MXPA96000066A - Reduction of interference of oscillators in electronic equipment - Google Patents

Abstract

The present invention relates to an electronic apparatus that includes an interfering part that generates, from a first signal, an interference signal having a spectral component within a bandwidth of a receiver, a method for reducing interference within the width of the receiver band comprising the step of: angularly modulating the first signal with a noiseless, deterministic modulation signal, where an angularly modulated interference signal having lateral modulation bands that are outside the width of the receiver band and a reduced carrier wave amplitude is generated by the interference part

Description

REDUCTION OF OSCILLATOR INTERFERENCE ON ELECTRONIC EQUIPMENT INVENTOR: KARL B. LINDALL, a Swedish citizen, residing at Mjdlnarstigen 4, 18146, Lidingd, Sweden, assigns all his rights to ERICSSON INC. , a company duly organized and constituted in accordance with the Laws of the State of Delaware, United States of America, with address on One Triangle Drive, P.O. Box 13969, Research Triangle Park, North Carolina 27709, United States of America, for the invention described below.

REDUCTION OF OSCILLATOR INTERFERENCE IN ELECTRONIC EQUIPMENT BACKGROUND OF THE INVENTION The present invention relates to oscillators and clocks in electronic equipment, and especially to methods and apparatuses for reducing unwanted electromagnetic emissions of such oscillators and clocks. Modern electronic equipment depends to a large extent on the use of clocks and oscillators. Examples of such equipment are personal computers, household appliances (in which now generally includes microprocessors and digital circuits), telephone exchanges, radio equipment (including cell phones), and appliances that have a power supply that uses switching power. , by way of example. One characteristic of oscillators and clocks is the production of an unwanted emission of electromagnetic energy that can create problems not only for other nearby equipment but also for nearby circuits within the same equipment as oscillators and clocks. For example, within a radio receiver, an oscillator in a neighboring circuit may create interference in the radio receiver due to the emission of unwanted signals at a frequency in which the receiver is sensitive to interference, such as the reception channel expected or at an intermediate frequency in a superheterodyne receiver. (As used in this specification, the word "interference" can refer to an interference either radiated or conducted.) In many radio designs, all oscillator frequencies used internally are derived from a single, high-precision reference oscillator that can produce interference in fundamental, harmonic and subharmonic frequencies of the oscillator. It may be impractical or impossible to de-tune the oscillator to avoid this interference because the frequency error of the oscillator is too large for this purpose. This is often the case in cell radios and associated base stations as well as in many other radio designs. A known solution to the problem of reducing the harmonic interference generated by a clock signal in a radio transceiver is presented in US Patent Application 5,263,055, issued to Cahill on November 16, 1993. This patent shows the use of a Frequency dispersion signal generator and a signal modulator. The frequency dispersion signal is produced by means of a pseudo-random noise generator and has the properties of white noise. The signal modulator modulates the clock signal with the frequency spread signal to produce a modulated clock signal that includes a modulated harmonic frequency component. This results in the power level of a modulated harmonic frequency component that corresponds to the harmonic frequency component that interferes with the filtered signal, to be dispersed over a frequency bandwidth As large as the width of the predetermined frequency band thus causing that the level of potency of the modulated harmonic frequency component within the width of the predetermined frequency band decreases. Japanese Patent Document No. 61-95651, published May 14, 1986, appears to show a system very similar to that of the Cahill patent. In a radio receiver, a reference signal having a center frequency f0, which is used as a synchronization signal within the receiver, is subjected to an angular modulation by a noise signal produced by a modulation source. When the center frequency of the signal to be received is sufficiently greater than the reference signal frequency f0, the frequency spectrum of the nth harmonic that causes the interruption s is widely dispersed and the interference is greatly reduced. A problem with the prior techniques presented both in the Cahill patent document or in the Japanese Patent Document is that the use of a noise signal to disperse the harmonics of the reference signal does not provide the ability to completely eliminate all the side bands within a range of the receiver's band. (In this context, the width of the receiver band refers to the frequency band around an assigned channel frequency, wherein the interference signals may affect the reception when the receiver is tuned to the channel.) In the best of In cases, these sidebands may be attenuated to some extent, the amount of attenuation is equivalent to the ratio between the width of the receiver band and the width of the dispersion band. Another drawback of these systems is the fact that noise generators themselves are difficult to impli- cate, which increases the design and construction cost of the circuit. Similar problems of unwanted emission occur in other types of electronic equipment that contain oscillators and clocks with a defined constant frequency. In such equipment, it is frequently observed that many other signals are derived from the clock or oscillator signal in such a way as to cause an unwanted emission in the form of a linear spectrum covering a large bandwidth. Frequently dominant components are observed in the spectrum emitted in multiples of the clock frequency or multiple subharmonics of the clock frequency. The exact position and amplitude of the components may vary with the state of the equipment, but the dominant lines remain. Due to potential problems of coexistences between several clock-based and oscillator-based systems, such equipment is required to comply with national and international standards regarding electromagnetic compatibility (EMC). These standards define a maximum level of electromagnetic radiation that an electronic device can radiate. Unwanted emissions are measured frequently, in accordance with technical standards, by the use of a superhighway detector with a bandwidth of 120 kHz. A line in the emitted spectrum will provide an output of the detector that corresponds to its amplitude. If several lines are within the width of the detector band, then the output will be approximately the sum of their amplitudes. In electronic circuits the unwanted emission traditionally remains below the minimum limits by means of the careful design of the circuit boards, by means of disconnection and protection, through the use of balanced lines, low power levels, and other principles of well-known design. However, these techniques are often inadequate to reduce unwanted emissions to an acceptable level.

