Hi.

I did some tests:

50Hz issue, its from the computer and the ADC board..managed to minimize
the problem changing some connections to earth. Just doing the simple test
of using a laptop and changing from battery to ac adapter is very noticed
the increase of 50Hz noise.

>10s noise, i tested with L15b geophones and the issue remains, so most
probably its a issue from the ADC board.

About the geophone only giving 3800ohm, its a mystery..i will do some more
tests.

Thanks for help.

Best Regards,
Tiago.

2012/8/3 Tiago A. 

> Thanks for the answers.
>
> @Angel
> This is 15mnts results with the geophone in the horizontal position.
> http://dl.dropbox.com/u/15802004/horizontal.sac
>
> @J=F3n
> I do have a lot of noise >5Hz due living in a urban area, but the noise
> i=B4m worried about is below 0.1Hz. The 50Hz noise comes from the electri=
cal
> grid, here in Portugal the electrical grid works at 50Hz, other countries
> usually work at 60Hz. I dont know how long i have the 50Hz issue, i=B4m u=
sing
> 28SPS for almost 6 months, only yesterday i increased the sample rate and
> found out this issue.
>
> Whatever i did yesterday, the results got worse <0.1Hz.
>
> Best Regards,
> Tiago.
>
>
> 2012/8/2 J=F3n Fr=EDmann 
>
>> Hi,
>>
>> This might be traffic (car, trains, people) or wind noise. This noise is
>> common from 3Hz and upwards. If you see period change in the noise
>> during the day and weekend, it is traffic noise from cars nearby. But
>> this type of sensors can pick up car noise from up to 5 km away if the
>> ground allows for it (mud, clay type of soil).
>>
>> Best regards,
>> J=F3n Fr=EDmann.
>>
>> On m=E1n, 2012-07-30 at 02:07 +0000, Tiago A. wrote:
>> > Hi.
>> >
>> > Im using a L4 1Hz geophone and for almost a month im struggling with
>> > high noise from 10s up to ..., but from <10s it looks good. The noise
>> > comes and goes, this image is self explaining:
>> >
>> > http://dl.dropbox.com/u/15802004/noise.png
>> >
>> > Changed cables, re centered the geophone, but didint help..the
>> > geophone is connected directly to a ADC without damping, external
>> > amplification or filtering, i only use digital filtering from the ADC.
>> > Before this issue start, i had a pretty clean spectrum >10s for almost
>> > 6 months, which allowed me to received LQ and LR from some strong
>> > events.
>> >
>> > This sac contains 15minutes with high noise >10s, notice that at 3:37
>> > it recorded a Ml2.1 at 70km.
>> > http://dl.dropbox.com/u/15802004/noise.sac
>> >
>> > What could be the problem?
>> >
>> > I appreciate any help.
>> >
>> > Best Regards,
>> > Tiago.
>> >
>> >
>> >
>>
>>
>> __________________________________________________________
>>
>> Public Seismic Network Mailing List (PSNLIST)
>>
>> To leave this list email PSNLIST-REQUEST@.............. with
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>> See http://www.seismicnet.com/maillist.html for more information.
>>
>
>
Hi.

I did some tests:

50Hz issue, its from the computer and t=
he ADC board..managed to minimize the problem changing some connections to =
earth. Just doing the simple test of using a laptop and changing from batte=
ry to ac adapter is very noticed the increase of 50Hz noise. 



>10s noise, i tested with L15b geophones and the issue remains, so m=
ost probably its a issue from the ADC board. 

About the geophone onl=
y giving 3800ohm, its a mystery..i will do some more tests.

Thanks f=
or help.


Best Regards,
Tiago.

2012/8/3 Tiag=
o A. <tiagoagre@.........>


Thanks for the answers.

@Angel
This is 15mnts results with the ge=
ophone in the horizontal position.
http://dl.dropbox.com/u/15802004/h=
orizontal.sac




@J=F3n
I do have a lot of noise >5Hz due living in a urban area, =
but the noise i=B4m worried about is below 0.1Hz. The 50Hz noise comes from=
 the electrical grid, here in Portugal the electrical grid works at 50Hz, o=
ther countries usually work at 60Hz. I dont know how long i have the 50Hz i=
ssue, i=B4m using 28SPS for almost 6 months, only yesterday i increased the=
 sample rate and found out this issue.




Whatever i did yesterday, the results got worse <0.1Hz.

Best =
Regards,
Tiago.


2012/8/2 J=
=F3n Fr=EDmann <jonfr@.........>



Hi,



This might be traffic (car, trains, people) or wind noise. This noise is
common from 3Hz and upwards. If you see period change in the noise

during the day and weekend, it is traffic noise from cars nearby. But

this type of sensors can pick up car noise from up to 5 km away if the

ground allows for it (mud, clay type of soil).



Best regards,

J=F3n Fr=EDmann.



On m=E1n, 2012-07-30 at 02:07 +0000, Tiago A. wrote:

> Hi.

>

> Im using a L4 1Hz geophone and for almost a month im struggling with
> high noise from 10s up to ..., but from <10s it looks good. The noi=
se

> comes and goes, this image is self explaining:

>

> http://dl.dropbox.com/u/15802004/noise.png

>

> Changed cables, re centered the geophone, but didint help..the

> geophone is connected directly to a ADC without damping, external

> amplification or filtering, i only use digital filtering from the ADC.=


> Before this issue start, i had a pretty clean spectrum >10s for alm=
ost

> 6 months, which allowed me to received LQ and LR from some strong

> events.

>

> This sac contains 15minutes with high noise >10s, notice that at 3:=
37

> it recorded a Ml2.1 at 70km.

> http://dl.dropbox.com/u/15802004/noise.sac

>

> What could be the problem?

>

> I appreciate any help.

>

> Best Regards,

> Tiago.

>

>

>





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_____



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To leave this list email PSNLIST-REQUEST@.............. with

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See h=
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