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Our readers speak up

Our readers speak up

Jul 1, 2002 12:00 PM

Improve the receivers, not the transmitters

Regarding IBOC-AM [from the thoughts presented by John Batison in the May issue], I think that stereo analog AM to 15kHz with DSP would be the easiest, fastest and best way to go. I am opposed to the use of the Ibiquity IBOC-AM systemfor the following reasons:

� IBOC-AM is incompatible with the FCC�s approved Motorola C-Quam AM stereo broadcasting system in use at over 300 stations in the United States. (Reference FCC ET Docket 92-298 / FCC 93-485 / 8 FCC Rcd 8216).

� IBOC-AM is not totally backwards compatible with all existing high-quality AM radio receivers with a bandwidth exceeding 5kHz (such as GM Delco UX-1 car radios). Ibiquity IBOC will occupy more bandwidth (15kHz) than the current NRSC 10.2kHz limit, causing interference.

� The Ibiquity IBOC-AM system will be unusable during nighttime AM broadcasting as skywave reception will render their digital signal useless in many areas.

� The Ibiquity IBOC-AM system would substantially lower the quality of existing analog AM broadcasters, who currently can broadcast their audio with a +/-3dB frequency response out to 10.2kHz and would require them to degrade their audio to a poor telephone-like 5kHz frequency response. This is totally unacceptable to degrade the analog audio to make the digital sound better.

� Other types of digital enhancements can be added to all new analog AM receivers, which would incorporate Digital Signal (DSP) processing, noise blanking in both the I.F. and audio stages, and DSP reception of analog C-Quam AM stereo transmissions.

� I have used a Sony AM stereo home receiver, a Delco automobile radio, and a Chrysler automobile stereo unit, all of which feature analog AM stereo. These high-quality receivers can each receive radio station WJR-Detroit (760kHz) with �FM-like� stereo quality – in fact, sometimes reception is better than many of the local FM stations in terms of audio quality and stereo separation. With the digital enhancements listed in item #5, particularly noise blanking, the reception of analog AM stereo stations would sound even better.

� The AM broadcast band should remain analog indefinitely as a legacy or heritage radio service for the American public. Not only are there hundreds of millions of AM receivers in use, but more importantly, in times of crisis or emergency, an analog AM receiver (crystal radio) can be constructed from just four common electronic items (ferrite antenna, diode, tuning capacitor, earphone) providing emergency reception.

� The FCC should mandate that all new technology to be 100 percent backwards compatible so as not to obsolete receivers. The FCC was very insightful and responsible to make NTSC color TV compatible with black and white televisions; FM stereo is compatible with mono FM radios; C-Quam AM stereo is compatible with mono AM tuners; NTSC TV stereo and SAP is compatible with mono TV receivers. The proposed IBOC-AM would cause digital noise in the better quality AM tuners, and is therefore not 100percent compatible with existing receivers. The FCC must continue to mandate all technical standards for broadcasting in the US, as that is its major role to the American public.

Here are my suggestions for immediately improving the technical quality of AM radio here in the United States without an expensive transition to the proposed IBOC-AM system:

1. Encourage receiver manufacturers to incorporate AMAX receiver standards in all future AM radio receivers (wider bandwidth, noise blanking), and to clearly label these new receivers with AMAX or AMAX-Stereo if so equipped. In fact, manufacturers could identify the band switch not as AM (or FM), but as AMAX (and FM).

2. Encourage receiver manufacturers to utilize digital enhancements all new AM receivers, such as Digital Signal (DSP) processing, noise blanking in both the I.F. and audio stages, and DSP reception of analog C-Quam AM stereo transmissions.

3. Encourage all AM stations to install, or turn-back on, C-Quam AM stereo equipment, particularly those with a music format such as WSM, and WSAI.

4. Have the FCC enforce all Stereo AM broadcasting for all Expanded Band stations (1610 to 1700kHz) that indicated a �stereo preference� for their station, to commence stereo AM broadcasts within one year.

5. Have the FCC request, or require, all AM Class-A clear channel stations to commence or restart C-Quam stereo AM broadcasts within one year. Note: many of these Class A Clear Channel stations already have the stereo equipment in operation (such as WGN, WJR, WLS, WBAP, WPHT), or stereo equipment is installed, but currently turned-off at the present time (at stations such as WFAN, WCCO, WHAS, WBZ, KMOX).

6. I suggest that the FCC should require digitally-tuned FM stereo receivers to also include AM stereo meeting AMAX standards. This would not apply to analog tuned, or FM mono radios. Please reference an FCC petition document awaiting a docket number, entitled Petition for Mandatory AM Receiver Standards submitted by Scott Todd.

I suggest that the FCC enforce, or encourage, enhanced analog AM radio transmitter and digital signal processing receiver improvements as listed above, that will be 100 percent compatible with all existing AM receivers.

John Pavlica
systems engineer
nnovative Controls Corporation
Toledo, OH

Mr. Pavlicka also provided a website listing of most of the AM stereo stations in North America:

Always more online

I just wanted to thank you for making back issues, and for that matter, current issues available online. It�s a great service that allows me to make printer-friendly copies for the files. Thanks.

David Green
chief engineer
Fort Worth, TX

Who�s counting?

Hi Chriss,

I just read your [Viewpoint in the May issue]. It is interesting that every time someone reports that a trade show (in any market niche) had low attendance, the next statement is inevitably, �…but the people that were there were all quality leads.� Personally, I think accurate attendance statistics are the only meaningful measure of the success of a trade show. The theory that those who did not attend are �just tire kickers,� is not credible. If this were true, corporate spending would remain constant. Clearly, this has not been the case throughout the U.S. economy.

Your point on the inflationary counting method is well made, but certainly not exclusively practiced by the NAB. I hope that trade associations, like public corporations, will take part in the trend of more accurate disclosure. This would solidify their credibility and longevity.

Joe Ciaudelli
director of marketing
Sennheiser Electronic
Old Lyme, CT

Stellar STL report

I just read your article on STLs [May 2002]. I�d like to thank you for a balanced and informative article. You�re right�STLs aren�t glamorous, but their 24/7 operation is critical to any broadcast facility.

There are two items I thought worth mentioning. In your discussion of T1 and E1 multiplexers, you said, �Most manufacturers offer various encoding cards in addition to those for linear encoding.� Please note that the encoder and decoder cards supplied with Musicam USA TEAM systems support all algorithms, since the DSP code is stored in the TEAM�s Control Processor Module and is downloaded to the appropriate module on demand. This makes it possible swap algorithms as necessary, even as part of a broadcast day.

The second item relates to the issue of backup. Our TEAM system supports automatic backup via ISDN. With one or more ISDN Modules installed, a TEAM can automatically reconfigure its mapping, dial an ISDN number and retrieve audio via ISDN when the T1 or E1 line fails. Then, when the wideband line is restored, the TEAM politely hangs up and reverts to normal operation.

Art Constantine
VP, Business Development
Corporate Computer Systems, Inc., d/b/a Musicam USA
Holmdel, NJ