JPH0746797B2 - Digital signal transmission method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal transmission method for transmitting a digital signal in a multipath transmission line such as wireless transmission in an urban area.

2. Description of the Related Art In recent years, even in the field of mobile communication, digitization is progressing due to improvement of confidentiality, sophistication of communication, and compatibility with peripheral communication networks. However, in urban areas where such demand is considered to be most concentrated, communication quality is significantly deteriorated due to multipath due to reflection and diffraction by buildings and other structures. In the case of digital transmission, if the propagation delay time difference between the waves forming the multipath cannot be ignored with respect to the data time slot, the waveform error and the tracking failure of the synchronous system will significantly deteriorate the code error rate characteristic.

Hereinafter, an example of the above-described conventional digital signal transmission method will be described with reference to the drawings.

FIG. 12 shows the phase transition of the transmission signal of the conventional digital signal transmission method. T indicates one time slot of data. When the data is 1, the phase transitions by 180 °,
When the data is 0, no phase transition occurs. This signal format is called differentially encoded binary phase modulation.

To detect such a transmission signal, for example, differential detection having a delay line of one time slot can be performed.
Now, let us consider, as a typical example of multipath, what happens to the detection output signal under the multipath of two waves having a propagation delay time difference τ that cannot be ignored compared to time slots. In addition, the wave that precedes in time is a direct wave,
The delayed wave is called the delayed wave.

FIG. 13 is a diagram for explaining what a detection output signal looks like when a transmission signal as shown in FIG. 12 is subjected to delay detection under a two-wave multipath. Figure 13 (a) shows
This shows the phase transition of the direct wave. On the contrary,
The phase transition of the delayed wave delayed by the propagation delay time difference τ is
It becomes like FIG. 13 (b). The detection output at a certain time point is the vector inner product of the combined phase of the two waves at that time and the combined phase of the two waves one time slot before. For example, in FIG. 13 (c), the detection output of the section B is 2 at the time of B '.
It is the value of the vector inner product of the wave synthesis phase and that of B.

FIG. 14 shows the combined phase of the direct wave and the delayed wave in order to obtain the detection output at each time point A to C.
The amplitude ratio of the direct wave and the delayed wave was ρ, and the phase difference was α. From FIG. 14, the detection output at each time point A to C in FIG. 13 (c) is as follows.

A: undefined B: 1 + ρ ² + 2ρ cosα C: undefined In sections A and C, the data values of the previous and subsequent time slots are undefined. After differential detection, a low-pass filter is usually inserted to remove unnecessary noise components, so the final detection output signal waveform is shown in Fig. 13 (c).
The waveform of the solid line is filtered, and the waveform becomes as shown by the dotted line of FIG. 13 (c), which constitutes a part of the eye pattern. By the way, when ρ is close to 1 and α is around 180 °, the detection output in the section B, which is an effective detection output, becomes almost zero. Therefore, the eye is closed and the code error rate characteristic deteriorates. Further, at this time, since the invalid detection output of the sections A and C is much larger than the valid detection output of the section B,
The eye greatly fluctuates in the time axis direction, the reproduced clock cannot follow, and the code error rate further deteriorates. (For example, Onoe et al., "Code Error Rate Characteristic in Rayleigh Fading with Propagation Delay Time Difference", IEICE Tech.
8, 1982, or Takai et al., “Analysis of Instantaneous Code Errors Due to Multipath Propagation and Error Generation Mechanism Based on Bit Synchronous System”, IEICE Technical Report, CS83-158, 1984) Problems to be Solved by the Invention In the above method, waveform distortion due to multipath is significant as described above, and the code error rate is significantly degraded. In particular, examining the relationship between the signal S / N ratio and the error rate, there is a region where the error rate does not decrease even if the S / N ratio is improved. Such a code error is called an irreducible error. Due to such so-called irreducible errors, the actual data transmission rate in urban areas is greatly limited, and high-speed transmission is impossible.

In view of the above problems, the present invention provides a digital signal transmission method capable of high-speed digital transmission in a multi-pulse transmission line such as an urban area.

