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King Lays Out “Critical Steps”

KTL president pushes for receiver “parity,” synchronous booster authorization

Tom KingThis is a longer version of a story we reported earlier here on the Radio World website.

Kintronic Labs President Tom King has suggestions for how the FCC can help revitalize the U.S. AM band; he promoted an “open letter” in which he asks AM broadcasters to speak out. Radio World’s marketing arm helped distribute it; our editorial staff was not involved. I share his comments here as part of our coverage of the AM revitalization issue.

Few tech companies have an investment in AM as longstanding as that of KTL. The company markets itself as the oldest continually operating AM antenna system provider in the U.S. Founder Louis King resigned from RCA as an AM transmitter design engineer in 1949 and established a business as a consultant that grew into Kintronic. For more, read our 2007 profile, when the late Louis King received NAB’s Radio Engineering Achievement Award.

Below is Tom King’s open letter:

Kintronic Labs is concerned about the declining position of the AM radio service in the United States, which we reflected in our Reply Comments to the FCC NPRM Docket No. 13-249 on the subject of “AM Revitalization,” issued on Oct. 31, 2013. In the interest of preserving this great national resource for local public media, we have scheduled a meeting with FCC Commissioner Ajit Pai and Audio Media Chief Mr. Peter Doyle, to address what we believe are the critical steps toward putting AM radio on a more competitive basis with FM as follows:

(1) FCC enforcement of regulations relative to the power distribution industry and the consumer electronics industry that are not currently being enforced, resulting in a constantly worsening electromagnetic environment for AM radio service.

(2) The need for parity between AM and FM receivers through the establishment of minimum technical standards for AM receivers that would become effective as soon as January 2016. We plan to demonstrate a comparison of full-bandwidth C-QUAM AM stereo reception with a local FM station and with a typical AM receiver in a popular consumer multi-band receiver. The effects of adjusting the AM bandwidth from 2.5 to 10 kHz in 2.5 kHz steps will also be demonstrated.

(3) The need for FCC authorization of AM synchronous boosters. Unlike FM translators, such on-channel boosters would serve to increase the AM stations’ audiences while concurrently maintaining the future viability of the band. The related technique of wide-area AM synchronization for coverage improvement will also be addressed.

Referring to Step #2, it is absolutely essential that very close to full parity be established for new AM radio receivers vs. their FM radio counterparts. This includes all key AM receiver performance attributes, including:

Low internal noise floor, well below the average AM-band atmospheric noise level. This includes all internal synthesizer and DSP circuitry within the receiver (and in the immediate environment for integrated automotive applications).

High overall RF sensitivity, selectivity and dynamic range, to provide adequate amplification of weak signals, even in the presence of significant adjacent- and/or alternate-channel signals, especially in strong-signal environments. This would incorporate typical advanced, multi-stage AGC action, with appropriate interaction between the RF and IF AGC control mechanisms to maximize overall receiver dynamic range, including adaptive front-end attenuation for signal-overload protection in very strong-signal areas. Useful typical specs include sensitivity 1 mV for 10 dB SNR; selectivity (adjacent-channel) 25–50 dB (adaptive).

Highly effective noise (EMI) rejection, including staged RF and IF noise blanking, accompanied by appropriate audio blanking and/or expansion when required. Such features were developed and included in Motorola chip sets in the 1990s in the AMAX program, and are easily integrated into modern, high-density AM/FM receiver chips.

Full 10 kHz audio bandwidth capability with low detector distortion. This would obviously incorporate dynamic, signal-controlled bandwidth control (including AMAX-style adaptive 10 kHz notch filtering) as dictated by noise and adjacent-channel interference.

Stereo capability. If the receiver has FM stereo capability, it must have corresponding C-QUAM decoding for AM.

Without fulfillment of the first three requirements (this also includes the associated AM antennas both for vehicles and for home use), basic AM reception will suffer significantly compared with FM. Without the last two, the output sound quality cannot be closely competitive with FM (i.e., 10 kHz full bandwidth on AM vs. 15 kHz nominal for FM).

We therefore petition the FCC to mandate the following minimum allowable performance specifications for all AM receivers that will be manufactured and installed in new automobiles as of January 1, 2016:

Audio Bandwidth: 10 kHz typical, adaptive, with a minimum nominal bandwidth of 7.5 kHz
Signal-to-Noise Ratio: minimum 55 dB, preferably 60 dB
Sensitivity: –120 dBm for a signal-to-noise ratio (SNR) of 10 dB
Selectivity: 25–50 dB (adaptive filtering, using co-, adjacent-, and alternate-channel detection)
Dynamic Range: 100 dB
Noise Figure: 1–3 dB
Image Rejection: –50 dB
Intermod: IP2, IP3 intercepts +10 to +40 dBm
IF: low with image-rejecting down-conversion, or double-conversion
Stereo Separation: minimum 25 dB

We need the full support and backing of you, the AM radio broadcasters, to be able to communicate with Commissioner Pai and Mr. Doyle how imperative it is that these measures be implemented on a fast approval track without further delay in order to put AM radio in a more competitive position with FM radio. … Working together, we can restore AM radio to provide the high-fidelity audio reception that the public listening audience demands.

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