JP2000032068A - Waveform detection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a signal with use of its periodicity by discriminating whether or not the logical value of a demodulation signal is different from its reference level, shifting back and forth the position of an estimated window, setting the shift extent and width of the estimated window based on the singularity of a demodulation waveform, evaluating the logical change point of the demodulation signal based on the said shift extent and width and deciding whether the waveform of a modulation signal is proper or not. SOLUTION: A FLEX decoder 40 includes a data decoding part 41 which converts the output of an AC conversion part 30 into a signal format that is prescribed by a FLEX-TD standard and outputs the signal format after correcting it in every block of 32-bit width. A waveform detection part 42 and a battery saving part 43 are added to the decoder 40. The part 42 decides whether or not a proper receiving signal is allocated to a high-grade radio call system by paying attention to the modulating unit periodicity of a binary or quadruple FSK signal. The part 43 stops the unnecessary operations of circuits in response to the output of the part 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex modulation system (for example, a ^2n- valued FSK) which can have ²ⁿ (n is a positive integer) discrete values (hereinafter, ^2n- values). And the like, and a method and apparatus for detecting a waveform used when demodulating a signal modulated by the above method.

[0002]

2. Description of the Related Art For example, in "FLEX-TD" used in an advanced radio paging system, message information addressed to a specific ID delivered to a base station via a public line network or the like is transmitted from the base station to the ID. To a receiver (for example, a pager) having a radio channel. By using both binary FSK and quaternary FSK, the channel capacity of 1600 bps is doubled to 3200 bps to 6400 bps, and a message with a large number of characters can be transferred. ing.
FSK is an abbreviation of frequency shift keying, and is a kind of frequency modulation method in which an output frequency is switched between predetermined values by a modulation wave. Binary (or binary) FSK for two values, quaternary (or Q; quad) for four values
rature) FSK. It should be noted that an 8-valued value, a 16-valued value, a 32-valued value, or more values may be used, but the value is still 2 ⁿ in principle.

As shown in FIG. 8, a signal modulated by the quaternary FSK has a total of four frequency components (, and) separated by shifts Δf1 and Δf2 on the frequency axis with respect to the carrier frequency fc. , And four pieces of information from 0 to 3 (“0” in binary)
0 "," 01 "," 10 "," 11 "), and a signal modulated by the binary FSK includes only one of these, and two information of 0 and 1 ( "0", "1") can be represented by a binary number.
The first bit of the binary representation information in the value FSK is x, and the second bit is y, and is expressed in the form of "xy".

Here, in FLEX-TD, "R
According to “CR STD-43” (a standard developed by the Radio Industries and Businesses Association), fc is defined as a predetermined frequency in a 280 MHz band, Δf1 is defined as 1.6 kHz, Δf2 is defined as 4.8 kHz, and each frequency component is defined. Are defined as shown in Table 1.

[0005]

[Table 1]

[0006] A FLEX-TD standard receiver uses a binary FSK.
When the signal is demodulated, either "0" or "1" information is obtained. When the quaternary FSK signal is demodulated, "00",
One of the information “01”, “11”, and “10” is obtained. Comparing the two, the baud rate (the unit of the modulation speed indicating how many times a second is modulated) is the same, but the amount of information contained in one modulation unit (hereinafter sometimes referred to as “symbol”) is 2 The quaternary FSK is twice (ie, n times) the value FSK.

In an information transmission system using such a multiplex modulation scheme, for example, the above-mentioned advanced radio paging system, a portable receiver is often used.
From the viewpoint of suppressing battery consumption and improving the elimination performance of a received signal including an error, it is required to start a receiving operation only when an appropriate signal is received. It is necessary to correctly recognize the signal assigned to the radio paging system from. Therefore, the waveform detection circuit is effective.

Therefore, conventionally, the following waveform detection method has been used focusing on the periodicity of the modulation unit of the binary FSK signal. FIG. 9 is a demodulated waveform diagram of the binary FSK signal. This waveform is obtained by associating two frequency components (see FIG. 9 and FIG. 9) of the binary FSK signal with a first potential level and a second potential level, respectively. For example, assuming that the amplitude (peak to peak) of the waveform is a [V], the first potential level is + a / 2 [V] and the second potential level is based on the center level (0 [V] for convenience). The potential level is-
a / 2 [V], and if the margin is ignored, the frequency component information "0" is represented in the range of 0 [V] to -a / 2 [V], and the frequency component information "1" is 0 [V]. V] to + a /
It will be expressed in the range of 2 [V].

