Electro-Metrics EM-2115, Instruction Manual

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ELECTRO-METRICS EM-2115 2.0 OPERATING INSTRUCTIONS
(EM2115S2-16)
range (at the amplitude level of the input signal). To verify that the attenuation is
set for maximum range:
NOTE: The Sample Time Control must be set to the mid-range po-
sition for this procedure.
1) If the Overload Indicator is "ON", push the Increase Attenuation Switch
once. Wait one second and note if the Overload Indicator goes "OFF". If
not, continue increasing the input attenuation until the Overload Indicator
remains OFF.
2) If the Overload Indicator is "OFF", decrease the input attenuation (using
the Decrease Attenuation Switch) until either all input attenuation is re-
moved or the Overload Indicator comes "ON". If the Overload Indicator
comes "ON", increase the input attenuation until the Overload Indicator
remains "OFF".
The above steps will adjust the input attenuation of the EM-2115 to obtain the
maximum dynamic range at signal amplitude level being checked.
The amplitude indication on the digital meter will then be the CISPR level into the 50

input impedance of the EM-2115. If any pickup devices (antennas, probes, etc.) are used, the cor-
rection factors of the device must be added to the indicated meter reading to obtain the correct
amplitude level.
2.4.6.3 RMS Detector
The RMS Detector circuitry provides a true rms measurement of the input signal level
within the selected IF pass band of the receiver. The detector crest factor is 30 dB minimum.
Since all of the detector functions for the EM-2115 are calibrated in terms of the rms
equivalent, the RMS amplitude reading for an unmodulated CW signal will be identical to read-
ings in Peak, Quasi- Peak, and Average. However, with a modulated CW or broadband signal an
amplitude difference will be noted.
The modulation percentage of a modulated CW signal or the duty cycle of an impulsive
signal can be approximated by comparing the Peak and RMS levels. The Peak/RMS level can be
determined by subtracting the measured RMS level from the measured Peak level.
The power level in dBm (decibel referred to one milliwatt) into the 50

input of the EM-
2115 can be determined by subtracting 107 dB from the indicated meter reading (in dB(µV)).