[USRP-users] Measuring TDOA for Localization

Richard Bell richard.bell4 at gmail.com
Thu Jan 9 18:45:41 EST 2020

No I don't need to know phase information. I'm cross correlating the pairs
of receivers and the location of the peak gives me the TDOA. If the
hardware chains across different radios introduce different delays, that
would invalidate the TDOA measurement. So long as the delay is the same
through all the hardware chains, the TDOA estimate will be accurate. Can I
assume the hardware delay through X300 USRPs with the same FPGA image and
set to the same sampling frequency will be the same?

On Thu, Jan 9, 2020 at 12:51 PM Brian Padalino <bpadalino at gmail.com> wrote:

> On Thu, Jan 9, 2020 at 12:14 PM Richard Bell via USRP-users <
> usrp-users at lists.ettus.com> wrote:
>> Hello,
>> I'm working on a TDOA based localization platform using 3 USRP X300's as
>> receivers. I have them synchronized with a 10 MHz ref and PPS signal
>> generated by an OctoClock. However, I'm having trouble getting reliable
>> localization performance through this system. My TDOA measurements are not
>> what I would expect for the geometry I'm using.
>> If I have the USRPs flashed with the same FPGA image and I use the same
>> sample rate (i.e. 200e6/22 = 9.0909 MHz) across them all, is it possible
>> the hardware could still be introducing different delays through each
>> receiver?
> Did you calibrate their phases using some type of calibration signal such
> that you know the relative phase offsets of each radio to each other?
> Do you need to not know this information?
> Brian
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