TETRA Question

[jacobsmith]

Does TETRA use "NAC" I'm sure it's not called this on TETRA but do they use special codes to mute other traffic on DMO mode? If so, what are the codes like? ex: FKF, 123.. thanks.

[Raccon]

Originally Posted by jacobsmith

Does TETRA use "NAC" I'm sure it's not called this on TETRA but do they use special codes to mute other traffic on DMO mode? If so, what are the codes like? ex: FKF, 123.. thanks.

In TETRA DMO you can associate each channel (= frequency) with a GSSI - Group Short Subscriber Identity, so that a radio without the matching GSSI will not be able to listen to the communication.
Since it would be possible to program the channel and GSSI to any TETRA radio (assuming you have the required knowledge and tools) encryption can be applied by associating a SCK - Static Cypher Key with each DMO channel/GSSI, preventing eaves-dropping.

[denseglow]

Originally Posted by Raccon

In TETRA DMO you can associate each channel (= frequency) with a GSSI - Group Short Subscriber Identity, so that a radio without the matching GSSI will not be able to listen to the communication.
Since it would be possible to program the channel and GSSI to any TETRA radio (assuming you have the required knowledge and tools) encryption can be applied by associating a SCK - Static Cypher Key with each DMO channel/GSSI, preventing eaves-dropping.

May I ask? Is this a three digit code, 5, 20? Can you use a combination of letters and numbers or just one or the other? Is there a limit to how many numbers you have in a code, ect? I am trying to learn more aboout TETRA and since we don't have it here in the states this is my only way to!

Thanks!

[Raccon]

Originally Posted by denseglow

May I ask? Is this a three digit code, 5, 20? Can you use a combination of letters and numbers or just one or the other? Is there a limit to how many numbers you have in a code, ect? I am trying to learn more aboout TETRA and since we don't have it here in the states this is my only way to!

Thanks!

The GSSI can be in the range from 0 to 9999999 while the SCK is a 80-bit key (typically entered in HEX, e.g. 01 A4 FE 65 ...).

A TETRA radio can store at least one set containing 32 SCKs, each of which can be associated with any of the DMO groups; actually keys 1-30 are recommended for DMO use and keys 31 & 32 for fallback operation of the base station but as mentioned it's only a recommendation.