Television Interference Research Articles

Evaluation of radiated immunity tests using adjusted pulse modulated signals

The main goals of an engineering test are reproducing a real scenario in a controlled environment and monitoring a device under validation when exposed to such condition. In this context, some recent studies have indicated misalignments between the waveforms suggested by the Radiated Immunity standards and the real telecommunication signals. Reproducing an actual signal in an electromagnetic compatibility laboratory might, however, be an expensive task, since it demands more sophisticated hardware. In this study, a simple solution for this problem is proposed based on adjustments applied to the standardised pulse modulated waveform. The objective is to develop an alternative to the traditional procedures, in an attempt to provide the manufacturers a more realistic test environment for their products. Mathematical manipulations indicate that a good agreement between the adjusted waveforms and a digital television signal cannot be simultaneously achieved in both time and frequency domains. Multiple trade-off solutions are then generated and analysed through electromagnetic simulations. Results show that, in the 210-216 MHz frequency range, the pulse modulated signals model the digital television interference capability better than the classical continuous wave does.

Discussion on Active Television Interference Characteristic of UHV AC Transmission Line

High-voltage transmission line corona and sparking will bring television interference (TVI). Study has been seldom executed about active TVI from HV transmission line, and much less research on UHV AC lines. Based on present literatures, this paper brings forward test method of TVI from HV transmission line. Near straight span and tension tower of Chinese UHV AC Pilot Demonstration Project, several tests about TV picture, TVI field strength, the television signal field strength before and after lines energized, has been carried out in good weather. According to observation, interference characteristics to TV picture has been analyzed. Results indicate that, with increasing distance from the outer phase, UHV single circuit TVI field strength in fine weather attenuates negative exponentially. This paper illustrates it is questionable to use CISPR quasi-peak value for assessment of interference on TV picture caused by UHV transmission line corona and sparking noise.

Co-Channel Analog Television Interference in the TDS-OFDM-Based DTTB System: Consequences and Solutions

During digital television (TV) transition, analog signal disturbs digital terrestrial television (DTT) transmission in an area where a simulcast service is available. In the TDS-OFDM- based DTTB system, the receiver is extremely sensitive to the co-channel interference (CCI) introduced by analog TV service. The CCI not only generates strong narrow-band interference in the frequency domain, but also greatly degrades the estimation of time-domain demodulating parameters in TDS-OFDM receiver. In this paper, a method of the time-domain autocorrelation of the received DTT signal is developed to detect the CCI, and it utilizes the line synchronization mechanism of analog TV signals. Also an IIR filter, setting one notch at each carrier of analog TV signal, is designed to reject the CCI in the time domain. From the filtered signal, synchronization errors and channel responses can be estimated by means of conventional algorithms for TDS-OFDM receiver. A DTMB receiver is designed to verify the proposed solutions and its robustness against the CCI is enforced about 20 dB in terms of signal interference ratio (SIR).

アナログ信号処理を用いた電磁パルス到来方向の高精度推定

Partial discharges (PDs), which occur at coupling points of tension insulators or binding spots of insulated wire of distribution lines, might cause television interference or ground fault. A technique for location of the sources of PDs using time differences in arrival of electromagnetic pulses radiated from PDs has been investigated recently, because it is difficult to find the sources by visual inspection from the ground. However, the technique requires a large and expensive apparatus such as digital storage oscilloscope able to record waveforms of the electromagnetic pulses very fast. We investigate a new technique to estimate the direction of arrival (DOA) of the electromagnetic pulses using analogue signal processing. The experimental analogue circuits for measurement of the time (phase) differences are composed of general purpose modules, i.e., amplifiers, filters, local oscillator, dividers, mixers, etc, and the DOA of the electromagnetic pulse is indicated using a circular symbol superimposed onto the photo image taken with a CCD camera. From the results of the experiments on the DOA estimation, it was proved that the new technique is available for high accuracy DOA estimation of the electromagnetic pulses radiated from PDs in air.

Comparison of Electrical-Environment Characteristics Between Two Different Types of EHV Transmission Lines

This paper represents the analysis results by comparison of characteristics on electrical environment between different EHV transmission lines, such as AN (Audible Noise), RI (Radio Interference), TVI (Television Interference), EMF (Electric and Magnetic Field). In Korea, the transmission lines with nominal voltage of 765-kV have been operating since 2002, and Hungary energized a 750-kV line in 1978. However both EHV transmission lines have different line configuration, Korea is a prime example of the first double circuit 765-kV line in the world, and Hungary has been operating one of the single circuit 750-kV.

