Re: [Discuss-gnuradio] embed fix sequence in payload part

[Tom Rondeau]

pratik hetamsaria wrote:
> hi..
>
> i am trying to embed a fixed sequence which i want to recover during 
> demodulation. I have read from the previous archives that it would be 
> easier to embed it in the payload part.However, as soon as i add 
> anything in the payload part, and try to receive using rx_voice, i get 
> an error saying
>
> terminate called after throwing an instance of 'std::runtime_error'
>   what():  msg length is not a multiple of d_itemsize
> Aborted (core dumped)
>
> What I have understood is that the msg length changes as soon as I add 
> something to the payload.If I dont do anything and just run 
> rx_voice.py then the msg length comes to be 1687/1720
>
> I have tried getting the msg length after adding different sequences.
> If i change the code as:
> payload = payload + preamble, the msg length changes to 1719
>
> Otherwise, If i change as:
> payload = payload + default_access_code
> the msg length changes to 1751
>
> where default_access_code and preamble are given in packet_utils.py.
>
> I have not been able to find out the value of d_itemsize or what 
> should be its value so that the code runs.
>
> I would be very grateful for any help.
>
> Thanking you,
> Pratik Hetamsaria

Pratik,

I'm not entirely sure what you're trying to do. Which example code are 
you using? And also, what's the purpose of what you are trying to do? 
That might help us set you in the right direction.

Please list the code where you are making the change to add your fixed 
sequence.

Tom