Inside Dmr Radio With Ambe 2 Vocoder: Technical Details, Standards, and Applications for Professionals

Types of DMR Radios with AMBE+2 Vocoder

Digital Mobile Radio (DMR) technology has revolutionized two-way communication by offering clearer audio, improved spectrum efficiency, and advanced features. A key component in high-quality DMR radios is the AMBE+2 (Advanced Multi-Band Excitation) vocoder, which provides superior voice compression and clarity even in noisy environments. This guide explores the two primary categories of DMR radios equipped with AMBE+2 technology, detailing their design, capabilities, and ideal applications.

Handheld Portable Radios

Compact, lightweight, and battery-powered, handheld DMR radios are designed for portability and ease of use. These devices fit comfortably in the palm of your hand, making them ideal for mobile communication in dynamic environments.

Key Features

• Lightweight and ergonomic design
• Battery-operated with long life (typically 8–24 hours)
• Integrated antenna and display
• Water and dust resistant (IP54–IP67 ratings common)
• Support for GPS, Bluetooth, and text messaging

Limited By

• Lower transmit power (typically 1–6 watts)
• Shorter range without repeater support
• Smaller battery capacity requires frequent charging
• Fewer expansion options compared to base stations

Best for: Outdoor recreation, hiking, event coordination, security patrols, amateur radio (ham) operators, and emergency response teams needing mobility.

Mobile & Base Station Radios

Designed for installation in vehicles or fixed locations, mobile and base station DMR radios deliver higher power output and enhanced functionality. These units are not portable but offer superior performance for continuous and long-range communication.

Key Features

• Higher transmit power (typically 25–50 watts)
• Connected to external antennas for extended range
• Powered by vehicle electrical systems or AC mains
• Advanced digital signal processing (DSP) for noise reduction
• Support for multiple channels, repeaters, and trunking systems
• Compatibility with external microphones, speakers, and data devices

Limited By

• Not portable—requires installation
• Larger size and weight
• Higher cost and complexity
• Dependent on stable power sources

Best for: Emergency services, public safety, transportation fleets, industrial operations, dispatch centers, and any application requiring reliable, long-distance digital communication.

Radio Type	Power Output	Portability	Range	Typical Use Cases
Handheld Portable	1–6 W	High (battery-powered)	1–5 miles (varies with terrain/repeaters)	Hiking, security, events, amateur radio
Mobile/Base Station	25–50 W	Low (fixed installation)	10+ miles (with external antenna)	Public safety, fleet operations, dispatch

Expert Tip: When using DMR radios with AMBE+2 vocoders, ensure all radios in your network support the same codec for optimal voice clarity. Incompatible vocoders can result in distorted or robotic audio, even if the DMR protocol is otherwise compatible.

Why AMBE+2 Matters

The AMBE+2 vocoder is a critical component in modern DMR systems, enabling efficient voice encoding at 3,600 bps while maintaining high intelligibility. It excels in noisy environments—such as construction sites, emergency scenes, or moving vehicles—by filtering background noise and preserving vocal clarity. Radios equipped with AMBE+2 deliver natural-sounding audio, reduced bandwidth usage, and improved battery life, making them the preferred choice for professional and enthusiast users alike.

Functions and Features of DMR Radios with AMBE+2 Vocoder Technology

Digital Mobile Radio (DMR) systems equipped with AMBE+2 vocoder technology represent a significant advancement in two-way radio communication. These radios deliver superior voice clarity, enhanced security, and greater operational efficiency across various industries—including public safety, construction, transportation, and event management. While specific capabilities may vary by model and manufacturer, the following outlines the core functions and features commonly found in modern DMR radios.

Core Operational Bands: VHF and UHF Compatibility

VHF Band (136–174 MHz)

Operating in the Very High Frequency (VHF) range, these DMR radios are ideal for outdoor and rural environments where longer wavelength signals can travel farther and penetrate foliage more effectively. VHF is particularly well-suited for open terrain, maritime use, and large agricultural or utility operations.

UHF Band (403–470 MHz)

Ultra High Frequency (UHF) models excel in urban and indoor settings due to their shorter wavelengths, which better penetrate buildings and concrete structures. UHF is preferred for dense city environments, warehouses, shopping centers, and multi-floor facilities where signal obstruction is common.

