Re: [Discuss-gnuradio] Help about using gr-air-modes

[Nick Foster]

On Sun, Jan 26, 2014 at 11:48 PM, Cheng Chi <address@hidden> wrote:

Hi,

I am using gr-air-modes for decoding the air plane signal with USRP. I've successfully used the "modes_rx" and "modes_gui" for decoding the mode-S packets.

However, it seems that the modes_rx or modes_gui can't provide the timestamp of the mode-S packets being decoded. Is there any option that I can set to timestamp the mode-S packet? The reason I want this timestamp function is that I want to know the decoded packet data correspond to which part of the raw data (complex baseband data samples). 

If you're using a USRP, you should be getting a timestamp. It's the second number printed, as in the following:

(-14 1.29258827811) Type 0 (short A-A surveillance) from ab2984 at 3000ft

If you are using a GPSDO with your USRP, the printed time will be in UTC seconds. Otherwise, it will be in seconds since the application started running.

--n

 

Thank you for any help you can provide in this situation.

I found that there's a file called "air_modes_preamble.cc" seems to provide the timestamp function. Does anyone know how to use this file separately? 

Best regards,

Cheng Chi

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