Why a Full 10 dB Increase Is Necessary
     


This paper examines the results of elevated HD Radio carrier power tests performed by Charles River Broadcasting with the assistance of iBiquity Corp. This information was filed with the FCC by Charles River Broadcasting and iBiquity on July 6. The testing program explored the performance of elevated HD Radio carrier power in comparison to the currently authorized –20 dBc carrier power for both mobile and indoor reception conditions.

MOBILE RECEPTION TESTS BACKGROUND AND OBSERVATIONS

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Fig. 1: FM Hybrid IBOC Spectral Test mask @ –10 dBc
On Dec. 4, 2008 Charles River Broadcasting Co., licensee of WKLB(FM) Waltham, Mass., and a subsidiary of Greater Media Inc., was granted experimental authority by the FCC (file number 20081031ACO) to operate with digital carrier levels up to and including –10 dBc.

This permitted WKLB to operate with digital power levels up to and including 10 dB above that currently permitted by the commission’s rules.

WKLB has operated at various elevated digital power levels during the duration of the experimental authority and recently filed an interim report with the commission, coincident with its request for an extension of such authority, detailing its observations during this period. It was noted in the interim report that WKLB would shortly be conducting additional testing to better quantify the actual improvements occasioned by operation at the elevated digital power levels.

During the past month, Charles River, with the assistance and cooperation of iBiquity Digital, the developer of the HD Radio system, has conducted extensive field testing in an effort to quantify improvements in the WKLB digital service occasioned by increasing power to several discrete levels. Although a number of studies have been previously submitted detailing coverage improvement over a specific route or routes, it is believed that this is the first to comprehensively quantify such improvements over an entire metropolitan area.

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Fig. 2: Typical FM Hybrid IBOC Spectrum @ –10 dBc
Four heavily traveled radials routes (I-90, I-93, I-95 and State Route 3) and a circular “beltway” (I-495) that encircles much of the Boston metropolitan area were chosen to gain knowledge of digital signal improvements over the entire market. The mobile test platform employed was identical in equipment and configuration to that used for the initial NRSC testing in 2002 and for the more recent testing conducted on Greater Media stations WRAT, WJRZ, WDHA and WCSX as well as several other non-Greater Media owned facilities. Results of these tests have been previously submitted to the commission over the course of the digital radio proceeding.

A JVC Model KDHDR50 receiver was used to determine whether digital reception was possible at any point on a route. This receiver was previously characterized as being “typical” and meeting its published performance specification by iBiquity. Data as to time, location, spectral content and reception mode (analog or digital) was recorded on a micro computer using a proprietary iBiquity data collection program. The receiving antenna was a conventional 31-inch whip mounted in the center of the test vehicle roof (see Fig. 4).

Fig. 3: Dual-Input Antenna

Fig. 4: Mobile Test Platform

All data on each route, for each power level was recorded with the test vehicle proceeding in the same direction. The data collected represents several thousand miles of vehicle operation.

Test Description

For these tests, the system operated in the hybrid mode, which contains the analog FM signal and service mode MP3 digital carriers.

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Fig. 5: WKLB @ –20 dBc (–19.21 dBc in Mode MP3)
Fig. 1 shows the digital carriers at 10 dB below analog power levels with both the FCC and iBiquity masks. The digital sidebands will exceed the current iBiquity mask by about 8.5 dB. The digital sidebands comply with the FCC mask.

Fig. 2 shows the RF spectrum from the forward sample port of a dual-input transmitting antenna, and the iBiquity spurious noise and emissions mask. As shown in Fig. 1, the sideband power exceeds the current iBiquity digital mask in the frequency range of ±129 to ±199 kHz. Even at the –10 dB power level, the IBOC transmitter is capable of meeting or exceeding the iBiquity mask thresholds established for the –20 dB power level.

Transmitter Test Site

These tests were conducted using the RF transmission facilities of WKLB, Waltham, Mass. (Boston). WKLB was granted experimental authority under 47CFR 73.1510(d) to operate with digital power levels up to and including 10 dB above currently authorized levels.

Please note that WKLB’s total integrated digital power is increased by 0.79 dB over the reference –20 / –14 / –10 dBc levels to accommodate the additional carriers present in transmission Mode MP3.

