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Author Topic: noise resistant wireless comm  (Read 864 times)
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So I have a robot, large w/ big angry (theoretical 110 amp stall) motors, so I assume all 4 of those running together can make a whole lotta noise.  For debugging and testing purposes I need to get some data from the robot, and simply sitting a laptop on top of it has worked, but has some serious short comings.  Anyways I am looking to go wireless, and want to know what you would think would be the most likely not to see interference.  I have a Mega on teh bot with a serial port still free, so an additional module would be preferable, although I also have a an arduino Ethernet and could couple it w/ a router, but that sounds like much more complication than I desire. 

I am not really sure I need two way comm, but I figure I might as well go all out.  I want something simple, can hook to my MEGA, and will not get all messed up being a foot from such big motors.  I don't need to konw how to use it, I can figure that out myself, but I do need to narrow down my options, there is a LOT out there to choose from.

I am really glad I finally got RXTX beat into submission so I can visualize my data w/ processing, but its hard to chase my robot up and down a field staring at a shaking screen.
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oh range, I guess 10 yards would be minimum.
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So I have a robot, large w/ big angry (theoretical 110 amp stall) motors, so I assume all 4 of those running together can make a whole lotta noise.
First step is to minimize that noise, with caps. What steps have you taken to do that?

If nothing, see Grumpy_Mike's page on motors.

Range, amount of data to send, critical-ness of that data, etc. are all factors to consider.
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While you must take all the precautions not to generate noise in the first place, the other thing that can help is a robust error correcting protocol. It will not recover data from a total wipe out but can correct the odd corrupted byte. You should transmit your data in packages with a header, data and check sum of some sort. You must at least detect any error in a package and not use the data if it is corrupt.
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I don't have noise issues, I just expect to.  Currently I am using a DSM2 remote for controlls and have 0 noise issues, never loose signal, no weirdness, etc.  I just want to know what purchase will put me in the best position to combat noise.  IE what flavour of wireless would be best for a data collection/feedback system.  This way I can throw bad money after good, instead of hte other way around.  Right now I only have a very small handfull of peices of data I desire to send back.  System  volatage, 4 current and speed readings, as well as 4 command states, and that is it.  In the not too distant future I expect to play with video, but then I will simply move over to WIFI for my communication needs.

As for combating noise, I have read Grumpy mikes stuff, that entire site is fantastic, perfect balance of technical and clear to read.  Still reading through everything in detail, got plenty of questions, but I plan on saving those for later.  as for caps in inductors to shush up a motor, how important is it that they be mounted close to the motor?  my motors have leads no terminals, so I need to cut my wires to put them right up against the source of the problem, and don't like cutting heavy leads unless I have to.  I have a quality crimper, but I don't like making more connections than needed, and water-resistance is important in my build.
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as for caps in inductors to shush up a motor, how important is it that they be mounted close to the motor?
The closer, the better. The caps stop noise from getting away from the motor. The farther away, the more noise.

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my motors have leads no terminals, so I need to cut my wires to put them right up against the source of the problem, and don't like cutting heavy leads unless I have to.
Pictures would be nice.
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they would but my phone has been throwing a temper tantrum last few days.  Replace one screen with an off brand one and the wee lass acts like I bought her tickets to an Nsync concert instead of One Direction.  Dramatic little thing. 

They are 4 NPC T64s, which I understand are super common motors.  A bit faster than I need so I am running them at 12 volts, but the built in gear box/bearing system makes them worth every penny.  I had a strong suspicion that the wire leads were basicly antennas so putting the caps at the motor is key, just wanted to verify.
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