Saturday, October 23, 2010

Ladies and gentlemen, our "Wave"


This is a special post for me, there is just so much work behind it that I feel literally relieved :)

Figure 1: Wave GNSS front-end.

Luis and me went through a quantity of problems, but eventually this week we can claim that Wave works reliably and performs well.
So here it is, our vision of an industrial direct bandpass sampling, multi-constellation, multi-frequency receiver.

Figure 2: Wave digital board rev1.1 with LVDS, USB, and GigETH connectors exposed.

Figure 3: Wave RF board rev1.1 with dual band filters and variable gain amplifiers

I will not explain the theory behind it, just post a file captured with a Novatel GPS-704X antenna at NSL. With your favourite acquisition algorithm, you may find in there all the currently available satellite navigation signals. And if you know what we are talking about, you know you just need one parameter: f_S = 5.4e8.

By the way, we will be done soon with porting gps-sdr. Wave has already passed the overnight stress test with it on a 64-bit Ubuntu distribution.

Figure 4: gps-sdr processing GPS L1 as digitised and conditioned by Wave. Take a look at the spectrum of the signal on the left (we have a strong external interference at 1.369 MHz, we don't know who's responsible YET). And of course Luis' empty tea mug on the right, filled with champagne later that afternoon :)

We hope readers will find this tool as intriguing as we do. We like to think that we made one step towards the ultimate real-time all-frequencies, all constellations software receiver. Any takers of our challenge?

To be continued,
Luis and Michele