DE1591481A1 - Frequency synthesizer - Google Patents

Description

D-1919

Sanders Associates, Inc,

95 Canal Street

Nashua, New / Hampshire, U.S.A.

Frequency synthesizer

The prior invention relates to a frequency synthesizer, with which it is possible to quickly use a wide frequency range in discrete frequency steps an electronic switch without causing significant switching distortion at the output. Of the Frequency synthesizer delivers the nominal frequency instantly and can be built for any desired resolution.

A frequency synthesizer is a device for selective / on Combining a plurality of input frequencies derived v / at a common source to form a to generate ftusgangssignal that is within a given Frequency range is adjustable. Operating the frequency synthesizer includes switching one of a Set input frequencies to another until the correct one starting frequency has been reached. Such synthesizers j offer many different uses. For example, they can be used as control generators with changeable Frequency and used as tuning oscillators for receivers. They can also be used wherever programmable frequencies are required. In this way

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you can use them to generate encrypted frequency versctVie.)) quaint in particularly secure transmission of communications equipment be used.

Has some kind of tunable frequency generator a continuously adjustable output and can therefore ideally be set to any desired frequency within their work area can be set. However, it has only limited accuracy because it is analog Measurement methods or time-consuming measurement technology are required to determine the set frequency at any time to be able to.

The second type of tunable frequency generator, which is considerably more accurate, generates the output frequency in certain individual steps. The accuracy comes from the fact that the output frequency is from a Number of fixed and stable input frequencies in the range Frequency synthesis is generated. However, this type of tunable frequency generator has hitherto been a fact suffered that gradual transition from one frequency to another unwanted egg oscillations and distortions at the output signal. The present invention is concerned with the second type of tunable Frequency generators. It eliminates the above-mentioned transients in the output signal through appropriate selection the switching time from one output frequency to another.

The invention is ..lie object of the invention To create a tunable frequency synthesizer whose output signal is changed in certain individual steps and that only a minimum of switching distortion '*

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. 3 - J 'I' ^!

contains. The erfindungsgemSsse synthesizer has a linear tuning range and the Ausgangsfre- '■ provides frequency instantaneously and with high accuracy. He loading! there is a high tuning speed with a fine frequency resolution at the same time.

Wit the invention is also a method for * Tuning of a frequency synthesizer created with the switching distortion at the output of the synthesizer! be limited to a minimum.

The invention "is described below with reference to the drawing".

1 shows a block diagram of the invention adjustable frequency synthesizer and

Fig. 2 shows a table, sometimes the frequency resolution and tuning speeds for different multi-level Contains synthesizers that are in accordance with this Invention are possible.

In principle, the synthesizer according to the invention conducts a spectrum of individual frequencies as harmonics

from a basic frequency * It switches between these i

i. Frequencies around to get the output frequency range.

The switching from one frequency to the other is controlled by the same fundamental frequency source so that the switching process takes place when the two signals have the same instantaneous phase and amplitude. The easiest way to meet this condition is if the Scolding process takes place when the signals cross zero. Such a type of constant control of the switching process eliminates phase jumps and phase discontinuities and

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BATH

has minimal energy loss throughout the switching time. Through this the shares of inclusion processes in the exit 3 of the synthesizer is greatly reduced.

The basic unit of the synthesizer preferably comprises a decade system with a number of stages. Each step represents an identifying digit in the frequency of the synthesizer output signal, and the number of the steps determines its frequency resolution. The output frequency of the synthesizer is changed by t that one goes from one harmonic of the fundamental frequency to another switches in one or more stages of the synthesizer, as already stated above.

j As Fig. 1 of the drawing shows, the syn-

thetisierungs a main oscillator 10 with a frequency A ^, wherein the main oscillator generates a sinusoidal output signal •. The output signal of the main oscillator is fed to a spectrum generator 12 which generates a multiplicity of output frequencies which run in harmony with the fundamental frequency. Specifically, the spectrum generator 12 supplies the output frequencies (n - 1) CO + 0, (n - 1) ώ + Διύ, (η - 1) ci + 2Δο3 «·· (η - 1) at terminals 0 ... n u) + (η - 1) Δω, where ω is a harmonic of Δω .

The spectrum generator contains a harmonic generator, e.g. 8. A pulse generator, which is sampled by the main oscillator 10, to which a number of η filters are connected which are matched to the individual output frequencies of the generator. Uereifrker _v *

included in order to achieve a usable signal level **

^r at the generator output. '"',.

