MIL-STD-187-721 Interoperability And Performance Standard For Advanced Adaptive Hf RadioThe purpose of this document is to describe the technical parameters for adaptive high frequency HF radio that are more advanced than those described in MIL-STD-188-141. The advanced technology contained in this standard will guide the planning of military adaptive HF radio network technology into the 21st century. To fully understand and utilize this document, it is necessary to refer to portions of MIL-STD-188-141.

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MIL-STD-187-721D

5.11.1.1 HFDLP ALM No Operational (No Op) CMD.

The No Op CMD shall be sent when no other CMD is appropriate. No arguments are needed. The argument bits shall all be set to 0.

5.11.1.2 HFDLP ALM Preferred Channels CMD.

The Preferred Channels CMD shall be sent to indicate alternative traffic channels for use when changing frequencies from the current channel. One or more 5-bit channel numbers shall be sent as arguments to this CMD (see figure 25). The channel number in the most-significant bits of the Arguments field is the most preferred alternative channel, with other channels listed in descending order of preference. When fewer than six channels are specified, the least-preferred channel number shall be repeated as required to fill the arguments field.

2 6 7 7 per chan nel number

000001

Ch #

(more ch numbers as needed)

FIGURE 25. HFDLP ALM preferred channels CMD.

5.11.1.3 HFDLP ALM assign frequency CMD.

The Assign Frequency CMD shall be sent to assign a frequency to a channel number as shown on figure 26.

2 6 3 7 32

000010

Flags

Ch #

BCD: 100 MHz 10 MHz 1 MHz 100 kHz 10 kHz 1 kHz 100 Hz 10 Hz

FIGURE 26. HFDLP ALM assign frequency CMD.

The Flags field shall indicate whether the specified frequency is absolute or relative to the frequency currently in use to carry traffic to the station sending the CMD (see table XXI).

TABLE XXI. Flags in HFDLP ALM frequency CMDs.

Flags Meaning of Frequency Field

000 (reserved)

001 Absolute frequency

010 Negative offset from current frequency

011 Positive offset from current frequency

1xx (reserved)

The frequency (or frequency offset) shall be represented in binary coded decimal (BCD), 4 bits per digit, with digits for 100, 10, and 1 MHz; 100, 10, and 1 kHz, and 100 and 10 Hz.