Showing papers on "L band published in 1999"
TL;DR: A statistical model predicts the worst case radiometric sensitivity for a 1.4 GHz digital receiver and theoretical results show that only 2-3 bits of converter resolution are needed to approach the performance of an ideal analog radiometer.
Abstract: This paper presents a novel direct RF sampling receiver architecture that will greatly facilitate the implementation of higher spatial resolution satellite radiometers for improved near-term climate forecasting. Direct-sampling is especially suitable for integration onto the distributed, multiple element platform used in L-band synthetic thinned array radiometry (STAR). To evaluate the direct-sampling concept, the authors have developed a statistical model that predicts the worst case radiometric sensitivity for a 1.4 GHz digital receiver. Theoretical results show that only 2-3 bits of converter resolution are needed to approach the performance of an ideal analog radiometer and that sampling jitter will not significantly degrade the performance of STAR.
45 citations
18 Feb 1999
TL;DR: In this paper, the authors demonstrated the first UBWDM transmission over a dispersion shifted fiber utilizing the 1470-nm band, the 1550-nm and the 1590-nm bands.
Abstract: Ultrawide-band wavelength-division multiplexing transmission over a dispersion shifted fiber utilizing the 1470-nm band, the 1550-nm band, and the 1590-nm band is demonstrated for the first time to our knowledge.
41 citations
TL;DR: General investigations and results from ratherextensive measurement campaigns are presented tocharacterize the propagation channel of SatellitePersonal Communication Systems and a new conceptual partitioning of the full link is introduced.
Abstract: General investigations and results from ratherextensive measurement campaigns are presented tocharacterize the propagation channel of SatellitePersonal Communication Systems; in the measurements the satellite was simulated by a helicopter andmeasurements at S band and L band were made. A newconceptual partitioning of the full link is introduced;the measrement equipment and the environment aredescribed. The major part of the paper deals withpresentation of the measurement results and theiranalyses. Measured and analyzed are average lossincluding satellite elevation and azimuth positiondependence, first-order statistics, Doppler characteristics, andwide-band characteristics. Finally, some rather generalconclusions are drawn.
18 citations
TL;DR: In this article, the characteristics of random ionospheric inhomogeneities are described including their dependency on the geophysical parameters and used in a propagation model to estimate the propagation errors and the fades of the transmitted signals.
Abstract: The characteristics of random ionospheric inhomogeneities are described including their dependency on the geophysical parameters. They are used in a propagation model to estimate the propagation errors and the fades of the transmitted signals. Margins to be included in a budget link are subsequently determined. Features of our propagation model are presented with typical results for VHF and L band links.
14 citations
TL;DR: In this article, a low-cost L-band hybrid-coupled 90° phase shifter using a compact branch line coupler to minimize its size and employing low cost UHF band p-i-n switching diodes was presented.
Abstract: The design, development, and testing of a low-cost L-band hybrid-coupled 90° phase shifter are presented. The developed phase shifter uses a compact branch line coupler to minimize its size, and employs low-cost UHF band p-i-n switching diodes to minimize its production cost. The diodes in a stand-alone configuration feature large stray capacitance, which make them a poor-quality open circuit in the reverse-bias state. An LC compensation technique is applied to tune out this capacitance and make the diodes applicable to L-band. The developed phase shifter exhibits less than 1.0 dB insertion loss, more than 15 dB RL, and ±8° phase deviation over 225 MHz centered at 1.6 GHz.
9 citations
18 May 1999
6 citations
TL;DR: A study is presented of the amplitude and multipath phase variations found in the land mobile satellite channel at L-band (1.820 GHz) in urban areas and the received time-series are split into three categories or "states" according to the degree of shadowing experienced: line-of-sight, light shadow, and deep shadow.
Abstract: A study is presented of the amplitude and multipath phase variations found in the land mobile satellite channel at L-band (1.820 GHz) in urban areas. The received time-series are split into three categories or "states" according to the degree of shadowing experienced: line-of-sight, light shadow, and deep shadow. Statistical models and their corresponding parameters (extracted from experimental data) are provided for a wide range of elevation angles (10/spl deg/-70/spl deg/) both for the amplitude and for the phase variations due to multipath.
5 citations
Patent•
07 Jul 1999TL;DR: In this article, a wide band amplification can be obtained by adopting the 1st and 2nd optical amplifiers 14, 16 and the constitution can be simplified by using the control unit for both the first and the second optical amplifier 14 and 16 in parallel.
Abstract: PROBLEM TO BE SOLVED: To obtain an optical amplifier having a wide band and simple constitution in a system having the optical amplifier. SOLUTION: The optical amplifier is provided with a 1st optical amplifier 14 for a 1st band (e.g. a conventional band: C band), a 2nd optical amplifier 16 for a 2nd band (e.g. a long wavelength band: L band), an optical demultiplexer 20 and an optical multiplexer 24 for connecting the 1st and 2nd optical amplifiers 14, 16 in parallel, and a control unit for controlling the 1st and 2nd optical amplifiers 14, 16 so as to keep optical power on an output port constant. In the constitution, a wide band amplification can be obtained by adopting the 1st and 2nd optical amplifiers 14, 16 and the constitution can be simplified by using the control unit for both the 1st and 2nd optical amplifiers 14, 16.
