Carl G. Eilers

Digital television transmission parameters-analysis and discussion

Terrestrial digital (DTV) broadcasting is now underway in the major markets in the United States after the Federal Communications Commission (FCC) in several Reports and Orders set the standard on December 24, 1996, and subsequently released rules of operation and broadcaster channel allocations. Broadcasters are concerned with many in-band and out-of-band transmission parameters, including data signal quality, clock tolerance, radiated power tolerance, carrier phase noise, adjacent channel emissions, and precision frequency offset requirements. The FCC permits DTV power-level changes and/or transmitting antenna location and height and beam tilt in the context of the minimum interference levels. The Advanced Television Systems Committee (ATSC) has provided guidelines for broadcasters in the form of suggested compliance specifications, which are covered in this paper.

TV Multichannel Sound - The BTSC System

In late 1978, the Broadcast Television System Committee of the Electronic Industries Association, on behalf of the television industry, formed a subcommittee for the purpose of formulating standards for the broadcasting and reception of multichannel television sound which was to include stereophonic as well as second program (second language, for example) enhancements of the main audio program. On December 22, 1983, the industry chose the Zenith transmission system coupled with the dbx noise reduction system and submitted the combined system, the BTSC system, to the Federal Communications Commission on January 30, 1984. On April 23, 1984, the FCC released a Report and Order in Docket No. 21323 wherein the choice of technical standards was left to the marketplace, but protection was afforded to the pilot frequency of the BTSC system. In addition, if a pilot is transmitted at 15.734 kHz, the BTSC system must be employed as described in the FCC office of Science and Technology Bulletin No. 60.

An analysis of DTV propagation into and within a room in a domestic environment

A window in a room within a domestic environment in a structure with aluminum siding is analyzed with respect to its radiating properties. The window is modeled as a rectangular aperture, which diffracts the distant horizontally polarized signal from a DTV transmitting antenna into the environment of the room. The diffraction signal, also horizontally-polarized, is combined with the distant signal, which penetrates the aluminum siding at some loss, and thereby a field distribution within the room is created. The window-diffracted signal is almost entirely a near field (Fresnel zone) within the room while the distant field is a far field (Fraunhofer zone) within the room. Various locations within the room are examined with respect to echoes, with and without scattering (human) bodies. A receiving antenna is positioned at the locations examined.

The development of a high definition television (HDTV) terrestrial broadcasting emission mask

This paper analyzes the case of HDTV channels, upper and lower, first adjacent to an existing NTSC station assignment and considers the interference from an HDTV adjacent channel, spillover spectra as undesirable co-channel interference into the NTSC channel. A subjective weighting function is developed for random noise interference to NTSC images at the video baseband level. A filter function representing the human visual system at specified viewing distances as a function of image height is developed, first for monochrome, and then extended to color images. The baseband subjective weighting function is modified to include the process of television carrier modulation and demodulation. This carrier modified weighting function is then used to evaluate typical spillover spectra created by high power amplifiers when driven by a modulated digital HDTV signal. BTSC stereo audio (with SAP) is also included in the interference evaluation. Spectral out-of-band spillover limits are established based on the threshold of visibility of the interference as a function of the mileage separation between adjacent channel NTSC and HDTV stations. A high power bandpass filter and band elimination notches are included in the analysis. The results are then applied to two methods of determining spectral emission compliance : measurement of the out-of-band interference spectra with a weighting function, or alternatively, the use of an emission mask.

Analyzing the FCC's DTV spectral emission mask and potential degradation to adjacent channels due to antenna pattern differences

The FCC DTV spectral emission mask is analyzed with an NTSC subjective noise weighting function to determine the desired NTSC to undesired adjacent channel DTV signal ratio at the threshold of visibility of interference. Factors which alter the NTSC/DTV adjacent channel signal ratio at various receiving locations within the NTSC service are examined: (1) the azimuth patterns of the NTSC and DTV broadcast antennas; (2) the elevation patterns of the NTSC and DTV broadcast antennas; and (3) the centers of radiation of the NTSC and DTV broadcast antennas. These factors together with the NTSC/DTV authorized power ratio may make the DTV spillover spectrum exceed acceptable picture (and sound) interference levels even though compliance with the FCC DTV spectral emission mask is met. Spectral shaping solutions are examined by use of the NTSC subjective noise weighting.

Intercarrier Buss Phenomena Analysis and Cures

This partly tutorial paper defines buzz as the result of video related incidental phase modulation (IPM) of the intercarrier. The main sources of IPM are 1. parametric and transit time effects, both non-linear in character and 2. AM to PM conversion of a strictly linear character. 1. is the main source of transmitter visual IPM but can also take place in the receiver. Linear AM to PM is prominent in the receiver as Nyquist IPM.

Television Multichan Nel Sound Broadcasting-A Proposal

hInterest in the addition of stereophonic sound to television broadcasts goes back several decades. It was felt by some that the enhancements of black-and-white images by color in the early 1950s should naturally be followed by an enhancement of the sound as had been the development in the motion picture industry. Broadcasting became the focal point of interest after the introduction of the 45/45 LP stereophonic disc in the mid 1950s. As the decade of the 1950s came to a close, the industry organized the National Radio Stereo Committee (NSRC) which was to determine the feasibility of stereophonic transmission for AM Broadcasting, FM Broadcasting, and TV Broadcasting. After an initial flurry of proposals, it soon became apparent that most of the interest was in FM because it was considered the primary high fidelity medium. AM and TV were set aside and the subsequent effort was solely on FM which resulted in the adoption of standards by the Federal Communications Commission for the FM Broadcast Service on April 19, 1961. The standards were based on NSRC systems 4-4a, the Zenith-GE system.

Echo analysis of side-mounted DTV broadcast antenna azimuth patterns

Azimuth pattern analysis of a side-mounted antenna is made keeping reflections separate from the main radiated signal. Each reflection is characterized by a reflection coefficient and path difference in wavelengths at a distant receiving summing point. At each azimuth, the reflections are expressed as echoes accompanying a modulated VSB data pulse. The corresponding receiver equalizer tap weights are determined from which the DTV receiver threshold impact is calculated. Measurements of a side-mounted antenna using an azimuth fly-around technique are compared to the calculated results for specific azimuth directions. It is concluded that the DTV performance degradation caused by close-in reflections from adjacent tower members may be predicted by calculation and that the degradation is small.

Spectrum compatible high definition television

The spectrum compatible high definition television (SC-HDTV) system achieves the encoding of a 28.9 MHz source signal for transmission over a 6 MHz channel in the terrestrial TV broadcasting bands. The signal format reduces mutual interference between existing NTSC broadcasts and the high definition broadcasts, and therefore significant amounts of currently unused spectrum space can be used for simulcasting SC-HDTV. A concise description of the system is followed by a discussion of aspects of special interest to the terrestrial broadcaster. >

The BTSC multi-channel television sound system

Description, specifications du systeme et comparaison avec la radiodiffusion stereophonique en modulation de frequence