Note: Many DMR radios are dual-band capable, allowing seamless switching between VHF and UHF frequencies for maximum versatility across different work environments.

Digital Voice Transmission with Enhanced Clarity

Unlike analog FM transmission, DMR uses digital modulation to encode voice data, enabling clearer, more reliable communication over long distances. By utilizing time-division multiple access (TDMA), DMR splits a single 12.5 kHz channel into two time slots, effectively doubling channel capacity without increasing bandwidth usage.

Digital encoding reduces background noise, minimizes interference, and maintains consistent audio quality even at the edge of coverage areas. This results in crisp, intelligible voice transmission—critical in high-noise environments such as construction sites or industrial plants.

Emergency Alert System: Rapid Response in Critical Situations

DMR radios are equipped with a dedicated emergency alarm feature designed to signal distress instantly. When activated—typically via a dedicated button—the radio transmits a loud, attention-grabbing alert tone along with a data flag to dispatch consoles or monitoring systems.

This feature is engineered to function reliably even in extreme conditions, including heavy fog, smoke, or loud industrial environments. In networked systems, emergency alerts can trigger location tracking, automatic logging, and priority communication routing, significantly improving responder safety and coordination.

AMBE+2 Vocoder: Superior Voice Encoding and Noise Reduction

The Advanced Multi-Band Excitation Plus 2 (AMBE+2) vocoder is a key component of DMR audio performance. It converts analog voice signals into highly compressed digital data using sophisticated algorithms that preserve vocal nuances while minimizing bandwidth consumption.

Key advantages include:

• High-definition voice quality even in noisy or low-signal conditions
• Efficient compression at 3,600 bps, enabling clear communication within narrowband channels
• Robust performance in weak signal areas, reducing dropouts and garbled audio
• Low latency for natural, real-time conversation flow

Privacy and Data Security Through Encryption

DMR radios support multiple layers of security to protect sensitive communications:

Basic Privacy (Scrambling)

Simple voice inversion or scrambling techniques prevent casual eavesdropping on open channels.

Advanced Encryption (AES/DES)

Professional-grade models offer 128-bit or 256-bit AES encryption, ensuring that only authorized users with matching keys can decode transmissions. This is essential for law enforcement, security teams, and corporate operations requiring confidentiality.

These security protocols safeguard not only voice but also text messages, GPS data, and system commands transmitted over the network.

Multiple Talk Groups: Efficient Communication Management

DMR supports the creation of multiple virtual talk groups, functioning like digital "channels" that allow users to organize communication by department, function, or project. For example:

• Operations Team – Coordinates field activities
• Maintenance Crew – Handles equipment issues
• Security Staff – Monitors site safety

Users can switch between groups instantly or monitor multiple groups simultaneously depending on radio capabilities. This enhances coordination, reduces channel congestion, and improves operational efficiency—especially in large organizations.

Waterproof and Rugged Design for Harsh Environments

Designed for durability, most DMR radios feature robust, sealed enclosures built to withstand dust, moisture, and physical impacts. They typically carry an IP (Ingress Protection) rating from IP54 to IP67:

IP Rating	Protection Level	Typical Use Case
IP54	Dust-protected, splash-resistant	General outdoor use, light rain
IP65	Dust-tight, low-pressure water jets	Construction, industrial sites
IP67	Dust-tight, submersible up to 1m for 30 minutes	Maritime, emergency services, extreme weather

These rugged designs ensure reliable operation in rain, snow, mud, and high-humidity environments, making DMR radios suitable for 24/7 mission-critical applications.

Important: Always verify the specific features and certifications of your DMR radio model. Not all radios support encryption, dual-band operation, or full IP67 ratings. Consult the manufacturer’s specifications and ensure compliance with local regulatory standards (e.g., FCC, ETSI) before deployment.

Applications of DMR Radio with AMBE +2 Vocoder

Digital Mobile Radio (DMR) systems equipped with the AMBE +2™ (Advanced Multi-Band Excitation) vocoder represent a significant advancement in voice communication technology. By combining efficient digital voice encoding with robust two-way radio performance, these systems deliver clear, secure, and reliable communication across a wide range of industries. The AMBE +2 vocoder enhances audio clarity, reduces background noise, and enables high-quality voice transmission even in low-bandwidth environments—making it ideal for mission-critical operations where communication integrity is paramount.