Transmission Facility Information
FCC Facility ID: 10542
North Latitude 42° 18’ 37”
West Longitude 71° 14’ 14”
High-Power IBOC authority per 47CFR 73.1510(d) granted 12/4/08


Radiation Parameters
AGL 290 m
G AMSL 30 m
RC AMSL 320 m
HAAT 272.27 m
ERP (Analog) 14.0 kW
ERP (Digital) 167.91 W (–19.21 dBc D/A Ratio – Mode MP3)
ERP (Digital) 670.17 W (–13.21 dBc D/A Ratio – Mode MP3)
ERP (Digital) 1679.1 W (–9.21 dBc D/A Ratio – Mode MP3)


Antenna
ERI Model 1183-4CP-2 Dual-Input Hybrid IBOC (see Fig. 3)
Operating Power

For these tests, WKLB chose to operate each transmitting facility at various total power levels from 20 dB to 10 dB below that of the reference analog carrier. The digital to analog power ratio was verified using digital power meters and transmission system loss/antenna gain calculations supplied by the equipment manufacturers.

Mobile Reception Test Results

Referencing Fig. 5, it can be plainly seen that at the currently authorized –20 dBc power level there are significant and serious digital coverage deficiencies within the WKLB 54 dBu protected analog contour on all routes measured.

It should be emphasized that the “cliff edge” propagation characteristics of digital signals, and specifically IBOC digital radio signals, make any loss of the digital signal, even momentary, extremely irritating to the listener. The effect is not one to which a listener is accustomed, such as multipath or picket fencing, where the audio is still available, albeit compromised. A listener to an HD-1 channel will sense a fall back to the underlying analog signal, which is likely blended to mono and/or experiencing high-frequency roll-off resultant from circuitry included in virtually every analog auto radio, resulting in the loss of stereo perspective and a significant decrease in fidelity.

The situation with HD-2 and HD-3 channels is worse; the signal is simply gone. More than an extremely occasional instance of any such impairment will cause listeners to seek another audio entertainment option.

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Fig. 6: WKLB @ –14 dBc (–13.21 dBc in Mode MP3)
A close examination of each route will show multiple and numerous instances of intermittent loss of digital service, even prior to those areas where digital service is largely absent.

Fig. 6, representing service at –14 dBc (6 dB above the currently authorized digital power level), shows significant improvement on all routes but also shows evidence of occasional losses of the digital signal within the underlying analog 54 dBu protected contour, again even prior to those remaining areas where the digital signal is more seriously compromised.

Attention is directed to I-93 (between I-495 and the 54 dBu contour), I-495 (from I-93 to the 54 dBu contour) and even I-90 (immediately west of I-495). All these areas exhibit multiple momentary digital signal dropouts, well within the analog coverage area of WKLB. Clearly, operation at –14 dBc provides significant improvement, but fails in terms of replication of analog signal coverage, an absolute requirement if digital radio is to be the successor to that service and the key to listener satisfaction and acceptance.

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Fig. 7: WKLB @ –10 dBc (-9.21 dBc in Mode MP3)
Fig. 7, representing service at –10 dBc (10 dB above the currently authorized digital power level), shows marked improvement in digital service, as compared to Fig. 2. Other than terrain shadowed area in the Providence/Pawtucket and Plymouth areas, digital reception is virtually flawless over the various routes.

It is extremely important to observe, other than those areas just noted, there are virtually no areas where any momentary digital signal drop outs are evident. This is the level of service a listener anticipates and expects. This is the level of service necessary to ensure the continuing successful roll out of digital radio.

Mobile Reception Conclusions

Clearly, digital radio service at the currently authorized power of level of –20 dBc does not come close to providing the robustness and quality of service anticipated and expected by listeners, based on an analog reference point. This first-of-its-kind survey of an entire metropolitan area proves that fact beyond any reasonable doubt.

Station operation at –14 dBc, a four times digital power increase, substantially improves digital coverage but still does not provide either flawless digital service nor replication of the underlying analog service area, two very basic and critical listener expectations.

Station operation at a –10 dBc level, as proposed by the joint parties, does result in largely impairment-free coverage and replication of analog service. It is critical to understand that the failure mode of a multicast digital radio signal is dramatic and unfamiliar to a listener, representing a total loss of service. Such irritants must be absolutely minimized if listener expectations are to be met.

