JP2002185545A - System and method of low interference signal transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system of a low interference signal transmission which is essential for utilizing a device which is designed for a non-contact high-speed data circuit, in particular a very large-sized open system, for example, a computer X-rays tomography device (CT scanner means). SOLUTION: In this system, via a line connection, or a contact may be made with a transmission circuit, in particular in a rotary transmitter, via a non- contact transmission circuit, preferably, a signal, in particular, a low interference signal of a digital signal is transmitted from the transmitters which are moved mutually to receivers which are separate at intervals. In a modulator device, concerning a signal to be transmitted and a carrier signal of a transmission means in the transmitter, or a transmitter output signal which may be located anywhere in the transmission circuit, an output signal spectrum of the transmitter is enlarged independently of a modulation selected on a signal transmission, and therefore the modulator device modulates so that a spectrum power density of the transmitter output signal is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the improvement of the electromagnetic field compatibility of data lines, and more particularly, to the improvement of the electromagnetic field compatibility of digital data lines, and more particularly to a system and method for transmitting low-interference signals in digital signal transmission.

[0002]

2. Description of the Related Art The use of digital data lines is constantly expanding. In most cases, digital signal transmission has shown significant advantages over analog transmission. The cost of high-speed data channels will be curtailed by the development of new transmission technologies. The width of individual channels has become extremely inexpensive, and multiplexing several low-speed signal lines to form a single high-speed signal line is often the best economic solution. This was fulfilled in particular by high-speed rotating connectors.

A conventional solution for transmitting large volumes of data from rotating parts to stationary parts has been the parallel application of multiple slip ring paths. This resulted in a very heavy monolithic structure and was expensive. Although mechanical slip rings are particularly suitable for energy transmission, the transmission of vast amounts of data has several significant disadvantages, such as bandwidth limitations, contact noise and failures.

[0004] Due to the large number of circuits with data transmission capabilities approaching the physical limits of the contact slip ring path, service life and maintenance are of primary concern. The new contactless high-speed circuit overcomes all of these problems and allows for a service life without maintenance concerns with the highest quality transmission and almost unlimited bandwidth.

A very important aspect that can be applied to any electronic device, not just a contactless high-speed line, is electromagnetic field compatibility. Electromagnetic emissions are most important in wire-based circuits and unshielded rotating connectors, but transmitters, receivers and even amplifiers in fiber optic system circuits emit electromagnetic fields.

[0006]

SUMMARY OF THE INVENTION In response to the prior art,
Optional Signals In particular, digital signals are transmitted in more or less predominantly sharply angled signal strings. These signal strings show a clear broad line spectrum as a function of the respective coding. This spectrum results in interference of the radiation already in closed or shielded systems, but is particularly common in open systems, for example rotating transmitters which interfere with radiation.
Exceeds the limits specified in the MC standard. In this regard, contactless open transmission systems, such as those used for line or rotary transmission, are particularly problematic. It is clear that leak line systems are also affected by this effect.

Various countermeasures have been known for reducing the amount of noise. For example, a low pass filter or even a band pass filter is suitable for limiting the transmitted frequency range. However, this is possible, but only with difficulty, especially for transmissions in broadband transmission systems, for example at 200 Mbaud. For example, a minimum bandwidth of 140 MHz requires a 200 Mbaud circuit. Another measure is to reduce the transmission signal level. However, such measures result in poor signal-to-noise ratios and, therefore, a reduced bit error rate in digital systems. By taking measures corresponding to the prior art, the EM of such a transmission circuit
Improving the C characteristics without appreciable loss can be difficult but difficult. European Patent Publication No. 01
From 63313A2 a device for distributing spectral energy emitted by a digital system and a method for distributing it are known. This solution is built into the components that are deployed in every personal computer today. However, this method is not suitable for transmitting a signal between a transmitter and a receiver that move with respect to each other. A device using part of the above-described solution of the present solution is known from EP-A-0,505,771 A1.
According to this reference, the spectrum of the output signal from the transmitter is expanded, so that the spectral power density of the output signal for transmission is reduced. In this method, so to speak, the signal is shortened and the phase is shifted by the length. That is, the bandwidth of the signal is also greatly changed. On the other hand, the solution of the present invention described in detail below aims at providing a method and apparatus for transmitting a signal having a low interference power, which is very small even if the signal bandwidth changes.

[0008] It is therefore an object of the present invention to form a digital transmission circuit, in particular a contactless rotary transmission circuit, wherein the emitted noise level is, within the meaning of the current EMC standard, of the quality characteristic of the transmission. It proposes a system and method for low interference signal transmission that can be reduced without a corresponding impairment.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to how electromagnetic field compatibility (EMC) is dependent on emitted signals, especially in high speed data circuits, and how these signals are related to electromagnetic emissions. It discloses whether it can be changed by minimization by the method, the gist of which is via line connection,
Alternatively, the transmission circuit may be contacted, in particular in the case of rotary transmitters, preferably through a contactless transmission circuit, preferably from a mutually movable transmitter to a receiver spaced apart from it, in particular of a digital signal. A system for transmitting an interfering signal, comprising: transmitting a signal to be transmitted by a modulator device and a carrier signal of a transmission means in a transmitter or a transmitter output signal which may be located anywhere in the transmission circuit. What is claimed is: 1. A system for transmitting low-interference signals, characterized in that the output signal spectrum of the transmitter is modulated irrespective of the modulation chosen for transmission, so that the spectral power density of the transmitter output signal is reduced. It is in.

