. Peng,
here, in Brazil, we use to say "the hole is deeper" (o buraco eh mais embaixo). You have to read and understand the programs of radio control. The radio communications use CSMA protocol. If a node wants to send message, it turns on the radio in RX mode and "hear" the channel. It measures RSS and informs as RSSI. If there aren't any other radio sending message, your radio "hears" only noisy, indicating that the channel is clear. If other radio is transmiting, your radio senses a more powerfull signal, indicated by RSSI, and it understand that the channel is occuped. If the channel is occuped, your radio returns to idle mode, and try to transmit later. If the channel is clear, then your radio changes to TX mode and sends its message. Thats the reason you only gets the noisy reading only just beffore a transmission. Then you have to read the code, understand it, and modify it to read noisy intessity at a time you wants. Maybe, you make a new function in RF230layerP. In this function, you take the procedures to transmit message, but you stops the procedure when the radio is going to changes mode to TX. If the radio will change to TX, it is because the channel is clear, and RX "heard" only noise. Then you've get noise RSSI. Just put one more flag in that function. It is not an easy task. Here in Brazil, we would say "you are brushing bits" :-) ***************** João Giacomin Prof-DCC-UFLA ***************** ---------- Original Message ----------- From: Peng <[EMAIL PROTECTED]> To: [email protected] Sent: Mon, 10 Nov 2008 00:21:19 -0500 Subject: [Tinyos-help] RF230 Noise measure. > Hi, there, > > I'm modifying the RF230layerP to realize function same as RSSIsample to > measure the environment noise. > Last time I got some advise like: > > 1) The RF230LayerP.nc already measures the RSSI values both for busy > channel and clear channel. You can implement a new interface that > return the rssiClear and rssiBusy values. > > but when I read RF230layerP I found that these two values only calculated > when there message is about to be transmitted, So it is not possible to > measure environment noise using this value. So is there some better way? > > The other question is about the tasklet_async and Tasklet interface, I do not > understand its function, someone can explain it to me? > > sincerely > Peng ------- End of Original Message -------
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