Section 19
PROJECT 25 INTRODUCTION
19-1 INTRODUCTION
This manual contains information regarding the
R2670 Project 25 features. Project 25 provides
unique testing features for communications
equipment using Project 25 encoding and
modulation principles. The additional Project 25
test capabilities are accessed via the LCD display,
screen-defined softkeys, numeric keypad, cursor
movement keys, and optical tuning knob. Some
of the Project 25 functions may also be accessed
via the remote control interface port.
19-2 CAPABILITIES
The Project 25 feature set gives the R2670 the
capability of monitoring and generating Project
25 signals. A Project 25 signal relates to the
Association of Public-Safety Communications
Officials International (APCO) Project 25 digital
standard Common Air Interface (CAI) signaling
scheme in which a serial bit stream is encoded,
mapped into one of four corresponding
amplitudes, filtered digitally, and then modulated
onto an RF carrier.
NOTE
Trunking operation is described in section 23.
Voice Mode System Testing
Voice mode provides Project 25-compatible
modulation and demodulation with Improved
Multi-Band Excitation (IMBE) vocoding. The
Project 25 Option generate and monitor modes
support actual functional voice testing in both
the unencrypted and encrypted modes. In the
encrypted mode, either a test key or an operator
key loaded from a separate compatible
keyloader can be used.
Bit Error Rate (BER) Testing
A BER test pattern can be selected to modulate
the R2670 generator for BER testing. A 1011
Hz Tone Test pattern can likewise be decoded
by the R2670 in monitor mode and a BER
computed from a comparison with a stored
version of the expected pattern.
Dedicated Test Screens
Dedicated Project 25 test screens are zoned
with RF and Modulation control screens to
simultaneously display test results along with
their test conditions. Dedicated test screens
can be set up as a start-up default condition or
as a programmable test set-up.
Clear Scope Display
The display provides a graphic image of the
audio clear signal. This clear signal is
selectable at either the vocoder input in
generate mode or the vocoder output in
monitor mode.
19-3 PROJECT 25 CONNECTORS
The R2670 has two connectors as shown in
Figure 19-1. Both connectors are located on the
side of the housing. The KVL conne
ctor provides
a receptacle for loading an external encryption
key. The other connector is an interface port.
253
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