4 citations
Patent•
NEC1
TL;DR: In this paper, a DME/TACAN was used for the aircraft band and a GPS reinforcing data was overlapped onto distance information to be broadcast, and the function of broadcasting a data by overlapping the data onto the distance information of the DME was achieved.
Abstract: Frequency resources of a DME/TACAN band specified for the aircraft band are effectively utilized, and a GPS reinforcing data is overlapped onto distance information to be broadcast. A header is added to a DGPS reinforcing data, and the transmitting pulse level of a conventional ground DME system is modulated, and the data is broadcast to an airborne system. In the airborne system, a threshold value of “1” and “0” is generated by a level detecting device ( 5 ), and the start point of the data is detected by a header detecting device ( 6 ), and the reinforcing data is supplied to the airborne system. Consequently, the function of broadcasting a data by overlapping the data onto the distance information of the DME is achieved. Since the DME uses the L band, the radio interference with the existing ILS, VOR, aircraft radio transmission, and broadcasting station can be avoided.
3 citations
21 Feb 1999
TL;DR: In this article, the authors present the first demonstration of an 80nm wavelength shift by four-wave mixing from the C-band to the L-band, where the power penalty at 10/sup -9/BER for a 2.5 Gb/s signal is less than 1.0 dB.
Abstract: We present the first demonstration of an 80-nm wavelength shift by four-wave mixing from the C-band to the L-band. The power penalty at 10/sup -9/ BER for a 2.5 Gb/s signal is less than 1.0 dB.
3 citations
20 Apr 1999
TL;DR: In this article, the authors describe a L band solid state pulsed transmitter which has been developed to equip a new mode S station for air traffic control in the frame of the program POEMS (Pre-Operational European Mode S Station).
Abstract: This paper describes a L band solid state pulsed transmitter which has been developed to equip a new mode S station for air traffic control in the frame of the programme POEMS (Pre-Operational European Mode S Station). The STX2000 transmitter was designed with the new available technologies to meet the mode S requirements defined by the International Civil Aviation Organisation (ICAO) but it is also compatible with the present air traffic communication system. Compared to the old generation, it typically delivers more power (3 kW peak at 1030 MHz) to a 2 channel rotating antenna: sum channel (directional propagation) and control channel (omnidirectional propagation) with the capability of a dynamic output power attenuation (0 dB to 12 dB) in order to modify the radar range according to the aircraft position. The maximum 2400 mode S interrogations per second can be transmitted on the sum channel with a duty cycle which can reach 64% during 4.8 ms (96 consecutive made S interrogations). Regarding the air traffic control application, a precise safety analysis defined tests that have to be run in operation to report any failure which may affect the system performance and to protect the transmitter itself (for instance, output RF transistor junction temperature measurements).
28 Jun 1999
TL;DR: The results of a benchmark case study suggest that, with DSDR configured in a total power mode, a sensitivity of 0.2 K is attainable for Earth remote sensing applications like soil moisture retrieval.
Abstract: This paper examines the noise characteristics of a direct RF sampling receiver whose architecture is suitable for high resolution aperture synthesis radiometry. The authrs have designed a 1.4 GHz direct-sampling digital radiometer (DSDR) to verify the discrete-time statistical model of the receiver and to evaluate current analog-to-digital converter technology. Several tests characterize the dynamic range and noise-equivalent sensitivity (NE/spl Delta/T) caused by quantization, finite data sampling, and variations in signal bias. The results of a benchmark case study suggest that, with DSDR configured in a total power mode, a sensitivity of 0.2 K is attainable for Earth remote sensing applications like soil moisture retrieval.
Patent•
11 May 1999
TL;DR: A terresterial communication system, including at least one LTS, preferably located in a mast structure or any other supporting structures, has every LTS a high-frequency communication equipment in response to the conventional synchronous satellite for digital transmission of video signals, audio frequencies or data for emission at a low output or a higher frequency than others in the L band (1-2 GHz), S band (2-4GMz), and having a better full-direction antenna for horizontal emission.
Abstract: A terresterial communication system, including at least one LTS, preferably located in a mast structure or any other supporting structures, having every LTS a high-frequency communication equipment in response to the conventional synchronous satellite for digital transmission of video signals, audio frequencies or data for emission at a low output or a higher frequency than others in the L band (1-2 GHz), S band (2-4GMz), and having a better full-direction antenna for horizontal emission.
Patent•
22 Sep 1999
TL;DR: In this paper, the authors present a terrestrial communication system, which facilitates audio, video, data and any other type of communication within a local geographical area, and with an extremely large number of communication channels being made available simultaneously at a very low cost.
Abstract: A terrestrial communication system, facilitating audio, video, data and any other type of communication within a local geographical area, and with an extremely large number of communication channels being made available simultaneously at a very low cost. It comprises at least one local terrestrial satellite (LTS), preferably located in a mast or any other supporting structure, each (LTS) having high frequency communication equipment substantially corresponding to a conventional geostationary satellite for digital transmission of video, audio or data, arranged to transmit in the L Band (1-2 GHz), the S Band (2-4 GHz) or a higher frequency band with a relatively low power output and having a preferably omnidirectional antenna installation for transmission in a substantially horizontal plane. The signals can be digitalized according to MPEG-2 or according to any known or future signal algorithm.