According to the present invention, by modulating the transmission cycle,
In this way the transmitted line spectrum of the signal is broadened, although the gap between the individual spectral lines is buried, thus reducing the average spectral frequency. The system of the present invention comprises a transmitter corresponding to the prior art, which broadens the spectrum of the clock generator and further the transmitter output signal to the transmitter or each of the clock generators or anywhere in the transmission circuit. As well as an additional modulator controlled in such a way as to be controlled. Such control may be phase or, for example, frequency modulation. Amplitude modulation or other modulation techniques are equally conceivable. Moreover, a special controller is provided to provide a modulator device for supplying a modulation signal.

[0011] The present invention relates to a "spread spectrum".
Clock Generator (Spread Spectr)
um Clock Generator) ”
USA, March 997, San Jose, CA, 3
EM of an integrated circuit known from the prior art from a publication by the 725 North Street Company of IC Works
It is clear that this is distinguished from a modulation technique for improving the C characteristic. This prior art reference relates to improving the EMC characteristics of the computer board, not of the transmission circuit.

Here, the effect of spectrum spreading on EMC characteristics will be described. Defining the general term "magnetic field compatibility (EMC)" is difficult. Here, reference is made to the very general CISPR11 standard. It specifies the limits for maximum emission of electromagnetic energy and specifies suitable measurement techniques. This criterion determines the derived emission capacity at frequencies between 30 MHz and 1 GHz. The emitted power is measured in 120 kHz steps with a bandwidth of 120 kHz. Having a homogeneously distributed broadband spectrum is not absolutely necessary for the spectral broadening technique, but the only thing that needs to be considered is the fact that the same amount of energy is supplied in each 120 kHz range. . This can be achieved using a broadband signal or individual narrowband peaks in this range. In most applications, spectral broadening with a line spacing of 120 kHz from each other or a safety line distance of 100 kHz is the property of the most inappropriate solution. This further broadening of the spectrum requires the introduction of very small frequency fluctuations in the data stream. In some applications, these modifications occur spontaneously, eg, as “true data”, eg, when a video signal is transmitted. However, in extreme situations, such as when the video signal is deactivated and only digital zeros are transmitted, measures need to be taken to ensure that the spectrum is wide enough to accept the EMC specification. There is.

In the application of high-speed digital data circuits, considerable measures need to be taken to ensure that the essential requirements of the international EMC regulations are met. At data rates of hundreds to thousands of M baud, the reference frequency falls under the common transmission, broadcast and television bands. The general reduction of interference is a low frequency spectrum with a homogeneous distribution of the information, rather than one containing a few individual high power spectral lines.
It is better to transmit as two broadband signals.

The present invention discloses how commonly applied digital data circuits can correct significant spectral broadening in this manner.

There are two supplementary techniques that can be used to achieve this problem. The first technique is to code the digital signal appropriately. A further technique is some kind of frequency modulation. This frequency modulation can be performed without affecting the transmitter or receiver anywhere in the circuit.

According to the invention, conventional data coding is advantageously continued for optimizing EMC characteristics.

Next, the expansion of the carrier signal (data cycle signal) of the transmitter will be described. In the transmitter, the timely development of the data flow can be controlled simply by controlling the carrier signal of the transmitter. This requires direct access to the transmitter carrier signal. One of the traditional solutions is
The idea is to replace the newly modulated oscillator with a standard quartz oscillator device in the same device.

In a particularly advantageous embodiment of the invention, the modulator device is arranged to apply the cycle frequency of the oscillator clock generator to a frequency modulation corresponding to the modulation signal of the controller device. In this configuration, the implementation by placing the VCO on the frequency determining element of the clock generator, which changes the frequency of the clock generator as a function of the control current applied to it from an engineering point of view, is particularly simple. The control voltage of this VCO is predetermined by the controller device. If the controller device now supplies a low-frequency signal, the frequency of the oscillator's clock generator changes with the cycle of this signal, so that it is frequency modulated.

Frequency modulation is a direct method of spectral broadening. A serial standard transmission circuit, such as TAXchip or Hot-Link, calculates the static variation from the cycle frequency to ±
Allow only 0.1%. The limit of friction set for the quartz oscillator tolerance requires that the variation of the maximum frequency be less than or equal to 10 ⁻⁴ . Since spectral line broadening does not provide the advantage below 100 kHz as detailed above, the minimum data rate f _{Dmin for} low frequency shifts is:

[0020]

(Equation 1) Which is based on the following equation:

[0021]

[Equation 2] _Where n _Frame indicates the number of bits in the data block, f _Data indicates the f _{M in} data cycle frequency, indicating the lower frequency limit.

This indicates that at low data rates below 1 Gbaud, no improvement can be provided.

Phase modulation is simply achieved by inserting a control electrical delay into the carrier signal (or each of the clock signals). The low frequency of the phase modulation can be controlled automatically in a timely manner by the receiver PLL, but it does not result in a significant expansion of the spectrum. Although very high frequency phase modulation produces a favorable effect on the spectrum, its operation can be compared to additional synchronization disturbances on the receiver input.

