METOP Advanced High Resolution Picture Transmission (AHRPT)

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METOP Advanced High Resolution Picture Transmission (AHRPT)
Frequencies 1701.3 MHz,1707 MHz
Frequency Range 1701.3 MHz - 1707 MHz
Mode RAW
Modulation QPSK
Emission Designator
Bandwidth 6 MHz
Location Worldwide
Short Description A high-speed digital link used by METOP weather satellites for direct data dissemination.
I/Q Raw Recording
Audio Sample

The METOP series of satellites transmit high resolution pictures from AVHRR and data from several other instruments over an AHRPT link.

Due to a much larger instrument payload than NOAA POES satellites, a faster method of disseminating data from the satellites had to be devised. BPSKBinary Phase-Shift Keying (1 bit per symbol) was replaced by QPSKQuadrature Phase-Shift Keying (2 bits per symbol) and to ensure correct decoding, forward error correction (FECForward Error Correction) was added too. As a result, the data rate passed from 664.5 kbit/sKilobits per second (kbps) of POES HRPT to 3.5 Mbit/s, over 5 times faster, not including overhead of FECForward Error Correction which brings the total data rate to 4.7 Mbit/s.

Data transmitted[edit]

  • 6 channels from AVHRR radiometer, of which 5 transmitted at the same time (satellite switches between channel 3A and 3B depending on light conditions)
  • Image and data from IASI interferometer
  • Data from ASCAT scatterometer
  • 15 channels from AMSU-A sounder
  • 20 channels from HIRS sounder (Not available on METOP C)
  • 5 channels from MHS
  • Data from GOME
  • Data from ARGOS-A DCS data collection system
  • Data from SEM (Space Environment Monitor)
  • Spacecraft RTC (Real Time Clock)
  • Spacecraft telemetry and monitoring (TLM)
  • Administration messages and satellite status

Data structure[edit]

Data are distributed as a stream containing Channel Access Data Units (CADUs), which require further processing to produce Metop L0 products. The stream holds multiplexed data from all Metop instruments, as well as spacecraft telemetry and administrative messages. In addition to being time ordered, frame synched and randomized, CADU’s also hold Reed-Solomon decoding information and quality information.

Signal characteristics[edit]

  • Right-hand circular polarization
  • QPSKQuadrature Phase-Shift Keying (2 bits per symbol) modulation
  • 6 MHzMegaHertz (MHz) 10^6 Hz bandwidth
  • Data rate 3.5 Mbps (4.666667 Mbps including FECForward Error Correction)
  • Viterbi and Reed-Solomon FECForward Error Correction
  • Transmit power 15 watts
  • 1701.3 MHzMegaHertz (MHz) 10^6 Hz prime transmitter, 1707 MHzMegaHertz (MHz) 10^6 Hz backup transmitter

Satellites transmitting METOP AHRPT[edit]

Satellite Frequency Notes
METOP B 1701.3 MHzMegaHertz (MHz) 10^6 Hz
METOP C 1701.3 MHzMegaHertz (MHz) 10^6 Hz No HIRS

Decoding Software[edit]

Decoding Tutorials[edit]

Additional Links[edit]

Additional Images[edit]