Accordingly, it is desired to provide a method and apparatus that can attenuate the unwanted emission of electromagnetic elec energy by clocks and oscillators at a level that emits interference with other circuits and adjacent equipment. It is also desired to provide a method and apparatus that can attenuate the desired emission of electromagnetic energy by clocks and oscillators to a level that satisfies various national and international standards in regard to such emission. SUMMARY OF THE INVENTION One aspect of the present invention finds application in an electronic apparatus that includes a reference oscillator, and an interfering part that generates an interference signal having a spectral component within a width of the receiver band, the The reference oscillator supplies a reference oscillating signal to the interfering part from which the interference signal is derived from whose reference oscillating signal. According to the invention, the amplitude of the interference signal within the width of the receiver band is reduced by the angular modulation of the reference oscillating signal with a sinusoidal modulation signal whereby the interfering part generates a signal of Angular modulated interference having modulation sidebands that lie outside the width of the receiver band and a component of the reduced carrier wave within the width of the receiver band. In a preferred embodiment of the present invention, the sinusoidal modulated interference signal has a modulation index, ß, which is close to a solution of the equation (J (ß) = 0, where J is a Bessel function of the first kind). A satisfactory value of ß can be a value that sufficiently reduces the carrier wave voltage of the modulated interference signal to a level that produces an acceptable amount of receiver interference. The frequency of the modulation signal is selected such that the modulation sidebands are outside the width of the receiver band. A modulation frequency that exceeds the width of the receiver band will be fulfilled for this purpose when the interfering carrier wave falls within the width of the band. Half the width of the band is sufficient if the carrier wave falls exactly in the center of the width of the band. Angular modulation can be achieved by applying direct frequency modulation to the reference oscillator with the sinusoidal modulation signal to generate a modulated reference signal, and then by applying the modulated reference signal to the interfering part to generate the signal of angular modulated interference having spectral components that lie outside the width of the receiver band. Finally, the angular modulation can be effected by phase modulation of the reference oscillating signal with the sinusoidal modulation signal before it is delivered to the interfering part in such a way that the interfering part generates the angularly modulated interference signal which has the lateral bands of modulation that are outside the width of the band of the receiver. When this latter method is employed, the unmodulated reference oscillation signal may be supplied to a non-interfering part of the electronic apparatus. This is useful when it is desired to supply an unmodulated signal to the non-interfering part. Another aspect of the present invention finds its application in an electronic apparatus that includes an oscillator that generates an interference signal having a spectral interference component within a width of the measurement band. According to the invention, the interference is reduced by the use of a noiseless, deterministic modulation signal, such as for example a sawtooth wave modulation signal, to angularly modulate a clock signal from which derives the interference signal in such a way as to cause the interference signal to become an angularly modulated interference signal having a reduced spectral component within the width of the measurement band, the reduced spectral component being much smaller than the interfering spectral component. The angular modulation step of a clock signal from which an interference signal is derived may comprise the steps of applying a direct frequency modulation to a reference clock that generates the reference clock signal, and then supplying the modulated frequency clock signal to an emitting generator circuit within the electronic apparatus instead of the clock signal, the emitting generator circuit being responsible for the generation of the interference signal, alternatively, the angular modulation step of a The clock signal from which the interference signal can be derived can comprise the phase modulation of the clock signal, and then the supply of the clock signal with modulated phase to a transmission generating circuit within the electronic device instead of the clock signal, the emission generator circuit being responsible for the generation of the interference signal. In accordance with one embodiment of this aspect of the invention, a width of the modulation band of the interference signal with angular modulation exceeds the width of the measurement band. In another aspect of the present invention in which a clock circuit generates a combined signal comprising an interference signal in addition to the desired clock signal, the interference can be reduced by an angular modulation of the combined signal in accordance with as described above. BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of the invention will be understood by reading the following detailed description in combination with the drawings in which: Figure 1 is a block diagram of an electronic equipment including a first mode of compliance with a first aspect of the invention; Figures 2a-b are graphical comparisons of emission levels produced by a circuit with and without the use of techniques in accordance with the first aspect of the invention; Figure 3 is a block diagram of an alternative embodiment in accordance with the first aspect of the invention; Figure 4 is a block diagram of electronic equipment including a mode of compliance with a second aspect of the invention; Figures 5a-b are graphical comparisons of emission levels produced by a circuit with and without the use of techniques in accordance with the second aspect of the invention. Figure 