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I am working on wideband direction finding algorithms for passive sensors.

I started with Music algorithm. For practical reasons, the spacing can not be maintained lambda/2. For greater antenna spacing, grating lobes appear.

I found some algorithms for ambiguity resolving. However, I only found algorithms for resolving ambiguity in presence of only one source signal (eg. one transmit signal). Most of the algorithms (multiple baseline algorithms) take phase difference value for multiple baseline and determines/resolves the angle of arrival value (for one source).

For my application, I am looking at resolving ambiguity for multiple sources with one baseline consisting of 4 to 8 elements (receivers).As for Music algorithm, with 4 sensors its possible to determine 3 sources (maximum) unless any rank enhancement algorithm is applied.

Is there any algorithm which resolves such ambiguity issue?

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  • \$\begingroup\$ Hm, don't fully get your point. If you have a signal composed of multiple signals, can't you just extract a single one of these and run your algorithms that run on only one signal with that? \$\endgroup\$ – Marcus Müller Apr 6 '17 at 16:18
  • \$\begingroup\$ Without clear specs on all input signals ( BW, dB , SNR , sensor type and output , amplitude, frequency coherence, FFT, noise blocking phase detection, purpose of your question is severely lacking input. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Apr 6 '17 at 16:34
  • \$\begingroup\$ A very good question. However, you might be better off asking in dsp.stackexchange.com \$\endgroup\$ – Enric Blanco Apr 6 '17 at 16:37
  • \$\begingroup\$ Thanks for the replies. Primarily, I am trying to perform direction finding from freq 400 MHz to 6 GHz. I am using software radios as hardware. I am using X310+UBX combination. The bandwidth I am using is 500 KHz. So I am switching and tuning to a specific frequency and perform direction finding. For my application, I have the issue with coherent sources. I am expecting at least 2 coherent sources. Now, in this case tuning at specific frequency is not really helping. So, could you tell me how to resolve ambiguity for such a scenario or how should I proceed. \$\endgroup\$ – Sanjoy Basak Apr 6 '17 at 19:20
  • \$\begingroup\$ Frequency stability of SDR must be ultra-stable or locked to some reference with low phase noise than your coherent sources. Also antenna phase is critical and multipath distortion must not occur. When I did this I used precision Analog radios and high gain helix antenna to sources with <1e-10 coherent source and base station frequency for Doppler range and azimuth. CNR and SNR must be high for accurate correlation. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 6 '17 at 3:57

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