If you have F2, in decimal is 242. To this value you have to substract 256
(to get a signed value) and then use the formula of CC2420:
CC2420 Rx sensitivity = RSSI + RSSI_OFFSET where RSSI_OFFSET = -45dBm
Then you'll have the value of -59 dBm.
Regards,
S.
2006/4/17, #AMIT SATPATHY# <[EMAIL PROTECTED]>:
Hi.
I have managed to rectify my error from below. I forgot to increase my MSG
LEN for my TOS Msg. Thats why i couldn't copy the Msg->strength into the my
msg packet.
However, now i'm confused. The CC2420 datasheet says that the RSSI value
is an 8 bit, signed 2's complement in the RSSI.RSSI_VAL register. However,
the value i get to see is in hexadecimal format(i.e. for example, it
appears as F2). So do i have to assume that the value is actually negative
at all times or can it be positive also? After conversion to the decimal
form, is the value in dBm?
Thank you and regards.
Amit.
------------------------------
*From:* [EMAIL PROTECTED] on behalf of #AMIT
SATPATHY#
*Sent:* Mon 4/17/2006 11:56 AM
*To:* [email protected]
*Subject:* RE: [Tinyos-help] How to begin for RSSI for motes?
Hi. I have tried modifying TOSBase as suggested to include the RSSI
value but when i use Listen to view the incoming packets, i don't see the
RSSI value anywhere. For example, the packet i see is as follows:
FF FF 00 DD 14 84 01 01 00 92 01 EE 01 CC
03 00 00 0D 02 E5 01 2D 01 BD 00
I'm using a MTS310 sensor board. So all the data values that i see are
actually values of data of the sensors. The RSSI value is supposed to come
at the end of my data(i.e. just after the BD 00 part). But it doesn't
appear. When i use MATLAB to see the actual packet that is being sent, i get
the following:
7E 42 FF FF 00 DD 14 84 01 01 00 92 01 EE
01 CC 03 00 00 0D 02 E5 01 2D 01 BD 00 F2 85 7E
What does the first 2 bytes and the last 3 bytes actually represent? Is
the RSSI value actually anywhere in there?
I have actually modified the part of the code in TOSBase as follows:
-----------------------------------------------------------------------------------------------
event TOS_MsgPtr RadioReceive.receive(TOS_MsgPtr Msg) {
TOS_MsgPtr pBuf;
dbg(DBG_USR1, "TOSBase received radio packet.\n");
if (Msg->crc) {
/* Filter out messages by group id */
if (Msg->group != TOS_AM_GROUP)
return Msg;
atomic {
pBuf = gRxBufPoolTbl[gRxHeadIndex];
if (pBuf->length == 0) {
gRxBufPoolTbl[gRxHeadIndex] = Msg;
gRxBufPoolTbl[gRxHeadIndex]->data[20] = Msg->strength; *//ADDED IN
* gRxHeadIndex++; gRxHeadIndex %= QUEUE_SIZE;
}
else {
pBuf = NULL;
}
}
if (pBuf) {
post RadioRcvdTask();
}
else {
pBuf = Msg;
}
}
else {
pBuf = Msg;
}
return pBuf;
}
------------------------------------------------------------------------------------
Is there anything actually wrong with my modification?
Thank you and regards.
Amit.
------------------------------
*From:* Sara B. [mailto:[EMAIL PROTECTED]
*Sent:* Thu 4/13/2006 10:07 PM
*To:* #AMIT SATPATHY#
*Subject:* Re: [Tinyos-help] How to begin for RSSI for motes?
Yes, for example:
Msg.>data[0] = Msg->strenght;
Regards,
Sara.
2006/4/11, #AMIT SATPATHY# <[EMAIL PROTECTED]>:
So in this case, i just need to add a few lines of code into my TOSBase
program for the base node?
Thanks and regards.
Amit.
------------------------------
*From:* [EMAIL PROTECTED] on behalf of
[EMAIL PROTECTED]
*Sent:* Mon 4/10/2006 12:34 PM
*To:* [email protected]
*Subject:* RE: [Tinyos-help] How to begin for RSSI for motes?
Amit,
what you want to do is program the mote such that it will send the
signal strength value in the payload of the packet (TOS_Msg.data).
Then you'll be able to see it on PC.
Hope that helps,
Demijan
Quoting #AMIT SATPATHY# <[EMAIL PROTECTED]>:
Hi.
I read the AM.h file and i saw the Msg-> strength field. However, i
also
noticed that its only an internal value. Something that cannot be seen
in the
message packet sent to the PC. How do we extract this value from the
radio to
display on the PC? I have read the CC2420 datasheet but at the moment,
i
still cannot find any relevant material.
Also, is this value sent from the original mote that is sending the
packet or
is it something that the base mote computes? Because if its something
that
the mote sends to the base mote, then it would be pretty useless.
Thanks and regards.
Amit.
________________________________
From: Sara B. [mailto:[EMAIL PROTECTED] <[EMAIL PROTECTED]>]
Sent: Fri 4/7/2006 2:23 AM
To: #AMIT SATPATHY#
Subject: Re: [Tinyos-help] How to begin for RSSI for motes?
Hi,
You can read RSSI value from TOS packets. Take a look to AM packet
format
(AM.h) and you0ll see Msg->strength, that is RSSI value. For more
information, you can read CC2420's data sheet.
Regards,
Sara.
2006/4/6, #AMIT SATPATHY# < [EMAIL PROTECTED]>:
Hi!
I am currently trying to learn up on RSSI for motes. But i have
no idea
where to begin from. I have tried looking through the apps folder in
tinyos
but i can't seem to find a program that uses RSSI. Could someone point
me to
a website or an application which starts off RSSI for beginners?
Thank you and regards.
Amit.
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