Manual foraeronautical mobile satellite (route) service




старонка1/37
Дата канвертавання15.04.2016
Памер6.13 Mb.
  1   2   3   4   5   6   7   8   9   ...   37


MANUAL FORAERONAUTICAL

MOBILE SATELLITE (ROUTE) SERVICE

Part III – Inmarsat and MTSAT

Preliminary Unedited DRAFT Version – 20 February 2007




Disclaimer
Please note, this part of the AMS(R)S manual has been posted to the ACP website as a draft. The contents shown, including paragraph numbers, are subject to change, pending editorial revision and further technical input.
AMS(R)S Standards and Recommended Practices (SARPs) as contained in Annex 10, Volume III, Part I, Chapter 4 take in any case precedence over material contained in this document.
ICAO accepts no responsibility or liability, in whole or in part, as to the currency, accuracy or quality of the information in the manual, nor any consequence of its use.
Part III of the manual deals with aeronautical mobile satellite communications, using the “classic” Inmarsat and the MTSAT Satellite Networks.

MANUAL ON AERONAUTICAL

MOBILE-SATELLITE SERVICE

4.1    DEFINITIONS AND DESCRIPTIONS

OF CHANNEL TYPES; GENERAL;

SYSTEM CAPABILITIES

4.1.1    Definitions and descriptions

of channel types
4.1.1.1    Definitions
Application. The ultimate use of an information system, as distinguished from the system itself.
Aviation-BPSK (A-BPSK). The particular form of binary phase shift keyed modulation which is used in AMSS for channel rates of 2.4, 1.2 and 0.6 kbits/s. A-BPSK is a modulation technique which maps a “0” to a phase shift of –90 and “1” to a phase shift of +90. The phase-encoded A-BPSK data stream is then filtered with a filter which satisfies the amplitude and phase versus frequency limits defined by Tables A1-1 and A1-2 in Appendix 1 to Chapter 4.
Aviation-QPSK (A-QPSK). The particular form of offset quaternary phase shift keyed modulation which is used in AMSS for channel rates greater than 2 400 bits/s. A-QPSK is a modulation technique which maps a “0” into a 0 degrees and “1” into a 180 degrees, or “0” into 90 degrees and “1” into 270 degrees, alternating between the two options on successive bits. The encoded A-QPSK data stream is then filtered such that the modulated spectrum meets the amplitude mask of Table A1-3 and the phase mask defined in Table A1-2 in Appendix 1 to Chapter 4.
Burst. A time-defined, contiguous set of one or more related signal units which may convey user information and protocols, signalling, and any necessary preamble.
Cyclic redundancy check. The last two bytes of each signal unit form a cyclic redundancy check of the whole signal unit as follows. The check bits for error detection are calculated from the first 10 octets of a standard length signal unit, or from the first 17 octets of an extended length signal unit or from the first 4 octets of the burst identifier, using the following generator polynomial:
x16 + x12 + x5 + 1
Note.— See CCITT (Red Book) Recommendation X.25, Section 2.2.7 for the method of calculation and the bit order.
Direct link service (DLS). A data communications service which makes no attempt to automatically correct errors, detected or undetected, at the link layer of the air-ground communications path. (Error control may be effected by end-user systems.)
Epoch. A span of time related to the beginning and end, or lifetime, of an event or a sequence of associated events.
Frame. A structured, repeating time-segment of a communication link architecture that provides for time-predictable communication activities between its beginning and end.
Global beam. Satellite antenna directivity whose main lobe encompasses the entire earth’s surface that is within line-of-sight view of the satellite.
Initial signal unit (ISU). The first of the series of signal units followed by SSUs.
Link interface control information (LICI). The control information exchanged between the link layer and any of its service users as part of the link interface data unit (LIDU).
Link interface data unit (LIDU). The total information transferred in a single interaction across the interface between the link layer and a link service user. Each LIDU contains link interface control information (LICI) and may also contain a single link service data unit (LSDU).
Link service data unit (LSDU). A part of the link interface data unit (LIDU) and is the same as the subnetwork protocol data unit (SNPDU).
Lone signal unit (LSU). A single signal unit comprising the total message.
Near-geostationary orbits. Satellites operating in near-geostationary orbits have an orbit period of 24 hours with an inclination of up to five degrees from the equatorial plane.
Network co-ordination station (NCS). The entity of the over-all AMS(R)S system that has functional responsibilities to: co-ordinate communications traffic and satellite connectivity within its satellite region; and provide inter-system co-ordination with adjacent satellite regions served by other satellites.
P channel synchronization. The state of the P channel demodulator when the P channel unique word is reliably detected.
P channel degradation/loss. A declaration that is made when the P channel bit error rate rises above 10–4 over an averaging period of 3 minutes, or more than 10 short-term interruptions (loss of P channel synchronization for less than 10 seconds) are experienced in any 3-minute period; or when the P channel synchronization is lost for more than 10 seconds.
Q number, Q level, Q precedence. A definition of the transmission precedence of a message or signalling sequence, using numbers from 0 to 15 (with 15 transmitted first).
Reliable link service (RLS). A data communications service provided by the subnetwork which automatically provides for error control over its link through error detection and requested retransmission of signal units found to be in error.
Satellite region. A geographically defined sub-area within the view of a satellite within which services can be provided by that satellite.
Satellite service area. A geographically defined sub-area within the view of a satellite within which services are provided by that satellite. Note that a satellite service area might be sub-divided in terms of operational characteristics, conditions, or limitations for a variety of reasons.
Signal unit (SU). A time-ordered, contiguous set of data octets used for signalling and control, and for user packet data transmissions. Standard-length SUs are 96 bits (12 octets) used in P, T and C channels. R channel SUs are 152 bits (19 octets), and the T channel uses a header SU of 48 bits (6 octets).
Spot beam. Satellite antenna directivity whose main lobe encompasses significantly less than the earth’s surface that is within line-of-sight view of the satellite. May be designed so as to improve system resource efficiency with respect to geographical distribution of user earth stations.
Subsequent signal unit (SSU). In a series of SUs, the signal unit(s) following the initial signal unit.
Superframe. A recurring, time-structured set of data trans-mission frames, which also includes a superframe marker (see also the definition of “frame”).

