Transponder and interrogator for communication system

[Technical field to which the invention belongs] In the present invention, the main carrier is transmitted from the interrogator, and the responder that receives the main carrier uses the interrogator to obtain a reflected wave in which the main carrier is modulated in a predetermined manner. Responding to communication system responders and interrogators.

[0002] Conventionally, a main carrier is transmitted from an interrogator to a plurality of responders, and the responder is a subcarrier in which the main carrier is modulated by a predetermined information signal such as a responder ID or an information signal. Radio communication systems that modulate and reflect are known (see, for example, Patent Document 1).

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2000-49656 [0004] [Problems to be Solved by the Invention] However, when the number of responders is large, the subcarrier frequencies of all the responders are different. It is difficult to do so in consideration of the reception / demodulation ability of the interrogator, and therefore, there is a problem that the possibility of collision increases because the available frequencies are limited. Further, even if the subcarrier frequency of the responder can be changed, there is a problem that the collision cannot be avoided because the responder cannot know which subcarrier the other responder is using. .. Furthermore, when there are multiple interrogators, even if the frequency of the transmitted wave from the interrogator is changed, the responder does not have frequency selectivity, so the transmitted wave is modulated and reflected by the response signal from the unexpected responder and returned. Therefore, there is a problem that the possibility of collision increases.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to realize a responder and an interrogator of a communication system in which a plurality of interrogators can simultaneously identify a plurality of responders. And.

[Means for Solving the Problems] In order to achieve this object, the responder of the communication system according to claim 1 transmits a main carrier wave from the interrogator and receives the main carrier wave. A responder of a communication system in which the device returns a reflected wave obtained by performing a predetermined modulation on the main carrier wave to the interrogator, and the responder receives the main carrier transmitted from the interrogator. A modulation subcarrier hopping means composed of a main carrier reception reflection means for reflection, a frequency hopping means for hopping the frequency of the subcarrier, and a subcarrier modulation means for modulating the subcarrier with a predetermined information signal. The frequency hopping means includes a main carrier modulation means that modulates the reflected wave when the main carrier receives and reflects the main carrier on the subcarrier that is modulated by the subcarrier. The configuration is characterized in that the frequency of the subcarrier is hopping using a hopping pattern corresponding to the unit data string of the information signal.

[0007] In the responder of the communication system having this configuration, the main carrier receiving and reflecting means receives and reflects the main carrier transmitted from the interrogator, and the frequency hopping means of the modulation subcarrier hopping means hops the frequency of the subcarrier. Then, the subcarrier modulation means of the modulation subcarrier hopping means modulates the subcarrier with a predetermined information signal, and the main carrier modulation means is the subcarrier modulated by the subcarrier modulation means and received by the main carrier reception reflection means. The reflected wave when reflecting the carrier wave is modulated, and the frequency hopping means hops the frequency of the subcarrier wave using a hopping pattern corresponding to a unit data string of the information signal.

[0008] Further, in the response device of the communication system according to claim 2, in addition to the configuration of the invention according to claim 1, the frequency hopping means has the number of bits or the number of bits constituting the unit data string of the information signal. It is characterized in that the frequency of the subcarrier is hopping by the number of symbols.

[0009] In the responder of the communication system having this configuration, in addition to the operation of the invention according to claim 1, the frequency hopping means has the number of bits or symbols constituting the unit data string of the information signal. Hopping the frequency of the carrier.

[0010] Further, in the response device of the communication system according to claim 3, in addition to the configuration of the invention according to claim 1 or 2, the number of bits constituting the unit data string is 8 bits or less. It is characterized by.

[0011] In the responder of the communication system having this configuration, in addition to the operation of the invention according to claim 1 or 2, the number of bits constituting the unit data string is 8 bits or less.

[0012] Further, in the responder in the communication system according to claim 4, in addition to the configuration of the invention according to any one of claims 1 to 3, the frequency hopping means corresponds to each hopping frequency of the hopping pattern. The frequency of the subcarrier is hopping so as to indicate a predetermined bit value or symbol value.

[0013] In the responder in the communication system having this configuration, in addition to the operation of the invention according to any one of claims 1 to 3, the frequency hopping means has a predetermined bit value corresponding to each hopping frequency of the hopping pattern. Alternatively, the frequency of the subcarrier is hopping so as to indicate the symbol value.

