I work on XBee and I use the RSSI (received signal strength indicator) as a distance measure between nodes. Does the RF12B provides a command to get the RSSI of the latest received packet?
how to get RSSI or POWER signal measure on RF12B?
(15 posts) (6 voices)-
Posted 26/04/2010 10:19:33
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I'm a newbie but i was looking at the same thing as you, so maybe I have the correct info. It seems the RD12B has a digital RSSI signal that turns on if a certain RSSI threshold is crossed. This can be read from the Jeenode itself.
If you really want a value you need to get the ARSSI value from the module. This requires some soldering. For more info see this post http://news.jeelabs.org/2009/12/25/ook-reception-with-rfm12b/ At about a third in you'll find some pointers.
if anybody sees this and I'm totally wrong please correct me ;-)
Posted 26/04/2010 11:52:11 -
Yes you are right. I also found some reference on this post: http://talk.jeelabs.net/topic/66 So It's similar to the Nordic chips the digital register only gives you a binary value (in their case is even worse because you cannot set the threshold) and if you want the analog one you need to use the ARSSI. I prefer xbee in this case you can get either a PWM of the RSSI or just ask for it in API mode! I'll try the digital approach, at least I can discriminate by threshold.
Posted 27/04/2010 06:11:17 -
So i soldered a wire to the aRSSI point but I'm completely clueless about what to do next. I put them it an analog port to read out when a signal comes in but I think this is a little optimistic since it returns nothing. Can anyone has and example/ some poiners on how to read aRSSI value?
Posted 18/05/2010 11:20:50 -
The signal needs amplification to be readable as on/off signal by the ATmega, see
Bit hard to find this info, right now. It's currently filed under
Posted 18/05/2010 11:41:36 -
Here I did a test to compare the RSSI between the chip antenna and the wire antenna. There's some code that might be useful.
Posted 09/12/2010 15:14:43 -
Yes ,it would be very interesting to know which antenna performs best and how far ,maybe you can quickly put the "ping jeenode 3" outside (50-75 meter) and run back to your warm house and see the result.?
Posted 09/12/2010 18:25:43 -
Exactly, I need another human being!
Posted 10/12/2010 08:29:17 -
Oky the RSSI at -73dBm goes off at about 20 meters for the chip antenna. Weirdly enough the Jeenode USB stop working systematically, it could be due to the low temperature but the arduino mini keeps working. The temperature was about 5 degrees. So I could not compare yet unless somebody can measure the RSSI at about 20 meters in open space. I'll try again tomorrow if the sun shines.
Posted 11/12/2010 16:34:37 -
By the way, if anyone is interested in doing detailed RF power measurements, I recently came across the "SignalHound" (add .com for the website) which is a small RF spectrum analyzer covering 10 Hz - 4 GHz, USB powered, priced under US$1k. As a "software defined spectrum analyzer" it's as much software as hardware, and unfortunately requires a Windows PC to operate. However, it seems to have a huge price/performance advantage over a traditional HP/Agilent analyzer in that frequency range. I don't have one myself, but some folks were discussing it on another list, http://www.mail-archive.com/time-nuts@febo.com/msg34037.html
Posted 12/12/2010 02:15:29 -
Thanks - great tip! I wish I'd have access to something like this. It's a bit out of my budget for "just" spectrum analysis. If it were also usable as truly general-puprose software-defined radio (SDR), then that might be a different situation... my impression is that it can probably do this, but lacks the software?
It's not open source, right? (not a show stopper, just curious)
Posted 12/12/2010 12:37:20 -
According to the documentation on their website, it can demodulate AM and FM signals up to 240 kHz bandwidth, but only within the interface framework that they provide. As far as I know, it is not a completely general-purpose receiver, and it is not open source.
The QS1R "Quicksilver" receiver does seem to be such a thing, although it only goes up to 62.5 MHz. According to www.philcovington.com/QuickSilver "The firmware, software, and FPGA HDL for the QS1R Receiver is available for experimentation and writing your own custom application. You can view, change, improve, and experiment with the receiver's code."
Posted 12/12/2010 17:56:51 -
Very interesting instrument. But it doesn't solve the problem of measuring the antenna gain. :-) I think the hard solution will be to solder an SMA connector and measure the antenna resonant frequency with a sort of network analyzer. I can't believe also the jeenode stopped working sistematically with the cold temperatures. poooor me.
Posted 14/12/2010 08:20:56 -
How did you power the stopping Jeenode? You know that batteries can have strange behavior in different temperature settings ...
Posted 14/12/2010 10:56:58 -
It was usb powered from my laptop :-)
Posted 14/12/2010 18:46:59