256 qam

of the lower frequency, demodulation, channel decoding, multiplexing, decompression, Video coding and audio DAC, and sends the analog video/audio output signal to the TV set, thus realizes the interactive video/data information service. At present, the most influential digital broadcasting standards are DVB,DSS and large Alliance DTV, which DVB for satellite broadcasting, cable television and terrestrial broadcasting in different forms are divided into dvb-s,dvb-c and DVB-T. This scheme uses s

distribution network. It is finally delivered to the Cable Modem RF portal of the terminal device. CM performs 64/256 QAM demodulation on the sent RF signal, and uses the RS technology (Reed_Solomon) for Error Correction. After the MPEG operation, the signal is converted to a format that complies with the Ethernet transmission protocol, it is sent to the terminal PC through the Cable Modem Ethernet port.Af

following improvements after migrating to 802.11ac: Speed. The maximum speed of 802.11n data is 450 ~ 600 Mbps, which uses four wireless data streams to transmit traffic. The first batch of 802.11ac products also use the same wireless data stream, but it can achieve a maximum speed of 1 to 3 Gbps. By the end of, the next batch of 802.11ac products will achieve a peak speed of Gbps. However, the actual transmission speed depends on the client performance and distance. For example, a single data

In response to the ever-increasing number of smart devices, applications, and data, wireless networks are evolving rapidly, and the IEEE 802.11ad standard (also known as Wiig) will help. In the past 10 years, we have seen the evolution of 802.11, while Wiig is a step change that adds a new 60 GHz band to existing products: 802.11n operates in the 2.4 GHz and 5 GHz frequencies, while the new 802.11ac product operates in the 5 GHz frequencies. By using three-frequency products (for example, 802.11

. Compared with the 11n 64 QAM, 11ac has a higher density modulation scheme, reaching 256 QAM. In the Wave 2 stage, 11ac will adopt multi-user MIMO technology with the emission beam forming function. The basic concept of MU-MIMO (multi-user MIMO) is very simple: A 11ac access point can send data to four clients at the same time (the client must also support MU-MI

a common copper cable U1C and a U1R reference point. VTU-O and VTU-R are the VDSL transceiver located at the local end and the user end, respectively. The service Splitter, including HPF and LPF, separates the VDSL transmitted on the same pair of telephone copper cables from the narrowband service or ADSL. VDSL uses a wide spectrum, up to 12 MHz. The spectrum range can be divided into several downlink DS and uplink US frequencies. Commonly Used frequencies in the world are Plan997 and Plan998,

Beyond 11ac: Interpreting 802.11ad and 11ax Recently, an international chip giant announced the launch of a three-frequency 802.11ad chipset. It is understood that the chipset will be the core component of a home wireless router, it will integrate 60 GHz 802.11ad technology with 5 GHz and GHz 802.11ac. It is a three-frequency access point chipset. Now the question is, what is 802.11ad technology? The IEEE 802.11ad standard, also known as wiggg, shows its origins with 802.11 by its name. In con

technology to reduce the impact of line damage on transmission performance.ADSL adopts discrete multiple audio modulation (DMT) technology and antisymmetric carrier modulation, which is an orthogonal frequency division multiplexing technique. The greatest advantage is that the signal can be sent and received by using efficient fast Fourier transform (FFT) and Inverse transform (IFFT) to complete the QAM signal and digital form of the subcarrier signa

user communicates with a PSTN user, the IAD user accesses the IP bearer network through the WIMAX wireless link, which is controlled by the media gateway controller Huawei SOFT3000) and sends the media stream to the integrated media gateway Huawei UMG8900 ), UMG8900 and PSTN Programmable switch Huawei CC08) have a direct circuit to complete communication. When IAD users perform voice communication, they are controlled by the media gateway controller Huawei SOFT3000) and communicate through the

