Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Passive radar with $16 dual coherent channel rtlsdr dongle receiver  (Read 17213 times)
AG1LE
Member

Posts: 137


WWW

Ignore
« on: September 27, 2013, 07:02:36 PM »

Check this out:  passive radar with $16 dual coherent channel receiver: http://kaira.sgo.fi/2013/09/passive-radar-with-16-dual-coherent.html

You can see meteorites, airplanes and other interesting things:


Juha Vierinen has some really cool SDR stuff cooking at MIT Haystack Observatory!

73
Mauri  AG1LE
Logged
K5TED
Member

Posts: 747




Ignore
« Reply #1 on: September 27, 2013, 07:13:30 PM »

Check this out:  passive radar with $16 dual coherent channel receiver: http://kaira.sgo.fi/2013/09/passive-radar-with-16-dual-coherent.html

You can see meteorites, airplanes and other interesting things:


Juha Vierinen has some really cool SDR stuff cooking at MIT Haystack Observatory!

73
Mauri  AG1LE

Unless you know the distance from the transmitter to the target, the results will be inaccurate. Even if the transmitter is synchronized to an absolute time standard.

Radar specialists, I won't be hurt if you correct me..  Grin
Logged
AG1LE
Member

Posts: 137


WWW

Ignore
« Reply #2 on: September 27, 2013, 11:56:01 PM »

Unless you know the distance from the transmitter to the target, the results will be inaccurate. Even if the transmitter is synchronized to an absolute time standard.
Radar specialists, I won't be hurt if you correct me..  Grin

For $16 cost some inaccuracy may be tolerated perhaps? Smiley 

You can read more on underlying principles and mathematics from his PhD theses over here http://www.sgo.fi/~j/intro.pdf.
There is another interesting experiment on building a radar image of lunar surface using UHF transmitter at 32 cm wavelength.
Not every ham has access to 2 MW transmitter, though Grin
Logged
KA4POL
Member

Posts: 2028




Ignore
« Reply #3 on: September 28, 2013, 11:08:24 PM »

There is another interesting experiment on building a radar image of lunar surface using UHF transmitter at 32 cm wavelength.
Not every ham has access to 2 MW transmitter, though Grin
I use the 400 nm to 700 nm wavelengths with a 1.367 W/m^2 transmitter to build my lunar surface images, i.e a telescope  Grin
Logged
KE7TMA
Member

Posts: 471




Ignore
« Reply #4 on: October 14, 2013, 07:44:26 PM »

Check this out:  passive radar with $16 dual coherent channel receiver: http://kaira.sgo.fi/2013/09/passive-radar-with-16-dual-coherent.html

You can see meteorites, airplanes and other interesting things:


Juha Vierinen has some really cool SDR stuff cooking at MIT Haystack Observatory!

73
Mauri  AG1LE

Unless you know the distance from the transmitter to the target, the results will be inaccurate. Even if the transmitter is synchronized to an absolute time standard.

Radar specialists, I won't be hurt if you correct me..  Grin

A question:  For a person just interested in doing this for fun, for a minimum amount of money and with only a small time investment, what sort of accuracy would you specify?  You could write this guy a letter explaining to him that his homemade radar isn't up to your exacting minimum standard of quality.  I bet he'd stop right away, shamed by the slapdash job he did and awed by the amazing accuracy of your own home-made radar gear which of course, you would eagerly show him and the rest of us.

Right?
Logged
WV4I
Member

Posts: 136




Ignore
« Reply #5 on: October 22, 2013, 05:08:30 AM »

A new application for the cheap, down to $11 shipped on Ebay, RTLSDR usb sticks. Be sure to get RTL2832/820t or rtl2832/e4000 only. Can usually read markings on chip if cover off photos. Nice post!
Logged
K4FMH
Member

Posts: 255




Ignore
« Reply #6 on: November 05, 2013, 08:51:58 AM »

Thanks for reporting this to this Forum! Really cool experimental work. Some of that tall oaks from little acorns grow potential...

