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Re: [Discuss-gnuradio] DECT anyone?

From: Alexander List
Subject: Re: [Discuss-gnuradio] DECT anyone?
Date: Sun, 02 Dec 2007 21:04:05 +0100
User-agent: Thunderbird (X11/20071022)

Sorry for the long delay replying...

Eric Blossom wrote:
> If you're serious about this as a project for your master's thesis
> and you're willing to contribute the code to the project, we can
> probably find some way to get you a daugtherboard.  Will the
> university pay for the daughterboard?

Will try to convince them. Otherwise I'll sell my car ;-)

Johnathan Corgan wrote:
> I had started a receiver module in examples/python/dect, but didn't get
> very far.  What's there will tune to a supplied frequency, apply the
> appropriate channel filter, demodulate the GMSK to (unpacked) bits, then
> record to a file.  I was able to "grep" the bits for DECT
> pre-amble/synchronization codes and see them.

Well, at least a starting point...

> This was to be a "service monitor" type of application, not a base
> station or handset.  So none of the TDMA aspects were considered.  We
> still need (ahem) mblocks and in-band signaling to properly implement
> either end of the protocol.

Is there an ETA for the mblocks? I'm not that much in a hurry, I won't
be able to start my thesis before next summer anyway. And I'll be happy
to discuss something like a roadmap with you folks before proposing this
project to a supervisor over here. No idea if it's too big for a MSc
thesis ...

> A base station stack that could handle a single DECT TDMA carrier would
> be able to support 12 cordless phones full-duplex.  Wrap it up in an
> Asterisk channel driver and you have a small office cordless PBX for the
> price of a USRP and PC, using entirely Open Source software.

Yep, true, that's interesting from the political POV, but that's a
rather expensive solution to get a SOHO cordless PBX... However, as a
proof of concept it's worth the investment. And most likely cheaper than
an "old school" enterprise PBX with the DECT features enabled and DECT
base stations attached...

> The DECT protocols are very well documented, and the handsets are very
> cheap...

That's true. You even get SIP capable base stations over here in Europe
for ~EUR 70-100 (USD 100-150) that allow you to assign different VoIP
providers to different handsets, use IM on the handsets, ... but of
course without source ;-).

I wonder what other means to aid development are out there. I guess some
kind of DECT monitor and/or base station with debugging capabilities
would be really nice. If we do DECT in free software, we should be able
to prove it's ETSI compliant ;-)


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