Means for Solving the Problems In order to solve the above-mentioned problems, the digital signal transmission method of the present invention divides each time slot of data into a second half of the first half at a plurality of ratios, and divides the first half and the second half. Between the portions, there is one kind or a plurality of kinds of angle-dependent phase transitions, and the direction of the phase transitions is in accordance with an arbitrary sequence having an arbitrary period, and the phase transition in an arbitrary time slot and a predetermined The phase transition and the phase transition in the time slot after the time slot have the same size and direction, and the ratios of the first half part and the second half part indicating the transition position of the phase transition are also equal, and are separated by the predetermined time slot. Further, a signal having information to be transmitted in the phase difference between the first half portion and the second half portion of both of these time slots is used as one transmission signal.

Action The present invention, by using the transmission signal as described above,
When performing differential detection, two types of effective detection outputs can be obtained for each time slot. Then, due to one kind of diversity effect by combining these outputs, the code error rate under multipath is significantly improved. Further, in each time slot, two different types of effective detection output sets can be obtained depending on the type of the phase transition angle, the type of the ratio of the first half part and the second half part, and whether the phase transition direction is the advanced phase or the delayed phase. Therefore, burst errors are reduced, error correction can be simplified, and the code error rate under multipath is further improved. Due to the effects as described above, digital transmission at a higher speed than ever can be performed on a multipath transmission line.

Embodiment A digital signal transmission method according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a phase transition diagram showing a phase transition of a transmission signal of a digital signal transmission method according to the first embodiment of the present invention.
The transmission signal of the digital signal transmission method according to the first embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, one time slot of data is divided into a first half portion and a second half portion. The time of one time slot is shown as T, the first half time T ₁₁ , T ₂₁ , T ₃₁ , T ₄₁ , and the second half time T ₁₂ , T ₂₂ , T ₃₂ , T ₄₂ . Then, there is always a phase transition of the same magnitude as indicated by φ between the first half portion and the second half portion. The direction of these phase transitions, that is, whether the phase is the advanced phase or the delayed phase, must be a series having a certain period when the advanced phase and the delayed phase are viewed as a series of binary numbers. However, the series can be any series. That is, in FIG. 1, the positive phase axis may be either a phase advance or a phase delay, but if it is a phase advance, it will be like "phase advance, phase advance, phase advance, phase delay". An example in which the cycle is 4 time slots is shown. Also, the ratio of the first half and the second half, T ₁₁ : T ₁₂ , T ₂₁ , T ₂₂ , T ₃₁ , T ₃₂ or T ₄₁ : T.
There are four kinds of ₄₂ in this example, but any kind of ratio can be selected. Note that some of them may overlap. However, as shown in FIG. 1, the phase transition directions in both time slots separated by n time slots and the ratio of the first half and the second half must be equal. Therefore, n must be greater than or equal to the number of types of pairs of ratio and transition direction. Of course, n is a natural number. Also,
The phase shift amount φ may be arbitrary.

The location of the phase transition in a time slot and the location of the phase transition in the time slot after n time slots are
Since the ratios of the first half and the second half of both time slots are equal, they are in the same position in each time slot. Further, the phase difference between the first half portion and the second half portion of both time slots is equal because the phase transitions in both time slots are in the same amount and in the same direction. In FIG. 1, for example, the phase difference between the third time slot and the (n + 3) th time slot is θ as shown in the figure, and the location of the phase transition is at the same position in each time slot. Digital information is transmitted according to the value of the phase difference θ between the time slots separated by n time slots. For example, if a two-phase system of 0 ° and 180 ° is used as a possible value of θ, 1-bit information is transmitted by assigning 0 and 1 correspondingly. Also,
If a four-phase system of 0 °, 90 °, 180 °, 270 ° is used as θ,
Two bits of information are transmitted. Further, as the value of θ, 0 °, 45 °, 90 ° ... 8-phase system, similarly, 0 ° ,, 2.5
Those with multi-phase powers of 2 such as 16-phase systems of °, 45 °, 67.5 °, etc., or those that use only some of the above angles,
Further, it may be a multi-phase one that is not a power of 2 and one that the interval of possible values of θ may be constant, and the value of θ may be any value as long as the value corresponds to the transmitted information. .

As described above, the phase transition of the transmission signal of the digital signal transmission method of the first embodiment of the present invention is T ₁₁ , T ₁₂ , T ₂₁ , T ₂₂ ,
There are various ones depending on the values of T ₃₁ , T ₃₂ , T ₄₁ , T _42, ..., φ, θ, n and the sequence of the direction of the phase transition in the time slot. Examples are shown in FIGS. 2 to 4 below. Indicates.

