Haven't used bladeRF, but I have used other LMS6002D-based radios with gr-air-modes, with some success. The problem is Mode S has a weak CRC and is thus vulnerable to spurious packets. That said, in practice spurious replies should be under 1% of your total. Experiment with gain and threshold settings -- your feedback should be nonunique ICAO numbers; in other words you're looking for multiple replies from the same aircraft. The "get_dupes.py" script in apps/ will take the output generated by gr-air-modes and parse it to tell you how many actual aircraft you've heard.
--n On Mon, Jan 27, 2014 at 2:35 AM, Ralph A. Schmid, dk5ras <[email protected]>wrote: > When having no clue about the data I should expect – how can I find out > about the real data, and how can I see what is decoded noise? I am using > the bladeRF, and to me most data looks wrong, too :) > > > > Ralph- > > > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Nick > Foster > *Sent:* Monday, January 27, 2014 9:43 AM > *To:* Cheng Chi > *Cc:* GNURadio Discussion List > *Subject:* Re: [Discuss-gnuradio] Help about using gr-air-modes > > > > The reason you're seeing lots of false packets is the use of a zero > threshold. Leave the -T 0 part out of the command line. Your other settings > are fine, although if you're indoors you probably aren't going to see much > data at all. > > > > I'll look into the timestamp issue and see if I can replicate it here. > > > > --n > > > > On Mon, Jan 27, 2014 at 12:40 AM, Cheng Chi <[email protected]> wrote: > > Hi Nick, > > > > The command line: > > {{{ > > modes_rx -T 0 -r 10000000 -s packet_float.dat > > }}} > > > > The setup: > > USRP + WBX + VERT900 Antenna, gain is set at 19 when recording the data. > > > > > > The output: > > {{{ > > usrp@ubuntu:~/gr-air-modes/apps$ modes_rx -T 0 -r 10000000 -s > packet_float.dat > > Using file source packet_float.dat > > Rate is 10000000 > > Using Volk machine: avx_32_mmx_orc > > (41 0.00000000) Type 0 (short A-A surveillance) from 8b11e3 at 43825ft > (speed <75kt) > > (31 0.00000000) Type 0 (short A-A surveillance) from 76ce83 at 19000ft > (Vertical TCAS resolution only) > > (38 0.00000000) Type 0 (short A-A surveillance) from 7805dd at 3025ft > (Vertical TCAS resolution only) > > (26 0.00000000) Type 4 (short surveillance altitude reply) from 53dd8d at > -1000ft (SPI) > > (25 0.00000000) No handler for message type 24 from d9a7dd > > (27 0.00000000) Type 0 (short A-A surveillance) from ee5e77 at 44475ft > (Vertical TCAS resolution only) > > (26 0.00000000) Type 0 (short A-A surveillance) from e2683e at 33850ft > (speed 1200-2400kt) > > (38 0.00000000) Type 0 (short A-A surveillance) from 7805dd at 3025ft > (Vertical TCAS resolution only) > > (26 0.00000000) No handler for message type 24 from df163e > > (26 0.00000000) No handler for message type 24 from 4dd8f4 > > (22 0.00000000) Type 0 (short A-A surveillance) from 3b8ec9 at 59100ft > (speed 75-150kt) > > (26 0.00000000) Type 0 (short A-A surveillance) from 9f6f91 at 18450ft > (speed 1200-2400kt) > > (28 0.00000000) No handler for message type 24 from c4b50b > > (31 0.00000000) Type 11 (all call reply) from 76ce83 in reply to > interrogator 0 with capability level 6 > > (31 0.00000000) Type 21 link capability report from 75008f: ACS: 0x10680, > BCS: 0xf600, ECS: 0x0, continues 0 ident 564 > > (23 0.00000000) No handler for message type 24 from 38f620 > > (26 0.00000000) No handler for message type 24 from d7a547 > > (29 0.00000000) Type 11 (all call reply) from 76aa6b in reply to > interrogator 0 with capability level 6 > > (26 0.00000000) Type 5 (short surveillance ident reply) from b49331 with > ident 7150 (aircraft is on the ground) > > (29 0.00000000) Type 5 (short surveillance ident reply) from 8f6b6a with > ident 7610 (SPI ALERT) > > (39 0.00000000) Type 4 (short surveillance altitude reply) from a69223 at > 32975ft (AIRBORNE ALERT) > > (25 0.00000000) Type 4 (short surveillance altitude reply) from acc9e9 at > 53700ft (aircraft is on the ground) > > (33 0.00000000) Type 0 (short A-A surveillance) from 8a01d4 at 18750ft > (speed 300-600kt) > > (32 0.00000000) Type 0 (short A-A surveillance) from 8a01d4 at 18750ft > (speed 300-600kt) > > (28 0.00000000) Type 0 (short A-A surveillance) from 601589 at 46725ft > (TCAS resolution inhibited) > > (27 0.00000000) Type 5 (short surveillance ident reply) from 4ba262 with > ident 2520 (SPI) > > (24 0.00000000) Type 21 link capability report from fba5fc: ACS: 0x250aa, > BCS: 0xe638, ECS: 0xa2, continues 6 ident 