| 摘要 |
PURPOSE:To hold a detection time in a short time and in a constant way by changing a reference voltage being the reference of the detection in response to the input level even if the level of the burst of an input signal changes in a burst detection circuit in a system such as a TDMA system transmitting/ receiving the data in burst. CONSTITUTION:The carrier signal of an input burst is detected by diodes Dl, D2 of a detection circuit 1 and its high frequency component is eliminated by an integration device comprising a resistor R1 and a capacitor C1 and its envelope voltage is outputted. The envelope voltage output is inputted to the input terminal 21 of the differential operational amplifier of a comparator 2 as the signal input and it is compared with a reference voltage Ref given to the other input terminal 22. When the level of the input burst signal changes, the voltage of the reference voltage input is changed as shown in waveforms 22a, 22b, then the difference between the waveforms 21a and 22a is nearly equal to the difference between the waveforms 21b and 22b. Thus, the detection time tau is almost the same at any of leading/trailing of the input burst and unchanged.
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