What Is IBOC Radio

IBOC Handbook

Table of Contents

Section I - Background

Chapter 1

What is IBOC Radio?

Services Overview

Program Services


Tomorrow Radio

The HD Digital Radio Alliance

Program Service Data (PSD)

Station Information Service (SIS)

Advanced Data Services (ADS)

HD Radio Data Enhancements

The Digital Radio Environment

FCC First Report and Order


The Rise of IBOC

The NRSC and IBOC Development

NRSC Test and Evaluation Process

Digital Radio Transmission Technologies

Eureka-147 DAB




Integrated Services Digital Broadcasting for Terrestrial Sound Broadcasting (ISDB-TSB)

Satellite Digital Audio Radio Services (SDARS)

XM and Sirius Satellite Radio

SDARS Terrestrial Repeaters

Worldspace Satellite

Extended Digital Services

Digital Radio Express (DRE)

Stratos Audio Inc. and StratosInteractive

A Context For IBOC

Chapter 2

IBOC Precursors

IBOC’s Beginnings

New Technical Muscle

NRSC Cranks It Up

Testing Proponents’ Technologies: TGWG

Regulatory Progress

Evaluation Process: EWG

Standardization Testing: TPWG and EWG

Response to the Testing

Finally, Standards-Setting: ISDWG

FM Subcarrier Compatibility: DAB Subcommittee and Others

The Path to the HDC Codec: TPWG and EWG

AM Nighttime Performance and Compatibility: Outside-NRSC Review

Multicasting and the SIDTG

Surround Sound: The SSATG

Composite Surround Transport

Component Surround Transport

Surround Sound Case Studies

KUVO-FM, Colorado Public Radio

WZLX 100.7, CBS Boston

WGUC-FM 90.9, Cincinnati Public Radio

A Complete Standard in Two Steps: Data Put on Temporary Hold

After the Standard: DRB Subcommittee

Moving On

Section II – The Protocol Stack

Chapter 3

NRSC-5 Versions

Reference Documents

Informative References

The NRSC-5 Standard

Protocol Stack

Open Systems Model

NRSC-5 As Open System

One Standard, Several Modalities

“Services” Versus “Transports”

Structure of Section 2

Chapter 4

Audio Codec

Coded Audio Payload

Side Processes: The Configuration Administrator

Audio Transport

Program Service Data (“PSD”)


Opportunistic Data

Program Service Data

PSD Protocol and Transport

PSD ID3 Tags

PSD Etiquette

PSD Harmonization with RDS

PSD Transport

PSD Metadata

Audio Transport to Channel Multiplex

Chapter 5

Logical Channels

Logical Channels and the Frequency Domain

Logical Channels in the Time Domain

Logical Channel Types and Rates

Layer 2 PDU Structure

Folding in Data

L2 PDU Types

Layer 1—Processes Common to AM and FM


The Spectral Challenge of OFDM

How Scrambling Works

Convolutional Coding

Vectors and Matrices

FM IBOC Rate 2/5 Encoder Example


How Convolutional Encoding Helps

A Diagram Is Worth a Thousand Words



Layer 1 Continues

Chapter 6

Layer 1 Structure

System Control

IBOC in the Time Domain

Audio Sampling Rate Implications

Frame and Block Duration

Diversity Delay

AM Time Diversity

FM Time Diversity

The Symbol

Sync-ing Up

System Control Processing

Differential Encoding

Universal Time

Service Modes

AM Service Modes

FM Service Modes

Backward Compatibility

From Logical to Physical

Chapter 7


FM IBOC OFDM Frequency Plan

FM IBOC OFDM Modulation: Symbols


FM IBOC OFDM Modulation: Computational Basis


OFDM Sinusoidal Subcarriers

OFDM Symbol Pulses

Guard Interval

Cyclic Prefix

Pulse Shaping Function

Discrete Fourier Transform


Functions in Frequency and Time Domains

DFT Computation

Insert Pulse Shaping Function

A Stream of Symbols

Convolution Revisited

Chapter 8


AM Parameters


Amplitude Scaling

The Negated Complex Conjugate

Analog Channel

Complex Conjugate

Interference Protection

AM Pulse Shaping

Chapter 9

AM and FM Transmission System Specifications

Timing Issues

Signal Quality Issues

Error Vector Magnitude

Phase Noise


AM Amplitude and Phase Symmetry

Where to Measure AM and FM IBOC Specs

Spectral Emissions

Spectral Emissions Limits

Existing Analog Masks

IBOC Masks

Spectral Density

PSD and Spectrum Analyzer Settings

Spectrum Analyzer Detectors and Averaging

FM Mask

Digital-to-Digital Intermodulation

Analog/Digital Intermodulation

NRSC-5-A Mask (Hybrid FM IBOC)