[0014] Further, in the responder in the communication system according to claim 5, in addition to the configuration of the invention according to claim 4, the predetermined bit value or symbol value is the predetermined bit value or symbol value. Bit position to indicate<u style="single">Subcarrier frequency corresponding to</u>Bit position different from<u style="single">Subcarrier frequency corresponding to</u>It is characterized in that it is the same as the bit value or symbol value of.

[0015] In addition to the operation of the invention according to claim 4, the responder in the communication system having this configuration has a predetermined bit value or symbol value as a bit position indicating a predetermined bit value or symbol value.<u style="single">Subcarrier frequency corresponding to</u>Bit position different from<u style="single">Subcarrier frequency corresponding to</u>It is the same as the bit value or symbol value of.

[0016] Further, in the responder in the communication system according to claim 6, in addition to the configuration of the invention according to any one of claims 1 to 5, the subcarrier modulation means uses the subcarrier as the responder. It is characterized in that it is modulated by frame data capable of identifying.

[0017] In addition to the operation of the invention according to any one of claims 1 to 5, the responder in the communication system having this configuration may identify the subcarrier to identify the responder. Modulate with possible frame data.

[0018] Further, in the responder in the communication system according to claim 7, in addition to the configuration of the invention according to claim 6, the frame data capable of identifying the responder is the identification of the responder. It is characterized in that it is a part of a code.

[0019] In the response device in the communication system having this configuration, in addition to the operation of the invention according to claim 6, the frame data capable of identifying the response device is a part of the identification code of the response device. is there.

[0020] Further, in the responder in the communication system according to claim 8, in addition to the configuration of the invention according to claim 6, the responder is provided with a random number generation means for randomly generating a number. The frame data capable of identifying the responder is characterized in that it is a number randomly generated by the random number generation means.

[0021] In addition to the operation of the invention according to claim 6, the responder in the communication system having this configuration is provided with a random number generating means for randomly generating a number to identify the responder. The frame data that can be generated is a number randomly generated by the random number generation means.

[0022] Further, in the responder of the communication system according to claim 9, in addition to the configuration of the invention according to claim 1 or 2, the frequency hopping means constitutes each of a predetermined bit value or symbol value. It is characterized in that the frequency of the subcarrier is hopping so that predetermined information can be transmitted by using a hopping pattern composed of a plurality of frequencies corresponding to the data values and the timing of hopping to each of the frequencies.

[0023] In the responder of the communication system having this configuration, in addition to the operation of the invention according to claim 1 or 2, the frequency hopping means corresponds to each data value constituting a predetermined bit value or symbol value, respectively. The frequency of the subcarrier is hopping so that predetermined information can be transmitted by using a hopping pattern composed of a plurality of frequencies to be used and the timing of hopping to each of the frequencies.

[0024] Further, in the responder of the communication system according to claim 10, in addition to the configuration of the invention according to claim 1 or 2, the frequency hopping means constitutes each of a predetermined bit value or symbol value. A plurality of time slots corresponding to each data value are provided, and data is transmitted according to the time slots.

[0025] In the response device of the communication system having this configuration, in addition to the operation of the invention according to claim 1 or 2, the frequency hopping means corresponds to each data value constituting a predetermined bit value or symbol value, respectively. A plurality of time slots are provided, and data is transmitted according to the time slots.

[0026] The interrogator in the communication system according to claim 11 is a reflection in which a main carrier is transmitted from the interrogator and a responder that receives the main carrier performs a predetermined modulation on the main carrier. A communication system interrogator that returns a wave to the interrogator, wherein a predetermined modulation is performed in the main carrier transmitting means for transmitting the main carrier and the responder.<u style="single">, The frequency of the subcarrier is hopping</u>Frame data is detected from the reflected wave receiving means for simultaneously receiving the entire hopping frequency band of the reflected wave, the demodulating means for demodulating the reflected wave received by the reflected wave receiving means, and the demodulated signal demodulated by the demodulating means. The frame data detecting means, the hopping pattern detecting means for detecting the hopping pattern of the reflected wave received by the reflected wave receiving means, the frame data detected by the frame data detecting means, and the hopping pattern detecting means detected. It is provided with a discriminating means for identifying the responder from the hopping pattern and discriminating the content of the information returned from the responder.

