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P25 Trunked System Overview for Radio User Train-the-Trainer

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Presentation on theme: "P25 Trunked System Overview for Radio User Train-the-Trainer"— Presentation transcript:

1 P25 Trunked System Overview for Radio User Train-the-Trainer
Training Session Notes


3 Contents What is P25? M/A-COM P25 Terminal Equipment Call Types
Unit ID’s Call Processing Emergency Calls Group Scanning ProScan Terminology

4 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 Under TIA/EIA-102

5 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.

6 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

7 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 TRAINING TRNG 1

8 P25 Portable Radios P7170 (System Model) P7150 (Scan Model) P7130
(Select Model) P5150 (Scan Model) P5130 (Select Model) Objective: To demonstrate the operation of the major features of the P25 System Notes: In this section we are going to discuss - The Types of Calls - The Access Tones - The Emergency Call - What the Control Channel does - What the Working Channels do

9 M7100 Mobile Radio Hand-held Controller Scan Control Head
System Control Head

10 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 TRAINING TRNG 1

11 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

12 Unit Identification Unit ID Uniquely identifies radio to system
24 Bits – 16,777,216 Possibilities ( ,777,215) Only allow 1 – 9,999,999 Must be programmed into radio Allows Individual Calling Allows Call Tracking TRAINING TRNG 1

13 Conventional vs. Trunked
Computerized Assignment of Channels Service Employee Customer Conventional Trunked Service Counter

14 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

15 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

16 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 ? ? ? ? ?

17 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

18 ? 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

19 How Far Does it Cover? Many factors affect coverage: Site Location
??? Many factors affect coverage: Site Location Urban clutter (+ & -) Reflections / Multipath (+ & -) Ducting over water (+) Wet pine needles (-) Weather (+ & -) Frequency (+ & -) Earth curvature Many others… (+ & -)

20 ProScan Enhanced System Scanning Feature (compared to WASS):
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

21 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. TRAINING TRNG 1 Programming Cables TQ 3392 – P7100, P5100 TQ 3409 – M7100 (Shop) TQ 3410 – M7100 (Field) TQ 3419 – P7100, P5100 (without TQ 3370 interface)

22 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

23 Terminology AES Advanced Encryption Standard (256 bit encryption)
CAI Common Air Interface CNM Centralized Network Manager CTCSS Continuous tone coded squelch system DES Digital Encryption Standard (56 bit encryption) – Type III or DES-OFB DVU Digital Voice Unit FDMA Frequency Division Multiple Access GWB Gateway Board; OpenSky term for the Interoperability Gateway DVU board IMBE Improved Multiband Excitation – 3rd generation voice encoder developed by Digital Voice Systems, Inc. IP Internet protocol

24 Terminology KMF Key Management Facility LMR Land Mobile Radio
MDIS Mobile Data Intermediate System; software on the NSS MES Mobile End System. Mobile or portable. MME Miniature Mobility Exchange NAS Network Administration System NMC Network Management Console. Previous name for RNM NOC Network Operations Center NSC Network Switching Center NSS Network Switching Server P25 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

25 Terminology PSTN Public Switched (or Service) Telephone Network
PTT Push-To-Talk (depressing the radio transmit key) RF Radio Frequency RNM Regional Network Manager RX Receive or Receiver SitePro SitePro Controller (controller for each repeater station) SMI Site Management Interface; software installed on the Network Sentry TDMA Time Division Multiple Access TX Transmit or Transmitter UAS Unified Administration System VES Voice End System. User. VNIC Voice Network Interface Controller, software on the NSS VoIP Voice over IP

26 Technical Training Center M/A-COM, Inc.
Telephone Technical Training Center M/A-COM, Inc. Copyright© 2007 M/A-COM, Inc. All rights reserved.

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