General Dynamics R2600 Series, Operator'S Manual, Page: 207 / 402

Section 12
SECURENET DESCRIPTION
12-1 INTRODUCTION
The SECURENET Option extends the standard
functions of the R2670 to provide an all-in-one
servicing instrument for communications
equipment that uses SECURENET voice
protection.
12-2 BASIC OPERATION
The R2670 with SECURENET Option can emulate
the same digital environment used by
SECURENET radios in private mode. This
capability allows the analyzer to interoperate with
conventional SECURENET user equipment.
Standard test equipment is unable to decipher
private audio transmissions from SECURENET
radios because the audio signals are converted from
their native analog format to a digital, ciphered
representation prior to transmission.
Some radios in the SECURENET system have both
clear and privacy modes available. When operated
in privacy mode, the radio scrambles
communications prior to their transmission. Only
intended subscribers, with compatible hardware
plus matching security keys, can decipher the
message. In this way, users of a system can be
partitioned into groups, each with their own
security key. The R2670 with SECURENET
Option will accept an external operating key from
any compatible key loader. Alternately, the user
can select one of the Option's own internal test keys
to program the radio under test.
In its SECURENET mode, the R2670 provides
display screens for monitoring bit error rate
characteristics of a radio under test and also
generates bit error rate test patterns to support this
mode of operation.
The R2670 with SECURENET Option provides a
clear scope display of baseband signals as either the
input to the vocoder (generate mode) or the output
from the vocoder (monitor mode).
12-3 TEST CONSIDERATIONS
Systems using encrypted communications have a
need to maintain even higher standards on RF
signal quality than normal FM radio systems.
Encryption subjects the SECURENET signals to
additional processing. In order to work reliably, the
radios must be tuned to preserve critical factors
such as operating frequency response and
transmitter deviation. Individual test meters and
generators compound the effects of multiple RF
paths and wirelines in the test environment,
resulting in degraded signals and less accurate
measurements.
Operating in secure or standard mode, the R2670
with SECURENET Option bundles a wide
assortment of sophisticated test features in a single
instrument.
12-4 SPECIAL TERMS
The following list contains brief definitions of
special terms that are used in association with
SECURENET radios and test equipment:
Algorithm - In secure systems, an algorithm is a
distinct method for translating clear information
(input) to a secure version of the information
(output). The same algorithm is used to interpret
the message. SECURENET systems use the
following algorithms:

DVP and DVP-XL

DES and DES-XL

DVI-XL
161