Re: [Discuss-gnuradio] Some new 802.15.4 stuff

[Bastian Bloessl]

Hello Dingwen,

On 04/22/2013 10:13 AM, Dingwen Yuan wrote:
> I think the loopback works. I get some logs in the gnuradio-companion
> likes this:
> Hello World!
> ut

I casted the not-0-terminated buffer to char as debug output :)
Should be fixed now.

> Changing gain and the direction of antenna really improves the packet
> reception rate. I have just one USRP, therefore I tried the
> communication between USRP and your contiki code.
> The log I got always look like a number of Os folowing by Hello Gun
> Radio, like OOOOOOOOOHello Gnu Radio. What does the O means?

OOOO means that the PC can't keep up with the sampling rate and thus, 
experiences 'O'verruns. That was because I set the sampling rate way 
higher then needed. I just pushed the flow graphs with a rate of 4Msps.

You can play around with that, you just have to set the 'Omega' of the 
'Clock Recovery MM' block accordingly (samp_rate / Omega != 2Msps).

>     Just out of curiosity, did you try the transceiver? Is it working
>     for you?
>
> I tried transceiver, it doesn't work. But tx works perfectly.

Maybe because you are using a full-duplex daughterboard while I use a 
half-duplex one. Would be great if you try to set the antenna of the 
USRP source and sink blocks manually to the same value. Then it should 
operate in half-duplex mode. (I think this is possible with your board, 
check 'uhd_usrp_probe' to see a list of options)

> BTW, what have you changed in your code in comparison with the original
> UCLA Zigbee.
The receiver structure, the parameters of the flow graph (clock 
recovery...), and the 'packet_sink' block is from the UCLA 
implementation. This is where all decoding happens.
It is based on this implementation, so you can see the changes in git.

I just pushed the changes to github.

Hope it helps!
Bastian