1　前言现行收视率调查通常是通过请观众写问卷的方式来获取资料,显然,这种方式有许多弊端,资料误差很大。近来,出现了一些结合有线电视频道变换器的用户收视资料收集仪,基本原理见图1。每当用户选择收看电视节目时,其收看的频道、时间等信息被记录在IC卡上。定期取回IC卡,将数 1 Introduction The prevailing ratings survey is usually by asking the audience to write the questionnaire to obtain information, it is clear that this approach has many drawbacks, data errors. Recently, there have been a number of subscriber ratings data collectors incorporating cable TV channel changers. The basic principle is shown in FIG. 1. Whenever the user chooses to watch the television program, the channel, time and other information watched on the IC card is recorded. Regularly retrieve the IC card, the number