pam4 modulation

electrical characteristics of the transmission media, generally, different transmission media have different processing capabilities for signals in different frequency segments. The ethernet cable processes the baseband signal, and the wide area network light emits high-frequency modulation signals. Mobile Communication, 2G and 3G require different carrier frequencies. Can these media (air, wire, optical fiber, etc.) input at a certain frequency be b

Win7 Network connection error code 629 workaround. The method is as follows: 1, check user name and password: If your username and password input error, it is likely to cause 629 errors, we can re-enter the user name and password, enter the time to see if your key is open to enter the user name error, enter the completion of the user name, to see if there are more than a space. 2, the replacement line: Connecting the network line aging or crystal head failure may cause us to conn

Basic Process non-static methods Get byte code (FINDCLASS)Get Method (Getmethodid)Instantiation of the Class (Allocobject)Call Method (Callintmethod) static Method Get byte code (FINDCLASS)Get Method (Getstaticmethodid)static method of calling method (Callstaticvoidmethod) non-static method C code addint (int a, int b) method in Java class Java code: public int AddInt (int a, int b) { int c = + b; Toast.maketext (Mainapplication.getcontext (), "calculated result::" +c, Toast

a string, such as the key in the following code that describes the names of the chapters in the course "Communication basics" with a more meaningful string, which is an associative array:$chapter = Array (' Chapter One ' => ' Communication system Overview ',' Chapter II ' => ' communication protocol ',' The third chapter ' => ' Transmission technology ',' Fourth chapter ' => ' modulation mode ');Here is the code to output the two types of arrays, thi

HSDPA and HSUPA are now regarded as the evolution direction of WCDMA. The new modulation coding method in HSDPA will greatly improve the user data rate and throughput, which means that the spectral efficiency is enhanced. At the same time, users can get faster connection speeds. Therefore, from the operator's point of view, if compared with the existing 3G technology, HSDPA can be on the same wireless carrier service more high-speed users. Compared

, to meet the needs of data communication, has a strong application value. 1 Ethernet-based laser wireless communication system The combination of Ethernet and laser wireless communication can give full play to the advantages of the two systems and improve the application range and reliability of the system greatly. Fig. 1 is a schematic diagram based on one end of the Ethernet laser wireless communication system, and the other end of the structure and the end of the symmetrical state. From

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.

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

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

bandwidth--greater bandwidth allows for more information to be sent in a shorter period of time. Another wireless technology with 250kbps bandwidth, for example, needs to be turned on for 8 times times longer to send the same information (consumes more battery power).Bluetooth Low energy Technology "complete" a single connection (that is, scanning other devices, establishing links, sending data, authenticating and ending appropriately) is only 3ms. Standard Bluetooth technology requires hundred

is directly output to the multipleer without the video server. C. Video Server The video server uses a large array disk to store audio and video streaming files, effectively manage the program editing process and material library, prepare program series orders, and broadcast multiple programs through the broadcast control platform. 　　　　 D. DTS The multi-channel MPEG-2 data transmission stream (SP, single-program TS) from the video server and real-time Encoding Equipment is reused as one-way t

operator is different, but the function is the same. Its main content is that the operator provides the classification and system settings of the business (Program) and some auxiliary functions. These contents constitute the top menu of the page, and the next menu is usually composedSiGeneratedEPG. In the main menu, the system is set to enable the receiver to receive messages quickly and accurately.DVBThe program has three basic operations: information detection, program search, and software d

With the development of digital signal processing technology, more and more electronic products are using digital audio technology. Digital audio interfaces have become a trend of development. The ECM and MEMS digital microphones using pulse density modulation (PDM) interfaces are also born. Currently, ECM and MEMS digital microphones have become the mainstream for portable laptop sound pickup devices. Digital ECM or MEMS microphones have irreplaceabl

(high power consumption) L self-interference system-mutual interference between users in the system, difficult technical implementation 3: What is the voice encoding used by TD? A: Amr (Adaptive multi-rate) has eight types of codes. 4: In the TD system, which code is used to differentiate users and communities? A: differentiate users: Spread spectrum codes. The spread spectrum codes used by TD are OVSF codes. L The uplink spread spectrum factor used by the TD-SCDMA is 1/2/4/8/16, with the beha

the system file in windows to the VC ++ project directory, and then include the file matlib. h and the linked file v1_1.lib in the program. After the installation of matcom, the refguide.pdf file is automatically generated on the installation terminal. the functions listed in the file can be directly used in VC ++.2. Use MATLAB mathematical functions and Toolbox FunctionsAfter completing the above steps, you can use MATCOM to convert the M file of the required function to a CPP file or DLL file