OPERATION
2-16
September 2001
Part No. 001-5100-001
(cycling power does not reselect the old talk group).
Proceed as follows:
1. Select the channel to be changed and then press the
Talk Group Select option switch.
2. Display the talk group to be assigned to that channel
by pressing the
and
keys. Talk groups are
indicated by an alias (unique alphanumeric identifi-
cation).
3. To select that talk group and return to normal oper-
ation, press the Talk Group select switch again. If
talk group selection has been disabled on the chan-
nel by programming, the talk group does not change
and an error tone sounds.
Individual Calls
If the Individual Call option switch is
programmed and the radio is a full keypad (18-key)
mode, individual calls can be placed to a specific
mobile radio on Project 25 channels. This call differs
from standard group calls in that only one mobile
instead of entire groups of mobiles may receive the
call. To respond to an individual call, simply press the
PTT switch and begin talking before a call timer
expires. Proceed as follows to place this call:
1. Press the Individual Call option switch and the iden-
tification of the last individual call placed is dis-
played as IDxxxxxx.
2. If required, enter the ID of the mobile being called
using the keypad.
3. Press the PTT switch and begin talking.
When individual calls are received, the trans-
ceiver may be programmed to display the selected talk
group, the talk group of the call, or the ID of the
calling radio.
2.6.17 CONVENTIONAL SECURE
COMMUNICATION
Introduction
There are two different protocols that can be used
to provide secure communication on conventional
analog channels: SecureNet™ and 460 scrambling.
More information on these protocols follows.
SecureNet
SecureNet is a proprietary Motorola protocol that
digitizes the voice and then encrypts it using the DES
algorithm. It provides the highest level of security.
There are two DES protocols:
•
DES (CFB) uses cipher feedback DES encryption.
A disadvantage of this type is reduced communica-
tion range when compared to clear voice.
•
DES-XL uses counter addressing feedback DES. It
provides better range but at lower voice quality.
The transmission mode (DES or DES-XL) is
selected by the programming software for each
SecureNet analog channel. If a channel is programmed
for DES-XL, it will also receive DES, but transmis-
sions always occur in DES-XL.
Each SecureNet capable channel is assigned an
encryption number from 0-15. The key corresponding
to this number is loaded into the radio using the
Motorola key loader. There is a maximum of 16 keys
that can be loaded into the radio at one time.
Transmissions on an analog channel are in the
clear mode if the channel has been strapped to the
clear mode by programming, and in the SecureNet
mode if it has been strapped to SecureNet. If the
channel has been strapped to “switched”, the mode is
selected by the Clear/Secure option switch. When a
message is received or transmitted in the secure mode,
“
Sec
” is indicated in the upper part of the display.
If an attempt is made to transmit a secure
message without loading the corresponding key,
“KEYFAIL” is displayed. The message must then be
transmitted in the clear mode (this is possible only if
the channel is strapped to “switchable”) or the key
must be loaded.
460 Scrambling
The 460 Scrambling protocol is a proprietary
Transcrypt protocol that is compatible with the stand-
alone scrambling option from Transcrypt. If equipped
