| 摘要 |
In a system for seismic exploration, a narrow passband channel of relatively-slow transmission speed is used to transmit commands from a control station to one or more remote signal acquisition devices to initiate acquisition and processing of echo signals generated by triggering of a seismic signal generator at a selected reference time. To permit use of the slow speed transmission channel for transmitting commands without delay in the recording of the echo signals, a first command to initiate processing and recording of received signals is transmitted to the acquisition devices prior to the selected reference time by an amount of time at least equal to the transmission time of the narrow passband channel. This first command also initiates in each acquisition device the counting of signal samples which are being recorded at a predetermined rate. A second command is transmitted at the selected reference time and upon receipt of this command, the count of signal samples is latched and a number is subtracted from this count based on the transmission time of the narrow passband channel to identify the signal samples which were processed and recorded beginning at the selected reference time. |
