High-resolution picture transmission explained

Weather satellite pictures are often broadcast as high-resolution picture transmissions (HRPTs), color high-resolution picture transmissions (CHRPTs) for Chinese weather satellite transmissions, or advanced high-resolution picture transmissions (AHRPTs) for EUMETSAT weather satellite transmissions. HRPT transmissions are available around the world and are available from both polar and geostationary weather satellites. The polar satellites rotate in orbits that allow each location on Earth to be covered by the weather satellite twice per day while the geostationary satellites remain in one location at the equator taking weather images of the Earth from that location over the equator. The sensor on weather satellites that picks up the data transmitted in HRPT is referred to as an Advanced Very High Resolution Radiometer (AVHRR).^[1]

Broadcast signal
The working frequency band for HRPT is L Band at 1.670–1.710 GHz and the modulation types are BPSK and QPSK.^[2] On NOAA KLM satellites the transmission power is 6.35 Watts, or 38.03 dBm.^[3] The METOP-A satellite broadcasts with a bandwidth of 4.5 MHz.^[4]

Reception

Hardware

In order to receive HRPT transmissions a high gain antenna is required, such as a small satellite dish, a helical antenna, or a crossed yagi. Basic reception equipment includes a parabolic dish antenna attached to an Azimuth-Elevation unit. The HRPT signal is further enhanced with a 1.7 GHz pre-amplifier. An HRPT receiver unit and a dish tracking controller are required to steer the Azimuth-Elevation unit controlling the parabolic dish. As an alternative to receiving direct broadcast from polar orbiting satellites, users in Europe and Africa can also receive rebroadcast data from the EUMETSAT EUMETCAST service via Digital Video Broadcasting using a simple stationary satellite dish.^[5]

Software

Both commercial and free software for demodulating HRPT transmission signals exists: Example of commercial demodulation software is XHRPT Decoder.^[6] Free software exists as a part of GNURadio package, the GR-NOAA blocks and flowcharts distributed by Manuel Bülo.^[7]

Free software for decoding data packets contained in HRPT is available, for example DWDSAT HRPT Viewer V1.1.0^[8] or AAPP^[9] with Satpy.^[10]

Satellite status

Organization	Satellite Name	Orbit	Service	Frequency	Data rate	Status
NOAA	NOAA-15	Polar	HRPT	1702.5 MHz	0.665Mbps^[11]	Transmitting
NOAA	NOAA-18	Polar	HRPT	1707.0 MHz	0.665Mbps	Transmitting
NOAA	NOAA-19	Polar	HRPT	1698.0 MHz^[12]	0.665Mbps	Transmitting
EUMETSAT	Metop-A^[13]	Polar	AHRPT	1701.3 MHz	4.66Mbps^[14]	Offline
EUMETSAT	Metop-B	Polar	AHRPT	1701.3 MHz	4.66Mbps	Transmitting
EUMETSAT	Metop-C	Polar	AHRPT	1701.3 MHz	4.66Mbps	Transmitting
CMA	Fengyun 3A^[15]	Sun-synchronous	AHRPT	1704.5 MHz	4.2Mbps^[16]	Offline
CMA	Fengyun 3B^[17]	Sun-synchronous	AHRPT	1704.5 MHz	4.2Mbps	Offline
CMA	Fengyun 3C^[18]	Sun-synchronous	AHRPT	1701.3 MHz	4.2Mbps	Transmitting
RosHydroMet	Meteor-M N2	Sun-synchronous	AHRPT	1700.0 MHz^[19]	0.665Mbps	Offline
RosHydroMet	Meteor-M N2-2	Sun-synchronous	AHRPT	1700.0 MHz^[20]	0.665Mbps	Transmitting
RosHydroMet	Meteor-M N2-3	Sun-synchronous	AHRPT	1700.0 MHz^[21]	0.665Mbps	Transmitting

Notes and References

1. Web site: NOAASIS - NOAA Satellite Information System for NOAA Meteorological / Weather Satellites . 2009-04-12 . https://web.archive.org/web/20060427201736/http://noaasis.noaa.gov/NOAASIS/ml/avhrr.html . 2006-04-27 . dead .
2. http://www.scanex.ru/en/stations/default.asp?submenu=alice&id=specifications
3. Web site: NOAA KLM USer's GUIDE Section 4.1 . 2009-12-08 . 2010-05-27 . https://web.archive.org/web/20100527194915/http://www.ncdc.noaa.gov/oa/pod-guide/ncdc/docs/klm/html/c4/sec4-1.htm . dead .
4. Web site: Archived copy . 2009-12-08 . dead . https://web.archive.org/web/20081126153454/http://www.eumetsat.int/idcplg?IdcService=GET_FILE&dDocName=pdf_aspi_0674_eps_cgs-us-sp&RevisionSelectionMethod=LatestReleased . 2008-11-26 .
5. Web site: EUMETCAST. 5 May 2020 .
6. Web site: USA-Satcom xHRPT decoder setup. 2020-01-05.
7. Web site: A Simple GnuRadio HRPT Decoder. 2020-01-05.
8. Web site: DWDSAT HRPT Viewer - from SatSignal Software.
9. Web site: ATOVS and AVHRR Pre-processing Package (AAPP).
10. Web site: Satpy.
11. Web site: NOAA table of Polar-orbiting Satellites Equator Crossing Times and Frequencies. 2011-09-01.
12. Web site: Operational Satellite Status Information - NOAA Satellite Information System (NOAASIS); Office of Satellite and Product Operations . 2009-05-14 . https://web.archive.org/web/20130703042119/http://noaasis.noaa.gov/NOAASIS/ml/status.html . 2013-07-03 . dead .
13. http://www.eumetsat.int/idcplg?IdcService=GET_FILE&dDocName=pdf_td18_metop{{dead link|date=November 2017 |bot=InternetArchiveBot |fix-attempted=yes }}
14. EUMETSAT Polar System Core Ground Segment:Metop HRPT/LRPT User Station Design Specification

    REF: EPS-ASPI-DS-0674

    DATE: 05/03/03

    ISSUE: 1.1

15. Web site: WMO OSCAR | Satellite: FY-3A.
16. "– AHRPT on the series of FY-3 satellites is disseminated at 1704.5 MHz with a bandwidth of 6.8 MHz at a data rate of 4.2 Mbps or on Metop at 1701 MHz with a bandwidth of 4.5 MHz at a data rate of 4.66 Mbps ."

    Meteorological Satellite Communications

    David F. McGinnis, NOAA

    Markus Dreis, EUMETSAT

    17 September 2009

17. Web site: WMO OSCAR | Satellite: FY-3B.
18. Web site: WMO OSCAR | Satellite: FY-3C.
19. Web site: WMO Oscar Meteor-M N2-1. 2020-01-05.
20. Web site: WMO Oscar Meteor-M N2-2. 2020-01-05.
21. Web site: WMO Oscar Meteor-M N2-3. 2023-09-10.