NOAA 15 satellite pass received

NOAA 15 made a pass over my QTH this morning with a maximum elevation of 35 degrees.

Not ideal but I was surprised to start receiving the satellite’s signal on the very minute of its rise above the horizon. At this point, it was being received¬†2.5 kHz above the onboard transmit freq of 137.620 MHz due to Doppler. Total shift during the pass was 5.7 kHz.

The receiver was a FunCube Dongle Pro+ using the homebrew QFH antenna that I mounted to my chimney yesterday. Software was SDR#. Compensating for Doppler was a simple matter of setting SDR#‘s tune steps to 100Hz and then clicking periodically to keep the signal centered in the 40 kHz bandwidth. With a slightly wider BW, I doubt any compensation would be needed at all. SDR# allows the recording of both an audio file and the I/Q data – all I needed here was an audio file, which was recorded at a 48 kHz sample rate. After the pass I reduced the sample rate to 11025 Hz in Audacity for compatibility with the WXtoIMG software that converted the audio file to the image below.

A map overlay is also provided based on home QTH input during the software’s set-up. I still have a bit to learn about all this but am happy with initial results of such a small receiver, a $6 antenna and a lower-than-ideal pass. One thing I need to find out is whether or not I can configure the WXtoIMG software to accept the audio directly from the FCD+ during a pass and then spit out an image afterward without me having to manually go through the Audacity detour.

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Screenshot of SDR# during reception

Screenshot of SDR# during reception

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Resulting image showing southeastern US and Caribbean. I’m at the yellow +

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Official image from NOAA

Official image from NOAA of same area at same time.

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  4 comments for “NOAA 15 satellite pass received

  1. August 25, 2013 at 8:25 am

    Hi John,

    Yes, sat RX is funny.
    It’s a long time already but I remember receiving NOAA APT was easy with simple homebrew antenna. Transmitted power is rather high (around 10W I think) and the path is clear…
    My last Sat experience was with ArisSat-1 with my kids. The bird was easily copied on a handheld and easy to understand voice beacon. Receiving the telemetry was fairly easy too, SSTV proved to be more tricky.

    BTW, I am launching a new website called QScope.org for log statistics but with a focus on contesting. Have a look at it and please give me your feedback.

    73,
    Yan.

    • August 25, 2013 at 8:49 am

      Yes they do seem quite easy to receive. Here is an image from a pass yesterday that was only 13 degrees high at maximum elevation. I’m curious to see how low of a pass I can receive and still get a decent image.

      This is the Pacific area just west of Baja California:

      • August 25, 2013 at 10:04 am

        Nice shot. Did you apply the mask yourself or is there any software to automatize this ?
        As usually I am using dipoles or small yagis with manual beaming, my better receiving were near AOS or LOS, because it’s easier to know where is the bird…

        Good noght!
        Yan.

        • August 25, 2013 at 10:47 am

          The map overlay is done automatically by WXtoIMG.

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