Public Safety Agencies

Police, fire departments, emergency medical services (EMS), and other first responders rely on DMR radios with AMBE +2 vocoders for seamless coordination during high-pressure situations. The enhanced audio quality ensures commands are clearly understood, even in loud or chaotic environments such as disaster zones or traffic accidents.

• Crystal-clear voice transmission improves situational awareness and decision-making
• Secure, encrypted channels protect sensitive operational information
• Long battery life supports extended shifts without interruption
• Integration with dispatch systems enables real-time team tracking

Key benefit: Improved intelligibility in noisy environments enhances officer safety and response effectiveness

Industrial & Manufacturing Sites

Large-scale industrial facilities—including oil refineries, chemical plants, and manufacturing centers—use DMR radios to maintain constant communication between control rooms, field technicians, and maintenance crews. Remote workers in isolated or hazardous areas can instantly contact supervisors for guidance or emergency assistance.

• Explosion-proof and intrinsically safe models available for hazardous environments
• Group calling features streamline coordination across departments
• Text messaging capability allows silent communication in noisy zones
• GPS-enabled units support worker location monitoring for safety compliance

Operational impact: Reduces downtime and improves incident response times through instant team connectivity

Construction Sites

On dynamic construction sites, DMR radios enable continuous communication between site managers, crane operators, equipment operators, and ground crews. This real-time connectivity is essential for coordinating lifts, managing material delivery, and reporting safety hazards.

• Durable, weather-resistant designs withstand harsh job site conditions
• Emergency alert buttons allow workers to signal distress instantly
• Clear audio helps prevent miscommunication that could lead to accidents
• Repeater systems extend coverage across multi-story or sprawling developments

Safety advantage: Enables rapid emergency response, contributing to OSHA compliance and reduced workplace incidents

Transportation & Logistics

Fleet operators, trucking companies, rail services, and maritime crews use DMR radios to coordinate vehicle movements, monitor driver status, and manage delivery schedules. In maritime applications, ship-to-ship and ship-to-shore communication is enhanced with digital clarity and extended range.

• Efficient spectrum use allows multiple fleets to operate in the same area
• Low-latency communication supports time-sensitive logistics decisions
• Integrated GPS tracking improves route optimization and asset visibility
• Interoperability with legacy analog systems ensures smooth transition

Business value: Increases fleet efficiency and customer satisfaction through better dispatch control

Hospitality Industry

Hotels, resorts, restaurants, and event venues use DMR radios to coordinate housekeeping, maintenance, front desk, and security staff. The quiet, discreet communication helps maintain a professional atmosphere while ensuring quick service delivery.

• Compact, lightweight handsets are easy to carry during long shifts
• Private calling features allow discreet communication between departments
• Enhanced audio quality ensures clarity in busy lobbies or kitchens
• Security teams can patrol large properties with uninterrupted coverage

Guest experience: Faster response times to guest requests improve service ratings and satisfaction

Security Agencies

Private security firms and law enforcement support units deploy DMR radios in patrol vehicles and on foot to maintain constant communication. The ability to create virtual talk groups allows different teams to collaborate seamlessly during large-scale operations.

• Encrypted channels prevent eavesdropping on patrol movements or strategies
• Man-down alarms and emergency alerts enhance officer safety
• Seamless roaming between sites ensures continuous coverage
• Interoperability with public safety networks enables joint operations

Tactical advantage: Real-time coordination improves incident response and surveillance effectiveness

Event Management

For large public events—such as concerts, marathons, festivals, and parades—event organizers depend on DMR radios to coordinate volunteers, medical teams, traffic controllers, and security personnel. With multiple teams operating simultaneously, clear and organized communication is critical.

• Customizable talk groups separate functions (e.g., medical, logistics, security)
• Text messaging reduces channel congestion during peak activity
• Ruggedized radios perform reliably in outdoor and variable weather conditions
• Fast deployment systems support temporary communication networks

Operational efficiency: Ensures all teams remain synchronized and can respond rapidly to evolving situations

Education Sector

Universities, school districts, and large educational campuses use DMR radios to connect campus police, security officers, facility managers, and administrative staff. During emergencies—such as severe weather, medical incidents, or security threats—rapid communication is essential.