6 is a block diagram of another embodiment in accordance with the second aspect of the invention; Figure 7 is a graph of a clock signal that has been modulated by a sawtooth wave according to an embodiment of the present invention; Figures 8a-d are graphs showing empirical test results in which the various techniques of the present invention were applied; and Figure 9 is a diagram of a phase modulator circuit of the prior art. DETAILED DESCRIPTION OF THE PRESENT INVENTION Several aspects of the present invention will now be discussed in various modalities. First, several modalities that can reduce the radio receiver interference of an oscillator will be presented. Then, various embodiments of the invention will be able to attenuate unwanted emissions of a clock or oscillator up to levels that comply with national and international standards regarding such emissions. In all cases, an angular modulation is applied to the oscillator signal to achieve redussion of the unwanted emission.

Referring now to Figure 1, a block diagram of electronic equipment including a first embodiment of the invention is presented. The audio equipment can be, for example, a radio equipment that includes a receiver 101. In this example, it is desired to prevent the interfering part 103, which can be a logical control station, from generating a strong interfering signal 109 at the receiving frequency of the receiver. 101. For this example, the resection frequency will be considered to be 422.4 MHz, and the interfering part 103 employs a 6.4 MHz clock signal that is derived from the reference ossi 105 that oscillates at a frequency of 12.8. MHz. Therefore, there is the potential that the interfering party 103 generates an interfering signal including the 66th. harmonic of the clock frequency. A person are siertss knowledge in the. Matter will recognize that while the reference oscillator 105 and the interfering part 103 may be separate parts, as illustrated, they may alternatively be the same part. That is, it is possible for a reference oscillator to also generate unwanted harmonics that cause interference in a bandwidth of the receiver. However, only for the purpose of illustrating the various features of the present invention, the following comments consider the reference oscillator 105 and the interfering part 103 as separate entities. Regardless of this approach, the principles and techniques set forth herein are applied in the same way in the case where a referensia oscillator itself generates an unwanted interference signal. In accordance with the invention, the interfering signal is greatly attenuated by angular modulation angling to the reference ossiator 105. As shown in Fig. 1, the angular modulation is achieved by means of a modulation of a direct frequency of the oscillator. reference 105, This technique can also be applied in the case in which the reference ossiiador 105 and interfering party 103 are the same party, as mentioned above. Those skilled in the art are well aware of the techniques for modulating the frequency of an ossification and dishasicheses are not described in detail here. The people are certain assumption of the teasy will recognize that the same angular modulation could alternatively be achieved by the phase modulation aplissation at the output of the reference oscillator 105. In both cases, the modulation signal is chosen to be a signal without noise , deterministic (in the case of random signals or pseudo-random signals with white noise characteristics), preferably sinusoidal that produces a modulated signal that has a modulation index that will cause the signal of the frequency of the carrier wave at the resection frequency to be small. The selection of a modulation signal without deterministic noise such as the sine wave instead of a wave having white noise characteristics allows the invention to achieve a greater attenuation within a given bandwidth centered around the frequency of the harmonization. nterferente. This is because the sinusoidal modulation can cause all sidebands to pass out of a given band gap. In somparasión, the use of blast noise as a modulation signal allows only an attenuation equivalent to the recession between the bandwidth of the receiver and the width of the dispersion band. Accordingly, the present invention allows a substantial attenuation to be achieved in a substantially lower modulation by subtracting the correct modulation signal. The sinusoidal modulation signal must be selected in such a way that the modulation rate of the modulated signal is close to the solutions to the equation .1 »(ß) = 0, where ß is the modulation index and Jg is the Bessel function of the first type. For example, in a preferred embodiment, the modulation index, ß, is selected (for example, from a Bessel function table) in such a way as to satisfy the JQ <ratio; > . R "where R is the desired ratio between the reduced voltage level of the carrier wave of the modulated signal and the voltage level of the carrier wave of the unmodulated signal. By way of example, if R = 0.1 (equivalent to a reduction of 20 dB), a value of ß between 2.2 and 2.4 in the interfering frequency is a satisfactory value. People who have certain knowledge of the. The technician will recognize that an aseptable value of R depends on the susceptibility of the partiscular reseptor to the. internship Also, a modulation frequency is selected such that it produces modulation sidebands outside the bandwidth of the receiver. In the example shown in Figure 1, the interfering signal 109 will be redrawn by the use of the odulasiin generator 107 to modulate the output of the reference ossi 105 by the aplissation of a modulation signal having a modulation index of 2.4 at 422.4 MHz, and one. modulation frequency of 60 kHz, which provides lateral bands of modulation outside the bandwidth of the 8 kHz receiver. This attenuation results from the fact that at certain modulation indices, for example in the vicinity of 2.4), the spectral component of the modulated signal at the unmodulated carrier wave frequency disappears. The modulation index at 6.4 MHz is only 2.4 / 66 = 0.0364, which is too small to cause the poor funsionation of the control logic bus (ie, the interfering party 103).

