JPH09231334A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver capable of quickly judging the reliability of received data. SOLUTION: The receiver for judging the start of communication the existence of an error, the generation of abort/stop, and whether another pseudo random signal is received or not at the time of receiving a pseudo random signal and executing communication is provided with arithmetic means 14, 15, 115 for calculating the self-correlation values R, N of the pseudo random signal, a detection means 112 for detecting the receiving level A of the pseudo random signal and means 113, 114 for executing judgement based upon the self-correlation values R, N and the receiving level A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving device, and more particularly, to a data reading device for reading data transmitted from a coin-shaped or card-shaped data storage body by contact in a pseudo-random coding system without contact. For receiving devices such as. Note that a data storage body that receives a command or the like also corresponds to the receiving device if the communication is based on the pseudo-random encoding method.

[0002]

2. Description of the Related Art Conventionally, as a data reading method capable of reading data from a data storage body without contact, a method utilizing communication by electromagnetic coupling is known. As the communication system, a digital modulation system such as a differential phase shift keying system communication is generally used. However, in the digital modulation system communication, sufficient reliability can be ensured when used in a noisy environment. Since it is difficult, there is known a system in which the reliability is improved by using a pseudo random signal.

FIG. 5 shows a block diagram of a system for executing a data reading method by communication of an encoding method using such a pseudo random signal. In short, in this system, a reader 10 as a data reading device uses a data reading method. The storage data is read from the storage body 20 by communication of a combination of a digital modulation system and a pseudo random coding system. That is, in the system of the pseudo-random coding system, the command (command) is generally transmitted from the reader 10 to the data storage body 20 with less restrictions, while the communication of the digital modulation system is relatively simple. Data return from the data storage body 20 that is subject to many noises and is susceptible to noise to the reader 10 is performed by a pseudo-random coding method using, for example, a 7-bit M series M ₀ , M ₁ as a pseudo-random signal. The configuration for that will be described below.

The reader 10 uses a microcomputer 11 for performing processing such as command transmission and data reception, and a carrier of a predetermined transmission frequency (ω ', for example, 1 MHz) according to a command from the microcomputer 11 in a predetermined system. A modulation circuit 12 that performs modulation and generates a transmission signal, and a transmission unit 13 that has a transmission coil and a reception coil and electromagnetically converts the transmission signal from the modulation circuit 12 by the transmission coil and transmits it to the outside.
And a demodulation section including an M ₀ correlation calculation circuit 14 and an M ₁ correlation calculation circuit 15.

The M ₀ correlation calculating circuit 14 receives the signal received by the receiving coil of the transmitting unit 13, and a predetermined receiving frequency band (center frequency ω, for example, ω = ω '/ of the received signal is received.
4 = 250 kHz) to separate the received signal from the data storage body 20, multiply the separated received signal by the local oscillation signal cos (ωt), and then correlate with the M sequence M _0. While calculating one orthogonal component M ₀ x of the autocorrelation value, the local oscillation signal sin (ωt) is calculated from the received signal.
And the other orthogonal component M ₀ y of the autocorrelation value is calculated based on M and M sequence M ₀ (see FIG. 6). Similarly, the M ₁ correlation calculation circuit 15 converts the received signal from the local oscillation signal co
The orthogonal components M ₁ x and M ₁ y of the autocorrelation value are calculated based on s (ωt), sin (ωt) and the M sequence M ₁ . The first half of both circuits 15 and 16 are common and therefore have a shared structure.

Microcomputer 11 of reader 10
Determines that a communicable data memory has been detected when a maximum autocorrelation value R described later exceeds a predetermined first threshold value S1, and causes the command transmission program 11b and the data acceptance program 11d to start data reading. In order to detect a data storage body that can communicate with the start determination program 11a, which performs a predetermined notification process, a read command such as a test command is constantly issued. After receiving the data read start notification, a command sending program 11b for performing a process of issuing a desired read command to the modulation circuit 12 by sequentially or appropriately updating the read target address is installed, and the command is digitally sent. The data is modulated and transmitted to the data storage body 20.

