Ham Satellite Tracking

Working amateur satellites — small spacecraft like AO-91 / AO-92, ARISS (the ISS ham repeater), the IO-117 / Greencube digipeater, FUNcube — is a contained, satisfying corner of ham radio. Pass prediction + Doppler correction + rotator control is the software stack; this page covers it. For weather satellites see Weather Satellites & APT; for SDR Receivers hardware.

Pass prediction & rotator control

• ★ Gpredict — Csaba OE7CSA / OZ9AEC; cross-platform (Linux / Mac / Windows); the FOSS gold standard. Real-time visualization, pass prediction, Hamlib rigctld integration for Doppler-shift radio control, rotctld for antenna rotators, footprint maps, multi-satellite tracking. GPLv2.
  • https://github.com/csete/gpredict
• SatPC32 — Erich DK1TB; Windows; closed; paid (~$45 with lifetime updates). The Windows ham-sat standard; deeper rotator integration for Yaesu G-5500 / Hy-Gain than Gpredict on Windows.
• PstRotator — Windows; closed; paid (~$45); rotator-only, integrates with Gpredict / SatPC32 / SDR# / WSJT-X.
• HamLab (cross-platform) — newer commercial sat tracker; closed paid.
• Look4Sat (Android) — cross-platform sat tracker app; FOSS GPL. Phone-as-portable-pass-predictor.

Web / phone schedulers

• ★ Hams.at — N6UA; the modern web sat-pass scheduler. Pre-coordinate passes with other ops; live activity heat map; mobile-friendly; integrates with AMSAT-NA. Free.
  • https://hams.at
• AMSAT-NA Pass Predictor — classic web tool; free.
• Heavens-Above — visual passes (mostly for ISS / SatNOGS); free.
• N2YO — sat database + passes; free.

SatNOGS — open ground-station network

• ★ SatNOGS — Libre Space Foundation. A network of >800 amateur ground stations worldwide that schedule and decode satellite passes for everyone — including academic cubesat teams. Hardware blueprints, Pi-based ground-station software, network coordination server. AGPL.
  • https://satnogs.org
• SatNOGS Network — the scheduling / observation aggregator.
• SatNOGS DB — the canonical TLE / transmitter / mode database; everyone's tracker pulls from this.
• SatNOGS Client — Python; runs on a Pi 4/5; controls SDR + rotator + decoder pipeline.
• SatNOGS Optical — newer 2025 extension for optical (camera-based) satellite tracking.

Decoders for amateur sats

• gr-satellites — Daniel Estévez EA4GPZ; decodes hundreds of cubesats and amateur sats out of GNU Radio. The reference software. GPL.
  • https://github.com/daniestevez/gr-satellites
• gpredict + WSJT-X / Fldigi / SDR# audio chain — for FM voice / linear-transponder sats; Gpredict drives the radio Doppler, audio goes into the digital-mode decoder.
• AO-91 / FM birds — just an FM audio receiver, no decoder needed.
• GreenCube / IO-117 — APRS-style digipeater on a sat; Direwolf decodes the AX.25 packets directly. See APRS & Packet.
• FUNcube Dashboard — closed Windows app; decodes FUNcube-1 / Nayif-1 / JY1Sat telemetry.

Hardware

• Yaesu G-5500 azimuth/elevation rotator — the canonical ham-sat rotator; ~$700 new, popular used. Pairs with a GS-232 controller (older) or a Green Heron / EA4TX / Yaesu DXA controller. Integrates via Hamlib rotctld.
• EA4TX ARS / RemoteRig — alternative rotator controllers.
• Yaesu FT-857D / FT-991A / IC-9700 / IC-7100 / Kenwood TS-2000 — common rigs for FM sat work; IC-9700 is the modern single-box choice (full-duplex 144/430/1200 MHz).
• Arrow II antenna (handheld 2 m / 70 cm Yagi) — the de-facto portable / no-rotator antenna for FM sats. ~$150. Lifestyle: walk outside, point at the sky, work the world.
• M2 Antenna 2MCP14 / 436CP30 — fixed crossed-Yagis for serious sat stations.
• Helix antennas — for L-band (1.2 GHz) and S-band uplink/downlink.

Practical guidance

• TLEs (Two-Line Elements). Every sat tracker needs current TLEs. Gpredict / SatNOGS auto-fetch from CelesTrak / Space-Track. Refresh weekly — older than ~2 weeks and predictions drift seconds.
• Doppler correction. A 2 m / 70 cm sat's downlink shifts ±10 kHz across a pass; without auto-Doppler you're chasing the signal. Gpredict + Hamlib + a CAT-controlled radio handles this.
• Full-duplex matters for linear transponders. SO-50 / FO-29 / RS-44 — you need to hear yourself; that's why the IC-9700 is so loved (true full-duplex on different bands).
• FM birds (AO-91, AO-92 RIP, ARISS digipeater, AO-27 RIP, SO-50) — half-duplex is fine. An HT + Arrow II is enough; see "Operate from a park" videos.
• ARISS contacts. When astronauts are on the ISS, occasional voice contacts happen — listen on 145.800 MHz FM.
• Your roof line matters. Below ~10° elevation, signals are mostly noise; the typical "useful pass" is from 10° to 70° to 10° again, lasting 10–12 minutes.
• SatNOGS as a hobby or a mission. Run a station and you'll be auto-recording cubesats from universities worldwide. The data goes into a public archive that academics use; your name is on it.

License / pricing notes

• Gpredict / Look4Sat / gr-satellites / SatNOGS / Hams.at — FOSS / free.
• SatPC32 / PstRotator / HamLab — paid, closed.
• FUNcube Dashboard — closed, free.
• AMSAT membership ($45/yr) — supports the satellite-building organizations; your callbook update fee.

Pick this if…

• Default sat tracker, FOSS: Gpredict.
• Default Windows sat tracker: SatPC32 (paid) or Gpredict (free).
• Phone-as-pass-predictor: Look4Sat (Android) or Hams.at on mobile web.
• Coordinate sat passes with friends: Hams.at.
• Run a Pi-based ground station for the world: SatNOGS.
• Cubesat decoder for any bird: gr-satellites.
• Cheapest path: portable FM birds: Arrow II + an HT (Yaesu FT-65, Kenwood TH-D74).
• One-box-does-everything: Icom IC-9700 + Gpredict + Yaesu G-5500.