Provisions for High Frequency Future Use

An area of widespread interest at the 1979 World Administrative Radio Conference (WARC-79) was concerned with allocation proposals related to the modification of the high-frequency (HF) (4-27.5 MHz) portion of the spectrum. From a wide range of proposals, the Conference adopted allocation provisions that reduced the exclusive fixed-service bands by two-thirds, made significant allocations to the broadcasting and maritime-mobile services, and provided somewhat lesser spectrum provisions for the amateur service. Shared use of fixed bands by the mobile service was greatly increased. Few changes were made to aeronautical service allocations. Provisions were planned to remove an unused fixed-service assignment from the International Telecommunication Union (ITU) Master Frequency Register, and to provide special assistance to Less Developed Countries (LDC's) to enable them to better meet their fixed requirements. A conservative schedule of changes, through 1994, was adopted, including several specialized planning conferences to assist in optimizing the use of HF bands. With continued national needs and improved technology being developed and adopted by the ITU member countries, systems in all authorized HF services will be widely used to meet requirements of the world community for a long time to come.     

准随机跳频信号的二维处理

高频雷达工作的波段十分拥挤,因而可用的连续带宽比较窄,雷达获得距离分辨力极为有限.为避开干扰频段能够提高系统带宽,本文采用了一种频带不连续的准随机跳频信号.并根据信号的特点,系统地提出了该信号的二维信号处理方案.仿真表明,这种方案具有解距离-速度模糊的能力,能有效地抑制最大距离旁瓣,较好地实现了距离速度二维分辨.     

The results of WARC-HFBC (87): technical implications

The planning principles and technical parameters that were decided at the 1987 second session of the World Administrative Radio Conference (WARC) for the planning of the HF bands allocated to the broadcasting service (HFBC) are described. These planning principles and parameters are intended for use in developing test plans to satisfy the world's high-frequency broadcast requirements. Those parameters that were modified at the second session of the conference are discussed toward obtaining a workable and universally acceptable planning system for shortwave broadcasting. With reference to the results of the planning exercises that were used as the basis of decisions at the second session, the likely impact of these decisions on the HF broadcast planning process is described. Some issues that are likely to concern the US broadcasters in preparation for the third session of WARC are summarized in conclusion     

Jamming to the HF broadcasting service

The Institute for Telecommunication Sciences has been actively involved in an internationally coordinated monitoring program to determine the location of emitters of harmful interference (jamming) to the high-frequency (HF) broadcast service. four monitoring programs were undertaken between October 1984 and June 1986. The procedures that have been used and the results that have been obtained are summarized. The locations of the emitters that cause jamming to the HF broadcast service are shown and selected characteristics of the jamming environment are described. The degree to which jamming that is directed to certain broadcasters adversely impacts the performance of other broadcast services that operate on the same or adjacent channels as the targeted broadcaster is examined     

A modified rain attenuation prediction model for tropical V‐band satellite earth link

Radio wave propagation plays a very important part in the design and eventually dictates performance of space communication systems. Over time, the requirements of satellite communication have grown extensively where higher capacity communications systems are needed. Escalating demands of microwave and millimetre wave communications are causing frequency spectrum congestion. Hence, existing and future satellite system operators are planning to employ frequency bands well above 10 GHz. The challenge in operating at such high frequencies for communication purposes is that there exists stronger electromagnetic interaction between the radio signals and atmospheric hydrometeors. Such instances will degrade the performance of such high frequency satellite communication systems. The development of a revised model for a better‐improved rain fade prediction of signal propagations in tropical region is considered very important. Researchers and engineers can employ the model to accurately plan the future high frequencies satellite services. Copyright © 2014 John Wiley & Sons, Ltd.     

非连续谱高频雷达跳频波的信号处理

在高频雷达的工作频段中,电磁环境极其恶劣,一般很难找到一段连续无扰的工作频段,因此需要根据外部频率监测的结果来选取雷达工作的频率点,以提高雷达的有效带宽;但是由于频谱的不连续,传统的处理方式不再适用.作者提出一种新的处理方法,先对回波进行速度谱处理,补偿相应的相位,然后对距离维进行先匹配后用加权迭代的最小二乘滤波器进行滤波.仿真结果表明,该算法不仅能得到目标的二维分辨,而且能极大地抑制距离旁瓣.     