4.1.1.2    Description of



channel types
4.1.1.2.1    P channel. Packet mode time division multiplex(TDM) channel transmitted continuously from the aeronautical ground earth station (GES) in the to-aircraft direction to carry signalling and user data. A P channel being used for system management functions is designated Psmc, while a P channel being used for other functions is designated by Pd. The functional designations Psmc and Pd do not necessarily apply to separate physical channels.
4.1.1.2.2    R channel. Random access (slotted Aloha) channel, used in the from-aircraft direction to carry signalling and user data. An R channel being used for system manage-ment functions is designated Rsmc, while an R channel being used for other functions is designated Rd. The functional designations Rsmc and Rd do not necessarily apply to separate physical channels.
4.1.1.2.3    T channel. Reservation time division multiple access (TDMA) channel, used in the from-aircraft direction only. The receiving GES reserves time slots for transmissions requested by aircraft earth stations (AESs) according to message length. The sending AES transmits the message in the reserved time slots according to priority.
4.1.1.2.4    C channel. Circuit-mode single channel per carrier (SCPC) channel, used in both to-aircraft and from-aircraft directions. This channel is time division multiplexed to provide a primary channel for voice or data traffic and a sub-band channel for signalling, supervision and data messages. The use of the channel is controlled by assignment and release signalling at the start and end of each transaction.

4.1.2    General
4.1.2.1    When aeronautical mobile-satellite service (AMSS), using near-geostationary orbiting satellites, is installed and maintained in operation as an aid to air traffic services, it shall conform with the provisions of 4.1 to 4.10.
4.1.2.2    Requirements for mandatory carriage of AMSS equipment including the level of system capability shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation time-scales for the carriage of equipment.
4.1.2.3    The agreements indicated in 4.1.2.2 shall provide at least two years’ notice of mandatory carriage of airborne systems.
4.1.2.4    Recommendation.— Civil aviation authorities should co-ordinate, with national authorities and service providers, those implementation aspects of AMSS which will permit its world-wide interoperability and optimum use, as appropriate.
Note.— Provisions on the allocation and assignment of 24-bit aircraft addresses for use by the AMSS are contained in Chapter 9.

