MComm Ch7 - 1

1
Long Range Communications
Satellite Phones and Radios
MF/HF SSB Radio
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MF/HF SSB Radio
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MF/HF Overview

• Basic Transmitter and Receiver
• AM Transmitter and Receiver
• SSB Transmitter and Receiver
• MF/HF Antennas
• MF/HF Licensing
• MF/HF Operations
• Summary

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• Basic Transmitter
• and
• Basic Receiver

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Basic MF/HF Transmitter
Medium Frequency / High Frequency Transmitter

• Audio - 300 to 3,000 Hz
• DC - 12 to 14 VDC _at_ 30A

RF - 1.6 to 27.5 MHz Heat a few watts
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• AM Transmitter
• and
• AM Receiver

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AM Transmitter
(Amplitude Modulation)
Variable Oscillator
Frequency Multiplier
RF Amplifier
(Frequency Selection)
Modulator
(Mike)
PTT not shown
Modulator varies voltage to RF Amplifier
(Power)
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Amplitude Modulation

• Inputs (examples are shown below)
• 1 kHz (audio)
• 10 MHz (RF)
• Outputs
• 1 kHz (audio in)
• 9.999 MHz (10 MHz 1 kHz)
• 10 MHz (carrier in)
• 10.001 MHz (10 MHz 1 kHz)
• Amplitude of sidebands (9.999 and 10.001 MHz) is
  proportional to audio volume
• Frequency of sidebands (9.999 and 10.001 MHz)
  differ by audio frequency (1 kHz)

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Amplitude Modulation
Amplitude vs Time
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Frequency Modulation
(Review)

• Input
• 1 kHz (audio)
• 150 MHz (RF)
• Output
• 150 MHz (/- 25 kHz)
• Carrier shift (/- 25 kHz) is proportional to
  audio volume
• Rate of change, above and below carrier, is the
  same as the modulating audio frequency (1 kHz)

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AM TX Differences from FM TX

• Modulator Power
• AM requires lots of power (50 of RF Amp)
• FM requires very little power
• Efficiency
• AM (Poor)
• Carrier frequency carries no intelligence
• Duplicated intelligence in each sideband
• 100 watt transmitter
  has 25 watts of intelligence in
  one sideband
• FM (Good)
• Has all intelligence in carrier
• 100 watt transmitter
  has
  100 watts of intelligence

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AM Receiver
(Antenna)
(Speaker)
aka Envelope Detector
Audio Amplifier
IF Amplifier
RF Amplifier
Mixer
Demodulator
(Volume Control)
Local Oscillator
(Frequency Selection)
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AM RX Differences from FM RX

• AM Receiver does NOT have a limiter
• Need changes in amplitude to get audio volume
• Will get noise on weak signals
• No squelch control
• AM IF bandpass is narrower
• AM IF (typically 455 KHz) /- 3 KHz
• FM IF (typically 10.7 MHz) /- 5 KHz
• AM does NOT have a capture effect
• May hear two signals (stations) at once
• AM Demodulator
• Volume is derived from signal amplitude
• Frequency is derived from how far sideband is
  from carrier

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• SSB Transmitter
• and
• SSB Receiver

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SSB Transmitter
(Single Sideband Modulation)
Linear Amplifier
Balanced Modulator
Filter
Mixer
(Mike)
Variable Oscillator
Carrier Oscillator
(Frequency Selection)
PTT not shown
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SSB Modulation

• Inputs
• 1 kHz (audio)
• 10 MHz (RF)
• Outputs
• 10.001 MHz (10 MHz 1 kHz)
• Amplitude of upper sideband (10.001 MHz) is
  proportional to audio volume
• Frequency of sideband (10.001 MHz) is derived
  from audio frequency (1 kHz)

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SSB Modulation
Amplitude vs Time
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SSB TX Differences from AM TX

• Only transmits Upper Sideband
• No carrier
• No lower sideband
• 6 db more efficient (for same power transmitter)
• All intelligence resides in one sideband
• Uses half the bandwidth

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SSB Receiver
(Antenna)
(Speaker)
aka Product Detector
Audio Amplifier
IF Amplifier
RF Amplifier
Mixer
Demodulator
(Volume Control)
Local Oscillator
Beat Frequency Oscillator
(Frequency Selection)
(Clarifier)
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SSB RX Differences from AM RX

