Custom calypso board

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Harald Welte laforge at
Sat Aug 18 09:42:01 UTC 2012

Hi RM,

thansk for your feedback.

On Sat, Aug 18, 2012 at 12:49:34PM +0530, R M wrote:

> I would suggest the board to have a connector that sends the  I Q
> signals from say openbts directly to the dsp so that there wiil not be
> a  need a usrp or any other rf board/singal generator to send the
> signal through the SMA connector.

I'm not quite sure if I'm following you.  OpenBTS is software, which
runs on e.g. a PC.  You want to get I/Q samples from the OpenBTS
transceiver program to the DSP.  What kind of "connector" do you
suggest?   The DSP doesn't have any interface that you could attach
directly to a PC.

Also, OpenBTS 'transceiver' itself implements more or less the same
functionality as the DSP in the Calypso.  So why would you want to
interface the two?  You want to run the Calypso board as a phone, and
OpenBTS as the GSM network and interface them directly using digital
baseband samples?  Then you would have one phone attached to one BTS,
not a very exciting setup for testing :/

I would presume as opposed to your suggestion, it would make more sense
to interface the ABB chip with the OpenBTS transceiver, _bypassing_ the
DSP.  This way, you could run the Calypso board as an inexpensive
transceiver, using its ABB + RF Frontend as a cheap radio.

> I would also suggest that DSP code be modified and not placed in DSP
> ROM. This would help in writing our own dsp code and make the software
> totally opensource.

lol.  And how exactly do you suggest to achieve that?  As the name
implies, it is _read only memory_.  How should we change the contents of
a mask rom on a chip that was manufactured years ago in a TI fab? ;)


- Harald Welte <laforge at> 
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)

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