Getting Started
CMC251 User Manual
5
13. PRESCALE Button. Divides the frequency of the signal applied
to CHANNEL A INPUT by a factor of ten and sets the measure-
ment units indicator to either MHz or kHz
s. When pushed in,
frequencies up to 100 MHz or periods up to 0.04
s can be
measured. In the out position, frequencies up to 10 MHz or
periods up to 0.4
s can be measured.
14. Mode Indicators. These LEDs light to indicate the present mode
settings. One of the following modes is indicated:
H
FREQ A—The Frequency A mode measures the repetition
rate of the signal applied to the CHANNEL A INPUT. In this
mode, measurements from 1 Hz to 100 MHz can be made.
H
FREQ B—The Frequency B mode measures the repetition
rate of the signal applied to the CHANNEL B INPUT. In this
mode, measurements from 80 MHz to 1.3 GHz can be made.
H
PERIOD A—The Period A mode measures the time it takes
for one cycle of the signal applied to CHANNEL A INPUT to
be completed.
H
PULSE A—The Pulse A mode measures the width of the
positive pulses of the signal applied to CHANNEL A INPUT.
The Pulse mode can also measure the negative pulse of the
input signal when using the external control input connector
located on the rear panel. See Making Pulse-Width Measure-
ments on page 13 for a description of its use.
H
TOTAL—The Totalize mode counts signal events applied to
CHANNEL A INPUT, incrementing one count for each
event. The display is updated continuously unless the HOLD
button is pressed. The count resumes when the HOLD button
is released. The Totalize mode can also be controlled
remotely with the use of the external control input connector
located on the rear panel.
H
CHECK—The Check mode uses the internal time base as a
signal source to make a general check of the operating
system. The display will indicate a frequency of 10 MHz.
Summary of Contents for CMC251
Page 1: ...User Manual CMC251 1 3 GHz Frequency Counter 070 8527 03...
Page 4: ......
Page 10: ...General Safety Summary vi CMC251 User Manual...
Page 18: ...Getting Started 8 CMC251 User Manual...
Page 28: ...Reference 18 CMC251 User Manual...
Page 34: ...Appendix A Specifications 24 CMC251 User Manual...