Fig. 2 shows that n = 4 and φ = 90 °, the ratio of the first half and the second half is T ₁₁ : T ₁₂ and T ₂₁ : T ₂₂ , and the transition direction sequence is "advance, advance, In the case of "slow, slow" or "slow, slow, advance, advance", an example of the phase transition of the transmission signal that transmits 1-bit data for one time slot corresponding to θ = 0 °, 180 ° is shown. There is.

Similar to the case of FIG. 2, FIG. 3 shows that n = 4 and φ = 90 °, and the ratio of the first half part to the second half part is T ₁₁ : T ₁₂ and T ₂₁ : T ₂₂ . The sequence corresponds to θ = 0 °, 180 ° when “advance, advance, slow, slow” or “slow, slow, advance, advance”,
An example of phase transition of a transmission signal for transmitting 1-bit data for one time slot is shown. In the transmission signal of the digital signal transmission method of the present invention, when n is 2 or more, the phase difference between the first half and the second half of adjacent time slots, to be exact, the initial phase difference can be freely selected. The initial phase difference in the case of FIG. 3 deviates from the initial phase difference in the case of FIG. 2 by 45 ° or 135 °.

In Fig. 4, n = 4 and φ = 45 °, the ratio of the first half and the second half is T ₁₁ : T ₁₂ and T ₂₁ : T ₂₂ , and the transition direction sequence is "advance, advance, When "slow, slow" or "slow, slow, advance, advance", corresponding to θ = 0 °, 90 °, 180 °, 270 °, (0,0), (1,0), ( An example of phase transition of a transmission signal for transmitting 2-bit data for one time slot, such as 1,1) and (0,1) is shown. In this case, as in the case of offset four-phase phase modulation, for example, θ = 0 °, 90 °,
It may be one that takes only part of the angle of the four-phase system, such as 270 °.

Next, the reason why the digital signal transmission method of the present invention is strong against multipath distortion will be described as an example.

In the following description, as an example of the transmission signal of the digital signal transmission method of the present invention, θ = 0 °, 180 °, that is, a two-phase system transmission signal as shown in FIG. 2 or 3 will be used. In addition, as a multipath model, a typical 2
Consider a wave model. Direct wave that precedes in time,
The delayed wave is called the delayed wave.

The digital signal transmission method of the present invention is detected by differential detection using a delay line of n time slots. An example of the structure of the detection circuit is shown in FIG. However, in FIG. 5, 1 is an input terminal, 2 is a multiplier, 3 is an n time slot delay device, 4 is a reduction pass filter, and 5 is a detection output terminal.

FIG. 6 is a diagram for explaining what a detection output signal looks like when these transmission signals are detected by the detection circuit of FIG. 5 under a two-wave multipath. Figure 6 (a)
FIG. 4 shows the phase transition of an arbitrary time slot of a direct wave and a time slot after the n time slots. The locations of the phase transitions in both time slots are at the same position in each time slot, and the direction and size of each phase transition are the same, and the size is indicated by φ. On the other hand, the phase transition of the delayed wave delayed by the propagation delay time difference τ which cannot be ignored compared to the time slot is as shown in FIG. 6 (b). The detection output at a certain time point is a vector inner product of the combined phase of the two waves at that time and the combined phase of the two waves n time slots before. For example, in FIG. 6 (c), the detection output in the section B is
It is the value of the vector inner product of the two-wave composite phase for B'and that for B.

FIG. 7 shows a combined phase of the direct wave and the delayed wave in order to obtain the detection output at each time point A to E.
The amplitude ratio of the direct wave and the delayed wave was ρ, and the phase difference was α. Further, the phase axes of FIGS. 6A and 6B may be positive or may be in the advanced phase, but are set in the advanced direction. From FIG. 7, when the waveform is not deformed by the low-pass filter 4, or when the cutoff frequency is sufficiently higher than the data transmission rate, the detection output at each time point A to E in FIG. become that way.

