National Communications System NCS ESF

1
National Communications System (NCS)ESF 2
Training ConferenceLAND MOBILE RADIO
SYSTEMSANDHOW TO RESTORE THEM
Major Curtis Bowers Plaquemines Parish Sheriffs
Office cbowers_at_ppso.net 504-392-1652 June 21,
2007
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Class Topics

• Types of Radio Systems
• Simplex
• Trunking
• APCO Project 25
• Frequencies
• Getting a system back online
• Radio gateway devices

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Different Types of Radio Systems

• Conventional Systems
• Simplex Operation (Radio-to-Radio)
• Repeater
• Trunking Systems
• Single Site
• Multicast
• Simulcast
• Conventional
• Digital

4
Conventional Systems

• Simplex Operation
• Transmissions are made over the same frequency

Transmissions are from radio to radio no system
infrastructure needed
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Conventional Systems

• Carrier Squelch - open to interference
• Private Line Code keeps radio signals on same
  frequency from keying into radio or opening the
  carrier squelch
• Interference audio is still present

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Conventional Systems

• What are the advantages of this type of system?
• Cost almost any radio will work, as long as
  frequency is correct
• Small number of users
• Small coverage area
• No infrastructure is needed

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Conventional Repeater Systems

• Repeaters boost transmission power for greater
  range
• Antennas are placed on towers for increase in
  coverage area

400
100 watts
5 watts
25 watts
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Conventional Repeater Systems

• Repeater systems improve portable and mobile
  talk-out and talk-in coverage
• A duplex system uses two frequencies. The radio
  transmits audio into the repeater and repeater
  sends out the audio at a higher wattage on a
  different frequency
• Antenna on a tower with a repeater gives a
  greater range
• Antenna on a tower with a pre-amp receive system
  increases talk-in coverage

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Trunking Systems

• Trunking systems consist of several repeaters
  controlled by computerized system
• System manages users, talkgroups, and repeaters

Repeaters
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Trunking Systems

• Trunking systems can be a single site or consist
  of multiple sites over large regions
• Each repeater has its own frequency and one of
  these repeaters is a control channel
• Control channel manages information to and from
  the users radios
• With this information, channels (repeaters) are
  assigned to users for radio traffic
• Control channel is always communicating with
  affiliated radios
• Affiliated radios send talkgroup (TG) info to
  system

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Trunking Systems
Voice Channel Request
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Trunking Systems

• There can be numerous talkgroups and users on
  this type of system
• Capacity is determined by number of channels
  (repeaters) the system has
• There can be numerous sites (towers) used on this
  type of system
• Size of system is limited to the number of
  frequencies the owner can obtain, the manufacture
  of the system, the version of system in service,
  and how much the owner can afford

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Trunking Systems

• Different types of multi-site systems
• Multicast
• The multiple broadcast of identical audio
  information on different frequencies from
  multiple, geographically separated sites
• Simulcast
• The simultaneous broadcast of identical audio
  information on the same frequency from multiple,
  geographically separated sites

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Trunking Systems
Multicast System Example
Site 2
Site 1
3
4
5
2
1
CC
VC
VC
CC
VC
Site 3
8
6
7
CC
VC
VC
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Trunking Systems
Site 2
Site 1
4
5
6
1
3
2
CC
VC
VC
VC
VC
CC
Site 3
7
8
Multicast cells could be combinations of sites in
what is also called a Simulcast configuration
CC
VC
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Trunking Systems
Simulcast System Example
Site 2
Site 1
3
4
5
6
7
8
2
1
3
4
5
6
7
8
2
1
CC
VC
VC
VC
VC
VC
VC
VC
CC
VC
VC
VC
VC
VC
VC
VC
3
4
5
6
7
8
2
1
CC
VC
VC
VC
VC
VC
VC
VC
Site 3
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Trunking Systems
Simulcast Seamless Coverage
Site 2
Site 1
1
1
2
3
4
5
6
7
8
2
3
4
5
6
7
8
CC
VC
VC
VC
VC
VC
VC
VC
CC
VC
VC
VC
VC
VC
VC
VC
1
2
3
4
5
6
7
8
CC
VC
VC
VC
VC
VC
VC
VC
Site 3
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Trunking Systems

• Trunking systems with multiple sites have a weak
  link in their operation links must go back to
  the master site
• Links can be T-1 circuits or microwave links
• Multicast sites that lose their links go into
  site trunking and no longer communicate with
  other sites
• In a simulcast system, only the prime site will
  continue to operate all other remote simulcast
  sites are off line until links are reestablished
• A simulcast cell can also go into site trunking

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Trunking Systems

• Analog operation
• Mix mode consisting of digital and analog
  resources
• APCO 25 systems digital only
• Digital is not a secure communication system,
  encryption is for secure communication

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Analog vs. Digital
Benefits of Digital Technologies Improved Audio
Quality
Digital
Good
Audio Quality

Analog
Poor
Signal Strength
Strong
Weak
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Frequency Issues

• License for frequencies to be restored or used
• Special Temporary Authorization (STAs) obtained
• Equipment must match frequency range of system
• Service equipment, software, and hardware needed
  to tune equipment to frequencies to be restored
• Types of equipment needing tuning for
  frequencies Combiners, duplexers, repeaters,
  tower top amp's, and radios

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Restoring a Communication System

• Survey what is left that still works or that can
  be put back in service
• What type of system will be initially put in
  service
• At tower sites you will need antennas, antenna
  mounts, antenna cable, cable connectors, tower
  climbing crew, and site master testing equipment

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Restoring a Communication System

• Determine how this equipment can be transported
  to the site
• If this is a remote site how will it be connected
  (linked) back to other sites microwave, phone
  circuits, or broadband satellite
• Locate or identify a vendor or service shop that
  can perform many of these task for you

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Restoring a Communication System

• Installing a new communication system
• What does the supported agency need
• What type of technology will be used
• What is best for the agency being supported, not
  what the vendors want to sell

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Radio Gateways

• How will this device help
• Will it even work with the system or systems
  being connected
• Get permission before connecting systems together
• Set the rules for how this gateway channel or
  talkgroup will be used

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Radio Gateways

• When a problem arises with this connection, a
  contact person must be available 24 hrs a day
• Not always the best way to connect groups of
  users together

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Questions

• Any questions welcome

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Contact Information

• Major Curtis Bowers
• Plaquemines Parish Sheriffs Office
• 8344 Hwy 23
• Belle Chasse, LA 70037
• 504-392-1652 office
• 504-812-9305 cell
• cbowers_at_ppso.net
• www.ppso.net