> I do not recognize the GPS receiver module, but it has the following > number on it: TNL 22880-B. I have the schematics for the overall > DATUM 9390-25054, but the GPS module is just a block. By the way, > the GPS block on the DATUM overall schematic is marked, "SV6 / > (TANS)". I suspect this means something noteworthy. "TNL" is Trimble Navigation Labs (their original name). "TANS" is Trimble Advanced Navigation Sensor, a GPS receiver designed circa 1989 for UAVs and similar mil/aero applications. Almost certainly has six GPS channels. Generally spoke a version of TSIP, like the Thunderbolts. Often RS-422. "SV6" as someone else mentioned, is another Trimble 6-channel receiver from the same era. I think it was more commercial than military. Probably also spoke TSIP. 22880 is the Trimble part number for the board you have, rev B. Trimble used random 5-digit part numbers until very recently, when they had to go to six digits because they'd used up all the 5-digit numbers. That only took about 25 years. :) You might be able to hook up Lady Heather to snoop the receiver communications on one of your good Datum units. If that works, you might be able to hot-wire a Thunderbolt in place of your dead 22880 board (assuming it really is dead). Cheers! --Stu