Alan Jurison iHeartMedia Audience Poll Background of Digital Power Level FCC first authorized the use of the hybrid HD Radio IBOC system on in its First Report and Order 2002 MM Docket 99325 ID: 784185
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Slide1
Field Observations of Elevated FM HD IBOC Power Levels
Alan JurisoniHeartMedia
Slide2Audience Poll
Slide3Background of Digital Power Level
FCC first authorized the use of the hybrid HD Radio IBOC system on in its First Report and Order, 2002. (MM Docket 99-325)
Digital authority
was expanded in
the Second Order, 2007.
Many
of the
specifications and
operating conditions that are in use today were
codified
into official rules and
regulations.
Slide4Background of Digital Power Level
Initial power level selected for the digital carriers was one percent of the analog effective radiated power (ERP) level of the host station.
Expressed
in many different and interchangeable
conventions:
1% power
20
decibels below analog carrier
power
-20dBc (most
common notation used
today)
Testing
had been done with input from multiple parties to select a power level that provided what, at the time, seemed to be an effective digital coverage area, while at the same time balancing concerns about interference to adjacent FM
stations.
Unfortunately
, after many stations had adopted the FM hybrid system at the initial
-20dBc
operating power level, it became apparent that the digital coverage did not fully replicate the analog coverage, particularly in mobile edge-of-coverage and indoor environments.
Slide5Background of Digital Power Level
Many of the initial parties began researching and testing the use of elevated digital power levels in 2007.
In 2008 a formal request was submitted to the Commission to allow a blanket authorization to increase digital carrier power to 10% of the analog power,
or -10dBc.
The request for a power increase caused considerable debate within the industry, and created a robust conversation over the next two years.
Slide6Background of Digital Power Level
The end result was the Commission’s Third Order in 2010 which was a compromise between those requesting a blanket
-10dBc
authorization and those who wanted no potential additional interference with levels remaining
at -20dBc.
Blanket
authorization of increased digital power
to -14dBc
for most
stations.
A
procedure for some stations to increase from
-13.9dBc
to
-10dBc
with a special engineering
exhibit.
Special procedures
for grandfathered super-powered
stations.
Slide7Current State of Elevated Power
The rules have been in effect for over four years, and the amount of real world testing and experience with elevated powers continues to increase as stations invest in upgrading their transmission facilities to achieve higher digital powers
.
As of January 7, 2014, the Commission
reported:
50
FM station licensees had increased digital power between
-13.9dBc
and
-10dBc.
10
super-powered FM stations had requested
increases.
5
or fewer
have
applied for experimental authorizations of asymmetrical sideband
power.
The
Commission
has not
officially tracked nor tallied the number of digital notifications under the blanket authorization
between -19.9dBc and -14dBc.
Slide8Current State of Elevated Power
To gain some perspective on how many broadcasters have adopted elevated power levels, I explored the Commission’s CDBS database and located data
from the FCC Form 335 Digital Notification
applications.
Slide9Current State of Elevated Power
Digital
Carrier
Level
(
dBc
)
Station Count
(as of 2-5-2014)
Percentage of Implementation Level
All Entries
364
Not Applicable
Duplicates Removed
346
100%
>-19.9dBc30087% >-17.0dBc28081% >-14.9dBc24671% -14dBc19657% >-12dBc154%-10dBc103%
CDBS Records as of 2-5-2014
Note: Numbers do
not reflect stations that notified the Commission via letter before Form 335 was available, stations that applied for increased digital power via Special Temporary Authority (STA) or Experimental Authorizations.
Slide10Current State of Elevated Power
It is encouraging to see that since the Form 335 Digital Notification process has been in place:
87
%
employed elevated
carriers at some level.
57
%
employed -14dBc
power
level.
71
%
employed -14.9dBc
and higher
.
Slide11Current State of Elevated Power
With more than 365 stations running at some elevated power level, the Audio Division of the Commission has not received a single complaint of digital interference related to elevated digital power levels
meeting the digital interference resolution procedures
adopted in the Third Order.
The Commission
has
not
ordered
any FM station to reduce digital power or cease digital operation due to interference to an analog FM station.
Slide12Current State of Elevated Power
As the largest operator of commercial broadcast stations in the United States, iHeartMedia likely has the largest collection of elevated digital power stations in the country
.
I have had the opportunity
to
study a variety of stations employing HD Radio IBOC technologies operating at various power levels and configurations.
Slide13Elevated Power Studies
The coverage studies provided to the Commission in 2007-2008 time periods were based on the -10dBc digital power level.
Unfortunately
, it appears that few or no coverage studies were conducted at the blanket
-14dBc
power
level.
