Trinity EMI jamming GPS and Key FOB

gizmodo · Post by **gizmodo** » Wed Apr 06, 2011 8:12 am

duster360 wrote:Your tin foil needs to connected to the CBA ground plane to be an effective EMC sheild.

In English please.

duster360 · Post by **duster360** » Wed Apr 06, 2011 9:23 am

gizmodo wrote:
duster360 wrote:Your tin foil needs to be connected to the CBA ground plane to be an effective EMC sheild.
In English please.

Run a wire from the ground(#4 or #5 pin of the ALDL), to your tin foil hat,,I mean sheild. See if anything improves.

I'm leading a team to respin a CBA(circut board assembly) for a Hall effect sensor we make. The sensor as a pretty good EMC sheilding so I picked up a few things from the EE nerd herd.

gizmodo · Post by **gizmodo** » Wed Apr 06, 2011 9:57 am

ALDL? Sorry you have to be specific here I just browse the web all day, I'm not one of those fancy engineering types. Will foil be an okay material to test with, or should I try something else?

Post by **mikel** » Wed Apr 06, 2011 10:04 am

OBD2 port.

duster360 · Post by **duster360** » Wed Apr 06, 2011 10:27 am

gizmodo wrote:ALDL? Sorry you have to be specific here I just browse the web all day, I'm not one of those fancy engineering types. Will foil be an okay material to test with, or should I try something else?

Yeah, what Mike said.

Aluminum is fine as long as you can maintain a reliable electrical connection.
If you had copper foil, you could solder to it.

gizmodo · Post by **gizmodo** » Wed Apr 06, 2011 10:51 am

Cool, I'll see what I can do this week. I'm going to see if I can find some copper foil, sounds like a fun thing to do!

gizmodo · Post by **gizmodo** » Thu Apr 07, 2011 11:32 am

Okay scratch that copper foil is too expensive for testing. Aluminum it is!

gizmodo · Post by **gizmodo** » Tue Apr 19, 2011 10:08 pm

I tried this tonight and I have come to the conclusion it is the display causing the problem. I wrapped the Trinity in foil and the display separately. I tried the keyfob without grounding either foil ball and the foil seemed to make things worse. I couldn't unlock the doors even while sitting in the car. Next I grounded foil wrapping for both the Trinity and the display to pin 5 of the OBDII port. This accomplished nothing. Next I tried grounding it to the chassis. Still didn't help. Then I tried grounding them to both the chassis and the OBDII port and it still didn't help. Next I removed the foil from the display and tried again. Now I could get the keyfob to work about 1 out of 5 times from about 2 feet away, which is what I have been experiencing all along. Finally I just removed all the foil.

The display is made by One Stop Displays, and the part number is:OSD035TN01 The Trinity has the v6 version which is the touchscreen. I found the datasheet for it (http://cec-mc.ru/upload/techinfo/osd/OSD035TN01.pdf), but I'm not sure I want to try to add grounds to the cable. Maybe you smart EE guys want to take a look.

I'm out of ideas unless anyone has anything else I can try. I suppose I could try running the Trinity without the display to see if that really is the problem. Would that work Mike or could that damage the Trinity?

Post by **mikel** » Wed Apr 20, 2011 9:22 am

Not sure, let me see if I can find out on that...

gizmodo · Post by **gizmodo** » Wed Apr 20, 2011 8:31 pm

I can confirm that it is display. I turned the Trinity on and got into the "home" screen. My keyfob had very little range. I unplugged display with the unit still powered up. I confirmed the Trinity was still on by connecting a laptop and pulling files off. I had plenty of range with the keyfob with the display unplugged. When I plugged the display back it the Trinity was still on the home screen. The display is certainly appears to be the problem here.

Nightshade · Post by **Nightshade** » Thu Apr 21, 2011 12:09 am

gizmodo wrote:I can confirm that it is display. I turned the Trinity on and got into the "home" screen. My keyfob had very little range. I unplugged display with the unit still powered up. I confirmed the Trinity was still on by connecting a laptop and pulling files off. I had plenty of range with the keyfob with the display unplugged. When I plugged the display back it the Trinity was still on the home screen. The display is certainly appears to be the problem here.

RF interference from LCD displays is pretty common. LCD displays are usually shielded.. I believe it is the CFL back-light that causes it.. throws a ton of RF..

there is non-conductive coated foil out there for this sort of thing.. could stick it to the back of the display and ground it if it's missing the RF shield.. if the shield is in place, make sure it's grounded properly. will be hard to eliminate it if it's a poorly designed LCD panel.. you can't exactly create a Faraday cage if you need to still see the screen.

Hopefully Diablosport can look into this further... maybe they can engage their LCD vendor and come up with some sort of a fix...

gizmodo · Post by **gizmodo** » Thu Apr 21, 2011 8:10 am

The LCD they use is longer available. It appears as though OSD has replaced it with a new one. As for the shielding, there is some type of metal around the back of the LCD, but I don't know if that is to protect it or act as a shield. I understand LCDs give of interference, but many cars now come with LCDs or have them added later and they don't cause these problems so there has to be a solution.

gizmodo · Post by **gizmodo** » Thu Apr 21, 2011 8:59 am

Here is OSD's response to me email:

I appreciate your diligence in determining the cause of the interference you
are experiencing though there is nothing that OSD can do to support your
issue. We offer no drop in replacement part for this display and the part
has been discontinued for a few years now.

This is solely a discussion you need to have with Diablo Sport.

Goemon · Post by **Goemon** » Tue May 03, 2011 2:45 pm

I am getting the same problem now. We need an FFT analyzer!?
Did anyone try ferrite magnetic core at the cable end?

gizmodo · Post by **gizmodo** » Wed May 04, 2011 8:09 am

It isn't the cable, my posts right above yours show it is the display.