EF JOHNSON 5100 ES II, Operating Manual

Page: 126 / 144

10-4 5100 ES Model II/III Portable Radio Operating Manual December 2006
Secure Communication (Encryption)
Number), typically from 0-4095. A Keys Table must then be programmed to link
channel PIDs to a specific SLN.
The use of this type of indirect linking allows keysets and key IDs to be changed via
OTAR while keeping the mapping from the channel or talk group the same. For
example, as shown in Figure 10.1, PID 4 selects SLN 24 which selects key slot 24 in
both keysets. This slot contains Key ID 69 in Keyset 1 and Key ID 91 in Keyset 2. Only
one keyset is active at a time. The actual key chosen between these two to transmit with
will depend on which keyset is active, Keyset 1 or Keyset2.
10.2.3 Maintaining Keys in Memory
The radio may need to be connected to a constant power source to preserve the encryption
keys in memory. The programming of the Infinite Key Retention parameter determines if
keys are permanently stored in memory or erased soon after power is removed.
When Infinite Key Retention is enabled, keys are stored in memory and are not lost when
power is removed. If it is disabled, they are maintained only until the storage capacitance
discharges. With 5100 ES models, storage capacitors maintain the supply voltage (and
encryption keys) for approximately 30 seconds without power applied. Therefore, when
changing the battery, make sure to reattach another within 30 seconds.
10.2.4 Encryption Key Select
Note
This feature is available on conventional channels only.
When multiple encryption keys are programmed (see preceding information), the Key
Select option switch can be programmed to allow selection of another key for the current
channel. This feature changes the PID (hardware location) of the key, and the change is
permanent (cycling power or selecting a different channel does not reselect the original
key). Therefore, to switch back to the original key, it must be manually reselected. Proceed
as follows to select a key:
1
Press the Key Select switch or select that menu parameter.
2
Press the Up/Down switch to display the desired key and then press the < F2 > (Select)
key to select it. Press the Key Select switch again to return the display to normal
operation.