a couple weeks ago i purchased a digital video recording system. Its from archos, av120 is the model and it has a 20 gig hard drive that it records too. I am having a problem with the file being currupted when it closses them out. The file is saved but i cant view it. What i am wondering is if a certian frequency can in anyway, interfere with the harddrive.
Here is what i am doing, i am using it in our race car. the eye is ontop of the car, but the recorder is inside the car in a case. What i found out yesturday is that a MSD box (ignition box) has a frequency in it. The recorder is sitting about 12 " behind the ingition system.

One other thing, what will happen to a hard drive or other compnents that would be in this recorder if they were to get too hot? I am asking this because it gets real hot in these cars, and it doesnt help that our car is black.

Thanks in advance.... i really need some help.

nate

I would not worry about the heat as much as the vibrations. Could be that the vibrations are causing disk write errors.

Have you tested the unit outside the car? On a table where no vibrations occur and see if the same error crops up again.

krellheat, have tested the unit outside the car. It records fine. everything is the way it should be. yesturday while at the track i even did some recording outside of the car, and while i was recording i taping it with my hand, i continued to tap the unit when i closed the file. it worked fine.

Thanks

Electronics can do funny things when in a 'noisy' environment - and certainly an MSD ignition will inject a lot of noise into the signals within the recorder.... Not knowing much about your digital recorder, I can only guess that the noise which is being recorded on top of your video stream is creating a signal which, when you attempt to play it back, cannot be recognized by the player.

Is the recorder powered by batteries or by plugging into the car's 12V circuit?? A choke (filter) on the power line might help...

probably is a weird frequency coming from the ignition. I have a CB in my pickup and I tried to install it under the cd player and it would not work because of the interference. I also tried routing the coax different places and that also caused it to malfunction b/c it was too close too the tranny. Weird.

Try this next time, boaters do it all the ime: wrap the source with aluminum foil or tape to create a sheild. You could also try just wrapping the player.

Some boaters I know wrap the cables with aluminum tape to create an rf shield to minimize the rf effect on other electronics.

Just my dos centavos.

My recorder is held in a hard shell case. sourounded by foam. As for power, we are currently using its own battery source/power pack but once we get the unit working propery, we will be getting our power direct from the car through 12v.
What doesnt make sense is that it worked fine on 2 different occasions. I'll try and put the recorder in a different place the saturday and see what happens. if anyone else has any info they can give me, please let me know.
thanks

nate

Originally posted by dawg@Jun 22 2004, 11:33 AM
My recorder is held in a hard shell case. sourounded by foam. ...
But it is not shielded against radio frequency interference. For example: desktop PCs are shielded with a thin aluminum panel if case is plastic. If the case is made from metal it is already shielded. otherwise you would see interference on the your monitor and TV sets.

Sounds like the car generates a lot of radio frequency (RF) for whatever reason. If you cannot isolate the source of the RF then isolate the recorder. Try shielding it from the RF by simply wrapping the outside with a couple of layers of aluminun should work. Alternative, the recorder could fit in a metal tool box. That should work too.


Besides being a snomo nut I am also a hifi nut.

krellheat....the recorder is not shielded sense it is only in a plastic case. on eproblem we have is that the recorder needs to get air flow to cool down. that may cause a problem too. we will figure something out.
thanks again.

Shielding does not have to be solid--it can be aluminun screening or perforated metal. Just something to absorb the RF before it reaches electronic components inside the unit.

You guys are definitely on the right track with the shielding... just one point worthy of note - make sure that the shield is grounded to something, or your 'shield' becomes an 'antenna'.

I have seen electronics in certain factories cased in chicken wire to prevent rf interference,it's some thing we used to see a lot with electronic scales with millivolt signals-sometimes keying a radio would set the readouts off.
You probably need to find a way to disupt the signal from interfering with the recorder-be it through grounding or somehow isolating the device from the waves.

hey dawg, im no electrical engineer but i do have some input,you can get an inline noise filter to keep out some of the noise coming throgh the elec.,harness. also i know that when i used to build pleasure yachts we used to twist our wires together in the harness anywheres we could, it acts as its own shielding device,it works well.all you have to do to do this is before you connect all your wires together hook one end ,put the other in a cordless drill pull some tension on it and operate the drill(go slowly) you dont need it very tight just twisted a little will cut out rf interferance. the reason we used to do this is because of the radar on the boats so i know it works.hope this helps