A: undefined B: 1 + ρ ² + 2ρ cosα ・ ・ ・ C: 1 + ρ ² + 2ρ cos (α ± φ) ・ ・ ・ D: 1 + ρ ² + 2ρ cos ・ ・ ・ E: undetermined In the sections A and E, time slots before and after respectively It is undefined depending on the data value of. Depending on the values of ρ and α, even if the detection signal in any of the sections B, D and C becomes zero, the other does not become zero. The compound symbols in the equation are + when the phase transition φ is late and − when it is advanced. For example, in FIG. 6 or 7, since φ is a phase advance, the compound double sign of the equation is − at this time. That is, θ
Even in the time slot in which is delayed, the above description is exactly the same, except that the compound of the formula becomes +.

In practice, the cutoff frequency of the low-pass filter 4 is selected low enough to prevent intersymbol interference. Therefore, the detection output signal after passing through the low-pass filter 4 is as shown in FIG.
The waveform of the solid line is filtered to form a part of the eye pattern as shown by the dotted line in FIG. 6 (c). As described above, the sections B and D and the section C generate complementary detection outputs, so that the eye does not close. Further, at least one of these effective detection outputs does not become smaller than the ineffective detection output in the section A or E, so that fluctuations of the eye in the time axis direction are reduced and the code due to the poor tracking of the reproduction clock is reduced. There is little deterioration in the error rate.

As described above, the digital signal transmission method of the present invention is less susceptible to waveform distortion due to multipath due to a kind of diversity effect by combining different detection outputs of the sections B and D and the section C. Furthermore, since there are multiple types of ratios of the first half part and the second half part of the time slot that indicate the location of the phase transition, the section showing the effective detection output.
The composition ratios of B, C, and D exist only for the same kind. When this component ratio changes, the error rate characteristic with respect to the propagation delay time difference τ changes. In particular, by intentionally changing the ratio of the first half portion and the second half portion of the time slot from 1: 1, either the section B or the section D and the section C are provided for a multipath transmission line having a longer delay time difference. It can be made to exist and the error rate characteristic can be improved (see IEICE technical report SAT86-23). This means, conversely, that higher-speed transmission can be performed on the same transmission line (with a constant delay time difference). On the other hand, since the detection output of the section C is different due to the difference in the phase transition direction within the time slot, even if the error rate of the time slot having a certain ratio and a certain transition direction deteriorates under a specific multiplex wave condition, The error rate of the time slot other than this ratio or the transition direction does not necessarily deteriorate. That is, it is possible to prevent a burst error from occurring in the transmitted data string, simplify error correction, and improve the error rate characteristic. As described above, the code error rate characteristic in the multipath transmission line is remarkably improved as compared with the conventional method, and high-speed digital transmission becomes possible.

In this description, a two-phase system transmission signal such as θ = 0 °, 180 ° as shown in FIG. 2 or 3 has been described as an example, but transmission using another value as the value of θ. The bit error rate characteristic of a signal is remarkably improved by the same principle. For example, when θ is a multi-phase system such as a 4-phase system or an 8-phase system, a 90 ° phase shifter is further connected to the output of the 1-time-slot delay device 3 in FIG. 5, and this output signal is used as a reference signal for quadrature. It is necessary to perform differential detection on the axis as well. However, although the configuration of the detection circuit becomes complicated, the detection output of each detection axis is exactly the same as the above description.
The code error rate characteristic is remarkably improved due to a kind of diversity effect which has effective detection outputs of a kind and combines them. Then, these two types of effective detection output sets exist only in the ratio of the first half part and the second half part and in the type of the transition direction, and the burst error is reduced and the code error characteristic is improved. It should be noted that the transmission rate can be doubled or tripled with respect to the same time slot length by using multi-valued 4-phase and 8-phase, and a good error rate characteristic can be obtained in higher speed transmission. Can be demonstrated.

That is, the digital signal transmission method of the first embodiment of the present invention using the transmission signal having the phase transition as shown in FIG. 1 is T ₁₁ , T ₁₂ , T ₂₁ , T ₂₂ , T ₃₁ , T ₃₂ , T _32. , T ₄₁ , T ₄₂ …, φ,
It is a kind of diversity by combining two effective detection outputs that are different from each other regardless of the difference between them and the sequence of the phase transition direction in each time and value of θ, n. Due to the effect and burst error mitigating effect of having two or more types of effective detection output pairs depending on the time slot, the code error rate characteristic is significantly improved over the conventional method in the multipath transmission line, and high speed It enables digital transmission.

A digital signal transmission method according to the second embodiment of the present invention will be described below with reference to the drawings.

