Field Guide · protocol

Also known as: HRIT, GOES-R HRIT

GOES HRIT (High Rate Information Transmission) is the digital image-and-data downlink from NOAA’s geostationary GOES weather satellites, broadcast near 1694.1 MHz in L-band. Unlike the polar 137 MHz systems, a GOES satellite hovers over a fixed point on the equator, so its BPSK downlink is always present and a ground station can use a small fixed dish. The bitstream is heavily protected — a convolutional code with Viterbi decoding on the inside and a Reed–Solomon code on the outside — so the imagery arrives essentially error-free.1

GOES at GEO (~35 786 km), fixed over equator small fixed dish + LNA 1694 MHz BPSKViterbi + Reed–Solomon
GOES HRIT is an always-on 1.7 GHz BPSK downlink from a fixed geostationary satellite, receivable with a small dish and heavily error-corrected.

Overview

The current HRIT service flies on the GOES-R generation (GOES-16 through GOES-19), which became operational from 2017 onward and replaced the older, slower LRIT service. From geostationary orbit a single GOES satellite images an entire hemisphere, and HRIT relays a rebroadcast of that imagery along with the EMWIN text/weather-product stream and the DCS data-collection reports from remote ground sensors.1

Technical characteristics

Property Value
Orbit Geostationary (~35 786 km)
Downlink ~1694.1 MHz L-band
Modulation BPSK
Symbol rate ~927 ksym/s (GOES-R HRIT)
Error correction Inner Viterbi (r=1/2) + outer Reed–Solomon, with interleaving
Framing CCSDS virtual channels
Content Full-disk/ABI imagery, EMWIN, DCS

The concatenated coding is the classic deep-space recipe: the inner Viterbi decoder cleans up most random bit errors, and the outer Reed–Solomon block code mops up the residual bursts, so even a marginal dish delivers a clean picture.2

History

GOES has carried a low-rate image rebroadcast for decades (WEFAX, then LRIT); the GOES-R series upgraded it to the faster, higher-resolution HRIT service and modern CCSDS framing. Together with the polar Meteor-M LRPT and the legacy analog NOAA APT, it rounds out the set of directly receivable civilian weather-satellite downlinks.

Deployment

HRIT is a receive-only broadcast. Because the satellite is fixed in the sky, a modest prime-focus parabolic dish (or a specialised grid/loop feed) with a 1.7 GHz low-noise amplifier and an SDR can lock the signal continuously, and open-source software handles the BPSK demod, Viterbi/Reed–Solomon decode, and image assembly.

Decoding it with GopherTrunk

GopherTrunk does not decode GOES HRIT. It is a VHF/UHF land-mobile trunking scanner, while HRIT is an L-band satellite imagery protocol with CCSDS framing and a Viterbi/Reed–Solomon chain unrelated to the land-mobile voice systems GopherTrunk targets. It is listed here as the geostationary counterpart to Meteor-M LRPT and NOAA APT, and as a well-known SDR weather-satellite project.

Sources

  1. GOES-R series — Wikipedia, for the GOES-R satellites and the HRIT downlink, EMWIN, and DCS services. ↩ ↩2

  2. Reed–Solomon error correction — Wikipedia, for the outer block code used in the concatenated HRIT coding scheme. ↩

See also