| 摘要 |
PURPOSE: To provide the spread spectrum signal generation circuit which can be miniaturized without using a digital multiplier. CONSTITUTION: Serial transmission digital data are transformed to parallel data of a prescribed number of symbols by a shift register 1, and this parallel data has the polarity inverted in accordance with a spreading signal pattern by a polarity inverter 2 and is inputted to a waveform generation ROM 3 as address input. Primary modulation waveform obtained by subjecting transmission data to primary modulation and band limitation of one symbol section is preliminarily stored in the waveform generation ROM 3 as a digital signal, and this stored data is read out synchronously with the scan address signal from a scanner 4 with data inputted from the polarity inverter 2 as the address. It is reproduced into an analog signal by a D/A converter 5 and passes a band pass filter 6 to obtain a spread spectrum signal. In distinction from a conventional circuit, it is unnecessary to use a digital multiplier which makes the circuit scale larger. |
