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Digital Radio Testing
Hysteresis
M-Curve
Measurement
Note
Equipment Setup
Note
1-26
The Hysteresis M-Curve measurement uses the same
parameters and setup as the Static M-Curve Test.
1. The basic setup for all measurements involves
interrupting the IF path of the digital radio with a
fading simulator. If a Bit Error Rate Tester (BERT)
is used, connect the appropriate data channels. In the
gure below, the DS3 data out from the BERT is
connected to the DS3 input of the transmitter, and
the BASEBAND output of the receiver to the DS3
data input of the BERT. The ERROR OUTPUT
of the BERT is connected to the ERROR PULSE
INPUT of the Fader. This input can be set to match
the impedance of the BERT.
Some digital radios have their own error outputs and
internal data checking schemes that limit the need for
a BERT. See the manual for your radio if you wish
to connect the ERROR PULSE INPUT of the Fader
directly to the radio. There may be a connection that
must be made between two ports of the radio system for
this to work.
2. The RF output of the transmitter is connected to the
RF input of the receiver. Appropriate attenuation is
used to protect the RF input of the receiver. Check
the manual of the receiver and the transmitter to
insure safe levels for the receiver input.
3. The Alarm Output on the receiver can be connected
to the Alarm Input on the Fader. This connection is
only needed for recovery tests, and tests where no
HP 11757B
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