A fully portable apparatus for surveillance of electromagnetic broadcast spectrum and measurement of electromagnetic radiation levels
fully portable apparatus for surveillance of electromagnetic broadcast
Research Interests:
ABSTRACT The problem of channel estimation for Orthogonal Frequency Division Multiplexing (OFDM) systems in fast time-varying and frequency selective radio channels has attracted the attention of scientists and receiver manufacturers. The... more
ABSTRACT The problem of channel estimation for Orthogonal Frequency Division Multiplexing (OFDM) systems in fast time-varying and frequency selective radio channels has attracted the attention of scientists and receiver manufacturers. The wireless communication suffers from Additive White Gaussian Noise (AWGN), fading due to the multipath nature of the channel and spectral dispersion caused by the relative movement of the receiver with respect to the transmitter. In this paper a novel channel estimator for the Next Generation Terrestrial Digital Video Broadcasting (DVB-T2) is proposed. It is based on the estimation of the Doppler Shift (DS) from the variations of the envelope of the edge pilots (EP), in order to estimate the time interval where the channel could be considered as flat and then adaptively adjusting a buffer where the scattered pilots (ScP) carried within the received OFDM symbols during this time interval, are stored and averaged. Because the noise is considered AWGN with zero mean, the averaging process discards the noise and by interpolating the pilots an estimation of the channel is obtained.
Research Interests:
Research Interests: Computer Science and IEEE
ABSTRACT Digital broadcasting services require higher prediction accuracy than traditional analogue networks because digital services are planned with tighter margins on the received signal strength and interference. With the rapid... more
ABSTRACT Digital broadcasting services require higher prediction accuracy than traditional analogue networks because digital services are planned with tighter margins on the received signal strength and interference. With the rapid deployment of digital TV, there is an increasing need for accurate point-to-area prediction tools. There are several propagation models for coverage prediction of DVB-T. Some of them are purely empirical models, and others are mixed, empirical-analytical models, based on measurements campaigns and electromagnetic theory. The aim of this paper is to compare precision fieldstrength measurements taken by a Rohde & Schwarz FSH-3 portable spectrum analyzer with simulation results derived from coverage prediction models, like the NTIA-ITS Longley-Rice model, the ITM (Irregular Terrain Model) using the 3-arc-second SRTM (Satellite Radar Topography Mission) data that is available freely.
Research Interests: Computer Science and IEEE
ABSTRACT This paper compares precision field-strength measurements taken by a Rohde & Schwarz FSH-3 portable spectrum analyzer with simulation results derived from the ITM coverage prediction model (Irregular Terrain Model),... more
ABSTRACT This paper compares precision field-strength measurements taken by a Rohde & Schwarz FSH-3 portable spectrum analyzer with simulation results derived from the ITM coverage prediction model (Irregular Terrain Model), also known as NTIA-ITS Longley-Rice model, in conjunction with the 3-arc-second SRTM (Satellite Radar Topography Mission) geographical data, the propagation predictions of ITU-R Recommendation P.1546 and those of the empirical Hata-Davidson model using HAAT. ITU-R P.1546 and Hata-Davidson models exhibit higher errors at longer distances and therefore necessary corrections should be introduced in the models in order to increase propagation prediction accuracy. Especially, measurements results show that ITU-R P.1546, on average, underestimates the field strength at distances longer than 50 km. The Longley-Rice model using the terrain digital elevations is more accurate, as expected, and its results are closer to the measurement data.
Research Interests:
In modern wireless communications there is an increasing need for higher data rates. Modern Digital TV (DTV), like Digital Video Broadcasting Terrestrial (DVB-TIT2), DVB Handheld (DVB-H), Digital Audio Broadcasting (DAB), 4th Generation... more
In modern wireless communications there is an increasing need for higher data rates. Modern Digital TV (DTV), like Digital Video Broadcasting Terrestrial (DVB-TIT2), DVB Handheld (DVB-H), Digital Audio Broadcasting (DAB), 4th Generation (4G) mobile telephony known as Long Term Evolution (L TE) and IEEE 802.11a/b/g/n for wireless LAN (WLAN) are typical applications where high data rates are needed. The adaptation of Orthogonal Division Multiplexing (OFDM), which is a multicarrier modulation, helped to achieve high data rates while the transmission system became more robust against multipath fading, which traditional single carrier systems failed to handle effectively. The OFDM system divides the available bandwidth into a large number of narrow band sub-channels, which have their own respective subcarrier and each one of them can considered as a flat fading channel. In order to have reliable reception of the transmitted data, the knowledge of the channel impulse response is important...
Research Interests:
Research Interests:
With the rapid deployment of digital TV, there is an increasing need for accurate point-to-area prediction tools. There is a great deal of propagation models for coverage prediction of DTV. Some of them are pure empirical models, and... more
With the rapid deployment of digital TV, there is an increasing need for accurate point-to-area prediction tools. There is a great deal of propagation models for coverage prediction of DTV. Some of them are pure empirical models, and others are mixed, empirical-analytical models, based on measurement campaigns and electromagnetic theory. The aim of this paper is to compare accurate measurements taken by a Rohde & Schwarz FSH-3 portable spectrum analyzer and precision antennas (biconical and log-periodic), with simulation results derived from coverage prediction models, like the NTIA-ITS Longley-Rice model, the ITM (Irregular Terrain Model) using the 3-arc-second SRTM (Satellite Radar Topography Mission) data that is available freely, and the newer ITWOM (Irregular Terrain with Obstructions Model) model which combines equations from ITU-R P.1546 model with Beer's law and Snell's law. Furthermore, measurements for analog FM broadcasting are compared to predictions from the abo...