That is, the demodulated waveform of an appropriate binary FSK signal containing information of "0" is always 0 [V] to -a / 2 [V].
And the same waveform including the information of "1" always falls within the range of 0 [V] to + a / 2 [V], so that the information changes ("0" → "1", "1"). An appropriate signal waveform in the case accompanied by “0”) maintains the same periodicity corresponding to a half cycle (Ta) of a sine curve for each modulation unit (symbol).

Therefore, if the information change is detected again at the time (b) after the time corresponding to the above Ta from the time of detecting the information change (a), the baud rate corresponding to the signal assigned to the radio paging system is determined. Since the predetermined periodicity is maintained, it is possible to correctly determine that the received signal is an appropriate received signal that does not include an error. For example, the receiving operation can be started with the battery saving function turned off.

[0011]

However, the above-described conventional waveform detection method can be applied to a binary multiplex modulation signal, but cannot be applied to a quaternary or higher multi-value multiplex modulation signal. For example, in the above-mentioned advanced radio paging system using both binary FSK and quaternary FSK, it is not possible to reliably eliminate a reception signal containing an error, and to effectively save battery power. Also cannot be performed.

FIG. 10 is a demodulated waveform diagram of a quaternary FSK signal. This waveform is similar to the binary FSK signal described above,
The four frequency components (and in FIG. 9) of the value FSK signal correspond to a first potential level, a second potential level, a third potential level, and a fourth potential level, respectively. For example, assuming that the amplitude of the waveform is a [V], the first potential level is + a / 2 [V] and the second potential level is + a /, based on the center level (0 [V] for convenience). 6 [V], the third potential level is -a / 6
[V], the fourth potential level becomes -a / 2 [V], and if the margin is ignored, the frequency component information "00" becomes-
The frequency component information "01" is represented in the range of -a / 3 [V] to 0 [V], and the frequency component information is represented in the range of a / 2 [V] to -a / 3 [V]. “11” is 0 [V]-
The frequency component information "10" is expressed in a range of + a / 3 [V] to + a / 2 [V].

In FIG. 10, there are four types of information of modulation units (symbols), "00", "01", "11", and "10". Types of information change between adjacent modulation units are as follows.
There are the following 12 patterns. Pattern 01: Change from "00" to "01" (*) Pattern 02: Change from "00" to "11" Pattern 03: Change from "00" to "10" Pattern 04: From "01" to " Change to 00 "(*) Pattern 05: Change from" 01 "to" 11 "Pattern 06: Change from" 01 "to" 10 "Pattern 07: Change from" 11 "to" 00 "Pattern 08: Change from "11" to "01" Pattern 09: Change from "11" to "10" (*) Pattern 10: Change from "10" to "00" Pattern 11: From "10" to "01" Change pattern 12: Change from "10" to "11" (*) However, the mark * is a change pattern that does not cross the center level (0 [V]), and is a pattern that is not a target of periodicity judgment.

Here, focusing on the periodicity of the modulation unit for each pattern (excluding the mark *), the interval between two successive information change points is as follows for each pattern. Pattern 02 (“00” → “11”): Tc Pattern 03 (“00” → “10”): Ta pattern 05 (“01” → “11”): Ta pattern 06 (“01” → “10”) : Tb pattern 07 (“11” → “00”): Tb pattern 08 (“11” → “01”): Ta pattern 10 (“10” → “00”): Ta pattern 11 (“10” → “01”) "): Tc Among these, the interval between patterns 03, 05, 08 and 10 is the same as that of the binary FSK signal, but the interval between the other patterns 02, 06, 07 and 11 is different from Ta. Or Tc, that is, Tb or Ta shorter than Ta.
Since these Tc are longer, when these intervals are mixed, for example, when binary FSK and quaternary FSK are used together as in the above-mentioned advanced paging system, the difference between Ta and Tb and the difference between Ta and Tc Or the periodicity is impaired by the difference between Tb and Tc, and even if the first information change point (c) can be detected, the next information change point is three points 100
There is a problem that it is impossible to predict at all which of the values will be in the range of -102 (d-f).