[0027] In the interrogator in the communication system having this configuration, the main carrier transmitting means transmits the main carrier, and the reflected wave receiving means is subjected to predetermined modulation in the responder.<u style="single">, The frequency of the subcarrier is hopping</u>The entire hopping frequency band of the reflected wave is received at the same time, the demodulating means demodulates the reflected wave received by the reflected wave receiving means, the frame data detecting means detects the frame data from the demodulated signal demodulated by the demodulating means, and the hopping pattern. The detecting means detects the hopping pattern of the reflected wave received by the reflected wave receiving means, and the discriminating means identifies the responder from the frame data detected by the frame data detecting means and the hopping pattern detected by the hopping pattern detecting means. And, the content of the information returned from the responder is determined.

[Embodiments of the Invention] Hereinafter, an embodiment embodying the communication system of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of the communication system 1, and FIG. 2 is a diagram showing the relationship between the main carrier wave and the reflected wave used in the communication system 1.

As shown in FIG. 1, the communication system 1 is composed of an interrogator 10 and responders 20, 21, 22 as an example. The main carrier FC1 is transmitted from the interrogator 10, and the main carrier FC1 is irradiated to the responders 20 to 22. The reflected wave f1 is returned from the responder 20, the reflected wave f2 is returned from the responder 21, and the reflected wave f3 is returned from the responder 22.

[0030] Each of the responders 20 to 22 secondarily modulates the received main carrier FC1 with the subcarrier signals fs1 to fs3 which are primary modulated by an information signal (data) such as a responder identification signal. The reflected waves f1 to f3 are returned. Specifically, as shown in FIG. 2, the frequency of the subcarrier signal is different for each responder and is frequency hopping. As shown in FIG. 2, the sideband signal of FC1 ± fs1, FC1 ± fs2, FC1 ± fs3 (the lower sideband is not shown) exists in the reception band of the interrogator 10, but the frequency. Since they are hopping, the probability that they will collide with each other is very small, so that the interrogator 10 can extract the information signal of the information signal from each of the responders 20, 21, and 22.

Next, the electrical configuration of the interrogator 10 will be described with reference to FIG. FIG. 3 is a block diagram showing the electrical configuration of the interrogator 10. As shown in FIG. 3, the interrogator 10 is composed of a digital circuit unit 30 and an analog circuit unit 40, and the analog circuit unit 40 includes an oscillator 41 that oscillates a main carrier wave having a frequency of 900 MHz, 2.4 GHz, 5 GHz, or the like. If necessary, the ID and hopping timing (not shown) of the interrogator are ASK modulated to modulate the main carrier oscillated by the oscillator 41, and the main carrier modulated by the modulator 42. The power amplifier 43 for power amplification and the output from the power amplifier 43 are transmitted to the antenna 47, and the radio wave received by the antenna 47 is transmitted to the low noise amplifier (hereinafter referred to as LNA) 45 described later. The circulator 44 that separates the output and the input, the LNA45 that amplifies the received signal from the responder received by the antenna 47, and the homodyne detection by mixing the received signal amplified by the LNA45 with the signal from the oscillator 41. It is composed of the main carrier demodulator 46 and the oscillator 46.

Further, the digital circuit unit 30 A / D-converts the received signal homodyne-detected by the main carrier demodulator 46 from an analog signal to a digital signal, and filters the A / D-converted received signal. A band division filter 32 that separates into channels corresponding to the hopping frequency, a subcarrier demodulator 33 that demodulates the subcarrier signal separated by the band division filter 32 to generate the original information signal, and a subcarrier demodulator 33. A frame divider 34 that separates the output from each channel generated by the above into appropriate frames, a pattern detector 35 that sorts the frames divided by the frame divider 34, and a frame sorted by the pattern detector 35. It is composed of a data demodulator 36 that connects the above to each responder in chronological order, and a controller 31 that controls the entire interrogator 10. The data signals connected in chronological order for each responder connected by the data restorer 36 are input to the controller 31.

[0033] Next, the structure of the responder 20 will be described with reference to FIG. FIG. 4 is a block diagram of the responder 20. As shown in FIG. 4, it is composed of a modulator / demodulator 60 connected to the antenna 61 and a digital circuit unit 50. The digital circuit unit 50 receives an information signal in which a controller 51 that controls the responder 20, a subcarrier oscillator 53 that oscillates a subcarrier, and a subcarrier oscillated by the subcarrier oscillator 53 are input via the controller 51. A subcarrier modulator 52 that modulates with phase modulation (PSK) is provided. The subcarrier modulated by the subcarrier 52 is configured to be input to the modulator / demodulator 60, modulate the main carrier received from the interrogator 10, and transmit it as a reflected wave from the antenna 61. The subcarrier oscillator 53 and the subcarrier modulator 52 may be configured in software by using the clock of the controller 51. Further, the modulation of the subcarrier may be frequency modulation (FSK) or 4-phase phase shift keying (QPSK) in addition to phase modulation (PSK). Further, the subcarrier oscillator 53 and the subcarrier modulator 52 may be provided in the controller and integrated into one chip. The responders 21 and 22 have the same configuration as the responder 20. Further, the responders 20 to 22 may be provided with a random number generation circuit.

