Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 3484

x) © ¹ ³ whe 2t x e d f  S ³ Q( t Note The standard allowance for airborne multipath defined in may be used to bound the multipath errors 3.5.8.4.4 Recommendation For departure en route terminal and non precision approach operations the receiver Note uidance material on the interface providers is given in Attachment D 3 6 round based augmentation system AS and ground based regional augmentation s RAS Note In this section except where specifically annotated reference roach with vertical guidance (AP ) means AP I and AP II 3. GENERAL The GBAS shall consist of a ground subsyste and an aft subsystem. The GBAS ground subsystem shall provide data and corrections for the GNSS ranging signals over a digital VHF data broadcast to the aircraft subsystem. The GRAS ground subsystem shall consist of one or more GBAS ground subsystems. Note uidance material is provided in Attachment D should use the broadcast ionospheric corrections when available and a tropospheric model with performance e ual to that specified in 3.5.9 INTERFACE BETWEEN SBAS between different S AS service ystem to app 6.1 m aircr A 23/11/06 2007/70/II. szám Annex 10 — Aeronautical Communications Volume I 3.6.2 RF CHARACTERISTICS 3.6.2.1 Carrier fre uency stability. The carrier frequency of the data broadcast shall be maintained within 0.0002 per BAS messages shall be assembled into symbols, each consisting of 3 onsecutive message bits. The end of the message shall be padded by 1 or 2 fill bits if necessary to form the last 3-bit symbol f th Note The carrier phase for the th symbol (I ) is given by I I ǻI 3.6.2.3 Modulation wave form and pulse shapi . The output f differential phase encoder shall be filtered by a ulse shaping filter whose output, s(t), is describe s(t) e h (t kT) f I  ¦ k se of a raised-cosine filter with Į 0.6. The time cent of the assigned frequency 3.6.2.2 it to phase change encoding. G c o e message. Symbols shall be converted to D8PSK carrier phase shifts (ǻIk) in accordance with Table B-58. ng filters o d as follows: p k k j k f where h the impulse response of the raised cosine filter; I (as defined in 3.6.2.2); t time; and T the duration of each symbol 1/10 500 second. his pulse shaping filter shall have a nominal complex frequency respon T response, h(t), and frequency response, H(f), of the base band filters shall be as follows: t t sin cos T T h(t) t 2 t T T S SD § · § · ¨ ¸ ¨ ¸ © ¹ © ¹ ª º S D § ·  « » ¨ ¸ © ¹ « » ¬ ¼ for f 2T 1 sin (2fT 1) H(f ) for f 2T 2T for f 2T  D ­ d ° ° S § · °   ¨ ¸ °  D  D ° D © ¹ d d ® °  D ° ! ° 3.6.2.4 Error vector magnitude The error vector magnitude of the transmitted signal shall be less than 6.5 per cent ot 3.6.2.5 RF data rate. The symbol rate shall be 10 500 symbols per second 0.005 per cent, resulting in a nominal bit te ° °¯ The output s(t) of the pulse shaping filter shall modulate the carrier. ro -mean-square (1 sigma). ra of 31 500 bits per second. 23/11/06 A 2007/70/II. szám A endix Annex 10 — Aeronautical Communications able Data encoding Message bits Symbol phase shift I I I ǻI 1ʌ/4 2ʌ/4 4ʌ/4 5ʌ/4 6ʌ/4 7ʌ/4 Note Ij is the where I is the firs 3k-2 3k-1 3k k 0ʌ/4 3ʌ/4 jth bit of the burst to be transmitted t bit of the training se uence ed time slots. Under all operating conditions, the maximum pow z channel ba , when measured assigned time slot, shall eed 105 dBc referenced to the authorized transmitter power. Note If the authori ed transmitter power is higher than the d c may not protect reception of emissions in a s 3.6.3 DATA STRUCTURE 3.6.3. 3. ast timing structure. The time division multiple access (TDMA) timing structure shall be based on frames and time slots. Each frame shall b re shall be 2 such frames contained in each 1-second UTC epoch. The first of these frames shall start at the beginning of the UTC epoch and the second frame shall start 0.5 seconds after the beginning of the UTC epoch. The frame shall be on multipl t it shall consist of 8 individual time slots (A to H) of 62.5-millisecond duration. 