In a message dated 26/01/00 20:52:58 GMT Standard Time, sean@........... 
writes:

<< In fact, the broadband response at the short period/high frequency end can 
cause problems with local site noise. My site here in the basement is about 
15 meters from a busy street.... Since I am using a vertical sensor, the long 
period noise is factors of 100
 less than the tilt noise a horizontal LP would be subject to. Which is why I 
wish that more PSN people would build vertical long period instruments. 

    Has there been any use of piezo electric accelerometers, either directly 
or with the output integrated to give velocity? (I am not talking about 
silicon chip devices.) What period would you recommend, please? I can extend 
the response out to ~15 sec without problems.

    Are there any other types of vertical seismometer that we can usefully 
construct, please? I was looking at your STM-8, but I can't get the spring 
and the whole project seems a bit too ambitious for me at the moment.

    Regards Chris

_____________________________________________________________________

Public Seismic Network Mailing List (PSN-L)