2.11.0 OFF-THE-AIR MONITOR
The
1.5
microvolt sensitivity
of
the
Communications
Service Monitor receiver allows off-the-air monitoring
and measurement
of
transmitter frequency
error
and
deviation to 1000 MHz. A variable squelch allows weak
signals to be monitored, but can be set tighter to ensure
the
proper
signal-to-noise ratio for measurement accura-
cy.
The off-the-air monitor function enables frequent
parameter
checks without leaving the shop, thus spotting
system
degradation
early
and
keeping service costs
down. Bandwidth can be set
"WIDE"
for off-channel
signal location
or
wide band FM;
or
"NARROW"
for
maximum sensitivity and selectivity.
2.12.0
OFF-THE-AIR
PRIVATE
LINE
FREQUENCY
COUNTER
Identifies the PL frequency
of
any radio under test to
allow complete testing
of
PL subaudible tone signalling.
2.13.0 MULTIPURPOSE OSCILLOSCOPE
This general purpose scope
is
ideal for waveform analysis
in
two-way communication servicing. Use it for viewing
modulation signals (either internally
or
externally gener-
ated). detection
of
asymmetric modulation
or
audio dis-
tortion. and general purpose signal tracing and trou-
bleshooting.
2.14.0 MULTIMODE CODE SYNTHESIZER
The Communications Service Monitor generates PRI-
VATE
LINE
tones
(PL),
DIGITAL
PRIVATE
LINE
codes
(DPL),
two-tone sequential paging codes and
tone-remote signalling tones. All codes are available at
the
"MOD
OUT"
jack, as well as being used internally to
modulate the
RF
signal generator. This eliminates the
necessity
of
using separate generators and oscillators for
general servicing, setting transmitter deviation,
or
for
checking
tone
remote base control lines.
2.15.0 SIMULTANEOUS MODULATION
Modulation is simultaneously available from an internal
I KHz tone
generator,
a
multimode
code
synthesizer,
and from external inputs. The external modulation can
be voice from a standard Motorola mobile radio micro-
phone (which plugs into the front panel
of
the instru-
ment), as well as a signal applied to the external BNC
input. Separate controls are provided for independently
setting the levels
of
the
I
KHz
tone, the code synthesizer,
and the external modulation
sourc~s.
The
I KHz test
tone
is
a convenient source
of
modulation for making
SIN
AD
measurements. A
"MOD
OUT"
connector pro-
vides external access to all
of
the modulation signals.
2.16.0 DIGITAL/ANALOG VOLTMETER
The
built-in voltmeter provides circuit and power supply
service capability.
AC
voltage reading are RMS values.
2-2
2.17.0
SPECTRUM
ANALYZER
The R-2400 includes a spectrum analyzer which pro-
vides frequency spectrum display while allowing the
user
to
monitor the audio
of
the programmed frequency
signal. Three dispersions
of
I,
.1,
and
.01
MHz/div
are
available.
In
"Anlzr Sens Mon", the "Antenna"
port
is
used. The range
of
power levels displayed when the step
attenuator is in the 0 dB position
is
-40
dBm (top
graticule)
to
-100 dBm (noise floor). Vertical divisions
are
10
dB each. When
70
dB attenuation
is
added using
the step attenuator, the range
of
power levels displayed
becomes +
27
dBm
to
-30
dBm. Care must be taken
to
not exceed the maximum input level
of
.5
watt ( +
27
dBm)
at
the
Antenna
input. In "Anlzr
Pwr
Mon", the
RF
signal
that
is
applied to the
"RF
In/Out"
port
is
sampled
and
displayed. The required
amount
of
at-
tenuation
to
maintain
an
on-screen display can be ad-
justed with the step attenuator.
2.18.0
THE
FIRST
IN
A
SERIES/TWO-WAY
SERVICE
OPTION
The TWO-WAY SERVICE
OPTION
is
the first in a
series
of
new option cards. This
PC
board, plug in
compatible with any R-2200 (or R-2400) via
an
open
option module slot
and
comes equipped with the
following functions:
TWO-WAY SERVICE
OPTION
DPL
DECODE
DTMF
ENCODE
DTMF
DECODE
Some
of
the
major
features
of
the
DPL
Decoder in-
cludes OFF-THE-AIR decoding
of
DPL
or
IDPL
codes. The Two-Way Service Option will decode only
valid
DPL
codes
and
will not display invalid codes.
With the
DPL
encoder, standard in every R-2200 (or
R-2400), the service technician has a "failsafe opera-
tion"
making it easier
and
less time consuming when
performing a complete
DPL
system check.
The option card also provides multiple methods in which
to encode DTMF tones. The most basic form
of
generating
DTMF, a real time encoder, is one selection possible. There
are also encoding formats available for operator selection
which include:
1)
I6 digit storage (BATCH ENCODE), 2)
user programmable timing, and 3) simultaneous PL and
DTMF encode.
A last function
of
the Two-Way Option is DTMF Decode.
In this mode the service monitor will decode DTMF tones
OFF-THE-AIR or via the modulation input BNC connec-
tor. This option will decode and store
up
to I6 DTMF digits.
With
DPL,
DTMF
and
the standard
PL
Encode
and
Decode built-in, the R-2210
and
R-2410 Communica-
tions Service Monitors qualify as a complete signalling
simulator, capable
of
performing a complete signalling
system check
on
the land mobile industries most com-
mon
signalling formats.
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