[USRP-users] Measuring TDOA for Localization

Nate Temple nate.temple at ettus.com
Fri Jan 10 13:40:23 EST 2020

Hi Richard,

To clarify, are you using a common Octoclock, with the 3 X300's in the same
location, or separate locations with 3x Octoclocks? Do you have equal
length cables to the antennas and does the rest of the system match ?

What is your RX frequency ?

What daughterboard are you using?

You may want to try using a decimation factor that will produce an
non-fractional host sample rate, instead of 200e6/22 = 9090909.09090909_
MHz. Does running at 10 MS/s sample rate produce any difference in the

Nate Temple

On Thu, Jan 9, 2020 at 4:08 PM Brian Padalino via USRP-users <
usrp-users at lists.ettus.com> wrote:

> On Thu, Jan 9, 2020 at 6:45 PM Richard Bell <richard.bell4 at gmail.com>
> wrote:
>> 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?
> I'd think the group delay should be pretty consistent - at least within
> 10's of nanoseconds of each other if the setup is identical.
> What type of variation are you seeing when you perform your cross
> correlations?  How much variation are you able to handle?
> Brian
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