Further, the microcomputer 11 of the reader 10 calculates the autocorrelation value M ₀ from the orthogonal components M ₀ x and M ₀ y of the autocorrelation value, and the orthogonal component M ₁ x, of the autocorrelation value.
An autocorrelation value processing program 11 for calculating an autocorrelation value M ₁ from M ₁ y, comparing the autocorrelation values M ₀ and M _{1 and} setting the larger one as the maximum autocorrelation value R 11.
c and which of the M series M ₀ and M ₁ has been received according to the comparison result D in the processing of the autocorrelation value processing program 11c, that is, which of the data “0” and “1” has been sent. And a data receiving program 35 that receives data by determining
The data transmitted from the pseudo-random code is received.

Further, the microcomputer 11 of the reader 10 determines that the reliability of the received data is too low when the maximum autocorrelation value R is below a predetermined second threshold value S2, and performs error processing on the data receiving program 11d or the like. A stop determination program 11e that performs a process of giving a predetermined notification to perform the stop process is also installed, and malfunctions due to noise or the like are reduced.

The data storage unit 20 has a microcomputer 21 for processing such as command reception and data transmission, a memory 22 for holding stored data, a coil for both transmission and reception, etc., and electromagnetic signals from the reader 10 are electromagnetically generated. A transmission unit 23 for converting and receiving, and a reception signal from the transmission unit 23 are received to separate a desired reception signal by passing only a predetermined reception frequency band (ω ′), and a demodulation signal is generated from the reception signal. The demodulation circuit 24 for generating is provided to receive a command which is digitally modulated and sent from the reader 10.

The microcomputer 21 of the data storage unit 20 accepts the read command from the reader 10 based on the demodulated signal from the demodulation circuit 24, extracts the read target address contained in the read command, and reads the data read program 2
Command acceptance program 21a for performing processing of notifying 1b
When receiving the notification from the command receiving program 21a, the memory 22 is accessed to read the stored data in the read target address area and the data sending program 2
Data read program 21b for performing processing of notifying 1c
And a data sending program 21c for receiving the notification from the data reading program 21b and sending the above-mentioned data from the memory 22 to the selection circuit 25, which will be described later, are installed, and the return data is prepared in response to the read command. It has become a thing.

Further, the data storage unit 20 corresponds to the value ("0" / "1") of the data transmitted by the processing of the data transmission program 21c, and the M ₀ generation circuit 26 and the M ₀ generation circuit 26.
_The selection circuit 25 that selects _{one of the 1} generation circuits 27 and sends a trigger, the M ₀ generation circuit 26 that generates an M sequence M ₀ when the trigger is received, and the M sequence M when the trigger is received.
M ₁ generating circuit 27 for generating ₁ is provided, and the returned data is pseudo-randomly encoded and transmitted to the reader 10.

The reader 10 and the data storage 2 as described above
At 0, the following data request and data return transmission / reception are performed for reading stored data.

First, a read command or a simple test command is sent from the reader 10 to the data storage unit 20 via the modulation circuit 12 and the transmission unit 13 by the processing of the command sending program 11b. This transmission is repeated until the data storage body 20 enters the communicable range. That is, the process is repeated until the maximum autocorrelation value R exceeds the threshold value S1. In a noisy situation, it may be carefully repeated until it exceeds a predetermined number of times, for example, three times.

When the data storage body 20 enters the communicable range in this manner, the read command is accepted by the command acceptance program 21a in the data storage body 20 via the transmission section 23 and the demodulation circuit 24, and in response thereto. Memory 22
The corresponding storage data of is read for return. Alternatively, predetermined fixed data corresponding to the test command, for example, M series M ₀ is prepared. Then, the corresponding data is transmitted from the data storage body 20 to the reader 10 via the data transmission program 21c, the selection circuit 25, and the like.

The stored data returned as data is
Further, in the reader 10, the transmission unit 13 and the correlation calculation circuit 1
It is accepted by the data acceptance program 11d via 4,15. Then, by repeating the processing of such a procedure for the corresponding address as appropriate, the data storage unit 2
The desired storage data of the memory 22 at 0 is the reader 10
Read by.

In this way, the stored data is read by the communication of the pseudo random coding system. Further, in this processing, the start determination program 1 in the reader 10
Based on the maximum autocorrelation value R, the determination of the start or stop condition by the 1a or the stop determination program 11e is appropriately performed.

[0017]

In such a conventional data reading apparatus, in order to obtain a communication capability beyond the communication of a simple digital modulation system, and also as a noise countermeasure, a pseudo random coding system communication is used. The data is returned by and the reliability of the received data is determined based on the maximum autocorrelation value. That is, the start determination of data reading, the error determination, and the stop / stop determination are performed based on the maximum autocorrelation value.

