VHF HANDBOOK Flashcards
Who would you contact using DSC (digital select calling)
Individuals, groups or all stations
What are the basic differences between MF HF and VHF
HF can bounce of the ironosphere ,Travel globally
MF can follow the curvature of the earth, travel hundreds of miles
VHF travels in straight lines (lines of sight) travel tens of miles depending on height of sending and receiving antennas
What the channels allowed for on board communications
15 and 17
Low power only (1w)
If you want to repeat a sentence name or number what would you say
If you want them to repeat a message what would you say
I say again
Say again
Hand held radio specifications
Smaller than a fix radio usually run of a rechargeable battery
With a short stubby antenna
Whilst there is a distress call going on what must you do
Maintain radio silence
How long would you push the emergency /distress button for
5 seconds or just a push then select what the emergency is (ie sinking) then push for 5 seconds to send. depending on type of radio
How could the coastguard announce that radio seelonce is over
Seelonce feenee
If you heard a distress massage what would you do
Wait five minutes if you don’t hear a reply from the coastguard reply your self then try to rely the message on to the coastguard
What decibel antenna is best for cannoo
A yacht
And a motor boat
Canoe 1.5db
A yacht 3db
Large ship 6db
What is the difference between simplex and duplex channels
Example channel 80
Simplex only one person can talk at a time
Duplex uses two channels so both can talk and hear (ie link calls)
Channel 80 coast station (marina) is a duplex channel but as we only have one antenna it’s exactly like using a simplex channel
If you call a UK marina with a “USA radio” the marina will hear you but you won’t hear them reply as in the USA Channel 80 is a simplex channel
After sending a DSC mayday what would you do next
Go to channel 16 to give a voice mayday call
Basics of marine VHF antennas
Vertical is best as the power comes out of the sides (so it concentrates more on the horizon)
Slightly shorter than half the VHF radio wave so about 93
3dbi is best for sailing yachts as it gives twice as much power towards the horizon and is tolerant of heel and pitch
6dbi gives twice as much power towards the horizon as a 3db antenna but power drops off if its tilted so recommended for motorboats (only if it can be mounted upright)
A 1.5dBi antenna is not badly effected by being used at an angle so is used for portable radios
What two UK government body’s are concerned with marine VHF
And fines
Ofcome office of communications technical issues and radio regulations ie is a radio licensed
MCA. Maritime coastguard agency deals with matters regarding SOLAS (has the vessel got the right equipment and is the operator appropriately qualified)
Fines up to £5000 up to 6 months prison and loss of equipment
What is modulation
Simplest form switching on and off (morse code)
More sophisticated form = the physical vibration of air converted by microphone into electricity
What’s the maximum time (apart from distress and safety calls) should you use channel 16
1 minuet
What’s the first thing you would do before making a call
Listen to check we are not interrupting an other call first
What sort of radio check “replies” could you give
Loud and clear
Broken
Weak
Distorted
If you buy a new VHF radio what’s the first thing you should check in the settings
That it is set to INTERNATIONAL not USA
What’s the four main groups types of messages that can sent by VHF
- Distress,Urgency,Safety
- Routine
- Public correspondence, or link calls
- On board communications
What channel is used for small craft safety
67
What type of radio is related to a MMSI with starting with 2359
A UK Hand held
What would a Group of boats MMSI start with
A single 0
Example = 023200345
Power of VHF radios
1w = low 5 to 10 miles (should use if poss) 25w = high 60miles or more
Portable radios 1w and 3w or 6w
If you hear a call and are not sure it’s for you what would you do
Don’t answer it (in case you interfere with someone else’s call)
If it is for you the station will try again
What is the channel for port operations
And could you use this to talk to another ship
Channel 12 is port operations and it would be dangerous and illegal to use for chat
How would the coastguard no he is being called by a portable radio
The callsign would be T then just numbers
Under uk law what does voluntary fit mean
Owners have “chosen” to conform to the codes of practice for small commercial craft
What must you remember when calling the coastguard on the Solent
Normally you would use channel 16 to call the coastguard but on the Solent you use channel 67
Radio frequency basics
VHF AND UHF
VHF and UHF
not good at bending over hills or over the horizon nor are they bounced back by the ionosphere so used for local broadcasting tv and communications
Recharging battery’s
Recharge NiCads only when flat
Top up rechargeables whenever you can
Don’t over charge rechargeables (particularly Lithium Lon)
Don’t recharge alkalines or Lithium’s
How would you call a emergency
Mayday mayday mayday this is redwing redwing redwing
Give call sign MMSI / mayday redwing give call sign and MMSI again/Give position / say what the problem is \ you need immediate assistance/how many on board/ describe boat length colour /Over
How do you determine the antenna’s VHF horizon (in miles)
Approximately 3x the square root of its height in metres
Two radios will be in range when their horizons overlap
Who would have a MMSI starting with 00
Coastguard
If you ask someone to wait what els should you do
Tell them how long they may expect to wait
What are the Types of stations that use Marine VHF
Ship stations (any type of vessel) Coast stations Rescue coordination organisations Pilot, VTS and port stations harbour masters and marinas, yacht clubs Aircraft stations
Battery lead acid
Lead acid - heavy and bulky but fully rechargeable (standard use on boats for starting and domestic)
Heavy duty car battery’s deteriorate when discharged by 30%