In another advantageous embodiment of the present invention, the modulator device comprises a transmitter signal processing and modulation stage (stag).
e), which can directly modulate the output signal of the transmitter.

According to the invention, the spectrum can also be expanded by modulating the transmitter output signal (or each of the data streams). Transmitter output signal (or each of the data streams) modulation or state modification
ion) itself has significant advantages over state modification of the transmitter carrier signal (or each of the transmitter data cycle signals). State modification of the transmitter is not necessary per se. The transmitter output signal (or each of the data streams) can be state modified anywhere in the transmitter circuit. Therefore, the system allows for reduced development costs and smooth integration into existing designs, and does not require any state modification of the transmitter design.

In a further advantageous embodiment of the invention, the transmitter comprises a delay circuit controllable by the control generator, which delays only the isolated pulse or the output signal end in proportion to the predetermined low modulation frequency by the control generator. . In the sense of the present invention, the term "transmitter"
Should be understood to represent the processing and combination of data, signals or cycles, and to the combination of all devices performed in such a way that they can be transmitted via the transmission circuit itself. For the purposes of the present invention, this delay can be achieved in the clock generator of the transmitter, or in the next stage, or even in the driver circuit of the transmission circuit.

The best way to modify the state of an existing data stream without any effect on the data transmitter is therefore to employ a control delay. The data stream is supplied to the delay controller means to divide the data stream and to control the control signal VP
Is generated for the control delay circuit. This circuit delays the data flow for the interval defined by VP. An almost static delay modulated by low frequency corresponds to phase modulation.
This type of phase modulation has only a small effect on the width of the spectrum. In phase modulation, the width of the spectrum is largely independent of the modulation frequency. Therefore, the modulation angle needs to be increased for spectrum expansion. Relatively high modulation requires specific circuitry including storage elements, which can no longer be implemented with planar delay elements. Certain frequency modulations are more advantageous here. Frequency modulation is a special case of phase modulation and has an integrated phase angle over time. Moreover, phase conversion can be conveniently performed by clock recovery techniques.

In addition to modulation by the modulator device, data coding with pseudo-random noise can be advantageously implemented.

In accordance with another advantageous embodiment of the present invention, a controller device is disposed at the receiver and controls the clock generator of the receiver in synchronization with the modulation of the transmitter. This synchronization can optionally be carried out via a signal which can be used jointly by the transmitter and the receiver, for example a network frequency.

In a further advantageous embodiment of the invention, a controller arrangement is provided in the receiver, in the case of modulation of the frequency of the clock generator of the transmitter, the clock generator of the receiver being synchronized with this modulation, the received signal being modulated. Controls further processing in a non-modulated form at the receiver.

In another advantageous embodiment of the invention,
An additional signal is transmitted in parallel to the transmission circuit between the transmitter and the receiver for modulation control. Here, because of this additional signal, demodulation takes place at the receiver and is synchronized with the modulation at the transmitter.

[0032]

FIG. 1 shows an inventive system comprising a transmitter 1 connected to a receiver 3 via a transmission circuit 2. The transmitter 1 comprises a modulator device 4 and a controller device 5
Is controlled via With this controller, a modulated signal, which modulates the transmitter signal or the frequency of the clock generator, respectively, is generated in such a way that the spectrum of the output signal transmitted via the data channel 2 is broadened. For receiver circuits corresponding to the prior art, especially the frequency modulation of the transmitter signal is not a problem. The state modification of the frequency, especially of the low modulation frequency, has no problem, and the PLL provided for the data and period reconstruction in the receiver.
Is finely controlled.

FIG. 2 shows the spectrum measured at the absorber hole, which is emitted via the data circuit 2 by a transmitter according to the prior art.

FIG. 3 shows the spectrum of the inventive system, where a control generator is used to frequency convert and modulate the transmitter signal by 2 MHz. As a result, the fractional part of the spectrum also becomes a gap between the spectral lines. Thus, using the same output signal amplitude, the power density in the individual frequencies is reduced. Maximum amplitude reduction is almost 16
It varies in the range of dB.

As for the frequency spectrum of a digital signal, the data stream is also in PCM format, as found in almost all digital data links, meaning that there are only two digital levels, zero and one. . Information is included when multiple zeros and multiple ones coexist in a defined time window. For alternating signals of zeros and ones, the waveform corresponds to a symmetric rectangular wave (FIG. 4) whose frequency corresponds to half the bit period rate. Such a signal exhibits the generally known spectrum shown in FIG.

What is visible is only the odd harmonic having an amplitude that decreases linearly. Harmonics only occur when the signal is asymmetric. When the signal has other patterns with relatively wide time periods of zeros and ones, as in the signal of FIG. 6, the sidebands have offsets that are multiples of the frequency components of these longer time periods. Appear in the spectrum. This leads from a plain needle spectrum to a multiplied and diversified spectrum as shown in FIG.

When there are a very large number of different patterns, for example in different combinations, the spectrum is subject to ever-increasing diversification. For most digital signals,
The average power of the data is constant. For measurements over a fairly long time, the numbers of zeros and ones are approximately equal. For example, the average power P _Mean of the random binary signal is the average power of zero P ₀ and 1P _{1 as in} the following equation.