Next, the operation of the communication system of the present invention configured as described above will be described with reference to FIGS. 1 to 10. FIG. 5 is a diagram showing the state of signals in each part of the interrogator 10 and the responders 20 and 21, and FIGS. 6 and 7 are conceptual diagrams showing the output of each channel of the returned wave from the responder. , FIG. 8 is a schematic diagram showing the output from each channel of the return wave from the response device of the second embodiment, and FIG. 9 is a schematic diagram showing the return wave from the response device of the third embodiment. FIG. 10 is a schematic diagram showing the output from each channel, and FIG. 10 is a schematic diagram showing the output from each channel of the return wave from the responder of the fourth embodiment.

[0035] First, the interrogator 10 oscillates the main carrier FC1 having frequencies such as 900 MHz, 2.4 GHz, and 5 GHz from the oscillator 41. The main carrier FC1 oscillated by the oscillator 41 is ASK modulated by the modulator 42 with information indicating the ID number of the interrogator, hopping timing, etc. as necessary under the control of the controller 31, and is subjected to ASK modulation via the circulator 44. Is transmitted from the antenna 47.

In the responder 20 that received the main carrier FC1 from the interrogator 10, the subcarrier oscillated by the subcarrier oscillator 53 is phase-modulated by the subcarrier modulator 52 by the information signal shown in FIG. 5 (a). Then, it becomes the subcarrier fs1 shown in FIG. 5 (b), and this subcarrier is applied to the modulator / demodulator 60.

The responder 21 that received the main carrier FC1 from the interrogator 10 also performs the same processing as the responder 20, and is oscillated by the subcarrier oscillator 53 by the information signal shown in FIG. 5 (c). When the subcarrier is phase-modulated by the subcarrier modulator 52, it becomes the subcarrier fs2 shown in FIG. 5 (d), and this subcarrier signal is applied to the modulator / demodulator 60.

[0038] The subcarriers fs1 and fs2 have a frequency arrangement as shown in FIG. 5 (e) (the horizontal axis represents the frequency, and the origin "0" represents the frequency 0 Hz). Then, in the responder 20, the modulator / demodulator 60 reflects the main carrier FC1 by amplitude modulation or phase modulation with the subcarrier signal fs1, and is radiated from the antenna 61. The radio wave radiated from the antenna 61 has a spectrum as shown in FIG. 5 (f) (Note that the spectrum shown in FIG. 5 (f) shows only the upper sideband with respect to FC1. The sideband on the side is omitted.) In FIG. 5 (f), FC1 shows the main carrier from the interrogator 10, FC1 + fs1 shows the reflected wave f1 from the responder 20, and FC1 + fs2 shows the reflected wave f2 from the responder 21. ..

Next, in the interrogator 10, the received signal from the responder is amplified by the LNA 45 via the circulator 44, and in the main carrier demodulator 46, the signal from the oscillator 41 is mixed to perform homodyne detection. .. The reception band is selected as a band that includes the sideband band of the highest hopping frequency and does not include the adjacent main carrier frequency. This is because when the adjacent main carrier band is included, the intensity of this main carrier is much higher than that of the reflected wave modulated and reflected by the responder, so that the intensity of the reflected wave is relatively low and the S / N ratio is poor. Because.