Over the last year and a half,
as part of my work supporting
iHeartMedia’s
data services, I
have driven thousands of miles in many different markets monitoring and logging the reception characteristics of elevated digital signals.
The stations I have had the opportunity to study in depth have operated in the range
between -14dBc to -20dBc
.
Slide14New York City – Empire State Building
Clear Channel Media + Entertainment operates five FM stations combined into the ERI “master” antenna atop the Empire State Building in New York.
Station
Freq
.
(
MHz)
Class
Analog
ERP
(kW)
HAAT
(
Meters)
Digital ERP
(Watts)
Digital
Level(dBc)WLTW106.7B6415239-14WWPR105.1B6415239-14WAXQ104.3B6415
60
-20
WHTZ
100.3
B
6
415
60
-20
WKTU
103.5
B
6
415
60
-20
Slide15New York City – Empire State Building
An extensive test drive in New York enabled me to collect data comparing digital power levels for these five signals during a single drive test. Measurement of these signals was performed concurrently, using multiple Audemat Navigator HD data logging receivers in a single vehicle.
This device records the analog and digital performance of a selected radio station and combines this data with GPS location data which is logged on a laptop computer.
The tests were conducted alongside a JVC KW NT800HDT aftermarket automotive HD Radio.
Data collected via the Navigators was compared in real-time during the drive route. The reception characteristics of the Audemat Navigator HD receivers and the JVC radio are very
similar.
Thus
, the data collected and the maps shown below are indicative of what a listener in an automotive environment may experience in a particular location.
Slide16Each Audemat Navigator HD receiver was furnished with its own calibrated ¼ λ (quarter wavelength) mast “mag mount” antenna and calibrated cables to record received analog signal strength values. In
an effort to keep those readings relevant, and to keep the digital signal pure as possible (i.e. not add splitters and amplification), each magnetic mount antenna was placed on the roof of the test vehicle and spaced apart. In addition, a Larsen NMOQ ¼ λ (quarter wavelength) mast “mag mount” antenna was also used for the JVC aftermarket automotive receiver.
Slide17New York City – Empire State Building
I recognize that the multiple antenna technique can create a potential for some directionality of reception, but having performed these tests over thousands of miles in many cities across the country in both travel directions, I have found that the directionality is not very impactful on the overall data collection and the listener experience
.
It is very indicative of “real world” testing, as most OEM automotive antenna designs have some form of directionality
.
In
my experience, some vehicle antennas have what I would consider an alarming amount of directionality, which could be an entire research topic and is outside the scope of this paper.
Slide18New York City – Empire State Building
With the vehicle equipped, data was collected on most major highways in the coverage area.The results were later converted into KML files and plotted in Google Earth
.
The values shown in
are
IBOC QI (Quality Indicator) values
.
The QI scale is from 0 (no signal) to 15 (good signal). Due to the “on/off” nature of digital reception, most of the values logged were 15 or 0. Good reception or a QI value of 15 is denoted by green circles. No reception or a QI value of 0 is denoted by red circles.
QI=9 areas appear as orange circles. These areas generally have a buffer starvation situation, where the radio is generally going in and out of FM analog and HD Digital reception (blending)
or
, when listening to an HD2 or HD3 Secondary Program Service (SPS) this is where you would typically hear dropouts or buffer starvation and digital artifacts.
Slide19New York City – Empire State Building
WLTW which is running -14dBc, the maximum blanket power level.WHTZ
which
is running -20dBc
, the original digital power
level.
One of the most challenging coverage areas in the New York Metro is in the hilly terrain in New Jersey. Of particular difficulty is the
I-287
corridor stretching from Mahwah through Morristown and south to Bridgewater. Also included in this area are parts of the
I-78
corridor.
This
area falls well within the predicted FCC F(50,50) 54dBu coverage contour of all five stations at the Empire State Building, but due to terrain it is a challenging environment for all stations in the market to cover.
Though
this area lies only 15-25 miles from the Empire State Building, analog FM reception can be noisy, with frequent multipath episodes and fading. Listeners to New York stations in these areas are accustomed to analog service with some noise.
Many
people commute from this area into Manhattan on a daily basis.
Slide20New York City – Empire State Building
WHTZ FCC F(50,50) 54dBu Service Contour
Area inside WHTZ 54dBu Service Contour
WLTW FCC F(50,50) 54dBu Service Contour
Area inside WLTW 54dBu Service Contour
WHTZ -20dBc
¼ Wave Antenna
WLTW -14dBc
¼ Wave Antenna
Slide21New York City – Empire State Building
Results were using ¼ λ (quarter wavelength) mast “mag mount” antennas. However, in my experience these antennas tend to be a “best case” scenario.
Many
factory installed OEM automotive antennas do not have this level of performance.