Deep cycle battery’s don’t but don’t provide such large currents (for starting)
Acid gel battery’s are less susceptible to spills but reduced ability to produce high currents or rapid charging
“Leisure battery’s are a good compromise”
If somebody’s calling you (redwing) and can’t make out their name
or call sigh how would you reply
Station calling redwing this is redwing over
What channel would you use for uk marina
Channel 80
Semi duplex channel so listen first a little longer as you only hear one way conversation between the marina and another ship station
(you use normally as simplex channel) but others will only hear one way
How long after calling would you wait for reply before calling again
And how many times before giving up
When can you start again
2 minutes
3 times before giving up
Wait at least 3 mins before starting again
Battery’s Lithium lon
Rechargeable (Expensive)
Store more power but susceptible to over charging
What frequency do marine VHF Radios use
156.00MHz to 162.025MHz
When would you use a pan-pan call
Urgent Safety but not in immediate danger
If your going to spell something what would you say
I spell
(then use the phonetic alphabet)
What UK private channel is allocated to marinas and yacht clubs
37 also known in the UK as channel M
Are you allowed to communicate with a private radio base from shore
No
(Must be a licensed coast station)
No telling the wife to put the kettle on on the Spair radio in the house
Are Link calls still operating in the uk (calls from VHF Via coast station to telephone network)
No
If you require part of a message repeating what would you say
All before
or all after
If you want them to repeat a message back (to confirm they heard you) what would you say
Read back
Can you transmit in duel watch mode
No not normally though some can check instructions
What two licenses do you require to have a radio on board
Portable radio basics
A ship radio licence = covers all radios onboard issued by ofcom valid 10 years must be carried on board you get a callsign and a MMSI number
An Authority to operate = SRC COMPETENCE passed covers VHF and radiotelephony
LRC Passed covers VHF,HF,MF and radiotelephony and satellite communications
A Portable ship radio licence = licensee can have available for use 1 VHF portable maritime radio also 1 PLB / and or 1 EPIRB
A Portable license is issued to a person not the ship and can be used on multiple vessels
Who must approve the radio type equipment
MED OR RED
MED = marine equipment directive RED = radio equipment directive
The general principle that the radio equipment dose its job without being dangerous or causing unnecessary interference
Declaration of conformity to be issued by the manufacturer with CE label
When would you use your radio on high setting (25w)
After you have tried low setting (1w)
So you don’t interfere with other peoples transmissions
Battery lithium
Lithium = not rechargeable but have a long shelf life so ideal for emergency equipment as EPRIRBs
(like alkaline produce 1.5v per cell)
Why is channel 70 the odd one out
Channel 70 is used for the transmission of digital data in connection with DSC (Digital select calling)
All the others are used for radiotelephony.
70 must never be used for voice transmissions
If you are going to contact someone close to your boat what power would you use
Set radio to low (1 Watt)
Why is channel 16 significant
And it’s connection with channels 75 and 76
Channel 16 is designated as the distress,safety and calling channel
75 and 76 are the closest to it and only allowed 1w power and are only available for port operations and onboard communications
What is the squelch noise from the radio
Weak signals, static , atmospheric noise
Turning the squelch up will eliminate unwanted noise
Battery Alkaline
Alkaline = not normally rechargeable (Duracell) 1.5v per cell
If someone says there is traffic what does this mean
Line is being used (Talking on it)
What would UK ship radio MMSI’s start with
232,233,234 or 235
If a message is repeated back incorrectly what would you say
And if it was correct
Wrong
Correct
What channels are reserved for port operations
11, 12 and 14
Battery’s NiCad
NiCad can withstand thousands of charge/discharges but loose charge over time and due to recharging when not fully discharged (suffer from memory effect) lower voltage than alkaline so not all equipment is compatible them
If you received a distress emergency alarm on a hand held how would stop the noise
Push enter
What are the types of communication in the maritime mobile service
Distress,urgency,and safety communications
SAR(search and rescue)communication
Public correspondence
Port operations and ship movement services
Intership communications
On board communications
How can MMSI numbers be entered
From a directory or manually
Battery’s NiMH
Nickel Metal Hydride
Rechargeable and higher capacity than NiCad and suffer less from memory effect
but also low voltage and incline to discharge when not in use
What does the MMSI number for a group of boats start with
0
What does the MMSI number start with for coast stations
00
What does uk hand held radios with DSC MMSI numbers start with
2359
How are radio communications categorised
By their content Routine Safety Urgent Distress
What is unique to each vessel
Call signs and MMSI numbers
What ship to ship stations could you transfer to after initial coms on channel 16
6
8
72
77
What channels are used for
maritime safety information (UK)
(These are duplex channels)
62
63
64
Radio frequency basics
VLF AND LF
VLF AND LF
Are better for long distance broadcasting as they are more susceptible to diffraction and refraction (such as and water)
Radio frequency basics
MF
MF
Less good at diffraction so used for medium range as aeronautical radio beacons,regional broadcasting and medium range communications
Radio frequency basics
HF
HF
Not good at bending over the atmosphere but
Reflect of the ionosphere and bouncing back to ground level
So better for world wide broadcasting and communications
What is private channel 0 used for
UK Search and rescue services
Who do you register a EPIRB with
MCA = marine coastguard agency
