dqpsk modulation

Shanghai Bell Company's Cablelink Cable modem system provides high-speed asymmetric data communication services to users through the fiber coaxial hybrid network. The asymmetry of its connections requires high-speed communications in one direction, such as network browsing, Internet file transfer, and ideally in the opposite direction with a lower-rate delivery service. The TDMA access method used in Cablelink 2000 system can make the system more flexible when it is enlarged. On the front end, t

The above section says analog signal analog carrier modulation, this section says the following analog signal digital carrier code. Digital transmission of analog signals The analog signal is sampled-quantified-encoded into a digital signal into the channel transmission Sampling: processing a continuous signal over time into discrete signals in time It should be noted that the Neiguist sampling theorem, that is, the sampling frequency is not less than

Tags: class blog http tar ext comSource: http://blog.csdn.net/kk185800961/article/details/12350715 Reprint Please specify the sourceXML instance file: XML version="1.0" encoding="Utf-8" ?> Root > Frame > Item > ID > 0 ID > Num > 1 Num > rs_rate > (240,240) rs_rate > Mode > AA Mode > Rate > the Rate > modulation > BPSK modulation > T

MCS (modulation and Coding scheme, modulation and encoding strategy)The configuration of the 802.11n RF rate is achieved through the MCS index values. The MCS modulation encoding table is a representation of the 802.11n to characterize the communication rate of the WLAN. MCS takes the factors that affect the communication rate as columns of the table, and the MCS

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

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

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

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

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

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

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.