DVB-T BER measurements in the presence of adjacent channel and co-channel analogue television interference

This paper presents some laboratory tests carried out to measure the BER degradation caused by an analogue PAL-G television interference on a COFDM 8 K digital television signal. The tests made include co-channel and both upper and lower adjacent channel interference situations. Previously, the ITU-R has presented some protection ratios to be sought when planning DVB-T networks. The results of the work presented here include a wider range of power ratios and their effect on the BER rather than the limit protection values. The new digital services will share the same frequency bands as the conventional analogue television so the exact characterization of mutual interference is a major concern of broadcasters during the transition period when both systems have to co-exist.

Electromagnetic interference from a three phase double circuit 765-kV test line

This paper presents the results of long-term electromagnetic interference (EMI) measurements on the bundle of 6 Cardinal conductors tested at Korea's Kochang 765-kV full-scale test line. The instrumentation and the most important features of the facilities are also described. This new 3-phase double circuit test line can be energized at line-to-line voltages up to 850 kV. The analysis of the data shows that the 6-Cardinal conductor bundle meets the radio and television interference guidelines of the Korea Electric Power Corporation (KEPCO).

Partial discharge XX. Partial discharges in air. II. Selection of line conductors

Corona from overhead transmission lines causes radio interference, television interference, audible noise, and power loss. Overhead lines are designed to limit such corona-induced effects, which are a strong function of weather conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Measurement of the electromagnetic environment of HVDC converter stations

The results of an experimental study on the electromagnetic environment of HVDC (high-voltage direct-current) converter stations are presented. Transient EMI (electromagnetic interference) as well as steady-state RI (radio interference) and TVI (television interference) measurements were made at the Arnott station of BC Hydro and the Chateaguay station of Hydro-Quebec. The maximum values of the electric and magnetic fields measured inside the valve halls of Arnott station are 1.8 kV/m and 3.2 A/m; outside, they are 0.28 kV/m and 0.4 A/m respectively. These values cover the range of normal operation, including start-up and stopping of the converter station. During normal operation of the Chateauguay station, maximum electric and magnetic fields of 0.7 kV/m and 1.1 A/m are measured inside the valve hall; outside, they are below the sensitivity of the measuring system. It is recommended that immunity testing be carried out on electronic equipment to be used either inside or outside the valve halls of converter stations at transient electric and magnetic field levels of 5 kV/m and 10 A/m, respectively, with approximately 1 mu s risetime and 10 mu s duration.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

RFI Source-Locating on Power Lines-An Update

The author describes a practical and efficient means for locating RI (radio interference) and TVI (television interference) sources on power lines, particularly those operating below 70 kV, where most complaints originate. The main emphasis is on locating sparking sources on overhead lines, but the location of RFI sources occurring in underground lines and the location of nonspeaking power line sources are also treated. Particular attention is given to the use of a vehicular locating set (VLS) and its auxiliary equipment. The VLS, with its oscilloscope presentation, tells the investigator if there is a single source of many sources, and makes it possible to handle these one at a time, and to get within one or two poles of a source. It is also shown that a hot-stick sniffer with a dual VHF/ultrasonic function is effective in rapidly pinpointing RFI sources on low-voltage transmission lines. >

RFI source-locating on power lines-an update

The author describes a practical and efficient means for locating RI (radio interference) and TVI (television interference) sources on power lines, particularly those operating below 70 kV, where most complaints originate. The main emphasis is on locating sparking sources on overhead lines, but the location of RFI sources occurring in underground lines and the location of nonspeaking power line sources are also treated. Particular attention is given to the use of a vehicular locating set (VLS) and its auxiliary equipment. The VLS, with its oscilloscope presentation, tells the investigator if there is a single source of many sources, and makes it possible to handle these one at a time, and to get within one or two poles of a source. It is also shown that a hot-stick sniffer with a dual VHF/ultrasonic function is effective in rapidly pinpointing RFI sources on low-voltage transmission lines.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Measurement of the Electromagnetic Environment of HVDC Converter Stations

The results of an experimental study on the electromagnetic environment of HVDC (high-voltage direct-current) converter stations are presented. Transient EMI (electromagnetic interference) as well as steady-state RI (radio interference) and TVI (television interference) measurements were made at the Arnott station of BC Hydro and the Chateaguay station of Hydro-Quebec. The maximum values of the electric and magnetic fields measured inside the valve halls of Arnott station are 1.8 kV/m and 3.2 A/m; outside, they are 0.28 kV/m and 0.4 A/m respectively. These values cover the range of normal operation, including start-up and stopping of the converter station. During normal operation of the Chateauguay station, maximum electric and magnetic fields of 0.7 kV/m and 1.1 A/m are measured inside the valve hall; outside, they are below the sensitivity of the measuring system. It is recommended that immunity testing be carried out on electronic equipment to be used either inside or outside the valve halls of converter stations at transient electric and magnetic field levels of 5 kV/m and 10 A/m, respectively, with approximately 1 mu s risetime and 10 mu s duration. >

