- Analog radios do not have a vocoder, Which does analog-to-digital and digital- To-analog conversion (A/D and D/A).
- Vocoder - A special DSP device that converts the analog voice signal into a special digital code that uses less digital data than standard analog-to-digital converters.
- Modulation - a radio design that transmits digital data more efficiently within a specified bandwidth (25 or 12.5 khz).
- RF spectrum efficiency getting more channels from the same RF spectrum
- 25 khz channel split into two 12.5 khz channels in APCO
- Future migration to 6.25 khz (4:1 improvement) in APCO
- 25 khz channel split into four time slots (equivalent to four channels)
- Provides a 4:1 improvement
- Inherit privacy with digital transmission over analog
- Improved digital audio quality over analog
- Maintaining the same coverage for apco digital system providing greater consistency in voice quality
- No degradation in encrypted voice quality
- Provide integrated voice and data capability
- Spectrum efficiency - You are able to put more radio users onto one radio channel than ever before!
- analog radio channel supports one conversation
- Improved Voice Quality over same area - Voice transmissions are now clearer than ever before!
- Integrated Voice & Data
- You can now have both voice and data on one terminal today!
- Enhanced signaling features
- Embedded signaling offers enhanced communication features
- Voice Privacy
- Voice transmissions are transmitted digitally, so casual eavesdroppers cannot listen to conversations
- Improved Encrypted Voice Quality
- Digital voice transmissions can also be encrypted, thereby providing additional security, but with the same voice quality as unencrypted voice
- Only OPEN Standards available today:
- TETRA
- Terrestrial Trunked Radio
- Standard defined by ETSI, Europe
- APCO-25
- Association of Police Communication Officers Project 25
- Standard defined in US by TIA
- De-facto Industry Standards for Public Network
- iDEN (Motorola)
- Endorsed by ITU
- Several Proprietary Systems also available today:
- Tetrapol FDMA (Matra)
- OpenSky (MA/Coms)
- Association of Public Safety Communications Officials International
- APCO Project 25 Steering Committee
- National Association of State Telecommunications Directors
- U.S. Department of Defense
- National Communications System
- National Security Agency
- The Telecommunications Industry Association
- Communications manufacturers
- Users, associations, government agencies worldwide
- Public Safety focus
- Ensure competition through open architecture
- Allow effective inter/intra-agency communications
- Maximize spectrum efficiency
- Compatibility with existing equipment
- Gradual "migration-in-place" using existing spectrum
- Integrated voice and data services
- Project 25 defines several open interfaces for two-way radio communications systems
- The Common Air Interface is the Foundation for Digital Communication for both Conventional and Trunked Systems
- Most of the basic Functionality for Data Communications is already included in the CAI.
- APCO-25 has Selected the Data Encryption Standard, or DES, and the U.S.Federal government is providing the Development effort for OTAR or Over the Air Re-keying.
- Common Air Interface (CAI)
- The Major Goal of the APCO 25 System Standard is the Common Air Interface.
- Mobile and Portable equipment from any Manufacturer may be Freely Combined in any APCO 25 system.
- A Base Line of Radio Features will be Guaranteed from any System to Work through any Manufacturer's radio.
- Modulation . . . QPSK-C
- Channel Access. . . .FDMA
- Bandwidth. . . 12.5 kHz
- Channel Bit Rate . . . 9.6kbps
- Vocoder . . .IMBE
- Signaling Format. . . Protocol Adopted
- APCO-25 Signalling:
- 16,000,000 Unit ID's
- 64,000 Group ID's
- 4,000 Network ID's
- Source & Destination ID's
- Embedded Emergency
- Data Busy Bits
- Crypto Key & Algorithm ID's
- Manufacturer’s ID
- Reserve Bits For New Features
- ASTRO 25
- Fully Compliant with APCO P25
- ASTRO Conventional Systems
- Single Site
- Multiple Single Sites
- Receiver Voting
- Multicast Voting
- Simulcast
- Emergency Call
- Group Call
- Voice Selective Call
- PTT ID
- Console Patch
- Console Multi-Select
- APB Transmission
- Console Intercom
- Monitor
- Infrastructure:
- Quantar Base/Repeater
- Gateway
- Astrotac Comparator
- Packet Data Gateway
- Key Management Facility
- Mobiles:
- ASTRO SPECTRA Mobile
- ASTRO Spectra Plus
- XTL5000
- Portables:
- ASTRO Saber
- XTS 3000
- XTS 2500
- XTS 5000
- CLEAR
- Analog
- ASTRO 25 clear (digital)
- Encrypted
- Securenet DVP-XL
- ASTRO AES Coded
- Channel Mode Select
- Modulation Mode Select
- Auto ASTRO/Analog Receive
- Transmit Power Select
- Non-Priority Channel Scan
- Dual Priority Channel Scan
- Busy Indicator
- Channel Busy Transmit Inhibit
- Timeout Timer
- Emergency Channel Revert
- Talkaround
- Phase 1 : Upgrade Analog DVP-XL Securenet to ASTRO with DVP-XL
- Analog-only
- ASTRO-only
- Mixed mode
- Securenet Transparent
- Analog-only
- ASTRO-only
- Mixed mode
- Securenet Transparent
- Phase 1 – Upgrade Analog DVP-XL Securenet to ASTRO with DVP-XL
- Phase 1 – Link all sites to the HQ console
- Phase 1 – Upgrade with AVLS for GPS tracking
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