NOAA ITOS High Resolution Picture Transmission (HRPT)
The NOAA ITOS (Improved TIROS Observation Satellite) series of satellites transmit high resolution pictures from the VHRR (main radiometer) and calibration/telemetry data over an analog HRPT link. Additionally, the same signal is used to transmit stored data.
The signal is an analog video signal, FMFrequency Modulation modulated, encoded over an FMFrequency Modulation link. The main payload of HRPT is VHRR data composed of two channels in the visible, and infrared spectrum; additionally, telemetry similar to APT is included in the image, and the data are transmitted at 360 lines per minute (LPM).
This signal is not to be confused with the more modern, digital HRPT signal used by the ATN (POES) series of satellites, or with the variant used by Russian METEOR-M satellites.
- 2 channels from VHRR radiometer: an infrared and a visible one.
- Calibration data for VHRR channels
- Spacecraft telemetry and monitoring (TLM)
- Right-hand circular polarization
- FMFrequency Modulation modulation encoding an FMFrequency Modulation analog video signal
- 1 MHzMegaHertz (MHz) 10^6 Hz bandwidth
- Transmit power 5 watts
Satellites transmitting HRPT
All ITOS satellites are officially decommissioned. However, recently NOAA-2 (ITOS-D) launched over 50 years ago, started transmitting again a signal, that matches the original specifications. No imagery is transmitted, but the telemetry lines are visible.
The signal is on for 30 seconds and off for about a minute while the satellite is passing, no signal is transmitted at night.
Last known working reception and decode, was on January 11th, 2023 in Genoa, Italy.
|NOAA 2 (ITOS-D)||1697.5 MHzMegaHertz (MHz) 10^6 Hz||Only while not eclipsed; no imagery transmitted, only telemetry.|
- File:Noaa 31338.pdf
- Article by Derek OK9SGC about the satellite
- GNU Radio decoder file (see the tutorial above)