On Jan 30, 2007, at 1:22 PM, Robert E. Martinson wrote: > Hope everyone has not stopped experimenting with these nicely made, > reasonably priced, units, but certainly the email regarding them > has fallen > to almost zero these last few weeks.
I posted a few emails with the results of my reverse engineering but didn't get any significant response so I haven't posted any more. Investigation goes on however. > They both power up, but > both indicate "No GPS", and the XO also indicates "Fault", the RB unit > indicates "ON". I have the two J5 connectors interconnected per Jim > Miller's email of 12/30/06 at 3:34pm, and the Ref In/Outs with an > SMA cable. They should come out of "NO GPS" after 15-30 minutes. > Even with the receiver plugged back into the XO unit, > the data on the front panel J5-2 is clearly visible with > HyperTerminal & > also Visual GPS is happy with this data. Be careful not to load the interconnect lines down with probes or external level changers. It is easy to knock one or both units into "FAULT" by aggressively probing signals on the interconnect cable. > Even after many hours the RFTG units continue to indicate "No GPS", > and the > XO unit also shows "Fault". I tried the XO unit by itself (no > connections > to the RB unit) and the XO is still unable to obtain lock. I have been > monitoring the crystal frequency (using a clip lead directly from the > crystal) of the XO unit for 8 hours with an HP 5370B locked to my > HP Z3801A Again, be careful of your probe loads. I found this out the hard way - too many loads (50Z on my 5370, freq counters on the oscillator, inverters on the serial lines etc) will spoil your results. I recommend initially bringing the units up in their original, as-designed configuration in order to establish a baseline. As mentioned earlier, you should get GPS lock in 15-30 minutes. Do you have a good DC voltage on the TNC GPS antenna connector when the receiver is installed in the RFTG? The RFTG has its own DC injection circuitry. > I see commands initially being sent to the GPS receiver (monitoring > its > header pin 9 with an oscilloscope), however by simultaneously > monitoring the > calculated position using VisualGPS, its obvious that the receiver > is not > going into position hold mode. It takes 12 hours or so to transition into position hold mode. I use TAC32 for monitoring the receiver and TAC32's "Receiver ID" screen will show the status messages about the mode changes. Have you been able to capture and decode the motorola binary messages going from the CPU to the receiver during initialization? This would be useful. > Don't we have any helpful Lucent employees in the group? I do not know about any Lucent employees in the group but it is very possible that company policy is not to release documentation to the public - and those that do have access to it might like their jobs more than they like the timenuts. It is also possible that the only docs available are written at a high level and would not be very useful in these pursuits. 73 de JIM N8ECI _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
