Anordnung zur Frequenzmodulation eines Generators

摘要

1308715 Sweep frequency signal generators SIEMENS AG 18 Dec 1970 [22 Dec 1969] 60351/70 Heading H3R A sweep oscillator comprises a frequency synthesizer with sweep generated by a counter controlled from a pulse generator. Digital frequency synthesizer 1 produces an output frequency f a determined by the inputs on digital control lines E 0 -E 6 which are energized by corresponding pulses from outputs A 0 -A 6 of counter 2: a pulse shaper 16 may be interposed so that successive pulses overlap in time. Counter 2, which may comprise a series cascade of bistable trigger stages with feedback to give a digital output, is driven by pulses 3 from pulse generator 4, via gate 5. If the frequency f a is to be effected between upper and lower limits the corresponding start and stop numbers are set on counter 2, starting being effected by a control signal A s on line 10 from programme controller 9. Stopping is effected by means of digital comparator 6 which receives a stop number signal from programme controller 9 which is compared with the outputs A 0 -A 6 and when equality is reached produces a stop signal E s which closes gate 5. For wobbulator action a control device 7 is provided which derives a signal from stop command signal E s to close gate circuit 5 via line 51, also emits a signal A s setting counter 2 back to the predetermined start number, and then produces a delayed signal via line 51 to re-open the gate 5. The repetition frequency f z of pulses 3 produced by the pulse generator 4 may be set via a control line 8 from programme controller 9: f z may be varied in accordance with a chosen time function. Control device 7 can also be used to drive display devices or printers: e.g. the start signal can trigger the x-deflection of a printer or oscilloscope via output line 13, the stop signal being emitted via line 14 to terminate the deflection. The sweeping speed may be changed during the progress of a sweep by means of a control signal derived from line 81, this control signal being also applied to the control device 7 to produce on line 15 a corresponding control signal switching over the deflection speeds in a display device or printer. The x-deflection for a display device or printer may alternatively be derived from the outputs A 0 -A 6 or inputs E 0 -E 6 via a digital to analogue converter.