Wavecom W-SPECTRA (Automatic Monitoring System) V1.1.0 - Manual (Page 101)

WAVECOM Monitoring System W-SPECTRA, W-SPEED Manual V1.1.0 Transmission Modes
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91
Normal Inverse Normal Inverse Normal Inverse Normal Inverse
073 506 246 523 431 723 664 311
074 174 251 165 432 516 703 565
114 712 252 462 445 043 712 114
115 152 255 446 446 255 723 431
116 754 261 732 452 053 731 155
122 225 263 205 454 266 732 261
125 365 265 156 455 332 734 371
131 364 266 454 462 252 743 654
132 546 271 065 464 026 754 116
134 223 274 145 465 331
143 412 306 071 466 662
145 274 311 664 503 162
152 115 315 423 506 073
DGPS
DGPS (Differential Global Positioning System) data is mainly transmitted in the low frequency band e.g.,
285 - 315 kHz. It is a correction signal for GPS receivers, and is used to increase the accuracy of the sat-
ellite-based GPS signal. DGPS is based on the transmission of correction data by a reference station, the
position of which has been determined with high accuracy by traditional position-finding measurements.
With the correction data, an absolute accuracy to within 4 meters can be achieved.
Parameter Value
Frequency range HF
Operation modes Broadcast FEC
Modulation Minimum-Shift-FSK
Symbol rate 100.0 and 200.0 Bd
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-5
Transmissions use MSK (Minimum Shift Keying) with speeds of 100 or 200 baud.
DGPS has been implemented according to RTCM SC-104 "Recommended Standards for Differential
Navstar DGPS Service" v.2.0, Jan. 1990.
 These messages are decoded: 1, 3, 7, 9, 13, 16.
 These messages are NOT decoded, but their type is indicated: 2, 4, 5, 6, 8, 10, 11, 12, 14, 15,
17, 60-64.
 Compared to M.823-2 messages 4 and 5 are not decoded by my implementation neither are the
equivalent GLONASS.
DGPS data, which is formatted according to RTCM v.2.0 or 2.1, is continuously transmitted in frames con-
sisting of a varying number of data words. The two first words of each frame contain the reference station
id, the message type, a sequence number, the frame length and the health of data. A data word has a
length of 30 bits: 24 data bits and 6 parity bits. The last two bits of a word are used as an EXOR function
for selected bits of the succeeding data word. The value of the last bit indicates whether the next data
word is sent with inverse or normal polarity.