MISSION OPERATIONS MANUAL: ISS AMATEUR RADIO CONTACT
DOCUMENT ID: ARISS-OPS-001

This manual provides the essential instructions for contacting the International Space Station (ISS) using amateur radio. Operations are only possible during a valid orbital pass over your ground station. An average contact window will last approximately 10 minutes from Acquisition of Signal (AOS) to Loss of Signal (LOS). Good luck!

1.0 MISSION PREPARATION

Before you can make contact, you need the right gear and knowledge.

1.1 Equipment Checklist

Transmit & Receive: Dual-band VHF/UHF Transceiver
A radio that can transmit (TX) and receive (RX) on 2-meter (VHF) and 70-cm (UHF) bands. One with full-duplex capability is highly recommended.

Receive Only: Software Defined Radio (SDR)
A cost-effective option for receiving ISS signals (SSTV, APRS, Voice). An SDR dongle connects to a computer and uses software like SDR# or GQRX to tune and demodulate signals.

Antenna: Directional Yagi or a good Vertical
A Yagi antenna focuses your signal, increasing success. A rotatable Yagi is best for tracking the ISS. Even a simple outdoor vertical antenna can receive strong signals.

TNC (for packet Tx): Terminal Node Controller
A hardware or software-based modem (like Direwolf) is required to send digital APRS messages through a transceiver. 

1.2 Software & Tools

ISS Tracking
To know exactly when the ISS will be in range of your location.
Recommended Options:
• Web: ISS Pass Predictor or AMSAT
• Android: Heavens Above
• Apple: SatSat

SSTV Decoding
To convert the audio signals from an SSTV transmission into a viewable image.
Recommended Options:
• Desktop: MMSSTV, QSSTV
• Android: Robot36

APRS Software
To send and receive digital APRS messages and see other stations on a map.
Recommended Options:
• Desktop: YAAC (multi-platform) / TNC: Direwolf
• Android: APRSdroid (Android)

2.0 COMMUNICATION ACTIVITIES & MODES

There are several ways you can communicate using the ARISS hardware on the ISS.

2.1 General Voice Contacts (Talking with Astronauts)

Astronauts occasionally make unscheduled voice calls ("CQs") to any amateur radio operator.

  • Downlink (Rx): 145.800 MHz FM
  • Uplink (Tx): 145.200 MHz FM

Doppler Effect: The ISS travels at over 17,500 mph, causing a frequency shift of up to +/- 3.5 kHz on the 2m band. For best results, adjust your receiving frequency.

  • As ISS Approaches: Tune to 145.8035 MHz.
  • When ISS is Overhead: Tune to 145.800 MHz.
  • As ISS Departs: Tune to 145.7965 MHz.
    SDR Users: Set your receiver bandwidth to at least 30 kHz to capture the signal even as it drifts.

2.2 Using the FM Voice Repeater (Talking with Other Hams)

The ISS often operates as a cross-band voice repeater for the ham community.

  • Downlink (Rx): 437.800 MHz FM
  • Uplink (Tx): 145.990 MHz FM (Requires a 67.0 Hz PL tone)

Doppler Effect: The shift is much greater on the 70cm UHF band (up to +/- 10 kHz). You must adjust your receive frequency to maintain a clear signal.

  • As ISS Approaches: Tune up to 437.810 MHz.
  • When ISS is Overhead: Tune to 437.800 MHz.
  • As ISS Departs: Tune down to 437.790 MHz.

2.3 Using the APRS Digipeater (Digital Messaging)

The ISS relays digital APRS packets. This is an excellent mode for both traditional radios and receive-only SDRs.

  • Uplink (Tx) / Downlink (Rx): 145.825 MHz FM (Worldwide).
  • Setup (Transmit): Configure your radio and TNC/software to send packets with the digipeater path set to ARISS.
  • Operation (Receive): Simply tune your receiver or SDR to 145.825 MHz. You can feed the audio into decoding software to see the packets.

2.4 Receiving SSTV Events (Image Downlinks)

ARISS periodically schedules Slow-Scan Television (SSTV) events. This is a receive-only activity, perfect for beginners and SDR users.

  • Downlink (Rx): 145.800 MHz FM
  • SSTV Modes: The most common modes are PD120 and PD180. Your decoding software should be set to "Auto-detect" if possible.
  • Procedure:
    1. Tune your receiver or SDR to 145.800 MHz and account for the Doppler shift as described in section 2.1.
    2. Route the audio output from your radio to your computer or smartphone.
    3. Open your SSTV software (e.g., MMSSTV, QSSTV) to watch the image decode in real-time.

3.0 ADDITIONAL MISSION SUPPORT & INFORMATION

For official announcements, schedules, and technical guides, consult these organizations.