Automatic identification system

AIS OPERATES ON 161.975 MHz AND 162.025 MHz ( CHANNELS 87 & 88, WITHIN THE MARINE VHF SERVICE ) ITS PART OF THE WORLD WIDE MARITIME SAFETY SYSTEM, PACKETS OF DATA ARE SENT BY THE VESSELS GIVING THEIR CALLSIGN,POSITION,COURSE AND DESTINATION ETC TO OTHER SUITABLY EQUIPPED VESSELS. SINCE DECEMBER 2004 ALL VESSELS OVER 300 TONS ARE COMPULSORILY FITTED WITH AIS.TO RECEIVE SUCH DATA ALL THAT IS REQUIRED IS A SCANNER RECEIVER, COVERING THE MARINE VHF BANDS AND SOME SOFTWARE. IMPROVED RECEPTION WILL BE ACHIEVED IF THE SIGNAL FROM THE SCANNER RECEIVER IS TAKEN FROM THE DISCRIMINATOR OUTPUT.ONE THING TO BEAR IN MIND IS THE EXPECTED RANGE OF THIS SYSTEM, IF THE NEAREST BIT OF OCEAN OR ESTUARY IS 200 MILES AWAY, FORGET IT AS VHF WILL NOT COVER THAT DISTANCE, EXCEPT IN EXCEPTIONAL CONDITIONS. ANOTHER BIT OF SOFTWARE IS DSC DECODER ,IT WILL DECODE NAVTEX MESSAGES AND H.F. AND VHF DSC ( DIGITAL SELECTIVE CALLING MESSAGES) IT WILL DISPLAY THE SOURCE ON A CHART.SHIP PLOTTER CHARTS ARE COMPATIABLE WITH THIS SOFTWARE ALSO.THE VHF DSC FREQUENCY IS CHANNEL 70 - 156.525 MHZ.

SOFTWARE	MODEM	DOWNLOAD SITE
SHIPPLOTTER	SOUND CARD	SHIP PLOTTER
DSC DECODER	SOUND CARD	DSCDECODER
DGPS	SOUND CARD	DGPS DECODER
AISMON	SOUND CARD	YAHOO

DGPS BEACONS CAN BE FOUND BETWEEN 250 KHZ AND 350 KHZ,THEY HELP ADD ACCURRACY TO GPS POSITIONING.SEE THE DIAGRAM AT THE BOTTOM OF THIS PAGE.

FOR MORE DETAILED INFORMATION ON THE AIS SYSTEM PLEASE REFER TO THE BELOW LINKS :-

SHIP STATIONS

458.5
2177.0      2189.5
4208.0      4208.5    4209.0
6312.5      6313.0    6313.5
8415.0      8415.5    8416.0
12577.5   12578.0   12578.5
16805.0   16805.5   16806.0
18898.5   18899.0   18899.5
22374.5   22375.0   22375.5
25208.5   25209.0   25209.5

COAST STATIONS

455.5
2177.0
4219.5     4220.0    4220.5
6331.0     6331.5    6332.0
8436.5     8437.0    8437.5
12657.0 12657.5   12658.0
16903.0 16903.5   16904.0
19703.5 19704.0   19704.5
22444.0 22444.5   22445.0
26121.0 26121.5   26122.0

THE FOLLOWING ARE SHIP FREQUENCIES PAIRED WITH COAST STATION FREQUENCIES,AND THESE ARE "FIRST CHOICE DSC " FREQUENCIES

4208.0 / 4219.5
6312.5 / 6331.0
8415.0 / 8436.5
12577.5 / 12657.0
16805.0 / 16903.0
18898.5 / 19703.5
22374.5 / 22444.0
25208.5 / 26121.0

