Re: [Discuss-gnuradio] Determining distance from OFDM signals

[Jonas Manthey]

Hi Andrew,

 

What do you mean by “information from the carrier data”? I’m no OFDM expert, but my intuition tells me that in a zero-IF architecture (which I assume your USRP has) any carrier phase information is lost. There’s some results when googling for “OFDM ranging” maybe that helps.

 

Cheers,

Jonas

 

From: Discuss-gnuradio [mailto:discuss-gnuradio-bounces+jonas.manthey=address@hidden] On Behalf Of Andrew Wolfram
Sent: Donnerstag, 6. Juni 2019 01:20
To: address@hidden
Subject: [Discuss-gnuradio] Determining distance from OFDM signals

 

Hi,

 

I'm trying to alter the file ofdm_txrx.py (https://github.com/gnuradio/gnuradio/blob/master/gr-digital/python/digital/ofdm_txrx.py) to get phase information from the carrier data so I can calculate an approximate distance between two USRP devices. Ideally I want to grab data from one of the blocks in the rx pipeline in the above python file after the frequency/timing corrections have been applied. I tried using the data after the serializer block, but it appears that this has no phase information. I tried with the equalizer block output but I'm not sure how to interpret its output data. For my particular payload with 300 occupied carriers and an fft size of 512 only the first 214 items of the equalizer output vector have any phase information, so I'm somewhat confused. Any ideas?

 

Thanks,

Andrew