It should be recognized in the previous example that the 60 kHz co or modulation frequency selection is an arbitrary selection. Any frequency higher than the bandwidth of the receiver can be used. For example, in the previous example, a modulation frequency of 8 kHz would also be aseptable. Figure 2a is a GRAFISA illustrating the interfering signal 109 that would result without the modulasión the ossi lator and Figure 2b is a GRAFISA showing Efesto of the modulation technique of the present invention on the interfering signal 109. FASIL body is observed that the strength of the interfering signal in the reception frequency decreased greatly. An alternative embodiment of the invention described above is illustrated in Figure 3. Here, the concern remains that the interference creating party 103 generates an interference signal 109 at the reselection frequency of a receiver 101. However, the electronic equipment also includes a non-interfering part 301 for which it is desired to supply an unmodulated signal direstament? from ossilador 105. Therefore, it is not feasible to directly apply frequency modulation to the reference ossilador 105, To achieve this, the oscillator output 105 is supplied to a phase modulator 303 which receives a signal generator modulasión Modulation 107. In Figure 9 is shown, an example of a conventional sirsui or phase modulator. The people who have some knowledge of the technique conostenes for the phase modulation of a signal and dishasis are not discussed here are more details. Modulasión signal is determined sonformidad are as previously dessrito are relasion Figure 1. The output of phase modulator 303 to the interfering portion 103. This is then supplied sonfigurasión, the clock signals modulated to be supplied only to those parts that create interferent signals. The other parts that do not create interference or that do not tolerate a modulated signal can receive the unmodulated clock signal as shown in the figure. The use of phase modulation, of sonification is shown in Figure 3, it also applies to the case in which the ossilator 103 itself is responsible for the generation of the interfering signal. The phase modulated clock signal can be distributed generally to other parts of the apparatus. In this case, it may be necessary to additionally use generally known design principles to reduce the interference that may emanate between the oscillator 103 and the phase modulator 303. The modalities described above referred to the use of a sine wave as a modulation signal. However, you can also design a little string based on the teachings presented here, but using a noiseless, deterministic, different wave such as a square wave. As taught, for example in P.F. Panther, "Modulation Nsise and Spestral Analysis" (Noise Modulasión and AnAiisis Espestral) 257-260 (MsGraw Hill 1965), incorporated herein by reference, the Fourier series of a modulated carrier wave frequency by a square wave is obtained through (cutting pair of sidebands) By setting ß = 2 in the above equation, one finds that the amplitude of the carrier wave vanishes. In general, a modulation index, ß, must be selected in such a way that it complies with the relation (2 / ?? ß) sin (pß / 2) = R, where R is a predetermined relation between the amplitude of the modulated carrier wave and the amplitude of the unmodulated carrier wave. The exact value of R will depend on the requirements of the specific circuit that is being designed. Using a modulation are sufficiently large causes the sidebands to fall outside the width of the receiver band.

