Share a frequency changing pattern based off of time vs. packet received?
On Fri, Jun 27, 2008 at 9:09 AM, Ruoshui Liu <[EMAIL PROTECTED]> wrote:
> Dear all,
>
> I have been stuck with a synchronisation problem for a long time. Here
> is my problem: I am implementing frequency hopping on both Tx and Rx
> ends. At the Tx end, Tx starts changing its transmission frequency from
> channel 11 to channel 26 after the its first packet is sent and then
> keeps sending all the time. At the Rx end, Rx is probably switched on
> later on at the different time. We need the Rx to listen to the incoming
> packets and then lock itself to the transmission frequency of the Tx by
> hopping its receiving frequency.
>
> Currently, the Tx frequency is changed every 1 second with transmission
> interval of 0.25 s, and the Rx frequency is changed every 1 second
> immediately after it receives first packet. Somehow, I can't have the Rx
> has the exactly same frequency change rate as the Tx since some packets
> have been lost. The program on the Tx is written based on the
> **CountDual* *and that running on Rx is written based on the
> **TOSBase*B*, and I am using TinyOS 1.1.15.
> *
> *The core code is listed below for *TOSBase:
>
> *event TOS_MsgPtr RadioReceive.receive(TOS_MsgPtr Msg) {
>
> dbg(DBG_USR1, "TOSBase received radio packet.\n");
>
> if ((!Msg->crc) || (Msg->group != TOS_AM_GROUP))
> return Msg;
>
> /*
> * The frequency is changed at predefined
> * time interval.
> *
> */
> if(( (Msg->data[0]) == 4 ) &&
> enableStart){ // The loop for changing
> frequency will not start until the Rx receives some specific packets.
> freq_int++;
> call CC2420Control.TunePreset(freq_channel[freq_int]);
> // set the Rx frequency to channel 12.
> if(enableChange){
> call Timer1.start(TIMER_REPEAT, period_Timer1);
> enableChange = FALSE;
> }
> enableStart = FALSE;
> }
>
> ...
> }
>
> The reason why I manually set the Rx frequency to channel 12 is because
> I don't know how to keep the Rx synchronised with the Tx in the very
> beginning. The Rx quite easily lose the synchronisation with the Tx, but
> I really dont know any reasons for this. Could any one give me some
> hints please?
>
> Thank you!
>
> Shui
> _______________________________________________
> Tinyos-help mailing list
> [email protected]
> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>
_______________________________________________
Tinyos-help mailing list
[email protected]
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
