Monthly Archives: October 2013

RTLSDR Coherence first test

The first test to see the coherence of two rtlsdr in realtime consist in do a cross-correlation of the two dongles, the cross-correlation is a measure of similarity of two signals.

To do the test I used baudline and tuned to a local VOR/DME. Here in the first picture can see some coherence of the two dongles using one antenna to every rtlsdr:

RTLSDR baudline cross-correlation with 2 antennas

Here the result if disconnect one antenna:

RTLSDR baudline cross-correlation with 1 antenna disconnected

RTLSDR Coherence setup

After the nice videos that Juha Vierinen has shared, looks that some people is interested in use multiple rtlsdr coherent for radar applications for example. I’m starting my experiments with this setup:

RTLSDR Cohernt setup

My setup consist in two rtlsdr dongles with r820t tunner with the xtal removed, connected to a PTS-160 Synthsesizer tunned at 28.8 MHz and locked to 10 MHz GPS reference.

SDR & RadioAstronomy rack

With coherence using radar mehtods, you can get cool images like:

Say Hi to Juno

Recently a nice activity for the Ham radio community was organizated from the JPL. The idea is that the spacecraft instruments can detect a message transmited by the Ham radio operators, here all the info. Waiting the definitive plot from the JPL here my the plot that I was record using a Rfspace SDR-14 in continuum mode, recoerding the slice from 28.0 to 28.5MHz:

Say HI to Juno

Thanks to the JPL people to this kind of activities for the Amateur Radio community.

73! eb3frn

Detecting Juno spaceprobe coming to Earth

This week he the enthusiasts os the space probes and the amateur-DSN are living a nice week dued the flyby of the Juno spacecraft. The flyby will be in the next October 9th.

Juno spacecraft

When the spaceprobes are very near to the Earth to do a flyby, the low gain (LGA)and medium gain (MGA) antennas are used. As this antennas not are in the central axis of the probe and it is rotating continuosly, you can see the rotational movement in the screenshoot:

Juno received from EB3FRN station

Perseids shower using graves radar

The past agoust I was build a passive radar to detect the Perseids meteor shwoer . The most easy way is locate a very away transmiter and try to se the echoes produces by the meteors ionizacion.

Perseids meteor Graves radar

To do the detector I used a rtlsdr receiver tuned to the Graves radar at 143.050 MHz, a ground planae VHF antenna and Baudline to display the scatters. Putting all toghetther using this script: