On Jan 15, 2008, at 4:25 AM, Ruoshui Liu wrote:
Dear all,
I am trying to measure the RSSI value in TinyOS 1.x. However, I
have got two totally different values when I applied two methods to
do this, one is to read the 'strengh field' in the TOSMsg as the
MPR/MIB manual suggests, and the other one is to read the RSSI_VAL
register. I am wondering why I have obtained such different values,
for example,
before adding the offset value (-45): the reading from the
'strengh field' is -20; the reading from the RSSI_VAL register is -53;
after adding the offset value (-45): the reading from the 'strengh
field' is - 65; the reading from the RSSI_VAL register is -98.
I am really confused, could anyone help me with the reason for this
pleaes?
The strength field is the RSSI of a received packet. If you read the
RSSI register, then you might be sampling the RSSI when you are *not*
receiving a packet, at which point it is the hardware noise floor.
-98 dBm is a reasonable hardware noise floor for a cc2420-based node.
Phil
_______________________________________________
Tinyos-help mailing list
[email protected]
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
