe in another future test i’ll be able to see phase noise in both outputs. This is the MTI 260 inside both units.


They comes with the Z3809A cable (a rs422 type) to connect both units.In theory , once the Ref-1 units see some GPS should correct the OCXO and the 10 MHz / 15 MHz output on the Ref-0. For now, I’ve tried to power them with 24v 4 Ah for both , using Pin 1 and 2 of the two P1 ports, after GPS antenna and interface cable were connected. The Z2809A cable indeed was just oxidized and wasn’t able to run properly the units. (Thanks Shaun Merrigan )So after just connecting and disconnecting the cable for a dozen of time to remove pin’s residual oxidation, the RFTG just locked under 3 minutes..with yellow standby led on the RFTG-u REF-1 and the green on the primary REF-0 units. The unit has 1PPS on pin 5 on J6 and doing RS422 to RS232 hack as described on Febo :

RFTG          PC

DE-9P         DE-9S

7 <----------> 5

8 <----------> 3

9 <----------> 2

and connected to a normal serial – USB converter from the J8-Diagnostic port , was able to get data flow from Lucent. Tried with two different software under windows xp and both were successful. First with Symmetricon SATSTAT software :

SATCOM2and then with HP GPS Control Program.

SATCOM1I’ll run some other test on this units, maybe i’ll be able to connect it to a FreeBSD server to create another Stratum 1 and also have a deeper look to the HP GPS Control Program, that let you use internal Lucent/HP command line inputs.

Then we’ve tested the phase noise from the 10 Mhz output :


20141220_182748And the 15 Mhz output :



Finally , we’ve tried to connect pin 5 from the 1PPS exit (J6) to the CTS pin of the RS-232 to see any other difference in correction and synchronization between the two units:(the first one should receive 1PPS just from the diagnostic port instead)Meanwhile I’ve added live data/minute with GPSCon software under Debian 7 and Wine so  now it’s possible to see live data from  Lucent:

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