25 satellites, typed by hand and never revisited. Eight of them were the
first-generation Tevel constellation, which re-entered in 2024; four more had
come down too; and the nine Tevel-2 satellites that replaced them, the Chinese
space station, AO-27, AO-123 and twenty others were simply absent. So: 44
satellites now, and a generator instead of a memory.
cmd/satgen joins three public sources on the NORAD catalog number — Celestrak's
amateur group and PE0SAT's mirror for which birds OpsLog can actually get
elements for, and SatNOGS DB for the transmitters. It is a one-shot tool, run by
hand, the same arrangement as cmd/cntygen, and it is deliberately conservative:
- It never destroys a curated entry. The hand-written plans hold things
SatNOGS does not reliably carry — a CTCSS tone, the QO-100 passband as
operators describe it — so an existing bird keeps its data and only gains
its catalog number.
- It prunes on the re-entry date, which is a fact SatNOGS publishes rather
than a judgement about which of the missing satellites are missing for good.
- It refuses a digital uplink that does not say what it is. A GMSK uplink is a
command channel far more often than a digipeater, and shipping the wrong one
invites somebody to transmit on a control frequency. An analog uplink with
both ends is a contact by construction, which is what catches the repeaters
that describe themselves only as "Mode V/U FM".
- Its output is deterministic. One satellite can hold two catalog entries —
GreenCube is 53106 in one feed and 53109 in the other — and iterating a map
picked a different one each run.
A bird now carries its NORAD number, and that is how its elements are found.
Names were the only join before, and they are written differently by every party
involved: "TIANYAN 01" and "TO-108" are one satellite that had never once met,
so TO-108 tracked nothing at all.
And the plan now reaches a station that has already run OpsLog. The editable
copy was written on the first launch and was the operator's list for ever after,
so a release adding nine satellites reached nobody who had opened the tab. It is
merged on each load instead: a satellite they already have is untouched, edits
and corrections included, and only the ones they have never seen are added.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
The foundation of the satellite branch, and nothing above it yet: where a
satellite is (SGP4 from akhenakh/sgp4, Apache-2.0 and pure Go, so the
no-cgo rule holds), where it will be (passes with an elevation floor,
because a three-degree scrape is a line in a table that will never be a
QSO), and what its motion does to a frequency.
The Doppler pair is the part worth being careful about: the two
corrections go in OPPOSITE directions. The downlink arrives shifted and
we tune to meet it; the uplink must LEAVE shifted the other way to land
on the transponder's nominal input. A test pins the signs and the size —
7 km/s on 2 m is about 3.4 kHz.
Elements keep their raw lines beside the parsed form: that is what the
cache stores and what an operator pastes by hand for a bird no feed
carries yet, which is exactly when everyone wants to hear it.
rouggyandClaude Opus 5