Satellites

Satellites

OpsLog predicts passes, points an az/el mast at them, and corrects both sides of the link for Doppler while you work the bird.

Two places share the work:

• Settings ▸ Satellite — where the antenna is, and the machine that points it.
• the Satellites tab — the satellites you follow, the frequency plans, the pass list, and tracking itself.

Where the antenna is

Passes are predicted from your station locator (Station information). Two things are set here on top of it:

• Altitude — the antenna above sea level. It moves the horizon, and so moves the start and the end of a low pass.
• Lowest pass — hides the passes that only scrape the horizon and will never become a QSO.

If your satellite station is somewhere other than the locator your QSOs are logged with, fill in the other site fields. Leaving them empty means "the same place as the rest of the station".

Pointing the mast

The satellite page does not configure a rotator. Every interface is described once in Settings ▸ Rotator (Maps and Antennas), and this page only says which of them follows the satellite.

That is normally a different machine from your HF rotator, and having both is perfectly ordinary — the az/el mast follows the pass while the beam stays where it was.

• Start above leaves the mast alone until the satellite is worth pointing at.
• Move by is the smallest change worth a command. Keep it inside your beamwidth, or the rotator runs constantly for nothing.
• The rotator's own range (360° or 450°) belongs to the interface, in Settings ▸ Rotator.

With no elevation motor

Azimuth only is for a station with an ordinary azimuth rotator and no elevation motor. It works better than it sounds: a pass at the edge of the footprint stays between the horizon and about 15° for its whole length, and a beam's beamwidth covers that, so the bearing alone is enough.

What you give up is the high passes, where a satellite overhead has a bearing that means nothing. With this option on, any rotator can be chosen.

If none of your rotators has an elevation axis, OpsLog says so and points you at the az/el interfaces: ERC-M, EasyComm, SPID Rot2Prog, or PstRotator with elevation ticked.

Through PstRotator

PstRotator handles azimuth and elevation and already knows your controller, so OpsLog sends it the bearing and lets it turn the mast. Its UDP port is in PstRotator under Setup ▸ TCP/UDP Server — 12000 by default.

Nothing else on the page applies in that case: the rotator's travel and its overlap are PstRotator's business.

Orbital elements (TLEs)

Elements come from Celestrak's amateur list, with a mirror behind it, and are kept on disk. So the Satellites tab is full the moment it opens even with no internet — a set a few days old still predicts tonight's passes perfectly well.

For a satellite no feed carries yet, paste its elements. Those are kept in their own file and survive every refresh.

Follow narrows the tab and the pass list to the satellites you choose. Follow none and every satellite that has both elements and a frequency plan is shown.

Tracking and Doppler

Track puts the radio on the satellite and keeps it there: the downlink and the uplink corrected for Doppler, once a second. Tune the receiver freely — the transmitter follows wherever you land.

Uplink trim is your own correction to the uplink, taken from the transmit VFO and kept per transponder. Transponders do not translate by exactly the published difference, and this is where that difference is remembered.

The QSO is logged on the nominal frequency, not the Doppler-shifted one.