AM Bands Research Articles

Shaping of Radio in Mexico in the Last Decade: 2010-2020

An analysis was made of the Mexican radio industry and the main groups that comprise it, describing the financial information that is available. The essay was elaborated following the deductive method, with a hermeneutic paradigm, according to the experience acquired in the radio industry. A linear regression was estimated from 2005 to 2020, showing a negative relationship of 98.9% between the percentage of households that have radio and those that have internet (the more households that use internet, the lower the proportion that use radio). Advertising in the national radio industry is falling sharply in recent years, in 2016 it absorbed 10.3% of total advertising spending in the country, reaching only 5% in 2020, declining to less than half of the share it had four years earlier. Grupo Radio Centro takes an average 15.4% of advertising from 2016 to 2020, while Televisa Radio takes 12% (before the sale of stations), both corporations take 27.5% in 2018 and 29.6% in 2019, adding six other radio groups (Fórmula, Imagen, Radio Mil, Radiorama, Stereo Rey and ACIR), they would at least have 41.1% of national radio revenues. The most important radio stations in the country have started to broadcast their content through websites, in which they transmit in real time the same programming they broadcast on their AM or FM frequency bands.

The temporal modulation structure of illiterate versus literate adult speech.

The temporal modulation structure of speech plays a key role in neural encoding of the speech signal. Amplitude modulations (AMs, quasi-rhythmic changes in signal energy or intensity) in speech are encoded by neuronal oscillations (rhythmic variations in neural excitability in large cell networks) that oscillate at matching temporal rates. To date, however, all neural studies have investigated adult-directed speech (ADS) as produced and perceived by highly literate adults. Whether temporal features of ADS vary with the skills of the speaker, for example literacy skills, is currently unknown. Here we analyse the temporal structure of ADS spoken by illiterate, low literate (≤ 4 years of literacy) and highly literate (≥ 12 years of literacy) adults. We find that illiterates produce speech differently. Spontaneous conversational speech produced by illiterate adults showed significantly less synchronised coupling between AM bands (less phase synchronisation) than conversational speech produced by low literate and highly literate adults, and contained significantly fewer syllables per second. There was also a significant relationship between years of literacy and the amount of theta-band energy in conversational speech. When asked to produce rhythmic proverbs learned in childhood, all groups could produce speech with similar AM phase synchronisation, suggesting that the differences in spontaneous conversational speech were not caused by physiological constraints. The data suggest that the temporal modulation structure of spoken language changes with the acquisition of cultural skills like literacy that are usually a product of schooling. There is a cultural effect on the temporal modulation structure of spoken language.

Sound system for industrial tool chests

A sound system for industrial tool chests modifies a tool chest with drawers to provide sound and music to technicians at work in a shop. The sound system has a power supply and electronics mounted in the vacant spaces within a tool chest. The power supply has ducting and a fan for cooling. Wiring delivers power from the power supply to the electronics and a player. The electronics include a dropping resistor and illuminated on-off switch. The player can play one or all of AM, FM, and other radio bands, broadcast or cable TV, video and other digital signals, and recorded media of many kinds. The player distributes a signal to two or more speakers mounted to the bottom of the tool chest, and alternatively in the top. The present invention installs within single chests and multiple story chests. Sound from the speakers reflects upon a shop floor to send music throughout the shop.

Electromagnetic interference at the mains ports of an equipment

Distribution line hardware can generate radio- frequency interference (RFI). Such interference can impact the AM and FM bands as well as VHF television broadcasts. The paper presents a reversed electromagnetic interference problem, due to the proximity of two AM radio broadcasting stations which injected especially common mode conducted emissions over the maximal limits specified by the national regulations in the public overhead low voltage mains network. These emissions determined the malfunction of the gas heating centrals Themaclassic Saunier Duval installed in the area. The problem was solved by the retro fitting of an extra EMI filter for the mains network, as presented in the paper.