However, the autocorrelation value is supposed to increase only when the received signal coincides with the M sequence or the like expected by itself, but when the noise level is very high, the received signal is expected by itself. Even when there is a disagreement with the M-sequence etc., it may be considerably large. When the received signal level is low, the value may increase as the received signal exceeds the value when it coincides with the M sequence or the like. For example, in a situation where the correlation value due to noise reaches 1/3 of the maximum autocorrelation value at the time of reception at the maximum level, the value is in a situation where the reception level is only 1/3 even if there is no noise. It will be equivalent to the proper maximum autocorrelation value. Therefore, even in the reliability determination of the received data based on the maximum autocorrelation value, if the noise level is very high, there is a risk of erroneous determination.

Further, repeating the reliability determination a plurality of times as described above is unsatisfactory in that the processing speed is sacrificed.
Moreover, although it contributes to the improvement of reliability to some extent, it is still ineffective for continuous noise over the repetition period. So, the situation where large noise continues,
For example, an issue is to avoid erroneous determination even in a situation where a broadcasting station is nearby, and to avoid erroneous determination without repeating reliability determination a plurality of times.

The present invention has been made in order to solve such a problem, and an object thereof is to realize a receiving apparatus for promptly determining the reliability of received data.

[0021]

The constitutions and effects of the first and second solving means invented to solve the above problems will be described below. [First Solving Means] The receiving device of the first solving means (as described in claim 1 at the beginning of the application) receives a pseudo-random signal and performs communication for data reading, etc. Is a receiving device such as a data reading device for determining whether or not is a pseudo random signal, and calculating means for calculating an autocorrelation value of the pseudo random signal, and detecting a receiving level of the pseudo random signal. And a detection means,
It is characterized in that the determination is performed based on the autocorrelation value and the reception level according to whether or not a ratio of these exceeds a predetermined threshold value.

Here, the M-sequence is generally used as the pseudo-random signal, but a Hall sequence or the like may be used. Further, as the autocorrelation value, there is a so-called non-correlation value when the correlation cannot be obtained, in addition to the peak value when the correlation is good. And not only these but also the case where only one is used is also included.

In the receiving device of the first solving means as described above, the pseudo random signal is used in order to enhance the reliability of the received data at the time of communication. Then, it is determined whether or not the pseudo-random signal is received, in other words, it is determined whether or not the reliability of the received data can be secured. Moreover, this determination is performed not only based on the maximum autocorrelation value but also on the reception level in addition to the autocorrelation value. Here, the autocorrelation value and the reception level have a characteristic that an ideal or appropriate maximum autocorrelation value is almost uniquely determined corresponding to each value of the reception level.

Therefore, even when the noise is strong and the autocorrelation value becomes undesirably large, the autocorrelation value is compared with the ideal maximum autocorrelation value expected corresponding to the received signal level at that time. By doing so, it is possible to reliably determine whether or not the received signal matches the M sequence or the like expected by itself. Moreover, it is possible to make the determination promptly with a single process.

Therefore, according to the present invention, it is possible to realize a receiving device for quickly determining the reliability of received data.

[Second Solving Means] The receiving device of the second solving means (as described in claim 2 at the time of filing the application) is the receiving device of the first solving means, and as the determination or In addition to or instead of the above, a means for performing at least one of a communication start determination, an error determination, and a stop / stop determination is provided.

In the receiving device of the second solving means as described above, the reliability judgment of the received data for starting communication is based not only on the maximum autocorrelation value but also on the reception level in addition to the autocorrelation value. Is done. Therefore, as described above, the communication start determination, the error determination, and the stop / stop determination can be reliably performed. Moreover, it is possible to make the determination promptly with a single process. Therefore, according to the present invention, it is possible to realize a receiving device that quickly determines the reliability of received data.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment for carrying out the present invention is the receiving device of the above-mentioned first and second solving means, wherein the maximum of the reception level and the autocorrelation value is set. The determination is performed based on the autocorrelation value and / or the minimum autocorrelation value. Specifically, regarding the ratio between the maximum autocorrelation value and the reception level, a value in an ideal state where there is no noise is set to 100%, and an intermediate value, for example, a value of 50% thereof is set to the first threshold value S0 and stable. The data storage is arranged at a position where it can be read out, and the correlation calculation is performed on the received signal. The maximum autocorrelation value obtained at this time is set as the second threshold value TS, and the autocorrelation value due to noise at the allowable limit level is set as the third threshold value. As TN (At this time, T
S> TN), and is determined according to any of the following items.