4.1.3    System capabilities
Note.— A system providing aeronautical mobile-satellite service (AMSS) comprises the AES, the satellite and the GES. A Level 1 (2, 3 or 4) system consists of an AES with Level 1 (2, 3 or 4) capability with one or more satellites and one or more GESs having the capabilities to operate compatibly with all capabilities of the AES. Multiple service providers of such systems may coexist. A basic level of interoperability among different systems is provided.
4.1.3.1    Scope. A level of system capability shall include the performance of the AES, the satellite and the GES. All AESs, as a minimum, shall have a Level 1 capability and shall continuously monitor the P channel after log-on to the GES. Each GES shall provide at all times when operating AMS(R)S, a Level 1 capability as a minimum.
4.1.3.1.1    There shall be a P channel and an R channel Psmc and Rsmc capability which perform system management functions for each satellite service area.
4.1.3.1.2    For the case where there is one transmit channel unit shared between the R and T channels, R channel transmissions shall be delayed, whenever necessary, to avoid interrupting a T channel transmission.
4.1.3.2    Level 1. An AES with Level 1 capability shall have the capabilities for:
a) receiving and processing data on one P channel at channel rates of 0.6 and 1.2 kbits/s; and
b) processing and transmitting data on one R channel and on one T channel at channel rates of 0.6 and 1.2 kbits/s.
Simultaneous transmission on the R channel and the T channel shall not be required.

4.1.3.2.1    An AES with Level 1 capability shall receive and process continuously the assigned P channel once logged on with the GES to enable receipt of AES-addressed messages and respond to GES commands.


4.1.3.2.2    Recommendation.— An AES with Level 1 capability should have the capabilities described in 4.1.3.2 for the additional channel rate of 2.4 kbits/s.
Note.— An AES with Level 1 capability provides basic packet mode data communications based on the open system interconnection model to support aviation safety communications. An AES with Level 1 capability requires one receive channel and one transmit channel.
4.1.3.3    Level 2. An AES with Level 2 capability shall have the capabilities for:
a) receiving and processing data on one P channel at channel rates of 0.6 and 10.5 kbits/s; and
b) processing and transmitting data on one R channel and on one T channel at channel rates of 0.6 and 10.5 kbits/s.
Simultaneous transmission on the R channel and the T channel shall not be required. Simultaneous reception on more than one P channel shall not be required.
4.1.3.3.1    Recommendation.— An AES with Level 2 capability should have the capabilities described in 4.1.3.3 a) for the additional channel rate of 4.8 kbits/s.
4.1.3.4    Level 3. An AES with Level 3 capability shall provide the capabilities for:
a) an AES with Level 2 capability; and
b) receiving, processing and transmitting digital information on one C channel at a channel rate of 8.4 or 21.0 kbits/s.
Simultaneous operation of the C channel with either the R channel or the T channel shall not be required.
4.1.3.4.1    Recommendation.— Level 3 channel capability should be provided at channel rates of 5.25, 6.0 and 10.5 kbits/s.
Note.— An AES with Level 3 capability provides digitized voice capability on a C channel in addition to the Level 2 packet mode data capability. Pre-emption requirements are described in Sections 4.8 and 4.9. Two receive channels and one transmit channel are required.
4.1.3.5    Level 4. An AES with Level 4 capability shall provide the capabilities for:
a) an AES with Level 3 capability;
b) simultaneous operation of a C channel with the R channel; and
c) simultaneous operation of the C channel with the T channel.
Simultaneous operation of the three channels (C, R and T) shall not be required.
4.1.3.5.1    Recommendation.— Level 4 channel capability should be provided at channel rates of 5.25, 6.0 and 10.5 kbits/s.
Note.— An AES with Level 4 capability provides digitized voice capability on a C channel simultaneously with packet mode data capability on the R channel or the T channel. Two receive channels and two transmit channels are required.
4.1.3.5.2    Recommendation.— A Level 4 AES should be capable of simultaneous R and T channel transmissions whenever the C channel is not in use.