• IF amplifier bandwidth
• AM is 6 kHz wide
• SSB is 3 kHz wide
• 3 db advantage to SSB (half the atmospheric
  noise)
• Adds beat frequency oscillator
• Takes place of carrier that is NOT transmitted
• Clarifier is used to make voices sound human
• SSB demodulator
• AM is envelope detector
• SSB is product detector

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SSB Transceiver

• Transmitter and receiver are integrated into a
  single package

4.6 x 11.5 x 12.4 17.7lb
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MF/HF Antennas

• Power Boat Antennas
• Sail Boat Antennas
• Antenna Tuner
• Counterpoise
• Transmission Line

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Power Boat Antennas

• 23-foot fiberglass antenna
• Metal antenna inside fiberglass cover
• Requires
• Intermediate support
• Heavy-duty mount
• Antenna tuner

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Real Fiberglass Antennas

• Actually fiberglass insulated metal antennas

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Sailboat Antennas

• Normally an insulated backstay antenna
• Minimum of 23 feet long
• Requires
• Backstay insulators
• Antenna tuner

10 insulator for ¼ wire has 12,000 lbs breaking
strength
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Real Backstay Antennas
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Antenna Tuners

• Matches transceiver to antenna
• Should be near antenna
• Manual and automatic

9.1 x 13.4 x 3/1 6lb
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Counterpoise (ground plane)

• Recommend 100 sq ft of counterpoise
• Power boats
• Copper foil from antenna tuner to engines
• Sailboats
• Copper foil from antenna tuner to keel
• Install copper foil inside below waterline
• Bow to stern
• On both sides
• One or two runs
• Connect to antenna tuner

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Transmission Line

• Coax from transceiver to antenna tuner
• RG-213 (50?)
• PL-239 male connectors
• Waterproof exposed RF connectors
• High voltage wire from antenna tuner to base of
  antenna
• GTO-15 (rated at 15,000 volts)
• Want the shortest length possible

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MF/HF SSB Installation

• Biggest fault with most marine MF/HF SSB
  installations is lack of sufficient counterpoise

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MF / HF Licensing

• Operator License
• Equipment License
• Illegal Operations

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Operator License

• FCC license required to transmit on MF/HF
• Restricted Radiotelephone Operator Permit
• On rules, regulations and procedures
• Lifetime license
• More details in chapter 5

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Equipment License

• FCC Ship Station License
  for MF/HF Transmitter (transceiver)
• Ten year license
• More details in Chapter 5

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Illegal Operations

• Using amateur radio transmitters
  on marine MF/HF frequencies
• even if operator has a Restricted Permit
• Modifying marine MF/HF transmitters to operate on
  amateur radio frequencies
• It is legal to use marine MF/HF transmitters on
  amateur radio frequencies
• provided operator has amateur radio license
• equipment is unmodified

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MF/HF Operations

• Why MF/HF?
• Who can you communicate with?
• Frequency selection
• Ship-to-Shore stations
• Receive only services

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Why MF/HF?

• Communications beyond VHF range
• Advantages
• Can broadcast to many stations at same time
• No usage cost
• unlike satellite communications
• Disadvantages
• Selecting right frequency is NOT easy
• Communications are NOT private
• Subject to atmospheric noise and fading
• Equipment cost greater than satellite phone

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With whom can you communicate?

• MF/HF voice comm similar to VHF-FM voice
• Recreational boaters
• Safety and operational needs
• Commercial Ships
• Safety and operational needs
• Ship-to-Shore Stations
• Safety and operational (USCG)
• Personal and social
• ShipCom
• SailMail

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Frequency Selection
(Review)

• Marine bands 2, 4, 6, 8, 12, 16, 18, 22 25 MHz
• 2 MHz day at least 100 nm, more at night
• 4 MHz day 20 to 250 nm, night 150 to 1,500 nm
• 8 MHz day 250 to 1,500 nm, night 400 to 3,000 nm
• 12, 16, 18, 22 25 MHz thousands of miles
• Emergencies
• 2182.0 kHz voice
• 2187.5 kHz DSC
• MF ground wave out to 250 miles
• HF sky wave over 500 miles

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Ship-to-Shore Stations

• Covered in Appendix C
• USCG
• ShipCom
• SailMail
• Covered in Appendix D
• Pactor HF data Modem

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USCG 24/7 MF/HF Stations
Communications Area Master Stations