Using the above S0 and TS, when the ratio of the maximum autocorrelation value to the reception level exceeds S0 and the maximum autocorrelation value is larger than TS, it is determined that the received data is reliable ( That is, it is determined that the received signal is a pseudo random signal, that communication can be started, that there is no error, that the current communication should be stopped or stopped, and that the data is invalid). As a result, it is possible to make a sharp distinction as to whether the desired M sequence has been received and the correlation value has increased, or whether the correlation value has increased due to noise. This is because the maximum correlation value increases due to noise, but the reception level hardly changes. As a result, the accuracy of the determination is improved, and it is possible to accurately determine whether or not the data storage unit is within the accessible range by a single command transmission / data return.

When the above-described S0 and TS are used, the ratio of the maximum autocorrelation value to the reception level exceeds S0, the maximum autocorrelation value is larger than TS, and the minimum autocorrelation value is smaller than TN. First, it is determined that the received data is reliable. When the correlation value becomes large due to noise, there is a characteristic that not only the maximum autocorrelation value but also the minimum autocorrelation value also becomes large. The reliability of the determination can be further enhanced.

Using the above-mentioned S0, TS and TN, the ratio between the maximum autocorrelation value and the reception level exceeds S0,
And the ratio of the maximum autocorrelation value to the minimum autocorrelation value is TS / T
When it is larger than N, it is determined that the received data is reliable. This also makes it possible to make a determination in consideration of the minimum autocorrelation value.

In the above or, in T
At least one of S, TN, TS / TN, S0
One is not a fixed value, but a linear equation or 2
It is calculated before the determination according to the following formula or the formula of polygonal line approximation. Since the reception level changes non-linearly according to the communication state such as the distance with the communication partner such as the data storage body, the relationship between the reception level and each threshold may not be fixed depending on the communication state. . Therefore, by performing a flexible determination according to the reception level, for example, when a normal data return is received at a small reception level from a data storage body at a distant position, it is erroneously determined that the data storage body does not exist. Such undesiredness is reduced.

[0033]

【Example】

[First Embodiment] A specific configuration of the first embodiment of the receiving apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a system that executes a data reading method by communication in a pseudo-random encoding system, and corresponds to FIG. 5 of a conventional example. This system is different from the conventional one only in the portion related to the reliability judgment of the received data in the reader 100 as the receiving device, and therefore, the same components are designated by the same reference numerals and their re-explanation will be omitted. Omit. Hereinafter, the differences will be mainly described.

The reader 100 uses not only the maximum autocorrelation value R but also the minimum autocorrelation value N and the received signal level A to judge the reliability of the received data. Level detection program 1
12 is added, and a start determination program 113 and a stop determination program 114 as means for making one determination.
Has been improved, and the autocorrelation value processing program 115 as an arithmetic means has also been improved.

When the autocorrelation value processing program 115 calculates the autocorrelation values M ₀ and M ₁ of the pseudo-random signal and sets the larger one to the maximum autocorrelation value R, the remaining smaller one is used. The processing for setting the minimum autocorrelation value N is also performed.

The level detection program 112 receives the output of the A / D conversion circuit in the M ₀ correlation calculation circuit 14 (see FIG. 6) and obtains the received signal level A corresponding to the amplitude (for specific processing procedure). Will be described later). In FIG. 1, for convenience, M _0X and the like are shown as being input, but in detail, it is the output of the A / D conversion circuit.

In determining the detection of the communicable data storage, the start determination program 113 does not immediately make the determination of the detection only because the maximum autocorrelation value R exceeds the threshold value S1. The determination of detection is made only when the minimum autocorrelation value N is smaller than other small threshold values and the ratio between the maximum autocorrelation value R and the reception level A exceeds a predetermined threshold value S0. In addition, it is possible to make a determination to that effect by one detection.

This threshold value S0 is obtained by sampling the received pseudo-random signals at 100 points and correlating them with the M series consisting of ± 1 columns, and inversion due to noise is 2
Assuming that 0% is allowed, (100 x A) x (1-
0.2) / A, that is, 80. When the allowable limit level of noise is other than this, the value of 0.2 is replaced with the corresponding value and similarly determined. Also, in the case of 7-point sampling, replace 100 at 7 with 5.6.
It is said. As a result, it is possible to promptly determine the start of data reading with higher reliability than before.

