Motorola MICOM-2TS Dokumentacja Pobierz pdf (Strona 87)

MICOM-2E-ALE Owner’s Manual

LQA Memory

The ALE builds a database of connectivity information based on calls

and digital ALE “sounding” messages transmitted by other stations in

the network. This information is stored in a special “LQA memory” and

used to determine the link quality of all channels in the networks. The

data in LQA memory is “time-weighted”, that is, recent information is

given more value than old, thus compensating for changing propagation

conditions.

Automatic Sounding

Automatic sounding is a method for testing the selected channels and

the propagation path under field conditions. The sounding signal is a

very short (beacon-like), unilateral identifying broadcast, carried out in

periodic intervals on unoccupied channels.

Identifying the sounding signal sent from a station indicates a high

probability of bilateral connectivity.

Long or short sounding cycles are mainly determined according to

propagation conditions. In case of slow propagation changes, long

intervals of about 1 or 2 hours may be sufficient. If, however, the

propagation changes are erratic and rapidly changing, or if the

connectivity information is critical, then shorter intervals are

recommended. Each station may also measure BER and S/N, and

update the LQA table accordingly.

NOTE

The maximum score for receiving an optimum

sounding is 70%; the minimum score is 30%. The

score given to a station that did not send any sounding

or a station whose sounding has not been received is

also 30%.

Sounding Cycle Time

The sounding messages is repeated at regular intervals on all channels

in the network. A complete round of sounding messges, or “sounding

cycle,” can be programmed to 30, 60, 90, or 120 minutes when the

automatic sounding is on. The sounding can be initiated manually when

there is a specific need for it, even if the system is set to operate in the

automatic mode.

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Motorola MICOM-2TS Dokumentacja Strona 87