The prior art real-time control system for use with an NMR spectrometer is equipped with a timing control system which is called a pulse programmer or pulser. The timing control system acts to control the generation and the phase of RF pulses required for the NMR spectrometer.
FIG. 1 shows the prior art real-time control system for use with an NMR spectrometer. This control system includes a control section 1 producing m-channel control signals which are fed to functional units 2a, 2b, etc. via a pulse bus line 3. The control section 1 comprises a controller 4 and a pulser 5, and serves to control the synchronization of the whole system. The pulser 5 stores timing data items t.sub.1, t.sub.2, . . . , t.sub.n for determining the timing at which the system is controlled. The pulsers also store data for controlling the system, hereinafter referred to as the control data. The control data is m-bit data indicating the condition of each channel at every instant or during every period, i.e., indicating whether it is 1 or 1. The controller 4 reads the control data from the pulser 5 according to the timing data and sends m-channel control signals to the bus line 3. The functional unit 2a receives the control signal of channel 1, for example, from the bus line 3 through a multiplexer 6, and controls a gate circuit 7 or other control means included in the NMR spectrometer.
FIG. 2(a) shows one example of the waveform of the control signal of channel 1 supplied to the gate circuit 7. A generator 8 produces an RF carrier as shown in FIG. 2(b). The RF carrier is passed through the gate circuit 7. RF pulses as shown in FIG. 2(c) appear at the output of the gate circuit 7 and are supplied to the NMR probe (not shown).
In the above-described prior art real-time control system for use with an NMR spectrometer, the control signal for enabling and disabling the gate is produced by the pulser 5 and fed via the pulse bus line 3 to the gate circuit 7 in the functional unit 2a. Therefore, if the number of the functional units 2a, 2b, etc. increases, the number of bus lines is increased. Where the number of bus lines is limited, it is only possible to connect functional units corresponding in number to the bus lines.
The gate can be enabled or disabled by one bit of data, or one control signal. Where the system is controlled in a complicated manner, as encountered when the RF frequency assumes various values, plural bits of data are needed. This necessitates the use of plural bus lines. Accordingly, in order to control the system in a more complex manner by the functional units, more bus lines are needed. If the required number of bus lines are not available, then it is inevitable that limitations are imposed on the complex control.
Moreover, the prior art system has the problem that it cannot easily synchronize various components of the system. In particular, in the conventional system, the functional units are controlled by the signals transmitted through the bus lines. Because the control signals pass through the separate lines, the time taken for each control signal to pass from the control section 1 to the functional unit differs among the lines. This problem becomes more serious when the operation speed of the system is increased. Although this problem can be addressed by designing the bus lines to transmit signals up to higher frequencies, this system entails much cost.