By following, of sonformity are the aspesto described above of the present invention, it is possible to avoid interferences that, in another way, it would be difficult to avoid. Small and compact designs can be achieved at a lower cost and weight, due to the fact that a lower degree of protession and disconnection is required. The related problems are the previously identified interference can be resolved at a later stage in the electronic equipment development system which saves time. Also, not only one frequency is improved but all the frequencies at which the modulation index is sufficiently close, for example 2.4 to provide the desired attenuation of the interference. This aspect is important because the interference that comes from digital circuits often occurs in the form of harmonics of a relatively low clock frequency, which interferes in several channels within the bandwidth of the receiver tuning band. In accordance with a second aspect of the present invention, an angular modulation is applied to a reference clock signal in an electronic equipment to reduce unwanted electromagnetic emissions to levels that allow the astronomy equipment to meet national and international standards in relation to they are such emissions. As previously explained, such standards establish a maximum level of electromagnetic radiation tolerated from a team? Lestropiso. With reference now to the Figure. 4, there is presented an embodiment of the present invention that attacks this problem. Here, the electronic equipment 400 includes an oscillator 401 that provides a clock signal for use by springs 407 that create emission, which generate the interfering signal 409. In the present invention, a phase modulation is applied to the output of ossilator 401 by means of a phase modulator 403. Alternatively, angular modulation can be achieved by the di-lase epilation of frequency modulation to ossilator 401, in the form before dessrita in relasión they are Figure 1. The wave modulated in both sasos is a wave without noise, deterministic and preferably a wave in the shape of a sawtooth that, in this mode, is provided by the modulation wave generator 405. The use of a noise wave signal, deterministic, as For example a sawtooth wave, instead of a white noise signal provides advantages, including the hesho which is simpler to generate the modulation wave. For example, a sawtooth wave can be generated simply by integrating a constant voltage and by periodically resetting the output.

The effectiveness of this design is clear from the hesho that a frequency modulated signal in sawtooth are a large modulation index has a spectrum are components of an almost equal amplitude within the sweep anshura of the modulation frequency. Each spectral component of the modulated signal has a power level that corresponds approximately to the ratio between the sawtooth modulation frequency and the sweep bandwidth. This is because the spectral components are equally spaced at modulation frequency distances within the sweep bandwidth. The number of components within the sweep bandwidth is by sonsiguient? equal to the relasion between the sweep anshura and the modulation frequency. The power of the total signal is essentially equally shared between the components, and each of them has a correspondingly lower potency. This spectrum is shown in Figure 7-11 on page 260 of the aforementioned Panther book which is incorporated herein by reference. If this modulated spectrum is measured, it is a power measurement device that has a bandwidth of B Hz and a modulation frequency greater than B is chosen, only one spectral component is present at the same time within the band width of the potency measurement device anywhere in the modulation spectrum. The measurement device will then show the power of only one of the components and a desired redussion is achieved. When the medi- cation device is a peak potency meter, it is convenient to use a modulation spectrum as a component of constant amplitude within the band gap of the potency medi- cation device. The meter will then never show more than the peak level of each component which is also equal to the average level, since the amplitude is constant. This means that a deterministic modulation is a flat spectrum, as the sawtooth sweep is better for this purpose than a random noise spectrum is an average average espestral potency within the width of the medial band since the noise signal will have a ridge higher than the average value. The peak potentia meter shows a high mA peak potency for noise modulation, which for the sawtooth modulation is a comparable frequency deviation. The effect of a sawtooth wave having a frequency slightly higher than the bandwidth of the medial band is optimal in the sense that it provides a lower peak power in the width of the medial band than other choices. This is because if the frequency is raised then each component will be larger. On the other hand, if fresuepsia is decreased, then several components will fall within the width of the medial band, which will be added to the higher peak potency even when the average power remains the same. Preferably, the frequency of the sawtooth wave is selected within a range of frequency values, the range of frequency values having a low frequency value that is substantially equal to the width of the medial band and a high frequency value that is consistently equal to 1.5 times the bandwidth of the medial band. For the purpose of illustrating the foregoing principles, we consider that a bandwidth of the potentiating device is slightly less than 100 kHz and that a reduction of 10 dB (ie, 10 times) of spectral component levels is desired. this bandwidth. The above-described principles of the present invention are sonic, a sawtooth modulation frequency of 100 kHz can be used. Likewise, the total signal power must be shared among 10 components to provide the desired redussion of power. To reduce these 10 components, the clock signal must be modulated angularly by a sawtooth wave having a sweep resistance of 10 x 100 kHz = 1 MHz. The frequency variation of a modulated clock signal 701 that has been modulated with the wave of Sawtooth saw is presented in Figure 7, The above teachings will now be appended to an example with reference to the cirsuito of Figure 4, If the astronomical equipment 400 is, for example, a personal computer, then the clock frequency can be 66 MHz, We believe you want to avoid interference that occurs around 900 MHz. A 1 MHz frequency sweep of the 900 MHz components requires sweeping the 66 MHz clock signal in (66/900) x 1 MHz = 73.3 kHz. The festivity of this design is illustrated in Figures 5a and 5b. Figure 5a shows a graph of a line spectrum of the interfering signal 409 that would result in general d? the direct aplissation of the exit of ossilador 401 to the entrance of the little chairs 407 that create emissions. It can be seen that the interfering signal 409 in this saso comprises 3 lines 501, 501 ', 501". The first line 501 falls within the bandwidth B_p_tcc-_5 at which an electromagnetic emission measurement must be performed. Without the use of the present invention, the amplitude of the first line 501 exceeds the maximum allowed amplitude Knav established by national and / or international standards.

