Hi Casey -- I was thinking if you were looking at the output as a file of numbers on the computer. If you were to take 100 readings, then throw out the highest and lowest (assume they might be glitches from power lines, etc), then what are the highest and lowest readings that are left. Here's another way I've heard to measure random noise with an oscilloscope: Feed the signal source into a vertical channel of the scope, and adjust the vertical sensitivity so the the trace is around two major divisions on the screen. Then connect another vertical channel to the same signal and set its sensitivity to the same value as the first channel. If the noise is random, each channel's trace will be brightest near its center and get dimmer toward the top and bottom edges of that trace. Now adjust the vertical position of one of the channels until the traces overlap in such a way that the brightness of the display between the two channels is almost constant. That is, at the point where the lower part of the upper trace is starting to dim, the upper part of the lower trace is brightening so as to compensate. Then ground the input to both scope channels and observe the difference in vertical position between the two traces. The number of divisions between the traces times the vertical sensitivity is a measure of the noise of the signal. Unfortunately, I don't remember if this number is supposed to be peak, RMS, or what. Maybe someone out there knows. Regards, Karl --On Thursday, May 24, 2001 17:35 -0700 Casey Cranewrote: > Karl, > > In reguards to to reply, first thanks, then How do you define "Counts of > noise" ? I have an O'scope But how do I measure this random or > psuedo-random stuff without a spectrum anylizer ? > > My AtoD is quiet as a mouse. I'm using an ADC0809 eight channel > AtoD and am using but four of these channels. I'm using the printer LPT1 > interface. __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>