It is also conceivable to set a wider prediction window including all the change points 100 to 102 and to evaluate the next information change point using this window.
On the other hand, a wider prediction window is not preferable because it makes it easier to detect unauthorized information change due to noise or the like, and causes deterioration in waveform detection accuracy.

Accordingly, the present invention makes it possible to detect a signal using the periodicity of a signal of a quaternary or higher multi-level multiplex modulation system, thereby reliably eliminating a received signal containing an error. And / or effective battery saving.

[0017]

According to a first aspect of the present invention, there is provided a waveform detecting method for detecting whether or not a waveform of a received multi-level multiplexed modulation signal is appropriate, using a prediction window for limiting a detection area. A first step of determining whether the logical value of the demodulated signal is apart from the reference level or not, and moving the position of the prediction window forward or backward based on the determination result of the first step. A third step of setting the shift amount and width of the prediction window based on the peculiarity of the demodulated waveform of the modulation signal; and a prediction having the shift amount and width set in the third step. Evaluating a logical change point of the demodulated signal using a window to determine whether or not the waveform of the modulated signal is appropriate. According to a second aspect of the present invention, in the first aspect of the present invention, in the fourth aspect, the evaluation of the logical change point of the received signal is performed on at least one of a rising edge and a falling edge of the received signal. It is characterized in that it is performed based on According to a third aspect of the present invention, there is provided the waveform detecting method according to the first aspect of the present invention, wherein the distance from the reference level is "10" or "00" of quaternary modulation. And According to a fourth aspect of the present invention, in the waveform detecting method for detecting whether or not the waveform of the received multi-level multiplexed modulation signal is appropriate using a prediction window for limiting a detection area, First determining means for determining whether the logical value is apart from the reference level or not, and first setting means for shifting the position of the prediction window forward or backward based on the determination result of the first determining means. A second setting unit that sets a shift amount and a width of the prediction window based on the peculiarity of the demodulated waveform of the modulation signal, and a prediction window having the shift amount and the width set by the second setting unit. A second step of evaluating a logical change point of the demodulated signal and determining whether or not the waveform of the modulated signal is appropriate;
Determining means. According to a fifth aspect of the present invention, in the waveform detecting apparatus according to the fourth aspect, the second setting means evaluates a logical change point of the received signal by at least one of a rising edge and a falling edge of the received signal. It is characterized by performing based on. According to a sixth aspect of the present invention, in the waveform detecting apparatus according to the fourth aspect, when the distance from the reference level is greater than
It is characterized in that it is the case of four-level modulation "10" or "00". According to a seventh aspect of the present invention, there is provided a waveform detecting method,
Whether or not the waveform of the received multi-level multiplexed modulation signal is appropriate is detected by using a prediction window that limits a detection area. In the waveform detection method, the logical value of the demodulated signal demodulated from the modulation signal is continuously changed. A first step of holding the two, a second step of setting the position of the prediction window based on the two logical values held in the first step, and a prediction window set in the second step. A third step of evaluating a logical change point of the demodulated signal to determine whether the waveform of the modulated signal is appropriate. In the waveform detecting method according to the invention described in claim 8, in the invention described in claim 7, in the third step, the evaluation of the logical change point of the received signal is performed at least one of a rising edge and a falling edge of the received signal. It is characterized in that it is performed based on 10. The waveform detection method according to claim 9, wherein in the waveform detection method for detecting whether the waveform of the received multi-level multiplexed modulation signal is appropriate or not using a prediction window for limiting a detection area. Holding means for continuously holding two logical values of the demodulated signal demodulated from,
Setting means for setting the position of the prediction window based on the two logical values held by the holding means, and evaluating the logic change point of the demodulated signal using the prediction window set by the setting means, and Determining means for determining whether the waveform is appropriate or not. Claim 10
In the waveform detecting device according to the invention described in the ninth aspect, in the invention according to the ninth aspect, the determination unit performs the evaluation of the logical change point of the received signal based on at least one of a rising edge and a falling edge of the received signal. It is characterized by.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to FIG.
An example of a pager of the LEX-TD standard will be described with reference to the drawings.

