Three things the tracker was leaving to chance on a FlexRadio, all reported from
a real pass.
ANTENNAS. Settings ▸ FlexRadio holds a per-band RX/TX antenna map, and it was
applied in exactly one place: the entry form, on a band change, to the active
slice. A pass never goes through that path — the tracker arms two slices itself.
So both were left on whatever the radio last used, and a station with
transverters (XVTA on 2 m, XVTB on 70 cm) heard nothing at all, having
configured precisely the thing being ignored. The two slices are on two
different bands, so they cannot share one setting: the downlink takes the
receive antenna for ITS band, the uplink the transmit antenna for its. Per
slice, not through sendSlice, which addresses whichever slice is active — during
a pass that is the downlink, so the uplink would never have been set.
SIDEBAND. satMode forced USB above 30 MHz on both sides. An inverting
transponder turns the passband over, so lower sideband up comes back as upper
sideband down: FO-29, RS-44 and AO-73 were being worked with the operator's own
audio going through upside down. The tracker now decides both sidebands from the
transponder's inverting flag and passes them separately; a bare "SSB" still
means USB, so nothing else changes.
CTCSS. Nothing set it, on any bird. The frequency plan has carried the tone all
along — 67.0 on SO-50 and AO-91, 141.3 on PO-101 — and an FM repeater does not
answer without it, which is indistinguishable from a satellite that is not
there. It goes on the uplink slice, value before mode so the radio cannot
transmit the previous tone in the gap between two commands.
Written against the SmartSDR slice API and UNTESTED on hardware.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Reported as "the Doppler moves the frequency enormously", and it did: a 2 m
downlink was being shifted two megahertz across a pass instead of three
kilohertz, in the wrong direction.
The propagator library reports a range rate that is not one. Measured against
the range it is meant to be the derivative of, on this station's own cached
elements:
PO-101 library -1457.3 km/s measured +6.227 km/s
ISS library +2036.8 km/s measured -5.522 km/s
Wrong by a factor of some 250 and of the wrong sign, so the correction both
overshot and pushed the operator away from the station they could hear. Nothing
else was affected — the elevation and the passes come from the look angle, which
is right — which is why this survived: the satellite was in the correct place on
the map while the radio was told to go megahertz away from it.
So OpsLog computes it itself, as the difference between two ranges a second
apart. That cannot be wrong in either magnitude or sign: it differentiates the
very number the panel displays. Two extra propagations per call, which is
microseconds.
Two tests pin it, and both fail against the old behaviour: a range rate faster
than orbital velocity is a units mistake, and the Doppler on the two bands
satellites are worked on has a textbook size — about ±3.5 kHz on 2 m, ±10 kHz on
70 cm.
cmd/satdiag is the throwaway that found it, kept because the next report of this
shape ("the frequency moves oddly", "that pass is not real") is answered by the
same three numbers: which elements the satellite resolved to, the range rate
reported against the range rate measured, and the Doppler each transponder gets.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
rouggyandClaude Opus 5