You never

You never experience runescape gold That's why it's e'er wow gold designer disagreeable. When wow power leveling he incoming looked up, he wow power leveling saw that the salesman was waiting to wow gold give. He had his caning confine .

CDMA wireless card
CDMA (Code Division Multiple Access), also known as CDMA, is used in wireless communications technology, CDMA allows all users to simultaneously use the full band (1.2288Mhz), and the issue of other users signal as noise signals do not have to take into account the impact (collision) problem. CDMA's advantages include: CDMA voice coding provided in the technology, than the current GSM call quality is good, but also the surrounding environment while the user dialogue noise reduction, so that the call clarity.
directory
professional technical standards defined in the technical background advantage of the system capacity with system capacity for better call quality and flexible configuration of network building frequency planning is simple and low cost network of green technology features low power spectral density of any is the CDMA mobile phone GSM CDMA mobile phone with the advantages of CDMA handsets on CDMA and GSM systems radiation transmission power requirements of mobile phone experience to describe and compare the results of road tests of radiation safety standards and mobile phone transmission power CDMA system, CDMA system, the concept of knowledge-CDMA system, CDMA system time drawback of CDMA CDMA system frequency use planning related Q & A the difference between CDMA and CDMA2000 1X radio research in open source projects GNU RadioOSSIECDMA
distribution network of China Telecom signs
professional definition of CDMA, is the use of spread spectrum communication technology, which can reduce interference between mobile phones,chi pink dazzle, and can increase the capacity of users and mobile phone can do the power is relatively low, not only can make use of longer, more importantly, people can reduce the harm of electromagnetic radiation. Larger bandwidth can be extended CDMA, you can also transfer images, which is why the selection of third-generation CDMA mobile phones causes. In terms of performance on safety, CDMA is not only a good certification system, but also because of its transmission, with a code to distinguish the user, preventing unauthorized listening ability was greatly enhanced. CDMA system is now rapidly developing. Wideband CDMA (WCDMA) wideband code division multiple access transmission technology, as an important basis for IMT-2000 technology, will be the third generation of digital wireless communication systems in the world. The emergence of technical background stems from CDMA technology on the human demand for higher quality wireless communications. During World War II because of the war
CDMA mobile phone
[1] research and development needs of the CDMA technology, its ideological enemy of one's own mind is to prevent interference with communications during the war, widely used in military anti- interference with communication, and later updated by the Qualcomm as commercial cellular telecommunications technology. In 1995,chi pink dazzle limited edition, the first commercial CDMA system (known as IS-95) after running, CDMA technology's many advantages in theory been tested in practice, which in North America, South America and Asia have been rapidly promoted and applied. Many countries and regions worldwide, including China, Hong Kong, China, Korea, Japan, the United States have built a CDMA commercial network. In the United States and Japan, CDMA become a major mobile communications technology. In the U.S., 10 mobile communications operators in seven selected CDMA. To April 2006, South Korea, 60% of the population as CDMA users. Australia hosted the 27th Olympic Games, CDMA technology is playing an important role. China Unicom on January 8, 2002 the official opening of the CDMA network and put into commercial use after 1 October 2008 transferred to the Chinese telecommunications operators, mobile phone number section for the 133,153,189 and 180 have not yet Telephone Number of the segment. Actress Heidi and her composer husband, Rama definition of Spectrum (Spectrum) concept back in 1942. The patent is an important concept proposed 50's, New York, Sylvania, Inc. (owner of Morris Chang of TSMC first job in the United States, that is, the semiconductor company) began to Heidi and George as the starting point for a patent related to research and development. Later in the '60s, the relevant spread spectrum (Spread Spectrum) technology emerged, the U.S. military began using in the military spread spectrum communication system technology. 