FIG. 8 is a phase transition diagram showing the phase transition of the transmission signal of the digital signal transmission method of the second embodiment of the present invention. Less than,
A transmission signal of the digital signal transmission method according to the second embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 8, as in the embodiment of FIG. 1, one time slot of data is divided into a first half portion and a second half portion.
The time of one time slot is T, the time of the first half is T ₁₁ , T
₁₂ , T ₃₁ , T ₄₁ , and the time of the latter half are shown as T ₁₂ , T ₂₂ , T ₃₂ , and T ₄₂ . And between the first half and the second half, φ
There is always a phase transition as shown by _{1 to} φ ₄ . The direction of these phase transitions, that is, whether the phase is the advanced phase or the delayed phase, must be a series having a certain period when the advanced phase and the delayed phase are viewed as a series of binary numbers. However, the series can be any series. That is, in FIG. 8, the positive phase axis may be either advanced or delayed, but if it is advanced, it will be like "advanced, advanced, advanced, delayed". An example in which the cycle is 4 time slots is shown. Also, the ratio of the first half to the second half, T ₁₁ : T ₁₂ , T ₂₁ , T ₂₂ , T ₃₁ : T
₃₂ or T ₄₁ : T ₄₂ are four kinds in this example, but any kind of ratio can be selected. Note that some of them may overlap. The above is exactly the same as in the first embodiment.

The difference from the first embodiment is that there are four types of phase transitions in the time slot, which are φ ₁ , φ ₂ , φ ₃ , and φ ₄ in this example. Note that the number of types of phase transition amounts is four in this example, but can be selected arbitrarily and some may overlap. However,
As shown in FIG. 8, n time slots apart,
The amount of phase transition, the direction of phase transition, and the ratio of the first half part to the second half part in both time slots must be equal. Therefore, n must be greater than or equal to the number of types of pairs of phase transition amount, phase transition direction, and ratio. Of course, n is a natural number.

The location of the phase transition in a time slot and the location of the phase transition in the time slot after n time slots are
Since the ratios of the first half and the second half of both time slots are equal, they are in the same position in each time slot. Further, the phase difference between the first half portion and the second half portion of both time slots is remarkable because the phase transitions in both time slots are in the same amount and in the same direction. This is exactly the same as in the first embodiment. Is. In FIG. 8, for example, the phase difference between the third time slot and the (n + 3) th time slot is θ as shown in the figure, and the location of the phase transition is at the same position in each time slot. Similar to the first embodiment, digital information is transmitted according to the value of the phase difference θ between the time slots separated by n time slots. For example, if a two-phase system of 0 ° and 180 ° is used as a possible value of θ, 1-bit information is transmitted by assigning 0 and 1 correspondingly. Also, as θ, 0 °, 90 °, 180 °, 270 °
If the four-phase system is used, 2-bit information is transmitted. Furthermore, as the value of θ, 8-phase system of 0 °, 45 °, 90 °,
Similarly, 0 °, 22.5 °, 45 °, 67.5 ° ... 16 phase system etc. 2
It is possible to use a power-of-power polyphase system, one that uses only some of the above angles, one that is not a power-of-two power, and one that the interval of possible values of θ is not constant. The value of may be any value as long as the value corresponds to the information to be transmitted.

As described above, the phase transition of the transmission signal of the digital signal transmission method of the second embodiment of the present invention is T ₁₁ , T ₁₂ , T ₂₁ , T ₂₂ ,
T ₃₁ , T ₃₂ , T ₄₁ , T ₄₂ ……, φ ₁ , φ ₂ , φ ₃ , φ ₄ …,
There are various types depending on the value of θ, n and the sequence of the direction of the phase transition within the time slot, and examples are shown in FIGS. 9 to 11 below.

FIG. 9 shows n = 4, φ ₁ = 45 °, φ ₂ = 135 °, the ratio of the first half and the second half is T ₁₁ : T ₁₂ and T ₂₁ : T _22. , "Advance, Advance, Slow, Slow" or "Slow,
An example of phase transition of a transmission signal for transmitting 1-bit data for one time slot is shown corresponding to θ = 0 ° and 180 ° when “slow, advance, and advance”.

