MOD-ZIGBEE PIR Range

[gilduz]

Hello everybody,
I'm new, and I just received 2 MOD-ZIGBEE PIR.
I'm planning to build a huge network of this devices to cover an outdoor field.
For this reason I need almost 50mt (possibly 100mt) of range outdoor. My first test seem to be quite bad, achieving less than 20 meters outdoor.
Is there a way to improve distances modifying parameters in demo software? Otherwise is there a way to create a mesh network to permit a device to communicate not just with the coordinator but also with the neighborhood? I think that this implementation could be an huge improvement to the system.

Thanks in advance, I really appreciate a possible solution

Gildo

[LubOlimex]

Hey Gildo,

Try mainly by software means. Lower the baudrate in code for an increase in range. If it is already lowest try to increase it a bit. Why? Because sometimes the lowest possible baudrate get easily disturbed by external signals or deteriorated by obstacles (walls, metal objects, etc). Speaking of obstacles and frequency disturbance - you can't expect max range in such an environment.

I am not 100% sure but I believe it should be possible for a device to act as a repeater (router) of the host (coordinator). Maybe there would be more info on the subject at the Microchip forums or at the MRF24J40's official page. This is a scheme of typical ZigBee network: http://i.cmpnet.com/rfdesignline/2009/03/FIGURE_01_TI.jpg. Notice there is only one coordinator and many routers between the coordinator and the end devices.

Unfortunately, in the past I have evaluated the chances to mount external antenna in our MOD-ZIGBEEs and it is not going to work.

Best regards,
Lub/OLIMEX

[raetos]

Hi Gildo,

have a look at the Microchip reference design http://ww1.microchip.com/downloads/en/DeviceDoc/70329b.pdf on page 8. It seems that on Olimex schematic L3 is inverted with L1.
Also, I have some problems when I try to connect one MOD-ZIGBEE with one MOD-ZIGBEE-UEXT, I can reach only few meters the the connection goes down.

I have already posted on this forum about this issue.

Bye .

[ZigBeeGuy]

After having a cursory look at this board, it doesn't have a power amplifier (PA) or a low noise amplifier (LN A). Given that it is battery operated, it is probably going to be a sleepy end device (SED).

This means that you each radio will not have that great of a range.  Even with an external 3dBi antenna, I expect that you will probably get 30 m line of sight (LOS).  Since the device is probably a SED then it won't participate in routing.

If you want to use a network of these devices, then you should also plan to setup a network of powered routers with a PA and maybe an LNA.  This network will be your backbone, and the PIR devices will connect to this backbone.

Cheers,
Bruce

[gilduz]

Hi all, thank you very much for your help and sorry for the delay, I just read the replies.

I did some tests with prebuilt demo software at my house in mountain. That place is REALLY noise free, no houses, no 2.4 ghz devices.
The range problem persist, and I'm able to establish a connection between two devices just at few meters of distance.

Raetos, you did a great discovery! When I will be back to my lab I will try to swap those inductances, hoping it will improve range.

Bruce, I think too that I will not be able to get more than 30 meters of range. Like you said, I should set some devices like routers, maybe using a small solar cell to keep the battery charged. I'm choosing between zig bee and miwi protocols. Actually I'm not interested in compatibility but I'm looking for the easiest protocol that permit to build the network quickly. Miwi seems simpler.

Thank you Lub, after modding the boards, I will follow your suggestion trying to solve my problems.
Ciao

Gildo