| 摘要 |
PURPOSE:To reduce the spread of a spectrum and to allow a signal to rise and fall sharply by providing switches for generating burstlike signals in front of and behind a filter for limiting the band width of a transmitted signal, and making the switching time different for those switches. CONSTITUTION:For TDMA communication, the output of a transmitting local oscillator 5 is modulated at an orthogonal modulator 6 by two input signals (a) and (b), and supplied to the 1st switch SW8. Its output is supplied to the 2nd switch SW9 through a BPF7 for limiting the band width of a transmitted signal. Those SWs 8 and 9 turn on and off repeatedly by switching control signals (c) and (d) synchronizing with transmitted burstlike signals, and the output of the SW9 is regarded as a transmission output. The switching timing of the signal (c) is equal to the time T of the burstlike signals to be transmitted, and the signal (d) rises 1/2t (t; time width of one bit) earlier and falls 1/2t slower than the signal (c). Consequently, the spread of a spectrum on a frequency axis is reduced, and the rise and fall of the signal are made sharp as much as possible to improve communication efficiency without disturbance to other communication. |
