(...continued)   Changes affecting the sampling rate can cause similar cases of undersampling. Consider again the same digital measurement system acquiring data at 100 samples/second and a single strain gage on a test part vibrating at 10Hz. As before, this sampling rate of 100 samples/second/channel provides for 10 datum/cycle/channel, and should be adequate to reconstruct the signal in the time domain. But if the number of channels is increased to 10 and a multiplexer is used to sample each channel sequentially, the scanning rate is reduced to only 10 scans/second/channel and the system can now provide for only 1 datum/cycle/channel. While the throughput rate and frequency of the signal were unchanged, the data became meaningless when the number of channels (and thus the sampling rate) was changed.   The only cure for undersampling, of course, is to increase the sampling rate. For systems operating at a fixed throughput rate (like System 4000, the original Vishay Measurements Group Data System), that usually means decreasing the number of channels being sampled. More sophisticated systems -- like the Vishay Measurements Group System 5000 and System 6000 Data Systems -- allow the sampling (scanning) rates to be adjusted until the maximum scan rate, maximum throughput rate, or both are reached. System 5000, for example, can scan at 1, 10, and 50 samples/second/channel with a maximum throughput of 12,500 samples/second/system. System 6000 will scan at 10, 100, 200, 500, 1000, 5000, and 10,000 samples/second/channel with a maximum throughput of about 200,000 samples/second/system when using Model 6100 Scanners , and virtually unlimited throughput when using Model 6200 Scanners .   (continued...)   Page 16 of 24