80 After the Cold War, the U.S. military lifted the control on the spread spectrum technology, allowing it to commercialization. Then in 1985, the United States set up a small company in California, to spread spectrum technology, developed CDMAJI (Code Division Multiple Access) system. This company is a high-pass! Standardization of technical standards for CDMA technology has gone through several stages. IS-95 is the first of series of standards cdmaONE published standards, and truly has been widely used in the world's first CDMA standard is IS-95A, the standard supports 8K encoding voice services. Subsequently published in the 13K were the TSB74 standard voice encoder, support for the 1.9GHz CDMA PCS system STD-008 standards, including 13K service quality voice coding is very close to the wired telephone voice quality. With the mobile communications business growth in demand for data, February 1998, Qualcomm announced for CDMA IS-95B standards based platform. IS-95B CDMA system provides performance and increase user data traffic mobile communication devices, providing 64kbps data service support. Subsequently, cdma2000 a narrow-band CDMA system, the transition to third generation systems standards. the early stage in the standard of cdma2000, 1X and 3X proposed development strategy, but subsequent studies have shown that, 1X and 1X enhanced technology of the future direction of development. CDMA technology, standardization, and promote this technology in the world-wide application. Currently in the United States, South Korea, Japan and other countries, CDMA technology has been large-scale applications. In some European countries, some operators have built a CDMA network. According to CDG (CDMA Development Group, the world's) statistics, the end of 1996 only 100 million CDMA users; to March 1998 has quickly grown to 10 million; as of September 1999, the number of users has more than 4000 million. In early 2000 the global total number of CDMA mobile phone users has exceeded 50 million, the number of users in a year growth rate of 118%. CDG said the CDMA market in Asia has become the main driver of growth in Asia, the number of CDMA users increased by 88% a year earlier, reaching 28 million. U.S. growth rate is as high as 143%, reaching 16.5 million, but the absolute number of users is lower than in Asia, the Asia Pacific region, Hong Kong, Japan, Korea, Australia, Thailand, India, Philippines, New Zealand, Bangladesh and many other countries and regions have built a CDMA commercial network, has over 21 million users. The third is the growth rate in Central and South America, CDMA subscribers reached 500 million. CDG also said that future global CDMA market, mainland China's growth potential. CDMA mobile communication technology development. Stage in the 2G, CDMA and GSM Enhanced IS95A on the technical system in the same generation, providing substantially the same business. However, CDMA technology has its own unique, in the call quality, fewer dropped calls, low radiation, health, environmental protection and other significant features. In 2.5G stage, CDMA2000 1X RTT and GPRS technology has been significant in the differences in the transmission rate higher than on the 1X RTT GPRS, carrying on business in the new GPRS mature than 1X RTT, can provide more new business in the high-rate . From 2.5G to 3G transition on technical systems, CDMA2000 1X to CDMA2000 1X EV-DO GPRS to WCDMA transition than the transition smoother. The advantages of the system with a capacity theory, using the same frequency resources in the case, CDMA mobile network capacity than analog networks 20 times, the actual use 10 times larger than the analog network, 4-5 times larger than the GSM. Flexible configuration system capacity in CDMA systems, the increase in the number of users equal to the increase in background noise, resulting in a decline in voice quality. However, no limit on the number of users, the operator may be a compromise between capacity and voice quality considerations. In addition, between the multi-cell interference according to traffic and automatically balanced. The mechanism of CDMA features and relevant. CDMA is a self-interference system, all mobile users occupy the same bandwidth and frequency, an analogy, the bandwidth is thought of as a big house, all of them will enter only the big house. If they use a completely different language, they can clearly hear the voice of companion only talk by some interference from others. Here, the room air can be thought of as broadband carrier, and be deemed a different language code, we can continue to increase until the entire background noise limits on the user us. If you can control the user's signal strength, while maintaining high-quality call, we can accommodate more users. Better call quality TDMA channel structure can only support up to 4Kb of the speech coder, it can not support more than 8Kb speech coder. The structure can support 13kb CDMA voice codec. It can provide better call quality. Vocoder CDMA system can dynamically adjust the data transfer rate, and under the appropriate threshold level choose a different level of emission. At the same time the