PWM Noise Explained (kinda)

I have been working on my TM, so I thought I would make this short video so someone might relate to what is going on with pwm as related to noise and speed of the TM.
You will see the noise spikes near the end of the video. I did some rough calculations of the noise frequencies present. The noise ranged between 1 megahertz down to 100 kilohertz. These noise frequencies fall in the band of the sonar transducer frequencies. (RF). That is why you see it on the screen. This is just a show and tell and does not cover all the noise sources of RF.

Hope it make sense to someone.

http://i188.photobucket.com/albums/z...h_PWMNoise.jpg

Good work.i havent watched the whole video yet but will when i get time.how far away from the rf source can it be detected?in relation to trolling motor to sonar

One of the best ways to find fr concentration is with an AM radio. Get one with an extendable antenna. Tune the radio receiver between stations and just get the "white noise" (sssshssshshsss sound). Now, just use the radio antenna and move it around your boat like a divining rod. When the noise is loudest, you will be near the rf source.

I have to be connected to power and ground directly to get good pictures with this scope without special adapters. What I should use is a spectrum analyzer but I ain't spending 10 grand to look at a 500 dollar TM. ha

Thanks CP , I understand more than I did LOL , Electic always amazes me .

Great video lesson Tom...

Can you also put that video in our "RF Interference" sticky....?

Rickie

Good Stuff. Nice to have an explanation.

Quote:

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Originally Posted by rnvinc

Great video lesson Tom...

Can you also put that video in our "RF Interference" sticky....?

Rickie

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Ok. I added a little more stuff to the text. Useful trivia sorta.

This is useful since I just put a transducer on the terrova and tested it with no load last night. As CP indicated in the video, no noise was shown on the sonar. I guess the real test will come when I load the terrova up.

thanks.