These maps show significant shortfall in coverage for the important suburban Boston communities of Lowell, Andover, Lawrence and Haverhill, Mass. to the north and Plymouth, Mass., Pawtucket and Providence, R.I., to the south. In addition, numerous areas of the heavily traveled Rt. 495 “beltway” experience severe dropouts of the HD Radio signal. It is apparent that WKLB cannot deliver commuters acceptable digital service at a power level of –20 dBc.

Increasing the digital power by 6 dB (to –14 dBc) dramatically improves the HD Radio listener’s experience on heavily traveled Rt. 495. Beltway commuters north of Lowell and south of Attleboro can now receive WKLB’s multicast programming without interruption. Coverage in Pawtucket and Providence improves, but dropouts of multicast reception here will cause listener tune out. Vacationers stuck in Cape Cod weekend traffic on Rt. 3 will likewise lose the WKLB multicast signal.

A full 10 dB digital power increase (to –10 dBc) appears to be the solution to most WKLB mobile reception issues. The only areas still compromised are low spots in Plymouth, Pawtucket and Providence.

FM HD RADIO SYSTEM PERFORMANCE IN BUILDING INTERIORS AT ELEVATED DIGITAL CARRIER LEVELS

Although at least one previous study (conducted by CBS Radio) has been completed pertaining to the relative ability of digital signals — at various power levels — to achieve penetration of structures, it is believed that the instant report adds appreciably to that body of knowledge and expands the universe of receivers to include the newly released Insignia NS-HD01 battery-operated portable HD Radio Receiver.

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Map 1: Site Map for Building Interior Reception Tests
Observations were made in a number of varied structures representative of the majority of those in the Greater Boston area and, indeed, the entire United States. Six different locations were selected to be representative of the most common types of building construction.

Location 1, the Greater Media studio building in the Dorchester section of Boston, is representative of low-rise (two-story) masonry, steel and glass construction. Location 2, The Caning Shop in the Cambridge section of Boston, is a single-story structure (with an occupied lower level) of wood and masonry construction. Location 3, the Prudential Tower, in the Back Bay section of Boston, is a high-rise skyscraper of steel, aluminum and glass construction. These locations (1–3) are all located within the urban core of Boston, within 8–10 miles of the WKLB transmission facility in Needham, Mass. (see Map 1).

Even though none are farther than 10 miles from the WKLB transmitter site, they all potentially can suffer from the “urban reception dilemma.” Since many commercial buildings are metallic construction, shadowing, reflection and parasitic re-radiation of the HD Radio signal can cause it to fail. Excessive urban electrical noise only augments the problem.

Location 4 is a typical two-story, split-level residence in Andover, Mass., of wood frame construction. Location 5, the headquarters of the Comrex Corp. in Devens, Mass., is a two-story steel-framed, wood building typical of many small- to medium-size commercial structures. Location 6 is a three-story apartment building in North Attleboro, Mass., of poured concrete (with rebar) construction. Locations 4–6 are located at approximately the edge of digital coverage assuming the currently authorized –20 dBc power level.

Receiver Equipment and Test Procedures

Two receiver models were used in the testing. A Sony XDR-S10HDiP table radio, one of the better-performing receivers of this genre, was used for evaluation at numerous fixed locations within each structure. As many as four of these receivers, operated with associated manufacturer supplied antennas, were utilized simultaneously to characterize reception at various locations within each structure. The radio was connected to the supplied dipole antenna, supported vertically by a custom-made stand of PVC pipe. The manufacturer’s antenna uses about 6 feet of unshielded twin-lead feeder cable. This cable not only acts as part of the antenna, but tests in iBiquity’s semi-anechoic chamber showed losses of up to 8 dB over a reference dipole fed by coaxial cable. Nevertheless, the manufacturer’s antenna was used in an effort to replicate the listener experience.

The second receiver, the Insignia NSHD-01 portable, was operated as it would be by a typical user, being moved about the interior of each structure to ascertain the availability of digital radio reception. All receivers were characterized in the iBiquity Digital laboratory to verify that each met its published specifications.