background noise threshold changes according to changes, even in the case of large background noise, you can also get a better call quality. In addition, TDMA with a hard handover, the user can clearly feel the call interruption, the user-intensive, dense urban base station, this discontinuity is particularly evident in such areas as will occur every 2 to 4 minutes time transfer case. The CDMA system, Frequency planning simple user distinguished by different code sequences, so the same CDMA carrier can be used in the adjacent district, network planning flexibility, expansion simple. While the CDMA system frequency planning simple, but there are CDMA PN short code system planning, and planning compared to short code PN frequency planning is not necessarily easier. Overall, the planning of CDMA is not simple. On the contrary, is more complex than the GSM system. CDMA system with low cost of network building has a large capacity, low working frequencies than GSM, so in planning CDMA, CDMA GSM station spacing are generally more sparse. So you can build a better network cost savings. Green Technology System network average transmitted power mW maximum transmit power of GSM 125 2 W CDMA 2 mW 200 mW can be seen from the above data is the GSM mobile phone CDMA average power of 2 / 125 CDMA phone more green. Low power spectral density as the key technology for CDMA spread spectrum technology, it expanded the power spectrum is very wide, so power is very low, the benefits are twofold: one to prevent interference with other channels; 2 to prevent interference with other channels. Technical Features 1. CDMA is a spread spectrum communication, spread spectrum communication he has the following characteristics: (1) anti-jamming ability. This is the basic characteristics of spread spectrum communications, all communication can not
CDMA mobile phone posters
match. (2) broadband transmission, anti-fading ability. (3) The use of broadband transmission, the channel transmission power ratio of the useful signal interference signal power is much lower, so if hidden in the noise signal; the power density is low, then, is conducive to signal hidden. (4) the relevance of using spreading code to obtain the user's information, anti-interception capability. (5) multiple users to receive and transmit. 2. In spread spectrum CDMA communication system, the use of new technology has some key new features: (1) diversity with a variety of ways. In addition to traditional space diversity outside. As broadband transmission is frequency diversity played a role, while the base station and mobile station using a RAKE receiver technology, the equivalent of time diversity effect. (2) uses voice activation technology, and technology sectors. CDMA system capacity because of disruption directly related to activation and use of voice technology sector to reduce interference, increase the capacity of the whole system. (3) using a mobile station assisted soft handoff. It can be achieved through the switch seamlessly to ensure the continuity of the call, reducing the likelihood of dropped calls. Switch region in the mobile station received by multiple base station diversity signals can reduce their transmit power, thereby reducing the interference of the surrounding base stations, which together help to improve the way back capacity and coverage. (4) using a power control technology, which reduces the transmission power leveling. (5) has a soft capacity features. Traffic peak in the frame error rate to increase by increasing the number of channels can be used. When a light load of neighboring cells when a heavy, heavy load by reducing the pilot area can transmit power so that the edge of the area intensity of the user due to insufficient pilot to switch to the adjacent cell, so that the burden-sharing. (6) compatibility. Much bandwidth as CDMA, the power distribution in a broad spectrum, if the power density is low, the interference of narrow-band analog systems is small, so the two can coexist. The good compatibility. (7) CDMA high frequency of usage, no frequency planning, which is a feature of CDMA. (8) CDMA QCELP efficient speech coding. Voice coding technology is the digital communication an important issue. QCELP vector quantization code table is to use the difference signal, and according to the degree of voice-activated to produce a variable output rate signal. This encoding is considered to be the most efficient coding techniques to ensure good voice quality in the premise, greatly improving the capacity of the system. This vocoder has 8kbit / S and 13kbit / S sequence of the two rates. 8kbit / S sequences from 1.2kbit / s to 9.6kbit / s variable, 13kbit / S sequences from 1.8kbt / s to 14.4kbt / S variable. Recently, there came a 8kbit/sEVRC encoder, also has 8kbit / s vocoder features large capacity, voice quality has improved significantly. What is a CDMA mobile phone CDMA is Code-DivisionMultipleAccess abbreviation, full name of Code Division Multiple Access, is being used in commerce in recent years, a digital interface technology, it has a high utilization rate, low power consumption mobile phone. CDMA mobile phone is Web-based mobile communication terminal, and now mainland China for the CDMA telecommunications operator China Telecom. Advantages of CDMA mobile phones and

