Transcript P25 System Overview for Radio Train-the

P25 Trunked System Overview
for Radio User Train-the-Trainer
Training Session Notes
ECP####A
ECP3078A
Contents
What is P25?
M/A-COM P25 Terminal Equipment
Call Types
Unit ID’s
Call Processing
Emergency Calls
Group Scanning
ProScan
Terminology
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What is P25?
Interoperable digital radio system standard
Intended for all public safety LMR bands (VHF, UHF, and 800 MHz)
Developed Jointly by:
– TIA
– Association of Public-Safety Communications Officials (APCO)
– National Association of State Telecommunications Directors
(NASTD)
– Various agencies of the Federal government (FED) in the early 90’s
to improve spectral efficiencies.
TIA/EIA Standard in 1999. Under TIA/EIA-102
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Project 25 Benefits
Key benefits sought by the user community:
– Competitive procurement of equipment
– Interoperability of equipment
– Spectrum efficiency
– User-friendly operation equivalent to today's public safety equipment
and common across all bands, system configurations, services, and
manufacturers.
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Project 25 Features
Key voice features
– IMBE vocoder
– Group and Individual calls
– Telephone interconnect
– Emergency
– Encryption (DES, AES)
– Console dispatch
– Preempt
– OTAR (Over-the-Air-Rekeying) Packet switched IP backbone
– Full control of the system and radios
– Interoperability - network level and radio level
– Group, individual, emergency calling
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Some P25 System Basics
Each Radio:
– Unique Unit ID
– One or More Systems (sites)
– One or More Talk Groups (Group ID)
Talk Group:
– A ”Logical” Collection of Units
– Unique Group ID
Capacities:
– 16,777,216 Unit IDs
– 65,536 Group IDs
TRAINING
TRNG 1
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P25 Portable Radios
P7170
(System
Model)
P7150
(Scan
Model)
P7130
(Select
Model)
P5150
(Scan
Model)
P5130
(Select
Model)
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M7100 Mobile Radio
Hand-held
Controller
Scan
Control Head
System
Control Head
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P25 Terminal Features
P25 Group call transmission/reception
Talk group identification
Group call alert
P25 Individual call transmission/reception
Individual identification (PTT ID)
Emergency and Emergency Indication
Priority Scan
Carrier control timer (CCT)
Transmit lockout
Up to 256 conventional channel capacity
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Call Types
Voice Calls
– Group Calls
• Normal
• Emergency
• Announcement Groups
– Individual Call
• Unit to Unit
– System All Call
Radio displays Group and Caller ID for each call
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Unit Identification
Unit ID
– Uniquely identifies radio to system
– 24 Bits – 16,777,216 Possibilities (0 - 16,777,215)
– Only allow 1 – 9,999,999
– Must be programmed into radio
– Allows Individual Calling
– Allows Call Tracking
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Conventional vs. Trunked
Computerized Assignment of Channels
Trunked
Conventional
Service Counter
Service Counter
Service Employee
Customer
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Call Processing
Mobiles / Portables continuously monitor Control Channel
Operator makes selection, depresses PTT, and transmits a Channel
Request message
Channel Request received by Control Channel
System validates request against the Group and Unit databases
Control Channel responds with Working Channel assignment
Units switch to the assigned Working Channel
– Calling Unit is now ready to talk, caller can be advised by a grant
tone “beep” to start talking
– Working Channel adds messages to voice signal that provides for
extracting units from calls
– Control Channel continues to send update messages to provide late
entry for other units
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Call Processing (cont.)
Calling unit releases PTT and sends Channel Release message
Working Channel sends Channel Drop message out to all units
All units return to Control Channel
Channel Access
– If Channel Request is valid, Control channel will assign the call to a
Working Channel
– If Group or Individual ID is not properly programmed into system,
Call is denied
– Network Switching Server (VNIC) will route the call to other systems
as necessary
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Call Processing Exceptions
Call Queued
– All channels are assigned to other calls
– Automatically placed in queue for next available Working Channel
– Queuing priority determines order of channel assignment
Call Denied
– System programming does not allow request
?
– Out of range of Control Channel
?
– Retry in different location
?
System Busy
?
