FREQUENCY HOPPING (FH) COMMUNICATIONS

TM 11-5820-890-10-8

FREQUENCY HOPPING (FH) COMMUNICATIONS

4.3.

Capabilities

4.3a.

In the frequency hopping (FH) mode of operation, the SINCGARS radio

FREQUENCIES

transmits and receives on any or all of the 2320 frequencies, with 25

KHz separation, in the 30.000 to 87.975 MHz range. For best results,

1200 or more of the total 2320 frequencies are normally used.

In the FH mode, the SINCGARS radio uses, "hops on," over 100

HOPPING

frequencies per second.

For two or more radios operating in the FH mode to communicate, it is

COMMUNICATING

essential that they contain the same set of frequencies and other

variables, commonly referred to as "FH Data".

Frequency Hopping (FH) Data

4.3b.

Frequencies made available for a SINCGARS radio to hop on are called

HOPSET

a "Hopset." A typical hopset consists of what remains of the total 2320

frequencies after protected frequencies, such as commercial

television, are removed. Protected frequencies are frequently referred

to as "Lockouts." In any case, except for technical purposes, lockouts

are treated as an integral part of the hopset.

The pattern in which the radio selects frequencies to hop on is

TSK

pseudo-random, as determined by the transmission security key

(TSK). Depending upon the number of frequencies available for

hopping and the TSK itself, the exact sequence of frequencies used

during any one second will not be repeated for long periods of time.

The remaining variable required for two or more frequency hopping

NET ID

radios to communicate is called the "Net ID." It is a three-digit number,

000-999, which controls where in the pseudo-random sequence the

radio begins to hop.

In shot-t, the term FH Data refers to:

Hopsets (with Lockouts

FH DATA

integrated), TSK, and Net ID.

Typically, division-sized units use the same Hopset and TSK for all

COMMONALITY

their SINCGARS frequency hopping nets. On the other hand, each net

is assigned its own Net ID.

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