Continuous tuning control particularly adapted for use in variable frequency receivers and generators

• US 4,266,295 A
• Filed: 12/18/1978
• Issued: 05/05/1981
• Est. Priority Date: 12/18/1978
• Status: Expired due to Term

• Current Assignee: Henry M. Bach Jr
• Original Assignee: Henry M. Bach Jr
• Inventors: Bach, Henry M. Jr.
• Primary Examiner(s): NG, JIN FAY
• Application Number:
  US05/970,269
• Time in Patent Office: 869 Days
• Field of Search: 334/14, 334/15, 334/48, 331/30, 331/31, 331/36 C, 455/170, 455/173, 455/176, 455/177, 455/178, 455/192, 455/197, 455/261, 455/262, 455/158, 325/453, 325/455, 325/458-460, 325/462-465, 325/468, 325/420, 325/421, 325/422, 325/469, 325/470, 325/432, 325/433
• US Class Current: 455/158.2
• CPC Class Codes: H03J 3/185 with varactors, i.e. voltage variable reactive diodes
• CPC Class Codes: H03J 5/24 with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection

Abstract

This disclosure describes a continuous tuning arrangement for a variable frequency response circuit of the type covering a relatively wide frequency range. Many techniques for accommodating a wide frequency range are known and include synthesizers, waveform generators and so on which employ various coarse tuning controls or devices for band selection. A synthesizer is described which employs a continuous tuning means enabling one to continuously tune the circuit from a first frequency to a second frequency or from said second frequency to said first in a rapid manner, whereby continuous tuning is afforded without the necessity of returning the tuning control to a start position each time a new frequency is selected by the coarse tuning control. The continuous tuning means provided according to this disclosure incorporates a variable reactance device in which the magnitude of the control voltage is alternated according to a change from the first frequency to the second frequency as accommodated by said coarse control. In another embodiment, continuous tuning is provided again from a low to a higher frequency by means of a differential capacitor.

Claims

1. A variable frequency generator, comprising:

(a) a tuning control means including a controllable oscillator means coupled thereto for providing an output frequency which is continuous varied from a first to a second frequency by moving said control means from a first limit position to a second limit position according to a given control value specifying the magnitude of said output frequency within a given range,

(b) actuatable means coupled to said tuning control means and operative when actuated to abruptly alter said control value to enable continuous tuning of said oscillator means from either said first to said second frequency or from said second to said first frequency by moving said tuning control means between the same limits to therefore vary said magnitude of said output frequency always within said given range, whereby said output frequency may be continuously varied by said tuning control means either from the first to the second frequency or from said second to said first frequency consecutively without either the necessity of continuously varying said output frequency from said second frequency to said first frequency or from said first to said second frequency.

2. The variable frequency generator according to claim 1 wherein said oscillator means includes a frequency synthesizer operative to select any one of a plurality of frequencies by means of a series of selector switches operative to control a tunable frequency source, each of said switches indicative of a digit of said frequency as selected.

3. In apparatus for providing a range of signals over a relatively wide frequency band by selecting one of a plurality of said signals in said band by means of a tunable frequency source, the combination therewith of apparatus for varying said selected frequency within a smaller predetermined range, comprising:

(a) a controllable variable reactance means capable of providing a continuous variable output reactance which varies from a first value indicative of a first frequency to a second value indicative of a second frequency,

(b) selector means coupled to said variable reactance means to provide a reactance indicative of one of said values and relatively independent of the previous value of the reactance of said variable reactance device.

(c) means coupling said variable reactance device to said tunable frequency source to enable variation of said selected frequency within said smaller predetermined band whereby said reactance as varied will always cause the frequency as defined by said band to be controlled between said first and second values as determined solely by said selector means to cause said selected frequency to be continuously varied by said reactance means from said first frequency to said second frequency consecutively without the necessity of continuously varying said output frequency from said second frequency to said first frequency.

