Re: [Discuss-gnuradio] ask : USRP Mode-S/ADS-B project

[Eric A. Cottrell]

Bino Oetomo wrote:
> Hello
> Eric A. Cottrell wrote:
> > Hello,
> >
> > The code is still a work-in-progress.  The hardware used, the USRP 
> > and DBSRX board, costs as much or slightly more than the RadarBox or 
> > SBS-1.  It might be possible to do a simplified hardware board but I 
> > am not a hardware engineer.  Mode-S/ADS-B has a 1 Megabit symbol rate 
> > which is way above what a sound card can do.
> Nice to hear that it's still in active stage.
>
> Obout the Receiver cost : I understand that, still ...
> ++ with this we can do some OpenSource and flexible solution
> ++ Hope ettus will consider to produce 1 port board. I reallize that 
> the price cut will not that big ... since the core component (i.e : 
> FPGA) still the same ..... but there is a "cut" anyway :)
It would be likely be in the 500 dollar range as it would be similar to 
a RF Space SDR-IQ.  It may be possible to optimize the design further so 
it will only decode Mode-S but that would preclude decoding the future 
UAT transmissions.  The FAA plans to do TIS-B over UAT.  TIS-B would 
provide information on Mode S and Mode A/C aircraft.

There are some interesting hardware available or soon to be available 
that could reduce the coast.  One interesting chip is the TI OMAP series 
that combines an processor and DSP on one chip.  It may be possible to 
use one of the on-board devices to digitize the waveform but a RF front 
end is still needed.

> About Symbol rate : hmmm what about DVB rx card .... i'm not sure if 
> we can customize their demodulation to handling mode-s/ads-b ... but 
> they capable in handling up to 45 megabit/sec symbolrate , and capable 
> of handling freq around 1 Ghz cmiiw.
> Arrrggh ... looks like we need to do firmware work (too many work).
>
> Thanks for your enlightment
> -bino-
DVB receivers cover the same frequency range but are designed for larger 
signal levels from the LNB.  DVB uses QPSK.  Newer receivers have front 
end chips that take the RF and output the digital mpeg transport 
stream.  The DVB Rx board for the USRP uses a DVB tuner chip but it is 
preceded by an amplifier.  Some Video Cards do have an extra ADC that 
may be useful but you need more components for a complete system.

Another avenue is alternate firmware for the SBS-1 or Radarbox much like 
the Rockbox project for MP3 players.  I suspect that both units use soft 
microprocessors in the FPGAs.

I try to keep track of hardware as does several others so if there is a 
lower cost solution it will be found.

73 Eric