devices, and even more daughterboards, in different revisions carrying different hardware, I think you should first narrow yourself down to a single platform (or a reasonably small selection of combinations); in the best case this setup would be something that you can actually test your calculations on using your own hardware - everything else would just roughly estimating

> > Sequence A: > 100 MHz (default) --> 1000 MHz --> 500 MHz > > Sequence B: > 100 MHz (default) --> 500 MHz --> 1000 MHz > > We are transmitting identical waveforms (non continuously, with prf of ~100 ms in external loopback with 30 dB attenuation) and estimate the PSD of the rx signal and apply a matched filter.

You can see in the attached image there is > > quite a bit of small magnitude anomalies for the second image (also > > errors are probably occurring a bit more frequently than I had > > previously estimated). > > > > To me this points to the issue being either something to do with the > > USRP or possibly with the TX chain blocks. > With a baseband magnitude

. >> best regards >> Jon >> >> 2017-10-16 17:17 GMT+08:00 liu Jong : >> >>> Hi,all, >>> >>> I'm using tow E312 to estimate the arrive time difference between >>> received signals.The >>> program is explained as follows: >>> >>> uhd::usrp::multi_usrp::sptr UsrpDev = uhd::usrp::multi_usrp::make(“”); >>> UsrpDev->set_time_source("gpsdo");

The carrier phase differences over these time intervals can be used to estimate the local oscillator frequency error. A multichannel receiver tracking several SVs should ensure that time intervals where cycle slips occur for all tracked SVs are relatively infrequent.

In reality, most receivers actually do an iterative solution where an estimate of the receiver's state vector (position, velocity, and clock error (frequency and rate of frequency)) is updated using a Kalman filter. The filter can also use the carrier frequency offset (since the PN code is coherent with the carrier).

I expect that, if 2 sources >are near zero phase, then it should only require <10s to estimate >the actual phase error within 1ps, or less. Anyone agree? > >I await & hope for constructive comments and/or corrections. I've done similar things, and can also get random errors in the femtoseconds, but only over short periods of time.

I measured the unloaded Q to be 313000, the loaded Q (using simple estimation) should be around 280000 in the circuit. (C0=2.5pF, R=20Ohm, C1=0.75fF, L=29.444mH, can be aquired at digikey). The spec for Rs was <130Ohms, I guess reality is much better :-) 9.

You could use leap second counter as a rought estimate to get the right 1024 week interval. Naturally, if leap seconds is no longer inserted that would break that algorithm. I wonder if this hint have been used by any receivers.. :) You can also use a CMOS backed clock, which many receivers have or there is an external option for a backup battery.

> Bruce Mike ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the response to your next post to save time: > Mike > Its well worthwhile estimating the additional jitter due to this > effect when using such a circuit to square up the output of an OCXO: > If the input signal characteristics are: > Frequency