Mobile Reception of Digital AM Audio and Data Services Using Long-Range Skywave Propagation

Digitization of AM radio systems promises a revival of the currently underutilized broadcasting bands below 30 MHz. Its prospects are near-FM sound quality, automatic tuning, and interference-free reception. Using skywave propagation in some of the bands, a potentially very large area can be covered by a single transmitter if the appropriate frequency and power are chosen. In this paper, we compare mobile and stationary reception at various frequencies, investigate the correlation between solar sunspot activity and reception quality, and analyze how non-audio data service can efficiently be broadcast with digital radio systems in the AM bands. Restrictions regarding the antenna size together with varying ionospheric conditions and and man-made noise make the reception of radio transmissions below 30 MHz in a car a challenging problem. Using the Digital Radio Mondiale (DRM) system, a total of 58 measurements were conducted both in rural and urban environments in fall 2005, most of them in the 49 m, 41 m and 17 m short wave bands, but also in long wave and medium wave bands. A stationary reference receiver recorded data of the same transmission in parallel with the mobile measurements. Comparison of both data sets allowed for a detailed analysis of the impact of mobility on the reception quality. The results show that particularly in rural areas, mobile reception is indeed reliable and perceived as high quality. Only when ionospheric disturbances push signals to just above the required Signal-to-Noise Ratio (SNR), in-car reception fades more frequently than at a stationary receiver. In urban and industrial areas, shadowing effects (tunnels, large buildings) and man-made noise (power lines, etc.) cause even more frequent dropouts. Thus most of the problems known from analog AM reception in cars will remain the same for digital broadcasting. However, where it works, the digital audio quality is clearly superior to that of analog AM. Therefore, we believe that digital radio in the AM bands is a valuable complement to other digital broadcast services, e.g. by augmenting their coverage in rural areas, where network deployments for higher frequencies may economically not be feasible. Further, the data features-although limited-make digital broadcasting in the AM bands an interesting candidate for telematics and traffic information services covering very large areas.

On the Crossed Field Antenna Performance

Lately, short antennas and Crossed Field Antennas (CFA) have attracted broadcast and amateur community attention. The CFA antenna has been developed in the last decade of the 20th century, trying to obtain a compact transmitting antenna for low and medium frequency AM bands. The CFA is intended to be used in order to get a low profile antenna and a supposed performance similar or better compared to a quarter-wave monopole. The CFA has a short monopole and a metallic disk close to the monopole base, both mechanical structures being fed by means of two separated generators. Thus, the CFA has two ports and can be analyzed from the Network Theory point of view. In this paper, the CFA has been studied exhaustively using the Transmission Line Method (TLM) in order to obtain an equivalent network and the antenna performance. Due to the lack of theoretical data to explain the CFA antenna behavior, the TLM has been validated by means of Moment Method simulations and some available experimental data

Wideband receiver for Digital Radio Mondiale

Broadcasting within the traditional AM bands is set to change with the introduction of digital broadcasts. Wideband receiver architectures allow many of the advanced functions of standards such as Digital Radio Mondiale to be implemented and upgraded without changing the hardware. This article describes some of the design issues of wideband receivers and the performance of a practical receiver.

Digital radio takes to the road

While the transition of television to a digital technology with its improved picture and sound quality has been a much publicized and controversial process, radio, has stayed in the background. But in 2001, in the United States, radio broadcasting is making its own digital leap. Two start-ups are introducing a new type of radio broadcast-subscription-based digital audio sent from satellites. With satellite digital audio radio services (SDARS), listeners will be able to tune in to the same radio stations anywhere in the United States. SDARS differs from so-called digital music services, in which direct broadcast satellite or cable system operators provide digitized and compressed audio over their networks, both because of its programming and because SDARS can be received in a moving car, where much of today's radio listening takes place; existing digital audio services cannot. Meanwhile, the free, over-the-air terrestrial broadcasters are expected to choose digital audio broadcasting technologies for both the AM and FM bands by year-end.

On the Power Gained by Clipping Audio and Single Side-Band Speech Signals

Available statistical distributions of instantaneous speech amplitudes have been examined, and an arbitrary but reasonable peak factor has been chosen for a clipping reference level. The power increase in the audio wave (and hence the AM or DSB side bands) due to peak clipping in the audio band has been calculated by using the standard deviation of the clipped and unclipped distributions as a measure of the root-mean-square voltage. A curve will be presented showing the power gain as a function of clipping, and the relation of this to the intelligibility will be pointed out. Statistical distributions of the envelope of a single side-band speech signal have been run and compared with those taken by others, and these have been treated in a manner similar to the audio case to determine the power gained by clipping the single sideband signal. A curve of the power increase under these conditions will also be presented. Unfortunately, there are no data on the intelligibility of clipped single side-band speech to which the computed curve may be related.