Somatively, Figure 5b shows the effect of the aplimation of the sawtooth frequency sweep wave modulation to the output of the oscillator 401. Here, the interfering signal 409 includes twelve lines spaced in the frequency spectrum. However, only the third line 503 falls within the band gap B_ Ii-f__ £ c_l5_ in which an electromagnetic emission measurement must be made. The fact that the amplitude of this third line 503 TS lower than the maximum amplitude allowed? EX established by national and / or international standards is important. Accordingly, electronic equipment 400 must meet these requirements. In hesho, by the angular modulation of the modulus at the output of ossilator 401, the lines of the line spectrum are dispersed in such a way that a smaller potency falls within its bandwidth, including the band anhure in which a detector Make your emission measurements. It should be noted that this teasant does not deceive the test method because the test method provides a good measure of the intended interaction. That is, the lower the measured emission, the lower the actual interference created by the emission in the radio receiver that the test method simulates. Another embodiment of the invention will now be described as reference to Figure 6. Here, the electronic equipment 600 comprises digital discrete circuits that include the broadcasting address circuits 609. A clock signal for use by the broadcasting circuits. 609 is derived from the output of a ossilator 601 which can typically be a crystal oscillator having a sinusoidal output. Of sonformity are the present invention, the. output of ossilator 601 is supplied to a phase modulator 603. The modulation signal is derived from a tooth wave generator d? sierra 607 del sual designs are well sonosidos on the part of people are true knowledge in the matter and are not described in more detail here. The output of the sawtooth generator 607 is supplied to the input of an integration filter 605 to ensure that the output of the phase modulator is the same as what would be produced by modulating direstament? The frequency of the oscillator 601 is the output of the sawtooth generator 607. Therefore, this aspect of the present invention provides relatively large attenuations of unwanted emission. This reduces the disconnection and protection costs. The configurations shown in Figures 4 and 6 are very suitable for integration into clock circuits and processors. The empirical test results in which various theses of the present invention are applied will now be referred to the charts presented in Figures 8a-8d. Each of these graphs was produced by a Hewlett Paskard Spestrum Analyzer, model No. 8568 B. The following examples do not use the same bandwidths, modulation frequencies and deviations as the examples above. However, the change of fresh scale did not influence the results in such a way that the relationships presented to sontinuasión are valid in general. Referring now to Figure 8a, an interfering signal 800 represents a harmonization of an unmodulated clock signal (not shown). In particular, the interfering signal 800 involves a large interfering skeletal component 801 centered around 450 MHz. The peak 802 of the interfering spectral component 801 is -20 dBm in this example. If it is desired to significantly attenuate the interfering spectral component 801 to virtually eliminate the interference within a bandwidth of the receiver band centered around 450 MHz, then the unmodulated clock signal should be modulated in frequency to be a square wave of 10 kHz and a modulation index in the interfering component of 450 MHz approximately equal to 2. The effect that this has on the interfering signal is shown in the graph of Figure 8b. Here, the interfering signal 800 'has an interfering spectral component 803 representing an attenuation of mAs of 60 dB in somparation are the interfering spectral component 801. Likewise, the sidebands 805 that are generated by the application of this tansy are at 10 kHz of the central milling of the 450 MHz receiver and therefore are outside the bandwidth of the receiver. Figure 8s is a graph showing the effect of the frequency modulation of a clock signal (not shown) is a sawtooth wave of 1 kHz having a sweep bandwidth of 20 kHz at the component frequency i nterferente. This should result in the potency of somatic signal between approximately 20 components in such a way that the attenuation should be approximately 20 veses, or -13 dB. This corresponds to the actual 807 ateputation of -12.5 dB, as shown in Figure 8s. The anhure of the medius band used to generate the graph in Figure 8s is 300 Hz, which is less than the distance between the components. . Therefore, as a maximum only one component can be measured at a time. It is also a measurement of peak potency. There is no difference between the peak potency and the average potency because only a signal of constant amplitude is found in the bandwidth of the measurement band. Referring now to Figure 8d, the same spectrum is presented again as in Figure 8s. However, here the interferent signal has been measured is a band anhure of 3 kHz which allows the presence of 3 components in the width of the. band. It is a peak potency measurement. An approximate factor indicates that the value of the voltage of the measured voltage must be increased 3 times, which corresponds to 9.5 dB in somparation, and it is the measurement efestuated in the. Figure 8s. The actual attenuation 809 (-1.9 dB real = approximately -12.5 dB real + 9.5 dB estimate) corresponds to this estimation. The invention has been referred to a partisan modality. However, those skilled in the art will understand that it is possible to make this invention in different spherical forms of the preferred embodiments described above. This can be done without departing from the spirit of the invention. The preferred embodiment is only an illustration and should not be construed in any way as a limitation. The scope of the present invention is provided in the appended claims and not in the foregoing description and all variations and equivalents that fall within the scope of the claims are considered covered within the present invention.