Similarly, the stop determination program 114 also uses the minimum autocorrelation value N and the received signal level A in addition to the maximum autocorrelation value R to determine the reliability of received data for error processing and stop processing. It is like this.

The operation of the system of this embodiment at the time of reading data will be described. FIG. 2 is a communication diagram between the reader 100 and the data storage body 20. Note that the example of FIG. 2 shows a case where the data storage body 20 approaches and leaves the reader 100 at an extremely high speed in order to explain even the case of error processing. The distance is fixed or changes gently depending on the communication speed.

When the reader 100 is started by turning on the power, etc., the reader 100 transmits an M ₀ request command as a pseudo random signal request command by the processing of the command sending program 11b. However, if the data storage body 20 is too far away, this M ₀ request command does not reach the data storage body 20. At this time, the maximum autocorrelation value R is less than or equal to the threshold value S1. Therefore, the reader 100 continues to issue the M ₀ request command.

On the other hand, the data storage body 20 is the reader 1
00, the M ₀ request command from the reader 100 reaches the data storage body 20. Then, the processing and M ₀ generating circuit 26 and the like of the command receiving program 21a, M-sequence M ₀ (for example, 7-bit data sequence "1
011100 ″) is from the data storage unit 20 to the reader 100.
Will be returned to In this way, according to this data reading method, the M series M ₀ , which is a pseudo-random signal, is transmitted from the data storage body 20 to the reader 100 prior to the original reading of the stored data.

When the transmission level of the data storage body 20 is C, the reception level of the reader 100 is C ', and the phase difference due to transmission is φ, the return of the M sequence M ₀ is the data storage body. 20 at C × M ₀ (t) × cos (ω
If it is t), C ′ × M ₀ (t) × cos (ωt + φ) is reached when it reaches the reader 100 (provided that C> C ′). Here, M ₀ (t) is 1 (corresponding to the sequence “1”) or (the sequence “0” according to the M sequence M ₀ (for example, “1011100”) at a timing of ω / 4 = 62.5 kHz, for example. "Corresponding to").

The reader 100, which has received C ′ × M ₀ (t) × cos (ωt + φ), receives the correlation calculation circuits 14 and 1 shown in FIG.
Input a signal to 5, and first use LPF (for example, pass only 500 kHz or less) to generate a carrier wave of 1 MHz from reader 100.
Get rid of. As a result, only the return signal from the data storage body 20 can be taken out. Next, this received signal is multiplied by the local oscillation signal cos (ωt) by the multiplier.
As a result, C ′ × M ₀ (t) × (cos (φ) × cos
(2ωt) −sin (φ) × sin (2ωt)) / 2+
C ′ × M ₀ (t) × cos (φ) / 2 is obtained. When this is passed through an LPF, C ″ × M ₀ (t) × cos (φ)
(Where C ″ = (C ′ / 2)). Similarly, C ″ × M ₀ (t) × sin (φ) is extracted from the side multiplied by the local oscillation signal sin (ωt).

Correlation calculation uses A /
D conversion is performed and this digital data is multiplied by M ₀ (t) (however, M ₀ (t) is 1 or −1.
Since it only takes the value of, it can be realized by switching between addition and subtraction). That is, M _0X = ΣM ₀ (t) × C ″ ×
M ₀ (t) × cos (φ), M _0Y = ΣM ₀ (t) × C ″
× M ₀ (t) × sin (φ).

Now, assuming that C = 128, attenuated to 3/4 due to transmission, C '= 96, φ = π / 6, and the conversion timing of A / D conversion is ω / 2 = 125 kHz, C ″ = 4.
Since it is 8, M _0X = 48 × cos (π / 6) × ΣM ₀
(T) × M ₀ (t), and ΣM ₀ (t) × M ₀ (t)
Is (sequence length) x (number of samples per chip) =
Since 7 × 2 = 14, M _0X = 582. Similarly, M _0Y = 48 × sin (π / 6) × 14 = 336.

