Friday, February 20, 2009

Ticking the last box: Glonass L1

We had to wait long enough for some RF filters. Half a hour after receiving them, the Maxim MAX2769 which is fitted on our NSL USB dongle tuned correctly on Glonass frequency. I had to quickly make up a bit of Matlab code, and off I went acquiring Russian birds over Nottingham skies.
Result: 8 satellites. Pictures attached.

Fig. 1: The signal characteristics show some interference peak, and the gain should to be increased a bit.

Fig. 2: The typical histogram of acquired channels. This time is Glonass.

Some details of the channels:

Fig. 3: Details about the individual channels.

I hope the MAX2769 has no secrets any more :)

The next post will be something new, about a new exciting Software Defined Radio GNSS receiver!


Sunday, February 1, 2009

An interesting signal modulation

With GIOVE-B, the second satellite of the IOV Galileo constellation, a new modulation is being experimented, the CBOC(6,1,1/11).
With the CPLD version of NSL dongle and a bit of software, I did get the result below.. is not smooth and as beautiful as Septentrio's one (, but it demonstrates some interesting capabilities already.

Fig.1: Tracking the CBOC(6,1,1/11) with a BOC(1,1) replica, a BOC(6,1) replica, and the sum of of the two.

In a couple of week I would like to show something else... let's see.