[0038]

[Equation 3]

In terms of the spectral representation of the sum of all the amplitudes A _i of the spectral lines, this sum is thus equal to:

[0040]

(Equation 4)

Regarding the reduction of the spectral power density, in the first embodiment of the invention (FIG. 4) of the pattern 1010, a high energy level is present at the signal and its harmonic reference frequency. If the signal is expanded to additional frequencies, the energy of the individual spectral lines needs to be reduced because the total energy is constant. Hence, unlimited expansion of the bandwidth theoretically results in an infinite low energy density. However, there are some limitations in practice.

Even if the bandwidth is less expensive,
Unlimited bandwidth is expensive. Thus, a good design of the data circuit does not use more bandwidth than necessary for transmitting information. However, filling the gaps between the spectral lines can also provide considerable improvement. Signal coding and waveform shaping do not require additional bandwidth for data link optimization, and instead of individual spectral lines,
It must be done in such a way that a stationary power spectrum with a frequency-independent power density coexists. FIG.
Shows a typical needle spectrum with a second graph of spectrum modified to a relatively wide bandwidth with a frequency modulation (FM) of 2 MHz with a second graph of the spectrum of the same signal at 1010 signals. There is no significant difference between these two signals.

This can be significantly improved by slightly modifying the signal's EMC characteristics of the digital link.
Hereinafter, various techniques for spectrum expansion will be described.

To explain the general data coding scheme, the data is implemented as a normal block, including additional blocks and error detection bits. These additional bits also need to synchronize the data receiver and transmitter. Defined coding such as 8B / 10B
Are often used to perform these tasks. Very long data streams, which do not consist of anything other than zeros and ones, will never occur. A typical block with synchronization and error correction bits has an n _Frame size of roughly 10 to 20 bits. This will provide spectral line spacing with relatively low frequency limits and block repetition rates, even if the data contains nothing but zeros and ones. The relatively low frequency limit f _{Min in the} number of data periods f _Data and the minimum distance between the spectral lines correspond to the following equation.

[0045]

(Equation 5)

By convention, the data is additionally encoded to guarantee DC freedom and increase the redundancy of smooth error detection. Both data implementation and coding can expand the spectrum. Low packaging densities result in relatively high packaging repetition rates and therefore moderate expansion of the spectrum. For example, at a data period signal rate of 200 MHz, a 10-bit block results in the interline distance of the next spectral line.

[0047]

(Equation 6)

This is because the spectral lines are 100 MHz, 30
It happens not only at 0 MHz, 500 MHz, etc.
Additional spectral lines also occur in the spectrum with a line spacing of 0 MHz. This provides five times as many spectral lines with an average reduction of only 7 dB of power. Such coding alone is not sufficient for effective EMC improvement.

Referring to a pseudo-random pattern, a data stream comprising a plurality of zeros and a plurality of 1 random successions results in a very homogeneous spectral distribution. In theory, an infinite random succession results in a fully expanded spectrum with a constant spectral power density. It is inappropriate that such a data stream cannot contain the desired information. In this solution, it is possible to use deterministic pseudo-random patterns. These patterns consist of a predetermined sequence of reproducible bits. As a rule, the length of these patterns is determined. These patterns are said to be pseudo-patterns, even if they submit a defined succession, and even if they can be expected, at first glance they look like random runs.

The effect of the pattern length on the spectral density will be described. A pseudo pattern used in an actual application has a limited pattern length. After emitting the _nP bits, the same pattern is repeated. The reason for short patterns is the limited storage for pattern storage and relatively simple synchronization. With a long pattern, thus
Low pattern petition rates provide low frequency components to the signal and thus spread over narrow inter-spacing spectral lines.
The minimum distance Δf between adjacent spectral lines is mutually proportional to the length n _P of the random pattern.

[0051]

(Equation 7)

Therefore, a long pattern length is preferable for the distance between the small lines of the spectral lines. The effect of pattern length is shown in FIGS.

In FIG. 10, the spectral line is 1.56 MH
While the distance between lines is taken by z, the amplitude is -3.
6 dBm. If a relatively long code string is chosen as shown in FIG. 11, the pattern length is 256
At twice the length, the spectral lines have a line spacing of 6.1 KHz, which represents a straight line below the resolution of the spectral refractor. The amplitude of the spectral line (which is the same as the line amplitude) will be -609 dBm, corresponding to exactly 256 times the previous amplitude of -36 dBm. In FIG. 12, the pattern length is used, which is four times the previous length, resulting in a signal amplitude that is four times smaller (-6 dB).

To illustrate the application of the prior art pseudo-random pattern, an approximation of a plane of a very short pseudo-random string is a coding scheme, such as commonly applied 4B / 5B or 8B / 10B coding. is there. Where the 8-bit binary number is 1
It is encoded into a sequence of 0 different bits. In this way a long succession of zero bits is not derived from zero. These patterns create a slight magnifying effect,
It results in a more homogeneous spectral distribution.

In addition, a very common application of pseudo-random patterns is bit error rate testing, where the wide band of these patterns allows a thorough check of the entire transmission system.