009811/0832 bad original *

For the sake of explanation, a decadic system is shown with η = 10, so that the spectrum generator 12 has ten separate output terminals 0 ... 9 which deliver ten separate frequencies, ie 9u + 0, 9ω + Λω, 96J + 2Aw ... 9w + 9Δ «. These ten signals are all synchronized with the same main oscillator 10, and all have experienced the same phase delay in the spectrum generator 12.

The tooth output signals of the spectrum generator 12 and one or more similar switching stages are supplied, which are listed in general form at S ₂ , S ₁ and S _Q in the three-stage system shown. In each stage a switch 16 receives the signals from the spectrum generator 12 and supplies a signal selected therefrom to an icical stage 1B. The frequency selected by each switch 16 is given by ti - (n - 1 ) td + m _Ώ Δ & * ujobei m is a number where 0 ... 9 refers to the position of the associated switch 16, i.e. h, to the respective output terminal of the spectrum generator 12, which was selected by the switch. In the synthesizer shown, the subscript means a »number from 0 .- .. 2", each one of the stages. ^ ». .Ej ₂

denotes «Thus in step S ₂ the switch % '$' ^V. ^ selected frequency in the decadal system given by

In each wiping stage 18 the selected frequency is mixed with another additional frequency, and the sum of these two frequencies is selected at the output of the wiping stage : ■

Thus, in the first stage Sg, the selected frequency Wo "** ■ * · the frequency (0, which is supplied by a generator 20 is mixed. The generator 20 is also sampled by the main oscillator 10. The output signal of the fish stage 1B in stage S ₂ , which appears at point 22, contains the sum of the two input frequencies, ie 100 + -1Ti ₂ Aa) This signal is supplied via a frequency divider 24 to the next stage S _{1 of} the synthesizer The decadic system represented by 10. Thus, the frequency cd + m ₂ A <3/10 is at the output of the frequency divider 24 in the stage S _2.

The output signal of the first stage S _{2 of} the synthesizer uiird in the mixer 18 of stage S ₁ with the frequency t). χ 9 (A + nuAb) combined that of the spec-. strand generator 12 selected by switch 16 at this stage. At the output of the mixing stage 18 of the second stage, which appears at point 26, is therefore the Frequency 1OtO + rn ^ ca + mjZkd / io · As before, this signal is also fed to a frequency divider 24 in order to divide it by 10, thus the output frequency of the frequency divider 24 of the stage S ₁ *) + m ^ ö / 10 + .n ^ At ^ iOO runs.

ίη the last stage S _n "ird the frequency i ^ j * 9 (j + Rt _n Ao, which is selected from the Schelter 16 of this stage and / urde mixed in a mixer 18 with the previously ermähnten Aueganjssignal the step _S1. The output signal the fflischatufe 18 of the last level, which appears at point 28, • reads «omit>

; 8AP ORIGINAL '· /' ^, | ^ |;

This is the representation of the output frequency in decimal digits, with the first, second and third characterizing digits referring to n ^ »m ^ bztu. m ^ refer, with the itelTun-jen of the switches 16 in the stages S ₂ IS ₁ and Sq match.

In the general case containing ρ steps, the output frequency is given by

nc) 4 ΓΠβΔϋ + πι.Δω + mJkvi + '

m _n - ρ

Thus, with each additional stage, the resolution of the output frequency at terminal 28 is increased by the factor η

The synthesizer shown is equipped with an automatic frequency stepping system that controls the Synthesis over an entire output frequency range votes. Each of the switches 16 is provided for this purpose.

Zugsuieise designed as an electronic switch, the is controlled by a counter 30 in the same stage. In detail, each counter counts from 0 ... 9, and the position of each switch 16 depends on the position of the associated counter. Is the content of a Counter for example 3, then the one controlled by it leads Switch 16 in the output terminal 3 of the spectrum generator 12 lying frequency to the wiper stage 18 connected to the switch.