4. The apparatus according to claim 3 wherein said tunable frequency source is coupled to a plurality of selector switches at least one of which is moveably operative to select at least one digit indicative of said selected frequency.

5. The apparatus according to claim 4 wherein said variable reactance means includes a variable reactance device capable of being continuously tuned from said first value to said second value by means of a variable source of potential coupled to said reactance device and operative to vary said reactance from said first value to said second value by application thereto of said potential varying from a first level to a second level, and control means responsive to the movement of said at least one of said selector switches including switching means coupled to said at least one selector switch and operative to alter said source of potential to cause said first level to be first applied to said reactance device when said selector switch is moved to a higher frequency position, whereby said reactance device will always vary said frequency from a lower to a higher value within said band.

6. The apparatus according to claim 4 wherein said relatively wide frequency band encompasses the range between 50 KHz to 30 MHz as employed in radio reception.

7. The apparatus according to claim 4 further comprising a potentiometer having a first and second terminal with a variable control arm capable of being varied between said first and second terminals, said variable control arm coupled to said varactor diode, a first potential source for providing a potential indicative of said first level, and a second potential source for providing a potential indicative of said second level, switching means having a first input coupled to said first potential source and a second input coupled to said second potential source, said switching means having an output terminal coupled to at least one of said terminals of said potentiometer, and means responsive to the movement of said selector switch to cause said switching means to provide either said first or second level to said potentiometer terminal to therefore cause said varactor to vary said capacitance, always to provide a higher frequency during one position of said selector switch when said arm is moved towards said coupled potentiometer terminal, and during another position of said selector switch when said arm is moved away from said coupled terminal.

8. The apparatus according to claim 3 wherein said variable reactance means includes a differential capacitor of the type having a first section capable of providing a reactance from a high to a low value and a second section capable of providing a reactance from a high to a low value, and means responsive to said selector means to selectively couple said first or second section to said tunable frequency source.

9. The apparatus according to claim 3 wherein said variable reactance device is a varactor diode of the type exhibiting a change in junction capacitance according to the application thereto of a varying potential.

10. In a radio receiver of the type employing a first local oscillator for application of an output signal to a mixer to provide a first IF frequency, said first local oscillator being of the type tunable over a relatively wide band of frequencies indicative of a broadcast band by means of programmable switches capable of being selected to specify the frequency of said oscillator within a predetermined number of significant places according to the settings of said switches, said receiver including a second mixer responsive to said first IF and a second source of oscillations to provide at an output a second IF signal, the combination therewith of apparatus for varying the frequency of said second source of oscillations within a smaller predetermined range indicative of said least significant places of said first oscillator frequency as selected, and to vary said frequency within said range from a lower to a higher value, comprising:

(a) a tunable variable reactance means coupled to said second oscillator and capable of providing a continuous variable output reactance which varies from a first value indicative of a low frequency to a second value indicative of a higher frequency to therefore vary said second oscillator within said range from a low to a high frequency,

(b) means responsive to a directional movement of at least one of said programmable selector switches indicative of said least significant places of said specified frequency to cause said reactance to provide said first value when the direction of said selector switch movement specifies an increase in frequency to thereby allow a user to tune said second oscillator from said low to high frequency relatively independent of the previous tuned condition of said variable reactance means.

11. The apparatus according to claim 10 wherein said variable reactance means includes a varactor diode coupled to said second oscillator and capable of varying the frequency upon application to said varactor of a suitable control voltage.

12. The apparatus according to claim 10 further including a potentiometer having a first and a second terminal and a variable arm movably positioned between said terminals, said arm being coupled to said varactor, switching means responsive to the movement of said at least one selector switch, said switching means coupled to one of said terminals of said potentiometer to provide a first operating potential thereto when said selector switch is in one frequency position to cause said reactance to vary said oscillator frequency from a low to high value when said arm is moved towards said one terminal, and to provide a second operating potential to vary said oscillator frequency again from said low to high value when said arm is moved away from said one terminal when said selector switch is in another frequency position.