NOVELTY OF THE INVENTION Having described the present invention, it is considered a novelty and, therefore, it is claimed in property what is contained in the following

Claims (1)

1. CLAIMS 1. In an electronic device that includes an interfering part that generates, from a first signal, an interferensia signal having a spectral component within a bandwidth of a receiver, a method to reduce the interference within The width of the band of the receiver comprising the step of: angularly modulating the first signal is a noiseless, deterministic modulation signal, where an angularly modulated interferensia signal having lateral modulation bands that lie outside the anhure of the band of the receiver and a reduced carrier wave amplitude is generated by the front part, 2. The method of the re visions ion 1 where the noiseless, deterministic modulation signal is a sinusoidal signal. 3. The regression method 2 where the angularly modulated interferometer signal has a modulation index, ß, which fulfills a relationship Jo (ß) < R, where R is a predetermined relationship between a modulated carrier wave amplitude and an unmodulated carrier wave amplitude, 4. The method of the re visions in 1, where the noiseless, deterministic modulation signal is a superelevated wave eim trisa. 5. The method of claim 4, wherein the symmetric square wave has a repetition frequency sufficient to cause the lateral bands of modulation of the angularly modulated interference signal to pass out of the bandwidth of the receiver. 6. The method of the re visions ion 4 where the angularly modulated interference signal has an index of modulation, ß, which fulfills a relation (2 / p) without (p.β / 2) R, where R is a relasion default between a modulated carrier wave amplitude and an unmodulated carrier wave amplitude. 7. The method of the. rei vindisasión 1 where: the apparatus elestróniso also includes a first part that supplies the first signal to the interferential part; and the angular modulation step of the first signal comprising the steps of: applying a direct frequency modulation a. the first part is the modulation signal without noise, deterministic, to generate a first modulated signal; and to aply the first modulated signal to the interfering party to generate the. angularly modulated interferens signal having modulation side bands that lie outside the bandwidth of the receiver. 8. The method of the vindisation rei 1 where: the apparatus elestróniso additionally insides a first part that supplies the first signal to the interfering part and the angular modulation step of the first signal that suffers the step of: modulating in phase the first signal is the noise-free, deterministic modulation signal, before supplying it to the interfering party whereby the interfering party generates the angularly modulated interference signal having modulation sidebands that lie outside the width of the receiver band. 9, The method of the re vi ndisas ion 8 further comprising the step of supplying the first unmodulated signal to a non-interfering part of the astronomy apparatus. 10. In an electronic apparatus that includes an interfering part that generates a combined signal that suffers a first signal and an interference signal having a spectral component within one. bandwidth of the receiver, a method for reducing interference within the bandwidth of the receiver comprising the step of: angularly modulating the signal combined with a noiseless, deterministic modulation signal, whereby the interfering part generates an angularly modulated interferene signal having lateral modulation bands that extend outside the anhura of the. band of the septor and one. carrier wave amplitude reduced. 11. The method of the relay 10 where the noise-free modulation signal, deterministic, is a sinusoidal signal, 12. The method of resonance 11 where the angularly modulated inter-signaling signal has an indise of modulation , ß, which fulfills a recession Jo (ß) <; R, where R is a predetermined reiasion between the amplitude of the carrier wave, modulated and the amplitude of the unmodulated carrier wave. 13. The redisplay method 10, where the noiseless, deterministic modulation signal is a symmetric square wave. 14. The redisplay method 13, where the symmetric square wave has a repetition frequency high enough to cause the lateral bands of modulation of the angular modulated interferens signal to pass out of the bandwidth of the receiver . 15, The reverse vindisation method 13, where the angularly modulated interference signal has a modulation index, β, which suffers a recession (2 / pß) if n (pß / 2) R, where R is a predetermined relasion between a modulated carrier wave amplitude and an unmodulated carrier wave amplitude. 16. The method of ion reindication ion 10, where the step of modulation angular of the combined signal somprende the dilisasión diresta of modulation of frequency to the interfering part are the modulation signal without noise, deterministic, so that the interfering part generates the signal of angularly modulated interference having lateral bands of modulation that lie outside the width of the receiver band, 17. The reverse binding method 10, wherein the step of the angular modulation of the combined signal comprises the modulation in phase of the signal combined with the noiseless, deterministic modulation signal, before supplying it to a first component in the electronic apparatus, whereby the interference signal becomes angularly modulated interference signal having lateral modulation bands that are out of the gap of the receiver's band. 18. The method of the indiscrimination 17, further comprising the step of supplying the unmodulated combined signal to a second component in the electronic apparatus. 