Ground Stations, TLE Tracking, Doppler & SatNOGS

G/T from first principles: what makes a good amateur ground station

For a weak downlink such as that of a PocketQube, the ground station contributes a single number to the link budget: its figure of merit G/T. We build the system noise temperature of five amateur receive chains with the Friis cascade. A 13 dBi crossed Yagi with a low-noise amplifier at the mast reaches about 200 K and −10.0 dB/K; moving the same amplifier indoors behind 1.8 dB of cable raises the noise to 366 K, and leaving it out to about 1600 K. Applied to Grizu-263A’s 20 dBm, 4800 Bd downlink, the three chains decode above 5°, 13° and 42° elevation, which at 41.45° N means about 32, 16 and 2 minutes of usable contact a day. Omnidirectional antennas never close at 4800 Bd. We end with a checklist for building and measuring a station.

Tracking a 5 cm satellite

A bare 50 mm cube sits deep in the Rayleigh scattering regime for UHF space-surveillance radars, yielding a radar cross-section near −43 dBsm. Once its 437 MHz tape-spring monopole or dipole deploys, resonant wire scattering boosts RCS by 25–30 dB. We examine radar cross-section across UHF, S-band and X-band and explain how Differential Doppler resolves rideshare TLE lotteries.

Pass geometry and Doppler for small-satellite ground stations

Everything a ground station does with a low Earth orbit satellite is set by a few lines of geometry. For a 525 km Sun-synchronous orbit, a pass lasts at most 11.9 minutes above the horizon and 7.7 minutes above 10°, and the range shrinks from 2641 to 525 km, a 14 dB swing in path loss. At 437.19 MHz the Doppler shift sweeps from +10.2 to −10.2 kHz, fastest at closest approach, where it changes by up to 148 Hz per second. A station at 41.45° N sees 3.3 passes a day above 10°, about 20 minutes in total, with gaps of up to 13 hours; one at Svalbard sees 11. We derive these numbers, show how a Doppler curve measures the orbit, and close with rules for tracking PocketQubes and CubeSats.

PocketQube picosatellites: A review of standards, mission trends and miniaturization constraints, with lessons learned from Grizu-263A, Türkiye’s first PocketQube

IARU/ITU Spectrum Coordination, Deployers & Operations

AlbaPod and CubeSat deployer integration, ≥30-minute deployables / ≥45-minute RF inhibit timers (CDS Rev. 14.1 §2.4.4–2.4.5), IARU/ITU API filings, NORAD TLE lottery identification, and SatNOGS ground networks.