| 摘要 |
An electronic range expander, such as for use on a sonar system, which has a rotating disc lamp or a rectilinear pen record, of the travel time, expressed as a certain distance from the transducer to an object and back again. The received signal is sampled periodically, and these samples are stored in a random access memory, in addresses which are determined by binary numbers successively outputted from a binary counter, which is stepped in accordance with a clock signal. As the binary number representing an address in the memory is incremented, the sampled value of received signal is stored in the corresponding address. The command to write in the memory is repeated at a selected number of clock counts. Intermediate the commands to write into the memory, the command is given to read the signal stored in a selected address and to send it to a latch and to the output display or printer of the sonar apparatus. During the period in which the readout of data from memory takes place, a buffer in each of the leads from the counter to the memory causes the binary number from the counter to be shifted to the right one bit, and therefore the address read is 1/2 that of the last write address. Thus the stored values in the memory are read at 1/2 the rate at which they are written, which thereby causes 2/1 expansion of the time scale.
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