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Nonlinear junction detector

Posted: Thu Jan 10, 2019 2:32 pm
by Eagle72

Have 2 questions hope anyone can answer.

1. Im wondering if anyone know if its possible to build NLJD by using hackrf , what i know so far is it uses harmonic radar to detect electronics by transmitting highpower uhf 1-3.6 GHZ to specific nearfiled area... Since hackrf can transmitt up to 6ghz it should be possible or does it need to be fullduplex? Anyone who undertand this better know if this is possible by building 2 antennas and mount them above the hackrf and place it on a stick and connect to phone/lamptop to see reactions?

2. I have seen very intresting software used for sweeping for hidden rf-gsm bugs used for Delta x 100 which is quite expensive buts its software seems to be very good... is it possible to modify driver files to get it work with hackrf?

Delta X uses Signal Hound hardware and it seems as they have developed a opensource software from siggnalhoud which is avlivable for download... here : ... t-kit-sdk/

Here is the program for Delta X100 :

Re: Nonlinear junction detector

Posted: Mon Jan 14, 2019 6:54 am
by HighSNR
I think you would need full duplex unless you have a seperate signal source.

Re: Nonlinear junction detector

Posted: Fri Jan 18, 2019 6:59 pm
by Eagle72
Ok thanks for answer. I wish some programmer works to make one infinity device similar to hackrf but will full device tools.

Re: Nonlinear junction detector

Posted: Mon Jan 21, 2019 1:30 am
by snn47
uses harmonic radar to detect electronics by transmitting highpower uhf 1-3.6 GHZ to specific nearfiled area.
A simple explanation and DIY design can be found here ... g/mil/non/ and a more detailed Tutorial here Since both go back to Back the early 70's, when we didn't have that many electronic devices, I wonder how well such a device will operate in todays envrionment.

From what I understand you require sufficient radiated power to get pn junctions to generate harmonics that can be received by the attached receiver. The second source claims only a few feet of distance, so it cannot be called a RADAR since RADAR is Ranging and detection, RADAR requires a high gain narrow beamwidth antenna and operates receiving reflections on the Targets illuminated by the transmitter. RADAR operate in the >10 KW to 8 MW frequency Range.

You'd need an antenna that allows wideband operation of such a transmitter and receiver combination to detect the spurios leackage a device.

And most important
Without a liscense to radiate the signals you will interfere the primary user in frequency bands and will be in serious trouble.

Re: Nonlinear junction detector

Posted: Mon Jan 21, 2019 7:31 pm
by Eagle72
Thanks for detalied info.. i will check out the links.. Well since i hard about hackrf and seen lots of vidoes of moss i really like the idea he created hackrf and also portapack, it seems it has no limits if one can learn to understand and also program.. Mostly is for curiousnes not for i need a nljd but it seems very intresting. Even today agencys use NLJD uppgraded, i think back in 70.s it was 800mhz devices now its 3-6 ghz, and still they all need same law of power to transmitt/emitt power.