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

e.  The mean error-free interval shall be evaluated indirectly.  ALE word errors detected by the Golay decoder and the ALE protocol shall be accumulated to estimate word-error and word-error-burst probabilities; these probabilities shall then be used to estimate error-free interval in accordance with 5.5.1.4.

4.5.2  Link performance measures.

The link performance measures for ALQA are standardized as follows:

a.  Achievable voice quality samples shall combine SINAD measurements (DO:  articulation index measurements) with channel occupancy to produce a histogram of the voice quality of the best channel available during each scan of the channels by the ALE controller, in accordance with 5.5.2.1.

b.  Data link performance shall be gauged using available data capacity in accordance with

5.5.2.2.  Available data capacity samples measure the effective data rate available to each station, including the effects of retransmissions due to channel errors, and contention for transmission facilities from other traffic.

NOTE:  Achievable voice quality and available data capacity are optional; implementations shall comply with the applicable sections of 5.5.2.

4.5.3  ALQA histogramming.

Measurements of SINAD, PBER, articulation index, spectral distortion, achievable voice quality, and available data capacity shall be accumulated for ALQA use as described below.

4.5.3.1  Exceedance distributions.

An "exceedance distribution" QX(x) is related to the cumulative probability distribution function

PX(x):

Qx(X) = Pr[X > X] = 1 - Px(X).

Exceedance distributions for the channel quality measures and link performance measures listed in

4.5.3 shall be estimated by first histogramming samples of these measures, and then averaging the histograms over the integrating periods specified in 4.5.3.2.  A history of these histograms shall be retained for use when no current data is available.

4.5.3.2  Integrating periods.

a.  Four distinct time epochs shall be used for accumulating the histogram data.  Within each epoch k, Nk  histograms shall be accumulated and averaged, each containing measurements over a period of tk.  Epoch 1 represents the short term for the HF channel.  Because the values defined in the channel quality measure descriptions above are intended to provide

short-term granularity on the HF channel on the order of 1 minute, t1  = 60 seconds.  Since 15 minutes represents a time interval over which the statistics of the nominal HF channel may be

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