3.6.3.1.2 u ime slot shall contain at most 1 burst. To initiate the use of time slot, the GBAS shall broadcast a burst i frames. ime slot in use, the ground subsystem shall broadcast a burst i of every 5 consecutive frames. Note ursts messages and may be of var th up to the max m allowed within the slot as re uired by Note During n the airborne receiver may not receive the first bursts 3.6.3.1.3 Timing b 3.6.3.1.3.1 Each burst shall be contained in a 62.5-millisecond time slot. 3.6.2.6 Emissions in unassign er over a 25 kH ndwidth, centred on the assigned frequency over any un not exc lot assigned to another desired transmitter for receivers within metres from the undesired transmitting antenna 1 TRANSMITTER TIMIN 6.3.1.1 Data broadc e 500 milliseconds in duration. The time divisi exed such tha rsts. Each assigned t a n that time slot in each of 5 consecutive For each t n at least 1 frame contain one or more iable leng imu time slot initiatio udget for bursts A 23/11/06 2007/70/II. szám Annex 10 — Aeronautical Communications Volume I 3.6.3.1.3.2 The beginning of the burst shall occur 95.2 microseconds after the beginning of the time slot with a ols). Note The transmitter power stabili ation period may be used by the aircraft receiver to settle its automatic gain 3.6.3.1.5 Ramp down. After the final information symbol is transmitted in an assigned time slot, the transmitter output power level shall decrease to at least 30 dB below the steady-state power within 285.7 microseconds (3 symbols). 3.6.3.2 urst organi ation and coding. Each burst shall consist of the data elements shown in Table B-60. Encoding of e messages shall follow the sequence: application data formatting, training sequence forward error correction (FEC) generation, application FEC gene ation lin 3.6.3.2.1 Synchroni ation and a bi sol on d am ty resolution field shall consist of the 48-bit sequence shown below, with the h ost bit tran t: 010 001 111 1 0 001 1 0 00 11 010 000 Event Nominal percentage of steady-state power tolerance of 95.2 microseconds. 3.6.3.1.3.3 For GBAS/E equipment, the start of the synchronization and ambiguity resolution portion of the burst, transmitted with horizontal polarization (HPOL), shall occur within 10 microseconds of the start of the burst transmitted with vertical polarization (VPOL). Note Table illustrates the burst timing 3.6.3.1.4 Ramp up and transmitter power stabili ation. The transmitter shall ramp up to 90 per cent of the steady-state power level within 190.5 microseconds after the beginning of the burst (2 symbols). The transmitter shall stabilize at the steady-state power within 476.2 microseconds after the beginning of the burst (5 symb control th r and bit scramb g. m guity re ution. The synchr ization an bigui rig tm smitted firs 101 111 1 100 011 101 0 0 011 able urst timing Nominal event duration Ramp-up 190.5 s to 90 Tran to 100 S s Transmission of scrambled data 58 761.9 s Ramp-down 285.7 s (Note 1) to 0 Notes Event duration indicated for transmission of scrambled data is for maximum application data length of bits fill bits and nominal symbo smitter power stabilization 285.7 s ynchronization and ambiguity resolution 1 523.8 l duration These timing re uirements provide a propagation guard time of microseconds allowing for a one way propagation range of approximately m ( NM) here bursts from a AS broadcast antenna can be received at a range more than m ( NM) greater than the range from another broadcast antenna using the next adjacent slot a longer guard time is re uired to avoid loss of both bursts To provide a longer guard time it is necessary to limit the application data length of the first burst to bits This allows a difference in propagation ranges of up to m ( NM) without conflict 23/11/06 A 2007/70/II. szám A endix Annex 10 — Aeronautical Communications able urst data content Element Data content Number of bits Beginning of burst all zeros Power stabilization Synchronization and ambiguity resolution 3.6.3.2.1 Scrambled data: 3.6.3.3 station slot identifier (SSID) 3.6.3.3.1 transmission