FM is FM stereo with the best sound quality and can only receive local signals. Moreover, FM means that the frequency of high-frequency carrier is not a constant, but a modulation mode that changes with the modulation signal in a certain range, and its amplitude is a constant. So the signal is relatively stable.
AM is medium wave, followed by sound quality, and can receive medium and long-range signals. AM refers to amplitude modulation, which is an electrical signal that changes from sound level to amplitude. It is far away and greatly influenced by weather factors, so it is suitable for inter-provincial radio broadcasting.
Therefore, in order to ensure the stability of CET-4 and CET-6 listening, the school will adopt FM, and the frequency will be announced before the exam, so that everyone can listen in advance and ensure the smooth exam.
The role of CET-4 and CET-6;
1. Because the CET-4 and CET-6 adopt the normal grading system, the results published after each exam contain a lot of information, which becomes the dynamic basis for the decision-making of education administrative departments at all levels, and also provides feedback information for schools to take measures to improve teaching quality according to their own school's actual situation.
2. CET-4 and CET-6 have formed a complete system from proposition, examination, examination organization, statistical analysis to result release, which is a large-scale examination carefully organized in strict accordance with the quality requirements of standardized examinations.
3. College English test has been recognized by the society and has become one of the standards for recruiting college graduates by personnel departments at all levels, which has produced certain social benefits. ?
Refer to the above? Baidu encyclopedia-CET-4 and CET-6