I connect my sensor to 3 channels of my 16 bit A/D, each of which are 
set to differrent gains/maximum input voltage.  In realtime, the 
software uses the highest gain channel that isn't saturated for each 
sample.  This, in some respects, gets about 21 bits of resolution out of 
my 16 bit A/D.  Obviously the voltage resolution of the signal 
deminishes as it moves up the channels but it avoids saturation and you 
don't need the highest voltage resolution as the signal increases in 
magnitude.

Ian

Barry Lotz wrote:

> Hi Ted
>   It seems that we all have the issue of how sensitive to make the 
> system. More sensitive and you can pick up more distant events but if 
> it is too sensitive one gets clipped signals during stronger events. 
> Larry's circuits and others have two recording gain levels which is 
> probably the best but one could set the gain lower and use a higher 
> bit A/D converter like 24 bit. I have plotted magnitude vs distance vs 
> count for my systems and have selected some level which is ok with me 
> for the time being but like any hobby, there is always a desire to 
> improve.
> Regards
> Barry
>  
>
>     snip-
>      
>     Q 2. What are the expectations of a Lehman sensor?  I know that
>     depends on many factors, and not the lease of which is the quality
>     of the sensor, and its environment, as well as the type and
>     location of the events.  But just in general terms. The AS1, which
>     is not a Lehman suggest one should be able to see 6.0m from
>     several thousand mile away, or something like that.
>     The reason I ask, I do hear statements, both over and under my
>     expectations.  Time will tell, but I wanted your opinions.
>      
>     Cheers, Ted
>      
>




  
  


I connect my sensor to 3 channels of my 16 bit A/D, each of which are
set to differrent gains/maximum input voltage.  In realtime, the
software uses the highest gain channel that isn't saturated for each
sample.  This, in some respects, gets about 21 bits of resolution out
of my 16 bit A/D.  Obviously the voltage resolution of the signal
deminishes as it moves up the channels but it avoids saturation and you
don't need the highest voltage resolution as the signal increases in
magnitude.



Ian



Barry Lotz wrote:

  
Hi Ted
  
  It seems that we all have the issue of how sensitive to make
the system. More sensitive and you can pick up more distant events but
if it is too sensitive one gets clipped signals during stronger events.
Larry's circuits and others have two recording gain levels which is
probably the best but one could set the gain lower and use a higher bit
A/D converter like 24 bit. I have plotted magnitude vs distance vs
count for my systems and have selected some level which is ok with me
for the time being but like any hobby, there is always a desire to
improve.
  
Regards
  
Barry
  
 

  

  
  

    
snip-
    
 
    
Q 2. What are the expectations of
a Lehman sensor?  I know that depends on many factors, and not the
lease of which is the quality of the sensor, and its environment, as
well as the type and location of the events.  But just in general
terms. The AS1, which is not a Lehman suggest one should be able to see
6.0m from several thousand mile away, or something like that.
    
The reason I ask, I do hear
statements, both over and under my expectations.  Time will tell, but I
wanted your opinions.
    
 
    
Cheers, Ted