The counter 30 in stage S ₂ counts the pulses coming from a frequency divider 32, the input signal of which is the output signal of the main oscillator 10. A gate 34,

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which is located between the frequency divider 32 and the counter 30 of the stage S _2, is controlled by a control source 36. In the synthesizer shown, a variable delay line 38 is provided between the gate 34 and the counter 30 of the stage S _{2 in} order to facilitate a synchronization of the switching pulses with the harmonically derived input signals supplied to _{the stage S 2.}

When the synthesizer starts working, it is assumed that all counters 30 are set to zero, so that m ₂ , m * and m _{Q are} equal to zero in the three-stage decadic system shown. The output frequency that appears at terminal 28 is 10tJ. If the gate 34 is then opened in order to allow pulses to _{pass through to the counter 30 of stage S 2} , the counting cycle begins in this counter. During this process, the switch 16 in stage S ₂ gradually passes through the successive terminals 0 ... 9 of the spectrum generator 12. As a result, the output frequency of the system, which appears at terminal ZB , advances in small steps to <A, h , over 10ti «10d +% n ¥ r. 10 οΛ + ???. 10t ·) + "ryHft" · 30 has reached the value 9, the first counter, it is by the next pulse from the frequency divider 32: reset tuf Hull ι simultaneously a pulse 8Λ 4 # is discharged n counter 30 of the next stage S ₁ Da. · applying this "pulse to the counter 30 of stage S, causes the switch 16 of this stage, the mixer 18 of this stage with the terminal 1 of the spectrum Generatore 12 to connect · the · training *» '*' output frequency at terminal 28 " becomes 10 + A ^. '% * \'

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BATH ORIGINAL

The counter 30 of the stage S ₂ continues to count the pulses from the frequency divider 32, so that the switch 16 in the same stage the ten positions of the spectrum generator; tors 12 passes through. The output frequency of the synthesizer continues to progress in steps of -r ^ r, that is, 1OeO + j ^ -, 10 * 3 + ^ i ₊ UJ £ _{f 10o +} ΔΑ. +

- · ι 3ed8smal, uienn the counter 30 in stage S ₂ the

if it reaches 9, the next im- ^!

puls the counter 30 of the following stage S ₁ , one place

'I add to its content, whereby a similar setting of the switch 16 in stage S ₁ iuird. Similar _; The same applies to the counter 30 of stage S-. Every time it reaches 9, the next pulse causes it to be reset to zero and a pulse is passed on to counter 30 in the last stage S _n . This causes the switch 16 in the stage S _Q »to switch to the next output terminal of the filter matrix 14. Further pulses from the frequency divider 32 switch the synthesizer!

then in steps of γ ^ · tueicer until the output frequency the allied 1OiO + + · reached at terminal 28. The next pulse sets the output frequency of the synthesizer back to the initial value of 1OtO.

The content of the counter 30 can be fed to a display device 40 which displays the content and thus registers the output frequency of the synthesizer. In the system shown, the first stage S ₂ results in the last and the last stage Sp the first characterizing digit of the frequency display dBs display device 40. Hear the pulses coming from the frequency divider 32 at the command of the control

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source 36, the output frequency at the terminal 28 remains at a certain value, which is displayed by the display device 4G until the pulses from the frequency divider 32 start again.

As has already been stated above, it is desirable that when switching over the individual switches from one terminal of the spectrum generator 12 to the next, only minimal switching processes occur. According to the invention, this is achieved in that the switching processes W are synchronized with the sinusoidal output signal of the main oscillator 10.

So uerdsn with over the output signal of the Main oscillator 10 caused keys oes spectrum generator 12 generated output signals in the spectrum generator, which with üem the output signal of the main oscillator 10 are synchronized. Thus 3ind the output signals of the spectrum generator 12 also synchronized with each other. In particular, their zero crossings also run at the same time as those of the signal from the main oscillator 10. Assuming that the Output signals of the spectrum generator 12 within this all are evenly delayed, they find Zero crossings of these signals and that /! the associated Oscillator signals all take place simultaneously.

liiie already described earlier, control the Si ^ - signals from the main oscillator 10 also switch 16 in the various stages of the synthesizer. Through suitable Setting the variable delay line 3Θ can ensure that the pulses from the frequency divider 32, whose input signal is the output signal of the main oscillator -

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tors 10, 4ie switch 16 only then operate when the harmonic components on the Klun.men 0 ... 9 of the spectrum generator 12 have the same instantaneous values of phaso and amplitude. This? does not fire-be achieved most easily at those times as the Nulldurchgän _v e place of the oscillations of the main oscillator 10, ie taking into account the transit times in the spectral generator 12 in the frequency divider 32, in the delay line 3G -and- in the counter 30. Of course, Nulldurchgsnge üer output signals of the spectrum generator 12 also take place simultaneously with zero throughputs of harmonics of the fundamental frequency Δ & . In addition, the condition of the same phase and amplitude can also be achieved at points other than the zero crossings, if the relative phase and amplitude axis of the output signal b of the spectrum generator 12 are set accordingly.