Next, in the M ₁ correlation calculation circuit 15,
Since the specific sequence value used when calculating the correlation is only different from that of the M ₀ correlation calculation circuit 14, M
_1X = ΣM ₁ (t) × C ″ × M ₀ (t) × cos (φ),
M _1Y = ΣM ₁ (t) × C ″ × M ₀ (t) × sin (φ)
Becomes Here, if the M sequence M ₁ is “1100101”, ΣM ₁ (t) × M ₀ (t) = 1 × 1 + 1 × 1
+ (-1) x1 + (-1) x1 + 1x (-1) + 1x
(-1) + 1x (-1) + 1x (-1) + 1x1 + 1x
1 + (-1) x (-1) + (-1) x (-1) + (-
1) × 1 + (− 1) × 1 = −2, so M _1X = −8
3, M _1Y = −48. Further, by the autocorrelation value processing program 115, M ₀ = (M _0X ² + M _0Y ² ) ^1/2
= 672, M ₁ = 96, and the maximum autocorrelation value R = 67
2. The minimum autocorrelation value N = 96 is captured. Note that M ₀ = | M _0X | + | M _0Y | may be set in the calculation process (see the second embodiment).

On the other hand, the received signal level A is obtained by the level detection program 112 from the same A / D converted data as follows. A = Σ ((C ″ × M ₀ (t) × cos (φ)) ² +
(C ″ × M ₀ (t) × sin (φ))) ² ) ^1/2 / (number of samplings) = C ″. Therefore, A = 48
And the ratio between the maximum autocorrelation value R and the received signal level A is 672/48 = 14. In addition, as in the above-mentioned example, in the case of 1 sampling for 1 chip, R = 3
36, N = 48, A = 48, R / A = 7 are obtained.

Then, the maximum autocorrelation value R is set to the threshold value S1 (for example, 4 by the processing of the start determination program 113).
00) is detected, and the minimum autocorrelation value N
Is detected below another small threshold (eg, 200), and it is also detected that the ratio R / A is greater than 5.6 described above.

In this way, since it is found that both the reader 100 and the data storage body 20 are in the communicable state, the start determination program 113 sends the command sending program 11b.
The data reception program 11d is notified of the start of data reading. After that, the reader 1 in the conventional example
0 and the data storage unit 20, the read target address is, for example, A1, A
2, A3 ... While being updated, the data request by the reader 100 and the data return by the data storage body 20 are transmitted and received.

For example, when C ″ = 40 and φ = π / 4, the data after A / D conversion is {+2 on both the X and Y sides.
8, -28, +28, +28, +28, -28, -2
8}, and the maximum autocorrelation value R = 28 at this time
It should be × 7 = 277, the minimum autocorrelation value N = 40, and the received signal level A = 40. However, because strong noise was added to the fifth sampling data, for example, {+2
8, -28, +28, +28, -28, -28, -2
8}, M _0X = M _0Y = 140, M _1X = M _1Y =
The maximum autocorrelation value R = 198 and the minimum autocorrelation value N = 119 are obtained. The received signal level A is 40. The maximum autocorrelation value R and the received signal level A are 198/40 = 4.95.

Then, the stop determination program 114 detects that the ratio R / A is smaller than 5.6 described above, and it is determined that the received data is unreliable due to strong noise, so an error determination is made. . Then, from the stop determination program 114 to the command transmission program 11b
A data read retry notification is sent to the data reception program 11d. Further, if the reception is not properly received even after a predetermined number of attempts, a stop determination is made and the stop determination program 1
14 sends a notification to that effect to the command sending program 11b and the data receiving program 11d.

In this way, the reader 100 makes all of the start judgment, the error judgment, and the stop judgment based on not only the maximum autocorrelation value R but also the received signal level A, etc., so that even in a noisy environment. It is possible to reliably avoid erroneous determination. After that, the reader 100 returns to the transmission state of the M ₀ request command in order to detect the next communication partner.

[Second Embodiment] A reader (data reading device) as a second embodiment of the receiving apparatus of the present invention will be described. FIG. 3 is a block diagram thereof, and FIG. 4 is an example of sampling a received signal. Differences from the above-described device will be described.

This reader 100 replaces the above level detection program 112 with the next level detection program 11
2a is provided. This is because the autocorrelation value processing program 115 has the maximum autocorrelation value R and the minimum autocorrelation value N.
Corresponding to the calculation by the simple calculation, the received signal level A is calculated by the similar simple calculation. It also determines whether or not the read data from the data storage body 20 is valid.

