Kenwood FC-758 Instruction Manual page 23

Figure 4 shows display examples.
Figure 4 a indicates the value of " 1234.567" w i t h
k H z / ^ s L E D (3) active. T h i s means t h a t the
counter is now measuring the frequency or period
selected by F U N C s w i t c h
If it is assumed t h a t a frequency is being measured,
the display resolution value is 0.001 kHz, t h a t is, 1 Hz,
T h i s means t h a t the gate time (display resolution)
has been set to 2 . 7 s / 1 0 s .
W i t h those functional parameters left unchanged,
use the F U N C switch to select the M H z / 1 0 0 M H z
mode. The display value w i l i change to the one
as shown in Figure 4 b. T h i s means t h a t the same
frequency is s t i l l being measured but the
measurement value is now displayed in M H z . In
other words, the display resolution value has not
been changed w i t h G A T E switch
display resolution value has changed f r o m 1 Hz
( 0 . 0 0 1 k H z ) to 10Hz (0.0001 M H z ) .
W i t h this gate time value unchanged, use the
F U N C switch to select the prescale mode ( C H
B / 1 . 3 G H z ) . The measurement value on the display
w i l l be change to the one as shown in Figure 4 c.
T h i s means t h a t the display resolution value has
@ .
@ but the
changed to 100Hz (0.001 M H z ) .
- Figure 4 d shows the typical display example in
the event t o t a l measurement mode. The t o t a l
measurement value does not require any display
unit. A s a result, it is displayed in integer
display d a t a following the decimal
Note t h a t l o w - o r d e r digits may be d i f f i c u l t to
view because they change very quickly as
frequencies becomes higher and higher.
5 - 4 - 2 . Unstable Display
The least significant digit ( ± 1 digit) of a
measurement value may have an error a t digital
measurement. In this section, errors other than
t h a t w i l l be explained.
If noise or ringing is superimposed on an input
signal, these unexpected signal waves may work a s
pseudo trigger signals to cause unstable display.
Under such operating conditions, measurement
values may be output to display ©
true. However, they might be inaccurate due to the
superimposed noise or ringing.
T o solve the above problems, use the internal
attenuator circuit and low pass f i l t e r ( L P F )
circuit.
(no
p o i n t ) .
as if they were
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