Re: [Discuss-gnuradio] Ranging (measure distance) between two radios

[Oswald Berthold]

Mario Ruz <address@hidden> writes:

> Hello,
>
> This is my first post in the community. I have been thinking about doing this 
> question, but after having reviewed some of the theory with
> digital signal processing, usrp architecture and some approaches for 
> positioning/raning, I think I need to ask to the expert community,
> mainly to find a line of work and to know the restrictions for the 
> application we want to carry out.
>
> I would like to measure the distance between two radios at short distances 
> (we have two UN-210 and two XCVR2450 or 1 WBX and 1 DBSRX2,
> let's say to 1 m, 2m....up to for example 20 meters), starting from off-line 
> experiments and finishing with real time measures in line of
> sight. My questions are:
>
> - What would be, from your experience, the best approach to do this 
> (transmitted signal and digital processing in the receiver part), what
> accuracy should I expect in line of sight?
>
> I am looking mainly for a starting point, the signal structure to transmit 
> and the receiver structure. For example, one of the thoughts I
> have is a correlation in the receiver of a pseudorandom (spread spectrum) 
> transmited signal, this approach could serve to measure time of
> arrival by measuring the delay of the pseudo-noise code signal, when 
> comparing it with an exact copy at the receiver. Another approach I
> have seen is the estimation of the Channel impulse response (CIR), that maybe 
> (as far as i know) could serve also for estimating
> distances. I have seen that there is some code to do a correlation inside the 
> FPGA of the USRP1.
>
> So far my references are (which maybe can be helpul for those who are working 
> in the same field):
>
> - "Advancing Wireless Link Signatures for Location Distinction". Here, they 
> do not carry out ranging/positioning, but a change in the
> transmitter position is detected. In my case (in the case ranging is not 
> possible), to detect if a distance is crossed would be my
> objective  (e.g. the transmitter go closer than 1 meter to the receiver).
>
> - "RF Ranging for Location Awareness". In this dissertation they use an 
> arquitecture similar to the USRP hardware.
>
> As you can see what I am looking for is for some sort of radar/ranging 
> application and some starting point. Also, my questions are very
> generic for now and I apologize for it, mainly because I am still looking how 
> to focus the problem.
>
> Then, any help (references, similar work done) will be very useful.

uses custom hardware but might contain relevant bits. have not been able
to find a pdf though apart from through ie^3-xplore.

Radio localization in OFDM networks using the “round trip phase” 

Ohlemueller, T.  Winkler, F.  Grass, E.
Humboldt Univ. Berlin, Berlin, Germany 

2010 7th Workshop on Positioning Navigation and Communication (WPNC)


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