Tutorial GOES HRIT

Tutorial: GOES HRIT

What it is. GOES-16, 18 and 19 are geostationary weather satellites that hover over the Americas. They broadcast full-disk, CONUS and regional pictures plus text products (EMWIN) on 1694.1 MHz as HRIT and LRIT. Because the satellite does not move, you aim a dish once and receive pictures all day. The signal is weak, so a dish with a low-noise amplifier is needed.

What you need

• Radio. A radio that tunes 1.69 GHz and runs at 2.4 Msps (the mode asks for 2.4 Msps; the lowest rate that works is 2 Msps). A HackRF, Airspy, SDRplay, PlutoSDR or similar; check Supported-radios. Check the radio's page for its tuning limit at 1.7 GHz.
• Antenna. A dish of about 1 m, or a grid antenna, aimed at the satellite, with a low-noise amplifier and a 1.7 GHz band-pass filter at the feed ("the signal is far below the noise of a plain antenna"). Keep the cable short. Antenna power through the radio's bias-tee or an injector powers the LNA.
• Frequencies. GOES-R HRIT / EMWIN 1694.100 MHz (the mode default), and EMWIN at 1692.700 MHz in the frequency database. Tuning range 1670 to 1710 MHz.

Before you start

• Pointing: the satellite's azimuth and elevation depend on your location. Use a satellite finder tool; GOES-East is at 75W and GOES-West near 137W. Fix the dish firmly; a few degrees of error matters.
• Gain: moderate; strong terrestrial signals near 1.7 GHz (cellular, radar) cause overload, which the filter removes.
• Polarity: circular feed is common; check the feed documentation.

Step by step

1. Mode list, group Satellite & navigation, entry Weather images, 1694 MHz.
2. Check frequency 1694.1 MHz and 2.4 Msps.
3. Press Start. The prompt reads "Start the receiver. GOES HRIT needs a dish..."
4. Slowly adjust the dish while watching the signal quality until frames lock. State shows progress.
5. After lock, the product list fills.

What you should see

A BPSK carrier of about 927 ksym/s; the Products list grows with images and text. Pictures arrive line by line, so a large full-disk picture takes a while; the Done column shows the progress. EMWIN text products and ZIP files are unpacked.

Reading the screen

• Products. Columns Product, Kind (full disk, mesoscale, CONUS, relayed image, EMWIN text, admin message) and Done (percentage and size). A filter narrows the list. Newest shows the most recent image as it arrives (choosing a product in the list turns this off).
• Image viewer. The picture grows as lines arrive; a picture that cannot be decoded here is saved as it came.
• Save saves the shown product into the goes folder (images as PNG, pictures and ZIP files as they came, text as .txt). Save automatically writes every product once complete. Clear empties the list.
• Log and State.

Options and settings

Filter by product kind; Newest; Save; Save automatically.

Troubleshooting

• No lock. Dish misaimed or LNA unpowered; peak the signal slowly.
• Frames with errors. Marginal signal; improve the feed or add gain.
• Overload. A 1.7 GHz filter helps.
• Incomplete pictures. Lost lines; they are saved as they came.
• Wrong satellite. GOES-West or East depends on your location; not every satellite is visible everywhere.

Tips

Run a full day to collect all products. A small grid antenna with a good LNA is enough in the Americas.

Legal and privacy notes

HRIT/LRIT and EMWIN are open public broadcasts of NOAA, intended for reception. Receiving is legal. See Legal.

Under the hood

BPSK 927 ksym/s, K = 7 Viterbi, Reed-Solomon (255,223) x 4, CCSDS VCDU / M_PDU / CP_PDU, LRIT/HRIT files with Rice compression (CCSDS 121) and JPEG images.

Related

Mode-GOES-HRIT, Tutorial-Elektro-L, Tutorial-HRPT-AHRPT, Tutorial-Meteor-M-LRPT, Tutorial-Weather-satellite-images, Troubleshooting