• Instant group alerts notify all personnel of emergencies simultaneously
• Digital clarity ensures instructions are understood during high-stress events
• Integration with PA systems and emergency notification platforms
• Long-range coverage spans entire campuses, including remote buildings

Campus safety: Enables swift lockdown procedures and emergency evacuations when needed

Pro Insight: When deploying DMR systems with AMBE +2 vocoders, consider investing in infrastructure such as repeaters and base stations to maximize coverage. Additionally, training users on proper radio etiquette and emergency protocols ensures optimal utilization of the system’s capabilities. For organizations transitioning from analog, hybrid DMR systems offer a cost-effective path to digital transformation without sacrificing existing investments.

Sector	Primary Use Case	Key Feature Utilized	Communication Benefit
Public Safety	Emergency Response Coordination	Encryption & Emergency Alerts	Secure, reliable command communication
Industrial	Remote Worker Connectivity	Intrinsically Safe Radios	Continuous operations in hazardous zones
Construction	Hazard Reporting & Equipment Coordination	Durability & Audio Clarity	Reduced accident risk and faster response
Transportation	Fleet Tracking & Dispatch	GPS & Spectrum Efficiency	Improved logistics and fuel efficiency
Hospitality	Staff Coordination & Guest Service	Compact Design & Private Calls	Discreet, efficient service delivery
Security	Patrol Coordination & Incident Response	Man-Down Alarms & Roaming	Enhanced officer safety and coverage
Event Management	Multi-Team Synchronization	Talk Groups & Text Messaging	Real-time coordination under pressure
Education	Emergency Notification & Campus Safety	Group Alerts & Wide Coverage	Immediate response to critical incidents

Additional Advantages of AMBE +2 Vocoder Technology

• Superior Voice Quality: Delivers natural-sounding audio with minimal delay, even in weak signal areas
• Noise Suppression: Filters out background sounds like engine noise or wind, improving speech intelligibility
• Spectrum Efficiency: Supports two voice channels in a single 12.5 kHz bandwidth, doubling capacity
• Interoperability: Compatible with other digital standards through gateway solutions
• Future-Proofing: Supports firmware updates and integration with IP-based communication systems

How to Choose AMBE 2 Vocal DMR Radios: A Complete Buyer’s Guide

Selecting the right DMR (Digital Mobile Radio) with AMBE 2+ vocoder technology is essential for achieving high-quality voice communication in professional, industrial, public safety, and amateur radio environments. Unlike analog systems, DMR radios use digital signal processing to compress and transmit voice efficiently. The AMBE 2+ (Advanced Multi-Band Excitation) vocoder plays a crucial role in ensuring clear, intelligible audio even under weak signal conditions.

This comprehensive guide outlines the key factors to consider when purchasing a DMR radio equipped with AMBE 2+ vocoder technology, helping you make an informed decision based on your operational needs, regulatory compliance, and performance expectations.

Important Note: AMBE 2+ is a proprietary vocoder developed by Digital Voice Systems, Inc. (DVSI). All DMR radios must be licensed to use AMBE technology. Ensure the manufacturer has valid licensing to avoid potential legal or interoperability issues.

Key Factors to Consider When Choosing AMBE 2+ DMR Radios

1. Frequency Band and Power Output

   DMR radios are available in two primary form factors: handheld (portable) and mobile (vehicle-mounted), each with distinct capabilities:

   • Handheld DMR Radios: Compact and battery-powered, ideal for field personnel. Most operate in VHF (136–174 MHz) or UHF (400–470 MHz) bands. Typical power output ranges from 1 to 5 watts, suitable for short- to medium-range communication.
   • Mobile DMR Radios: Installed in vehicles or fixed stations, these units connect to external antennas and power sources. They offer higher transmit power (up to 50 watts), extended range, and support for multi-band operation in some models.

   Buyer Tip: Choose frequency bands that match your operating environment—UHF for urban or indoor use, VHF for open rural areas. Verify that the radio supports your region’s allocated DMR frequencies.

2. Licensing and Regulatory Compliance

   Operating DMR radios legally requires adherence to national telecommunications regulations:

   • In the United States, the Federal Communications Commission (FCC) regulates DMR usage. While some DMR radios can operate under Part 90 (business/industrial) or Part 95 (GMRS), commercial and business communications typically require an individual or common carrier license.
   • In the European Union, DMR Tier I and Tier II devices may operate under license-exempt status in specific bands (e.g., PMR446), but higher-power Tier II and Tier III systems require licensing.
   • Other countries have their own regulatory bodies (e.g., ISED in Canada, ACMA in Australia).

