Below are notes on how to copy NOAA weather images -- directly from weather satellites!

NOAA Polar Weather Satellite Tips

Prepared by Frank (N1UW) January 11, 2020

Satellites and Frequencies

These satellites have active APT (Automatic Picture Taking) working:

• NOAA-15 137.62 MHz

• NOAA-18 137.9125 MHz

• NOAA-19 137.1 MHz

Notes: At AOS, Doppler shift is about 2.8KHz high and at LOS it is about 2.8KHz it is low.

SDR# Settings

Besides the usual defaults, make these changes:

• Make sure the receiver gain setting is about 40 dB.

• Set the mode to NBFM

• Set the bandwidth to 32 KHz (maximum).

Notes: Use the up/down buttons to change the bandwidth or use the keyboard to enter “32” to the left of the decimal point. If you just type in a value and press “Return”, the bandwidth sets to zero and you must then use the up button to increase the bandwidth to greater than 1.0 before you can re-enter a value with the keyboard. I think this is a software glitch.

• Set the frequency step value to 100 Hz.

• Set the RECORD bit level to “8-bit”.

• Check the “AUDIO” box and uncheck the “BASEBAND” box.

Notes: The WAV file will be written into the folder where the SDR# executable lies.

NOAA-APT Image Decoder Software

• Go to https://noaa-apt.mbernardi.com.ar and download Windows x86_64 zip.

• Unzip and install the software.

Notes: There is more advanced software available but I haven’t had the opportunity to try them. This software is easy to use and is a good first step.

Capture Procedure

• Set your starting frequency 2.8KHz high.

• Don’t forget to start recording audio at AOS.

• Start out with your antenna vertically polarized. That seems to work best for me. Twist it to optimize signal strength.

• Watch the frequency and track it as the satellite passes overhead. Doppler shift is very slow near AOS and LOS but very rapid when near zenith.

• After you end the recording, start the NOAA-APT software, choose the WAV file for input and type in “BMP” for output.

• Click on START and enjoy