Oscilloscope Displays; Features; Self Testing; 22.7 .3 Dual Code Operation - Motorola R-20010 Maintenance Manual

represents negative deviation. By observing the bar
graphs' swing about 4.0 kHz, the operator can get a
qualitative measure of how the system is performing.
A digital readout on the display indicates an averaged
deviation value for a quantitative measurement.
Transmitted deviation can be adjusted with the RF
scan knob on the R2004/5D.
22.6.3 LINE LEVEL MEASUREMENT
The R2004/5D offers balanced and single-ended line
inputs and outputs for interfacing with twisted pair
systems and modems. To measure the voltage level
output and the voltage level input, a line level display
is incorporated into the Secure Com test system. The
display contains two bar graphs, one for line level out
and one for line level in. Both bar graphs are continu-
ously active. The line voltage is measured in terms of
AC voltage only. No power measurements are made.
The output voltage level is adjusted with the RF scan
control on the front panel of the Secure Com tester.
22.6.4 OSCILLOSCOPE DISPLAYS
To aid the service operator, the Secure Com tester
provides oscilloscope displays of intermediate points
in the encryption and decryption process. These inter-
mediate points are as follows:
• the transmitted eye pattern (GEN EYE)
• the audio that is being encrypted (GEN AUDIO)
• the received eye pattern (MON EYE)
• the received audio after being decoded (MON
AUDIO) .
Depending on whether the R2004/5D is in RF or
AUDIO mode, the MON EYE and GEN EYE displays
show waveforms from different parts of the circuitry.
RFMODE:
When the R2004/5D is configured for RF mode, the
GEN EYE and MON EYE displays take their infor-
mation from the same place as the modulation screen
in the standard R2001D. This is done because the
MON EYE and GEN EYE screens are calibrated in
order that deviation can be read directly off the oscil-
loscope screen. Internally, the MON EYE and GEN
EYE display the waveforms from the modulation
screen in the R2001D. Consequently, the generate/
monitor switch on the front panel determines the
waveform that will be displayed. For example, if the
GEN EYE screen were selected, and the R2004/5D was
already in monitor (receive) mode, the received eye
pattern would be displayed instead of the transmitted
eye pattern. To avoid operator confusion as to which
waveform is being displayed, the Secure Com tester
displays a ground line when the oscilloscope display
selected does not correspond to the position of the
generate/monitor switch.
AUDIO MODE:
When the R2004/5D has been set up for audio mode,
the MON EYE and GEN EYE screens show the
encrypted eye pattern as it is being output by the line
drivers and received by the line receivers. The oscil-
loscope displays are calibrated so that voltage mea-
surements can be made directly off the screen. The
MON AUDIO and GEN AUDIO are the same displays
regardless of the current mode of the R2004/5D. Both
of these displays are scaled to reflect the actual volt-
ages being input to the encoder section and being out-
put by the decoder section.
22.7 FEATURES
22.7.1 END OF MESSAGE (EOM SIGNALING
TEST)
Motorola encrypted radios transmit a burst of a 6.0
kHz sine wave at the end of a transmission to notify
the receiving unit that the transmission is complete
and that squelch should be applied. This is done to
avoid "squelch
tails".
The Secure Com tester offers test
capability of this signaling function by generating a
continuous EOM and by detecting a received EOM.
22.7.2 SELF TESTING
The Secure Com tester performs basic tests on itself.
Upon powerup, a self test is performed wherein the
random access memory (RAM) and the read only
memory (ROM), in both the standard R2001D circuits
and the Secure Com circuits is checked. The RAM is
tested by writing certain test patterns and then veri-
fying them. ROM is tested by calculating the check-
sum and comparing it with the value stored in a
particular location in the ROM. Another self test which
can be performed
is
a test of the internal encoder and
decoder. When the self test is selected by the operator,
a 2.0 kHz tone is directly injected into the encoder. The
encoder's output is looped to the decoder, and if the
system is functioning properly, the 2.0 kHz tone
will
be heard through R2004/5D speaker.
22.7 .3 DUAL CODE OPERATION
There are some Motorola radios encrypted with
DVP (Securenet), which have a dual code feature. With
dual code radios, another code key can be generated
from the one which was programmed by throwing the
switch on the radio. The dual code feature is only
available with the Securenet encryption algorithm.
Dual code operation can be tested with the R2004/5D.
The Secure Com tester has a code selection which can
only be made when operating with the Securenet for-
mat.
22-2A