   Action Step: Confirm that the DMR radio model is certified for use in your country and that you have the appropriate license for your intended application. Unauthorized use can result in fines or equipment seizure.

3. Vocoder Performance and Voice Quality

   The AMBE 2+ vocoder is a cornerstone of DMR audio quality. It compresses voice into a 3,600 bps digital stream while preserving clarity and natural tone:

   • Delivers crisp, noise-resistant audio even in low-signal or high-interference environments.
   • Superior to older vocoders (like AMBE+) in terms of reduced robotic artifacts and improved speech intelligibility.
   • Enables efficient spectrum use by allowing two voice channels (Time Slot 1 and 2) within a single 12.5 kHz channel.

   Pro Tip: Listen to audio samples or conduct field tests if possible. Some radios implement AMBE 2+ more effectively due to better microphone processing and noise cancellation algorithms.

4. Channel Capacity and Duplex Operation

   DMR uses TDMA (Time Division Multiple Access) to split a single frequency into two time slots, enabling two simultaneous conversations on one channel:

   • Simplex Mode: Communication on a single channel using one time slot (common in handhelds).
   • Duplex Mode: Full-duplex communication via a repeater, allowing both time slots to be used independently.
   • Channel Capacity: Refers to the number of channels and time slots the radio can store and access. Higher-end models support hundreds of channels with programmable time slots.

   Recommendation: For teams requiring multiple communication groups (e.g., security, logistics, medical), choose a radio with at least 16 programmable channels and dual-time-slot support. Ensure compatibility with your repeater infrastructure.

5. Emergency and Notification Features

   Safety-critical environments demand reliable emergency signaling capabilities:

   • Emergency Button: Triggers an immediate alert to dispatch or monitoring stations, often accompanied by GPS location data. Common in law enforcement, EMS, and security radios.
   • Man-Down / Kill Switch: Automatically sends an alarm if the radio remains motionless beyond a set period (man-down) or when manually activated (kill switch). Used in industrial and hazardous environments.
   • Remote Monitor & Stun/Kill: Allows supervisors to remotely activate a radio’s microphone or disable it entirely for security purposes.

   Application Guidance: Prioritize models with programmable emergency buttons and GPS integration if used in public safety, healthcare, or remote field operations.

6. Surge Protection and Power Supply Stability

   Mobile DMR radios are particularly vulnerable to voltage spikes from vehicle electrical systems:

   • Look for models with built-in transient voltage suppression (TVS) or surge protection circuits.
   • Ensure the radio operates within a wide input voltage range (e.g., 10–16 VDC) to handle alternator surges and battery fluctuations.
   • Use an external in-line fuse and surge protector for added safety, especially in older vehicles or harsh electrical environments.

   Preventive Measure: Always connect mobile radios directly to the battery with proper fusing—avoid cigarette lighter adapters for permanent installations.

Feature	Handheld DMR Radios	Mobile DMR Radios	Why It Matters
Power Output	1–5 W	25–50 W	Higher power = greater range and penetration
AMBE 2+ Support	Standard in Tier II/III models	Universal in professional models	Ensures clear, digital voice quality
Channel Capacity	16–128 channels	100–1000+ channels	Supports complex communication networks
Emergency Features	Basic emergency button	GPS, man-down, remote stun	Critical for safety and accountability
Power Protection	Battery management	Surge protection, wide voltage input	Prevents damage from electrical spikes

Expert Tip: Always purchase DMR radios from authorized dealers and verify firmware authenticity. Counterfeit or unlicensed firmware may disable AMBE 2+ functionality or violate regulatory standards. Regular firmware updates can improve vocoder performance and add new features.

Additional Recommendations

• Ensure compatibility with your existing DMR network or repeater system (Brands: Motorola, Hytera, Kenwood, AnyTone, etc.).
• Consider IP rating (e.g., IP67) for dust and water resistance in outdoor or industrial use.
• Look for Bluetooth, GPS, and SMS/text messaging capabilities for enhanced functionality.
• Test interoperability with other team radios before large-scale deployment.
• Train users on proper DMR etiquette, including time slot management and emergency protocols.