• Master Station Pacific
• NMC _at_ Point Reyes, CA
• NOJ _at_ Kodiak, AK
• NMO _at_ Honolulu, HI
• NRV _at_ Guam (not shown)

• Master Station Atlantic
• NMN _at_ Chesapeake, VA
• NMF _at_ Boston, MA
• NMA _at_ Miami, FL
• NMG _at_ New Orleans, LA

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ShipCom HF Locations
ShipCom Operations Center 24/7 in Mobile, AL

• West Coast Radios
• KLB _at_ Seattle
• KNN _at_ Marina Del Ray

• East Coast Radios
• WLO _at_ Mobile
• WCL _at_ New Jersey

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SailMail HF Locations
SailMail provides HF email gateways

• West Coast
• WQAB964 _at_ San Diego, CA
• WHV861 _at_ San Louis Obispo
• WRD719 _at_ Palo Alto, CA
• WHV382 _at_ Friday Harbor, WA

• East Coast
• XJN714 _at_ Nova Scotia
• KZN508 _at_ Rockhill, SC
• WPUC469 _at_ Daytona, FL
• WPTG385 _at_ Corpus Christi

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NOAA Weather

• Transmitted by USCG
• Transmits NOAA / NWS weather forecasts
• MF and HF voice
• HF Facsimile
• HF Teletype (SITOR modem)
• Details in Appendix E

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WWV

• Located at Ft. Collins, CO (N of Denver)
• Broadcast on 2.5, 5.0, 10.0, 15.0 20.0 MHz
• US frequency and time standard

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News

• Near shore commercial AM
• 535 to 1700 kHz
• Voice of America (short wave)
• BBC (short wave)
• Good short wave band is 9.4 to 9.9 MHz

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MF/HF Summary

• Marine MF/HF SSB systems consists of
• Transceiver, antenna tuner, antenna
  counterpoise
• For use beyond VHF line-of-sight communications
• Requires a knowledgeable operator
• SSB is more efficient than AM
• MF/HF antenna requires
• Antenna tuner
• Counterpoise
• MF/HF requires two licenses
• Equipment (Ship Station)
• Operator (Restricted Permit)

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Satellite Communications
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Overview

• History
• Advantage of Height
• Orbits
• Architecture
• Communications Systems
• (Phones, email and high end)
• Specific Systems
• (technical details)
• Summary

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History

• 1945 Arthur Clark Extra-Terrestrial Relays
• 1955 John Pierce Mirror in Space
• 12 Aug 1960 ECHO I
• 1962 TELSTAR and RELAY
• 1982 - INMARSAT

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Advantage of Height

• D (in nautical miles) 1.32 v h (in feet)
• Height Range (in nm) Remarks
• 100 feet 12.5 Antenna tower
• 250 feet 19.8 High antenna tower
• 100 miles over 900
• 500 miles over 2,000 Low Earth Orbit (LEO)
• 22,240 miles over 13,500 Geosynchronous
• Earth Orbit (GEO)
• GEO can see 1/3 of Earths surface!

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Orbits

• Low Earth Orbit (LEO) constellation
• 25 to 75 satellites in orbits from 450 to 900 nm
• Period around 100 minutes (from 500 miles)
• Each satellite is visible for approx 15 minutes
• Geostationary Earth Orbit (GEO) constellation
• 4 satellites in stationary 19,330 nm orbits
• Period 23 hours and 56 minutes
• The same 1 or 2 satellites are always visible

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Architecture

• Bent Pipe
• Store and Forward
• Switched with Cross Links

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Bent-Pipe

• Communications satellite is a real-time radio
  relay
• All smarts are on the ground
• Dumb satellite, transmits all data that it
  receives
• User Ground Station have to see same satellite
• At the same time
• Latency is waiting for a satellite to come into
  view

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Store-and-Forward

• Comm satellite is a store-and-forward radio relay
• Can save received data until it sees a ground
  station
• Most smarts are on the ground
• Satellite transmits all that it receives to the
  ground station
• User and ground station have to see same
  satellite
• But NOT at the same time may be minutes of
  latency

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Switched or Cross-linked

• Communications satellite decodes switches data
• Smart satellite
• Considerable smarts still on the ground
• After decoding data, the communications
  satellite
• Switches data to another satellite user
• Switches and cross-links data to another
  satellite
• Switches data to ground station