Observations were made at each receiver, at each location and at each incremental power level to ascertain the availability of digital reception. In the case of the table (Sony) receiver, reception was characterized as “analog,” “flashing,” or “100%.” “Flashing” indicated illumination of the HD mode indicator but not actual digital reception. “100%” indicated reception of the digital signal. In the case of the portable receiver, the approximate availability of digital reception, as expressed as a percentage, was noted as the receiver was moved about the area of interest.

Actual field strength was documented at each test location as well as at the exterior of each of the six structures evaluated. FM analog field intensity was measured in dBuV with a Z-Technology model R-507 field intensity meter connected to an ETS-Lindgren model 3121C-DB2 calibrated dipole antenna whose elements had been adjusted to the proper length. The antenna was used in vertical polarization only to minimize h-pol directional effects. An average reading was obtained by slowly moving the calibrated antenna of the Z-Technology field intensity meter in a one meter square area around the test location. The test antenna was removed to prevent measurement error due to parasitic coupling of elements.

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To determine the point of digital signal acquisition, up to four Sony radio receivers were placed randomly around each of the test areas. The digital power was increased in 2 dB steps from –20 dBc to –10 dBc until the radio solidly locked onto the digital signal. The point of digital signal acquisition was tabulated for each receiver.

Test Results by Location

Referencing Location 1 (see diagram), it can be plainly seen that as one moves further into the interior of this building, digital reception becomes in¬creasingly impossible at the – 20 dBc power level. Further, reception by the portable armband receiver is virtually nonexistent at any location within the building at the currently authorized power level. Keep in mind that this location is less than 10 miles from the class B transmission facilities of WKLB(FM).

Increasing the digital power level to –12 dBc results in digital reception by the table radio at most location but –10 dBc is required to achieve any effective reception by the portable receiver.

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At Location 2, HD reception is possible at –20 dBc on the first floor level of the structure. However in the occupied basement level there is no HD reception whatsoever. At –14 dBc reception at this location improves to 75 percent but –12 dBc is required to achieve 100 percent reliability on the tabletop receiver and –10 dBc is required for seamless reception on the portable (see Location 2 diagram).

Location 3, on the 26th floor of the Prudential Tower Building, with direct line of sight to the WKLB transmitter site in Needham, exhibited relative high levels of signal within the surveyed space resulting in good reception on the table radio in all areas with direct exposure to the large exterior windows. As one moved further into the building interior, increasingly higher levels of signal were required to maintain digital reception, with –16 dBc being necessary for digital reception at the building core.

Performance of the portable receiver was appreciably worse. At the –20 dBc power level only 50 percent digital coverage was achieved in the space surveyed, with –10 dBc being required to achieve 95 percent coverage (see Location 3 diagram).

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At the Andover residence, Location 4, reception varied, as would be expected, depending on which floor (and thus which elevation) was surveyed. On the second floor, 100 percent HD reception on the table radio was achieved at –14 dBc while the armband receiver required –10 dBc for 85 percent digital reception. However on the first floor –10 dBc was necessary to achieve seamless reception on both the table and armband radios. At the basement level, –10 dBc was likewise necessary to achieve reliable table radio reception. The armband radio only achieved 20 percent reception at even the –10 dBc power level (see Location 4 diagram).

At the headquarters of Comrex, Location 5, reception was again somewhat dependent on the floor level surveyed. On the second floor, a digital power level of –14 dBc produced acceptable reception at most fixed receiver locations (–10 dBc was required for seamless reception at all locations) while on the first floor only –10 dBc resulted in reception at 50 percent of the locations. Reception by the portable receiver improved from 10 percent to 80 percent on the second floor and from 1 percent to 65 percent on the first floor with a digital power increase of 10 dB (see Location 5 diagram).

Location 6, an apartment building in North Attleboro, exhibited no HD reception on any receiver at any location at the –20 dBc digital power level. In every case, –10 dBc was required to achieve digital reception on the table radio and to achieve reception at roughly 50 percent reliability on the portable receiver (see Location 6 diagram).

STRUCTURE TYPE ATTENUATION CHARACTERIZATION

Review of the data shows that the greatest amount of structural attenuation occurs in metallic buildings, or those using metal in construction. Visible metal such as window mullions as well as hidden building superstructures and concrete reinforcing rods all can potentially reflect or direct the RF signal.