FIG. 10 shows n = 4, φ ₁ = 45 °, φ as in FIG.
₂ = 135 °, the ratio of the first half to the second half is T ₁₁ : T ₁₂ and T
₂₁ : Two kinds of T ₂₂ and the series of transition directions are "advance, advance, slow,
When "slow" or "slow, slow, advance, advance", θ = 0 °, 180 °
Corresponding to, an example of phase transition of a transmission signal for transmitting 1-bit data for one time slot is shown. In the transmission signal of the digital signal transmission method of the present invention, n
Is 2 or more, the phase difference between the first half and the second half of adjacent time slots, to be exact, the initial phase difference can be freely selected. The initial phase difference in the case of FIG. 10 is
It deviates from the initial phase difference in the case of FIG. 9 by 45 ° or 135 °.

In FIG. 11, n = 4, φ ₁ = 45 °, φ ₂ = 135 °, and the ratio of the first half and the second half is T ₁₁ : T ₁₂ and T ₂₁ : T ₂₂ .
The sequence of transition direction is "advance, advance, slow, slow" or "slow,
Slow, advance, advance ", corresponding to θ = 0 °, 90 °, 180 °, 270 °, (0,0), (1,0), (1,1), (0, 1)
As described above, an example of phase transition of a transmission signal for transmitting 2-bit data for one time slot is shown. In addition,
In this case, as in the case of offset 4-phase modulation, for example, θ
It may be one that takes only part of the angle of the four-phase system, such as = 0 °, 90 °, 270 °.

Also in the second embodiment, as in the first embodiment, the location of the phase transition in a certain time slot and the location of the phase transition in the time slot after the n time slots are at the same position in the time slot. Yes, and the phase transitions in both time slots are in the same amount and in the same direction. Therefore, the ninth
Taking the two-phase transmission signal shown in FIG. 10 or FIG. 10 as an example, by using the detection circuit shown in FIG. The detection waveform shown in FIG. 6 (c) can be obtained in the second embodiment in exactly the same manner as described with reference to FIG.
The detection outputs of the sections B to D are the same as those shown in the equations. However, the value of φ is the amount of phase transition within that time slot, and for example, in the example of FIG. 8, any one of φ ₁ to φ ₄ is entered. As in the embodiment of FIG. 1, the compound symbols in the equation are + when the phase transition φ is late and-when the phase is advanced. As in the first embodiment, even if the detection signal in any of the sections B, D and C becomes zero, the other does not become zero due to the values of ρ and α.

As described above, also in the second embodiment, the digital signal transmission method of the present invention uses a multi-path waveform due to a kind of diversity effect by combining different detection outputs of the sections B and D and the section C. Not susceptible to distortion. Since there are multiple types of ratios of the first half part and the second half part of the time slot that indicate the location of the phase transition, there are multiple component ratios of the sections B, C, and D that show the effective detection output. Further, not only the detection output in the section C differs due to the difference in the phase transition direction in the time slot, but in the case of the second embodiment, there are a plurality of values of φ, so that the detection output in the section C is large. There are types. Therefore, even if the error rate of a time slot having a certain ratio, a certain transition direction, and a certain transition amount is deteriorated under a specific multiplex wave condition, the error rate of a time slot other than this ratio, the transition direction, or the transition amount is not necessarily deteriorated. Without doing so, burst errors are less likely to occur in the transmitted data string, and error correction can be simplified.

In this description, as in the first embodiment, the two-phase system transmission signal such as θ = 0 °, 180 ° as shown in FIG. 9 or FIG. 10 has been described as an example. The bit error rate characteristic is remarkably improved by a completely similar principle even in a transmission signal in which other values are used as. For example, when θ is a multi-phase system such as a 4-phase system or an 8-phase system, a 90 ° phase shifter is further connected to the output of the 1 time slot delay device 3 in FIG.
It is necessary to perform differential detection on the orthogonal axis using this output signal as a reference signal. However, although the configuration of the detection circuit becomes complicated, the detection output of each detection axis has exactly two types of effective detection outputs, just like the above description, and due to a kind of diversity effect by combining both. , The bit error rate characteristic is significantly improved. Then, these two types of effective detection output groups are present only in the types of the group of the phase transition amount, the phase transition direction, and the ratio of the first half portion and the second half portion, and the burst error is reduced. It should be noted that, as in the case of the first embodiment, it is possible to increase the transmission rate to 2 times or 3 times for the same time slot length by making multi-values of 4 phases and 8 phases. A good error rate characteristic can be exhibited in high-speed transmission.

