dqpsk modulation

Coding2.1 Digital Sound Signal(1). Frequency of Sound:　　　　(2). Sampling--Quantization--code:Sampling frequency: The Nyquist theory states that the sampling frequency should not be less than twice times the maximum frequency of the sound signal, so that the voice can be restored to the original sound as a digital expression, which is called lossless digitization (lossless digitization) Sampling accuracy: Number of bits per sound sample (bps)Amount of data (Bytes/sec) = (sampling frequency (Hz

usage would be confusing. Mute to (temporarily) force volume to is zero, independently from the usual volume controls. Pcm Pulse Code modulation, the most common low-level encoding of digital audio. The audio signal is sampled at a regular interval, called the sample rate, and then quantized to discrete values within a Particular range depending on the bit depth. For example, for 16-bit PCM, the sample values is integers between-32768 and

, it is quite far from the high-definition digital TV.High Definition Digital TV (HDTV) is the future development direction. By now, all analog TVs have been eliminated, and TV Station shooting, recording, and editing devices have also been replaced, what people will see on TV screens will be high-definition TV pictures and more functions. HDTV will bring TV into a new era.Someone asked if the current digital set-top box receives a high-definition digital TV signal? No. After a digital set-top b

means that the carrier frequency is changed according to a certain pattern (sequence) within a very wide band. Information Data D enters Carrier Modulation after it is modulated into a baseband signal with BD bandwidth. The carrier frequency is controlled by the pseudo-random code generator and is randomly changed in the bandwidth BSS (BSS> BD) band, the bandwidth of the baseband signal BD is extended to the bandwidth BSS used for transmitting signal

power and average power in the entire burst range at low, medium, and high frequency points. The specifications require that the peak power and average power be smaller than 23dbm and 20dbm respectively and meetThe following requirements: If the EUT power level is 1, the average power>0 dBm; if the power level of EUT is 2,-6dbm (2) power density The initial state is the same as (1). the tester finds the highest-power frequency point within the MHz band by scanning the frequency point, and then

supports multiple European languages and hybrid display of simple images and texts. Chapter 2 Composition of the DVB System[This article does not describe the hardware structure of the DVB system in detail, but explains in detail the format and Reuse Principle of the TS code stream according to the description in iso13818. (Enough, Enough)]Classification of DVBAccording to the application of different DVB, mainly divided into DVB-S, DVB-C, DVB-T, DVB-H and other specifications. Different Specif

HSPA is a new feature introduced by WCDMA R5. It uses high-order modulation of 16QAM and multi-Code Time Division Technology, greatly improving the packet transmission rate. High-order modulation: Higher-Order modulation can make transmission more efficient, but higher-order modulation also requires greater power and h

Broadband access technology is still quite common, so I have studied the two new broadband access technologies that are currently emerging. I would like to share them with you here and hope they will be useful to you. In the past decade, two new modulation and demodulation technologies, Cable Modem and ADSL Asymmetric Digital user line, have emerged. Cable Modem implements data transmission up to 10 mbH/s on a hybrid optical fiber/coaxial network (HFC

With the continuous development of the Communication Industry, broadband access technology is constantly being innovated. Here we will introduce two new access technologies and make a detailed comparison, I believe that the access industry will develop better in the future. In the past decade, two new modulation and demodulation technologies, Cable Modem and ADSL Asymmetric Digital user line, have emerged. Cable Modem implements data transmission up t

radio technology, you can use an average power less than 1 MW to cover a few miles, or even use a low-gain antenna. It is particularly valuable that it has low Interference Characteristics and strong multi-path interference resistance to other wireless systems. It is easier to implement than to build a common spread spectrum system, with a low cost. It is precisely because of the above features that the UWB communication technology has been widely used in personal communication, intra-building

standards. 802.1lb uses the KNN modulation technology to increase the data transmission rate, up to 11 Mbit/s. However, if the transmission rate exceeds 11 Mbit/s, it is very difficult to implement a more complex balance and modulation function to combat multi-path interference. Therefore, in order to promote the development of the wireless LAN, The 802.1l Working Group also introduced 0ofdm

RFID (Radio Frequency identification): A tutorialcontents: Introduction to Radio Frequency Identification-rfid What is RFID Compare RFID with Bar Code technology Benefits of RFID Disadvantages of RFID Active and Passive RFID Systems RFID Frequencies Operation of RFID Systems RFID Building Blocks RFID Tag block schematic, and operation Backscatter modulation RFID Standa

Pulse width modulation (PWM) is the abbreviation of English "Pulse width modulation", referred to as pulse width modulation. It is a very effective technology to control analog circuits by using digital output of microprocessor, which is widely used in many fields such as measurement, communication, power control and transformation. A simulation control mode, ac

segment, wide bandwidth, high speed, high spectrum utilization: With the diversification of user business, especially broadband, the information rate of the past Kbps or more than 10 kbps is not enough, many users require dozens of Mbps information rate. To improve the information rate, in addition to the use of advanced duplex technology, coding technology and modulation technology, the most basic is the wider channel bandwidth, the corresponding ne

adjustment unit can quickly track the channel change and adjust the rate by adopting different coding modulation schemes. When the channel condition is better, the Hs-dsch adopts a more efficient modulation method--16QAM to obtain higher frequency band utilization. Theoretically, although the XQAM modulation method can improve the channel utilization, but becau

What is a frequency converter. The frequency converter is the power control device which transforms the power frequency supply into another frequency by using the switching function of the electric semiconductor device. The frequency converter is the power control device which transforms the power frequency supply into another frequency by using the switching function of the electric semiconductor device. Can be divided into AC-ac frequency converter, ac-Straight-AC frequency converter. AC-Fre

-purpose system and the dynamic range of the useful signal change greatly. In the case of more than 50dB and different ambient power differences, it is not enough to achieve 1mb/s above rate, only by encoding and processing gain. Conversely, it is easier to avoid interference because the signal can be sent when the frequency (or time) is not disturbed (or when the interference is low). If the time-avoiding interference method is used, the signal sent will be aborted when the pulse interference i

Study on the Influence of optical fiber nonlinear effects on optical OFDM signals (1) Optical Orthogonal Frequency Di-vision Multiplexing (O-OFDM) is a new type of Optical transmission technology that has been developed in recent years, it applies Orthogonal Fre-quency Division Multiplexing (OFDM) technology to optical fiber channels. Transmitting OFDM Signals in optical fiber channels can improve the spectrum utilization and resist dispersion and various noise interference, with higher transmi

IntroductionThe PDM represents the pulse density modulation. However, a better abbreviation is "1-bit oversampling audio" because it is simply a high-sample-rate, single bitrate digital system. If you are looking for an advantage, it is that the sample rate is several times the audio CD, and a proper way to reduce the word length from 16bit to 1bit, which will be the basis of a PDM system.Most modern digital audio systems use multi-bit PCM (pulse-code

scene of the accident. If a serious accident occurs in the tunnel, a fire may occur, therefore, after an accident occurs in the tunnel, an emergency evacuation broadcast system is urgently needed. FMFM broadcast in the tunnel is a good emergency broadcast. Drivers can obtain evacuation and emergency command information through the radio, this service provides emergency incident command and handling to guide drivers to avoid risks. Therefore, whether in terms of security or service to the work a