This article will propose corresponding solutions to the problems encountered in mobile phone wireless communication. With the country issuing 3G license operation permits, China has entered the 3G era. Faced with this new opportunity and challenge, both communication operators and mobile phone manufacturers have begun a new round of fierce competition. Mobile phones have problems with frequency band control, communication quality detection, and signal size control during communication. The absolute advantage of the spectrum analyzer called by RF engineers as "RF multimeter" in spectrum analysis can help solve these problems. The OBW occupied bandwidth function can detect whether the energy of interest is within a specific bandwidth. By setting the power ratio to 99%, it is measured that the signal contains 99% of the energy within the bandwidth of 1.396666MHz. For the above measurements, the DSA1030A also provides user-friendly operation measurement results storage and measurement settings loading. The user can save the measurement settings locally and load them directly when the next measurement. This can reduce the operating time, reduce the probability of operating errors, and improve measurement efficiency. You can also save the measurement settings to the U disk and load them into other spectrum analyzers to facilitate the migration of the measurement. The user can edit the measurement settings in the laboratory in advance and save them to the U disk, and then directly transplant them to the instrument on the measurement site. The measurement results can also be saved from the instrument to the computer through the U disk for later analysis and processing or as report data. The spectrum analyzer can conveniently and quickly manage and monitor the wireless communication frequency band of the mobile phone, monitor the signal strength in each channel during communication, and detect the signal of the communication process signal. White Boards,Movable Writing Board,Movable Writing Rack,Metal Movable Writing Board Feat Top International(China) CO.,LTD , https://www.nbfeattop.com
Question 1: Each communication operator must control its own communication frequency band
ITU has strictly defined the frequency bands for communications. Industrial and scientific communications, fixed and mobile services, satellite communications and other communications methods must be carried out in their respective frequency bands. Even in the same frequency band, communications for various services are also strict. Definition. If the frequency band bandwidth of the communication exceeds its allocated range, it will not only interfere with other communications but also affect its own communication energy. Therefore, the communication bandwidth and signal energy concentration need to be tested.
Question 2: Need to ensure the quality of communication signals
During mobile phone wireless communication, various noises are mixed in the channel, and the noise causes the quality of the communication signal to deteriorate, so the signal-to-noise ratio of the communication channel needs to be measured.
Question 3: There will be breathing effect and near-far effect in the mobile phone wireless communication system
In a wireless communication system, when the interference signal in a cell is strong, the actual effective coverage area of ​​the base station will be reduced; when the interference signal in a cell is weak, the actual effective coverage area of ​​the base station will become larger, which is Breathing effect. In short, the breathing effect appears as the coverage radius shrinks as the number of users increases. Since mobile phone users are randomly distributed in a cell and change frequently, the same mobile phone user may sometimes be at the edge of the cell and sometimes close to the base station. If the transmission power of the mobile phone is designed according to the maximum communication distance, when the mobile phone is close to the base station, there must be excess power and harmful electromagnetic radiation is formed, which is the near-far effect. The method to solve this problem is to adjust the transmission power of the mobile phone in real time according to the difference in communication distance, that is, power control. This requires real-time monitoring of the size of the communication signal.
The spectrum analyzer can solve the above three problems well. Let's take the DSA1030A spectrum analyzer from RIGOL as an example to introduce how to perform the test in detail. The frequency range of DSA1030A spectrum analyzer is 9kHz ～ 3GHz, the average noise level DANL is -148dBm, the typical value of phase noise is -88dBc / Hz @ (offset 10kHz), the full amplitude accuracy is less than 1.0dB, which can help solve To the problem. At the same time, the DSA1030A spectrum analyzer also has a rich one-key measurement function, which can respond to various complex needs. The following uses a TD-SCDMA signal as an example to illustrate the role of a spectrum analyzer.
For problem one and problem two, ACP adjacent channel power measurement and OBW occupied bandwidth measurement in the DSA1030A spectrum analyzer can be used to solve. Leading power measurement can measure the power of the main channel, the power of the previous channel and the latter channel, and the signal-to-noise ratio measurement between the main channel and the upper and lower adjacent channels. The lower left of Figure 1 is the measurement result. The user can flexibly set the bandwidth of the main channel, the bandwidth of the adjacent channel, and the distance between the main channel and the adjacent channel according to specific needs. The lower right of Figure 1 is the measurement setting value. By using the function of leading power measurement, the energy size of the channel communication and the signal-to-noise ratio of the communication can be clearly measured. It can be drawn from Figure 1 that the main channel energy is -10.69dBm and is basically concentrated in the 1.6MHz bandwidth, which meets the requirement that the bandwidth of each carrier of the TD-SCDMA signal is 1.6MHz. The adjacent channel suppression is -51.32dB and -51.66dB, which can meet the general needs. 
Figure 1 Using ACP to measure the energy and signal-to-noise ratio of a signal
For problem three, the Pass / Fail function in the DSA1030A spectrum analyzer can be used to solve it. The user edits the two standard traces in advance according to the actual needs, that is, the upper and lower limits of the measurement. After this function is turned on, the statistical pass rate will be measured for the measurement results. When the measurement fails, it will automatically stop the measurement and view the frequency and amplitude of the measurement failure. As shown in Figure 3, the Pass / Fail function is used to monitor the size of the signal. 
Figure 2 OBW measurement of signal energy concentration 
Figure 3 Use the Pass / Fail function to monitor the signal size
Figure 4 Save and load Pass / Fail settings