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9.2.1 Determination of
the click rate
9.2.2 Preliminary
Conformity and
Exceptions
9.2.2.1 Old and New
exceptions
The first step of the measuring process is to determine the click rate N in
the minimum observation time. This is done measuring the time needed to
count up to 40 clicks or 40 switching operations; the maximum time allowed
is anyway 2 hours (120 minutes), unless the cycle is determined by a
program which needs additional time to be terminated.
Therefore, if the equipment has a cycle and in this cycle less than 40 clicks
appear, then the cycle shall be repeated until 40 clicks are counted or until
the observation time is 2 hours.
If the equipment has a cycle and in this cycle more than 40 clicks appear,
the observation time is anyway determined by the cycle.
When the minimum observation time has been defined, it is possible to
calculate the click rate N using the simple relationship:
where n
is the number of clicks measured and T is the minimum
1
observation time.
However, in certain conditions – see CISPR 14-1 for further reference – the
click rate N must be calculated using a different approach:
where n
is the number of switching operations and f is a factor dictated in
2
the standard.
The click rate shall be determined at two frequencies: 150 kHz and 500
kHz.
Once the number of clicks – or switching operations – has been
determined, then some preliminary controls can be made to verify if the rate
is greater than 30 (fail conditions); if the measured clicks are conforming to
the definition of the standard; if there are exceptions applicable.
Thanks to its digital architecture, PMM 9010 can easily record and store all
the relevant parameters, keeping trace of all the events occurring during
the test and allowing the User to postprocess all these data; PMM 9010 will
also notify immediately the test results to the User.
The "Click" test also requires to verify if exceptions E1 to E4 are applicable.
While E1 and E2 are "old" exceptions easy to deal with, the new E3 and, in
particular, E4 are calling for a new hardware structure: an old click analyzer
is no longer compliant.
E3 is an additional counter, does not require additional memory and implies
only minor changes in the test flow, thus can be implemented in a relatively
easy way.
E4 is very demanding in terms of hardware requirements: a memory for
storing each disturbance duration and interval is required in order to post-
elaborate them, and it is mandatory to provide all the data in the test report.
Moreover, as the application of E4 is conditional to the final click rate N -
which in turn may prevent using E4 – the test flow significantly changes.
Only new analysers specifically designed – like the PMM 9010 - can
successfully meet the requirements of the standard and be compliant with
the new Click test criteria.
n
=
1
N
T
⋅
n
f
=
2
N
T
Click Mode Operating Instructions
9-3
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