My oft referenced radio tests indicate something on the order of
100 (default TOS_Msg's) per second as the maximum rate for micaz,
and presumably telos/tmote. And a Q&D eyeball test of the tmote
USB connection showed about 200 msg/sec if I remember correctly.
So you should be in the right ballpark at 20ms/msg. The 250kBps
radio spec is only an ideal due to the MAC protocols.

My tests were done with T1 and TOSBase so maybe there is something
different about Basestation. I would first try ramping up the send
rate to see if there is a bottleneck point. And have a look at the
radiosendtask() to see if it is blocking unnecessarily.

MS

Bhavish Aggarwal wrote:
Hi,

I'm sending AM packets to a mote from a PC via USB at a rate of 20 ms
with data payload = 33 bytes. I've disabled the ack mechanism in the
PC to mote USB transfer. But only a fraction of the packets I send
reach the mote (I am incrementing a counter in the UartReceive.receive
event). On the other hand, if I comment out the "post
radiosendtask()", all packets I send from the PC reach the mote.

Is the radio send api call taking more than 20 ms to send out 33 bytes
of data? A simple back-of-envelope calculation using the data rate of
250kbits/sec over the radio shows that a packet of 33 bytes should
take 1 ms to send out.

I'd really appreciate any help on this issue.

Thanks,

Bhavish
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--
Platform: WinXP/Cygwin
TinyOS version: 1.x, Boomerang
Programmer: MIB510
Device(s): Mica2, MicaZ, Tmote
Sensor board: homebrew

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