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The Greater Media Studio building (Location 1), the 26th floor of the Prudential building (Location 3) and Residence #2 (Location 6) all demonstrate the above. Additionally, concrete and steel apartment buildings (Location 6) easily render the HD Radio signal not receivable in core units. Wood frame dwellings and offices (Locations 4 & 5) without metalized vapor barriers or aluminum siding, on the other hand, do little to block the FM signal. Likewise, concrete block structures without metal reinforcement (Location 2) have minimal effect on reception.

Real-World Collateral Effects

If it is true that poured concrete structures present such a barrier to FM HD Radio signals, then the core of daytime in-office listeners will be cut off from their favorite multicast HD Radio programming (and any revenue generating advertising).

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It seems reasonable to assume that office workers who are blocked from HD Radio reception at their desk or on their armband radios would drive home listening to their favorite format, only to be barred from reception in their apartment.

Listeners using a portable “armband” type HD Radio receiver can expect dropouts as they walk around the workplace, even in areas characterized by a high outdoor signal level. Armband radio listeners on the 26th floor of the Prudential Tower can only expect solid HD Radio reception if the transmitter is operating at a full –10 dBc digital-to-analog ratio.

Indoor Reception Conclusions

As can be readily ascertained from the test report and these comments, building penetration and thus the ability of listeners to readily receive digital radio signals in their workplaces and their homes is a significant challenge at today’s –20 dBc digital power level.

Put more bluntly, in many building types, digital reception is simply impossible on well-performing table model receivers and similarly nonexistent on the new class of portable receivers about to be introduced into the market place.

Although an incremental digital power may serve to partially mitigate the situation for plug-in receivers in some fixed locations, only a full 10 dB increase will permit reliable service to portable receivers and result in a close approximation of analog coverage, two very basic and critical listener expectations.

Russ Mundschenk is field test and implementation manager for iBiquity Digital Corp. Milford Smith is vice president of radio engineering for Greater Media Inc.

Comment on this or any other article at
rwee@nbmedia.com.


Rating People: 2   Average Rating:     
Comment List:

