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Author Topic: XBee 1mW range  (Read 1006 times)
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I just did a quick outdoor loopback test of two XBee series 1 1mW wire antenna at about 3.5 feet (1m) high.
I managed over 150ft with 92% good packets which is fairly impressive. Especially since one of the XBees was running on two AA batteries
at only 2.7v.
I think this is better then the promised spec and surprising how well it works.
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Similar results here, although I haven't tried batteries, just mains power. Using the wire antenna, anywhere in the house is fine. I can put one in my shed out back (100 ft or so) and it seems to work fine too, I should check the RSS on it.

Chip antennas will definitely not go as far in the house, haven't tried them outside but I can find locations that aren't reliable. Also have a couple with the RPSMA connector, but haven't done much with them.
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Washington
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Similar results here, although I haven't tried batteries, just mains power. Using the wire antenna, anywhere in the house is fine. I can put one in my shed out back (100 ft or so) and it seems to work fine too, I should check the RSS on it.

Chip antennas will definitely not go as far in the house, haven't tried them outside but I can find locations that aren't reliable. Also have a couple with the RPSMA connector, but haven't done much with them.
Haven't tried chip antennas. I bought the wire antennas because I wanted good range but still keep the power consumption low so the higher power versions were not an option.
Current draw is about 50Ma regardless if its transmitting or not.
It also has decent coverage of the house. Signal is alittle weak on one side of the house because of a metal wall.
I was concerned that the range measurements were optimistic but it does that and more with ease
The signal is about -70 at 150feet. A bit above the threshold of receive-ability.
 
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I have an application that transmits data once per minute, and I chart the RSSI. I've seen it occasionally as low as -90dBm, maybe even a couple less. Interesting that during the night when the house is quiet (electrically as well as otherwise), signal strength is stronger and very consistent. When I'm in my office where the one node is, with two or three PCs running, and lots of fluorescent lights with electronic ballasts, things bounce around much more.

The other interesting thing (I'm using S2 XBees) is adding a third node physically somewhere between the other two. This will sometimes cause an increase in signal strength because the traffic will sometimes switch to be routed through the intermediate node. So that's one way that the mesh networking can be seen doing its thing smiley-grin The RSSI for the intermediate and the furthest nodes will then be nearly identical -- RSSI only reports the last hop.


* rssi.png (19.07 KB, 558x240 - viewed 11 times.)
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I have an application that transmits data once per minute, and I chart the RSSI. I've seen it occasionally as low as -90dBm, maybe even a couple less.
It seems to work down to -90db but the packets are only about 20-30%.
Quote
Interesting that during the night when the house is quiet (electrically as well as otherwise), signal strength is stronger and very consistent. When I'm in my office where the one node is, with two or three PCs running, and lots of fluorescent lights with electronic ballasts, things bounce around much more.
When I get it near the computers and other rf noisy devices, the measurement does indeed drop. It seems to be a measure of usable signal not raw signal strength.
Quote
The other interesting thing (I'm using S2 XBees) is adding a third node physically somewhere between the other two. This will sometimes cause an increase in signal strength because the traffic will sometimes switch to be routed through the intermediate node. So that's one way that the mesh networking can be seen doing its thing smiley-grin The RSSI for the intermediate and the furthest nodes will then be nearly identical -- RSSI only reports the last hop.
That could be useful for range extension. I am new to working with XBees and working with Series 1 since they are alittle easier to work with for newbies.
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I've got the higher powered ones series 1.  Nearly a mile outside, half mile thru trees, with tiny rubber antenna.  Measuring packet retries after changing the max retry parameter to a higher number is a better indicator than RSSI.  Even when 100% get thru, you can measure the % retries before they are successful.  It was difficult for me to figure out, but now it is easy to put them to sleep even for a short period of time to save power using a hardware pin between packets.
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I've got the higher powered ones series 1.  Nearly a mile outside, half mile thru trees, with tiny rubber antenna.  Measuring packet retries after changing the max retry parameter to a higher number is a better indicator than RSSI.  Even when 100% get thru, you can measure the % retries before they are successful.  It was difficult for me to figure out, but now it is easy to put them to sleep even for a short period of time to save power using a hardware pin between packets.
What do you have your packet retries set at?
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I tried the highest value, I don't recall what it is.  But that is not much better as an indicator than 3.  Look at the change in total retries.
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I tried the highest value, I don't recall what it is.  But that is not much better as an indicator than 3.  Look at the change in total retries.
But does the data come back more intact at larger distances?
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Yes, it comes perfectly if you let it retry before continuing the next packet.  I used a hardware pin to detect when it is OK to continue sending at the highest possible baud rate.
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