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

(1)  For Ei  < 1 dB, Wi  = 0.

(2)  For 1 dB < Ei  < 12 dB, get Wi  from table VIII.

(3)  For 12 dB < Ei  < 36 dB, Wi  = (Ei  - 6)/30.

(4)  For Ei  > 36 dB, Wi  = 1.

The articulation index sample for each received ALE word shall be computed from measurements Wi  within each frequency band as follows.  The weighting factors Fi  shall be taken from the last column of table VII above:

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AI        Fi Wi

i  1

Articulation index samples shall be histogrammed as specified in 4.5.3.

NOTE:  The articulation index measurements are performed only over the 625 to 2625

Hz frequency range, but the articulation index value obtained is extrapolated to the entire voice range so that the range of articulation index values is 0 to 100 percent.

TABLE VIII.  Ei  to Wi  conversion (1 dB £Ei  £12 dB).

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