Decoding Flex 1600 Pager Traffic with RTL-SDR Video Tutorial

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Rein Smit


This is a report about using a RTL dongle in combination with a PLL LNB to receive a beacon
signal off the moon. Moon signal sent to the moon by a Moonbounce group in Germany.
( Amateur Radio )

Thanks in advance in case you post it.

Regards Rein Smit

Most of us probably know about the 10 GHz beacon being operated by the DL0SHF group since
some time ( QRG = 10.368.025 MHz )

DL0SHF transmit a signal to the moon when the moon is visible at the site. The run 2 modes
50 and 500 W output, 20 seconds on, 40 seconds off.

Last night, I managed to detect the beacon with a very simple receiving package. Amazing enough,
using WSJT moon tracking data, the signal appeared right away when the moon appeared here above
the trees.

The signal lasts only 20 seconds but then 40 seconds later, it returned! By the books.

I use a simple 10 GHz receiver here that I use for scouting signals on 10 GHz terrestrial as member
of the San Bernardino Microwave Society.

It consists of a RTL Dongle IF block tuned to 618 MHz as IF.
Front-end is a PLL LNB, not modified, running with 9.750 GHz LO

The LNB is powered with 12 Volts by means of a Bias Tee.

Both items can be acquired for about USD 25.- on eBay and other places.

The antenna is a standard 18 inch satellite off-set dish.

The antenna has some elevation control and the feed ( LNB ) can be rotated for polarity control.

Every variable is manually operated.

At times I measured the beacon as high as 15 dB above the noise using HDSDR as DSP processor software.

The beacon was running in the 500 W output mode during these observations.

Here are some pictures: , signal visible in filter window as a smear, and in wide band window at about

618.010 MHz as a short line lasting ab0ut 20 seconds ( top waterfall )

Some pictures of the set-up and receiver.

Thanks Per, DK7IJ and the DL0SHF Group.

73 Rein W6SZ