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Author Topic: Filter RF noise  (Read 601 times)

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Offline damanfbTopic starter

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Filter RF noise
« on: December 01, 2010, 04:14:44 PM »
Hello,

I am using a RF transmitter/receiver pair for a mechatronics project and I am having some trouble.

 The module can be found here: http://www.robotshop.com/sfe-rf-link-4800bps-receiver-434mhz-3.html
                                            http://www.robotshop.com/sfe-rf-link-transmitter-434mhz-3.html

I have them somewhat working.  They are communicating and sending mostly correct data byte.  The few bytes that are corrupted by noise however are causing large problems with my project.  I am building a mobile robot, controlled over RF with a Playstation2  controller.  I have the controller working, and have tested my code with a wired connection and am now making it wireless. 

Does anyone have any suggestions on noise suppression or some way to get the data send with fewer/no errors?

Offline waltr

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Re: Filter RF noise
« Reply #1 on: December 01, 2010, 05:23:23 PM »
Is the interference worst when the Bot motors are running? If so then some suppression on the motors should help.

You also could send redundant data and/or include a method of error checking the data like a CheckSum.
Since you have these RF modules working fairly well I'll guess you are using a Manchester or similar encoding of the data. If not then this may also help the RF link reliability.

Search these forums for discussions and solutions about the above topics.
Here is a current thread on just the trouble you are having:
http://www.societyofrobots.com/robotforum/index.php?topic=2135.0
« Last Edit: December 01, 2010, 05:25:26 PM by waltr »

Offline macdad-

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Re: Filter RF noise
« Reply #2 on: December 01, 2010, 09:26:48 PM »
Make sure any loose, long wires going every which way, are not near the Transmitter/Receiver pair as cross-talk would become an issue. Also be sure that the Transmitter/Receiver pair are not near any Electromagnetic sources, e.g. Motors, solenoids, other oscillators, crystals, etc.

Be sure to have the RF circuits being feed a regulated supply, voltage spikes, and voltage drops tend to mess with oscillators and their related circuitry. Another thing, add a ceramic capacitor of about 0.1uF and an electrolytic capacitor of about 10uF to the power supply rails of the RF circuits, this will filter out other spikes and help "smooth" the supply voltage.

You might also want to find some RF shielding for those units, as they look pretty exposed, but I recommend that you do the above advice before creating some RF shielding.

 


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