<Regarding the Configuration of the Pager> FIG. 1 is a block diagram of the pager. In the figure, 10 is an antenna, 20 is a receiver, 30 is an AD converter, and 40 is FLEX.
A decoder, 50 is an operation unit, 60 is a display unit, 70 is a notification unit, 80 is an instruction ROM unit, and 90 is a control unit. The functions of these units will be outlined below. (1) Antenna 10: 280 MH emitted from base station
This is a built-in main body antenna that receives radio waves in the z band (the carrier frequency fc of FLEX-TD). (2) Receiving section 20: a section for amplifying a signal received by the antenna 10 at a high frequency and performing a detection process and an FSK demodulation process.
In particular, in the FSK demodulation processing, binary FSK or quaternary FSK
8 are extracted, and a predetermined potential level (for example, ± a / 2 in FIG. 10) is applied to each extracted component.
[V] or a level corresponding to ± a / 6 [V].

(3) AD conversion unit 30: The signal from the reception unit 20 is converted into a binary FSK or quaternary FSK modulation unit (symbol).
This is a part for converting into 2-bit digital signals B ₀ and B ₁ every time. For example, three comparators 31 to 33, three reference voltages 34 to 36, and one decoder (a 3-bit input, 2-bit output decoder) 37 are provided. ~ 33
And the three reference voltages 34 to 36, FLEX-T
Digital signal B ₀ , B ₁ of 2 bits / symbol of D standard
In short, in the case of quaternary FSK, four ranges in the demodulated waveform of FIG. 10, that is, a range from -a / 2 [V] to -a / 3 [V],-
a / 3 [V] to 0 [V], 0 [V] to +
Range from a / 3 [V], + a / 3 [V] to + a / 2
The signal levels falling within the range up to [V] are converted to the corresponding FLEX-TD standard information (“00”, “01”,
"11", "10") and output. (4) FLEX decoder 40: provided with a data decoding unit 41 that converts the output of the AD conversion unit 30 into a signal format defined by the FLEX-TD standard, performs error correction processing and the like in 32-bit width block units, and outputs the result. In addition, a waveform detecting unit 42 and a battery saving unit 43, which are elements unique to the present embodiment, are provided.
Focusing on the periodicity of the modulation unit of the signal, it is for determining whether or not the received signal is appropriate for the advanced paging system.
Numeral 3 is for stopping the operation of unnecessary circuits (battery save-on) or restarting the operation (battery save-off) in response to the output of the waveform detection unit 42.

(5) Operation section 50: A section including various key switches. (6) Display section 60: A section that displays a message, date and time information, and the like, for example, includes a liquid crystal display. (7) Notification section 70: A section that generates a ringtone, notification vibration, and the like. (8) Instruction ROM section 80: A section for storing firmware and data necessary for the operation of the pager. (9) Control unit 90: based on a signal from the data decoding unit 41 or a signal from the operation unit 50, performs notifying control of a ring tone, display control of information (such as a message) included in the signal, and standby for incoming call. It is a part for performing date and time display control inside, for example, a part configured by a one-chip microcomputer.

<Regarding FLEX-TD> As described above, when a FLEX-TD standard receiver (here, a pager) demodulates a quaternary FSK signal, "00" and "0" are output.
Any one of information 1 "," 11 ", and" 10 "is obtained. In particular, in FLEX-TD, the first bit (x) and the second bit (y) of the information are referred to as a phase, and The bit strings of the phases are grouped in word units, error detection and correction are performed by BCH-code (Bose-Chaudhuri-Hocquenghem code) logic, and then the message information is reproduced. x ₁ , y ₁ ),
_{(X 2, y 2),} (x 3, y 3), (x 4, y 4), (x 5,
_{y 5), (x 6,} y 6), (x 7, y 7), when the ... data were obtained, in one of the phase corresponding to the first bit (x), "x _{1, x 2, x 3, x 4} , x 5, x 6, x 7,
.. ”, And in other phases corresponding to the second bit (y),“ y ₁ , y ₂ , y ₃ , y ₄ , y ₅ ,
, y ₆ , y ₇ ,... ”, and these bit strings are put together in words (32 bits), and error detection and correction are performed for each phase.

There are four types of phases in FLEX-TD: "A", "B", "C", and "D". 32
At 00 bps, two phases (first bit: phase A, second bit: phase C) are used, and 640
At 0 bps, all four phases (first bit: phase A
And phase C, second bit: phase B and phase D) (see Table 2).

