Today i got my OpenBTS working stable the first time. I also had success
running it 52Mhz. It works great now - after weeks of trial and error.
I have several RFX boards here. Two RFX900, Two RFX 1800 and a few
others... I first tryed the two RFX 1800 Boards with 1800 Mhz - had no
success at all. Then i found out that i can use a RFX 1800 as RFX900.
Surprisingly it works without any modification of the EEprom content ;-)
All in all it worked very sporadicly.
I always thought that the problems would come from the instable clock on
the USRP. So i got a more accurate clock (FA-SY, calibrated against an
Rubidium frequency standard). The phones saw the the network - but could
not log in. In the log files i could see only sometimes any reaction to
the login attempt - my OpenBTS seemed to be completely deaf.
I tested the 52Mhz clock - did not work, saw no carrier.
Then i took a closer look to my boards. There were from different
revisions because the CCCB bought the USRP a few years ago and i bought
one RFX900 and one RFX1800 recently to do my OpenBTS experiments.
The difference between the two boards are basicly that one has a 64Mhz
crystal and one not:
So i inserted my new RFX900 Board as transmitter and the new RFX1800 as
receiver and it started working! Even with 52Mhz!
I assume that my old boards still run from their own oscillator instead
from the more accurate master oscillator and that this caused the
problems i had before.
Now my question is if anyone of you had a semilar experience and is it
possible to modify the old boards that they run on the master oscillator.
From: Matt Ettus <matt@et...> - 2010-05-22 19:57:03
On 05/22/2010 10:06 AM, dexter wrote:
> I assume that my old boards still run from their own oscillator instead
> from the more accurate master oscillator and that this caused the
> problems i had before.
You need to follow the instructions here to make all of your older
boards into MIMO_B versions: