I am having a problem getting computer-controlled antenna tracking working in time for Field Day next weekend! System is G5400B az/el rotors, ST-2 trackbox, and SatPC32. Software is communicating with ST2 and rotors. The ST-2 appears to be properly configured, including the 180 deg elevation rotor range and the location of the azimuth stops at 180 deg (South). Manual control of the rotors is normal using the G5400 controller, ST-2 panel buttons, serial port commands to ST-2, and using the SatPC32 manual interfaces.

SatPC32 sometimes goes into "flip mode" (use max elevation rotor range of 180 deg to avoid loss of tracking from a 180 deg azimuth swing mid-pass for high elevation passes) immediately at AOS. According to the manual, SatPC32 will not begin tracking a pass in flip mode. I've seen several times now SatPC32 enter flip mode immediately at AOS for low and mid-elevation passes where flip is not needed for the 2nd half of the pass. Toggling automated rotor control (R+/-) off and on during the early part of the pass doesn't alter the behavior.

I assume I have an incorrect value in the SatPC32 rotor setup (yes, I've closed and restarted the program). Guess - how does the rotor setup use the "N" or "S" field to locate the azimuth rotor stops (my rotor has the stops at 180 deg/South) and does this come into play for flip mode? This doesn't explain why a flip would be commanded at AOS. I could prevent flip mode by setting the max rotor elevation to 90 deg, but I'd like to have flip mode capability when I need it. Suggestions? Can someone email me (no need to clutter the list) working settings for either ST-2 or LVB Tracker (I think they are electronically the same)?

I've tried searching the amsat-bb list archive (to the extent it is searchable - if someone has a way to use, say, Google and the "site:" command or similar to do this, let me know) and searched the SatPC32 site and files and haven't found a clear answer.

It just occurred to me that I can use direct serial port commands to the ST2 to test that the azimuth rotor moves CCW from, say, 175 deg to 185 deg, and does not try to go CW through the rotor stops. Repeating with SatPC32 interface should verify I have the azimuth stops set correctly without having to wait for a suitable satellite pass. I am hoping this may have something to do with flip mode being triggered. Or it may just give me something to try between satellite passes until I figure it!

Thanks & 73 Steve KS1G ks1g@amsat.orgmailto:ks1g@amsat.org