Get your facts right. Let’s start with the Radiosophy fiasco, then Sony and work our way all the way to the Insignia. It doesn’t sell screw ball. By the way, you’re not PocketRadio - nice try. That’s pretty low. You must work for iBiquity and I know you’re in panic mode. Check you history as well. FM didn't displace any existing service like your beloved HD radio does. Bad, bad comparison but I know you foolish people use it ignorantly.
By Your Not PocketRadio on 10/22/2009
Hey, great article, I alway follow Charles River Broadcasting to get the news first! Also, sometimes I find his articles at http://www.pdfok.com/charles-river , they always raise my mood!. Regarding this very aarticle, I really must say that digital reception is really impossible on well-performing table model receivers and also nonexistent on the new class of portable receivers about to be introduced into the market place. That's how it is.
By Symon on 8/17/2010
I'm sorry but did I miss something? Didn't Struble say a few weeks back; "And we can all agree that 6dB would hurt anybody". What happened to that disclosure? And what about his admission that he wants to "be mindful" of people who want further testing and who are concerned with adjacent channel interference? What trash basket did that comment go in? This is getting to the point of absurdity. and RW is looking as foolish as iBiquity.
By Sam T. on 10/21/2009
PocketRadio is not PocketRadio the HD Radio Farce - LOL!
By PocketRadio NOT on 10/22/2009
"Fact is, hd radio doesn’t sell. Consumers have spoken this for 7 long years but that doesn’t seem to deter the proponents." HD radio has only been seriously marketed for 2 years. FM took 20 plus years to catch on. Thousands of successful products and services took a long time to catch on. The amount of time it takes to catch on is not a good indicator of its future success. Looking at this from another perspective: Wait for it to become mainstream in auto head units and then ask those owners after a few years would they go back to analog? And let's have this conversation again.
By PocketRadio on 10/22/2009
Even I am starting to embrace HD radio.
By PocketRadio on 10/21/2009
This would make our FM band more useful - just like the class D citizens radio service is.
By Dave on 10/21/2009
FM wasn’t peddled by an out-of-control egomaniac like Struble and company. It was implemented intelligently (by a more capable FCC back then) and didn't take any service away. In other words, it added value unlike your digital failure. Consumers decided if they wanted it. Your argument is bogus. Do you actually work for living? I've got facts on my side. You don't.
By Bob E. on 10/22/2009
No-no-no! We gotta make this work boys, we just gotta. OK, lets propose asymmetrical transmission base on who's above and below our channel. Yeah, that's it! let's just make this a free-for-all! Asymmetry at various power levels at various locations, cities etc. Yeah, Yeah and the FCC will monitor it all to make it work. You people are in a dream world.
By Bill on 10/21/2009
You must live under the transmitter
By Anonymous on 11/21/2009
How many tmes can you hear 'Satisfaction' on several HD and analog, all at once?
By Anonymous on 10/24/2009
HD Sounds SO CLEAN compared to the 10 KHZ and 15 KHZ on the AM and FM band
By Anonymous on 10/23/2009
If the FCC had not packed the AM band with too many stations then it would sound good. If the FCC had not made a new rule (in 1989) limiting the audio on AM to ten kiloHertz then it would sound good. If the FCC had not changed its mind on which stereo system AM would use then AM would sound good. The FCC is the problem.
By Anonymous on 10/24/2009
Hey Mister - "HD Sounds SO CLEAN compared to the 10 KHZ and 15 KHZ on the AM and FM band". I'll bet I could play you analog FM and digital FM, side by side, and you couldn't tell the difference. Don't think so? I know so. You been reading to many RW articles.
By Anonymous on 10/24/2009
For a technology that I thinks sounds great to my untrained ears both AM and FM, I'm not sure why the strong anti-HD radio emotion from what appears to be a close knit niche group of HD radio haters.
By Anonymous on 11/2/2009
You are correct. The solution is a standalone digital service. Convincing the iBiquity apologists will be difficult if not impossible. They've made a career out of making excuses for their failed venture and blew millions of $$ pointlessly. Besides, it's a good gig for Struble so he's dragging it out as long as he can.
By Anonymous on 10/22/2009
I think the anonymous writer below has a great idea. There are millions of satellite receiver in use right now. These transmissions don't actually have to come from a satellite, many of them are from small repeaters in urban areas designed to fill in where the satellite transmission is blocked. Why not designate many of the open channels created as a result of the recent merger for terrestrial digital transmissions. A separate digital band is not spectrum inefficient, the Brits really did have a great idea, just slightly ahead of their time. Modern digital codecs can be d automatically. Have any of you tried to do a remote broad using iBuiquity time delay IBOC. It is very difficult, sloppy, and almost impossible for the average announcers. We are going to hear more "Cell Phone Remotes" rather than the former high quality RPU remote transmitter. Yes, modern DIGITAL cell phones sound terrible also. Digital television is a disaster for more than 10% of viewers. It is almost impossible to watch a digital B R O A D C A S T signal while mobile and fringe area reception is choppy at best. Many stations transmit with reduced bandwidth to add a second, third or even a fourth program channel, resulting in pixelated viewing. (Let's not even mention Com's excessive compression.) Most modern CD's even sound terrible, I despise digital, and especially excessive digital compression. If any of you want "pure HD", get it on the Internet where bandwidth is available. But all of this argument might be a moot point as WIFI and 4G could absolutely destroy terrestrial broading as we know it, digital or not. Sorry to reply anonymously, but my employer would not approve of my posts.
