-1
$\begingroup$

I am working on the ranging signal which is similar to the time delay estimation part for the signal processing, and I am looking for good sources which can help me to answer these question:

  1. When you receive the signal and you want to determine time domain, what would you use of that signal?

  2. You receive the signal, you know what the signal transmitted, you know where I receive very first sample, what would you do to determine time domain for that situation?

If anyone who has been seen or worked in this topic, please help me to provide the resources or give me some ideas.

$\endgroup$
  • 1
    $\begingroup$ "... you want to determine time domain". What do you mean by that? "...you know where I receive very first sample, what would you do to determine time domain for that situation?" What do you mean by "determine the time domain"? In general, for time-delay estimation a cross-correlation approach is usable, but I dont know if this is what you are asking for. $\endgroup$ – Maximilian Matthé Feb 28 '17 at 8:19
  • $\begingroup$ Please clarify the details of your ranging signal, for instance are you using FMCW that may be most applicable to a RADAR application, or are you using a PRN sequence such as GPS, pulses such as LORAN, etc... $\endgroup$ – Dan Boschen Feb 28 '17 at 12:28
  • $\begingroup$ @DanBoschen : you are right that i am using FMCW which is most applicable. If so, could you please give me some information for the good resources? Thank you. $\endgroup$ – Nate Duong Feb 28 '17 at 13:51
  • $\begingroup$ @MaximilianMatthé : I am trying to do some research about time delay estimation, but they are all information i know, because I am new in signal processing. For time-delay estimation a cross-correlation approach is usable, I am agree with that. Could you please give me some information for the good resources? Thank you. $\endgroup$ – Nate Duong Feb 28 '17 at 13:56
1
$\begingroup$

For ranging in an FMCW application, a frequency ramp is transmitted through the antenna but also provided coherently to a mixer (multiplier) that mixes with the received (reflected signal) producing a beat signal at a frequency that is proportional to the range. Thus the range can be derived from an FFT on the digitized output of the mixer.

Note that in doing this operation we are essentially computing the cross correlation between the transmitted and received signal, since the cross correlation is a multiply and accumulate (integrate) operation (and in the analog a typical analog downconverter is a mixer followed by a low pass filter-- essentially the same thing since accumulation and integration are low pass operations).

For more details on this see the Sawtooth Modulation section here:

https://en.wikipedia.org/wiki/Continuous-wave_radar

and more resources here:

https://www.mathworks.com/help/phased/examples/automotive-adaptive-cruise-control-using-fmcw-technology.html

https://www.slideshare.net/tobiasotto/principle-of-fmcw-radars

http://bu.edu.eg/portal/uploads/Engineering,%20Shoubra/Electrical%20Engineering/2443/crs-14023/Files/FM%202.pdf

$\endgroup$
  • $\begingroup$ I am sorry, but I hope you can answer me one more question, in the document says: "The satellites in orbit provide the ranging signals and data messages to the user equipment", so How do I determine the ranging signals? $\endgroup$ – Nate Duong Feb 28 '17 at 15:56
  • $\begingroup$ What satellites are these? I was describing an FMCW radar application; which does not sound like what you are dealing with. $\endgroup$ – Dan Boschen Feb 28 '17 at 17:02
  • $\begingroup$ I also tried to understand on the GPS satellites. $\endgroup$ – Nate Duong Mar 1 '17 at 14:09
  • $\begingroup$ Ok well GPS satellites do not use FMCW but use direct-sequence spread spectrum with Gold Codes. I have a gold code generator available from the MathWorks file exchange site that has a demo application in how the ranging works: mathworks.com/matlabcentral/fileexchange/… $\endgroup$ – Dan Boschen Mar 1 '17 at 15:15
  • $\begingroup$ Actually if you look at my other files there (I only have three) there is one called "Joint Frequency and Delay Correlation" that uses FFT's to efficiently extract the delay parameter, and that is the one that has demo code. The first one I mentioned creates the satellite signals $\endgroup$ – Dan Boschen Mar 1 '17 at 15:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.