PSN-L Email List Message

Subject: Re: Event 091025.105300 as seen from GVA ??
From: "Geoffrey" gmvoeth@...........
Date: Sun, 25 Oct 2009 17:20:03 -0700


Thanks, that sounds very reasonable.

I may consider changing things
But think not able to go higher than
10 bits since the lower two seem noisy
and I do not understand why since
with no input but a dummy 5K
resistor I see the lower bits
bouncing with no input at all.

I have not played with this noise
recently just am using 8 or 9 bits
with 9 bits for a 6Db of gain boost.

Using 10 will require a program change
as well as testing to see this does
alteration to a greater bit size
does not change my sample rate
which is very sensitive to exactly
how the DOS is programmed.
Mainly the kind of memory used
like HUGE or Virtual.
Virtual in power basic seems
considerably slower than Huge.

I do a lot of stuff between each
loop of sample taking
(such as time calibration) and it seems
slow or fast machine the limiting factor
is staying in REAL mode memory instead of
virtual mode within DOS.

Real Mode = first 1MB
Protected Mode = all above 1MB

EMS seems faster than XMS.

????
Do not understand any of this
but I DO need consistent speed
between each sample taking.

The programming is critical to
achieving a steady sample rate
equal to the tic timer within the
computer.

Possibly some commands will disable
the interrupt timer used for the tic counter.

Simply lowering the gain or possibly
using a log amplifier may be other choices
for me to consider.

regards
geoff



----- Original Message ----- 
From: "Larry Cochrane" 
To: 
Sent: Sunday, October 25, 2009 4:08 PM
Subject: Re: Event 091025.105300 as seen from GVA ??


> Hi Geoffrey,
> 
> This is happening because your system is saturation. Looking at your event file it 
> looks like you are using a 8 Bit A/D converter. Upgrading to a 12 or higher bit 
> converter would give you a lot more dynamic range so this would happen less often.
> 
> Regards,
> Larry Cochrane
> Redwood City, PSN
> 
> Geoffrey wrote:
>> Hey guys;
>> 
>> In Winquake
>> 
>> event file: 091025.105300 from GVA
>> When I integrate this event the ground seems
>> to drop at somewhere in the S or L wave and does
>> not return to normal ?
>> 
>> Does anyone understand this integrated waveform ?
>> 
>> It looks to me like only the DC blocker circuit
>> is returning the signal to its baseline.
>> 
>> I have seen this before but do not understand it.
>> 
>> In my wildest imagination I can in no other way
>> explain this results of the integration.
>> 
>> Is Arizona slowly sinking into the Earth ?
>> Will we have another ocean where there used to be desert ?
>> 
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