Classification of phasometry techniques for high-frequency bands

The paper has presented a classification of phasometry techniques for high-frequency bands developed by the author. The purpose of the study was substantiated, basic conditions were considered under which the classification was performed, and requirements set for the classification criteria were also substantiated. The attribute of “frequency conversion” was accepted as a general priority criterion for distinguishing the phasometry methods of high-frequency bands from the phasometry techniques of low-frequency bands. The classification of techniques is presented in the form of text and tables. It was performed for the techniques that can be implemented in the simplest way and the majority of which are most often applied in practice. The results have been extended to other techniques and circuits of phase meters for different bands of high frequencies.     

两输入全差分高频宽线性可调的OTA及其滤波器应用

文章提出了一种采用两输入全差分结构、线性可调范围宽的高频跨导运算放大器，适合于需大范围连续调谐的高频连续时间滤波器。仿真结果表明，通过频率补偿，在高频情况下，它不仅具有良好的线性输入和线性可调范围，而且具有较好的频率响应特性，对高频滤波器的性能有一定的改善。     

非连续谱雷达信号设计综述

非连续谱雷达信号是一种特殊的认知雷达信号,其频谱由多个离散的频带组成,且能够随着外界干扰的变化自适应地调整离散频带的分布结构.因此,这种信号适用于干扰密布、频谱拥堵的工作场景.非连续谱信号设计主要研究两个问题:一是如何根据干扰环境选取最优的非连续频谱结构以满足雷达抗干扰和分辨性能要求;二是如何根据最优的非连续频谱求解出...     

Design and performance analysis of an advanced, narrowbandintegrated voice/data mobile radio system

Private land mobile communications have experienced significant demand for increased capacity and for new services, but congestion within the currently allocated 450 and 800 MHz bands has severely limited the capability of present generation systems to meet this demand. This paper proposes a narrowband integrated voice/data mobile radio system which triples current voice traffic capacity and simultaneously provides capacity for mobile data communications such as mobile data terminals, automatic vehicle location, and mobile facsimile by utilizing the silence gaps inherent in speech. The system is designed to fit within the narrowband 25 kHz channels in the 450 and 800 MHz frequency bands, and thus the system can replace existing private land mobile radio systems with minimum impact. The centerpiece of the system design is an evolutionary multiplexing and access control technique known as Packetized Data, Voice Dedicated (PDVD) Burst Switching which allows transmission of data within the silence gaps inherent in speech. Simulation results for various voice and data traffic loads show the flexibility and efficiency of the proposed narrowband integrated voice/data mobile radio system     

高频地波雷达多干扰的极化抑制

天波电台干扰是高频地波雷达所面临的主要干扰,虽然采用频率捷变技术可以躲避干扰,但是当短波电台十分密集时很难找到合适工作频段的,而且当存在与雷达回波同方向入射的干扰时,空间滤波技术也无能为力。利用极化技术可以较好地解决以下问题,但目前高频地波雷达中的极化滤波还只限于对单干扰的抑制,为了进一步拓宽雷达的工作频段,本文研究了多干扰的极化抑制问题,给出了一种在频域同时提取多干扰极化特征的方法,并根据这一方法构造了一种频域极化滤波器,使得频带互不重叠的多个干扰可以被有效滤除,而不受极化度的限制,从而克服了以往极化滤波器只能处理极化度较高的干扰的特点。理论和仿真实验证明了算法的有效性。     

边境地区150 MHz/400 MHz陆地移动业务频率协调方法

对我国与周边国家在150 MHz/400 MHz频段陆地移动业务规划和国际电信联盟申报台站情况进行分析,比较目前现存协调方法,并对划分信道的可行性进行分析,最后给出上述频段的协调建议。     

Fundamental Limits for Radio Signals with Large Bandwidth

Radio services have traditionally used narrow frequency bands individually assigned. More recently, the concept of sharing very wide frequency bands by several users has been advanced, and this opens the door for the use of much larger bandwidths than in the past. This paper investigates the limits imposed by nature on the bandwidth of line-of-sight radio services operating in the earth's atmosphere. Furthermore, it investigates the limits for time resolution of radio signals, as well as the related limit of the angular resolution of a line array of sensors that receive signals with large bandwidth, and compares it with the classical resolution angle that holds for sinusoidal signals with vanishing bandwidth. Finally, an example is given where the concept of a practically finite bandwidth of a signal reaches its limit, and a more rigorous specification of the signal is required.     

