EF JOHNSON 5100 ES II, Operating Manual, Page: 128 / 144

10-6 5100 ES Model II/III Portable Radio Operating Manual December 2006
Secure Communication (Encryption)
Note
If all channels/talk groups are strapped clear or secure and no Clear/Secure option switch
or menu parameter is programmed, this parameter must always be selected (see
following).
If the Clear/Secure switch or menu parameter are not programmed, the radio is always in
the last known state (usually Clear) and there is no way to change it. For example, if the
last known state is Clear and this parameter is not selected, it is never possible to transmit
a Secure message on a channel strapped Secure. An error tone sounds.
10.3.2 Receive Mode Options
The following receive options can be programmed with conventional operation. With
SMARTNET/SmartZone and P25 Trunked operation, encrypted calls are received if the
proper key is programmed.
No Autodetect - Only signals coded like the transmit signals are received.
Secure Autodetect - Both clear and secure signals are automatically detected. This
mode is automatically selected if the transmit mode is switch selectable.
Proper Key Autodetect
Analog Channels - When this feature is disabled and a message is received with the
wrong key, the audio unmutes and garbled (encrypted) audio is heard. However, if
this occurs with this feature enabled, the audio remains muted.
10.3.3 Talk Group Encryption Override
On conventional digital (P25) channels, the encryption strapping mode and PID are
programmed on a per talk group basis similar to the trunked modes (SMARTNET/
SmartZone/P25 Trunked). However, with this mode only, there is the option to override
the talk group encryption programming and program it on a per channel basis. Therefore,
if desired on conventional digital channels, encryption can be programmed differently for
each channel. Conventional analog channel encryption is always programmed on a per
channel basis.
10.4 OTAR (Over-The-Air Rekeying)
OTAR stands for “Over-The Air-Rekeying”. This is the process of sending encryption
keys and related key management messages over-the-air to specific radios. The advantage
of OTAR is that it allows these keys to be quickly and conveniently updated when
necessary. It is no longer necessary to periodically travel to the radio location or bring the
radio into a maintenance facility to load new keys.