Describing the static pattern, mainly the serial transmitters have no data to transmit.
Works with blank characters. This blank makes the identification "no data" in an obscured pattern, and also allows for receiver synchronization with the transmitter clock signal. There is usually only one type of blank pattern. If no data is transmitted for a long time,
Only this pattern is transmitted through the circuit. that is,
Presents the same length as the standard data word, and thus has a relatively high low frequency and spectral line spacing derived from Equation 7. Such patterns do not usually exhibit a straight distribution of their spectral lines. Thus, a high data link may display excellent EMC characteristics when actual data is transmitted. However, as soon as the transmission is over and the blank is transmitted, the EMC properties are strongly impaired. These static patterns are the most inappropriate states of electromagnetic emission or transmission, respectively. If transmission of these patterns cannot be avoided over a long period of time, EMC measurements need to be performed under these conditions.

In the definition of an acoustic system, such a static pattern must be avoided by all means. This can be achieved by transmitting a variable receiver blank, by transmitting a blank character, or by emitting a pseudo-random string that signals the blank character state. Even a long string of zero signs encodes this string with a pseudo-noise signal having a long pattern length.

Next, the method for expanding the band width of the present invention will be described. As described above, there are various methods for expanding the spectrum. At least two effects on electromagnetic emissions
A method of completing one another is used. A very good combination is a timely coding with some kind of data variation modulation of the pseudo-noise data. Timely data variations can be modulated in various ways. One method is to condition the original data periodic signal at the transmitter end. Another alternative is the timely modification of variables in the data stream itself.

For data coding, as described above, the data stream must have the appearance of a random string for optimization of EMC characteristics. Real data really often displays random characteristics. In the measurement of a signal or a video image signal, certain noise always occurs, which also has an effect on the random characteristics. In another case, coding the data stream with random strings yields favorable results. This coding is very easy to implement. When data is transmitted in large blocks,
Each block can be subjected to a dedicated O-ring method (FIG. 13) with a predetermined random string. Here, the transmitted signal has the appearance of a random signal. Even in the worst case of strings of zeros or ones, the signal looks like a random signal.

The receiver can reconstruct the original data as an original data block by a dedicated O-ring of the block with the same random string. Alternatively, the signal can be sent to a traditional pseudo-random generator, which can be based on a feed register with feedback.

Also, if there is a particular situation, it should be focused on. Most data parallel-to-serial converters present a defined "no data" signal and can synchronize these converter data if data is lost. If no data is supplied to the parallel-to-serial converter, this short data word, usually consisting of a sequence of 10 to 20 bits, will be transmitted continuously. This signal results in a very wide frequency line spacing and very poor EMC characteristics. Therefore, it should be avoided at all costs that the static pattern remains pending for transmission. To prevent this situation, the data needs to be fed to a parallel-to-serial converter. This can be implemented by a simple software state modification. Instead of transmitting no data, the same block that is dedicated to the data but is filled with multiple zeros or some other pattern that can be identified as "no data" can be transmitted. When multiple zero streams are subjected to an OR combination with a dedicated random pattern, this applies a complete random pattern to the data link, and thus the top EMC
Supply properties. Following a dedicated OR combination with a random pattern, multiple zero streams can be easily identified as "no data" to the receiver.

As described above, the distance between the spectral lines is
It is inversely proportional to the pseudo random pattern length. The minimum distance between the spectral lines can be calculated by Equation 5. The data coding task should be completed with the use of variable timely modulation techniques. When very long code strings are not used, data coding techniques are optimal for providing coarse expansion, while timely modulation of variables is the best way to provide excellent expansion.

To achieve the relatively low data rate improvement in the case of frequency modulation, the periods need to be shifted by a minimum of 10 ^-4 . This can be achieved by synchronizing the transmitter with the period of the receiver. Finishing this transfer requires that a low frequency message transmission be provided between the transmitter and the receiver. Such information can be transmitted over additional low frequency lines or, in the case of rotating connectors, over conventional slip-ring lines. In such cases, noise and bandwidth are not critical. Another method is to use some signals that are already available jointly, such as in the case of an AC energy circuit that modulates the synchronization between transmitter and receiver periods. Therefore no additional signal is needed.

Better results can be achieved with modulation of a clock signal having a very high frequency proportional to time. The modulation must be very rapid so that the receiver PLL cannot keep up with frequency changes. If the overall phase is too large, the receiver may lose data. In such a case, a similar technique can be applied, for example, as described in the introduction for the phase technique. This solution generally needs to match the link as well as its actual data cycle rate.

FIG. 14 shows a schematic diagram of the circuit configuration of the phase shift technique.

FIG. 15 shows a phase modulated signal with 6.28 rad modulation at 10 KHz.

FIG. 16 shows a type of frequency modulation with 1 MHz frequency modulation. This frequency modulation is a special case of phase modulation with integrated phase angle over time. A simple example of such a frequency modulated signal is shown in FIG.

The input signal presents a steady periodic velocity. This means that the intervals t _n -t _n-1 have the same width. In the case of a controlled delay circuit, times t ₀ , t ₂ , t ₄ ,
While the clock signal variation due to t ₆ and t ₈ does not present any delay, the variation due to times t ₃ and t ₇ has a small positive delay △ and a small negative variation at the locations of times t ₁ and t _5. Display the delay-Δt. As a result, the first clock signal period T ₁ is greater than the second clock signal period T _2.
T ₁ because its is expressed by the following equation.

[0069]

(Equation 8)

For this purpose, the reference frequencies of both clock signal periods are equal.

[0071]

[Equation 9]

[0072]

(Equation 10)

Here, the number of spectral lines has doubled (FIG. 18).