[0024]

[Table 2]

FIG. 2 is a conceptual diagram of the data format of FLEX-TD. This format is 15 per hour
A cycle from CL0 to CL14 repeated a number of times;
FM0 repeated 128 times per cycle (4 minutes)
To FM127, one frame is composed of a field for a synchronization signal and BK0 to BK
It consists of up to 10 eleven blocks (also called interleaved blocks). The FLEX-TD standard receiver (here, pager) has an ID corresponding to one frame (written in the receiver at the stage of handing over to the user) and occupies 11 blocks of information included in the frame. (However, if it is not a variable reception cycle). The data amount of one block is 1600 bp of non-multiplexed data.
s is a reference and has a configuration of 8 words × 32 bits (see Table 3).

[0026]

[Table 3]

Where i is an information bit, p is a sign bit, and each word has 21 information bits, 10 check bits, and one parity bit, and has 1600 bps.
In non-multiplexing, one block is composed of eight words from 0A to 7A, so that one frame (11 blocks) has 88 words. The word 1
The first character indicates a word number, and the second character indicates a corresponding phase number. This number format is the same in two-channel multiplexing and four-channel multiplexing. Table 4 shows the block configuration in two-channel multiplexing, that is, 3200 bps in two phases.

[0028]

[Table 4]

In 3200 bps / 2 channel multiplexing, words of the same number are formed using two phases, phase A and phase C. For example, word 0 is phase A
And "0C" using phase C, which is twice as large as 1600 bps. As in the case of non-multiplexing, one frame (11 blocks) has 88 words. Table 5 shows the block configuration in four-channel multiplexing, that is, 6400 bps in four phases.

[0030]

[Table 5]

In 6400 bps / 4 channel multiplexing, words of the same number are formed using all (four) phases from phase A to phase D. For example, word 0 is four of “0A” using phase A, “0B” using phase B, “0C” using phase C, and “0D” using phase D, and is substantially 1600b.
Although the data amount is four times as large as ps, in this case as well, there is no change to the 8-word configuration when viewed from phase to phase.
As with non-multiplexing, 8 per frame (11 blocks)
Eight words. The transmission bit strings on the wireless channel are arranged in the column direction of Table 3, Table 4, or Table 5 in order from upper left to lower right. 3200bps and 6400bps
Block structure is code interleaving and multiple 1
A 600 bps data sequence is multiplexed and combined into one. Alternatively, it may be considered that a plurality of interleaved data are multiplexed together. For example, in the example of 6400 bps (Table 5), starting from word 0A, words 0B, 0C, 0
D, 1A,..., 7A, 7B, 7C, 7D,.

FIG. 3 is a conceptual diagram showing this situation (however, 1600 bps is omitted). In this figure, W0B
1 to W7B32 represent words and bits, for example, W0B1 represents bit 1 of word 0. According to this figure, at 3200 bps, two channels of phase A and phase C are multiplexed, and at 6400 bps, phases A to
Phase D 4-channel multiplexes can be read.
In the decoder built in the FLEX-TD standard receiver (the data decoding unit 41 of the FLEX decoder 40 in FIG. 1), for example, at 3200 bps, the phase A is converted from the bit string developed in the 8 × 32 array of the buffer memory. And data of phase C, or 6400 bp
If it is s, the data of phases A, B, C and D are extracted from the same bit string. This extraction processing is called multiplex separation, and at this stage, it is possible to determine the BCH (31, 21) code + even parity.

<Characteristic Operation of Waveform Detection Unit 42 (Part 1)> FIG. 4 is a flowchart showing the operation of the waveform detection unit 42 of the FLEX decoder 40 of FIG. It should be noted that the “flowchart” in this specification means whether the means of realization is hardware or software,
It simply refers to a diagram of the procedure of processing in the realizing means, and is not limited to a narrowly-defined flowchart in a so-called computer program. The processing in FIG. 4 is performed by a signal input to the waveform detection unit 42 of the FLEX decoder 40 in FIG. 1, that is, four information (“0”) of the FLEX-TD standard output from the AD conversion unit 30 in FIG.
0 "," 01 "," 11 "," 10 ")
This is executed in response to the state transition of the bit logic signals B ₀ and B ₁ . As shown in FIG. 1, this logic signal represents the above four pieces of information by a combination of B ₀ and B ₁ ,
“State transition” refers to the transition from one piece of information to another piece of information (eg,
4 means a change from “00” to “01”), that is, the rise or fall of the signal waveform.
Is a “rising” of the output signal of the AD converter 30.
Alternatively, it is executed in response to the “fall”.

When the processing in FIG. 4 is executed, first, the received signal, that is, the signal 2 output from the AD converter 30 in FIG.
The logical values (information) of the bit logical signals B ₀ and B ₁ are determined (S10), and the logical value is the maximum potential level (+ a / 2 in FIG. 10) of the four information of the FLEX-TD standard.
[V]) and the minimum potential level (-a / 2 in FIG. 10).
It is determined whether the information is two pieces of information (“10”, “00”) corresponding to [V]) (S11). And step S
In the case of a YES determination in step 11, the predetermined prediction window is shifted to the "back" (S12), and in the case of a NO determination, the window is shifted "forward" (S13). Here, the prediction window is a point in time when the execution of the processing in FIG.
The gate signal is, for example, a gate signal having a predetermined width La (see reference numeral 200 in FIG. 5) generated after a lapse of a certain time α from the “rise” or “fall” of the output signal of the D conversion unit 30. This is for evaluating whether or not the “rising” or “falling” of the next received signal (the output signal of the AD converter 30) occurs during the active period of the signal. And "shift" this window
Means that the time α is adjusted, and “shifting to the rear” includes two change points 101 and 102 at the center and right end of the three change points 100 to 102 in FIG. The thing (refer to FIG. 5A), “to shift forward” means that two of the three change points 100 and 102 in FIG. 10 are located at the left end and at the center. (See FIG. 5B).

In FIG. 10, the potential levels of the information "10" and the information "00" are the maximum and minimum potential levels, respectively, and the pattern which changes to another level starting from these levels is described above. From pattern 02
(“00” → “11”), pattern 03 (“00” → “1”
0 "), pattern 10 (" 10 "→" 00 ") and pattern 11 (" 10 "→" 01 "), except for change patterns that do not exceed the center level. Means that the signal always passes through the center change point 101 or the right end change point 102 as long as the signal is appropriate. Therefore, in the case of a YES determination ("10" or "00") in step S11, FIG. As shown in FIG. 5 (a), it is reasonable to shift the prediction window 200 to “back”.

On the other hand, in FIG. 10, the potential level of the information "11" or the information "01" is a potential level between the maximum and the minimum, respectively. According to the above description, pattern 05 (“01” → “11”) and pattern 06 (“01”
→ “10”), pattern 07 (“11” → “00”) or pattern 08 (“11” → “01”). However, change patterns that do not exceed the center level are excluded. The peculiar point of these change patterns is that the signal always passes through the change point 100 at the left end or the change point 101 at the center as long as the signal is appropriate. Therefore, in the case of a NO determination (not “10” or “00”) in step S11, it is reasonable to shift the prediction window 200 to “before” as shown in FIG. 5B.

After the window position is adjusted in step S12 or S13, it is next determined whether or not a change (rising / falling) of the received signal occurs at the adjusted window position (S14). In this case, it is determined that the received signal is appropriate, and a predetermined counter is incremented (S15). Then, it is determined whether or not the value of the counter becomes a sufficient value for the baud rate determination (S1).
7) Finally, if the value is sufficient, the battery saver is turned off (S18).
The battery save is set to “ON” (S19), and the process ends.

As described above, according to the present embodiment, when the logical value of the received signal is “10” or “00”,
In other cases, the position of the predetermined prediction window is shifted back and forth, and the shift amount and the width of the prediction window are set based on the specificity of the demodulated waveform (the waveform in FIG. 10) of the quaternary FSK signal. A prediction window whose position is actively changed according to the information of the quaternary FSK signal can be set as a prediction window. Can be determined correctly, and an extraordinary effect not found in the prior art can be obtained.

In the example of FIG. 4, after determining whether or not the baud rate is appropriate, that is, whether the signal of the multi-level multiplex modulation method is appropriate or inappropriate, the battery save is turned on / off in accordance with the result of the determination. (S18, S19)
However, this merely shows an example of a usage form of the determination result. For example, when the baud rate is not an appropriate value, the fact that the received signal contains an error may be displayed or used for error correction, or these may be used together with the battery save on / off. .

<Characteristic Operation of Waveform Detector 42 (Part 2)> FIG. 6 is a flowchart showing a modification of the above process (the process of FIG. 4). The code is attached. In FIG. 6, the difference from the above-described processing is that the position of the prediction window is set based on two consecutive logical values of the received signal. As a result, the width of the window can be narrowed, and the influence of noise and the like can be reduced to improve the accuracy of waveform detection. In FIG. 6, K and K _-1 are variables for storing logical values, and after the contents of K are moved to K _-1 (S3
1) The logical value of the received signal is stored in K (S3).
2). Then, the position of the window is set according to the combination of these two variables (K, K _-1 ) (S3
3), the setting conditions are schematized as shown in FIG.

In FIG. 7, for example, K- ₁ is "10".
And when K is “01”, the rightmost change point 102
Narrow window 3 at a position that contains only (see FIG. 10)
Set 00. The reason is “1” in FIG.
This is because the change pattern from “0” to “01” always passes through the rightmost change point 102 as long as the signal is appropriate.
When K ₋₁ is “10” and K is “00”, a narrow window 300 is set at a position including only the central change point 101 (see FIG. 10). The reason is that in FIG. 10, the change pattern from “10” to “00” always passes through the center change point 101 as long as the signal is appropriate. Alternatively, when K ₋₁ is “11” and K is “00”, a narrow window 300 is set at a position including only the leftmost change point 100 (see FIG. 10). The reason is,
In FIG. 10, the change pattern from “11” to “00” always passes through the change point 100 on the left end as long as the signal is appropriate. The same applies to other patterns.

Therefore, according to the processing example of FIG. 6, a narrow prediction window 300 corresponding to only one change point (see reference numerals 100 to 102 in FIG. 10) is used.
This is superior to the above-described processing (the processing in FIG. 4) in that it is less likely to be affected by noise or the like and can improve the accuracy of waveform detection.

<Regarding the Characteristic Operation of the Waveform Detection Unit 42 (Part 3)> In the above processing (the processing of FIGS. 4 and 6), in particular, the window position setting processing and the collation of the window with the received signal It is preferable that the processing (prediction evaluation processing) be synchronized with at least one of “rising” and “falling” of the received signal. This is because the change point of the received signal can be handled more periodically, and the worst case accompanying the change in the threshold value (the potential level of the reference voltages 34 to 36 in FIG. 1) can be avoided. That is, FIG.
, The center level (0 [V] in the figure) is one of the thresholds, and this level is, for example, -a / 6
Considering that the level has changed to the same level as [V], the maximum change point distance corresponding to the level after the change is the interval between two black circles (d ', he'), and this interval is the interval before the change. Since it is wider than the maximum change point distance (interval between the change point 100 and the change point 102) that matches the level (center level), when both “rising” and “falling” are used, two black circles (d) ′ And ′ ′) are both detected, which hinders the window position setting process. However, if only one of “rising” and “falling” is used, only one of the two black circles (d ′, ′) is used. This is because such a worst case can be avoided without detection.

[0044]

According to the first or fourth aspect of the present invention, the position of the predetermined prediction window is shifted forward and backward depending on whether the logical value of the demodulated signal is apart from the reference level or not. Since the shift amount and the width of the prediction window are set based on the peculiarity of the demodulated waveform of the modulation signal, a prediction window whose position is actively changed according to the information of the modulation signal can be obtained. Of course, the appropriateness of the modulation signal
It is possible to obtain an extraordinary effect that the inappropriateness can be correctly determined, which is not available in the related art. According to the seventh or ninth aspect of the present invention, the position of the prediction window is set based on two consecutive logical values of the demodulated signal, so that the width of the prediction window can be reduced, and noise and the like can be reduced. It is possible to reduce the influence and improve the accuracy of waveform detection. According to the second, fifth, eighth, or tenth aspect of the present invention, the evaluation of the logical change point of the received signal is performed based on one of the rising edge and the falling edge of the received signal.
The change point of the received signal can be handled more periodically, and the worst case caused by the threshold value change can be avoided. According to the third or sixth aspect of the present invention, when the distance from the reference level is far from the reference level, "10" or "0"
Since it is set to 0 ", for example, the present invention can be applied to a mixed environment of binary FSK and quaternary FSK of FLEX-TD.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment.

FIG. 2 is a frame configuration diagram of FLEX-TD.

FIG. 3 is a conceptual diagram of a phase.

FIG. 4 is a flowchart of the first embodiment.

FIG. 5 is a conceptual diagram of a window according to the first embodiment.

FIG. 6 is a flowchart of an embodiment (part 2).

FIG. 7 is a conceptual view of a window according to the second embodiment.

FIG. 8 is a frequency spectrum diagram of a quaternary FSK signal.

FIG. 9 is a demodulated waveform diagram of a binary FSK signal.

FIG. 10 is a demodulated waveform diagram of a quaternary FSK signal.

[Explanation of symbols]

200 prediction window 300 prediction window S10 step (first step, first determination means) S12 step (second step, third step, first step)
Setting means, second setting means) S13 step (second step, third step, first step)
Setting means, second setting means) S14 step (fourth step, second determining means, determining means) S31 step (first step, holding means) S32 step (first step, holding means) S33 step (second step, Setting means)

Claims (10)

[Claims] 1. A waveform detecting method for detecting whether or not the waveform of a received multi-level multiplexed modulation signal is appropriate using a prediction window for limiting a detection area, wherein a logical value of a demodulated signal departs from a reference level. And if
A first step of judging otherwise, a second step of shifting the position of the prediction window back and forth based on a result of the determination of the first step, a demodulation of the modulation signal by shifting a shift amount and a width of the prediction window. A third step of setting based on the peculiarity of the waveform, and a logical change point of the demodulated signal is evaluated using a prediction window having a shift amount and a width set in the third step, and the waveform of the modulated signal is appropriate. A fourth step of determining whether or not a waveform is detected. 2. The waveform detecting method according to claim 1, wherein said fourth step evaluates a logical change point of said received signal based on at least one of a rising edge and a falling edge of said received signal. . 3. When the distance from the reference level is different,
2. The waveform detection method according to claim 1, wherein the case is four-level modulation "10" or "00". 4. A waveform detecting method for detecting whether a waveform of a received multi-level multiplexed modulation signal is appropriate or not by using a prediction window for limiting a detection area, wherein a logical value of a demodulated signal departs from a reference level. And if
A first determination unit that determines that the case is not the case, a first setting unit that shifts the position of the prediction window forward or backward based on a determination result of the first determination unit, and a modulation amount and a width of the prediction window that are shifted. Estimating a logical change point of the demodulated signal by using a second setting means for setting based on the peculiarity of the demodulated waveform of the signal and a prediction window having a shift amount and a width set by the second setting means; A second determining means for determining whether the signal waveform is appropriate or not, a waveform detecting device comprising: 5. The waveform detection device according to claim 4, wherein said second setting means evaluates a logical change point of said received signal based on at least one of a rising edge and a falling edge of said received signal. apparatus. 6. When the distance is different from the reference level,
5. The waveform detection device according to claim 4, wherein the case is "10" or "00" of quaternary modulation. 7. A waveform detection method for detecting whether a waveform of a received multi-level multiplexed modulated signal is appropriate or not by using a prediction window for limiting a detection area, wherein a logic of a demodulated signal demodulated from the modulated signal is provided. A first step of continuously holding two values, a second step of setting the position of the prediction window based on the two logical values held in the first step, and a second step of setting the position of the prediction window. A third step of evaluating a logical change point of the demodulated signal using a prediction window to determine whether or not the waveform of the modulated signal is appropriate. 8. The waveform detecting method according to claim 7, wherein said third step evaluates a logical change point of said received signal based on at least one of a rising edge and a falling edge of said received signal. . 9. A waveform detection method for detecting whether a waveform of a received multi-level multiplexed modulated signal is appropriate or not using a prediction window for limiting a detection area, wherein a logic of the demodulated signal demodulated from the modulated signal is provided. Holding means for holding two values in succession; setting means for setting the position of the prediction window based on the two logical values held by the holding means; and a prediction window set by the setting means. Determining means for evaluating a logical change point of the demodulated signal to determine whether or not the waveform of the modulated signal is appropriate. 10. The waveform detection device according to claim 9, wherein said determination means evaluates a logical change point of said received signal based on at least one of a rising edge and a falling edge of said received signal.