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General Systems

• Satellite phones
• Email only (packet data)
• High end data and voice

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Specific Systems

• Iridium (LEO Satellite Phone)
• IsatPhone (GEO Satellite Phone)
• SkyMate via Orbcomm (LEO data / email)
• Inmarsat (High end system)
• mini-C (GEO data / email)
• mini-M (GEO voice and data / email)

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Satellite Phone - Iridium

• 66 LEOs at 420 nm
• Orbits 86.4º with 100 min period
• Weight 1,500 lbs
• Voice and data at 2400 bps
• Switching in sky (with cross links)

13.2 oz
1,500 lbs
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Iridium - 2

• Worldwide coverage
• (8816 or 8817) 8-digit phone number
• Purchase (or lease) handset, service from VAR
• Antenna must be outside
• Pointed straight up
• With clear view of sky
• Some installations use external antenna
• 9505 handset gives 3.8 hr TX 35 hr standby
• Cost
• Handset 1,400
• 20 a month plus 1 to 1.50 per minute

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Iridium Variants
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Satellite Phone - IsatPhone

• Satellite Phone service by INMARSAT
• Only from 4th generation GEO I-4 satellites
• 12,000 lbs and 13 kW of power
• Dual mode phone
• 2400 bps satellite phone
• 9600 GSM cell phone

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IsatPhone - 2

• Currently coverage only in Indian Ocean
• Purchase (or lease) handset, service from VAR
• Antenna must be outside
• Pointed straight up
• With clear view of sky
• Handset give 2.7 hr TX and 42 hr standby
• Cost
• Handset 600
• 1 per minute

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IsatPhone Coverage

• July 07 Coverage
• Region in brown
• From I-4 F1 (64º E)
• By end of 2009 expect global coverage
• 40º N to 40º S
• from all 4 I-4s

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Email - SkyMate

• SkyMate is a VAR for Orbcomm
• Orbcomm has 29 LEOs at 515 miles
• 4 orbits and 28 satellites inclined at 45º
• 1 orbit in near-polar orbit
• Weight 92 lbs, power 160 W
• Data packets (email) only
• 2400 bps up
• 4800 bps down
• Bent Pipe architecture

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SkyMate - 2

• SkyMate provides
• Email delivered as voice or fax
• Position reporting (requires interface with GPS)
• Customized weather forecasts
• Remote vessel monitoring (extra HW and SW)
• Fixed installation
• External antenna
• User provided PC and GPS
• Cost
• HW and SW start at 1,200
• 18/month for 8,000 characters

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Orbcomm/SkyMate Coverage

• Current (2007) coverage in brown
• Planned late 2008 coverage addition in blue

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SkyMate Installation

• Antenna needs good view of sky
• Located within 30 foot coax run of transceiver

GPS (user supplied)
pig tail adapter
SkyMate 100 Transceiver
GPS data cable
coax
PC (user supplied)
12 VDC
serial data cable
Main harness assy.
Message indicator light
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INMARSAT mini-C and mini-M
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Email INMARSAT mini-C

• 4 Bent Pipe GEOs at 19,330 nm
• E-mail packet data at 600 bps
• Also X.25 protocol from PC to PC
• Requires user-provided PC (RS-232 interface)
• Unstabilized antenna (6 inches high 2.4 lbs)
• Cost
• eTRAC terminal (HW and SW) 2,000
• 1 per character

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INMARSAT mini-C Coverage

• Basically 70º north to 70º south

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mini-C Installation

• Antenna needs good view of sky
• PC is user-provided

User provided PC with eTRAC software
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Voice Email INMARSAT mini-M

• 4 GEOs at 19,330 nm
• Voice and Email packet data at 2400 bps
• Also X.25 protocol from PC to PC
• Requires user-provided PC (RS-232 interface)
• 3-axis stabilized antenna (11.5-inches high 11
  lbs)
• Cost
• Tracphone 252 (HW and SW) 4,700
• 1.49 per minute with no monthly fee

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INMARSAT mini-M Coverage

• mini-M coverage is in blue (from spot beam
  coverage)
• Some mid-ocean gaps south of the equator
• Red dots are Land Earth Stations

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Summary

• Architecture
• Bent Pipe
• Store and Forward
• Switched and cross-linked
• Satellite Phone
• Iridium
• IsatPhone (today Indian Ocean only)
• Scheduled for worldwide by end of 2009
• Email
• SkyMate (value added to Orbcomm)
• Inmarsat mini C and mini M (high end users)

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