More specifically, the level detection program 112
a performs the same processing as the autocorrelation value processing program 115 or uses the calculation result thereof, so that from the outputs of the A / D conversion circuits in the M ₀ correlation calculation circuits 14 and 15,
The received signal level A is obtained. That is, the M ₀ x side A / D conversion output value is set to Mx _i, and the M ₀ y side A / D conversion output value is My _i.
As one set of orthogonal components Mx _i, the sum from the My _i a _i = | Mx _i
Calculate | + | My _i |. Moreover, it is performed multiple times for each reception according to the sampling number. For example, if the M sequence is 15 bits and each bit is sampled twice,
Sums a _{1 to} a ₃₀ are calculated corresponding to a total of 30 samplings (see FIG. 4). Then, the predetermined reference level is set to 127, which is half the maximum value 255, and the expression [A = {Σ | a
_i- 127 | / 30}] is used to calculate the received signal level A.

Further, the level detection program 112a is
Upon receiving the comparison result D of the autocorrelation value processing program 115, it is determined whether or not the read data from the data storage body 20 is valid, and when it is determined that the read data is valid, the comparison result D is directly used as the data. On the other hand, when it is determined that the read data is invalid, the read data is error-corrected and the corrected result is delivered to the data receiving program 11d.

Further, the correctness determination and error correction processing of the read data is performed by adding a predetermined plurality of bits of redundant data to the storage data carrying the original information. That is, the data storage body returns redundant data to the reader, and the reader that receives this multiplies the received data by a predetermined inspection matrix or correction matrix corresponding to the predetermined redundant data, and the operation result If it is correctable, it is corrected, and if it is an uncorrectable error, it is determined to be invalid.

However, when the data is read using the pseudo-random sequence code, it is possible to correct an error that is higher than the original correction capability, or to prevent erroneous correction. For example, a case where a 2-bit error occurs in the 1-bit error correction code will be described.
Correct data is set to D = (110011), and the inspection matrix is

[Equation 1] And

In this case, if transposition is indicated by ^T , H × D ^T becomes (000) ^T , but assuming that the received data becomes D ′ = (111011) because the third bit is incorrect, H × D ^T becomes H Since × D ′ ^T = (001) ^T , which coincides with the third column of the check matrix, it can be understood that the third bit is wrong, and it can be corrected as D ′ + (001000) = D.

However, when D '= (110101) and the fourth and fifth bits are erroneous, H × D' ^T =
Since it becomes (101) ^T , which coincides with the sixth column of the check matrix, the sixth bit is erroneously determined.

However, the maximum autocorrelation value R tends to be small where there are errors, although it is large for bits where there are no errors. Moreover, in general, the error correction code is
If the position of the error bit can be specified, the error correction capability is improved as compared with the case where the position of the error bit cannot be specified, that is, which bit is wrong.

Therefore, on the basis of these characteristics, it is better to give priority to the place where the maximum autocorrelation value R is small or the place where the ratio between the maximum autocorrelation value R and the received signal level A is small, and to judge as the error occurrence place. I understand. For example, the maximum autocorrelation value R for each bit is 100, 100, 100,
If it is 20, 20, and 100, it is better to judge that the 4th and 5th bits are wrong than to judge that the 6th bit is wrong. By doing so, even if it is originally possible to correct only a 1-bit error and the operation cannot be guaranteed for an error of 2 bits or more, erroneous correction can be prevented or a 2-bit error can be corrected. Become.

Thus, when performing the error correction, if the maximum autocorrelation value R of each read bit is not less than or equal to the predetermined threshold value, the correction is not performed so that the erroneous correction can be prevented as well as the predetermined threshold value. The error correction capability can be improved by setting only the following bits as the error correction target.

In this example, the level detection program 1
Although 12a is explicitly provided between the autocorrelation value processing program 115 and the data acceptance program 11d, the function of the level detection program 112a is as a part of the autocorrelation value processing program 115 or one of the data acceptance program 11d. It may be embodied as a part or dispersed in both 115 and 11d.

[0066]

As is apparent from the above description, in the receiving apparatus of the present invention, the reliability judgment of received data is based on not only the maximum autocorrelation value but also the reception level in addition to the autocorrelation value. By doing so, there is an advantageous effect that the reliability of the received data can be promptly determined.

[Brief description of drawings]

FIG. 1 is a block diagram of a reader (data reading device) that is a first embodiment of a receiving device of the present invention and a data storage body of a communication partner device thereof.

