2950R - octoclock vs reference sharing

[ozan_icin]

Hello,

I need some comparison info for synchronizing multiple USRPs for our further MIMO and direction finding projects. 

For a 4 channel phase coherent recevier we are planning to use 2 x USRP-RIOs.  

We have the option of using Octoclock(or Octoclock-G) for high frequency accuracy and phase aligment performance, together with 2 x 2940R. Which provides 25ppb frequency accuracy.

Can we acheve the same performance using 1 2940R and 1 2950R? since 2950R have OCXO(providing 25ppb accuracy) and can export it via Ref out  to REF in of the 2940R. Does this configuration give the same performance comparing to Octoclock? And If we need GPS lock, can we really achieve 1ppb frequency accuracy for both USRPs via this method. Will we face any other problems except the constant phase offset between the devices?

In other words we need to now which is the best method in such kinds of applications for phase coherency:

                      -Using Octolock as the clock source for all the devices? or

                      -Buying one USRP with GPS clock and sharing this reference with other USRPs. 

Thanks 

Ozan

[ErikL]

Ozan -

Great question. Use the Octoclock-g with equal length cables. It will make implementation much easier.

There are some additional strategies you will need to consider depending on whether you're implementing a MIMO system or direction finding system.

[ozan_icin]

Hi Erik,

Thank you for your quick response.

However I will appreciate for some info about the performance of the the configuration with 1 2950 and 1 2940(In fact the same situation is valid for 2930 and 2920)

Ozan

[ozan_icin]

Any comment?