qpsk modulation

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4B/5B Coding principle

scheme used in the optical Distributed Data Interface (Fddi,fiber distributed-Interface) of the Gigabit Fast Ethernet. This encoding is characterized by the data stream to be sent every 4bit as a group, each four-bit binary code is represented by 5-bit encoding, this 5-bit encoding is called the code group, and is transmitted by NRZI mode.In the communication system, the communication speed and the modulation rate in the transmission line, the so-cal

How PCM works

PCM Definition PCM Chinese called pulse code modulation, composed of. rivers proposed in 1937 that this concept laid the foundation for digital communication. In 1960s, it began to be applied to the local telephone network to expand the capacity, so that the transmission capacity of most existing audio cable core lines was increased by 24 ~ 48 times. By the middle and end of 1970s, various countries have successfully modulated pulse codes for large a

Lora and LoRaWAN Technology Overview

1. Introduction The purpose of this article is to provide a guided technical overview of Lora and LoRaWAN technologies. Low-Power wide area network (Lpwan) supports the vast majority of IoT devices that are expected to be hundreds of millions of orders of magnitude. LoRaWAN optimizes the battery life, capacity, range, and overhead of Lpwan in a bottom-up manner at design time. This paper gives an overview of the LoRaWAN norms in different regions, and compares several competing technologies in

Analysis of WCDMA transmitter

transmitter parameters and their importance in the design of the transmitter. Proximity channel power ratio [ACPR]:ACPR measures the size of the interference or adjacent frequency channel power. Typically defined as the ratio of average power in the adjacent channel (or offset) to the average power in the transmitting channel, ACPR describes the distortion caused by the nonlinearity of the transmitter's hardware. ACPR is critical for WCDMA transmitters, because CDMA

Creating a it++ application in the visual Studio 2010 environment

:\\itpp-4.2\\lib";var Itpp_inc_path = "c:\\itpp-4.2\\"; ) B. Copy all the files in the Vcprojects folder that you extracted from step one to the path C:\Program files (x86) \microsoft Visual Studio 10.0\vc\vcprojects, you will be prompted to overwrite , select ' OK ' for all. Third, open VS2010, New project, select Vc++\win32 Project, you can see the it++ option. Create a new it++ project. You can see that the it++ installation is successful, but the compile time does not pass, the key is

Comparison of wireless network technology

International standard update and improve, Further standardizing the development and application of products with different frequency points and higher network rate products, in addition to the content of original IEEE802.11, the Management Information Base (MIB) based on SNMP (Simple Network Management Protocol) protocol is added to replace the management information base of the original OSI protocol. In addition, high-speed network content has been added. IEEE802.11 points ieee802.11a and iee

No line by the correct knowledge of the channel

conflict. And many users use the wireless device default settings are Channel 1, when more than two of such wireless AP devices "Encounter" when the conflict is inevitable. Why is the current wireless channel conflict so interesting, in addition to home or office wireless equipment because the price of the constant decline in the geometric growth, wireless standards of the innate lack of shake is also a major cause of this dilemma: As we all know, the current mainstream wireless protocols ar

JPEG format compression algorithm

I. Overview of the JPEG principle Second, the JPEG principle detailed analysis and the compression algorithm process 1. Color model Conversion (color models) 2. DCT (discrete cosine Transform discrete cosine transform) 3. Data quantification 4. Reorder DCT Results 5. DC coding based on differential pulse coded modulation 6, RLE Code 7. Paradigm Huffman Coding 8, JPEG compression process summary

ADSL Technology Detailed

design, and DMT by the Amati communications company invented, the difference is the way to send data. ANSI Standard T1.413 is based on DMT, DMT has become an international standard, and Cap is a great decline. Recently, many of the g.lite standards are very good, but DMT and g.lite two kinds of standards have their own strengths, respectively, applicable to different fields. DMT is a full speed ADSL standard, which supports the high speed downlink/uplink rate of 8mbps/1.5mbps, but the DMT requi

Several schemes for realizing access network

the analog user access part hinders the development and forms the bottleneck effect. In this case, xDSL technology appears. At present, XDSL mainly refers to three kinds of HDSL, ADSL and VDSL.2.1, HDSL TechnologyDSL (digtal subscriber lines, digital Subscriber line technology) is the product of the late 80, mainly used for ISDN basic rate service, on a twisted pair to obtain Full-duplex transmission, using the technology is time compression multiplexing (TCM) and echo cancellation. However, cr

Asymmetric Digital subscriber Line (ADSL) (1)

actually an acronym for the term modulation/demodulation (modulation/demodulation). Modems allow two computers to communicate with each other using a public switched telephone network. The public switched telephone network can only transmit voice signals, so modems need to convert the computer's digital information into a series of high-frequency voice signals that can be transmitted over a telephone line.

