Study Of ADSL's Test Methods Based On DSP Technology

Asymmetrical Digital Subscriber Loop (ADSL) is a prevalence fashion of broadband solutions today. It uses the installed base of copper telephone line as the transmission medium. With the combined use of sophisticated signal modulate methods and the high speed digital signal process technology, it's upstream speed can be 100Kbps to 800Kbps and the downstream delivers from 1Mbps to 8Mbps. As the telephone networks are installed at large, ADSL almost needn't carryout any new lines. It is very suite to eliminate "the last mile" bottleneck of today's broadband solutions. For recent years, ADSL has world widely employed and widely used in many aspects such as VOD, remote medical treatment and e-shopping etc.But we noticed that the traditional telephone networks are designed for the transmission of low frequency signals, and the ADSL's frequency rang is from 0 to 1.104MHz, so we must confront the signal attenuation, the loop line noise impairments, the crosstalk interferences, the bridge tap reflections and the RF disturbances problems and many other problems when transmitting the ADSL signals one the telephone networks. A series of test must be carried out before ADSL provide services. With the ADSL service developing, the demand of ADSL test instruments increases rapidly, and the market space is very expanse. At present, there many questions in test methods of the ADSL test instruments while the prices are very high, and more, the manufactures are mostly foreign companies. It is necessary to develop a general-purpose and cheap kind of ADSL test instruments.Based on the lucubration of ADSL's transmission characters, the author concluded the main noise sources on the loop and their influences to the ADSL's transmission performance. According to the review and comparison of today's ADSL test instruments, the author finds the lack of the traditional test methods and indicates that easy to use, versatility and extensible are crucial aspects to design an ADSL test instruments. The author also bring up a new method, the adaptive test method which can be used to test the ADSL's transmission characters on the whole band dynamically. Simulations on MATLB are carried out to test the algorithm's validity. After a thorough study on the DSP Platforms, the author designed the instrument based primarily on TMS320C6000 DSP Platforms of Texas Instrument Incorporation, the TMS320C6203B processor. The entity frame of hardware and software are planned.Surrounding the actualization of the algorithm, the author accomplished the main hardware and software design of the DSP target. The upper computer software has also been designed.There six chapters in this thesis. The first chapter concluded the characters of today's ADSL test instruments and their lacks. The second chapter introduced the ADSL transmission's basic knowledge and the main influence factors of the transmitting speed surrounding ADSL's test. The third chapter brought up the adaptive algorithm and simulations on MATLAB were carried out. The fourth chapter introduced the hardware design based on TMS320C6203B.The fifth chapter introduced the software design and the critical algorithm's realization. A conclusion was carried out in the sixth chapter.