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Operating Instruction
ERO•SCAN
®
Screening and Diagnostic Version
operating_instructions_8106556-6_EROSCAN_e_15a 59 8106556-5 02/15
lower the noise floor of the test. In order to reduce the possibility of obtaining an artificially
low noise floor, the minimum threshold level is limited.
Comment about Variations in the SNR Estimate
The user needs to be aware that the SNR estimate has an inherent statistical variation due to
the effects of random noise, especially when no emission is actually present. If a test is
performed with the instrument’s probe placed in a test cavity, it can be shown theoretically
that the SNR will be greater than 6 dB approximately 7 times out of 100. This is not a
limitation of the instrument, but a fundamental property of the method used to estimate
the SNR in all emission testing. In order to reduce the occurrence of this “false” emission,
the instrument limits the minimum value of NF, which has the effect of reducing the SNR for
tests that have a low noise floor. As the noise level of the test increases, the user will notice
that more “false” emissions will appear, which is to be expected.