How to maintain good CDMA network

receive backup antenna. The downlink interference measurement can be carried out in the coverage area of the base station. You can use directional or indefinite antennas. It may take a long time to measure the interference of a base station that cannot interrupt the business. Measure interference in the business silent clearance. The best way to locate the radio frequency deviation of the base station is to use the base station transmitter tester to test the RF indexes such as power, frequency

Coding and decoding study notes (3): Mpeg1 and Mpeg2 in Mpeg Series

is the modulation method, because the frequency and bandwidth requirements for different applications are different. The DVB-S of high-frequency carrier is used to use the PSK modulation method, the DVB-C of low-frequency carrier is used to use the QAM-64 modulation method, and the DVB-T of high frequency carrier and ultra-high frequency carrier is used to use t

Mobile Network Cottage Edition (OPENBTS) "2" band Story

), while Morse code carries information that needs to be transmitted. Spark gap mode generated by electromagnetic waves, occupy the entire electromagnetic spectrum, so a mountain not two tigers, the only possible way of cooperation is that we take turns Republicans.This dilemma, finally in 1906, was a breakthrough by Canadian prodigy Reginald Fessenden. Fessenden, only 14 years old, has shown a prominent mathematical genius, was assigned to the school assignment mathematics, to other children cl

Computer Network Principle calculation questions

1. Set the channel bandwidth to 3400Hz and adopt PCM encoding. The sampling period is 125b/S. If the sample size is 128, the data rate of the channel is ()? Resolution:The sampling period is 125b/s, so it is 8000Hz, that is, F = 1/T = 1/0. 000125 = 8000Hz, 128 quantization levels, requires 7-bit encoding (that is, the 7th Power of 2 ). R (data transmission rate) = 1/T * log2n = 8000*7 = 56kb/s ---> B (modulation rate) = 1/T baud PS. Because the sampli

Developers must understand the concept of switching power supply (features of the Power Supply Module)

performance. More and more applications are applied to modern electronic technology, also known as the module power supply. Is currently the main direction of power development, smaller, more efficient, more stable ---- High Integration, higher efficiency, and more powerful functions are currently the main development direction of Power Supply Modules Of course, the input of the switching power supply is not limited to AC (AC/DC power supply), but also DC (DC/DC power supply and DC/AC power

Do you know the advantages and disadvantages of regulated power supply?

adjusted by the duty cycle of the excitation signal. The voltage variation of the input signal can be compensated by frequency modulation or Width Adjustment, when the power frequency grid voltage changes greatly, it can still ensure a stable output voltage. Therefore, the voltage regulation range of the switch power supply is very wide, and the voltage regulation effect is very good. In addition, there are two methods to change the duty cycle: Pulse

DirectX 8.0

more suitable for creating video editing applications. You will benefit from it as an application developer. Des replaces the cut table, and the cut table is no longer supported. Two new interfaces, idvdcontrol2 and idvdinfo2, greatly expand the functions of the DVD navigator. The DVD navigator now implements a complete command set of the DVD Annex-J, which can play either the karaoke or the album. The new mswebdvd ActiveX Control enables this feature to be used in script-based applications. Th

Capture/compare Channels

Each capture/compare channel is centered around a capture/compare register (including the shadow register), including the captured input (digital filtering, multiplexing, and pre-divider ), and the output part (comparator and output control ). The capture/compare module consists of a preload register and a shadow register. Only the pre-loaded registers are operated during the read/write process. In the capture mode, the capture occurs in the shadow register and then copied to the pre-loaded regi

Introduction to GSM mobile phone principles

generally becomes the 2.75 generation network. Is a GSM source code and channel code. The principle diagram of the GSM mobile phone is as follows: The circuit structure of a mobile phone (hereinafter referred to as a mobile phone) can be divided into four parts: Wireless, transmission and processing, interface, and power supply. The circuit principle can be summarized into two parts: RF circuit and Baseband circuit.1. Wireless partIt includes antenna circuit, transmission, receiving,

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