CDMA is " spread spectrum (頻譜) " technology, which means that it spreads the information contained in a particular signal of interest over a much greater bandwidth (帶寬) than the original signal.

    When implemented (實(shí)現(xiàn)) in a cellular telephone system, CDMA offers numerous benefits to the cellular operators and their subscribers (訂戶). Following is an overview of CDMA benefits:

    1. Improved call quality, with better and more consistent sound.

    2. Simplified system planning through the use of the same frequency in every sector of every cell.

    3. Increased talk time for portables.

    4. Bandwidth on demand.

    Compared with GSM ( Global System for Mobile communication ), which was developed mainly in Europe, the CDMA system matured (成熟) later and has better efficiency, low radiation, high voice quality and ability to adopt third-generation communications technology.

    China, Indonesia, Japan, South Korea and now India will make up the major market for CDMA technology in addition to the United States, the Republic of Korea, Japan and Australia to  ensure that CDMA users can receive phone calls from overseas.

 56. Which of the following statements is TRUE?

     A. CDMA has a clearer and higher sound than GSM.

     B. You will not hear a better and more consistent sound if you don't use CDMA.

     C. CDMA has the ability to adopt third-generation communications technology.

     D. The original signal cannot satisfy the demand for bandwidth.

 57. Which of the following statements is NOT true?

     A. CDMA has low radiation and high voice quality.

     B. CDMA can help you to have a long-time talk.

     C. China and some Asian countries will have a large market for CDMA technology in future.

      D. It's much simpler to use CDMA than GSM.

58. What is the main idea of this passage?

     A. Compared with GSM, CDMA has more benefits.

     B. Some information on CDMA and its advantages.

     C. CDMA will probably take the place of GSM some day.

D. CDMA is more effective and healthy.

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