[0040] When homodyne detection is performed, as shown in Fig. 5 (g), a signal in which the subcarrier signal of fs1 of the reflected wave from the responder 20 and the subcarrier signal of fs2 of the reflected wave from the responder 21 are mixed. Is demodulated. This signal is converted into a digital value by an A / D converter (not shown) built in the band dividing filter 32, and the subcarrier signal and response of the reflected wave fs1 from the responder 20 are processed by the band dividing filter 32. The subcarrier signal of the reflected wave fs2 from the device 21 is filtered by Fourier conversion, separated into channels corresponding to the hopping frequency (CH1, CH2, CH3, ...), And the separated signals are reversed. When converted into a time series by Fourier conversion, the subcarrier signal of the reflected wave fs1 from the responder 20 is taken out as a modulated subcarrier signal as shown in FIG. 5 (h). Further, the subcarrier signal of the reflected wave fs2 from the responder 21 is taken out as a modulated subcarrier signal as shown in FIG. 5 (i). Actually, the numerical strings corresponding to the waveforms shown in FIGS. 5 (h) and 5 (i) are taken out. Here, the frequency hopping timing signal may be transmitted to the responders 20 and 21 by the ASK modulation in the modulator 42 of the interrogator 10. As a result, the responders 20 and 21 perform frequency hopping each time a timing signal is received. The reflected waves from the responders 20 and 21 received by the interrogator 10 are homodyne-detected by the main carrier demodulator 46 and then A / D-converted. If the data blocks are divided accordingly and the Fourier transform process and the inverse Fourier transform process are performed on the data block, the frame division process described later can be easily performed.

[0041] When the subcarrier frequency is hopping, the subcarrier signal is output from a different channel for each hopping. The original information signal is extracted by demodulating each of these with the subcarrier demodulator 33. Specifically, in the reflected wave fs1 from the responder 20, the information signal of the waveform shown in FIG. 5 (j) is demodulated from the waveform shown in FIG. 5 (h), and in the reflected wave fs2 from the responder 21, the figure is shown. The information signal of the waveform shown in FIG. 5 (k) is demodulated from the waveform shown in 5 (i).

Since information signals from the subcarrier signals switched for each frequency hopping are output one after another from each channel, the output from each channel can be transmitted by only one subcarrier by the frame divider 34. It is separated into frames, which are data units, and the data of each frame (hereinafter abbreviated as frame data) is detected, and the pattern detector 35 detects the output from each channel and the hopping pattern from the frame data, and restores the data. The device 36 restores the data related to the original information signal using the hopping pattern and the frame data, and inputs the data to the controller 31.

Next, the outputs of the reflected waves from the responders 20 and 21 from each channel will be described with reference to FIG. FIG. 6 is a schematic diagram showing the output from each channel, where CH1 indicates channel 1, CH16 indicates channel 16, and the numbers in the square frame identify the responders 20 and 21. Indicates the responder ID, which is an identification code for the device, h1 indicates the "first frequency", and h16 indicates the "16th frequency". Further, FIG. 6 shows an example in which the responder IDs of the responders 20 and 21 are 4 bits, and the minimum data unit to be transmitted is 4 bits.

[0044] In the example shown in FIG. 6, the hopping start frequency differs depending on the lower two bits of the responder ID. Further, the hopping frequency is different depending on the bit value of the transmission data. Since the lower 2 bits of the responder ID "0100" are 00, hopping is started from h1 or h2. If the bit of the first data is "0", hopping is started from the frequency h1. If the bit of the first data is "1", hopping is started from the frequency h2. After that, similarly, whether the hop frequency is h3 or h4 is determined by the value of the bit to be transmitted next. The frequencies used thereafter are predetermined for each set of 0 or 1 such as h5 and h6. Therefore, the hopping pattern is hl or h2 h3 or h4 h5 or h6 h7 or h8. Questioner 10 detects that the hopping pattern is hl h3 h6 h7, and restores it when the data is 0010.

[0045] Similarly, when the responder ID is "1011", hopping starts from h8, and when the hopping pattern is h8 h10 h11 h14, the restored data is 1101. Since the responder ID is repeatedly transmitted at each frequency, even if an error occurs in some frequencies, it can be easily identified. Since the reflected waves from the responders 20 and 21 are weak, an error is likely to occur during demodulation. However, in this method, for example, if it is possible to determine whether the subcarrier is detected at the frequency h3 or h4, it does not depend on the demodulation. Since the data can be restored, extremely sensitive reception is possible. Here, it was explained that hopping is performed in the order of subscripts such as h1, h2, h3, etc. However, since these frequencies are randomly assigned to each channel, the actual hopping frequency is random. Since the transmission time of the minimum data at one time (residence time at a specific frequency) is extremely short, the probability of collision with other responders is very small. Also, even if the lower two bits are the same, there are multiple start frequencies (such as h1, h9, ... for 00), so if the hopping start frequency is randomly selected, the collision probability can be further reduced. In the above example, the case where the minimum data is 4 bits has been described, but the same applies to 8 bits and 16 bits.

