Mohammad,
Yes, I believe the problem is with the actual connector that is MMCX
adapter soldered to the board, i've had problems with them coming
completely off the board and taking the PCB lines with them. I would
first try re-soldering that piece first. If this doesn't work, then an
alternative solution would be to use the through-hole connectors for the
antenna. It should be located near the MMCX connector.
Using the through-hole connectors may be a little bit tricky since the
antennas have an MMCX connector attached to the end. You may want to
try making a very simple dipole(you won't get as good of a performance
as the actual antenna because of impedance mis-matching) using a wire of
the appropriate length, or you can use one of the female MMCX connectors
to interface with the through-hole connector and the existing antenna.
Let me know what happens,
-Paul
On 12/22/2009 10:23 PM, Mohammad S. Hashemian wrote:
Thanks Paul, you're right, most likely the problem is with the
antenna. But the point is that as you know for Micaz, the antenna is a
2.4 ghz pcb antenna! how can I re-solder it? by now I've cut the
antenna of one of the motes totally and re-soldered it, but it didn't
work and also I resolder another mote (without cutting the antenna
first, just by adding more solder to it board), but it didn't work
either! any suggestions how can I do it?
And also do you think if the problem is with the connection between
MMCX female part and board or the female part itself is damaged? (the
antenna should be fine, I tested it by changing a new mote's antenna
with a damaged one, and it still was working fine)!
thanks again for your help,
Mohammad
2009/12/22 Paul Johnson <[email protected] <mailto:[email protected]>>
Mohammad,
One thing you may want to check out is the antenna connection to
the micaz board. The board-mounted connector can be pretty
fragile and can be easily broken off if the antenna catches on
anything, or you attempt to remove the antenna by pulling at an
angle. What I would do is try to re-solder the antenna one one of
the boards that are malfunctioning and see what happens.
10cm is about the range I've seen micaz/mica2 nodes work w/out an
antenna connected at all, so the antenna is likely the cause of
this problem.
Hopefully re-soldering the connections fixes this and you don't
have to buy new boards,
-Paul
On 12/22/2009 4:53 PM, Mohammad S. Hashemian wrote:
Hi All
We have run a project using micaz modules. In this project there
are 8 nodes which are fixed in a certain locations and 40 nodes
which are carried by different people (some of these motes are in
XBow boxes and some other are just in small pouches). There are 3
motes which are used as base stations through the environment.
The problem we have now is that the transmitter of the mobile
motes gets damaged after a while. For example we pick a new mote
out of the pack, program it, and give it to one of the people,
after a while (sometimes even after 3 days!!!) the transmitter
(either sender or receiver) stops working.
I realize the transmitter of a mote has stopped working when I
don't receive any signal from it for a couple of days. In this
case I test the mote with CountSend and CountReceive (shipped
with XBow MoteWorks) against another new mote. Usually the result
is that either the sender part or receiver part of the mote has
become so weak that the packet can be transferred only if the
motes are less than 10 cm away!!! further than that the packet
either can not be sent or be received. I've called the company
regarding this issue and they told me if the mote doesn't work
with CountSend and CountReceive, you should send them back here
for diagnosis and because by now they are out of warranty, it
costs 100$ per each for diagnosis (The motes have been bought
more than a year ago, but they haven't been used at all).
On possibility was that the motes that we got have been produced
using a bad batch in the manufacture for transmitter, and that's
why they keep dying in work. But it's not very likely because the
problem is just exist with the mobile ones, not with the base
stations or with the fixed motes. Also the currently used motes
have been purchased in two separate orders, and probably two
separate manufacturing series.
The other possibility is that they die because of the static
electricity (people are supposed to change the mote's battery
every couple of days). Can it be a reason? But this even happens
for the mobile motes with XBow boxes which they look safe for
this. and if it's the reason, why just the transmitter gets
damaged and no other part in the mote?
By now we have lost more than 30 micaz motes this way and if it
wants to continue we will much more. Does anyone has any idea
what can be the reason and how we can stop it? Any idea is highly
appreciated.
Thanks,
--
Mohammad S. Hashemian
Research Scholar/DISCUS Lab
Department of Computer Science
254.2 Thorvaldson Building
University of Saskatchewan
(306)966-1947
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