Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 1934

b) Demand assigned circuits: This shall provide voice circuit access which is arbitrated by the ground station in response to an access request received from the aircraft station. This type of operation shall allow dynamic sharing of the channel resource increasing trunking efficiency. 6.8.1.2 Priority access. The voice unit operation shall support a priority override access for authorized ground users. 6.8.1.3 Message source identification. The voice unit operation shall support notification to the user of the source of a received message (i.e. whether the message originated from an air or ground station). 6.8.1.4 Coded squelch. The voice unit shall support a coded squelch operation that offers some degree of rejection of undesired co-channel voice messages based on the burst time of arrival. 6.8.2 Speech encoding, parameters and procedures 6.8.2.1 The VDL Mode 3 shall use the advanced multiband excitation (AMBE) 4.8 kbits/s encoding/decoding algorithm, version number AMBE-ATC-10, developed by Digital Voice Systems, Incorporated (DVSI) for voice communications. Note 1.— Information on technical characteristics of the 4.8 kbits/s AMBE algorithm is contained in AMBE-ATC-10 Low Level Description, obtainable from DVSI. Note 2.— The 4.8 kbits/s AMBE encoding/decoding technology described in the document is subject to DVSI patent rights and copyrights. Manufacturers must enter into a license agreement with DVSI prior to obtaining a detailed description of the algorithm before incorporation in equipment operating in the VDL Mode 3 service. By letter to ICAO dated 29 October 1999, DVSI confirmed its commitment to license the technology for the manufacture and sale of aeronautical equipment under reasonable terms and conditions, negotiated on a non-discriminatory basis. 6.8.2.2 Speech encoding definition, voice unit parameters, and procedure descriptions for VDL Mode 3 Voice Unit operation are contained in the Manual on VDL Mode 3 Technical Specifications. 6.9 VDL MODE 4 6.9.1 A Mode 4 station shall conform to the requirements defined in 6.1.2.3, 6.1.4.2, 6.2.1.1, 6.2.3.1, 6.2.4, 6.3.1, 6.3.3.1, 6.3.4, 6.3.5.1, 6.3.5.2, 6.3.5.3, 6.3.5.4.1 and 6.9. Annex 10 — Aeronautical Communications Volume III 22/11/07 I-6-20 6.9.2 VDL Mode 4 radio channels 6.9.2.1 VDL MODE 4 STATION FREQUENCY RANGE 6.9.2.1.1 Transmitter/receiver tuning range. A VDL Mode 4 transmitter/receiver shall be capable of tuning to any of the 25 kHz channels from 117.975 MHz through 137 MHz. The transmitter shall have a means for the tuning range to be restricted to a narrower range. Note.— Operational conditions or certain applications may require the equipment to be operated in a narrower frequency range. 6.9.2.1.2 Recommendation.— A VDL Mode 4 transmitter/receiver should be capable of tuning to any of the 25 kHz channels from 108 to 117.975 MHz. Note.— The band 108–117.975 MHz may be utilized in accordance with the relevant provisions of the ITU Radio Regulations. 6.9.2.1.3 Simultaneous reception. A VDL Mode 4 station shall be capable of receiving two channels simultaneously. 6.9.2.1.4 Recommendation.— A VDL Mode 4 station should be capable of receiving additional channels simultaneously as required by operational services. 6.9.2.2 GLOBAL SIGNALLING CHANNELS 6.9.2.2.1 VDL Mode 4 stations shall use two assigned frequencies as global signalling channels (GSC), to support user communications and link management functions. Note.— Additional channels may be defined in a local domain and notified to mobile users by broadcast from ground stations on the GSCs defined above. 6.9.3 System capabilities 6.9.3.1 ATN compatibility. The VDL Mode 4 system shall support ATN-compliant subnetwork services for surveillance applications. 6.9.3.2 Data transparency. The VDL Mode 4 system shall provide code-independent, byte-independent transfer of data. 6.9.3.3 Broadcast. The VDL Mode 4 system shall provide link layer broadcast services. 6.9.3.4 Point-to-point. The VDL Mode 4 system shall provide link layer point-to-point services. 6.9.3.5 Air-air communications. The VDL Mode 4 system shall provide air-air communications, without ground support, as well as air-ground communications. 6.9.3.6 Connection management. When supporting air-ground operations, the VDL Mode 4 system shall establish and maintain a reliable communications path between the aircraft and the ground system while allowing, but not requiring, manual intervention. 6.9.3.7 Ground network transition. A mobile VDL Mode 4 DLS station shall transition from one ground VDL Mode 4 DLS station to another as required. Part I Annex 10 — Aeronautical Communications I-6-21 22/11/07 6.9.3.8 Derived time capability. VDL Mode 4 shall provide the capability for deriving time from time-of-arrival measurements of received VDL Mode 4 transmissions whenever externally derived estimates of time are unavailable. 6.9.3.9 Simplex operations. Mobile and ground VDL Mode 4 stations shall access the physical medium operating in simplex mode. 6.9.4 Coordination of channel utilization 6.9.4.1 On a regional basis, transmissions shall be scheduled relative to UTC, to ensure efficient use of shared channels and to avoid unintentional slot re-use. 6.9.5 Physical layer protocols and services Note.— Unless otherwise stated, the requirements defined in this section apply to both mobile and ground stations. 6.9.5.1 FUNCTIONS 6.9.5.1.1 TRANSMITTED POWER 6.9.5.1.1.1 Airborne installation. The effective radiated power shall be such as to provide a field strength of at least 35 microvolts per metre (minus 114.5 dBW/m2) on the basis of free space propagation, at ranges and altitudes appropriate to the conditions pertaining to the areas over which the aircraft is operated. 6.9.5.1.1.2 Ground installation. Recommendation.— The effective radiated power should be such as to provide a field strength of at least 75 microvolts per metre (minus 109 dBW/m2) within the defined operational coverage of the facility, on the basis of free-space propagation. 6.9.5.1.2 TRANSMITTER AND RECEIVER FREQUENCY CONTROL 6.9.5.1.2.1 The VDL Mode 4 physical layer shall set the transmitter or receiver frequency as commanded by the link management entity (LME). Channel selection time shall be less than 13 ms after the receipt of a command from a VSS user. 6.9.5.1.3 DATA RECEPTION BY RECEIVER 6.9.5.1.3.1 The receiver shall decode input signals and forward them to the higher layers for processing. 6.9.5.1.4 DATA TRANSMISSION BY TRANSMITTER 6.9.5.1.4.1 Data encoding and transmission. The physical layer shall encode the data received from the data link layer and transmit it over the RF channel. RF transmission shall take place only when permitted by the MAC. 6.9.5.1.4.2 Order of transmission. The transmission shall consist of the following stages in the following order:

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