The engineering world has been working on the development and evaluation of IBOC transmission for some time. The NRSC began evaluation proceedings of general DAB systems in 1995. After the proponents merged into one, Ibiquity was left in the running for potential adoption. In the fall of 2001,the NRSC issued a report on Ibiquity's FM IBOC. This comprehensive report runs 62 pages of engineering material plus 13 appendices. All of the system with its blend-to analog operation as signals levels changes. The application of the FM IBOC has been studied by the NRSC and appears to be understood and accepted by radio engineers. AM IBOC has recently been studied by an NRSC working group as prelude to its adoption for general broadcast use .Its was presented during the NAB convention in April. The FM report covers eight areas of vital performance concerns to the broadcaster and listener alike .If all of these concerns can be met as successfully by AM IBOC, and the receiver manufactures rally to develop and produce the necessary receiving equipment. The evaluated FM concerns were audio quality, service area, acquisition performance, durability, auxiliary data capacity, and behavior as signal degrades stereo separation and flexibility. The FM report paid strong attention to the use of SCA services on FM IBOC. About half of all the operating FM stations employ one or more SCAs for reading for the blind or similar services. Before going to the description of FM IBOC system, it is important to discuss the basic principles of digital radio, and IBOCtechnology.

1. 6/13/2014
1
ครк™©2012
Hai….!
Welcome

2. In Band On Channel Technology
For Digital Radio
Ashik S R
ashikask@live.com
6/13/2014
2
ครк™©2012

3. INTRODUCTION
In Band On Channel (IBOC) is a hybrid method of transmitting
digital , analog radio signals broadcast simultaneously on the same
frequency.
By utilizing additional digital subcarriers or sidebands, digital information
is “multiplexed” on an AM or FM analog, thus avoiding re-allocation of the
broadcast bands. However, by putting RF energy outside of the normally-
defined channel, interference to adjacent channel stations is increased
when using digital sidebands.
IBOC does allow for multiple program channels, though this can
entail taking some existing subcarriers off the air to make additional
bandwidth available in the modulation baseband. On FM, this could
eventually mean removing stereo. On AM, IBOC is incompatible with
analog stereo, and any additional channels are limited to highly-
compressed voice, such as traffic and weather. Eventually, stations can go
from mode(both analog and digital) to all digital, by eliminating the
baseband monophonic audio.
Digital Radio
6/13/2014ครк™©2012 3
In Band On Channel
Technology
For Digital Radio

4. A small screen
attached to the
digital receivers
displays text and
pictures. Text, data
and images
can be diffused at
the scale of a
country or a region.
Visteon's MACH DSP combined with iBiquity
technology brings HD Radio to reality
6/13/2014 7ครк™©2012

5. 6/13/2014 ครк™©2012 8
IBOC: a new system
In Band On Channel
Compatible with the current analogue radio formats.
Utilises the existing AM and FM bands by attaching a digital side-band signal to
the standard analogue signal.
For digital compression, the IBOC uses a perceptual audio coder (PAC).

6. 6/13/2014 ครк™©2012 10
IBOC technologies from
USADR and iBiquity Digital
The IBOC technology allows digital audio
broadcasting without the need for new
spectrum allocations for the digital signal.
It provides for enhanced sound fidelity,
improved reception and new wireless data
services. This enhancement to AM and
FM will offer tremendous growth opportunities
for broadcasters, manufacturers,
retailers and automotive manufacturers.

7. 6/13/2014 ครк™©2012 16
Basics of IBOC
• The IBOC technology is used to transmit CD-quality audio signals to
radio receivers along with such data as station, song and artist
identification, stock and news information and local traffic and
weather updates.
• The broadcasters can use the existing radio spectrum to transmit AM
and FM analogue simultaneously with higher quality digital signals.
• The system employs multiple digital signaling techniques, such as
redundant sidebands, blend, first adjacent cancellation and code and
power combining.
• To compress the audio data and increase transmission without losing
sound quality, it uses the PAC audio-compression technology.

