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Rack-Mount RDMS
TM
Telemetry Receiver
160
Quasonix, Inc.
The BERT can be enabled, but not running, in the case of a time, bit, or error count limit.
An asterisk '*' after the error rate column indicates that the data is inverted. If the display is continuous and a time,
bit, or error limit is set with repeating gating, the display shows the end of the test by displaying '>>>' in the first
three columns.
The following shows an example display with a five (5) second repeating test.
E R Time Bit Count Error Count Error Rate
# ! 0:00:00:03.772 3.773e+07 2 5.301e-08*
# ! 0:00:00:04.023 4.023e+07 2 4.971e-08*
# ! 0:00:00:04.276 4.276e+07 2 4.677e-08*
# ! 0:00:00:04.527 4.528e+07 2 4.417e-08*
# ! 0:00:00:04.779 4.780e+07 2 4.184e-08*
>>> 0:00:00:05.000 5.000e+07 2 4.000e-08*
# ! 0:00:00:00.251 2.512e+06 0 0.000e+00*
# ! 0:00:00:00.503 5.032e+06 0 0.000e+00*
# ! 0:00:00:00.757 7.574e+06 2 2.641e-07*
# ! 0:00:00:01.011 1.011e+07 2 1.978e-07*
# ! 0:00:00:01.263 1.264e+07 2 1.582e-07*
9.1 Test Noise Commands
Digitally generated additive white Gaussian noise (AWGN) can be injected in the demodulator for test purposes.
This noise can exhaust most or all of the demodulator's error-free signal processing margin so that small
imperfections in the received signal will be visible as an increase in the bit error rate.
The noise level is calibrated relative to an extremely accurate measurement of the input signal level. This
measurement will be most accurate when the received signal has a high signal-to-noise ratio. Therefore, input signal
levels above -70 dBm are generally recommended. Due to the available dynamic range of the demodulator signal
processing path and the faithful representation of the AWGN, noise samples may be clipped, especially at or below
0 dB Eb/N0.
Note that the noise is injected following downconversion to baseband but before demodulation. Therefore, the noise
will affect demodulator output signals, including video outputs and the front panel display (eye diagram or
constellation), but it will not change measurements of the input signal (signal strength and signal quality).