Choosing the right AMBE 2+ DMR radio involves balancing technical performance, regulatory compliance, and operational needs. By carefully evaluating frequency, power, vocoder quality, safety features, and durability, you can select a system that delivers reliable, crystal-clear communication in any environment. When in doubt, consult with a certified radio technician or system integrator to ensure optimal setup and long-term performance.

DMR Radio with AMBE 2 Vocoder: Frequently Asked Questions

Q1: What is the difference between an AMBE and an AMBE 2 Plus vocoder?

The AMBE (Advanced Multi-Band Excitation) vocoder is a digital voice compression technology developed by Digital Voice Systems, Inc. (DVSI), widely used in digital radio systems for its ability to deliver clear audio over narrow bandwidths. It efficiently encodes human speech into a compact digital format, making it ideal for low-bandwidth applications such as DMR (Digital Mobile Radio), satellite communications, and amateur radio.

AMBE+2 is an enhanced version of the original AMBE codec, offering significant improvements in voice clarity, naturalness, and intelligibility—especially under poor signal conditions. Key advantages include:

• Higher Bitrate Efficiency: Optimized encoding allows for better voice reproduction at the same data rate.
• Improved Noise Handling: Performs better in noisy environments or weak signal areas, reducing robotic or garbled audio artifacts.
• Lower Latency: Faster processing ensures more natural conversation flow.
• Better Support for Accents and Speech Variations: More robust recognition and reproduction of diverse vocal patterns.

In DMR radios, AMBE+2 is the standard vocoder used to encode voice signals into 3,600 bps digital streams, providing superior audio quality compared to earlier codecs. This makes it a preferred choice for professional, public safety, and amateur radio users who demand reliable and clear communication.

Q2: Can I use a DMR radio without a subscription?

Yes, you can absolutely use a DMR radio without paying any subscription fees. DMR is an open digital radio standard developed by the European Telecommunications Standards Institute (ETSI), meaning there are no licensing costs to operate the equipment or use the protocol itself.

However, it's important to distinguish between:

• DMR Equipment Use: No subscription is required to transmit or receive on DMR radios, provided you have the appropriate amateur radio license (if operating on ham bands) or business license (for commercial use).
• Network Access: Some DMR networks—like BrandMeister, DMR-MARC, or commercial trunked systems—offer enhanced features such as global talkgroups, call routing, and logging services. While many of these networks are free to use (especially in the amateur radio community), others may require registration or paid subscriptions for full access.
• Repeater Access: Many local DMR repeaters are freely accessible, but some may require you to register your radio’s unique ID (Radio ID) with a network to enable communication.

For hobbyists, emergency preparedness groups, or small businesses, DMR offers a cost-effective, scalable solution without mandatory recurring fees. Always ensure your radio is programmed correctly and complies with local regulations regarding frequency use and identification.

Q3: How many channels are in a DMR radio?

The term "channels" in DMR refers not only to traditional radio frequencies but also to time slots, which significantly increase communication capacity. Unlike analog FM radios that support one conversation per frequency, DMR uses TDMA (Time Division Multiple Access) technology to split each frequency into two time slots, effectively doubling the number of simultaneous conversations.

Here’s a breakdown of DMR channel capacity:

Feature	Description
Time Slots per Channel	Each DMR frequency (channel) supports two time slots: Time Slot 1 (TS1) and Time Slot 2 (TS2), allowing two separate conversations on the same frequency at the same time.
Channel Capacity	A single DMR repeater can handle two concurrent calls. For example, one user can communicate on TS1 while another uses TS2, both on the same frequency.
Number of Channels	The total number of programmable channels depends on the radio model. Entry-level handhelds may support 128–256 channels, while advanced models can store 1,000+ channels with multiple zones and scan lists.
DMR Tiers	Tier I: License-free (in some regions), low power, direct mode only. Tier II: Licensed conventional trunked systems, used by businesses and public safety. Tier III: Trunked infrastructure for large-scale networks with advanced call handling.

Additionally, DMR supports both direct (radio-to-radio) and repeater-based communication. When using repeaters, each site typically operates on one frequency pair (one for transmit, one for receive), but still utilizes two time slots for increased efficiency.

In summary, while a DMR radio may have hundreds of stored channels, the key innovation lies in its ability to support two simultaneous communications per frequency through time slot technology—making it far more spectrally efficient than analog systems.