802.11ac and 11n standard? To put it simply, the 802.11ad standard, also known as Wiig, can be considered as the next generation standard after 11ac and 11n. Compared with 802.11n (working in the GHz and 5 GHz frequencies) and 802.11ac (working in the 5 GHz frequencies), 802.11ad operates in the 60 GHz frequencies, making it easy to transmit data to 7 Gbps, it is three times faster than the current fastest 11ac theoretical transmission rate (5 GHz band, 2167 Mbps! Of course, if you are familiar

The 802.11ac standard is mainly designed to provide high throughput in the 5 GHz band, in addition to bringing fast and high-quality video streams, it also provides almost instantaneous data synchronization jobs and backups for laptops, tablets, and mobile phones. Theoretically, this specification will achieve at least 1 Gbit/s of multi-site WLAN throughput and at least 500 Mbit/s of maximum single-link throughput. This is achieved by expanding the air interface concept adopted by 802.11n: wider

The 802.11AC standard is designed to provide high throughput in 5GHz bands, in addition to bringing fast, high-quality video streaming, and providing almost instantaneous data synchronization jobs and backups for laptops, tablets and mobile phones. In theory, this specification will achieve at least 1gbit/s throughput of multiple-station WLANs and at least 500mbit/s maximum single link throughput. This is accomplished by expanding the concept of the air interface adopted by 802.11n: wider RF ba

, for sudden strong business flow, then choose TDMA mode; (3) The modulation mode of LMDS system is divided into two kinds of orthogonal phase shift keying (QPSK) and orthogonal amplitude modulation (QAM), in which QAM mainly adopts 4-qam, 16-qam,64-qam and so on, and the m

(): MSG. Find ('\ 0 ')); Qregexp rx ("Content-Type: [A-Za-z0-9 $! */\-] *) ");Rx. Search (messageheader );Qstring type = Rx. CAP (1 ); If (type = "application/x-msnmsgrp2p ") { unsigned int startbinheader = 0; bool justcr = false; while (startbinheader { startbinheader ++; If (MSG. data () [startbinheader] = '\ n') { else justcr = true; } startbinheader ++; } If (! Justcr | startbinheader + 48> MSG. Size () return; // No binary header, or not long enough, todo: Err

-(Void) udp_sendfile :( nsstring *) filename; { Nsstring * filepath = [nstemporarydirectory () stringbyappendingstring: Filename]; Nsdata * sdata = [[nsdata alloc] initwithcontentsoffile: filepath]; Byte * Sarr; Int sumpak, curpak; // Subpacket Transmission Int Total = sdata. length, curloc, srctotal = sdata. length; Sumpak = srctotal/8000; If (srctotal % 8000 = 0) { } Else { Sumpak = sumpak + 1; } Curpak = 0; Curloc = 0; Nslog (@ "Total: % d", total ); // File Information header: Ea filetype

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

At present, China's broadband access network has developed very mature and many new technologies have emerged. Here we introduce the development status of VDSL and analyze some of its problems, I would like to share it with you here and hope it will be useful to you. 1. Technical Standards of VDSL VDSL currently has two major incompatible technical standards: one is DMT discrete multi-audio modulation, and the other is CAP and QAM without carrier ampl

O-OFDM System Structure 1 is shown. The original binary sequence is mapped to N parallel sub-carrier channels through string/and conversion. At this time, the data cycle of each modulated sub-carrier is expanded to N times that of the original sequence, latency expansion and the numeric ratio of the symbol period are also reduced by N times. After the QAM modulation is performed on the sequence of each sub-carrier channel, the Fourier inversion IFFT

and demodulation techniques are described below.Quadrature amplitude Modulation (QAM)In modern communication, it has been one of the focus of attention to improve the spectrum utilization. Quadrature amplitude modulated QAM (quadrature amplitude modulation) is a kind of modulation method with high frequency spectrum utilization, which has been widely used in medium and large capacity digital microwave comm

The convolution parameters of some classical CNN structures have been statistically studied. Alexnet Layer Input Kernel Output Stride Pad 1 256 * 3 * 227 * 227 48 * 3 * 11 * 11 256 * 48 * 55 * 55 4 0 2 256 * 48 * 27 * 27 128 *