phone compared to, CDMA mobile phone has the following advantages: First, CDMA mobile phones can be said to be truly green cell phone, it is the minimum transmission power (2mw), but we are now using GSM mobile phone (power to 125mw) 1 / 60,cheap chi straighteners, even lower than the radiation power generated by the TV screen; Second, CDMA mobile phones using advanced switching technology - soft switch technology (ie, switching is to continue after a good break), making CDMA phones calls can be comparable with fixed telephone, GSM mobile phone and no dropped phenomenon; Third, the use of CDMA networks, operators reduced investment, which reduced tariffs for the CDMA handset space reserved; four, due to adopt in order to expand the frequency A communication-based modulation and multiple access communication, and its capacity 10 times higher than the simulation, about 4 times more than GSM networks; five, more importantly, the CDMA-based broadband video applications in mobile communications makes it possible , so that the phone calls and send text from the only information service to the narrow bandwidth multimedia applications. Classification of mobile communication technology has a variety of mobile communication system classification. For example, by the nature of the signal points, can be divided into analog, digital; by modulation points, can be divided into frequency modulation, phase modulation, amplitude modulation; by multiple connection points, can be divided into: frequency division multiple access (FDMA), time division multiple access (TDMA), Code Division Multiple Access (CDMA). China Unicom, China Mobile uses GSM mobile telephone network used in FDMA and TDMA is a combination of two ways. Simulation of GSM mobile phones than there are great advantages, however, the spectrum efficiency in the simulation system is only 3 times, capacity is limited; the voice quality is difficult to achieve the level of fixed line telephone; TDMA terminal access only to the highest rate of 9.6kbit / s; TDMA system without soft switching function, and are easily dropped calls, affecting service quality. Therefore, TDMA cellular mobile communication is not the best of modern wireless access, and CDMA multiple access technology is completely suited to modern mobile communication network required for high-capacity, high-quality, integrated services, soft switching, is being more and more operators and users of all ages. Currently, the CDMA business of China Unicom. However, starting from October 1, 2008 Transfer of Unicom's CDMA business from China Telecom. GSM and CDMA mobile phone radiation on the issue known as CDMA (IS-95) system used in fast reverse power control, soft switch, voice activation technology, and IS-95 specification for mobile maximum transmit power limit, so that CDMA phones radiation power in the communication process is very small and the However, some recent reports on the (unit mass of the human body absorbs RF power) is roughly the same. What mobile phone GSM CDMA mobile phones and who radiated power difference in small or large who, in order to draw an objective comparison of actual results from the CDMA technology, a world-renowned authority of well-known companies and a domestic GSM network optimization company engineering and technical personnel in 2001 In early December along the Second Ring Road, Beijing, CDMA and GSM across the board for a mobile phone network transmit power is a test. The results show that the second ring road in the average transmitted power of CDMA handsets 2.4 dBm (1.72mW), GSM phone average transmitted power 28.9dBm (773 mW), taking into account only one-eighth of GSM mobile phone launch time, GSM mobile phone equivalent in time can be reduced to average power 19.85dBm (96.63mW). Thus see, CDMA mobile phones, the average transmit power is equivalent to GSM mobile phone in time of the average transmit power is equivalent to 1.78%. CDMA and GSM mobile phone system to transmit power requirements compared to our first look at CDMA and GSM technical specifications required for mobile transmission power. Now generally
CDMA mobile phone
