qam modulation

This article transfers from the text/ Shing original reprint please indicate the source http://blog.csdn.net/yxstars/article/details/ 380799 Depending on the way the signal is sent and received, Iso/iec14443-3 defines the TypeA, typeb two card types. They differ mainly in the modulation depth of the carrier and the encoding of the binary number. When transmitting a signal from a read-write implement to a card, the two transmit the signal via a

802.11 standard802.11 standard Introduction:IEEE 802.11 is a common standard for today's wireless LANs and is the standard for wireless network communications defined by the International Institute of Electrical Engineering (IEEE).It defines the media access control layer (MAC layer) and the physical layer. The physical layer defines two types of spread-spectrum modulation and an infrared transmission on the 2.4GHz ISM band, and the total data transfe

spectral width. The average radial velocity is usually obtained by averaging dozens of pairs of pulses.8.1.4 Maximum non-fuzzy distance and distance foldingDistance folding: Refers to a radar to produce a radar echo of the target object of a recognition error. When the target is located outside the maximum non-fuzzy distance rmax, the radar shows the target in a position within the Rmax, which is called "distance folding" vividly.When a distance collapse occurs, the position of the echo shown b

technical characteristics of BluetoothTo put it simply, Bluetooth is a short-range wideband radio technology that is the global open standard for voice and data wireless transmission. It uses advanced techniques such as frequency hopping spread spectrum (FHSS), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA) and so on to establish the information transmission between various communication and information systems in a small scope.1, the main technical characteristics o

represented by 5-bit encoding, this 5-bit encoding is called the code group, and is transmitted by NRZI mode.The 4B/5B encoding is an information encoding 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

-contact displacement measurement.According to the principle of measurement, laser displacement sensor principle is divided into laser triangulation method and laser Echo analysis method, laser triangulation method is generally suitable for high-precision, short-distance measurement, and the principle of laser echo analysis is used for long-distance measurement.3 Measurement Method One: phase-type Laser rangingPhase Laser rangefinder is the frequency of radio waves, the amplitude

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

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

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

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

communication)-both parties to a communication can send information, but not both (and certainly not simultaneously). Two-way simultaneous communication (full-duplex communication)-both sides of the communication can send and receive information at the same time. Baseband signals (i.e. basic band signals)-signals from sources. Data signals such as computer output that represent a variety of text or image files belong to the baseband signal. Baseband signals often contain more low-fr