2177.0 KHZ IS RESERVED FOR SHIP TO SHIP CALLING ONLY

A DISTRESS ALERT IS SENT ON THE DSC CHANNEL,BUT THE ACTUAL TFC IS CONDUCTED ON A RT OR NBDP FREQUENCY

THE DCS DE-CODER PROGRAMME REQUIRES A DECENT RECEIVER.ON MF/H.F. WITH USB SELECTED TUNE ABOUT 1700 HZ BELOW THE DESIGNATED FREQUENCY, WITH LSB SELECTED TUNE 1700 HZ ABOVE THE DESIGNATED FREQUENCY.ON VHF THE SYSTEM IS SLIGHTLY DIFFERENT, AND REQUIRES YOU JUST TO TUNE YOUR RECEIVER TO THE CORRECT FREQUENCY.FOR VHF DSC DECODING,THE SIGNAL SHOULD BE TAKEN FROM THER DISCRIMINATOR DIRECT TO THE PC LINE IN/MIC IN JACK SOCKET.A LOT OF RECEIVERS HAVE WHAT IS BECOMING A STANDARD SOCKET ON THE BACK WHICH YOU CAN CONNECT TO.SEE THE BELOW DIAGRAM.THE SHIPPLOTTER PROGRAM REALLY REQUIRES THE OUTPUT TAKEN FROM THE DISCRIMINATOR CLICK HERE FOR FURTHER INFORMATION.

IF YOU HAVE A SPARE RECEIVER,USE IT TO MONITOR YOUR LOCAL VTS/TUG/VESSELS ON VHF AS WELL AS WATCHING THEM BEING PLOTTED ON YOUR SHIPPLOTTER CHARTS.

*CHANNEL 6*	*INTERSHIP*
*CHANNEL 8*	*TUG / SHIP*
*CHANNEL 9*	*AVONMOUTH RADIO*
*CHANNEL 10*	*TUG*
*CHANNEL 11*	*BRISTOL CITY DOCKS*
*CHANNEL 12*	*BRISTOL VTS*
*CHANNEL 13*	*SWANSEA/SHARPNESS/....ALSO BRIDGE COMMUNICATIONS*
*CHANNEL 14*	*SWANSEA/AVONMOUTH PORT OPERATIONS/BRISTOL CITY DOCKS*
*CHANNEL 16*	CALLING ETC
*CHANNEL 12/14/16*	*ROYAL PORTBURY DOCK RADIO*
*CHANNEL 17*	*SHARPNESS PIERHEAD*
*CHANNEL 18*	*CARDIFF*
*CHANNEL 23*	*SWANSEA/MILFORD HAVEN COASTGUARD*
*CHANNEL 37*	*MARINA CHANNEL*
*CHANNEL 67*	*ILFRACOMBE*
*CHANNEL 69*	*SERVERN VTS/SWANSEA TUGS*
*CHANNEL 71*	*SWANSEA TUGS*
*CHANNEL 72*	*TUG / SHIP*
*CHANNEL 73*	*PRINCE STREET BRIDGE/NETHAM LOCKS/BRISTOL HARBOUR*
*CHANNEL 74*	*SHARPNESS BRIDGE*
*CHANNEL 80*	*PORTISHEAD MARINA/BRISTOL MARINA*
*CHANNEL 86*	*SWANSEA/MILFORD HAVEN COASTGUARD*

DOES THE ABOVE ANTENNA WORK? ......AFTER USING IT FOR A COUPLE OF WEEKS AND COMPARING IT WITH A WHIP MOUNTED AT THE SAME HEIGHT, I HAVE TO SAY ITS A TREMENDOUS IMPROVEMENT. I WAS ONLY RECEIVING THE OCCASIONAL MESSAGE FROM SHIPS DOWN IN AVONMOUTH ( ABOUT 7 MILES AWAY,OVER A DIFFICULT PATH ) NOW I RECEIVE MESSAGES FROM SHIPS OUT IN THE BRISTOL CHANNEL TO A DISTANCE OF ABOUT 20 MILES.

HINT .. IF YOU ARE FEEDING AIS SIGNALS INTO THE SERIAL PORT ( USING THE EXCELLENT NASA A.I.S ENGINE FOR EXAMPLE ) REMEMBER ( DEPENDENT ON YOUR COMPUTER BEING FAIRLY "POWERFUL" )YOU COULD STILL RUN THE DSC PROGRAM AT THE SAME TIME WITH THE INPUT FROM YOUR RECEIVER FED INTO THE SOUNDCARD ......WINDOWS XP WILL ALSO SUPPORT MULTIPLE SOUND CARDS.

	http://www.navcen.uscg.gov/enav/ais/default.htm
	http://home.wxs.nl/~pa3esz/ais/index.html

	http://www.sailwx.info/maps/shipplotter.phtml?width=800&height=600&lat=52&lon=2&radius=50
	http://emit.demon.co.uk/map2.