electrical noise

i'm new to the video field.  i have now installed ten concept video systems and they all have had electrical noise varying with engine rpm.  some have more and some have less.  i have tried multiple filters but every system has had some noise still present.  the noise is present when using either the concept built-in fm signal or tapping the signal wires into a peripheral pxdx.  does anyone have some tricks of the trade? do any other systems have the same problems?

Anouther question i have concerns the pxdx.  is it normal to have a significant loss of volume when transfering signal from either an mp3 player or video system through the pxdx to the factory stereo?  are there any repairs for this problem?

i have installed many filters.  they are all manufactured by peripheral.  they reduce the noise but do not completely remove the noise. any other suggestions?

Engine noise can usually be caused by improper grounding. Try ensuring that the area the ground wire is touching the vehicle chasis properly meaning remove dirt grease and scrape off paint to ensure metal to metal contact. Also the ground wire my be at least same size or bigger than the power wire feeding it. Ensure that all grounding is properly done including that of the player, sound processors and amplifiers.

Also connecting too many ground wires to the same point can create noise. I've solved many noise problems by checking the ground wires. Try it out. U may find that there is no need for noise filters too.

i used  filters and different grounds with no change.  i finally repaired the problem by installing a capacitor on the power output off the alternator.  this tip was given to me by an aircraft mechanic.  they have alot of problems with noise on the small airplanes.  i cannot remember the size or brand of capacitor but it was made specifically for alternator applications.  after finding this out i have found many alternator capacitors made by almost every brand out there. thanks for your help.