length 3.6.3.3.2 training sequence FEC 3.6.3.3.3 application data 3.6.3.3.4 up to 1 776 application FEC 3.6.3.3.5 fill bits (Note) 3.6.2.2 0 to 2 Note Data scrambling of the fill bits is optional ( ) 3.6.3.3 SCRAM ED DATA C NTENT 3.6.3.3.1 Station slot identifier (SSID) The SSID shall be a numeric value corresponding to the letter designation A to H of the first time slot assigned to the GBAS ground subsystem, where slot A is represented by 0, B by 1, C by 2, and H by 7. The identifier is transmitted LSB first. the total number of bits in both application data and where Pn the nth bit of the training (P1 shall be transm first); SSIDn the nth bit of the station sl ); TLn the nth bit in the transmis ; and HT the transpose of the parity efined below: 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 T 3.6.3.3.2 Transmission length. The transmission length shall indicate application FEC. The transmission length is transmitted LSB first. 3.6.3.3.3 Training se uence FEC. The training sequence FEC shall be computed over the SSID and transmission length fields, using a (25, 20) block code, in accordance with the following equation: P1, ..., P5 SSID1, , SSID3, TL1, , TL17 HT sequence FEC itted ot identifier (SSID1 LSB sion length (TL1 LSB) matrix, d 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 1 1 HT 1 1 0 0 0 1 1 1 0 0 1 1 0 0 0 0 1 1 1 1 1 1 0 1 1 0 1 1 0 1 0 1 0 0 1 1 0 0 1 1 0 1 1 0 1 0 0 1 1 1 1 0 0 1 0 1 0 1 0 1 Note This code is capable of correc d detec of possible double bit errors 3.6.3.3.4 Application data. The appli f one or re message blocks, as defined in 3.6.3.4. The message blocks shall be mapped directly in data with no ad onal overhead of intervening layers. 3.6.3.3.5 Application FEC. The application FEC shall be calculated using the application data by means of a systematic, xed-length, Reed-Solomon (R-S) (255, 249) code. ting all single bit errors an ting cation data shall consist o mo to the application diti fi A 23/11/06 2007/70/II. szám Annex 10 — Aeronautical Communications Volume I 3.6.3.3.5.1 The field-defining primitive, p(x), of the R-S code shall be: p(x) x8 x7 x2 x 1 where Į is a root of p(x) used for construction of the Galois Field of size 28, GF(256), and Di is the ith primitive element in GF(256). d, m(x), shall be grouped into 8-bit R-S symbols. ll l be ordered such as specified in Tables B-61 and -62 he a248 represents the message block identifier, with the rightmost bit defined as the LSB and the first bit of the application h e block CRC, with the leftmost bit defined as the MSB and the last bit of the ap ; and 3.6.3.3.5.4 The 6 R-S check symbols (bi) shall be defined as the coefficients of the remainder resulting from dividing the message polynomial x6m(x) by the generator polynomial g(x): i 8-bit R-S check symbol shall bler shall be the MSB of b0 Note This R S code is capable of correcting up to symbol errors Note The order of the transmitted bit R S chec symbols of the appended application FEC differs from the F ata symbol is transmitted S first are given in Attachment D 3.6.3.3.5.2 The generator polynomial of the R-S code, g(x), shall be: i g(x) (x ) x x x x x x  D  D  D  D  D  D  D  i 120 3.6.3.3.5.3 In generating the application FEC, the data to be encode A data fields in the message blocks that define the application data shal B , and in the message tables in 3.6.6. However, since the R-S code is a block code, application data blocks shorter than 249 bytes (1 992 bits) shall be extended to 249 bytes by virtual fill bits set to zero and appended to the application data. These virtual fill bits shall not be transferred to the bit scrambler. The data to be encoded, m(x), shall be defined by: w re length represents the number of 8-bit bytes in the application data block; data sent to the bit scrambler; a248-length 1 represents t e last byte of the messag plication data sent to the bit scrambler a248-length, ..., a1, a0 are the virtual fill bits (if any). b(x) i 0 ¦ b ix b5x b4x b3x b2x b1x b0 x m(x) mod g(x) 3.6.3.3.5.5 The 8-bit R-S check symbols shall be