4.2    BROADBAND RF

CHARACTERISTICS

4.2.1    Frequency bands
4.2.1.1    Use of AMS(R)S bands
Note.— Categories of messages, and their relative priorities within the aeronautical mobile (R) service, are given in Annex 10, Volume II, 5.1.8. These categories and priorities are equally valid for the aeronautical mobile satellite (R) service (see ITU Radio Regulations Article S44).
4.2.1.1.1    Every aircraft earth station and ground earth station shall be designed to ensure that messages defined in Annex 10, Volume II, 5.1.8 are not delayed by the transmission and/or reception of other types of messages employing frequencies within the bands stated in 4.2.1.2 and 4.2.1.3 or other frequencies to which the station can tune. Message types not defined in Annex 10, Volume II, 5.1.8 shall be terminated if necessary, and without warning, to allow Annex 10, Volume II, 5.1.8 type messages to be transmitted and received.
Note.— See ITU Radio Regulations No. S5.357A.

4.2.1.2    To-aircraft


4.2.1.2.1    The aircraft earth station shall be capable of receiving in the frequency band 1 544 to 1 555 MHz.
Note.— Use of the band 1 544 to 1 545 MHz by mobile satellite services is limited to distress and safety operations.
4.2.1.2.2    Recommendation.— The aircraft earth station should be capable of receiving in the frequency band 1 555 to 1 559 MHz.
Note.— The band 1 555 to 1 559 MHz may be protected and utilized by some States for national and international AMS(R)S purposes.
4.2.1.2.3    Recommendation.— The aircraft earth station should also be capable of receiving in the frequency band 1 525 to 1 544 MHz.
Note.— The band 1 525 to 1 544 MHz may be used to communicate for purposes of distress and public correspondence with stations of the maritime mobile satellite service in accordance with ITU Radio Regulations Article S41.

4.2.1.3    From-aircraft


4.2.1.3.1    The aircraft earth station shall be capable of transmitting in the frequency band 1 645.5 to 1 656.5 MHz.
Note.— Use of the band 1 645.5 to 1 646.5 MHz by mobile-satellite services is limited to distress and safety operations.
4.2.1.3.2    Recommendation.— The aircraft earth station should be capable of transmitting in the frequency band 1 656.5 to 1 660.5 MHz.
Note.— The band 1 656.5 to 1 660.5 MHz may be protected and utilized by some States for national and international AMS(R)S purposes.
4.2.1.3.3    Recommendation.— The aircraft earth station should also be capable of transmitting in the frequency band 1 626.5 to 1 645.5 MHz.
Note.— The band 1 626.5 to 1 645.5 MHz may be used to communicate for purposes of distress and public correspondence with stations of the maritime mobile satellite service in accordance with ITU Radio Regulations Article S41.
4.2.1.4    Tuning increments
4.2.1.4.1    Channels shall be allocated throughout the bands in increments of 2.5 kHz, for the to- and from-aircraft transmission path.
4.2.1.4.2    Channel assignment and tuning of the aircraft earth station shall be achieved under control from the GES.

4.2.1.5    Channel numbering


4.2.1.5.1    The channel number (Ct) shall be defined with respect to the centre frequency on the to-aircraft transmission path by the formula:


Ct =

frequency of transmission (MHz) 1510.0

0.0025

4.2.1.5.2    The channel number (Cf) shall be defined with respect to the centre frequency on the from-aircraft transmission path by the formula:




Cf =

frequency of transmission (MHz) 1611.5

0.0025


4.2.2    Frequency accuracy
The frequency of transmission from the aircraft earth station, as would be received at the satellite, shall not vary from the nominal channel frequency by more than ±383 Hz due to all causes.
Note.— The frequency of transmissions received by a subsonic aircraft should not vary from the nominal channel frequency by more than ±2.18 kHz due to all causes.


4.2.3    Aircraft earth stations

RF characteristics
Note.— The following requirements apply over the entire transmit and receive frequency bands.