68 > > (25 0.00000000) Type 5 (short surveillance ident reply) from fbc939 with > ident 3620 (SPI ALERT) > > (24 0.00000000) Type 0 (short A-A surveillance) from 7e5086 at 111200ft > (speed 150-300kt) > > (24 0.00000000) No handler for message type 24 from 10b1ec > > (25 0.00000000) No handler for message type 24 from 1aba1c > > (24 0.00000000) Type 0 (short A-A surveillance) from 9d7554 at 10800ft > (speed 2400-4800kt) > > (23 0.00000000) Type 5 (short surveillance ident reply) from 9da024 with > ident 3540 (GROUND ALERT) > > (27 0.00000000) No handler for message type 24 from 9f8569 > > (24 0.00000000) No handler for message type 24 from 5da41f > > (25 0.00000000) Type 0 (short A-A surveillance) from ae194c at 48875ft > (speed 600-1200kt) > > (23 0.00000000) No handler for message type 24 from 11099d > > (30 0.00000000) Type 20 TCAS report from 76aa6b: (no handler for TTI=0) > at 11450ft > > (23 0.00000000) No handler for message type 24 from b7a19e > > (28 0.00000000) Type 20 link capability report from ef7118: ACS: 0x55278, > BCS: 0x954d, ECS: 0xb1, continues 14 at 51300ft > > (24 0.00000000) Type 0 (short A-A surveillance) from 7f4d04 at 13475ft > (speed 75-150kt) > > (32 0.00000000) Type 17 BDS0,9-1 (track report) from 8a01d4 with velocity > 406kt heading 150 VS 1984 > > (28 0.00000000) Type 21 link capability report from 8992dc: ACS: 0x100c0, > BCS: 0xe600, ECS: 0x0, continues 0 ident 9a0 > > (37 0.00000000) Type 20 TCAS report from 7805dd: (no handler for TTI=0) > at 3000ft > > (27 0.00000000) Type 0 (short A-A surveillance) from dc2ed9 at 45900ft > (speed 600-1200kt) > > (23 0.00000000) Type 4 (short surveillance altitude reply) from 2443b0 at > 59800ft (GROUND ALERT) > > (24 0.00000000) Type 4 (short surveillance altitude reply) from 3b1fc3 at > 3200ft (SPI) > > (21 0.00000000) Type 21 link capability report from d5ca0e: ACS: 0xda21, > BCS: 0xc923, ECS: 0xee, continues 8 ident 123e > > (22 0.00000000) Type 5 (short surveillance ident reply) from 5ad8b4 with > ident 728 (GROUND ALERT) > > (37 0.00000000) Type 17 BDS0,9-1 (track report) from 7805dd with velocity > 218kt heading 238 VS -1664 > > }}} > > > > Best regards, > > Cheng Chi > > > > On Mon, Jan 27, 2014 at 4:28 PM, Nick Foster <[email protected]> wrote: > > On Mon, Jan 27, 2014 at 12:23 AM, Cheng Chi <[email protected]> wrote: > > Hi Nick, > > > > Thanks for your quick reply! > > > > I have to use a 10M sampling rate in my case, but due to computer > constrain, modes_rx will cause overflow when used directly with -r > 10000000. I gauss it's because it's sampling data in float? I am using a > GPSDO with USRP. > > > > So I record data in short at 10M sampling rate, convert from short to > float and then input to modes_rx. The output looks like this: > > {{{ > > (27 0.00000000) Type 0 (short A-A surveillance) from dc2ed9 at 45900ft > (speed 600-1200kt) > > (23 0.00000000) Type 4 (short surveillance altitude reply) from 2443b0 at > 59800ft (GROUND ALERT) > > (24 0.00000000) Type 4 (short surveillance altitude reply) from 3b1fc3 at > 3200ft (SPI) > > (21 0.00000000) Type 21 link capability report from d5ca0e: ACS: 0xda21, > BCS: 0xc923, ECS: 0xee, continues 8 ident 123e > > (22 0.00000000) Type 5 (short surveillance ident reply) from 5ad8b4 with > ident 728 (GROUND ALERT) > > (37 0.00000000) Type 17 BDS0,9-1 (track report) from 7805dd with velocity > 218kt heading 238 VS -1664 > > }}} > > > > The timestamp are all zeros. > > > > This appears to be a bug. Can you paste the entire output of gr-air-modes? > > > > I'm also concerned by the data you've shown. There is only one real reply > in the above data -- the last one. The others are all spurious replies. Can > you tell me the command line you're using as well as the equipment setup -- > daughterboard, antenna, etc.? > > > > > > > > Another question is that if I use modes_rx, how to save the sampled > complex baseband signal? Is the data saved somewhere that I've missed? > > > > This is not something modes_rx is designed to do. I suggest instead that > you record samples to disk using uhd_rx_cfile, and then run modes_rx on the > saved file using --source=<filename>. > > > > --n > > > > > > Best regards, > > Cheng Chi > > > > > > > > > > On Mon, Jan 27, 2014 at 3:57 PM, Nick Foster <[email protected]> wrote: > > On Sun, Jan 26, 2014 at 11:48 PM, Cheng Chi <[email protected]> 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 > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > >
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