Galileo OS SIS ICD.indd - GSA - Europa

Parameter Defi nition Bits Scale
factor
Unit
E5bDVS E5b Data Validity Status 1 N/A dimensionless
E1-B DVS E1-B Data Validity Status 1 N/A dimensionless
Table 74. Data Validity Satellite Status (transmitted on E5b and E1-B)
The data validity status bit has the values shown in Table 75:
Data Validity Status Defi nition
0 Navigation data valid (tbc)
1 Working without guarantee
Table 75. Data validity Status Bit Values
The E5a signal health status transmitted on E5a-I is coded on 2 bits according to
Table 76.
Parameter Defi nition Bits Scale
factor
Unit
E5aHS E5a Signal Health Status 2 N/A dimensionless
Table 76. Signal Health Status for E5a (transmitted on E5a)
The E5b and E1-B signal health status transmitted on E5b and E1-B are coded on 2
bits according to the following table.
Parameter Defi nition Bits Scale
factor
Unit
E5bHS E5b Signal Health Status 2 N/A dimensionless
E1-B HS E1-B Signal Health Status 2 N/A dimensionless
Table 77. Signal Health Status for E5b and E1 (transmitted on E5b and E1-B)
The signal status bits have the values shown in Table 78.
5.1.9.4. Checksum
Signal Health Status Defi nition (tbc)
0 Signal OK
1 Signal out of service
2 Signal will be out of service
3 Signal Component currently in Test
Table 78. Signal Health Status Bit Values (defi nitions are tbc)
The checksum, which employs a CRC technique, is used to detect the reception of
corrupted data. The checksum does not include the frame synchronisation pattern or
the tail bit fi elds since these do not form part of the required message information. For
the F/NAV and I/NAV data, a CRC of 24 bits is generated from the generator polynomial
G(X) described below.
G(X) = (1 + X) P(X) Eq. 22
P(X) is a primitive and irreducible polynomial given by the following equation.
P(X) = X 23 + X 17 + X 13 + X 12 + X 11 + X 9 + X 8 + X 7 + X 5 + X 3 + 1 Eq. 23
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OD SIS ICD, Issue 1, February 2010
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