4.2.3.1    General antenna

characteristics
4.2.3.1.1    Reference coverage volume. Antenna systems shall be installed to meet performance requirements for transmitting and receiving over a coverage volume of 360 degrees of azimuth and from 5 to 90 degrees in elevation from a horizontal plane for aircraft in straight and level flight.
4.2.3.1.1.1    Recommendation.— To the maximum extent possible, antenna systems should be installed to meet perform-ance requirements for transmitting and receiving over a coverage volume of 360 degrees in azimuth and from 5 to 90 degrees in elevation from a horizontal plane for aircraft attitudes of +20/–5 degrees of pitch and ±25 degrees of roll.
4.2.3.1.2    Polarization. The polarization shall be right hand circular for both receiving and transmitting, in accordance with the definition of ITU Radio Regulations No. S1.154.
4.2.3.1.3    Antenna switching. Aircraft earth stations that require more than one antenna shall be capable of switching from one antenna to another in the same antenna sub-system so as to introduce a signal interruption of not more than 40 ms.
Note.— 4.2.3.2, 4.2.3.2 bis and 4.2.3.3 outline the require-ments for high gain, intermediate gain and low gain antennas only. This does not preclude the future introduction of other gain antennas; however, some of the considerations which must be made before such an introduction are described in the guidance material contained in Attachment A to Part I of Annex 10, Volume III.

4.2.3.2    Low gain antenna

sub-systems
4.2.3.2.1    Gain-to-noise temperature ratio. Receiving sub-systems employing low gain antennas shall achieve a gain-to-noise temperature ratio (G/T) of not less than –26 dB/K over not less than 85 per cent of the reference coverage volume defined in 4.2.3.1.1; and not less than –31 dB/K over the remaining 15 per cent of the reference coverage volume. The only exception to this is the region greater than 70 degrees in elevation from the horizontal plane where the G/T shall be not less than –28 dB/K.
4.2.3.2.2    Axial ratio. The axial ratio shall be less than 6 dB for elevation angles of 45 to 90 degrees and less than 20 dB for elevation angles of 5 to 45 degrees or the AES antenna shall have sufficient gain to compensate for additional polarization loss in excess of that caused by the axial ratios. The condition for including the compensation shall assume the satellite axial ratio to be 2.5 dB, with major axes of the polarization ellipses orthogonal.
4.2.3.2.3    Recommendation.— To the maximum extent possible, the G/T should be not less than –26 dB/K and the axial ratio should be less than 6 dB over 100 per cent of the reference coverage volume.

4.2.3.2 bis    Intermediate gain antenna

sub systems
See paragraph 4.2.3.6.

4.2.3.3    High gain antenna

sub-systems
4.2.3.3.1    Gain-to-noise temperature ratio. Receiving sub-systems employing high gain antennas shall achieve a gain-to-noise temperature ratio (G/T) of not less than –13 dB/K over not less than 75 per cent of the reference coverage volume and shall be not less than –25 dB/K over the remaining 25 per cent of the reference coverage volume defined in 4.2.3.1.1.
4.2.3.3.2    Axial ratio. The axial ratio shall be less than 6 dB over the 75 per cent of the reference coverage volume referred to in 4.2.3.3.1 where the G/T must exceed –13 dB/K or the AES antenna shall have sufficient gain to compensate for additional polarization loss in excess of that caused by this axial ratio. The condition for including the compensation shall assume the satellite axial ratio to be 2.5 dB, with the major axes of the polarization ellipses orthogonal.
4.2.3.3.3    Recommendation.— To the maximum extent possible, the G/T should be not less than –13 dB/K and the axial ratio should be less than 6 dB over 100 per cent of the reference coverage volume.
4.2.3.3.4    Discrimination. The antenna gain pattern for both transmit and receive functions shall discriminate by not less than 13 dB between the directions of wanted and unwanted satellites spaced 45 degrees or greater in longitude over not less than 75 per cent of the reference coverage volume defined in 4.2.3.1.1.
4.2.3.3.4.1    Recommendation.— The antenna gain pattern for both transmit and receive functions should discriminate by not less than 13 dB between the directions of wanted and unwanted satellites spaced 45 degrees or greater in longitude over 100 per cent of the reference coverage volume defined in 4.2.3.1.1.
4.2.3.3.5    Phase discontinuity. Beam steering transitions between adjacent beam positions of a switched beam antenna shall not cause RF phase transitions greater than 12 degrees in the transmitted signal for 99 per cent of all possible adjacent beam combinations.
4.2.3.3.5.1    Recommendation.— Beam steering tran-sitions between adjacent beam positions of a switched beam antenna should not cause RF phase transitions greater than 12 degrees in the transmitted signal for 100 per cent of all possible adjacent beam combinations.
Note.— This requirement only applies to individual array performance in the case of multiple array antennas.

