Good Morning Richard,

It may not be EMF caused.

What is the sensing angle of the sensor compared to the axis of the 
car?  Moving the car causes a local disturbance due to the acceleration 
of a large mass.  I see that on my vertical seismometer repeatedly.

Another possibility is disturbance from the fan simply due to the change 
in air currents.  Three feet from a big moving object like a car is very 
close!

Previously, my vertical was located about 4 feet from the front of the 
kitchen stove but with a wall between and located on a concrete floor.  
I could see when my wife was cooking!  And she is not that big!

A good thing.  The noise pattern of the car must be much different from 
the pattern of a quake.  Not too hard to tell them apart.

The torque from  engine speed change should also be detectable but I 
would not expect a disturbance nearly as great as from the acceleration 
or deceleration of car movement.

Good Luck,

Roger

On 01-06-2011 12:01 AM, psnlist-digest-request@.............. wrote:
> Subject: Engine Start/Shutdown Noise Spikes From Automobile
> From:    Richard Schneider
> Date:    Wed, 5 Jan 2011 15:11:01 -0800
>
> --0016367fabe7a3aae50499217f59
> Content-Type: text/plain; charset=ISO-8859-1
>
> Situation:  High amplitude spikes when starting and again on shutdown of
> engine from automobile.
>
>   Sensor is about 3 feet from car.
>
> EMF appears to come from auto alternator since I can see it upon engine
> shutdown.
>
> Any suggestions would be appreciated to mitigate the EMF from the sensor
> pickup coil without relocating it.
>
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