Re: [Openbts-discuss] B210 - how to change antenna ports?

[Ralph A. S. d. <ra...@sc...>]

Thanks a lot! Yes, it may be useful to include some possibility to hand over
such options during compile process...or at least comment a possibility in
the sources how to change such things.

The story behind it, ESD killed the antenna switches in my B210, so while
waiting for the spare parts I circumvented the switches with reseating the
capacitors (this path is already prepared on the PCB). When unsoldering the
old parts I found out that the PCB sucks up all the heat I was able to
produce, so I decided to let the rework be done by a pro. Now the switches
are fine, but it seams in the few hours without switches I also killed
somehow the PA. So I am waiting for the PA MMIC now, what has some lead time
and a minimum amount of 20 pieces that I had to order, and my tests are
limited to -10dBm or so for the moment :) What a mess!

I installed ESD protection diodes right at the antenna connectors, hopefully
this helps. For sure some design flaw to leave out such protection...

Ralph.

> -----Original Message-----
> From: Tom Tsou [mailto:to...@ts...]
> Sent: Monday, March 9, 2015 7:26 PM
> To: Ralph A. Schmid, dk5ras
> Cc: ope...@li...
> Subject: Re: [Openbts-discuss] B210 - how to change antenna ports?
> 
> On Fri, Mar 06, 2015 at 11:38:15AM +0100, Ralph A. Schmid, dk5ras wrote:
> > Any ideas how I could change the ports used by OpenBTS? My B210 is
> > damaged on one transceiver at the moment, so I would like to change to
> > the second pair of antenna ports, means, from A:A to A:B.
> 
> Try this. It's B210 specific - we'll need more control-configure-device
code for
> a general device solution. But it will get you up and running again.
> 
>   -TT
> 
> diff --git a/Transceiver52M/UHDDevice.cpp
> b/Transceiver52M/UHDDevice.cpp index f24a5f3..1b82621 100644
> --- a/Transceiver52M/UHDDevice.cpp
> +++ b/Transceiver52M/UHDDevice.cpp
> @@ -553,6 +553,10 @@ int uhd_device::open(const std::string &args, bool
> extref)
>         if (!parse_dev_type())
>                 return -1;
> 
> +       uhd::usrp::subdev_spec_t subdev_spec("A:B");
> +       usrp_dev->set_tx_subdev_spec(subdev_spec);
> +       usrp_dev->set_rx_subdev_spec(subdev_spec);
> +
>         if (extref)
>                 set_ref_clk(true);