For a further increase in the spectral lines, the introduction of additional frequencies f ₁ and f ₂ is possible. To achieve this, it is only necessary to change the delay Δt in accordance with equations 9 and 10.

To this end, the delay control means is controlled by the additional modulation generator, forcing the delay control means to pass all delays between Δt _Min and Δt _Max at very low frequencies. Therefore, the spectral line between f ₁ and f ₂ are filled as shown in Figure 19.

Because of the minimal added delay, the signal is similar to a signal with additional low synchronization disturbance (jitter) (see FIG. 20). This additional jittering provides two spectral components that need to be considered. Initially, high frequency modulation behaves like bump jitter. It is affected by link characteristics. However, for contactless rotating connectors that provide 5% jitter, 5% additional modulation jitter is acceptable. Most digital link receivers can accept 20% jittering without any impairment. The low frequency component of the modulation generator is chosen such that the period is slightly shorter than the period of integration of the EMC measurement. The measurement according to CISPR11 lasts for 10 ms. Therefore, the modulation frequency needs to be higher than 100 Hz. This low frequency is rejected by all receivers.

Referring to the periodic regeneration technique, another method of modifying the state of the spectral characteristics of a data stream is to use a complete synchronization (retiming) circuit. FIG. 21 shows a basic mode of operation (Mode). The data stream is provided to a PLL circuit for recovery and regeneration of the data period. The recovered clock signal is supplied to a data flow synchronization (retiming) circuit. Additional modulation generator means modulates the data stream by changing the PLL frequency.

This circuit delays operation similar to the characteristics of the above-described circuit, but additionally provides synchronization (retiming) and, therefore, reduction (reduction) of data flow jittering. There are two possibilities available for PLL control. The first opportunity is to modify the state of the digital PLL output signal and introduce additional delay. Another possibility is control by a VCO analog signal. The implementation of this concept requires a VCO
Supplies a small negative pulse initially supplied to its control voltage, 1
After a period or several periods, a small negative pulse having the same amplitude can be supplied to the VCO. This results in rapid transient frequency changes, making the PLL inherently very fast, so that the PLL itself cannot keep up.

As with periodic modulation, additive jittering is introduced into the data stream.

To further describe measurements on state-modified digital signals, some final measurements show the advantages of PCM signals with extended spectra. FIG.
Indicates the worst condition at 200 Mbaud of the 1010 signal. Here, the peak value at an amplitude of 100 MHz is -14.
Equal to 7 dBm. If a genuine 8B / 10B encoded signal is used, the spectrum will have the appearance shown in FIG. In this embodiment, the maximum amplitude is now -20.6d
Bm, while the minimum distance between spectral lines is 2
0 MHz. Due to the short length coding, this spectrum does not exhibit a homogenous spread. That would be desirable, but does not indicate the steady-state power density, while zero indicates some peak values along the way. However, even this arrangement results in an improvement of almost 6 dB compared to the worst case of the 1010 signal. When the frequency modulation is performed on the 8B / 10B signal, the spectrum shown in FIG. 24 is obtained. Here, the maximum amplitude is −25.3 dB.
m, a further improvement of 5 dB results. Here, frequency modulation only fills the gap between the 8B / 10B signal spectral lines, but it is not suitable for spectral smoothing. Coding with a long pseudo-noise string having a pattern length of 128 bits results in a very uniform spectrum, exhibiting a maximum amplitude of -32.5 dBm as illustrated in FIG. This measurement has been confirmed in theoretical studies. Some changes are brought about by the definition and simplification of the theoretical model.

[0081]

As described above, the system and method for low-interference signal transmission according to the present invention provides a system in which the level of emitted noise is within the meaning of the current EMC standard and the corresponding impairment of the quality characteristics of the transmission. It is possible to form a digital transmission circuit, especially a non-contact rotary transmission circuit, and a non-contact high-speed data circuit, especially a very large open type device such as a computer X-ray tomography machine (CT scanner) Essential to the use of equipment designed for (means).

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating one embodiment of a system for transmitting low-interference signals according to the present invention.

FIG. 2 shows 190M at baseband in the same system.
FIG. 3 shows a noise spectrum of a typical transmission circuit with a baud.

FIG. 3 is a diagram showing a noise spectrum of a transmission circuit in which frequency modulation of a clock generator is performed in the same system.

Fig. 4 200M baud 1010P in the same system
It is a figure which shows a CM signal (upper graph) and a bit period signal (lower graph).

FIG. 5: 200M baud 1010- in the same system
FIG. 3 is a diagram illustrating a spectrum of a PCM signal at 9 to 1 GHz.

FIG. 6 is a diagram showing a 200M baud PCM signal having a 10,000100 pattern (upper graph) and a bit period signal (lower graph) in the same system.

FIG. 7 is a view showing a spectrum of 9 to 1 GHz of a 200 Mbaud PCM signal (10000100) in the same system.

FIG. 8 shows a standard M baud PCM signal (narrow graph) and a frequency-modulated bit clock signal (wide graph) at the illustrated center frequency of 100 MHz in the same system.
It is a figure which shows the 2009M baud PCM signal which separated the line distance by MHz.

FIG. 9 is a diagram showing an example of the 200M baud signal (upper graph) of FIG. 8 with the frequency-modulated bit clock signal (lower graph) in the same system.

