The Influence of Finite Bandwidth on the Capture Effect in FM Demodulators

In this paper a formula is derived for the capture ratio of an FM demodulator of which the finite bandwidth has been taken into account. The results obtained in a numerical example are in complete agreement with the measurements made on a physical detector.     

FM广播接收机辐射骚扰的抑制

指出FM广播接收机在出口认证中,EMC测试不合格项出现机率最多的是辐射骚扰超出标准限值.可以在本振谐振回路向IC内部本地振荡器信号注入端口串连接入一只阻值合适的电阻,用降低本振振荡强度的办法,成功解决了辐射骚扰超出标准限值的问题,使在测装置顺利通过EMC测试,此方法既方便又经济.     

Automatic Cancellation Method of Multipath Echo Distortion in FM Broadcasting Receivers

An automatic canceling method of multipath echo distortion in FM broadcasting receiver is proposed. The cancelling system is composed of two additional parts to the conventional receiver: a programable transversal filter operating at linear IF stage and a microcomputer. The microcomputer calculates echo parameters (relative echo amplitudes, delay times and phase differences between direct wave and echoes at the carrier frequency), from the amplitude-frequency characteristics between sending station and IF stage of the receiver, which is obtained from both outputs of an IF signal envelope detector and FM demodulator. The microcomputer sends control signals to the weighting circuits of the transversal filter. The output signal of the transversal filter is fed back and added to the incoming signal. Tap weighting adjustment is continued until a flat amplitude-frequency characteristics is obtained. The results of computer simulation show this method works well for various echo conditions and the distortion can be completely eliminated.     

Maximum A Posteriori Estimator for Suppression of Interchannel Interference in FM Receivers

In this paper an FM detector capable of suppressing the degradation in receiver performance due to the presence of an interfering signal is presented. Optimum receiver structures based on maximum-aposteriori estimation procedures are first derived and then a practical demodulator based on the optimum receivers is examined. The receiver consists of two phase-locked loops (PLL) interconnected in a manner to permit one PLL to lock onto and track the Stronger received FM signal while the other loop tracks the weaker of the two received FM signals. The detector has the capability of demodulating both the desired received FM as well as the interferer even for the case when both signals are co-channel. Experimental results demonstrating such capability even in the presence of strong input Gaussian noise are presented.     

Compatibility of Spread-Spectrum Signals with Narrow-Band FM Receivers in VHF Mobile Networks

The feasibility of a tentative introduction of the spread- spectrum (SS) scheme in VHF mobile bands on an area-and frequency-sharing basis with existing FDM service is investigated. It is shown that compatibility can be attained only for cellular SS networks with small cell area. The approach outlined may be useful in the treatment of general compatibility problems involving variable geometry of the transmitter/receiver configuration.     

调频锁相环路中分频器对调频的影响

本文详细分析了调频锁相环路中分频器的作用,给出了选择分频比的依据。     

New Adaptive All-pass Based Notch Filter for Narrowband/FM Anti-jamming GPS Receivers

The global positioning system (GPS), which provides accurate positioning and timing information, has become a commonly used navigation instrument for many applications. The application of a new adaptive all-pass based notch filter (ANFA) for narrowband/FM interference suppression and frequency estimation in GPS receivers is proposed. An ANFA structure that achieves better unbiased characteristics with its coefficients is employed to accurately estimate the narrowband interfering signals in online fashion. A variable convergence factor that optimizes the maximal mean square error (MSE) reduction in each iteration is applied in a modified adaptive Gaussian–Newton (MAGN) algorithm. The proposed MAGN algorithm can lead to both faster convergence speed and higher estimation accuracy. Simulation results show that the ANFA offers a better performance than conventional linear predictors in terms of the SNR improvement and the mean output power (MOP) under the interference environments of interest.     

Radiation Measurement on FM Receivers; Conversion Factors Between IEC and IRE Methods on a Statistical Basis

Since the establishment of the method for the measurement of radiation from FM and TV receivers, by Subcommittee 12-A of the International Electrotechnical Commission (IEC), the problem of establishing the conversion factor between the IEC method and the IRE method has aroused great interest. Because of the irregular radiation patterns of the receivers, the conversion factor may be determined preferably on a statistical rather than a theoretical basis. Here the procedure is described by which the radiation measurements were carried out on 74 FM receivers, using both methods, and the site calibrations were made. The results are analyzed and the basic concept of correlation factor introduced, in order to convert the limits of one method to the limits of the other.     

WCDMA接收系统中邻通道干扰研究

本文对3G的WCDMA中的ACS参数进行分析,解释33 dB的理由。并对实际电路的RF接收的ACS指标进行测试,设置测试的中心频率是2 110 MHz、2 140 MHz和2 170 MHz 3个高中低频率点,测得在偏离中心频率点 /-5 MHz的调制干扰信号值为-48 dBm到-42 dBm之间(BER=0.001时),可得幅度裕量在3.9 dB到9.2 dB之间,满足3GPP中的干扰信号-52 dBm电平要求。     

噪声调频干扰对ISAR的压制效果分析

逆合成孔径雷达(ISAR)在军事领域的应用越来越广泛,研究对其有效的干扰方法非常必要。文中结合目前ISAR及干扰机典型参数对ISAR的压制干扰进行了理论分析;基于实测数据对工作在瞄准、阻塞和扫频方式下的噪声调频干扰进行了仿真,比较分析了干扰效果;讨论了瞄频误差、干扰带宽对干扰效果的影响。理论与仿真实验表明,虽然ISAR具有很高的成像处理增益,但由于要经过复杂的运动补偿,噪声压制干扰在一定条件下可以达到较好的效果。     