900MHz band used by GSM mobile phones maximum transmit power of 2W (33dBm), 1800MHz band maximum transmit power of 1W (30dBm), while regulatory requirements, and 1800 for the GSM900 band, the communication process phone were not lower than the minimum transmission power 5dBm and 0dBm. CDMA IS-95A specification on the maximum transmit power requirements for mobile 0.2W ~ 1W (23dBm ~ 30dBm), the current network the phone is actually the maximum allowed transmit power is 23dBm (0.2W), regulate the minimum transmit power of CDMA mobile phones did not ask? In the actual communication process, at some point a place, phone transmitter power depends on the actual environment, the system requirements on the communication quality, voice activation and other factors, in fact, depending on the system link budget. In the usual network design and planning, for basically the same frame error rate requirements, GSM mobile phone system requirements to reach the base station signal carrier to interference ratio is usually about 9dB, the CDMA system uses spread spectrum technology, spread spectrum coding gain on the full rate The gain is 21dB, (for other low-rate coding gain greater), so the signal before despreading carrier to interference ratio requirements equivalent is less than-14dB! (CDMA systems are usually the signal to despreading about the value of 7dB .) Let us now compare the GSM and CDMA mobile transmit power set to take the initial value and power control mechanisms. Phone communication with the system can be divided into two stages, first access phase, the second is traffic communication phase. For GSM systems, mobile phones did not enter in the random access stage-specific pattern before, there is no power control, to ensure access to success, the phone to the maximum allowed power transmission system (usually the largest mobile phone transmit power). In the allocation of dedicated channel (SDCCH or TCH), the phone will be adjusted according to the instructions the phone base station transmit power adjustment step is typically 2dB. Adjust the frequency of 60ms time. For the CDMA system, the random access mode, the phone's base station according to the received signal level is estimated that a smaller value as the initial transmitting power mobile phone, send the first Access Probe, if within the prescribed time did not get the base station response message, the phone will increase the transmission power, sending a second Access Probe, if within the prescribed time the response has not been the base station information, the phone will further increase the transmission power. This process is repeated until the response received by the base station or to reach the maximum number of attempts to set up. During the call state, the base station every 1.25ms to the mobile phone sends a power control command information, command cell phone transmission power increase or decrease in steps of 1dB. It can be seen from the above comparison, taking into account other unique technologies CDMA system, such as soft switches, RAKE receiver,chi iron, multipath diversity of the role of strong forward error correction algorithm improvement budget uplink, CDMA transmission power system for mobile phones GSM system requirements than the requirements of mobile emission power is much smaller. The GSM mobile phone in the access process to the largest power transmission, power control during a call is slow, so the phone to power the larger the probability of launch. The CDMA mobile phone a unique mechanism for random access and fast reverse power control, can maintain the average power and phone at a lower level. The qualitative analysis of the actual measurement in the following conclusion has been verified. Road test test description and analysis of drive test results of experiments carried out CDMA and GSM mobile phone communication in the actual transmission power during the test. CDMA phones and GSM test mobile phone test also dial 1861, the car radio to adjust to the proper volume, analog two-way conversation. Speed of about 40km. Sampling once every 480ms GSM phone, CDMA mobile phones for every 20ms sampling time. Test results are measured: CDMA mobile phone for the average power of linear 2.4dBm (1.72 mW), the maximum power (23dBm, 0.2 W) probability of emission 0.2%; GSM mobile phone average transmitted power of 28.9dBm linear (773 mW), the maximum power (2 watts W) 21.8% probability of launch. It is noteworthy that the present district of Beijing, Beijing Mobile GSM network is quite mature, smaller distance between the base station, GSM phones can lower power transmission, and CDMA networks in the development stage, the network optimized for the requirements of CDMA mobile phones will be more fired power small. Mobile phone safety radiation standards and emission power of mobile phone radiation on human observation and research is still ongoing among the large number of conflicting foreign study is not yet comprehensive scientific conclusions. Current international (including U.S. FCC, NCRP, Europe CENEIEC) standard widely used SAR values (SPECIFIC ABSORPTION RATE), which refers to the human body absorbs RF power per unit mass. (Formula omitted) near the phone when people call the brain (without headphones), mobile phone radiation from the antenna and the human brain is typically less than 15cm. The