Antenna array vs jamming

Signal processing; Software GNSS Receivers; bugtracker and your suggestions
amungo coder
Posts: 22
Joined: Tue Sep 06, 2016 5:37 am

Antenna array vs jamming

Postby amungo coder » Sat Dec 24, 2016 10:59 am

Hello!

I've just make an experiment. I've got a RF generator to make a noise in L1. I used F = 1575MHz

I connect nut4nt 4-channel board with RA4 antenna array and couldn't find a correlation when a generator is on.
You can see a spectrum with synthetic noise (from a generator).
2016-12-24 18-42-52 Figure 1.png
2016-12-24 18-42-52 Figure 1.png (93.91 KiB) Viewed 2607 times


And my software can't see any sats (I should see five from my window)
.[ 2][ 2000 ][ 49596 ] corr = 2791 k = 2.0 (mean 1400)
.[ 6][ -3500 ][ 34585 ] corr = 2901 k = 1.5 (mean 1914)
.[ 7][ -2500 ][ 30721 ] corr = 3019 k = 1.7 (mean 1801)
.[ 9][ 2500 ][ 26770 ] corr = 3156 k = 1.7 (mean 1861)
.[30][ -2500 ][ 34273 ] corr = 3903 k = 1.8 (mean 2210)

Then I calculate something in matlab: corrcoef() between first channel and three others. And I sum all four channels with that coefficients.
And the jamming is gone (see screenshots attached, RED is a summed signal).
2016-12-24 18-36-47 Figure 1.png
2016-12-24 18-36-47 Figure 1.png (44.07 KiB) Viewed 2607 times

The results from software - all five satellites are visible!
**[ 2][ -1488 ][ 52789 ] corr = 1493 k = 4.0 (mean 377)
**[ 6][ -2677 ][ 48406 ] corr = 1643 k = 4.9 (mean 339)
**[ 7][ 2974 ][ 25913 ] corr = 2881 k = 8.6 (mean 334)
**[ 9][ 2989 ][ 753 ] corr = 1587 k = 3.8 (mean 423)
**[30][ -2545 ][ 34268 ] corr = 1459 k = 3.1 (mean 471)

There are signals I use.
https://goo.gl/J6hkMk
Best regards,

Viktor
Amungo Navigation

User avatar
itsar
Posts: 14
Joined: Tue Sep 06, 2016 5:01 am

Re: Antenna array vs jamming

Postby itsar » Tue Dec 27, 2016 12:26 pm

Oh, very good discussion about this experiment - https://www.linkedin.com/groups/13506339

amungo coder
Posts: 22
Joined: Tue Sep 06, 2016 5:37 am

Re: Antenna array vs jamming

Postby amungo coder » Wed Jan 04, 2017 2:03 am

Hello!

A day ago I've got a 'secret' Amungo's small antenna array. And I dumped 10 seconds of L1 GPS for you. It's about 10 seconds of signal and it's jammed only near the end (after 8th second at least).

You can download signals from nut4nt+secretRA4_array from here:
https://goo.gl/kXqlO6

I am going to process it in few days after that merciless new year holidays :)

Ans some photos:

'laboratory bench' :)
IMG_20170103_121702_1483435848635.jpg
IMG_20170103_121702_1483435848635.jpg (55.19 KiB) Viewed 1884 times


Secret small RA4 array with nut4nt
IMG_20170103_120842.jpg
IMG_20170103_120842.jpg (723.6 KiB) Viewed 1884 times


Small RA4 array
IMG_20170103_120641.jpg
IMG_20170103_120641.jpg (543.57 KiB) Viewed 1884 times


Small RA4 array
IMG_20170103_120630.jpg
IMG_20170103_120630.jpg (538.06 KiB) Viewed 1884 times


RF generator
IMG_20170103_121234.jpg
IMG_20170103_121234.jpg (573.95 KiB) Viewed 1884 times
Best regards,

Viktor
Amungo Navigation


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