ground loop + BNC 2120 behaving like antenna(problem)

[AnalogKid2DigitalMan]

It looks like the 1205 is a brushed motor (and draws some hefty current too). You are probably dealing with conducted electrical noise. Each time the brushes make and break a winding circuit with the commutator, then it is likely that electrical spikes are being generated and sent down the wires of your circuits.

Is it possible power the motors totally independantly from everything else?
Or else try inductors/capacitor/diodes to try to squelch the noise right at the motor terminals (no experience with that for me)

[tmdar]

hi
Yes that what I did. I took the motor out of the system I supplied voltage form other supply I have place a very big 33oUF capacitor parallel to motors and one schottky diode in series and the motor was runing in my hands in air and I increased the voltage from power supply and saw the ffects in Oscope. motor had no contact it was only air which was common.
At sensor to I place 10UFarad capacitor it has two wires both shielded and grounded it only happens once I connect NI elvis with wire otherwise not.
I will also try the twisted wires too lets see what happens
thanks

[AnalogKid2DigitalMan]

Sometimes bigger is not always better, you may want to try some small ceramic capacitors (.01 -1uF) range in parallel with the larger caps. With smaller capacitance, they can responds faster to transients. You may want to google on brushed motor noise suppression circuits, I do not have much experience there.

[tbob]

Put inductors in series with the motor power supply lines. Inductors will stop the high frequency pulses coming from the motor. Somehow I have a feeling that the problem is elsewhere. Power supplies should take care of filtering out induced noise. If you put a scope on the power supply lines, you should see just DC with very little or no spikes. Do you see no spikes on DC power lines and spikes only on signal lines? Are you sure the sonic sensors are not picking up motor noise (sound vibrations)? Have you tried acoustic insulation around the motor or the ultrasonic sensor? Put the sensor in a sound proof box and see if you still get the noise on the signal lines for the senor only. See if increasing the distance between motor and sensor lowers the spike level.