FIG. 2 is a diagram of an example of the communication.

FIG. 3 is a block diagram of a reader (data reading device) that is a second embodiment of the receiving device of the present invention.

FIG. 4 is an example of sampling of the received signal.

FIG. 5 is a block diagram of a conventional reader and data storage body.

FIG. 6 is a detailed block diagram of a correlation calculation circuit.

[Explanation of symbols]

10 reader 11 microcomputer 11a start determination program 11b command transmission program 11c autocorrelation value processing program 11d data acceptance program 11e stop determination program 12 modulation circuit 13 transmission unit 14 M ₀ correlation calculation circuit (demodulation circuit) 15 M ₁ correlation calculation circuit ( Demodulation circuit 20 Data storage 21 Microcomputer 21a Command acceptance program 21b Data reading program 21c Data transmission program 22 Memory 23 Transmission unit 24 Demodulation circuit 25 Selection circuit 26 M ₀ generation circuit 27 M ₁ generation circuit 100 Reader 112 Level detection program 113 Start determination program 114 Stop determination program 115 Autocorrelation value processing program R Maximum autocorrelation value N Minimum autocorrelation value A Received signal level

Claims (12)

[Claims] 1. A receiving device for determining whether or not a received signal is a pseudo-random signal when receiving and communicating the pseudo-random signal, and calculating means for calculating an autocorrelation value of the pseudo-random signal. And a detection unit that detects a reception level of the pseudo-random signal, and a unit that makes the determination based on the autocorrelation value and the reception level. 2. A means for performing at least any one of a communication start determination, an error determination, and a stop / stop determination as the determination or in addition to or instead of the determination. 1. The receiving device according to 1. 3. The receiving device is a data reading device for reading stored data from a data storage body by communication of a pseudo-random coding system, and the read data is valid as the judgment or in addition to or instead of the judgment. 3. The receiving apparatus according to claim 1, further comprising means for determining whether or not there is any. 4. The receiving device according to claim 3, wherein the receiving device includes means for performing error correction on read data in accordance with a result of the determination. 5. A ratio between the maximum autocorrelation value of the autocorrelation value and the reception level exceeds a predetermined first threshold value (S0), and the maximum autocorrelation value is a predetermined second threshold value (TS).
The receiving device according to claim 1, wherein the reception signal is determined to be reliable when it is larger. 6. A ratio between the maximum autocorrelation value of the autocorrelation value and the reception level exceeds a predetermined first threshold value (S0), and the maximum autocorrelation value is obtained from a predetermined second threshold value (TS). 5. The received data is determined to be reliable when it is large and the minimum autocorrelation value of the autocorrelation values is smaller than a third threshold value (TN), according to any one of claims 1 to 4. Receiver. 7. A ratio between the maximum autocorrelation value of the autocorrelation value and the reception level exceeds a predetermined first threshold value (S0), and the maximum autocorrelation value and the minimum autocorrelation of the autocorrelation value. Determining that the received data is reliable when the ratio of the received data is larger than the ratio (TS / TN) of a predetermined second threshold value to the maximum autocorrelation value and a predetermined third threshold value to the minimum autocorrelation value. The receiving device according to any one of claims 1 to 4, wherein: 8. The first, second and third thresholds (S0, T
8. The receiving device according to claim 5, wherein at least one of S, TN, and TS / TN) is calculated according to the reception level. 9. The calculating means calculates an autocorrelation value of a set of orthogonal components from the pseudo-random signal using a pair of local oscillation signals whose phases are orthogonal to each other, and the detecting means comprises: The receiving apparatus according to any one of claims 1 to 8, wherein the receiving level is detected based on a set of orthogonal components. 10. The calculating means calculates a set of orthogonal components for calculating the autocorrelation value from the pseudo-random signal using a pair of local oscillation signals whose phases are orthogonal to each other. 9. The receiving apparatus according to claim 1, wherein the means detects the reception level based on the set of orthogonal components. 11. The calculating means calculates the autocorrelation value based on a sum of absolute values of respective orthogonal components of the set, and the detecting means calculates the reception level based on the sum. 11. The receiving device according to claim 10, wherein the receiving device detects. 12. The reception means calculates the average of absolute values of deviations from a predetermined reference level for a plurality of the sums based on the number of samplings corresponding to the sequence length of the pseudo random signal. The receiving device according to claim 11, wherein the receiving device detects a level.