RI, TVI and AN characteristics of HVDC insulator assemblies under contaminated condition

The results of investigations into radio interference, television interference and audible noise characteristics of full-scale insulator assemblies for DC+or-600 kV HVDC transmission lines under contaminated and wet conditions are discussed. The interference levels during partial discharges were measured and found to be nearly the same as those as those of existing AC 500 kV transmission lines. Emphasis was placed on the characteristics of partial flashovers known as specific sparkovers under DC voltage on one or a few units in a string. The interference levels during partial flashovers were much higher than those during partial discharges. An insulator with a high flashover voltage, such as one having a diameter of 460 mm, was effective in preventing partial flashovers, at least up to a voltage of +or-650 kV. >

Effect of High Altitude on High Voltage AC Transmission Line Corona Phenomena

This paper summarizes the results of a research effort conducted by Bonneville Power Administration (BPA) to determine the effect of altitude on corona phenomena from high voltage transmission lines. A computer-controlled, reliable, unattended test station was installed at an altitude of 1935 m on a double-circuit 500-kV line near Basin, Montana, to continuously monitor audible noise (AN), radio noise (RI), and television interference (TVI). To obtain comparative data at a lower elevation, another test station was installed on a 500-kV line of similar design near Stayton, Oregon, at an altitude of 277 m. Comparison of the high altitude data with the lower elevation data and with predictions demonstrated that the correction factor of 1 dB/300 m developed in the 1950's and 1960's for radio noise is still valid and is also applicable for AN, TVI and, possibly, corona losses.

UHF television interference associated with cellular mobile telephone systems

An investigation is made into two types of interference which may occur between UHF television and 850 MHz cellular mobile telephone systems: 1) ITV--interference to the cellular mobile telephone receivers, created by a UHF TV transmitter; 2) TVI--interference to the UHF TV receiver, created by the cellular system mobile transmitters. In the case of ITV it has been determined that TV transmitters operating on TV channels 65 through 69 may produce third-order intermodulation, within a radius of about 0.5 mi, to certain telephone channels assigned to mobiles operating in a cellular system fringe area. A judicious choice of telephone channel assignments would mitigate this type of degradation. Alternatively, in the case of TVI, it is shown that within a minimum grade B television service area, it is possible for cellular mobile telephones to at times produce image interference to present-day UHF TV receivers tuned to channels 58 through 61. However, because of cellular telephone subscriber density and channel position (and loading) the probability of interference is expected to be low. An increase of TV receiver image rejection by 20 dB would essentially eliminate all likelihood of this interference.

Television Interference Due to Electromagnetic Scattering by the MOD-2 Wind Turbine Generators

Television Interference Due to Electromagnetic Scattering by the MOD-2 Wind Turbine Generators

Television Interference due to Electromagnetic Scattering by the MOD-2 Wind Turbine Generators

The characterization and identification of electromagnetic interference created by the slowly rotating blade of a MOD-2 wind turbine generator (WTG) is investigated. Field measurement data supports the thesis that at ground level the near field scattered component is an amplitude modulated secondary signal. A prediction methodology to define zones of interference to television broadcast reception is presented.

Environmental aspects of large-scale wind-power systems in the UK

Environmental issues relating to the introduction of large, MW-scale wind turbines at land-based sites in the UK are discussed. Areas of interest include noise, television interference, hazards to bird life and visual effects. A number of areas of uncertainty are identified, but enought is known from experience elsewhere in the world to enable the first UK machines to be introduced in a safe and environementally acceptable manner. Research currently under way will serve to establish siting criteria more clearly, and could significantly increase the potential wind-energy resource. Certain studies of the comparative risk of energy systems are shown to be overpessimistic for UK wind turbines.

A Laboratory Study on RI, TVI and an of Insulator Strings for DC Transmission line Under Contaminated Condition

This paper reports the results of a laboratory study on radio interference (RI), television interference (TVI) and audible noise (AN) of contaminated insulator strings for DC transmission line. It is clarified that RIV (Radio Influence Voltage), TVI and AN levels of contaminated insulator under DC voltage condition are almost the same as those under AC voltage condition, although those of clean insulator and conductor are lower under DC voltage condition than those under AC voltage condition. So, in the DC transmission line, the noises from insulator, especially under contaminated condition, are considered more influential than those in the AC transmission line.

Community Response to Noise from a General Aviation Airport

The paper provides relationships between noise level and response variables through an analysis of social survey and physical data collected around a small general aviation airport. The responses investigated included annoyance, activity interference, health effects, and non-noise effects of general aviation traffic, such as fear of crashes, air pollution, aircraft lights, house vibration, and television interference. Results indicate a much higher response than that predicted by Schultz (1978), e.g., at 30 NEF, Schultz predicts approximately 15% highly annoyed, compared with 28% in this study.