Low-Noise Millimeter-Wave Receivers

Over the past several years, significant improvements have been made in solid-state devices (that is, avalanche diodes, Gunn diodes, varactors, mixer diodes, etc.) that have enhanced the overall capability and low-noise performance of millimeter-wave receivers. With these improved devices, it is now possible to configure completely solid-state low-noise millimeter-wave receivers. As is similar in the microwave region, low-noise parametric amplifiers, broad-band low-conversion-loss mixers, and solid-state local oscillators are now available. Furthermore, cryogenically cooled parametric amplifiers and mixers are also being developed that will result in achieving the ultimate in system sensitivity. With the flexibility offered by these completely solid-state millimeter-wave components, it is now possible to design the optimum system configuration for the intended application whether it be an advanced communication system, a sophisticated EW application, a RADAR system, a radiometric system, or satisfying any of the numerous receiver requirements that are being evolved. This paper explores the trends that are being developed in the millimeter-wave region and their application to system design. The performance criterion of various receiver systems and their sensitivity requirements are presented. A review of the system operating noise temperature concept and the method by which it can be determined and its applicability to low-noise components is demonstrated. A review of the state-of-the-art of low-noise systems and experimental data obtained in the millimeter-wave region is also presented.     

Capture Effect of Randomly Addressed Polling Protocol

The capture effect, discussed in this paper, is generally considered to enhance the system's performance in a wireless network. This paper also considers the Randomly Addressed Polling (RAP) protocol in the presence of a fading mobile radio environment. Herein, a deterministic channel, which rules according to inverse power propagation law, is established to obtain the probability that one collided packet can capture the channel from distance distribution. Through the probability, we analyze the performance of the RAP protocol by using an embedded Markov chain. According to our results, the performance of the RAP protocol does not obviously change in terms of power control, implying that it can be more aptly applied in power control skill than other protocols.     

The Synchronous AM Problem in FM TV Transmitters

The FM sound signal of a broadcasting TV transmitter is usually affected by spurious AM caused by the resonators of the vision?sound combiner. A simple expression is derived which allows the quantitative evaluation of this unwanted effect. Since the frequency stability of the resonators is the only factor which falls within the control of the designer, some considerations are made regarding the mechanical design criteria to be followed in order to improve it.     

开关电源在调频广播发射机中的应用

本文给出开关电源在调频广播发射机中的应用实例,并对使用中产生的电流浪涌问题进行了讨论。     

An IF-to-Baseband Σ∆ Modulator for AM/FM/IBOC Radio Receivers With a 118 dB Dynamic Range

A single-bit fifth-order complex continuous-time IF-to-baseband SigmaDelta modulator for AM/FM/IBOC receivers is presented. The input IF is 10.7 MHz and the sampling frequency is 41.7 MHz. The modulator achieves a dynamic range of 118dB in AM mode (3 kHz BW), 98dB in FM mode (200 kHz BW), and 86dB in IBOC mode (500 kHz BW). The modulator's high dynamic range enables the realization of an AM radio receiver without a VGA and without an AM channel-selection filter, thereby reducing system complexity and cost. The elimination of the VGA also improves the sensitivity and the overall noise figure of the receiver. The modulator's spurious free dynamic range is 88 dB in the bandwidth from 25 to 525 kHz. The IM2 distance is 92 dB, and the IM3 distance is 91 dB. The ADC was fabricated in a one-poly five-metal 0.18-mum CMOS process with an active area of 6.0mm². It consumes 210 mW from a 1.8-V supply     

FM ACOUSTICS FM1811后级功放

据全球回报集团（GLOBAL REFUND）统计，2009年中国游客在法国总消费额达到1．55亿欧元，位居各国之首。而在国内旺盛需求的推动下．近几年奢侈品及高级消费品市场的价格也不断走高，记得几年前三四千即可拥有的LV手袋目前都已过万．而路易十三干邑在短短3年的时间里也已经身价翻番。     

Performance Analysis of Capture Effect in High Speed Wireless Networks

The influence of capture effect on the high speed wireless networks is investigated in this paper. A new garkov chain model considering capture effect for the binary exponential back-off scheme in the MAC layer has been proposed. A new throughput model used in the IEEE 802.11 networks is proposed Based on this new Markov chain model, and then we analyzed throughput impacted by the capture effect under different transmission speeds. The performance analysis shows the capture effect has more impact on the throughput of high speed wireless networks than that on the low speed wireless networks.     

数字化接收机中分数倍采样率转换的有效结构

中频数字化接收机最能体现软件无线电的思想,数字下变频是中频数字化接收机中不可缺少的部分.本文从分析采样率分数倍变换的直接结构着手,讨论了数字接收机中高效、可行的一种分数倍采样率变换结构,将串行的高速数据处理转换成并行的低速处理,使系统对速度的要求大大降低.     

Optical Detectors and Receivers

In this paper, I will review the subjects of optical detectors and optical receivers. I will do this from both a historical perspective and looking ahead toward useful progress that may occur in the future. I will focus, at times, on the lessons learned while performing my own research and development activities, and on how and why the technology has changed. I will share a few anecdotes, which will shed some light on the innovation process-at least as I experienced it.     

全新的数字式测试接收机

介绍了全数字式、认证级测试接收机PMM9010的原理、特点及应用.除输入端的信号预选器外,该接收机每一个电路都实现了数字化.测试范围从10 Hz～30 MHz(可扩展3 GHz或6 GHz).全兼容CISPR 16标准.仪器预置信号预选器、前置放大器、自动衰减器、四种检波器(峰值、准峰值、有效值和平均值)以及跟踪信号发生器等.测试过程符合相关标准的要求.其稳定的性能,免去了高昂的维护费用.仪器可添加4通道Click分析模块、蓝牙模块等.辅以不同的配件如LISN、电流电压注入探头和吸收钳等,可以完成所有的EMC传导、辐射测试.