Historically
vehicles were equipped with external whip style antennas, these have largely become a thing of the past.
Automotive
designers are focused now more than ever on aesthetics of the vehicle and also aerodynamics for noise reduction and fuel economy.
This
has led to many concealed FM antenna designs, many of which tend not to perform as well as the traditional whip or mast antenna.
“Shark
fin” antennas. However, even those are starting to fade from automotive
designs.
Concealed
“in-glass” antennas which are generally located on the rear window or a side rear window. In my experience, these designs tend to provide poorer reception characteristics. I had noticed this as a general trend, but recently set out to measure this.
Slide22New York City – Empire State Building
In the analog realm it’s difficult and perhaps subjective to quantify the effects of antenna type on reception. Analog radios can use various techniques to mask the lack of adequate signal with
monoral
blending and diversity antenna reception.
With
digital these techniques do not work.
Diversity
antenna reception for HD is not currently available in any OEM design.
When
HD coverage data is collected, it is much easier to compare antenna performance from traditional antenna with some of these concealed antennas. Adapting the techniques used in
earlier,
I have done several tests involving mapping digital signals using automotive OEM antennas.
Slide23Instead of connecting the antenna to the factory installed radio, it was adapted into standard BNC connectors and then run through an FM
bandpass filter, variable attenuator, low noise RF amplifier, and an 8 port passive splitter. A spectrum analyzer was used to calibrate the system using the variable attenuator to ensure the amplifier was only making up for the losses of the bandpass filter and the 8 port passive splitter. Essentially the system was at unity gain, and each port of the 8 port splitter was within approximately 1dB of measured signal from the original output connector that was destined for the factory installed radio.
Slide24New York City – Empire State Building
WHTZ FCC F(50,50) 54dBu Service Contour
Area inside WHTZ 54dBu Service Contour
WLTW FCC F(50,50) 54dBu Service Contour
Area inside WLTW 54dBu Service Contour
WHTZ -20dBc
¼ Wave Antenna
WLTW -14dBc
¼ Wave Antenna
Slide25New York City – Empire State Building
WHTZ FCC F(50,50) 54dBu Service Contour
Area inside WHTZ 54dBu Service Contour
WLTW FCC F(50,50) 54dBu Service Contour
Area inside WLTW 54dBu Service Contour
WHTZ -20dBc
OEM Antenna
WLTW -14dBc
OEM Antenna
Slide26New York City – Empire State Building
WHTZ -20dBc
¼ Wave Antenna
WLTW -14dBc
¼ Wave Antenna
Slide27New York City – Empire State Building
WHTZ -20dBc
OEM
Antenna
WLTW -14dBc
OEM Antenna
Slide28Los Angeles – Mount Wilson
Los Angeles, stations running elevated digital power are difficult to find.Most
of the stations in Los Angeles are on Mount Wilson and operate as grandfathered super-powered
stations.
Licensed
as Class B FM stations, but generally have analog ERP and HAAT values far in excess of class
facilities.
Under the provisions of the Third Order, there is room for some grandfathered stations to increase power, but the majority of the stations on Mount Wilson do not qualify
and are capped at -20dBc.
Many areas of Los Angeles are underserved by stations running
at -20dBc.
Slide29Los Angeles – Mount Wilson
While many of the stations on Mount Wilson are grandfathered super-powered stations, their facilities are not equivalent. Each station has a unique ERP and HAAT combination that varies from 0.4dB to more than 18dB above Class B maximum facilities.
Since almost all of these stations are capped at
-20dBc
, some stations on Mount Wilson perform better than others in the digital realm because they are grandfathered at higher power
levels.
I often compare KBIG and KIIS, as they represent two widely different power levels. KBIG has one of the highest digital ERP values on Mount Wilson, and KIIS has one of the lowest of the grandfathered stations. The results between the two in the field are quite noticeable.
Slide30Los Angeles – Mount Wilson
While the list of all the stations is too large to publish, the stations that Clear Channel operates from Mount Wilson are summarized below:
The power difference between the highest powered digital facility
(
KBIG) and the lowest value (KIIS) is 9.1dB.
Station
Freq.
(MHz)
Class
Analog
ERP
(kW)
HAAT
(Meters)
Digital ERP
(Watts)
Digital
Level(dBc)KBIG104.3B65928650-20KHHT92.3B42887420-20KOST103.5B12.5949
125
-20
KIIS
102.7
B
8
902
80
-20
Slide31Los Angeles – Mount Wilson
Burbank KIIS -20dBc (-9.1dB KBIG)
¼ Wave Antenna
Burbank KBIG -20dBc (+9.1dB KIIS)
¼ Wave Antenna
Slide32Los Angeles – Mount Wilson
Orange County
KIIS -20dBc (-9.1dB KBIG)
¼ Wave Antenna
Orange County
KBIG -20dBc (+9.1dB KIIS)
¼ Wave Antenna
KIIS FCC F(50,50) 54dBu Service Contour
KBIG FCC F(50,50) 54dBu Service Contour
Slide33Discussion
The increase from -20dBc to -14dBc is significant and has created improvements, it seems to always fall
short in replicating a station’s analog coverage.
