Mode HRPT AHRPT

HRPT / AHRPT: MetOp AVHRR pictures at 1.7 GHz (needs a dish and a fast radio).

Group	Weather & science
Default frequency	1701.3 MHz
Default sample rate	6 Msps
In the mode list	Weather pictures, 1.7 GHz

Step-by-step: Tutorial-HRPT-AHRPT

What HRPT / AHRPT is

HRPT and AHRPT are the high-resolution direct broadcast of polar weather satellites (MetOp, FY-3, formerly NOAA), carrying the full AVHRR image data.

Frequencies and settings

MetOp-B / -C AHRPT on 1701.3 MHz (QPSK 2.33 Msym/s, K = 7 Viterbi, Reed-Solomon (255,223) x 4, CCSDS packets, AVHRR lines), FY-3 AHRPT (QPSK, frames counted only), retired NOAA HRPT (BPSK, Manchester, 665.4 kbit/s).

Setting	Value
Start frequency	1701.3 MHz
Tuning range of the mode table	1690 to 1710 MHz
Sample rate asked	6 Msps
Lowest working rate	4 Msps
Channel width	4.5 MHz

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is Weather pictures, 1.7 GHz.

What OnAir shows

The AVHRR picture grows line by line (colour or one of five channels), saved as PNG. Needs a dish (about 1 m or more, following the satellite) with an LNA at the feed and a fast radio (4 Msps or more; not an RTL-SDR). NOAA-15, 18 and 19 are retired.

Tips and caveats

• Checked with generated signals and impairments; recordings of real signals welcome.
• Which radio: No: this mode needs a radio that samples at 4 Msps or more, and an RTL-SDR reaches about 2.4 Msps.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: Receiving these signals is legal in most countries. OnAir is a receiver. See Legal.

Related pages

• Weather satellite images
• All modes, Weather & science
• Supported radios, Troubleshooting, FAQ
• More in Weather & science: NOAA Weather Radio SAME, Radiosonde, Time signals, Ionospheric sounders, Radio astronomy