[USRP-users] Using two USRP N200 for capturing uplink and downlink signals

Nick Foster nick at ettus.com
Thu Jun 21 02:17:07 EDT 2012

If you are just capturing the uplink/downlink, and not actually acting as a
base station, the GSM frequency accuracy requirement doesn't apply. The
N200 should be perfectly well suited for this without an external reference.


On Wed, Jun 20, 2012 at 10:56 PM, Birhane Alemayoh <birhanea at gmail.com>wrote:

> Hi everyone,
> I am planning to capture and analyze GSM signals  using two USRP N200
> devices; one for downlink and one for uplink.
> USRP N200 can't run with external clock like 52 MHz which is suitable
> for GSM systems. However, these devices have the option for external
> 10MHz reference clock.
> I have three  questions:
> 1)
> Can I achieve  my objective of capturing GSM uplink and dwonlink
> signals by connecting the two USRP N200s using MIMO cable and by using
> the 10MHz reference clock for one USRP N200?
> Can the ClockTamer  be used an external clock reference to generate 10MHz?
> 2)
> What is the main function of this reference clock? I mean can this
> clock help for synchronizing the two USRP N200s in my application?
> 3)
> GSM standards put the following requirement "The BTS shall use a
> single frequency source of absolute accuracy better than 0.05 ppm for
> both RF frequency generation and clocking the timebase."
> How can this be achieved while using USRP N200?
> Thank you in advance!!
> --
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