Automatic Link Establishment Flashcards
Automatic link establishment is the worldwide standard for what ?
For digitally initiating and sustaining HF radio communications
What is the purpose of automatic link establishment?
To provide a reliable, rapid method of calling and connecting HF communications
What does a automatic link establishment radio consist of ?
An HF single side band radio transceiver
An internal microprocessor
A MFSK modem
It also has an unique ALE address
What does an automatic link establishment system do when it is not actively in contact with another system ?
The HF SSB transceiver scans through a list of HF frequencies listening for any other ALE signals
What is BER
Bit error rate
What is the bit error rate used for ?
To store a quality score for frequencies and sender addresses that other stations have used
What is the bit error rate
It is a measure of signal quality.
What is an error in telecommunications ?
It is the ratio of the number of bits, elements, characters or blocks incorrectly received to the number sent during a specific time interval
How does an automatic link establishment reach a specific station ?
The called enters the ALE address,
The selects the best available idle channel for that destination address
Then sends a selective calling signal identifying the recipient
What is selective calling ? Or SELCAL
It is similar to a locked door. Selective calling locks out any signal unless it has the correct key ( a specific digital code )
If a radio has carrier squelch unlocked, what will happen ?
It will allow any signal in
What happens when a automatic link establishment system detects ALE activity ?
It will stop scanning and stay on that channel to confirm if the call is for itself or someone else
What happens if an ALE station detects a call for itself?
The two stations will automatically handshake to confirm the link is sufficient quality.
It will then notify the operators
What happens upon a successful link of two ALE stations ?
The receiving station generally emits an audible alarm and shows a visual alert to the operator.
It will also indicated the incoming call sign
What are some common applications ALE provides ?
Voice conversation Alerting Data exchange Texting Instant messaging Email File transfer Image Telemetry Geo position tracking
What has ALE diminished the need for ?
Pre determined time schedules or monitoring static
Prediction charts, propagation beacons
Chirp sounder
propagation prediction software
Radio operator guess work
What is ALE most commonly used for ?
Hooking up operators for voice contacts on SSB
HF internet connectivity for email SMS phone texting Real time chat via HF text Geo positioning reporting File transfer
Who uses ALE systems ?
Emergency and disaster relief agencies
Military
Guard forces
Specifically Red Cross
NATO
Disaster medical assistance teams
