Re: [Discuss-gnuradio] OQPSK for IEEE 802.15.4

[Thomas Schmid]

Hi Luis,

I implemented exactly that. Here is the code:

http://acert.ir.bbn.com/projects/gr-ucla/

Thomas

On 7/21/06, Luis Simoes <address@hidden> wrote:
> Hi all,
>
> I will implement a ZigBee transceiver on Gnuradio using channels in the 2.4GHz
> ISM band. I studied a bit the IEEE standart and I could observe that ZigBee
> uses DSSS channel encoding with 32 chips long random noise sequences and an
> offset QPSK modulation scheme. The offset between In-phase and quadrature
> streams is a half symbol duration. Does anybody have an idea how to build a
> phase detector and decision device for this modulation in Gnuradio? What's
> about the costas loop for QPSK detection? Is this loop able to trigger the
> offset fast enough or should I build two phase detection loops, one for each
> stream (I & Q). After having the two streams what could be the best way to
> achieve symbol recovery? And , as last question for the moment, in
> transmission mode how can I build a delay for the offset needed? DSSS is not
> a big deal and I think that I will write a block with simple mapping tables.
>
> I am still designing the application and some tips would be very precious to
> start implementation by the right way.
> I appreciate any advise or tip and I'd like to thank all of you in advance.
>
> Luis
>
>
>
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