human brain in the near-field antenna radiation, due to the complexity of the organizational structure of the human body, theoretically the body antenna radiation power and the relationship between the field distribution is very difficult. However, according to electromagnetic theory, one thing is for sure, the antenna structure and the relative position of mobile phones and the human body under certain circumstances, the larger the antenna output power in the electric field strength of the human body to form the higher power RF radiation absorbed by the body the greater the . SAR is an important measurement of the value of the current method is the use of human tissue equivalent model, using the probe to measure RF radiation in the human body by the actual field strength values. More stringent requirements on the SAR is the FCC standard, 30MHz-15GHz band standards recommended two types of radiation: 1. Under the control of radiation limits: 0.4mw / g (human average), peak 8mw / g (for any 1 g of human organizations on average), the average time of 6 minutes; 2. Non-controlled radiation limit 0.08mw / g (human average), peak 1.6mw / g (1 g of human tissue for any average), the average time of 30 minutes. Mobile phone radiation can not control the RF sources belonging to the non-controlling radiation. Specifically, the current mobile phone SAR tests are conducted the results are on the phone to the maximum emission
CDMA mobile phone
power and rate of movement of the whole case to get. Maximum transmit power of CDMA handsets 0.2W, GSM mobile maximum transmit power of 2W, but the GSM mobile phone only in 1 / 8 of the time launch, the SAR value measured is the average of a longer period of time, therefore, GSM and CDMA mobile phone SAR values in this case is similar is not surprising. We can not in this extreme case, CDMA phones and GSM phones SAR value is quite arbitrary and that the actual communication process in CDMA phones and GSM mobile phone radiation are similar. Because in practice the communication process, GSM phones and CDMA phones are not always to the maximum power transmission, in particular, CDMA mobile phones at full speed, the maximum power transmission are rare. From the front drive test statistical results, GSM mobile phones to high-power far greater than the probability of launch CDMA mobile phone the probability of high-power transmitter, CDMA mobile phones, the average transmit power is far less than the maximum transmit power CDMA phones, it is far smaller GSM mobile phone in the average transmit power, therefore, the actual communication process in the CDMA mobile phone radiation on the human body will be much lower than the actual SAR value of the nominal SAR value of the CDMA mobile phone, GSM mobile phones are also much lower than the actual SAR value. On the other hand, objectively speaking, the widely used SAR standards may not be fully reflected the impact of mobile phone radiation on the human body. Because the standards are based on electromagnetic radiation on the human body developed thermal effects. In fact, electromagnetic waves, especially low-frequency pulse electromagnetic radiation on the human body non-thermal effects are also increasingly a cause for concern, GSM mobile phone launch low-frequency electromagnetic pulse has affected the sophisticated medical equipment, proper use of hearing-aid device, whether it is harmful to human body , has not been determined. GSM mobile phone in order to avoid these shortcomings, the third generation mobile communication system terminal equipment will launch CDMA mobile phones are the same as a continuous pulse of radio waves instead of radio waves. The CDMA and GSM, CDMA and GSM technology system for mobile phone transmission power requirements, and take the initial value of the fixed transmit power and the power control mechanism is different in the actual communication process, CDMA mobile phones, the average transmit power is far below the GSM mobile phone the average transmitted power. Measurement confirmed that the existing network, CDMA mobile phone GSM mobile phones than the average power and a small transmitter power of 500 times, taking into account only one-eighth of GSM mobile phone launch time, at the same time, CDMA GSM mobile phone radiation than the radiation energy Little more than 60 times the energy. Theoretically CDMA mobile phone GSM mobile phone radiation is smaller than 2 orders of magnitude, but because only the Qualcomm CDMA chips (USA) exclusive production, but its production processes and other causes of CDMA mobile phone GSM mobile phone radiation up to more than 2 orders of magnitude less than , at most an order of magnitude. Mobile phone radiation safety standard SAR value is the maximum power transmission in the mobile phone cases come, in this case, the GSM phones and CDMA phones SAR value rather is completely normal. The CDMA mobile phone communications