13. A variable frequency response circuit for providing a range of signals over a relatively wide frequency band, said circuit including a plurality of switches operative to control a tunable frequency source to enable selection of any one frequency within said band by said switches being set to a value indicative of said frequency, the combination therewith of apparatus for varying said frequency as selected within a predetermined smaller range and always from a lower to a higher value independent of said frequency as selected, comprising:

(a) a tuning control operative to provide a control signal upon movement of the same from a first to a second position,

(b) variable reactance means coupled to said tuning control and operative to provide a variable reactance when said control is moved from said first to said second position manifesting a continuous change in reactance from a first to a second level,

(c) means coupling said variable reactance means to said tunable oscillator to vary said frequency within said predetermined smaller range according to said change in reactance,

(d) switching means responsive to the movement of one of said selector switches and coupled to said tuning control to alter said control signal when said selector switch is moved to a higher frequency position to cause said tuning control as operative to vary said reactance from said first to said second level upon movement of said control from said second to said first position and according to the direction of movement of said selector switch, whereby said tuning control is always operative to vary the frequency as selected within said range from a lower to a higher value.

14. In apparatus for providing a range of signals over a relatively wide frequency band by selecting one of a plurality of said signals in said band by means of a plurality of selector switches operative to control a tunable oscillator, each of said switches indicative of a digit of said frequency as selected, said apparatus including a tuning control operative to increase the frequency of said oscillator in a first direction and to decrease the frequency in a second direction to cause said frequency as controlled to undesirably remain at a higher frequency when one of said selector switches is moved to a higher frequency selector position, whereby said tuning control has to be returned to a start position indicative of a lower frequency to permit tuning to a higher frequency in said first direction, the combination therewith of apparatus for varying said selected frequency by said tuning control within a smaller predetermined band from a lower to a higher value without returning said control to a start position, comprising:

controllable reactance means coupled to said tuning control and having an output terminal coupled to said oscillator, said reactance means responsive to the operation of said selector switch to said higher frequency position, for varying the frequency of said oscillator from a low to a higher frequency during a first position of said selector switch by controlling said reactance by operating said tuning control in said first direction and for varying the frequency of said oscillator also from a low to a higher frequency during a second position of said selector switch by controlling said reactance by operating said tuning control in said second direction, whereby the frequency of said oscillator will always be at a lower frequency when said one selector switch is moved to said higher frequency position to enable tuning of said oscillator from said low to said higher frequency in either of said first or second directions according to the setting of said one selector switch.

15. A method of varying the generated frequency of a variable oscillator comprising the steps of:

(a) continuously moving a tuning control coupled to said oscillator from a first to a second limit to cause said oscillator to vary its output frequency continuously from a first frequency to a second frequency,

(b) abruptly altering a control value for said oscillator to enable tuning from said first to said second frequency by moving said tuning control from said second to said first limit whereby the generated frequency may be varied continuously from said first to said second frequency consecutively without the intermediate step of continuously varying the generated frequency from the second frequency to the first frequency.

16. In combination with a variable frequency generator of the type capable of providing a variable output frequency according to the adjustment of a tuning control apparatus for varying the output frequency within a predetermined range, comprising therewith:

(a) a tuning control means coupled to said generator and operative in a first direction to vary said output frequency from a first low frequency to a second higher frequency manifesting said predetermined range by operating said tuning control continuously from a first limit position to a second limit position, said tuning control means operative in a second direction to vary said output frequency from said second higher frequency to said first low frequency by operating said tuning control from said second to said first limit position,

(b) actuatable control means in circuit with said tuning control means and adapted upon actuation, to enable said tuning control means to reverse directions to therefore vary the output from said second to said first frequency upon movement of said tuning control means continuously from said first limit position to said second limit position and to vary the output from said first to said second frequency continuously from said second limit position to said first limit position, whereby the direction of tuning between said first and second frequencies is altered by said actuatable control means.