Automatic Link Establishment (ALE)

The traditional method of operating HF communication systems requires manual frequency-time planning and coordination in addition to skilled radio operators who are needed to perform the frequency selection, frequency monitoring, and link establishment. The HF Radio Set, operating under the control of ALE, will provide automated selective calling, preset channel scanning, and real time channel propagation evaluation to achieve automatic connectivity.

The automatic connectivity of ALE provides improved HF communications reliability with less user training, including: automatic frequency management, automatic link establishment, automatic link confirmation, and automatic disconnect. ALE improves the connectivity between communication systems by monitoring multiple frequencies and selecting the best calling frequency. This selection is based on real time analysis of the quality of the frequency channel. If desired, the ALE system can operate in a “radio silent” mode, which allows the channel quality to be continuously updated, but which prevents transmissions from the system except by operator intervention.

The sequence of events in an ALE call may be summarized as follows:

The operator selects an individual address to call and then keys the system. The system then automatically;

1. Selects the best preset channel
2. Determines the availability of selected channel
3. Transmits the address data sequence
4. Receives the automatic handshake - link confirmation
5. Breaks the squelch
6. Signals the user to begin communications
7. Monitors system key activity
8. Returns the system to the muted scan mode when communications are completed

The basis for ALE frequency selection is the Link Quality Analysis (LQA) that is continuously performed on the channels within the ALE scan list. The LQA is determined by analyzing the? HF Products Collins HF Features signal characteristics (signal-to-noise ratio and delay distortion) of the data signal used in sounding or initiating an ALE call. A database of the LQA values is generated, which ranks the quality of the ALE frequencies associated with each of the addressee’s mission directories. The entries in the LQA database are continually updated, with automatic downgrading of old entries.

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