during the actual average transmitted power is much smaller than the maximum transmit power of CDMA phones, GSM phones are also much smaller than the average transmitted power, so the actual CDMA mobile phone radiation on the human body is far less than the maximum transmit power of mobile phones under the SAR values, but also in the process of using low frequency radio waves are not radiated, CDMA mobile phone is truly communication system, the system of giving each user their own specific address code. Address each other between the quasi-orthogonal codes, thus in time, space and frequency can overlap; will be required to send certain information and data signal bandwidth, the bandwidth is much larger than the signal bandwidth with a pseudo-random code modulation, so that the bandwidth of the original data signal is extended, the receiving side to the opposite process, for despreading, enhanced anti-jamming capability. CDMA system is self-interference system. CDMA system time system to zero: Definitions June 1, 1980 12:00:00 pm sharp start time for the system. Long code of zero bias and short code in the initial state at this time while all the base stations will be every couple seconds, GPS time, start time (or in this place after a multiple of 80ms) as the PN code offset 0 (cycle 80 / 3 ms) the initial state, that is, just before the output of a ) as the long code sequence m the initial state (before this happens to output a different non-synchronous CDMA network users are not completely orthogonal spreading sequences, which led to multiple access interference; the use of the same carrier frequency, many users share a channel, has a strong signal of weak signal inhibited, resulting in near - far CDMA system using power control technology to solve the 0.030MHz * No. +825.000 MHz downlink carrier frequency: carrier frequency = 0.030MHz * No. +870.000 MHz carrier frequency number contained in the uplink channel number (MHz) Downlink (MHz) 7 283 833.49 878.49 6 242 832.26 877.26 5 201 831.03 876.03 4 160 829.80 874.80 3 119 828.57 873.57 2 78 827.34 872.34 1 37 826.11 871.11 CDMA network operators to replace the June 3, 2008 China Unicom and China Telecom to c net sales reached a framework agreement to jointly safeguard the interests of affected services and . 2008 National Day, cdma family will become a member of China Telecom, China Unicom in mobile communications and mobile with two operators to keep pace. China Unicom's CDMA network business and technology from October 1, 2008 officially transferred to China Telecom. CDMA-related Q & A - Q: CDMA through rate why high A: The people who have experience of the Internet, looking for less time online, this mesh-plug less, it is easy to turn. Cell phones the same way. CDMA interference from the military system, there is a bandwidth, CDMA system is the GSM system capacity of 4 to 5 times, mesh plug a significant decrease naturally through rate high. - Q: Why CDMA cell phone is almost no noise A: CDMA uses advanced digital voice encoding techniques, and using multiple receivers simultaneously receiving signals in different directions. If you listen to a few people talk about different aspects of one thing, comprehensive, you'll understand more about the whole picture, and also omitted a number of unrelated content. - Q: Why is not easily dropped calls A: We know that the protection of the base station is a phone call, when you move to the edge of the coverage of base stations, base station should automatically CDMA system, switching the base station coverage is the before disconnecting the original base station, so the phone will not call drop protection. - Q: Why is it called the small means that the battery life of the phone long, played a protective effect on the environment, it was called the - Q: Why is difficult to eavesdrop on conversations: To eavesdrop your call, you must code to find your site. But your code is a pseudo-random code address, and a total of 4.4 trillion kinds of possible permutations, therefore, to crack the password or eavesdrop on conversations content is too difficult. Q: What are the functions A: six: three simultaneous calls; to display phone number; to then automatically go to your pre-designated phone, pager or mobile phone (unconditional call forwarding); will come when you call, then automatically Go to your pre-designated phone, pager or mobile phone (Busy Call Forwarding); you access to within 30 seconds if you do not automatically go to your pre-designated phone, pager or mobile phone (No Answer Call Forwarding); respectively, then the two parties to call (call waiting). - Q: Which phone to call A: can dial local calls, domestic long-distance fixed-line telephone, city, GSM, China GSM mobile phone. - Q: CDMA can pass the world Answer: Yes, now Tianyi China Telecom has launched an international card business, there is no CDMA network to the country before going abroad can apply for