Re: [Discuss-gnuradio] RAW source

[Activecat]

Sara,

We don't seem to communicate at the same frequency.

I have nothing else to say.

Good luck.

On Wed, Jun 25, 2014 at 11:06 AM, Sara Chérif <address@hidden> wrote:

Thanks Activecat very much .

Now, SIP packets length is varying & RTP packets have fixed length of 87 bytes . Now to input this traffic coming from the soft phone to the Gnuradio to be processed, i use the UDP source block(to read the UDP packets from the soft phone port)
  in UDP source block , I can determine only one port number and Ip address. I put the IP address of the Wlan interface (my laptop IP address) , i also tried to put "0.0.0.0" and the port number of twinkle soft phone on which i receive the RTP traffic.

I faced some problems:

First ,How to receive now the SIP signaling packets and the Rtp packets at the same time to establish a call with another soft phone ( as the soft phone uses 2 different port numbers for sip & RTP while i have to identify only one port number in the UDP source block)??
The flow graph i use consists of :Udp source - throttle -Uchar to float and WX GUI sink scope.
I tried to duplicate the flow graph (to use another one which is the same as above and runs in parallel )
Also I tried to use 2 UDP source block then the add block.
But I don't know till now how to multiplexes the two traffics (SIP and RTP) as we need to integrate the whole system to see this & what is the right method ? DO I have to write simply the port of the ethernet connection ?
What will I do in this case  : If I want to make the call between the 1st & 2nd lap ( One has Twinkle & the other has GNU Radio & Twinkle,  and I want GNU Radio to capture packets coming to Twinkle ? (use 2 udp source + add block ) ?

Second, i don't know how to determine the payload size. what if the packet length in the case of the Sip signaling is variant. In the  soft phone, we can determine the maximum transfer unit (MTU), does this help here ?

Third, i have a question relating to the OFDM transmitter: what is the required packet length , I wrote it 100  as each sip packet is 87 bytes and I will use coding with rate 7/8 then after coding each packet is 100 bytes) what if the packet length is variable as in the case i stated above (SIP pkt length is not constant)?

Note: i want to capture the packets coming from the soft phone in order to process them on gnuradio using OFDM system and send and receive them at the other end using two Usrps to be used as input to the other soft phone.

Thanks in advance