Philips 6652C - Page 34

The MATHematics Function
The MATH function can be used to store constants
and offset factors which will modify the dis-
played result, The example used so far has been
the case in which a voltage signal (Vpp) from a
transducer could be converted to a value of
volume or other units. Another case in which
MATH could be used is to store a factor which
compensated
for differing delays between chann-
els.
The HOLD OFF Function
The HOLD OFF function is used to avoid superim-
posed or leading edge noise on input signals.
When used, however, the PM 6654 's performance
becomes
identical with that of the PM 6652 (see
chapter 9). Applications for HOLD OFF are:
- Superimposed noise on carrier frequencies in
the range 5 Hz ..• 150 kHz can be suppressed,
- Leading edge noise can be suppressed on sig-
nals in the frequency range 5 Hz to 150 kHz.
HOLD OFF is disabled in the functions PHASE A-B
and DUTY FACTOR A. It should not be used in the
function RISE/FALL TIME A.
HOLD OFF cannot be applied to any function
involving Channel C.
PHASE Measurements
The limiting voltages for PHASE measurements
are:
- 100 mVRMS to 3.5 VRMS or
- 1 VRMS to 35 VRMS (x10 attenuation)
A higher input voltage will cause waveform dis-
tortion, while lower voltages will result in in-
accuracy. Maximum frequency is 2 MHz.
DUTY FACTOR Measurements
The highest frequency at which DUTY FACTOR can
be used is 2 MHz.
Voltage Measurements
Accurate val tage measurement is possible up to
20 MHz . Frequencies between 20 and BO MHz can
also be measured but with reduced accuracy.
External Control - INT/EXT STD IN
When the INT /EXT STD IN switch is in the down
position, the counter will expect an external
standard reference signal. Rules applicable to
the use of such a signal are:
- If there is no external signal, the counter
will display error E4 after the power on se-
quence (see chapter 8 "Performance Check"), If
the E4 error is RESET and there is still no
signal, either :
- The PM 6652 will not measure.
The PM 6654 will attempt to measure frequen-
cies and single time intervals, but t:he re-
sults will be inaccurate.
When using an external signal for time interval
averaging measurements, the standard reference
signal should not be synchronised with the input
signal.
The INT/EXT STD IN control cannot be stored as a
stored panel program parameter.
ARMING/FREQ AVG/EXT GATE/OFF
When this control is in the EXT GATE position,
the counter will expect an external control sig-
nal, and will not measure until such a signal is
supplied, If it is set to ARMING or FREQ AVG,
the counter will measure when the control signal
is absent, or TTL-low.
When stored in a stored panel program, the ex-
ternal control state can be overridden by swit-
ching to a new position. For normal operation,
the switch should be set to OFF. The functions
are applicable as follows:
ARMING
AVG
To all but PHASE, DUTY FACTOR and
TOT A/MAN measurements.
To FREQ A, FREQ C and PERIOD A and
TIME A-B measurements.
EXT GATE To FREQ A, FREQ C and Period A measure-
ments. Example applications are multip-
le burst frequencies and masked time
intervals. Note that if RF burst are to
be measured using FREQ C, the burst
should contain at least 32 CW cycles.
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