Frequencies greater then 20 MHz may be applied, but they will be averaged
during a 50 ns gate time.
(b) Period Average. When the GATE TIME switch is set to any other
position then MIN, the counter averages multiple periods.
Averaging
increases the accuracy and resolution of the measurement. Input frequencies
are in the 50 uHz to 500 MHz range. The actual gate time is determined in
the same manner as that described for Frequency Mode.
(3) Time Interval Modes.
The counter measures time intervals from
Channel A to Channel B; that is, Channel A starts the measurement and
Channel B stops the measurement. Time between points on a single waveform
can be measured by connecting the input signal to Channel A jack and placing
the Input Amplifier Control switch to COM A.
Under these conditions, the
slope and level controls of Channel A and Channel B allow variable
triggering on either the + or - slope.
With the Input Amplifier control
switch set to SEP, measurements can be made between points on separate
(a) Single Time Intervals.
Single time intervals down to 10 ns
are measured with the GATE TIME switch set to MIN.
The gate time is one
time interval for repetition rates of less than 20 MHz.
Thus, if two or
more time intervals occur within 50 ns, they will be averaged.
(b) Time Interval Average.
The counter averages multiple time
intervals when the GATE TIME switch is set to any position other than MIN.
The maximum repetition rate is 50 MHz (10 ns time interval plus 10 ns
deadtime = 20 ns period or 50 MHz). To average, the time interval must be
less than the selected gate time.
(4) Ratio Measurements.
The ratio between two frequencies can be
determined by connecting one signal to Channel A and the other to Channel B.
If the higher frequency is connected to Channel B, the ratio will be greater
than one. For instance, a 100 MHz signal connected to Channel B and a 50
MHz signal connected to Channel A will result in a ratio of 2. The answer
for a ratio measurement is a unitless figure.
(5) Totalize Mode.
The START and STOP positions on the FUNCTION
switch allow manual opening and closing of the counter's main gate.
The
Input Amplifier Control switch must be placed in SEP. When the switch is in
the START position, the counter totalizes the number of times the input
signal passes through the-Channel A trigger point.
The GATE TIME switch
does not affect the displayed result in any way.
(a) Both Channels Totalized.
When the Input Amplifier Control
switch is set to SEP, Channel A and Channel B signals can be totalized
simultaneously. The displayed result is a function of the
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