Article Figures & Data
Figures
- FIGURE 1
The Automatic Identification System (AIS) message structure (ITU-R, 2014)
- FIGURE 2
The VDE-TER message structure (IALA, 2019)
- FIGURE 3
The relation between the determined distance accuracy and the received signal level
- FIGURE 4
The relation between the determined distance accuracy and the signal to noise level [The Cramer-Rao lower bound (CRLB)]
- FIGURE 5
The relation between the determined distance accuracy and AIS/VDES base station range for the base station antenna height 60 m ASL and ship antenna height 20 m ASL
- FIGURE 6
Test-bed transmitter diagram for the VDES transmission
- FIGURE 7
Test-bed receiver diagram for the VDES transmission
- FIGURE 8
Correlation peak found (100,000 samples) as an example for AIS. Correlation peaks for both AIS and VDES systems are also presented for comparison
- FIGURE 9
The distance calculated by the AIS R-Mode system compared with the distance determined by the GNSS with EGNOS
- FIGURE 10
Ferry route versus distance accuracy error for AIS system
- FIGURE 11
Distance error for the AIS R-Mode measurements
- FIGURE 12
Measurements of the signal-to-noise ratio (SNR) for AIS system
- FIGURE 13
The distance calculated by the VDES R-Mode system compared with the distance determined by the GNSS + EGNOS
- FIGURE 14
Ferry route versus the distance accuracy error for VDES R-Mode system
- FIGURE 15
Distance error for the VDES R-Mode measurements
- FIGURE 16
Measurements of the signal-to-noise ratio (SNR) for VDES R-Mode system
- FIGURE 17
RMS curves for all measurements with an enlarged graph showing the calculated RMS values for high SNR
- FIGURE 18
a) AIS spectrum, and b) VDES spectrum
Tables
Acc = 10 m AIS AIS AIS VDES BTS Ship LS = 80 LS = 300 LS = 968 LS = 1877 30 m 4 m 7.5 10.5 13.5 21.5 10 m 9.5 14.5 19 29 20 m 14.5 19 24.5 36 60 m 4 m 9.5 13.5 17.5 27 10 m 14 19 24.5 36 20 m 18.5 24.5 31 44 Error to be minimized Utilized measures Clock errors Rubidium disciplined oscillator Delay on the transmitter and receiver sides Calibration measurements; see below Error of the station’s position determination Position determined with a real-time kinetic (RTK) receiver Error of the ship’s reference position Reference ship’s position determined via GNSS + EGNOS Errors due to noise and interference Filters and LNA Location N 54° 31′ 45, 36″ E 18° 33′ 34,48″ Height of the antenna 28 m ASL Frequency of the transmitter 161.8375 MHz Antenna type Radmor 32812/1 Antenna radiation pattern Omni-directional antenna Antenna gain 2.15 dBi Cable and filters attenuation 8.5 dB ERP power 14.8 dBW Source of error Applicable for low SNR region Applicable for high SNR region Possible impact of residual clock errors yes yes Errors caused by the presence of the Hel Peninsula yes no Errors that can be caused by lack of EGNOS and/or high HDOP yes yes Ship’s speed too high yes yes Weather conditions yes yes Error resulting from passing the LOS distance (beyond the 42.4 km mark) yes no Sampling rate yes yes
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