Murmansk State Technical University (MSTU) Marine Academy. The prospects of GMDSS quality improvement in the Extreme North conditions

Transcription

1 The prospects of GMDSS quality improvement in the Extreme North conditions By Alexander Suslov Associate Professor of Navigation Department

2 Topics to be covered:. The peculiarities of GMDSS application in the Extreme North conditions 2. Overview of the present marine radio communication system development 3. Methods of interferences suppression in the marine radio communication systems 4. Prospective methods of interference suppression 5. Prospective radio equipment to be used during search and rescue operations at sea

3 . The peculiarities of GMDSS application in the Extreme North conditions Fig.. Methods of distress alert transmission in sea areas A A3 2

4 . The peculiarities of GMDSS application in the Extreme North conditions. The distress alerting is possible only by using COSPAS-SARSAT system and marine radio communication equipment of High Frequencies (HF) band 2. Heavy instability of HF radio channels parameters 3. Complex structure of interferences effecting the receivers of radio communication systems 3

5 . The peculiarities of GMDSS application in the Extreme North conditions F upper ionosphere; E middle ionosphere; D lower ionosphere; silent zone Fig.2. Propagation of HF radio waves, 2 radio waves propagating by double reflection from ionosphere; 3 radio wave propagating by single reflection from ionosphere; 4 radio wave with the frequency more than critical. 4

6 . The peculiarities of GMDSS application in the Extreme North conditions Typical effects occurring during the HF radio signal reception: radio-signal decay 2 mutual interference of receiving signals 3 the efficiency of radio communication depends on the hour, season, solar radiation intensity etc. 5

7 2. Overview of the present marine radio communication system development Radio communication performance criterion: () Fig.3. Typical GMDSS A4 ship radio installation Up-to-date radio communication systems provide condition () only in the following situation: (2) 6

8 2. Overview of the present marine radio communication system development In the Extreme North conditions inequality (2) often is not true. The significant shortcoming of telex terminals is that the validity improvement is achieved by the increasing of the time period required to receive the information! Fig.4. Validity securing of telex information receiving by radio channels 7

9 2. Overview of the present marine radio communication system development The main lines of GMDSS equipment development: ) The upgrading of radioelectronic systems components 2) Raising the automation level of the performing operations 3) The enhancement of the communication service range! None of the listed above methods is able to improve the quality of radio communication in the case of powerful interferences influence on the receiver 8

10 3. Methods of interferences suppression in the marine radio communication systems ) Suppression of the interferences with the structure which differs from the signal structure 2) Using directional aerials 3) The application of the signals with special structure Notes: ) Method is non-effective in the case when interference has the structure similar to the signal s one 2) Method efficiency is restricted in HF band 3) Method provides error detection but it s impossible to correct it 9

11 4. Prospective methods of interferences suppression. Adaptive signal procession Fig.5 Input and output signal of the adaptive filter 0

12 4. Prospective methods of interferences suppression. Adaptive signal procession Fig.6. Signal cleared from interferences by adaptive procession

13 4. Prospective methods of interferences suppression 2. Special radio signal procession at the receiver end Method purpose signal structure changing without any distortion of the containing information The method is to transform signal shape in such way that the considerable part of interference energy is concentrated outside of the signal frequency band Method efficiency power of interference is suppressed more than twice saving the signal power at the same level 2

14 4. Prospective methods of interferences suppression 3. Intelligent processing of the message distorted by interferences Fig.7. Telex message distorted by interferences Fig.8. Recovered telex message using intelligent processing 3

15 5. Prospective radio equipment to be used during search and rescue operations at sea the path of radar probing signal in standard conditions the path of signal reflected from the observed object in standard conditions 3 the path of radar probing signal in the case of radar signal decay Fig.9. Radar observation at sea in different conditions 4

16 5. Prospective radio equipment to be used during search and rescue operations at sea The inclusion of thermal radar in the marine radar complex: Fig.0. Output signals of thermal radar signal power is 0 % of the device internal noise power; 2 signal power is 30% of the device internal noise power. 5

17 Thank you for your attention!