Digital Sideband Self-Intermodulation

Hybrid Mask Fine Tuning

NRSC-5-A Mask (All-Digital FM IBOC)

OFDM Subcarrier Scaling

AM Mask

Analog-to Digital and Digital-to-Digital Intermodulation

NRSC-5-A Mask (Hybrid AM IBOC)

Analog Host Performance with Hybrid

NRSC-5-A Mask (All-Digital AM IBOC)

Discrete Components Exception

OFDM Subcarrier Scaling


IBAC Characteristics Differ From IBOC

The Radio "Channel"

Chapter 10

Station Information Service Protocol

Station Name (Short Format) a.k.a. Call Sign Standard

Call Sign Universal

Station Name (Long) a.k.a. Station Slogan Standard

Station Slogan Universal

Station ID Number

Station Location

Station Message

Time – ALFN and Time Parameters


Leap Seconds

SIS Parameter Messages

Leap Second Offsets

Local Time Data

Station Information Service Transport

Dedicated GPS Time Data

SIS PDU Housekeeping

SIS Scheduling Strategy

SIS Recap

Chapter 11

Advanced Applications Services Transport (AAT)

Data Transport Packet


AAT PDU Stream

Reed-Solomon FEC


Block Boundaries

Bearer Channels

Data Transport Packet Format

Port Number

Sequence Number

HDLC-Like Framing

Reed-Solomon Coding and Interleaving

Insertion into Bearer Channel

Opportunistic Bearer

Fixed Bearer

Above AAT— What Happens Outside NRSC-5?

Learning from History

A Better Reason to Use AAT Subchannels

The Radio Broadcasting Model for Advanced Data Services

Revenue Comparisons

Network Design Modeling

The Flow of IBOC Transmissions

The Concept of Multiple Services Sharing the Pipe

Use Cases and Service & Receiver Classifications

Applications Examples

Features Examples

Service Classes

Use Mapping

Receiver Classes

Classes Are the Key to Interoperability

Use Cases Lead to Protocols

Advanced Data Service Protocols (Not in NRSC-5)

Service Discovery


Traffic Message Channel

End of the IBOC Stack

Section III - Implementation

Chapter 12


Our AM Legacy

Backward Compatibility

What is Bandwidth, and What Does It Mean to Us?

Propelled from the Jet Age to the Space Age

Invisible IBOC

Antenna System Effects on the AM IBOC Signal

Outermost, or Primary, Sidebands

Outer or Secondary Sidebands

Inner or Tertiary Sidebands

Self-Canceling Sidebands

Transmitter Loading and System Bandwidth

Hermitian Symmetry


Analog’s Regulatory Vicious Cycle

Intermodulation Products

Pattern Bandwidth

High-Performance, Precision Antenna Systems

Nighttime AM Testing and Analysis


Chapter 13

Antennas and Combining

Analog FM Signals

Multi-station Combining

Combining Digital Signals in the FM Band

Common Amplification


Low-Level Combining

High-Level Combining

The High-Level Combiner

Why a 10-dB Combiner?

Efficiency and Heat Load

Mismatch and Isolation

Turn-around Loss

Minimizing Unwanted Interaction



Split-level Combining


Considering the Options


Combining with Antennas

The IBOC-to-Antenna Path

Dual-Feed Antenna

Separate-Antenna Operation

Separate-Antenna Research

Separate-Antenna Regulation

Multi-Station Antenna Systems

Common-Line IBOC to Multi-Station Combiners

Separate-Line IBOC and Multi-Station Combining

Crest Factor and Peak Power in Hybrid IBOC Transmission

OFDM Peak to Average

Relate OFDM to Analog

OFDM Peak to Analog Peak

OFDM RMS to Analog RMS

Hybrid Crest Factor

Difference Between Hybrid and Analog Crest Factors

Chapter 14


The Exciter

The Exgine

Connecting the Services to the Transmitter

Main Program Audio

Economizing for Multicasting

The Exporter

Breaking into the Protocol Stack

A New Transport Where None Had Been Necessary Before

Network Analysis

Quality of Service

Network Security

Another Approach

The Importer

Secure the Critical Network


Core Receiver Components

IBOC Coverage

FM Evaluation

Further FM Testing

Adjacent Channel Interference

AM Evaluation

Core & Enhanced


Effect of Adjacencies on AM IBOC Coverage

Conclusion of the IBOC Handbook

Appendix A:

IBOC Digital Radio Receiver Fundamentals

By DAVE WILSON, Consumer Electronics Association