A 580-μW 1.8–6 GHz Multiband Switched-Resonator SiGe VCO With 0.3-V Supply Voltage

This letter presents a fully integrated low-power low-voltage multiband switched-resonator differential cross-coupled voltage controlled oscillator (VCO) implemented in 0.18 SiGe-BiCMOS technology. The VCO operates with a supply voltage as low as 0.29 V, owing to the low knee-voltage provided by the technology, and consumes a total power of 580 muW. Utilizing a switched-resonator, the VCO covers a wide switched frequency range of 1.83-2.97 GHz and 4.36-6.17 GHz with measured phase noise of around 112.2 dBc/Hz with 0.29 V supply and 119.7 dBc/Hz with 1 V supply at 1 MHz offset. Since high-frequency bands experience higher phase noise than the low frequency bands, high- short microstrip line inductors have been used for the high-frequency bands. To the best of the authors' knowledge, the reported VCO achieves the widest switched frequency tuning range with lowest core supply voltage.     

Summary of conclusions of the 1992 World Administrative RadioConference

The major decisions made at the conference are briefly described. Additional frequency bands for shortwave (HF) radio broadcasting were agreed upon. Frequency allocations were made to support a number of US proposals, to provide advanced mobile radio services using low Earth orbit satellites. Allocations for land based mobile services adopted at WARC '92, in the range 1700 to 2600 MHz, are meant to foster improved mobile services that can be used worldwide. An allocation was also made to support commercial telephone service between passengers flying on aircraft and individuals on the ground. Allocations were made for sound broadcasting from satellites, as well as for providing a means to accommodate a complementary terrestrial-based digital audio broadcasting service. New frequency allocations to support space activities were agreed upon, and an allocation was made to the fixed satellite service in the band 13.75 to 14.0 GHz     

A traffic control method for service quality assurance in an ATMnetwork

The authors describe an ATM traffic control method to avoid both long-term and short-term congestion. Call admission control and policing based on user-specified traffic parameters have mainly been studied as ways to avoid long-term congestion. However, these control methods are not practical since it is difficult for users to specify accurate values of traffic parameters that include the effects of cell collision controllers and multiplexers in the customer premises network. In order to solve the problem, they propose an intelligent call admission control method. This method consists of a function to determine user's traffic parameters by monitoring the cell traffic flow of each service and a function to statistically predict long-term congestion by using Gaussian and Poisson distributions. They show that congestion can be predicted by deriving the peak, average, and variation. They also describe how to derive traffic parameters and determine their values. To avoid short-term congestion, we propose reactive control, which drops cells with lower cell loss priority when congestion occurs, and we show the buffer construction and buffer control algorithm used to achieve this. Computer simulations prove that their control strategy is effective for cell toss sensitive services such as VBR (variable bit rate) video service     

An 8-GHz f/sub t/ carbon nanotube field-effect transistor for gigahertz range applications

In this letter, the authors report on the high-frequency (HF) performance of self-assembled carbon nanotube field-effect transistors. HF device structures including a large number of single-wall carbon nanotubes have been designed and optimized in order to establish a new state of the art. The device exhibits a current gain (|H/sub 21/|/sup 2/) cutoff frequency (f/sub t/) of 8 GHz and a maximum stable gain value of 10 dB at 1 GHz, after de-embedding the access pads. Considering such results, nanotube-based circuits with gigahertz performance are now conceivable.     

DVB-T BER measurements in the presence of adjacent channel andco-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     

WARC Allocations and Some of their Impacts on Japan and in Asia

This paper describes certain decisions made at the World Administrative Radio Conference (WARC) held in September 1979 which will have great impact on the utilization of radio in Japan and throughout Asia and Oceania. This paper concentrates on the table of frequency allocations adopted at the conference. It also outlines some of the problems expected at the forthcoming WARC for high-frequency broadcasting (WARC-HFBC) and on the space services planning conferences.