Ectron 441A, Инструкция по эксплуатации, Страница: 43 / 74

LATENCY
Latency is the time required for the output to respond to a change in input frequency. Latency
in the Model 441A is within 1 ms of each falling edge of the input signal for input frequencies
above 1 kHz, and within 1 ms
+
1
⁄
f
in
for frequencies below 1 kHz.
FRONT-PANEL INDICATION
The display on the front panel indicates the frequency of the incoming signal with a resolution
of five digits and the pulses per revolution setting of the periodic-error filter. Displaying the
input frequency serves several purposes during setup and operation of a test. First, it gives
the operator a “ warm and fuzzy” feeling knowing that everything works. It confirms that
the pickup device is working and connections to the converter are correct. If the frequency
is approximately correct, it shows that the signal level is probably acceptable to the converter.
During the test, an operator can monitor the read-out to get a quick look at the frequency
data. The green front-panel LED will extinguish if no signal is present, and the display will
read 0.0000. If the input signal exceeds 50 kHz the read-out will continue to read correctly
until the frequency exceeds 63 kHz. Above this frequency, the read-out will show dashes.
(The analog output also will continue to be correct until it reaches approximately 11 V.)
The setting of periodic filter has also been selected for this screen because an incorrect
setting such as the wrong number of pulses per revolution increases noise as can using it
above 1 kHz.
CALIBRATION
The
CAL
ibration mode allows the operator to set a calibration signal from 0 Hz to 50 kHz
in 1 Hz increments. When
CAL
is enabled, the analog output assumes a voltage value of
the
CAL
frequency in accordance with the frequency and voltage set points. The calibration
circuit does not test the input-signal-conditioning circuitry and ignores any input signal.
To turn on the calibration signal, go to the
CAL
screen, adjust the frequency, and set
OFF-ON
to
ON
. At this time, the output will assume the analog value corresponding to the frequency
and voltage set conditions. This output and the
CAL
screen will remain until it is exited or
the
CAL
is toggled
OFF
.
Figure 4-9
Strip-chart Recording of ABS Action
Model 441A Applications
4-13