4.2.3.4    Receiver

requirements
4.2.3.4.1    Receiver spurious and linearity performance. The required performance defined in 4.4.2.3 and 4.4.5.4 shall be achieved when the receiving antenna is illuminated in the direction of maximum gain by a power flux density of –100 dBW/m2 distributed across the 1 525 to 1 559 MHz band.
4.2.3.4.2    Receiver out-of-band performance. The required performance defined in 4.4.2.3 and 4.4.5.4 shall be achieved in the presence of out-of-band interference at levels typical of normal operating conditions.
4.2.3.4.3    Received phase noise. The design of the receiver and the demodulators shall be such as to ensure full compliance with the performance requirements whenever the received signal phase noise characteristic does not exceed the mask defined in Table 4-1.*
4.2.3.4.4    Capture range. The receiver shall be capable of acquiring and maintaining lock to signals with a frequency offset from nominal of up to ±2.180 kHz at carrier-to-noise levels as shown in Table 4-2.
4.2.3.4.5    Receiver Doppler rate. The receiver shall be capable of acquiring and maintaining performance per 4.3.3 with a rate of change of frequency of 30 Hz per second.

4.2.3.5    Transmitter

requirements
4.2.3.5.1    EIRP limits
4.2.3.5.1.1    For low gain antenna operation, the minimum value of EIRP per carrier in the direction of the satellite, when commanded to the maximum setting, shall be 13.5 dBW. The EIRP radiated in any direction shall not exceed 22.8 dBW.
4.2.3.5.1.1 bis    For intermediate gain antenna operation, the minimum value of EIRP per carrier in the direction of the satellite, when commanded to the maximum setting, shall be 12.5 dBW. The EIRP radiated in any direction shall not exceed 34.8 dBW at the maximum setting.
4.2.3.5.1.2    For high gain antenna operation, the minimum value of EIRP per carrier in the direction of the satellite, when commanded to the maximum setting, shall be 25.5 dBW. The EIRP radiated in any direction shall not exceed 34.8 dBW at the maximum setting.
4.2.3.5.1.3    At settings less than the maximum setting, the EIRP per carrier radiated in any direction shall not exceed the EIRP radiated toward the wanted satellite by more than 5 dB.
4.2.3.5.1.4    For multicarrier operation, the maximum allowable operating EIRP shall be the level at which:
a) the total intermodulation product contribution from active sources is the maximum permitted in 4.2.3.5.7 (in-band intermodulation products), or
b) the gain-to-noise temperature ratio is the minimum permitted in 4.2.3.2.1 or 4.2.3.3.1, as applicable.
4.2.3.5.2    EIRP control. The EIRP per carrier in the direction of the wanted satellite shall be adjustable over a range of 15 dB in steps of 1 dB by command from the GES.
4.2.3.5.3    Recommendation.— The minimum EIRP of the power control range should be a function of the channel rate and the satellite beam characteristics to minimize the interference potential.
4.2.3.5.4    Carrier-off level. The EIRP in any direction, summed across the 1 626.5 to 1 660.5 MHz band, when all carriers are commanded off shall be –24.5 dBW or less.
4.2.3.5.5    Log-on EIRP. When logging on to a GES, the EIRP of the AES shall be at least 12.5 dBW.
4.2.3.5.6    In-band spurious EIRP. When transmitting a modulated carrier at any level up to the maximum allowable operating EIRP, the composite radiated in-band spurious and noise EIRP (excluding intermodulation products) referenced to a 4 kHz band shall not exceed –55 dBc. This requirement shall not apply to the frequency band on either side of the carrier centre frequency which is described in 4.3.2.1.

