Special Stage Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter · #1 ·
So, we've successfully installed the Terratrip 303 and the DSI probe, however, we've got an odd error. The DSI probe seems to be picking up random noise or voltage levels.

The problem, from what I can tell, is between the DSI probe and the green pulse wire on the Subaru WRX. This is based on looking at the impulses coming into and leaving the DSI probe on a Fluke Scopemeter. The oscilloscope shows a perfectly fine square wave coming from the DSI, however, on the input line coming from the green pulse wire into the DSI, I see considerable noise, a sort of ringing on the square wave.

Now, we've checked to make sure that the pickup line isn't parallel any other wires in which it could be picking up additional voltage through inductive coupling. So, I don't *believe* that could be the problem.

Before I start hacking away at the wire and whatnot, has anyone here also seen this problem? Does anyone know what the nominal voltage is of the impulses coming from the green pulse wire by the tranny is? If so, what is it? One possibility I have is running a diode in series with the impulse input line so that I voltage limit the line.

If anyone has had a similiar issue, what did you do to fix it? Thanks everyone.

Mel

Melody Yoon
Co-Driver Car # 334
Amateur Radio Operator, KF6RMW
 

·
don't cut
Joined
·
2,252 Posts
RE: electrical noise -Terratrip 303+

Although I have no idea if it will work on the signal wire, you may wanna look into a noise suppressor. We put one on the power input on the Eclipse, and it solved all kinds of problems. About $25 from Radio Shack.

Dennis Martin
[email protected]
920-432-4845
 

·
Registered
Joined
·
533 Posts
RE: electrical noise -Terratrip 303+

I don't think that would work, as the noise suppressor traps fluctuations in the voltage, and what is the signal but a fluctuation in the voltage.

I believe that the output of the VSS sender is 0-5v. (but don't quote me on that one...)

jb
 

·
If money were no object
Joined
·
272 Posts
RE: electrical noise -Terratrip 303+

Have you tried to twist the signal wires between the sensor and the terratrip, this will help to shield the wires against white noise through the wiring. The wires should be twisted from one end to the other, but only works if there is more than one signal wire. Sorry but I don't have enough experiance with the Terratrip to know if its a one wire lead or more.
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #5 ·
RE: electrical noise -Terratrip 303+

Well, one of the things I'll be doing is wrapping the input impulse wire around a toroidal core to cut out common mode AC hum, however, what I don't know is if that'll also cut out the impulse itself. Also, I need to run an RF choke on the negative ground lead going from the probe so that AC doesn't get into the system over ground.

Thanks everyone for ideas. Keep them coming. :)

Mel

Melody Yoon
Co-Driver Car # 334
Amateur Radio Operator, KF6RMW
 

·
don't cut
Joined
·
4,075 Posts
RE: electrical noise -Terratrip 303+

I cheated and looked you up on the FCC list. Extra class! You have probably forgotten more about noise elimination than I ever knew. And I am a profession electrical engineer. Let us know what works.
Richard
KD5PXM
(technician to save time)
 

·
Registered
Joined
·
125 Posts
RE: electrical noise -Terratrip 303+

Well, shoot. We tried putting the aforementioned toroidial cores into the system today, and they didn't help a bit. The behavior we're seeing is that the computer will be fine until the car begins moving, at which point it will usually (but not always, darn it) start clicking off distance at a steady, but very rapid rate. The rate does not appear to change with the car's speed, sometimes even continuing when the car is stopped! It really seems like the signal wire we've got coming into the probe is picking up something other than the transmission pulses from the green wire that we're tapped into.

--
Neil Bliss
wrx, ClubRally #334
 
1 - 7 of 7 Posts
Top