Digital Separation and Reconstruction of NTSC Signals

A new digital method for separation and reconstruction of NTSC color TV signals is described. Digital conversion between an NTSC signal and its baseband component signals is performed at a sampling rate of(12/5)f_{sc} simeq 8.59MHz (fsc: the color subcarrier frequency), which is lower than the conventionally used3f_{sc}or4f_{sc}sampling rate. Since this lowered sampling rate satisfies the Nyquist condition for NTSC signals, the proposed digital method can provide an effective technique for the component coding of NTSC signals. Simulation results have shown that, with this method, no visible picture quality degradations can be observed for either the color bar signal or SMPTE Pictures.     

An ADPCM Receiver for NTSC Composite Video Signals

An ADPCM codec for carrying one broadcast quality NTSC color TV channel at a bit rate of 42.9 Mb/s has been proposed. The system uses 3 fsc sampling, adaptive intrafield contour prediction, adaptive quantization., 4/8-bit dual length coding, and horizontal blanking interval suppression techniques. The receiver of.the video codec is designed and implemented in ECL for recovery of the original signal. The receiver accepts.a 42.9 Mb/s serial data stream with a synchronous clock from the transmitter. The receiver detects the line synchronization code, demultiplexes the audio signal and video signal, and generates the horizontal blanking patterns which have been removed at the transmitter side. The 4/8-bit dual length code is decoded and fed to the ADPCM reconstruction loop to obtain the reconstructed active video signal. The generated horizontal blanking pattern is multiplexed with the reconstructed video=signal and sent through a D/A converter to form the reconstructed analog NTSC composite video signal.     

Movement Compensated Interframe Prediction for NTSC Color TV Signals

This paper presents techniques for interframe prediction of color NTSC signals using motion estimation and compensation techniques. A key element in movement-compensated prediction is the displacement estimation algorithm. A number of techniques for performing this estimation have been presented in the literature [1]-[13]. Some new techniques giving improved performance are presented in this paper. Also, a movement-compensated composite prediction approach for coding of the NTSC color signals is presented. The performance of different displacement estimation algorithms is evaluated and compared for both component and composite approaches. A database of several color NTSC video sequences is used in the evaluation.     

Orthogonal Transform Coding System for NTSC Color Television Signals

A two-dimensional, 32nd-order orthogonal transform coding system which performs three types of transformations in realtime for NTSC color television signals has been developed. This paper reports on a hardware realization of this system, the optimum bitassignments for 32 and 22 Mbit/s transmission rates and the effects of bit errors during transmission. Through the evaluation of picture quality, the system gave a fine quality of pictures after compressing an 8-bit digitized television signal into 3 bits/pel corresponding to 32 Mbit/s transmission, and a passable quality of pictures by 2.25 bits/ pel corresponding to 22 Mbit/s transmission.     

微分相位校正电路的工作原理分析

微分相位失真是由传输系统的非线性引起的,它会造成彩色图像信号随亮度信号变化而引起色调失真,电视信号在传输的过程中总存在着非线性,它不仅会产生微分增益失真,同时还会产生微分相位失真、互调失真等,着重介绍的是微分相位失真。     

Single-Sideband Distortion of NTSC Color Signals Due to Envelope Detection

Envelope detection of single-sideband signals produces distortion under some conditions. The color information in the NTSC system is transmitted as a single sideband. One effect of the distortion is to change the saturation of colored areas. The change in saturation is calculated for a standard color-bar signal.     

DPCM Coders with Adaptive Prediction for NTSC Composite TV Signals

New adaptive differential pulse code modulation (ADPCM) coders with adaptive prediction are proposed and compared with existing nonadaptive DPCM coders, for processing composite National Television System Commission (NTSC) television signals. Comparisons are based on quantative criteria as well as subjective evaluation of the processed still frames. The performance of the proposed predictors is shown to be independent of well-designed quantizers and better than existing predictors in such critical regions of the pictures as edges and contours.     

Effects of Digital Demodulation on Component Coding of NTSC Color Signals

Effects of nonideal filtering in the digital demodulation of the composite NTSC signal into luminance and chrominance components on the coding of the luminance component are discussed. The residual chrominance component is shown to cause degradation in prediction and/or motion detection algorithms which are based on line or frame difference signals. Simple techniques for reducing these effects using chrominance-band rejection filters are presented and the efficacy of these methods are verified by simulation.     

