| 摘要 |
PURPOSE:To send a double data in one carrier frequency and to attain high speed data transmission by applying MSK modulation to a data of the 1st bit of a transmission data divided for each 2-bit and applying amplitude modulation to the signal in response to the data of the 2nd bit of the transmission data. CONSTITUTION:When a transmission data of NRZ(Non-Return-to-Zero) form whose speed is, e.g., 2400bps is divided by a division circuit 13 for each 2-bit, an MSK(Minimum Shift Keying) modulation circuit uses a carrier frequency 1800Hz to apply MSK modulation when the 1st bit is data '0', and used a carrier frequency 1200Hz to apply MSK modulation when the 1st bit is data '1'. Then the amplitude modulation circuit 15 applies amplitude modulation having a signal from the MSK modulator 14 when the 2nd bit is data '0' and applies amplitude modulation to a signal from the MSK modulator 14 at a multiple of the unity when the 2nd bit is data '1'. An MSK demodulation circuit 19 in a demodulation section demodulates the signal into a reception data thereby demodulating the signal into the received data in 2 bits. Thus, high speed data transmission is attained. |