Thus, there are no rapid phase jumps or amplitude changes at the outputs of the switches 16 when they switch between the output terminals of the spectrum generator 12. In this Ueise be Linschwingvor- etc. ♦ - ■ · ■
gonge on dan outputs of the switches to a minimum ■ -. * ■ '■>'. ■■■. ' *

which results in a far-reaching reduction in the inconvenience of the entire synthesizer

In the general case, a synthesizer can hit ρ levels with a speed of & $ - self-clocking. The frequency resolution of such a synthesizer can? ».). ·. 4f4 expressed «earth. For example, you can use the remaining synthesizer in the case of oiner

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1691481

Frequency of the main oscillator 10 of 100 kHz and at three Steps (p = 2) its tuning range in 1 kHz steps

walk through. The synthesizer then has a tuning

1 π η ιϊι η 7

closeness of

sec

2 shows a table with the tuning speeds in Hz / sec and the frequency resolutions for various combinations of frequencies of the main oscillator, gate 10 and number of stages. This shows that the synthesizer enables high tuning speeds and that the frequency resolution can be considerably increased by increasing the number of stages in the synthesizer. t

Can be so improved Frequenzsynthetieator with self, active consultation has an output signal that} quickly in small, diskreten'Frequenzschritten einge- · provides. By suitable selection of the shift. ' time from one output frequency to the other can go through ^! the switching-related transient processes in the output signal are largely reduced and grounded, so that very precise frequencies can be generated very quickly with the synthesizer according to the invention.

Although the present drawing shows an arrangement with an automatically running frequency range * ' is set, it goes without saying that the counters 30 and Schal- '■

ter 16 can also be connected together so that the

also non-consecutive frequencies ζυ «βη» ΐ «βηβ <: ητ> Ι |« η,

ie any two outputs of the Spektru »eo, enere.tore 12. * \ _t <

Muf this lifeise the synthesizer can also there # ing # i # Ut ^ j-

and / or programmable frequency sequences are required mt & tfat) * ^A. * * R

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Claims (1)