A Motion-Compensated Interframe Coding Scheme for NTSC Color Television Signals

A motion-compensated interframe coding system for an NTSC color television signal has been developed. The output of a local decoder is used in the form of aY/Cseparated signal. Motion vectors are detected using theYsignal, and theYsignal and both baseband components of theCsignal are motion-compensated. The motion-compensated signals are reencoded into an NTSC signal to provide a motion-compensation interframe prediction in the NTSC format. Real-time experimental hardware has been built. The sampling frequency and bit rate of this system are 10.7 MHz and 1.6 bits/ sample, respectively. This value includes all overhead information such as motion vectors and other control information. An assessment has been made of the picture quality of coded/decoded pictures taken from a variety of broadcast television programs. The quality was good for almost all the programs. A subjective test of picture quality was performed under stringent conditigns. The lowest value for the picture quality of the most difficult scenes at 1.6 bits/sample was 3.3 on a five-grade impairment scale.     

利用FFT校正两个密集信号的频率和相位

在一个频率分辨单元及其附近只存在一个频率信号时,对频率和初相的校正有多种方法,如三点卷积校正法、幅度比值校正法和相位差法。而在一个频率分辨单元及其附近存在两个频率信号时,上述方法均告失效。目前人们提出识别和搜索方式,但这种处理不利于快速计算。本文在分析相位差法和幅度法的基础上,给出了直接计算。仿真结果证明这一方法简单有效,而且可以推广到同一频率分辨单元存在两个以上频率信号的情况。     

Design of Amplitude and Phase Modulated Signals for Differential Space-Time Block Codes

A differential space-time block code (DSTBC) provides full diversity advantage and does not require any radio channel estimation in the receiver, which makes it an attractive alternative to the well-known coherent space-time block code (STBC). However the original design of DSTBC allows only pure phase shift keying (M-PSK) modulation scheme, which are not optimal for M > 4. In this paper a simultaneous amplitude and phase modulation scheme for DSTBC with 2 transmit and several receive antennas is introduced. The performance of the proposed scheme is investigated and compared with DSTBC techniques using pure M-PSK modulation. Alexandre Vanaev received B.Eng. degree in Electrical and Electronic engineering from the St. Petersburg State Polytechnic University, Russia in 1998, and M.Sc. degree in “Information and communication systems” from Technical University Hamburg-Harburg in 2002. He is currently pursuing his Ph.D. in the Technical University Hamburg-Harburg, Department of Telecommunications. His research interests include prospective OFDM-based wireless communication systems and MIMO technology. Prof. Hermann Rohling is with the Technical University Hamburg-Harburg, Germany where he has developed an international reputation for Mobile Communication (4G) and automotive radar systems. Previously Prof. Rohling was with the AEG Research Institute, Ulm as a researcher working in the area of digital signal processing for radar and communications applications. His research interests have includedWideband Mobile Communications especially based on Multicarrier Transmission Techniques (OFDM) for future broadband systems (4G), signal theory, digital radar signal processing, detection, estimation and differential GPS for high precision navigation. Prof. Rohling is a member of Informationstechnische Gesellschaft (ITG), German Institute of Navigation (DGON) and a Fellow of IEEE. He is a chairman of the September 2006 International OFDM Workshop (InOWo 2006) and the International Radar Symposium (IRS 2006) in Krakow, Poland. Prof. Rohling is theVice President of the Technical University Hamburg-Harburg.     

Digital TV Receiver for NTSC Color TV Signals with Dual Word-Length DPCM Coding

A video codec system for carrying one broadcast quality NTSC color TV channel at a rate of 42.935 Mbits/s has been proposed. The receiver of the video codec system is developed for recovery of the original signal. The receiver accepts a 42.935 Mbits/s serial TDM data stream with a synchronous clock from the Transmitter. The receiver detects the unique sync code and inserts a horizontal blanking pattern which has been removed from the transmitting data. The audio and video data are separated at the outputs of the demultiplexer. The 4/8 bit dual length code word of the video data is smoothed out by a buffer memory and fed to the DPCM reconstruction loop. The analog NTSC color video signal as well as the audio signal are reconstructed after the D/A conversion. This paper describes the design and development of the receiver portion (Fig. 1) of the codec which is capable of transmitting'one color signal at broadcast standards on a T3 digital link.     

Separation of NTSC Signals by Minimum Mean Square Error Filters and Adaptive Filters

Two techniques for separating a composite NTSC signal into luminance and chrominance components are developed and compared. In the first technique, fixed filters, which are based upon minimum mean square error estimators, are designed. It is shown that, when samples from successive lines are used, these filters have a comb structure in the region of the frequency spectrum in which the luminance and chrominance signals overlap. In the second technique, the composite signal is filtered by several filters, and the outputs of the filters are selected dependent upon the local characteristics of the picture. Both recursive and nonrecursive filters are considered, the criterion for selecting between filters is investigated and the effect of delayed decisions is determined. The various filters are compared using subjective criterion and a number of quantitative criterion. The relationships between the quantitative and qualitative criterion are stated.     