That is, the digital signal transmission method of the second embodiment of the present invention using the transmission signal having the phase transition as shown in FIG. 8 is T ₁₁ , T ₁₂ , T ₂₁ , T ₂₂ , T ₃₁ , T _32. , T ₄₁ , T ₄₂ …,
φ ₁ , φ ₂ , φ ₃ , φ _4, ..., θ, n values can be freely selected,
Regardless of the difference in their respective values, all have a kind of tie diversity effect by synthesizing two kinds of effective detection outputs different from each other. Further, by having a set of two or more types of effective detection outputs that can be selected more freely than the first embodiment by the value of φ, a burst error mitigation effect can be obtained, and a code error can be further reduced in a multipath transmission line. The rate characteristic is significantly improved, and high-speed digital transmission becomes possible.

As described above, according to the present invention, each time slot of data is divided into a first half portion and a second half portion at a plurality of types of ratios, and one or a plurality of types of angle magnitudes are provided between the first half portion and the second half portion. And the direction of the phase transition follows an arbitrary sequence having an arbitrary period, and the phase transition in an arbitrary time slot and the phase transition in a time slot after a predetermined time slot are different from each other. The first half and the second half of each of these time slots are equal in size and direction, and the proportions of the first half and the second half indicating the transition position of the phase transition are also equal, and are separated by the predetermined time slot. By using a signal having information to be transmitted in the phase difference between
High-speed digital transmission becomes possible in the multipath transmission line.

In particular, the present invention contributes to the improvement of characteristics in a multipath transmission line, the magnitude of the phase transition of a predetermined angle in a time slot, and the parameter of the position in the time slot represented by a predetermined ratio. There are multiple types of combinations, each of which can be arbitrarily selected, and it is possible to set optimal parameters according to other constraint conditions such as transmission path conditions. Faster,
Higher quality transmission is possible.

[Brief description of drawings]

FIG. 1 is a phase transition diagram of a transmission signal of a digital signal transmission method according to the first embodiment of the present invention, FIGS. 2 to 4 are phase transition diagrams of an example of the transmission signal, and FIG. Alternatively, FIG. 6 or 7 is a block diagram of an example of a detection circuit corresponding to the transmission signal of the digital signal transmission method of the present invention as shown in FIG. 3 or 9 or 10. FIG. 8 is a waveform diagram of a detection output signal and a vector diagram showing a composite phase of multipath waves for explaining that the digital signal transmission method of FIG. 1 is resistant to multipath distortion. FIG. 8 is a digital signal transmission in the second embodiment of the present invention. FIG. 9 to FIG. 11 are phase transition diagrams of an example of the transmission signal of the method, FIG. 12 is a phase transition diagram of the transmission signal of the conventional digital signal transmission method, FIG. 13 and FIG. Figure 14 shows that the conventional digital signal transmission method has multipath distortion. FIG. 6 is a waveform diagram of a detection output signal and a vector diagram showing a composite position of multipath waves, which is vulnerable to. 1 ... input terminal, 2 ... multiplier, 3 ... n time slot delay device, 4 ... low pass filter, 5 ... detection output terminal.

Claims (5)

[Claims] 1. A transmission device for transmitting digital data, wherein each time slot of data is divided into a first half portion and a second half portion at a ratio of a plurality of types, and one or a plurality of types are provided between the first half portion and the latter half portion. The phase transition has an angle magnitude, and the direction of the phase transition follows an arbitrary sequence having an arbitrary period, and the phase transition in an arbitrary time slot and the phase transition in a time slot after a predetermined time slot. Phase transitions have the same magnitude and direction,
And, the ratio of the first half part and the second half part indicating the transition position of the phase transition is also equal, and separated by the predetermined time slot, between the first half part and the second half part of each of these two time slots. A digital signal transmission method, wherein a transmission signal having information to be transmitted in a phase difference is used, and detection is performed by differential detection using a delay line capable of delaying the signal by the predetermined time slot. 2. The digital signal transmission method according to claim 1, wherein the phase difference is either 0 or 180. 3. The digital signal transmission method according to claim 1, wherein the phase difference is any of 0, 90, 180, and 270. 4. The digital signal transmission method according to claim 1, wherein the phase difference is one of angles obtained by dividing 360 into eight. 5. The digital signal transmission method according to claim 1, wherein the phase difference is one of angles obtained by dividing 360 into 16.