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高频,在无线电波中指3～30 MHz的频率。在工业上,称10000 Hz以上为高频。中频,在无线电波中指300～3000 kHz的频率。在工业上,50～10000 Hz为中频。此外,在超外差收音机中,把射频信号变为预定频率的信号,以便放大。这个预定频率也叫中频,其数值随射频段和工作方式的不同而异。低频,在无线电波中指30～300 kHz的频率。在电子电路中,一般指低于射频或中频的频率。其频率范围与声频相近,因此声频放大器也叫低频放大器。在工业上,低于50 Hz的为低频。工频,工业上使用的交流电频率。我国规定为50Hz。视频,电视或雷达由图象转换成电信号的频率。自0～数MHz。
High frequency, in the radio wave refers to the frequency of 3 ~ 30 MHz. In industry, it is called high frequency above 10000 Hz. Medium frequency, in the radio wave refers to the frequency of 300 ~ 3000 kHz. In the industry, 50 ~ 10000 Hz for the IF. In addition, in superheterodyne radios, the RF signal is changed to a signal of a predetermined frequency for amplification. This predetermined frequency is also called intermediate frequency, its value varies with the radio frequency band and work methods. Low frequency, in the radio wave refers to the frequency of 30 ~ 300 kHz. In electronic circuits, generally lower than the RF or IF frequency. The frequency range and audio similar, so the audio amplifier is also called low-frequency amplifier. In the industry, frequencies below 50 Hz are low frequencies. Power frequency, the commercial use of the AC frequency. My country is 50Hz. Frequency of video, television or radar conversion from images to electrical signals. From 0 to several MHz.