Research Interests:
Accurate geographical coverage predictions maps for FM and TV are needed for channel and frequency allocations and in order to avoid unwanted interferences. The Longley-Rice model has been used for this purpose over the last four decades... more
Accurate geographical coverage predictions maps for FM and TV are needed for channel and frequency allocations and in order to avoid unwanted interferences. The Longley-Rice model has been used for this purpose over the last four decades and still being used almost exclusively by the FCC in the United States. In this work a comparison is presented between the relative accuracy of this model in the VHF-FM and UHF-TV frequency bands. Simulations were made with accurate and up to date input data (antenna height, location, gain, transmit power, etc.) for the FM-TV stations provided by the ERT S.A. public broadcaster in the region of Thessaloniki – Greece. Finally, the calculated – simulated results were confronted to field measurements using a Rohde & Schwarz FSH3 portable spectrum analyzer and high precision calibrated biconical and log-periodic antennas, and the errors between predictions and measurements were statistically analyzed in the two frequency bands. It has been found in thi...
A fully portable electromagnetic radiation level measurement system is used for measuring radiation levels of commercial FM-TV broadcasts in the VHF-UHF range, as well as GSM 900-1800 MHz signals from nearby base stations. The system... more
A fully portable electromagnetic radiation level measurement system is used for measuring radiation levels of commercial FM-TV broadcasts in the VHF-UHF range, as well as GSM 900-1800 MHz signals from nearby base stations. The system consists of a portable battery operated spectrum analyzer and two high precision wideband biconical antennas. The whole system weights less than 3 kg and can be very easily and time-effectively deployed, executing the required measurements in only a few minutes. The precision of the measurement system is thoroughly studied and accurately determined under laboratory conditions. An extensive survey of measurements is under way in the region of central Macedonia, the city of Thessaloniki and its suburbs, including several sensitive areas such as schools, children playgrounds, kindergartens and high radiation regions, including high-power antenna parks.
Research Interests:
Research Interests:
With the rapid deployment of digital TV, there is an increasing need for accurate point-to-area prediction tools. There is a great deal of propagation models for coverage prediction of DTV. Some of them are pure empirical models, and... more
With the rapid deployment of digital TV, there is an increasing need for accurate point-to-area prediction tools. There is a great deal of propagation models for coverage prediction of DTV. Some of them are pure empirical models, and others are mixed, empirical-analytical models, based on measurement campaigns and electromagnetic theory. The aim of this paper is to compare accurate measurements taken by a Rohde & Schwarz FSH-3 portable spectrum analyzer and precision antennas (biconical and log-periodic), with simulation results derived from coverage prediction models, like the NTIA-ITS Longley-Rice model, the ITM (Irregular Terrain Model) using the 3-arc-second SRTM (Satellite Radar Topography Mission) data that is available freely, and the newer ITWOM (Irregular Terrain with Obstructions Model) model which combines equations from ITU-R P.1546 model with Beer's law and Snell's law. Furthermore, measurements for analog FM broadcasting are compared to predictions from the abo...
Accurate geographical coverage predictions maps for FM and TV are needed for channel and frequency allocations and in order to avoid unwanted interferences. The Longley-Rice model has been used for this purpose over the last four decades... more
Accurate geographical coverage predictions maps for FM and TV are needed for channel and frequency allocations and in order to avoid unwanted interferences. The Longley-Rice model has been used for this purpose over the last four decades and still being used almost exclusively by the FCC in the United States. In this work a comparison is presented between the relative accuracy of this model in the VHF-FM and UHF-TV frequency bands. Simulations were made with accurate and up to date input data (antenna height, location, gain, transmit power, etc.) for the FM-TV stations provided by the ERT S.A. public broadcaster in the region of Thessaloniki – Greece. Finally, the calculated – simulated results were confronted to field measurements using a Rohde & Schwarz FSH3 portable spectrum analyzer and high precision calibrated biconical and log-periodic antennas, and the errors between predictions and measurements were statistically analyzed in the two frequency bands. It has been found in thi...
Measurements of UHF-TV band spectra and field-strength levels in the pre-and post-analogue switch-off periods in the cities of Thessaloniki and Skopje clearly demonstrate the much reduced spectrum occupancy, the lower signal levels, and... more
Measurements of UHF-TV band spectra and field-strength levels in the pre-and post-analogue switch-off periods in the cities of Thessaloniki and Skopje clearly demonstrate the much reduced spectrum occupancy, the lower signal levels, and the feasibility of digital dividend allocations to cellular operators in the 800 MHz band, as well as the feasibility of opportunistic secondary spectrum utilization in extensive parts of the spectrum. The risk of LTE-4G interference to TV services and vice-versa is also pointed out and clearly observed from spectrum measurements near a cellular base station.
In modern wireless communications there is an increasing need for higher data rates. Modern Digital TV (DTV), like Digital Video Broadcasting Terrestrial (DVB-T/T2), DVB Handheld (DVB-H), Digital Audio Broadcasting (DAB), 4th Generation... more
In modern wireless communications there is an increasing need for higher data rates. Modern Digital TV (DTV), like Digital Video Broadcasting Terrestrial (DVB-T/T2), DVB Handheld (DVB-H), Digital Audio Broadcasting (DAB), 4th Generation (4G) mobile telephony known as Long Term Evolution (LTE) and IEEE 802.11a/b/g/n for wireless LAN (WLAN) are typical applications where high data rates are needed. The adaptation of Orthogonal Division Multiplexing (OFDM), which is a multicarrier modulation, helped to achieve high data rates while the transmission system became more robust against multipath fading, which traditional single carrier systems failed to handle effectively. The OFDM system divides the available bandwidth into a large number of narrow band sub-channels, which have their own respective subcarrier and each one of them can considered as a flat fading channel. In order to have reliable reception of the transmitted data, the knowledge of the channel impulse response is important....