Claims 1. Method for generating a spectrum of successive frequencies, characterized in that a multitude of harmonic and synchronous to one Fundamental frequency signal lying frequency signals is derived that these frequencies successively on an output circuit are switched, and-since this switching process is synchronized with the fundamental frequency signal, so that switching between two signals takes place when both have the same instantaneous values of phase and Possess amplitude. 2. Frequency synthesizer, characterized by a signal generator for generating at least two harmoniously lying signals, an output circuit, switches between the signal generator and the Output circuit and are able to switch the signals through one after the other to the output circuit, and means that Synchronize the switching of the switch with the two signals so that the switching process takes place when both Signals have the same instantaneous phase and amplitude own. 3. Frequency synthesizer according to claim 2, characterized in that a sequence of such switches and one corresponding sequence of frequency changing devices is provided, each switching door between the signal generator and its corresponding ^ frequency changing device * and the means for synchronizing the switching of the control individual switches, and that means are also provided to enable successive frequency change devices 009811A0832 ^ _{0 0R | G1NAL} ; connections with each other, including the output frequency ! each frequency changing device is a function of both the ! Position of their respective switch as well as the output frequency u of the previous frequency changing device. 4. Frequency synthesizer according to claim 3, characterized in that each frequency changing device contains a mixer, at the inputs of which the output frequency of the corresponding switch and the output frequency of the previous frequency changing device, and that all frequency changing devices with the exception of the latter have a frequency divider to divide the Ausyangnfrequenz your wiper before passing on to the to share the next mixer. b. Frequency synthesizer, Q-marked by a signal generator having a number of output terminals; Synchronizing means for controlling the signal generator to generate synchronized and harmonious output signals at the output terminals; a first Switching stage and at least one uieiture switching position that jsiueils a multi-position switch as well as a Frequency changing device included, the switch of each switching stage between the number of output terminals and the frequency changing device of the relevant Switching stage lies; medium to consecutive Frequency changing devices to be connected to one another, dnn that the frequency changing device of the first ' Switching stage occurs first in the sequence and the output signal every frequency changing device every BATH ORIGINAL ' 009811/0832 The lower switching stage is a function of the position d_f -chriltere of the same stage and the Ausganyssiynals of the preceding Frequfjnzr'nderun.jsvorrichtung} and switching means for connecting the synchronizing means to the switch each switching stage, whereby the operation of each switch is synchronized by the synchronizing means with the generation of the harmonious signals. 6. Frequency synthesizer according to claim 5, characterized characterized in that the frequency changing device provided in each u / further stage includes a wiper whose Output frequency is the result of the output terminal frequency signal selected by the switch of the same stage and is the output frequency aJs of the previous frequency restraining device. 7 »Frequency synthesizer according to claim 6, characterized characterized in that a second Siynalqenerator is provided its output signal is an input signal of the mixer represents the first level of support. B. frequency synthesizer according to claim 6, characterized characterized in that each means for interconnecting successive frequency changing devices includes a frequency slider representing the output frequency of each wiper divides before it goes to the mixer of the next stage is fed. 9. Frequency synthesizer according to claim a, characterized characterized in that each frequency divider divides the output frequency of the associated wiper by a number that Number of output terminals in the frequency generator. 009811/0132 bad orig'NAL 10. Frequency synthesizer according to claim 9, characterized in that the frequency generator has ten output terminals. 11. Frequency synthesizer according to claim 5, characterized in that each switching stage has a counter contains, the count of which determines the position of the switch of this stage, also means for connecting the Synchronizing means with the switch of the first stage, and means for connecting the counters to one another, whereby each counter sends a signal to the next counter. "gives, in order to keep its counter reading always u / pus, if the counter behind has run through a counting cycle, 12. Frequency synthesizer according to Anspruöi 11, characterized in that a display device is provided, that is connected to all counters to show their counts 13. Frequency synthesizer according to claim 11, characterized in that the synchronizing means one Frequency divider, a gate located in the input line to the counter of the first stage and means for control of the gate. 14. Frequency synthesizer, characterized by A wrong signal generator with a number of outputs * one Oscillator to control the signal generator to generate a ; To generate a number of synchronized and harmoniously lying signals at the outputs} a number of switching stages, each with a mixer and an m * Switch with a number of switch positions, the z «i- 009811/0832 _BAD or.g.nal .- 17 - see the signal generator and the mixer at the same stage lies; Frequency divider that zduiachen successive Wipers lie to divide the output frequency of each mixer before being fed to the next mixer ufird, whereby the wiper of each switching stage as input signals the output signal of the switch of the same switching stage and the divided output frequency of the previous one Mixer receives; a counter for each switching stage, the counter reading of which corresponds to the switch position of the switch of the same Level determined; means to route signals from the oscillator to the counter of the first stage and its count to move on; and means for interconnecting the counters, whereby each counter sends a signal to the counter of the supplies the next switching stage in order to switch on its counter reading and its corresponding switch as soon as the first-mentioned counter ends a counting cycle, and whereby the switching process in each 'switching stage by the The oscillator is synchronized with the generation of signals at the outputs. 15. Frequency synthesizer, characterized by a first signal generator with ten output terminals} an oscillator for controlling the signal generatora to ten synchronized and harmoniously lying Generate signals at the output terminals; .one place Switching stage and a number of subsequent switching stages with one wiper each and one between the output terminals of the signal generator and the mixer of the same Level switch with ten positions, the ten Output terminals correspond; one Irish ftf n each - 009111 / ifrIiI. BATH ORIGINAL Mixing successive switching stages lying frequency divider, which the output frequency of the previous Wischers divides by ten; a second signal generator connected to the mixer of the first switching stage; a decade counter for each switching stage, the count of which determines the position of the switch of the relevant stage; medium to get signals from the oscillator to the counter of the first To conduct switching stage and to advance its counter reading, this means a frequency divider for dividing the | Frequency of the oscillator included, further a delay device to the pulses from the oscillator with the signals to synchronize at the output terminals, a downstream of the frequency divider the gate and means for the control of the Tores, whereby pulses from the oscillator to the counter of the first stage are controlled uieitergsleiten, with a Speed that is less than that of the first signal generator lowest frequency generated; and means for interconnecting the j counters, thereby making each counter a Forwards the signal from the oscillator to the counter of the next switching stage in order to advance its counter reading, as soon as the first-named counter finishes a counting cycle. ßAD 001111/0832