73,

Frank
K4FMH
Logged
ZENKI
Member

Posts: 960




Ignore
« Reply #7 on: December 18, 2013, 02:41:42 AM »

How about 9 X RTLSDR receivers. 9 X active FET active antennas and some software that can locate any station on the planet with a 0.5 degree accuracy.
That should be possible. Hams could deliver a DSP based wordwide direction finding network that could pinpoint anyone with dares to transmit one CW dit.
This could be implemented in Mathlab using the many public domain algorithms  like MUSIC and ESPRIT. This same system could deliver a nice QRM beam steering system.

The issue is that all 9 receivers should be phase coherent.

http://www.g4axx.com/HF_Radio_Direction_Finding.pdf
Logged
W6RMK
Member

Posts: 656




Ignore
« Reply #8 on: December 21, 2013, 06:46:43 PM »

Be a bit of challenge getting that kind of accuracy on a skywave signal.
Logged
G7MRV
Member

Posts: 480


WWW

Ignore
« Reply #9 on: February 02, 2014, 10:48:55 AM »

How about 9 X RTLSDR receivers. 9 X active FET active antennas and some software that can locate any station on the planet with a 0.5 degree accuracy.
That should be possible. Hams could deliver a DSP based wordwide direction finding network that could pinpoint anyone with dares to transmit one CW dit.
This could be implemented in Mathlab using the many public domain algorithms  like MUSIC and ESPRIT. This same system could deliver a nice QRM beam steering system.

The issue is that all 9 receivers should be phase coherent.

http://www.g4axx.com/HF_Radio_Direction_Finding.pdf

I have to say, I can see the potential in that! Maybe not down to HF,a nd not with 'worldwide' coverage, but a simple antenna, a simple dongle based receiver, and lots of them installed in lots of remote but in some way internet linked places, and you'd have a very fast VHF/UHF DF network that could be used to pinpoint almost any signal.

I have a RTL2832/820t dongle on order to have a play with
Logged

M0HCN
Member

Posts: 473




Ignore
« Reply #10 on: February 03, 2014, 01:00:31 PM »

Quote from: ZENKI
This could be implemented in Mathlab using the many public domain algorithms  like MUSIC and ESPRIT. This same system could deliver a nice QRM beam steering system.
It didn't make it in the end but there was talk of such a rig being demoed at the 30C3 hacker convention in Hamburg over Christmas.

The idea was to go one better and use the DAB broadcast transmissions (Which are lovely convenient pulses with defined gaps) together with some beamforming and correlation games written to run on a graphics co processor to implement a full up passive radar system.

Next year?

Some of those dongles just scream to have their rock replaced with an external clock input, shouldn't be hard to pull off.

Regards, Dan.
Logged
CHRISTOFERO
Member

Posts: 23




Ignore
« Reply #11 on: February 24, 2014, 09:48:52 PM »

This was so very cool because all of us were ruminating for at least a year or so whether it would be possible but nobody actually did it until this person did, and he showed that it was really, really easy! He's even used three rtlsdrs at the same time.

Note that the USB timing is still quite iffy.

One particular R820T dongle that I have is substantially more frequency stable than all my others, I think it has a better crystal. Its the white one with the PAL connector.

Note to the person who was talking about beam forming. The problem is the timing on the USB bus, so, I think the best way to deal with that would be to use some very weak signal inside of the passband to synchronize all of them. If you go to the osmo-sdr mailing list there is a recurrent theme discussing this issue. A Chinese software developer who has done some neat stuff with the rtlsdr and cellphones has proposed some ideas. there was also a fair amount of discussion on the gnuradio mailing list and one of the linrad forums about timing synchronization.

There is also a project gnss-sdr that is dealing with the same issues. there I read that there is some emergent standard which hopes to develop a timecode which will be supported across multiple platforms and software which will make it possible to do more of that kind of stuff that involves multiple SDR synchronization. Leif Asbrink of Linrad is really interested in multiple dongle synchronization, I think, to use in adaptive noise reduction. If you guys want to help him he would really like you to send him captures (using any SDR and Linrad) of your most problematic RFI. If the RFI has a local source it might be possible at some future date in the not too distant future, to null it out.
« Last Edit: February 24, 2014, 09:58:12 PM by CHRISTOFERO » Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!