appended to the application data. Each e transmitted MSB first from b to b , i.e. the first application FEC bit transferred to the bit scram b and the last application FEC bit transferred to the bit scrambler shall be the LSB of b5. d lin ( D ) Mode Moreover for D Mode each R S chec Note Example results of application FEC encoding 23/11/06 A 2007/70/II. szám A endix Annex 10 — Aeronautical Communications able Format of a AS message block Message block Bits Message block header Message up to 1 696 CRC able 62 Format of message block eader Data field Bits Messag GBAS I e block identifier D Message type identifier Message length 3.6.3.3.6 it scrambling 3.6.3.3.6.1 The output of a pseudo-noise scrambler with a 15-stage generator register shall be exclusive OR ed with the burst data starting with the SSID and ending with the application FEC. Bit scrambling of the fill bits is optional and the set value of the fill bits is optional. 3.6.3.3.6.2 The polynomial for the register taps of the scrambler shall be 1 x x15. The register content shall be rotated 1011 00 bit in the first stage of the register. The first output bit of the scrambler shall be sampled prior to e f r f the data shall be as shown in the message bles in 3.6.6. All data fields in the message block shall be transmitted in the order specified in the message tables, with the .4 identifier ( a message length, as shown in Table B-62. oding: 1010 1010 normal GBAS message Note The fill bits are not used by the aircraft receiver and their values have no impact on the system at the rate of one shift per bit. The initial status of the register, prior to the first SSID bit of each burst, shall be “1101 0010 1”, with the leftmost th irst egister shift. Note A diagram of the bit scrambler is given in Attachment D 3.6.3.4 Message bloc format. The message blocks shall consist of a message block header, a message and a 32-bit CRC. Table B-61 shows the construction of the message block. All signed parameters shall be two s complement numbers and all unsigned parameters shall be unsigned fixed point numbers. The scaling o ta LSB of each field transmitted first. Note All binary representations reading left to right are MS to S 3.6.3 .1 Message bloc header. The message block header shall consist of a message block identifier, a GBAS ID), a message type identifier and Message bloc identifier the 8-bit identifier for the operating mode of the GBAS message block. C 1111 1111 test GBAS message All other values are reserved. A 23/11/06 2007/70/II. szám Annex 10 — Aeronautical Communications Volume I AS ID the four-character GBAS identification to differentiate between GBAS ground subsystems. Coding: Each nal Alphabet No. 5 (IA-5) representation. For each character, bit b1 is transmitted first and six bits are transmitted for each character. Only upper case letters, numeric nearest airport Assignment of AS IDs will e coordinated as appropriate to avoid conflicts essage type identifier the numeric label identifying the content of the message (Table B-63). essage length the length of the message in 8-bit bytes including the 6-byte message block header, the message and the 4-byte message CRC code. 3.6.3.4.2 Cyclic redundancy The GBAS message CRC shall be calculated in accordance with 3.9. 3.6.3.4.2.1 The length of the CRC code shall be k 32 bits. 3.6.3.4.2.2 The CRC generator po omial G(x) x x31 3.6.3.4.2.3 The CRC information ld, M(x M m xn i m xn 1 m xn 2 mnx0 3.6.3.4.2.4 M(x) shall be form th der and all bits of the variable-length message, excluding the CRC. Bits ng e order transmitted, such that m1 corresponds to the first transmitted bit of the message block header, and m corresponds to the last transmitted bit of the (n-48) message bits. .2.5 red such that r1 is the first bit transmitted and r32 is the last bit transmitted. 3.6.4 DATA CONTENT 3.6.4.1 Message types. The message types that can be transmitted by GBAS shall be as in Table B-63. ddresse the differential correction data for individual GNSS ranging sources

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