UmTRX aka OpenBTS HW update

Jean-Samuel Najnudel - BJT PARTNERS SARL jsn at
Tue Oct 11 13:11:57 UTC 2011

Hi Alexander,

I looked at the schematics and PCB. I did not notice anything bad. However,
I am not really able to check everything.

Anyway, I just have two questions.
1/ There is a CLKIO connector. As I can see on the schematics. We can set
this as a clock output (master) or input (slave). This looks perfect if we
want to synchronize 2 boards together (1 master output connected to 1 slave
input). If we need to synchronize 3 boards together (trisector
configuration), how could we connect them together ? Can we split the clock
output signal to connect it to the 2 slave inputs ? If yes, everything is
fine. If not, we might need 1 ouput and 1 input on the board (instead of 1
output or 1 input) to allow us to daisy chain the boards. What do you think
2/ On Image2, I can see 3 components outside the board near the 6 pin
connector. Is this normal ?

Please let me know about these two points.

Best regards.


On Tue, Oct 11, 2011 at 4:41 AM, Alexander Chemeris <
alexander.chemeris at> wrote:

> Hi all,
> We're going to start the last iteration of PCB layout today and thus
> if you have any comments, it's better to write them right now.
> Otherwise it will be harder to incorporate them.
> On Fri, Oct 7, 2011 at 02:28, Alexander Chemeris
> <alexander.chemeris at> wrote:
> > The latest version is attached. Looking forward to your comments.
> >
> > Andrey will try to add one more converter to support 10-14V to be able
> > power it from batteries in the next revision.
> >
> > Regarding test-points - we'll add more test points for LMS. Robin, if
> > you could recommend any specific points to check, we'll try to add
> > them.
> >
> > --
> > Regards,
> > Alexander Chemeris.
> >
> --
> Regards,
> Alexander Chemeris.
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