基于双跟踪方式实现海上自动校相

在分析单脉冲跟踪系统特性的基础上,阐述了海上自动校相的重要性,说明了目前几种海上自动校相方案的不足,以及单脉冲跟踪方式与圆锥扫描跟踪方式的优缺点,并从工程应用的角度提出了基于双跟踪方式实现海上自动校相的方案。此方案充分利用了2种跟踪方式的优点,有效克服其缺点,实现了单脉冲跟踪系统海上自动校相,且使2种跟踪系统在硬件上高度共享,馈源网络实现兼容。此外,该方案大量采用现有成熟技术,有效降低技术风险性。     

On-Line Real-Time Digital Computer Separation of Extracellular Neuroelectric Signals

An on-line real-time spike recognition and separation system for up to six different spikes in multiple unit extracellular records has been developed using the Micro-LINC 300 computer. Assuming biphasic potentials, the computer extracts four unambiguous variables, two in amplitude and two in time. One variable of a selected pair is plotted against the other on the computer CRT. Points representing the same class of signal will fall into clusters. Cluster boundaries for spike separation are set visually by the investigator. Output is in the form of pulses on different relay lines. The system permits waveforms to overlap up to 15 percent. Examples of system performance with real signals are presented. A comparison is made with other spike recognition systems. A simple system is presented for generating artificial test signals and a technique described for testing any spike recognition system.     

32 Mbit/s Transmission of NTSC Color TV Signals by Composite DPCM Coding

A composite DPCM coding System was developed, which is capable of coding and transmitting an NTSC color TV signal without component separation at a 32.064 Mbit/s rate. The DPCM prediction method used is based on the algorithm that a luminance component prediction valuehat{y}and a carrier chrominance component prediction valuehat{c}are calculated individually, and then the composite signal prediction valuehat{x}is determined byhat{x} = hat{y} + hat{c}. In order to utilize horizontal blanking (HBL) intervals for transmitting active video signals,HBL signals are not transmitted in each line but their representative signals are transmitted once a frame during a vertical blanking interval. A dual word-length coding and quantizing method is adopted, which uses 4 bit and 8 bit words with average word-lengths of 4.4 bits/sample. Codec equipment was fabricated, and coding and transmitting experiments were conducted, using NTT's PCM-100 M digital repeatered line. Experimental results show that this composite DPCM coding system can be employed for digital transmission of NTSC color TV signals, such as color ITV signals, at a 32.064 Mbit/s rate.     

Transmission of Two NTSC Color Television Signals Over a Single Satellite Transponder Via Time-Frequency Multiplexing

We describe a time-frequency multiplexing (TFM) method for transmitting two television signals over one satellite transponder, which gives significant improvement over existing methods. The complexity of the hardware implementation is similar to existing time-division multiplexing (TDM) systems, but the picture quality, when received on a 10 m earth station, approaches that which is currently being requested by the major television networks. Unlike existing frequency-division multiplexing (FDM) systems, TFM needs no backoff of the satellite transponder. The general philosophy of TFM is described, including the benefits of using a difference signal to reduce the overall required bandwidth. Also discussed is companding of the difference signal as a means of improving the overall signal-to-noise ratio. Several alternative methods of implementation are considered, along with those which have been explored in some detail. We then describe an experimental TFM system which was implemented using digital field memories and tested with a 10 m earth station operating through the COMSTAR D2 satellite. Received picture quality was excellent in all cases. Weighted SNR was 53-56 dB, and in practically all instances subjects could not tell any difference between single-picture FM transmission and TFM dual-picture transmission.     

Experimental Validation of Timing,Frequency and Phase Correction of Received Signals Using Software Defined Radio Testbed

Recently, almost all the wireless devices are being designed for the fast evolving technology of software-defined radios, which is a radio access technology that most of the signal processing components are implemented digitally in software rather than in hardware to redefine the functionality of components, reduce the cost and complexity of the systems. This paper presents a low cost, portable, and flexible frequency hopping signal record and playback system based on a general purpose software radio front end, the Universal Software Radio Peripheral N210 devices. Further, this paper addresses the different issues such as timing recovery, phase recovery and frequency correction. In addition to that various GNU schematics are created to show the effect of different signal processing blocks on a modulated signal and their corresponding outputs are presented in the view of time domain, frequency domain and waterfall sink.     

有线电视基站相线和零线的检测与自动矫正

探讨了交流电网中相线和零线的正确接法以及相线和零线接反后所造成的危害，并给出了相线和零线接反时的两种自动矫正电路。     

Correction of Maxwell's Equations for Signals II

In the first of two companion papers it was shown that the addition of a magnetic current density to Maxwell's equations is a sufficient condition to obtain solutions in lossy propagation media for waves that are not infinitely extended periodic waves. The solutions obtained represented transients that may be used to represent signals having a beginning and an end. This second paper shows that the addition of a magnetic current density is also a necessary condition for the existence of transient solutions in lossy media. The modification of Maxwell's equations is thus necessary and sufficient for the study of the propagation of signals in lossy media.