Our seismographs do not require periodic calibrations in that they do not have any adjustable parameters. With that being said, we do recommend that they are checked for performance and routine maintenance to include intensive analog tests of the acquisition circuitry. A reasonable interval would be around every 5 years for normal usage.
During these tests we verify that the seismograph analog performance meets our specifications by using a seismic test system. This system incorporates a standard reference oscillator and precision resistor networks to inject known signals into the seismograph. We then use algorithms in our software to calculate the response and performance of the analog circuits.
This "performance test" is run whenever we receive an instrument in for repair or evaluation. Some of our customers do prefer to have the performance of their instrument checked on a periodic basis especially if they are required by their clients, for example the NRC. We offer these nontraceable recertification’s to include a calibration certificate and test results for a fee of $300.
If you would like us to perform performance verifications and a system evaluation please reserve an RMA and obtain shipping instructions.