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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