Tyco Electronics MM23772 - Manual (Page 91)

MM23772, Rev. B
91
9.17.3 Private Mode
The Private Mode allows the radio to transmit encrypted messages and receive clear or private
transmissions. The radio transmits private if the group/channel is programmed for private operation and
forced operation is pre-programmed. If autoselect operation is pre-programmed and the radio is in the
Private Mode, the radio transmits in the mode of the received call if the hang time is active. If no hang
time is active, the radio transmits private.
Cryptographic keys are transferred to the radio using a cryptographic Keyloader. Up to seven (7) different
cryptographic keys, numbered 1-7, can be transferred from a Keyloader and stored in the radio. An
individual key is automatically selected on a per-group/channel basis according to the radio programming.
Groups and channels within the digital system can be programmed for keys 1-7 (private). Up to 8 banks
of 7 keys can be stored for private systems. The bank is specified per system.
When operating on a group or channel programmed for Private Mode, all transmissions are private
transmissions and the radio receives clear and private signals. The status icon is displayed when the
Private Mode is enabled. If the selected group or channel is programmed for auto-select capability, the
mode may be toggled between private and clear with the

key, then following the selection mode rules.
Radios programmed for forced private operation do not allow a change of the transmit mode.
9.17.3.1 Displaying the Currently Used Cryptographic Key Number
To Display the Currently Used Cryptographic Key Number for either the system encryption key (for
special call such as individual, phone, all, agency or fleet) or the group/channel key (for group or
conventional calls), perform the following procedure:
1. Press the  button.
2. Use the  or  button to select "DISP KEY."
3. Use the  or  button to toggle between displaying the system key (Figure 9-8) or the
group/channel key (Figure 9-9).
Figure 9-8: System Encryption Key Display
Figure 9-9: Group/Channel Encryption Key Display
9.17.3.2 Key Zero
All cryptographic keys can be zeroed (erased from radio memory) by pressing the  button and while
still pressing this button, press and hold the OPTION button. Press both buttons for 2 seconds. A series of
beeps will begin at the start of the 2 second period and then switch to a solid tone after the keys have been
zeroed. The display will indicate
KEY ZERO .