[USRP-users] Measuring TDOA for Localization

Nate Temple nate.temple at ettus.com
Fri Jan 10 13:41:54 EST 2020


I meant to include this link with regards to the same rates in my previous
email:
https://files.ettus.com/manual_archive/v3.15.0.0/html/page_general.html#general_sampleratenotes

On Fri, Jan 10, 2020 at 10:40 AM Nate Temple <nate.temple at ettus.com> wrote:

> 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
> result?
>
>
> Regards,
> 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
>>
>>> _______________________________________________
>> USRP-users mailing list
>> USRP-users at lists.ettus.com
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>
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