FIG. 10 shows a peak amplitude of -36d in the same system.
200m baud PCM with Bm and line distance 1.56MHz
It is a figure which shows -PN7 spectrum (pseudo noise whose bit pattern length is 128).

FIG. 11 is a 200 Mbaud PCM-P having an amplitude of -60 dBm and a line distance of 6.1 KHz in the same system.
It is a figure which shows N15- spectrum (pseudo noise whose bit pattern length is 32768).

FIG. 12: 200M baud PCM-P having an amplitude of −54 dBm and a line distance of 1.5 KHz in the same system.
It is a figure which shows N17 spectrum (pseudo noise with a bit pattern length of 131072).

FIG. 13 is a diagram showing a state where random coding (upper three graphs) and decoding (lower three graphs) in the above-described system are realized by dedicated-OR linking of data provided with a pseudo-noise string.

FIG. 14 is a diagram showing controlled phase shifting means in the above system.

FIG. 15 shows a diagram of a 20
0M baud PCM reference frequency (narrow peak) and 10KHz
FIG. 7 is a diagram showing a spectrum (wide peak) of a phase-modulated signal of 6.28 rads in FIG.

FIG. 16 shows a diagram of a 20
FIG. 3 shows a 0M baud PCM reference frequency (narrow peak) and a frequency-modulated signal at 1 MHz (wide peak).

FIG. 17 is a diagram showing a plane frequency modulated signal in the above system.

FIG. 18 is a diagram showing a dual spectrum in the above system.

FIG. 19 FM at low frequency deviation in the same system
It is a figure showing an expansion spectrum.

FIG. 20 is a diagram showing an FM-PCM signal (upper cliff) and a bit clock signal having a lower frequency shift (lower graph) in the same system.

FIG. 21 is a diagram showing modulation by periodic regeneration in the above system.

FIG. 22 shows a frequency range from 9 to 1 GHz in the same system.
It is a figure which shows the 0M baud 1010PCM signal spectrum.

FIG. 23: 8B at 9 to 1 GHz in the same system
200M baud 1010 with / 10B coding
It is a figure showing a PCM signal spectrum.

FIG. 24: 9B to 1GHz 8B in the same system
200M baud 10 with / 10B coding and FM
It is a figure showing a 10-PCM signal spectrum.

FIG. 25 shows a 200M baud with pseudo random coding of 9 to 1 GHz in the same system.
It is a figure showing a PCM signal spectrum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitter 2 Transmission circuit (data channel) 3 Receiver 4 Modulator device 5 Controller device

Claims (36)