Most other forms of entertainment have transitioned to digital.
In
order for radio broadcast services to remain relevant, the conversion to digital must continue
.
Exciting new services are being offered via HD Radio technology and those services are being implemented by
automotive manufacturers
today
.
These
new features are important to keep radio relevant and competitive with other digital technologies in the car.
Millions
of new HD Radio receivers are on the marketplace and
are being
sold in automobiles each year and that trend is sure to continue.
As more consumers obtain HD Radios, they will find that the coverage is not comparable to what they had in the analog realm.
Slide34Discussion
Even with the blanket -14dBc power level, there are still areas in every market that I have analyzed that could use additional digital power to be at par with analog
coverage expectations.
While the elevated power level of
-14dBc
has resulted in significant improvement, there still may be benefits of an even higher power level of up to
-10dBc.
The
results submitted by
iBiquity
in 2007 and 2008 show that
-10dBc
is compatible in most situations.
Research
in this area has remained dormant for several years.
I
suggest that, in light of research showing
-14dBc is not always adequate, perhaps -10dBc coverage and interference studies should be re-evaluated.
Slide35Discussion
In the 2010 Third Order, the Commission stated “The Bureau’s experience with higher powered digital experimental authorizations suggests that the
formula…
is over-predictive of the potential for interference
.”
To
date, with more than 365 stations operating at elevated digital power levels, no interference complaints have been received
.
Not
a single station has been ordered to reduce digital power or cease digital
operation.
Unfortunately, this restrictive formula in use has effectively slowed the progress of digital radio advancements
.
In order for digital radio to be successful, and for this industry to continue to thrive and remain competitive in an era of increased competition from a variety of other digital entertainment options, I feel that it is very necessary to re-evaluate digital power levels once
again.
Slide36Discussion
We now have over four years of elevated digital power operations under the new rules. The record of elevated power stations extends as far back as seven years.
There
have been
no
interference complaints
processed under the rules
.
Yet
, many complaints are logged by people regarding the underperformance of their digital radios.
Those
complaints and the dissatisfaction of listeners will only increase as millions of additional digital radios are sold each year.
If
current trends continue, by the end of the decade, digital radios will reach critical mass. I feel the industry is woefully under prepared for how
inadequate -14dBc
coverage can be.
Slide37Discussion
I hope that this research sheds some new light on Elevated FM IBOC Performance at the -14dBc power level.
Perhaps we as an industry can work together constructively to research the implications of lifting some of the restrictions and encourage wider adoption of more meaningful power increases up to -10dBc.
Let’s start
a dialogue on how we can
devise
some relaxation in the rules to allow for some meaningful power increases in the super-powered heavy markets of Los Angeles and San
Francisco.
Or
at least start to level the playing field for those grandfathered stations which are now suddenly far less competitive than some of their other in-market peer stations.
Slide38Discussion
Use the interference resolution procedures outlined in the Third Order (or some mutually agreeable update of them) to regulate any interference complaints. In the past seven years, there have been additional technical improvements on the transmission side
.
Using today’s technology, converting a station that went to
-10dBc
back down to
-14dBc
is a few touchscreen commands away
.
It is simple to do, and if the complaint is related to just one adjacency, let us allow asymmetrical sideband technology be used as a way to mitigate any interference complaints that may come to
light.
Slide39Conclusion
Digital radios will become standard equipment in most automobiles within the next few years. HD Radio will become the normal listening platform for the public, and they will demand that it work properly and in the same areas they are used to enjoying analog FM service, or they may move on to other digital mediums that are deemed more reliable or
consistent.
Why
should we hold back and harm the entire industry from having a successful digital transition based on concerns that still to this date have not materialized
?
Let
us ensure there are safeguards in place to mitigate any interference on a case by case basis.
The
time has come for additional research, evaluation, and discussion on
-10dBc
digital operation.
Slide40Acknowledgements
Elevated power numbers and information obtained by the Federal Communications Commission current as of January 7, 2014. Information provided by Janice Wise and Susan Crawford.
Special thanks to Russ Mundschenk, et. al. at
iBiquity
Digital Corporation for providing suggestive measurement techniques to perform more in-depth coverage analysis of OEM antenna designs.
Slide41Field Observations of Elevated FM HD IBOC Power Levels
Questions?Please review the white
paper for more
detailed analysis.