4.2.3.5.7    Intermodulation products


4.2.3.5.7.1    For multicarrier AES, the radiated inter-modulation products shall not cause harmful interference to satellite navigation receiver operation where such receiver is operated on the same aircraft when transmitting two equal carriers with a total power equal to the maximum allowable operating EIRP of the AES.
4.2.3.5.7.2    The AES transceiver shall not transmit on a newly assigned frequency that would produce a fifth-order intermodulation product at a frequency below 1 610.0 MHz.
4.2.3.5.7.3    Frequency management techniques shall be used to preclude 5th and lower order intermodulation products below 1 610 MHhz being radiated by the aes.
4.2.3.5.8    Out-of-band EIRP density levels. When transmitting a carrier at any level up to the maximum power level as described in 4.2.3.5.1, the out-of-band EIRP including spurious, harmonics and noise generated by the AES in any direction shall not exceed the levels shown in Table 4-3.
4.2.3.5.8.1    Recommendation.— The EIRP density should not exceed –140 dBc/1 MHz from 1 605 to 1 610 MHz.
4.2.3.5.9    Phase noise. The phase noise induced on a modulated carrier shall have a power spectral density not exceeding the envelope defined in Table 4-4.
4.2.3.5.10    Transmitter Doppler rate. The maximum rate of change of the frequency of the transmitted signal when compensated for aircraft acceleration in the direction of the satellite shall not exceed 15 Hz per second. The Doppler adjustment resolution shall not exceed 10 Hz and the associated frequency changes shall be made without introducing phase discontinuity into the transmitted signal.
4.2.3.5.11    AMSS transmissions shall not cause harmful interference to satellite navigation receiver operation where such receiver is operated on the same aircraft as the AES.

4.2.3.6    Intermediate gain antenna



sub-systems
4.2.3.6.1    Gain-to-noise temperature ratio. Receiving sub systems employing intermediate gain antennas shall achieve a gain-to-noise temperature ratio (G/T) of not less than –19 dB/K over not less than 85 per cent of the reference coverage volume defined in 4.2.3.1.1. The only exception tothis is the region greater than 70 degrees in elevation fromthe horizontal plane where the G/T shall be not less than –21 dB/K.
4.2.3.6.2    Axial ratio. The axial ratio shall be less than 6 dB over 85 per cent of the reference coverage volume referred to in 4.2.3.1.1 where the G/T must exceed –19 dB/K or the AES antenna shall have sufficient gain to compensate for the additional polarization loss in excess of that caused by this axial ratio. The condition for including the compensation shall assume the satellite axial ratio to be 2.5 dB, with the major axes of the polarization ellipses orthogonal.
4.2.3.6.3    Recommendation.— The G/T should be not less than –19 dB/K and the axial ratio should be less than 6 dB over 100 per cent of the reference coverage volume.
4.2.3.6.4    Discrimination. The antenna gain pattern for both transmit and receive functions shall discriminate by not less than 7 dB between the directions of wanted and unwanted satellites spaced 80 degrees or greater in longitude over not less than 85 per cent of the reference coverage volume defined in 4.2.3.1.1.
4.2.3.6.5    Recommendation.— The antenna gain pattern for both transmit and receive functions should discriminate by not less than 7 dB between the directions of wanted and unwanted satellites spaced 80 degrees or greater in longitude over 100 per cent of the reference coverage volume defined in 4.2.3.1.1.
4.2.3.6.6    Phase discontinuity. Beam steering transitions between adjacent beam positions of a switched beam antenna shall not cause RF phase transitions greater than 30 degrees in the phase of the receive and transmit signal for 99 per cent of all possible adjacent beam combinations.
4.2.3.6.7    Recommendation.— Beam steering transitions between adjacent beam positions of a switched beam antenna should not cause RF phase transitions greater than 30 degrees in the received and transmitted signal for 100 per cent of all possible adjacent beam combinations.

  1   2   3   4   5   6   7   8   9   ...   37


База данных защищена авторским правом ©shkola.of.by 2016
звярнуцца да адміністрацыі

    Галоўная старонка