| 摘要 |
1,124,680. Data transmission systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. 25 May, 1966 [2 June, 1965], No. 23453/66. Heading H4P. Binary data is transmitted by a frequency shift system in which the two frequencies have a frequency difference equal to the data bit rate, an integral number of cycles per bit interval, and zero phase at the bit transition points. Various forms of transmitter are described, Figs. 2, 4, and 6 (none shown), each of which produces a single side-band signal in which the 1 and 0 bits are respectively represented by f 1 and f 2 and in which frequencies f 1 and f 2 are present continuously but are phase displaced from the 1 and 0 frequencies. The continuous frequencies are separated at the receiver from the 1 and 0 frequencies and applied to a product modulator which develops the difference frequency. This is at bit frequency and controls a bit-rate clock which samples the data signal for regeneration of the original data. |
