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NOTE: The method of access to a Telecommunications Network Operator is not limited to landline connections and may be by means of optical fibre, microwave radio or by mobile cellular or personal communications networks.
6.4 Interface to Voice / Data Recording Equipment
The VCCS shall provide all the necessary signals and information to the Voice / Data Recording Equipment in compliance with Article 206 of the Air Navigation Order (1147).
7 System Performance
7.1 The clarity and volume of communications is to be 'readable' or 'perfectly readable' (see MATS Part 1) (1148).
7.2 Voice Transmission Quality – Radio Transmissions
7.2.1 The voice transmission quality of those communications facilities that utilise radio transmissions, the Aeronautical Mobile Service and the Surface Movement Control Service, shall meet or exceed a quality defined by the following:
a) The frequency response shall be such that the gain at any frequency between 300Hz and 3.4 kHz shall be within ± 3dB of the gain at 1kHz (1149).
b) The Total Harmonic Distortion (THD) shall not exceed 2% at any frequency between 300Hz and 3.4kHz with any gain controls adjusted to give the maximum permitted audio level at the headset or handset (1150).
c) Residual noise and hum on any correctly terminated idle voice circuit shall not exceed -60dBm (1151).
NOTE 1:The minimum voice channel audio frequency bandwidth for Air-Ground Communications using VHF Aeronautical Mobile radio frequencies has been determined as 400 Hz to 2.7 kHz for 25 kHz channel spacing.
NOTE 2:The voice transmission quality requirements apply to the voice channel only and do not include microphone and headset characteristics.
7.3 Voice Transmission Quality – Non-Radio Transmissions
7.3.1 The voice transmission quality of non-radio transmissions, shall meet or exceed those requirements as may be defined in standards for systems which are connected to the Public Switched Telephone Network (1152).
7.3.2 In the absence of any such standards referred to in 7.3.1, the following shall be met:
a) The frequency response shall be such that the gain at any frequency between 300Hz and 3.4 kHz shall be within ± 3dB of the gain at 1kHz (1153).
b) The Total Harmonic Distortion (THD) shall not exceed 2% at any frequency between 300Hz and 3.4kHz with any gain controls adjusted to give the maximum permitted audio level at the headset or handset (1154).
c) The Crosstalk level on any voice circuit shall not exceed -60dBm when a 1kHz tone is injected into any other circuit at a level of 10dB above nominal test tone level, with all voice circuits correctly terminated (1155).
d) Residual noise and hum on any correctly terminated idle voice circuit shall not exceed -60dBm (1156).
NOTE: The voice transmission quality requirements apply to the voice channel only and do not include microphone and headset characteristics.
COM 04 ATC Datalinks
Part 1 Preliminary Material
1 Introduction
Datalink applications have been available globally for Aircraft Operations Control (AOC) and Aircraft Administrative Control (AAC) functions for many years. The networks, systems and applications providing this functionality are well established, and aircraft equipage is widespread. Since the mid 1990s the systems and networks designed for this function have been expanded to provide limited Air Traffic Control (ATC) applications.
Datalink technology is intended to provide enhancements to the processes used within the provision of Air Traffic Services. In its most simplistic form, the radio communications between Air Traffic Control (ATC) and aircraft could be accomplished by digital data transmission using datalink. However the provision of datalink facilities may give rise to significant benefits in the following areas1.
Capacity
Range
Reliability
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CAP 670 Air Traffic Services Safety Requirements 2(18)
