In a message dated 2006/11/30, tchannel@.............. writes:

> Hi Jim,  At night time the noise stops as suddenly as it begins, I think it 
> stops at around 4:30pm, starts at 8:35 to 8:50am.  Really quiet at night,
> I live 1/4 mile from a school, and crossing lights, but the noise continues 
> during Sat, Sun and Holidays when the school is inactive.
> I did remove the magnet during the noise, and the trace was dead quite, all 
> the noise stopped and started again when I replaced the magnet over the coil, 
> so I don't think it is RFI. 

Hi Ted,

       OK. Can you identify any 'typical sequence' types of signal?  Can you 
log the ~amplitudes?

       Now you have evidence that the noise isn't RFI or pickup from the 
house wiring, can you re-orient your sensor, say 20 degrees at a time at first, to 
determine the direction that it is coming from? If it is an external fixed 
source, there should be a direction which gives a minimum response.

       It can be quite difficult to identify a source just from a seismic 
trace. If it is a local source, there are likely to be a lot of associated high 
frequency signals. Do you have a geophone, or a piezo accelerometer, which you 
can use as a sensor to drive an audio amplifier / headphone system? Sounds 
carry quite a long way in the soil. I can pick up car tyre noise on the main road 
at about 1 km. This could help to direct your search.

       Regards,

       Chris Chapman
In a me=
ssage dated 2006/11/30, tchannel@.............. writes:



Hi Jim,  At night time the=
 noise stops as suddenly as it begins, I think it stops at around 4:30pm, st=
arts at 8:35 to 8:50am.  Really quiet at night,

I live 1/4 mile from a school, and crossing lights, but the noise continues=
 during Sat, Sun and Holidays when the school is inactive.

I did remove the magnet during the noise, and the trace was dead quite, all=
 the noise stopped and started again when I replaced the magnet over the coi=
l, so I don't think it is RFI. 




Hi Ted,



       OK. Can you identify any 'typical seque=
nce' types of signal?  Can you log the ~amplitudes?



       Now you have evidence that the noise is=
n't RFI or pickup from the house wiring, can you re-orient your sensor, say=20=
20 degrees at a time at first, to determine the direction that it is coming=20=
from? If it is an external fixed source, there should be a direction which g=
ives a minimum response.



       It can be quite difficult to identify a=
 source just from a seismic trace. If it is a local source, there are likely=
 to be a lot of associated high frequency signals. Do you have a geophone, o=
r a piezo accelerometer, which you can use as a sensor to drive an audio amp=
lifier / headphone system? Sounds carry quite a long way in the soil. I can=20=
pick up car tyre noise on the main road at about 1 km. This could help to di=
rect your search.



       Regards,



       Chris Chapman