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

discussed below). If a date and time DATA word and a frequency-designating DATA word are both sent following the CMD, the date and time word shall be sent first.

b. A frequency other than that carrying the CMD may be designated by placing a frequency designator (see 5.3) in ALE word bits W5-24 of a DATA word. Bit W4 of the DATA word shall be set to "O" to indicate a positive frequency offset or to 1 to indicate a negative frequency offset from the frequency carrying the CMD.

5.6.6.8 Poll operator (default NAK).

An ALE controller receiving this CMD shall prompt the operator to manually acknowledge the transmission. If the operator acknowledges the prompt, the ALE controller shall reply to this CMD with a transmission terminating in TWAS and return to scan. Otherwise (either no operator response by time "T", or a request for negative acknowledgment), the ALE controller shall respond with a transmission terminating in TIS (and continue to listen for transmissions from the calling station until returned to scan by the operator or by the wait for activity timer).

5.6.6.9 Request operator ACK.

An ALE controller receiving this CMD shall prompt the operator to manually acknowledge the transmission. If the operator acknowledges the prompt, the ALE controller shall reply to this CMD with a transmission terminating in TWAS and return to scan. If the operator requests a negative acknowledgment, the ALE controller shall respond with a transmission terminating in TIS and continue to listen for transmissions from the calling station until returned to scan by the operator or by the wait for activity timer. If no operator response is received by time "T", the ALE controller shall not respond, and shall immediately return to scan.

5.6.6.1O Schedule periodic function.

When received immediately after another scheduling CMD from 5.6.6, this CMD shall cause that CMD to be executed repeatedly as specified by the time offset field in this CMD. If TB1-7 are all l's (date and time option), the preceding CMD shall be executed daily at the time specified in a date and time DATA word that follows this CMD, starting on the day indicted in that DATA word. If the date and time option is not used, the preceding CMD shall be repeated at the interval given in the time offset field.

5.6.6.11 Quiet Contact.

A station receiving this CMD is requested to listen for a call from the station sending the CMD at the designated time "T" if the time offset field is not all 1's, otherwise at the date and time in the DATA word that immediately follows the CMD. The call will be placed on the channel carrying the CMD, unless another frequency is specified in a DATA word (formatted as in 5.6.6.7). If a date and time DATA word and a frequency-designating DATA word are both sent following the CMD, the date and time word shall be sent first.

5.6.6.12 Respond and wait.