international cards, to support China Telecom's CDMA network in use, and other countries regional CDMA network or GSM networks. . - Q: What 的 CDMA mobile phone market brand A: CDMA mobile phone brands available in the market is currently small, international brands are Samsung, LG, Motorola, Nokia also has a few standard models of CDMA mobile phones, domestic brands are Huawei, ZTE,chi turbo flat iron, Cool,CHI Pink Dazzle Flat Iron, Hisense, day language and other brands. CDMA and CDMA2000 1X difference As for CDMA, one began to build the network is the IS-95 and then upgrade to CDMA2000 1X, and then to the now started EVDO, is CDMA2000 1X upgrade to CDMA2000 1x EVDO, like mobile Unicom's G network from the GSM EDGE to GPRS and then, like, but compared to GSM, CDMA has many advantages! For example, less radiation is one of the biggest advantages of this, this phone is more healthy, and GSM radiation too! And IS-95 and then upgrade to CDMA2000 1X CDMA2000 1X EVDO (ie 1X and EVDO exist two networks), in the RF part is completely compatible with the base station does not need to re-build. Difference: 1, technically, CDMA2000 1X by spreading rate SR1, the former refers to the channel and reverse channel are used chip rate 1.2288Mbit / s single-carrier direct sequence Spread Spectrum method. So it can be easily and IS-95 (A / B) backward compatibility, to achieve a smooth transition. CDMA2000 1X reverse the use of coherent demodulation and fast forward power control, transmit diversity, Turbo coding and other new technologies, the introduction of packet-switched network elements to support mobile IP services. 2, the volume, in the same conditions, the Mandarin sound business, the capacity of roughly CDMA (IS-95) system twice. 3, the rate on, CDMA2000 1X mobile Internet per second transfer rate up to 144Kb, more than 10 times the existing CDMA products. 4, version, CDMA is the IS-95, belonging to 2G technology, CDMA2000 1X is an upgraded version of CDMA (also CMDA2000 the first stage), is the radio of 2.5G technology open source project GNU Radio GNU Radio is free software development tool kit. It provides operation and signal processing module, it can be easily produced by low-cost radio frequency (RF) hardware and general-purpose microprocessors implement software defined radio. The kit is widely used in amateur, academic institutions and commercial organizations to study and build wireless communication system. The main application of GNU Radio is written in Python programming language. But the core of the signal processing module is C + + floating-point operations in a microprocessor with built on. Thus, developers can quickly build a simple real-time, high-capacity wireless communications systems. Although its main function is not a simulator, GNU Radio frequency RF hardware components in the absence of the situation under the support of pre-storage and (signal generator) to generate the data signal processing algorithm. OSSIE OSSIE (Open Source SCA Implementation Embedded), is the Wireless @ Virginia Tech contributed to the open source community of software-defined radio (SDR) to explore. Its main purpose is used for software defined radio and wireless communications technology R & D and teaching. This package contains the JTRS Software Communications Architecture-based (SCA) core framework of the SDR, the rapid development of SDR waveform processing components and tools, libraries of prefabricated components and signal processing. But also with the Naval Postgraduate School to develop laboratory exercises for free with a group practice, teaching and training for the use of SDR. OSSIE as the same may be used GNU Radio Universal Software Radio Platform (Universal Software Radio Peripheral - USRP). CDMA in the distribution network of distribution network line fault indicator means such as a knife switch in the switch or segment of the fault indicator to install equipment on the installation of remote communication acquisition devices, gathering fault indicator signal whether the flip of the remote signals, and the signal is transmitted to the main station. Side of the computer in the master drawing lines on the diagram, and fault signals visually displayed in the graph. (For example, such as right

right picture shows the way fault indicator diagram. The figure dashed CDMA and other communication channels, the white box that was no fault indicator flip, gray squares indicate occurrence of fault indicators Flip, the master control unit can determine this information failure between the switch BW5 and BW6 area. entries Atlas Atlas more references 1
CDMA mobile phone

http: / / www.1818wz.com/html/news/2009/0307/4527.html
Further reading: 1
GNU Radio Chinese community http://gnuradio.microembedded.com/chinese
2
OSSIE Chinese Wiki http://ossie.microembedded.com/
Open Category: technology, cell phones, communications, CDMA, broadband wireless access I have to perfect the