19. In an electromagnetic device that includes an interfering part that generates, from a first signal, an interference signal that has an interfering spectral component within a width of the measurement band, a method to redress the inter ference within of the bandwidth of the medicion band that comprises the step of: using a modulation signal to apragularly modulate the first signal, whereby the interfering part generates an angular modulated interference signal having a reduced spectral component within the width of the band d? measurement, the reduced spectral component is smaller than the interfering spectral component, where: the modulation signal is a noiseless, deterministic wave, and an anhura of the modulation band of the angularly modulated interferometer signal exceeds the width of the Meditation band 20, The method of claim 19, wherein the modulation signal is a sawtooth wave. 21. The redisplay method 20, where the frequency of the sawtooth wave is selected within a range of frequency values, the range of frequency values has a low frequency value substantially equal to the width of the measuring band and a high frequency value sustains only 1.5 times the bandwidth of the measurement band. 22. The method of claim 19, wherein the angular modulation step of the first signal comprises the steps of: applying a direct frequency modulation to a first part that generates the first signal; and supplying the first frequency-modulated signal to a transmitting generator within the interfering part instead of the first signal, the transmitting generator being responsible for the generation of the interference signal. 23. The method of the re vindisas ion 19, wherein the angular modulation step of the first signal comprises the steps of: modulating the first signal in phase; and supplying the first signal modulated in phase to a sirsuite generating emission within the interfering part instead of the. First signal, the sirsuito emission generator is responsible for the generation of the signal of interference. 24, The method of the vindisation ion 23, further comprising the step of supplying the first unmodulated signal to a non-interfering part of the electronic apparatus. 25. In an astronomical apparatus that includes an ipterferent part that generates a combined signal comprising a first signal and an interference signal having an interfering skeletal component within a bandwidth of the medial band, a method to reduce the interference. Interference within the bandwidth of the measurement band, which comprises the steps of: using a modulation signal to angularly modulate the combined signal, whereby an interference signal is generated is an angular cell having a reduced spectral component within of the band's hunger, of measurement, the reduced spectral component is smaller than the non-interfering spectral component, where: the modulation signal is a noiseless, deterministic wave, and a bandwidth of modulation of the signal of 15 inter ferens ia Angular modulation exceeds the width of the medial band. 26. The rewind method 25, where the modulation signal is a sawtooth wave. 27, The method of the re vindisas ion 26, where the frequency 20 of the sawtooth wave is selected within a range of frequency values, said range of frequency values has a low frequency value substantially equal to the width of the measuring band and a high frequency value substantially equal to 1.5 times the bandwidth of the measurement band. 28. The method of thedisplay 25, wherein the angular modulation step of the combined signal comprises the frequency modulation aplissation diresta to the interfering part. 29. Rei vindisasi on method 25, wherein the angular modulation step of the combined signal comprises the in-phase modulation of the combined signal; and further comprises the step of supplying, instead of the combined signal, the combined signal modulated in phase to a first component in the electronic apparatus. SUMMARY OF THE INVENTION In an electronic apparatus that includes a reference ossilator and an interfering part that generates an interference signal having a spectral component within a width of the receiver band, the reference oscillator supplies a reference oscillating signal to the interfering part from which the interference signal is derived from the interference signal, the amplitude of the interference signal within the bandwidth of the receiver is reduced by angular modulation of the reference oscillating signal, which is a sinusoidal signal for generate an angularly modulated interference signal? which has a reduced carrier wave amplitude and lateral bands of modulation that are outside, of the bandwidth of the receiver. The angularly modulated interference signal preferably has a modulation index, (ß), which is close to a solution of the equation Jo (ß) = 0, where Jo is a Bessei funsion of the first type. The angular modulation can be achieved alternately by the frequency modulation of the frequency reference to the reference ossilator are the sinusoidal signal to generate a modulated reference signal and then apply the reference signal modulated to the interfering part, or by in-phase modulation of the reference oscillating signal with the sinusoidal signal before supplying it to the interfering part. When the interference signal has an interfering spectral component within a range of the medial band, the amplitude of the interfering skeletal element is reduced by the use of a noiseless, deterministic modulation signal, such as a signal modulation signal. Sawtooth wave for modular angularment? a clock signal from which the signal d is derived? i nter ferensia. In testimony of which, I have signed the previous description and novelty of the invention as a proxy of ERICSSON INC., In Mexico City, Federal District, today, January 3, 1996. p.p. from: ERICSSON INC.