8. 6/13/2014 ครк™©2012 17
An integral part of iBiquity Digital’s AM and FM digital broadcast technology,
the PAC audio-compression technology utilizes advanced signal processing and psycho-
acoustic modeling to interpret human hearing and eliminate redundancies and
irrelevancies in the audio signal.
iBiquity Digital has designed the PAC technology for Internet broadcasting as
well. Companies will use the PAC technology to encode and decode music, talk and
information programming that will be delivered over the Internet.
iBiquity Digital’s PAC technology will also be used in satellite digital radio.
Audio quality at a given compression rate is a crucial factor for satellite digital radio. With
PAC technology, a high audio quality can be obtained at various bitrates.

9. FM hybrid IBOC waveform
 Low-level digital sidebands are
added to each side of the analogue
signal.
 The bandwidth is limited to 200
kHz from the centre frequency.
 Restricting the digital sub-
carriers to 70kHz.
 This minimises interference
to the analogue host and adjacent
channels without exceeding the
existing spectral mask.
 This bandwidth is wide enough
to support a robust, hybrid IBOC
service with virtual CD-quality
audio that mirrors the coverage of
existing analogue radio stations.
6/13/2014 ครк™©2012 18
Fig. 1: FM hybrid IBOC power spectral density

10. 6/13/2014 ครк™©2012 20
Advanced FEC
Allows the combination of both
side bands.
Provide additional signal power
gain and coding gain.
Base line hybrid system
Simultaneously transmits 96
kbps of error – protected signals.
Digital audio information and
auxiliary services.
Dual side band structure
Enables the use of frequency
diversty.
Combat the effects of multipath
fading & interference.
IBOC technology employs redundant information placed
in the upper and lower sidebands to ensure that the system
performs in all radio environments. It further combats
interference through first adjacent canceller (FAC) technology.
FAC cancels the effects of a strong analogue adjacent channel
station that can easily wipe out a digital sideband. This patent-
pending technology greatly increases the chances of a sideband
survival and, when combined with redundant sideband
implementation, provides robust digital reception under all
interference conditions.

11. 6/13/2014 ครк™©2012 21
Since QPSK has a bandwidth efficiency of two bits
per second per hertz, it supports an information bitrate that
is sufficient for transmission of virtual CD-quality audio in
the bandwidth available. Orthogonal frequency-division
multiplexing (OFDM) allows frequency-division
multiplexing of many QPSK-modulated sub-carriers in an
orthogonal fashion such that each sub-carrier does not
interfere with its adjacent sub-carriers. This offers a high
level of robustness in a multipath channel. When combined
with FEC coding and interleaving, the digital signal’s
robustness is enhanced further.
The OFDM structure supports FEC coding techniques that
maximize performance in the non-uniform interference
environment. The most important coded bits can modulate OFDM
carriers that are located in the most protected regions of the
channel.

12. Multipath interference from multiple sources
6/13/2014 ครк™©2012 22

13. 6/13/2014 ครк™©2012 23
Block diagram of the IBOC DAB transmitter
Encodes the
audio
For blending
purpose
Ensure that the
compressed
data is robust
To produce
the DAB
base band
signal
Up convert
the base
band signal

14. 6/13/2014 ครк™©2012 24
Auxiliary
services
Ancillary
Services
Opportunistic
Data
120 kbps
Reducing Audio
quality & FEC parity.
Up to 32 kbps-
intermittently
multiplexed with
the audio.
Service Flexibility

15. 6/13/2014 ครк™©2012 25
Why delay in adoption?
The IBOC technology is not free from problems:
Low-power FM stations are prone to
Interference.
Receivers used for radio-reading services for
the blind may also be impacted.
IBOC licensing and service rules have not
been adopted yet.
iBiquity is the only IBOC vendor, stations
willing to use the IBOC technology will have no
choice but to make arrangements with iBiquity.

16. 6/13/2014 ครк™©2012 26
Let me Conclude
We have discussed about:
• Digital Radio
• Benefits of DAB
• RDS
• PAC used in IBOC
• USADR, iBiquity
•Service flexibility.
IBOC technology a hybrid method of transmitting digital
and analog radio signals simultaneously on same band. Through this
technology HD radio could make a reality. And let us hope that HD
radio become familiar soon to Indians too.

17. 6/13/2014 ครк™©2012 27
Credits
Slides prepared: Ashik.S.R
Seminar presented: Ashik.S.R
Guidance: Alex Shobana RajKumar
Special Thanks to
Sri. Justin Raj Thapas
The Principal ,CPTC
www.facebook.com/ashik.ask