By Anonymous on 10/22/2009
The problem with most digital radio proponents is that in their zeal for hd radio they seem to willfully forget that radio is, and should be, consumer driven. You can always tell the proponents with their "screw you" attitude when challenged. Fact is, hd radio doesn’t sell. Consumers have spoken this for 7 long years but that doesn’t seem to deter the proponents. They come up with all kinds of excuses - not enough power, not enough receivers, not enough stations converted, consumers need to be "educated" and the list goes on and on. Simple fact here - except for a few out-of-control radio insiders HD radio just isn’t needed or wanted. Time to stop the excuses and the force-feeding tactics and move on.
By Anonymous on 10/22/2009
"There may be some small annoyances to get to that ultimate step (which is pure HD FM and pure HD AM)" Wow are you fooled. Yeah let's just trash millions and millions of receivers and "embrace' the "HD rollout" that us stupid consumers don't realize we need. You need a reality check dude. Are you that crazy guy from WOR New York?
By Anonymous on 10/22/2009
Our best hope is that iBiquity will run out of money soon so that Russ Mundschenk can get a legitimate job.
By Anonymous on 10/21/2009
Having several HD radios (including the new Insignia portable), I can testify that these tests accurately reflect my own experience of HD radio. The fact is that anyone for themselves can easily see (if for example, they live more than 20 miles from a Class B FM) that the current HD radio power levels are at a completely unacceptably low level. I am not really sure why so many radio-philes are so anti-HD Radio. My experience in listening for interference to first adjacents at the -10dBc level is that it is low enough in the protected contour of the "victim" station to not be noticeable unless one is trying to notice it. If you are a listeners that is knowledgeable enough to notice it, you should be also knowledgeable enough to purchase a HD radio to hear noise free and almost interference free reception if the full -10dBc is permitted. The end goal should be that all FM stations have HD radio transmitters and all listeners have HD radio receivers. 1st Adjacent channel interference would then become a thing of the past (because the IBOC FM channels interleave on 1st adjacents) We will not get to that stage if -20dBc is the highest power authorized, because of low customer satisfaction with reception. It's a chicken and egg situation. Change always entails some sacrifice. The sacrifice hear being a small minority of listeners trying to DX first-adjacents stations broading in analog only. The solution to this (HD radio) is here. Now let's do it right and not turn this into a compromise which benefits no one and not let analog FM experience the fate of the buggy whip.
By Anonymous on 10/21/2009
Can't you spell it's broad not broad.
By Anonymous on 10/21/2009
I'm not in the broad business, but I'm glad to see an article that shows the HD radio reception experience from the Joe Six-pack perspective. Joe Six-pack doesn't typically try to tune in first adjacents outside their broad area. when Joe Six-pack buys a HD radio, he wants more stations, noise free receptions. He does not want his station fading back from analog to digital which it does now at current power levels. The multi stations don't have a chance at the current levels.
By Anonymous on 10/21/2009
@ Anonymous - 10/21/2009 Having several HD radios. Give me a break. If consumers wanted it then they'd be buying the Insignia - which, in case you haven't noticed, they aren't. You're a radio insider - one of the ones wanting to force feed it upon the world and are under the misguided believe that all-the-world-must-be-digital which is patently B.S. You probably work for iBiquity. I have "real world" experience on my side, what's on yours?
By Anonymous on 10/21/2009
I'de like to know how many stations have the funds and headroom for ANY power increase - LOL!
By Anonymous on 10/21/2009
A new digital band for digital radio, now that is something that is even less likely to work commercially in the short term unless you give it 20 years. Not to speak of it being spectrum inefficient. Look at the UK for an example of what I mean - By the time the concept gained some traction, the audio codec was out of date and low quality for the amount of bits used. Now the Swiss are embracing IBOC. As a technology freak, I make no apologies for saying HD radio will eventually be the best thing for the radio band since FM. There may be some small annoyances to get to that ultimate step (which is pure HD FM and pure HD AM) But that still won't satisfy the CB nostaglists here.
By Anonymous on 10/21/2009
It doesn't matter if iBiquity runs out of money now or later, the US version of digital radio is a flawed technology as the digital transmissions interfere with the originators own analog signal. Many analog stereo receivers interpret the digital noise as a weak signal, and blend the stereo separation to mono. Obviously an increase in the digital signal level will exacerbate this problem, resulting in a substantial background noise in all analog reception. Is the goal to FORCE us to switch to digital due to noticeably poor fidelity analog signal? Just look what the reduced bandwidth broads did to the AM band, the audio sounds terrible. We need to shut off all Hybrid Digital "HD" transmissions NOW, and then institute a new digital only broad band, preferably in the 76 to 88 MHz range or our soon to be bankrupt satellite broad band.
By Anonymous on 10/21/2009
The key word and phrase here are "tests" performed and "with the assistance of iBiquity Corp." For Ibiquity to perform reputable and reliable "testing" is highly unlikely. To date, they haven’t been honest about anything concerning their digital radio scheme. IBiquity being involved in "testing" is like letting the fox in the hen-house - not a good idea if you want honesty.
By Anonymous on 10/21/2009

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