– System programming can not complete call at present time
?
– Individual call to busy radio
– Retry later
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Emergency Call Processing
Emergency button on mobiles and portables initiates emergency call or
emergency alert
Elevates talkgroup to emergency status
Dispatcher notification through console
Other radios listening to talkgroup are notified with an audible alert
Group call
– Requests access for a high priority Emergency call
– Flags Consoles and other units in group with *RX EMER*
– Identifies caller
Clearing an Emergency
– Return group to normal status
– Radio must be programmed for Clear Emergency
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Group Call Scanning
Radio is able to monitor multiple groups
Radio can only receive one group at a time
Responding to a call (programmable)
– Selected group
– Scanned group (within timer period)
Scan groups on Scan List
– Fixed list in programming
– Programmable by user
Scan Control
– Fixed in programming
– Controlled by user
Priority 1 Group
Priority 2 Group
Group 1
?
Group 2
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How Far Does it Cover?
???
Many factors affect coverage:
Site Location
Urban clutter (+ & -)
Reflections / Multipath (+ & -)
Ducting over water (+)
Wet pine needles (-)
Weather (+ & -)
Frequency (+ & -)
Earth curvature
Many others… (+ & -)
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ProScan
Site 1
Site 2
Network
Switching
Center
Enhanced System Scanning Feature (compared to WASS):
– Algorithm Based on Received Signal Strength Indicator and CC
Verification
– Scans after Signal RSSI Drops below a User Defined Threshold
– Searches for new System Based on Defined Adjacent System Scan List
– Switches to new System, if User Defined Criteria is Met
– Provides Better Audio Quality
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Radio Programming
Every M/A-COM P25 radio is programmed with a personality.
A Data file:
– Directs the operating characteristics of the radio
– Interfaces the radio to a system
This personality is what makes a radio unique to the user of the radio.
Programming Cables
TQ 3392 – P7100, P5100
TQ 3409 – M7100 (Shop)
TQ 3410 – M7100 (Field)
TQ 3419 – P7100, P5100
(without TQ 3370 interface)
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C3 MaestroIP Dispatch Consoles
Purpose:
Monitors & controls multiple Groups at a single physical position
A single Microphone/PTT and Selected & Unselected Speakers
Adds Patch & Simulselect capability to the P25 System
Provides EMERGENCY control
Physically:
Can be programmed with 112 Groups
Simultaneous audio based on Talk path licenses
– Standard – 4 talk paths
– Maximum – 20 talk paths
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Terminology
AES
CAI
CNM
CTCSS
DES
DVU
FDMA
GWB
IMBE
IP
Advanced Encryption Standard (256 bit encryption)
Common Air Interface
Centralized Network Manager
Continuous tone coded squelch system
Digital Encryption Standard (56 bit encryption) – Type III or
DES-OFB
Digital Voice Unit
Frequency Division Multiple Access
Gateway Board; OpenSky term for the Interoperability
Gateway DVU board
Improved Multiband Excitation – 3rd generation voice
encoder developed by Digital Voice Systems, Inc.
Internet protocol
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Terminology
KMF
LMR
MDIS
MES
MME
NAS
NMC
NOC
NSC
NSS
P25
Key Management Facility
Land Mobile Radio
Mobile Data Intermediate System; software on the NSS
Mobile End System. Mobile or portable.
Miniature Mobility Exchange
Network Administration System
Network Management Console. Previous name for RNM
Network Operations Center
Network Switching Center
Network Switching Server
APCO Project 25; a standard Common Air Interface protocol
for radio operation and system interface specifications
developed by TIA to provide for interoperability of different
manufacturer’s equipment
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Terminology
PSTN
PTT
RF
RNM
RX
SitePro
SMI
TDMA
TX
UAS
VES
VNIC
VoIP
Public Switched (or Service) Telephone Network
Push-To-Talk (depressing the radio transmit key)
Radio Frequency
Regional Network Manager
Receive or Receiver
SitePro Controller (controller for each repeater station)
Site Management Interface; software installed on the
Network Sentry
Time Division Multiple Access
Transmit or Transmitter
Unified Administration System
Voice End System. User.
Voice Network Interface Controller, software on the NSS
Voice over IP
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