[Claims] 1. A transmitter (1), which can move with respect to each other, preferably via a line connection or a transmission circuit, in particular with a rotary transmitter via a contactless transmission circuit (2). A system for transmitting a signal, in particular a low-interference signal of a digital signal, to a receiver (3) which is spaced apart, comprising a signal to be transmitted by a modulator device (4) and a transmission in a transmitter (1). The output signal spectrum of the transmitter (1) is independent of the carrier signal of the means or the transmitter output signal, which may be anywhere in the transmission circuit (2), regardless of the modulation selected for signal transmission. A system for low jamming signal transmission characterized by being modulated by a spectral function so that the spectral power density of the transmitter output signal is reduced without increasing the bandwidth of the signal. 2. The transmitter output signal, regardless of the transmission period, wherein the signal to be transmitted or the carrier signal of the transmission means in the transmitter or the transmitter output signal is independent of the transmission period at any arbitrary point in the transmission circuit. 2. The system of claim 1 wherein said line spectrum is expanded and modulated in such a way that the average spectral power density is reduced by filling gaps between individual signal lines. 3. The system for transmitting low-interference signals according to claim 1, wherein a controller device (5) serves for controlling the modulator device (4). 4. The system for transmitting low-interference signals according to claim 1, wherein said transmitter (1) comprises a clock generator. 5. The system of claim 4, wherein the modulator device (4) substantially controls the clock generator to broaden the line spectrum. 6. The system of claim 5, wherein the modulator device (4) frequency-modulates a periodic frequency of the clock generator. 7. The system of claim 6, wherein said clock generator comprises a VCO as a frequency determining element. 8. The system as claimed in claim 7, wherein the controller device (5) regulates the VCO. 9. The modulator according to claim 1, wherein the modulator device (4) modulates a signal to be transmitted, in particular a digital signal, with frequency, phase or amplitude modulation. Low interference signal transmission system. 10. The transmitter device according to claim 1, wherein the modulator device (4) is located at any location along the carrier signal or transmission circuit (2) of the transmission means in the transmitter (1). 10. The system of claim 1, wherein the frequency or phase modulation is applied independently of the modulation technique chosen for signal transmission. 11. In the case of a pulse carrier signal or a pulse transmitter output signal of said transmitter (1), a modulator device (4) converts the signal defined by a signal generator additionally provided with individual signal ends. The system for transmitting low-interference signals according to any one of claims 1 to 10, wherein the system is moved or delayed in proportion to an earlier or later point in time. 12. The modulator device (4) comprising delay control means for analyzing the output signal of the transmitter or controlling a delay circuit which causes each of the movement or the delay. 12. The system for transmitting a low-interference signal according to claim 11. 13. The system according to claim 12, wherein said delay control means comprises a PLL means, and said delay circuit comprises a flip-flap circuit. 14. The system for transmitting low-interference signals according to claim 1, wherein the transmitter comprises a PLL means. 15. The system of claim 14, wherein the modulation change of the modulator device (4) is converted by a control range of the PLL means of the transmitter (1). 16. The low disturbance signal according to claim 1, wherein data coding with pseudo-random noise (noise) is performed in addition to the modulation by the modulator device (4). Transmission system. 17. A controller device (5) for said receiver (3).
Is provided so that the signal received by the receiver (3) in synchronism with the modulation by the modulator device (4) at least at any arbitrary location of the transmitter or the transmission circuit at least this additional Without modulation, each of the transmitter (1) and the transmission circuit (2) can be processed in synchronization with each other, and the receiver can operate the modulated signal or the receiver (1) or the transmission circuit (2). 17. Low interference according to one of the preceding claims, characterized in that each and said receiver are adapted to adapt to any implementation via another signal which can be used jointly. Signal transmission system. 18. An additional transmission circuit comprising: each of the transmitter (1) or the transmission circuit (2); and the transmitter (1).
Alternatively, it is arranged between each of the transmission circuits (2) and the receiver (3) for transmitting an additional synchronization signal for controlling the modulation of the receiver (3). 18. The system for transmitting a low-interference signal according to any one of 1 to 17. 19. A line, preferably in contact with and / or in particular contactless with a rotary transmitter, from a mutually movable transmitter (1) to a receiver (3) spaced apart therefrom. A method of transmitting low-interference signals of signals, in particular digital signals, via a transmission circuit (2), wherein the carrier signal of the transmission means in said transmitter (1) or any of the transmission circuits (2) is to be transmitted. Regardless of the modulation chosen for signal transmission, the transmitter output signal, which may be anywhere,
A method of low interference signal transmission characterized by a modulation performed by a modulator device so as to broaden the output signal spectrum of the transmitter (1) and thus reduce the power density in the spectrum of said transmitter output signal. 20. The method of claim 19, wherein reducing the average spectral power density is performed by filling gaps between the individual signal lines. 21. The method as claimed in claim 19, wherein the modulator device (4) is controlled by a controller device (5). [Contents of correction] 22. The method according to claim 19, wherein the transmitter comprises a clock generator. 23. The method for transmitting low-interference signals according to claim 22, characterized in that suitable control for line spectrum broadening by the modulator device (4) of the clock generator is provided. 24. Frequency modulation of said clock generator by said modulator device (4).
The method for transmitting low-interference signals as described above. 25. The system according to claim 2, wherein said clock generator comprises a VCO as a frequency determining element.
5. The method for transmitting a low-interference signal according to 4. 26. The method as claimed in claim 25, characterized in that the VCO is adjusted by the controller device (5). 27. The modulator device according to claim 19, wherein the modulator device subjects the signal to be transmitted, in particular a digital signal, to frequency, phase or amplitude modulation.
The method for transmitting a low-interference signal according to any one of the preceding claims. 28. The transmitter output signal, wherein the modulator device (4) may be located anywhere along the carrier signal or transmission circuit (2) of the transmission means of the transmitter (1). 28. The method of transmitting low-interference signals according to claim 19, wherein each of the phase modulations is applied with a modulation selected for signal transmission regardless of the modulation. 29. In the case of a pulse carrier signal or said transmitter (1) or a pulse transmitter signal, each of the modulator arrangements (4) has its own signal end by means of an additionally arranged modulation signal generator. 29. The method according to claim 19, further comprising moving or delaying the time earlier or later in proportion to the assumed signal.
The method for transmitting a low-interference signal according to any one of the preceding claims. 30. The modulator device (4) comprising a delay control means for performing a division of a transmitter output signal and a control of a delay circuit which causes movement and delay. 30. The method of transmitting a low-interference signal according to claim 29. 31. The method of claim 30, wherein said delay control means comprises a PLL means, and said delay circuit comprises a flip-flop circuit. 32. A method for transmitting low-interference signals according to claim 19, wherein said transmitter (1) comprises PLL means. 33. The apparatus according to claim 19, wherein the modulation variation of the modulator device is converted by a control range of a PLL means of the transmitter. Low interference signal transmission method. 34. The method according to claim 19, wherein the data coding is performed by pseudo-random noise in addition to the modulation by the modulator device.
3. The method for transmitting a low-interference signal according to claim 3. 35. A controller device (5) in said receiver (3).
Is arranged and received by the receiver (3) at any position of the transmitter (1) or the transmission circuit (2) in synchronization with the modulation by the modulator device (4). The transmitted signal can be processed synchronously between the transmitter (1) and the transmission circuit (2), respectively, without at least this additional modulation, and the receiver (3) can be the modulated signal or the receiver. 35. Control according to any one of claims 19 to 34, wherein the control is adapted to adapt to any implementation via another signal which can be used jointly by each of the transmission circuits and the receiver. The method for transmitting low-interference signals as described above. 36. A receiver disposed between each of said transmitter (1) or transmitter circuit (2) and said receiver (3),
An additional synchronization signal is transmitted via the control signal to control each of the transmitter (1) or the transmission circuit (2) and the receiver (3).
6. The method for transmitting a low-interference signal according to any one of the items 5 to 5.