[USRP-users] Broken gpsdo or bad antenna?

Dario Lombardo dario.lombardo.ml at gmail.com
Tue Jun 26 11:58:46 EDT 2012

On Tue, Jun 26, 2012 at 4:52 PM, Nick Foster <nick at ettus.com> wrote:

> Hi Dario,
> I'm out of ideas regarding your reference. To me, it seems like
> *something* is locking, but not to the proper device.
> The last possibility I can see before a hardware failure is the
> possibility that your local cell tower actually is off 20kHz. Unlikely, but
> if it's your only point of reference I suppose it's possible.

No, it's not. I've run kal in scan mode and the result is more or less the

 $ ./kal -s 900 -x
linux; GNU C++ version 4.5.1 20100924 (Red Hat 4.5.1-4); Boost_104400;

-- Opening a USRP2/N-Series device...
-- Current recv frame size: 1472 bytes
-- Current send frame size: 1472 bytes
-- Detecting internal GPSDO.... Found a Jackson Labs GPS
-- found
-- Setting references to the internal GPSDO
-- Initializing time to the internal GPSDO

UHD Warning:
    The hardware does not support the requested RX sample rate:
    Target sample rate: 0.270833 MSps
    Actual sample rate: 0.271739 MSps
kal: Scanning for GSM-900 base stations.
        chan: 8 (936.6MHz - 12.533kHz)  power: 8062.48

        chan: 11 (937.2MHz - 12.430kHz) power: 13724.73

        chan: 37 (942.4MHz - 12.116kHz) power: 13138.43

        chan: 85 (952.0MHz - 10.961kHz) power: 22605.52

        chan: 92 (953.4MHz - 10.885kHz) power: 44800.99

        chan: 112 (957.4MHz - 10.786kHz)        power: 31025.00

Today I've conducted a test with a counter. GPSDO is completely isolated
from the mainboard except for the power supply, sma pps is floating and
clock is connected to counter. Counter gives me around 10.000.200 Hz. That
confuses me totally...
Why kal gives me 10 kHz of error??
Why gpsdo has a so bad clock? It is not enough for GSM :(...

I want to go on a roof to have a clear signal.
Updates will follow.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20120626/192597d8/attachment-0002.html>

More information about the USRP-users mailing list