As shown in FIG. 7, the number of hopping corresponding to the number of bits is set as an even channel 1 and an odd channel 0, and the even channel and the odd channel are paired to form a subcarrier. You may do hopping. Further, the minimum data may be 1 bit. For example, if an ID is sent with a sensor, a switch, or the like with hopping on only for even-numbered channels and hopping off only for odd-numbered channels, the state of the sensor can be detected only by detecting the hopping channel to which the ID has been sent. Further, it is not necessary to send the responder ID in each channel as long as the responder can be distinguished. Further, even if the responder ID is 4 bits or more, it may be sent as it is. Further, a random number generation circuit that randomly generates a 4-bit value may be provided, and the 4-bit value generated by the random number generation circuit may be transmitted. In that case, you may send your ID and data in order for each minimum amount of data according to the hopping pattern.

[0047] Next, a second embodiment of the output from each channel will be described with reference to FIG. FIG. 8 is a schematic diagram showing the output from each channel of the second embodiment. As shown in FIG. 8, if the responder ID is 0010, hopping is started from h3. At first, only the responder is identified from the start position. A 4-bit identification code is assigned to frequencies h1, h2, .... After that, starting from here, the value of the information bit is "0" if the subscript of h is odd, and "1" if it is even). In h3, the value "0" of the data bit to be sent next is sent. Since h5 is next to h3, the bit value is "0". In h5, the next value "1" is sent. Next is h8, but even if subcarriers are observed in h7 due to noise, it can be judged as "1" from the data transmitted in the previous h5. Since the bit value at the bit position different from the bit position specified by the hopping frequency of the hopping pattern for restoring data is transmitted, even if an error occurs, it can be compensated. The transmitted data "0" and "1" may be "0" if there is phase inversion in the frame, and may be "1" if there is no phase inversion. Further, "0" and "1" may be determined based on the number of phase inversions in the frame (since the inversion period is known, pulse-like inversion due to noise or the like is ignored). As a result, the above method has a feature that an error is unlikely to occur because it is a simple determination method.

[0048] Next, a third embodiment of the output from each channel will be described with reference to FIG. FIG. 9 is a schematic diagram showing the output from each channel of the third embodiment. As shown in FIG. 9, a specific hopping pattern may be associated with a specific code. The responder ID may be sent in a frame. The responder ID may be identified at the start position as in FIG. Data can be discriminated from relative patterns. As a result, the probability that a bit error will occur can be made much lower by detecting the rehopping pattern than when demodulating the data. Data may be sent in frames and IDs may be identified by patterns. This allows long responder IDs to be identified. Further, of the responder ID and the transmission data, the longer one may be sent as a hopping pattern and the shorter one may be sent as the data in the frame. Since hopping is performed in a shorter cycle, it is less susceptible to interference from interfering waves and the like, and reliability is improved.

Next, a fourth embodiment of the output from each channel will be described with reference to FIG. FIG. 10 is a schematic diagram showing the output from each channel of the fourth embodiment. As shown in FIG. 10, even if the hopping frequency is not distinguished according to "0" and "1", a time slot is provided and the data is restored according to which time slot the responder sent the data. Is also good. In FIG. 10, when the subscript of t is an accidental timing, it is restored as "1", and when the subscript of t is an odd timing, it is restored as "0". This is effective when you cannot get a lot of hopping frequencies. Furthermore, since the amount of data transmitted at one time is small, the data may be restored from the time difference until the start of the frame instead of the time slot (pulse position modulation method). The time slot method shown in FIG. 10 is binary, but multi-valued data such as 2 bits can be restored at the same time by changing a plurality of frame start positions.

[0050] Since subcarrier hopping is not a technique limited to the responder for the microwave band, a wireless tag using a frequency such as 13.56 MHz or 125 kHz as the main carrier wave, that is, the antenna is coiled and electromagnetic induction is performed. It may be used for exchanging data with.

Further, in the above-described embodiment, the frequency of the subcarrier is hopping by the number of bits constituting the unit data string of the information signal, but the number of bits constituting the unit data string of the information signal is 32 bits or 64 bits. In some cases, the frequency of the subcarrier may be hopping by the number of symbols having a plurality of bits as one unit.

[0052] Further, in the above-described embodiment, an example in which a predetermined bit value is assigned corresponding to each frequency is shown, but a predetermined symbol value may be assigned corresponding to each frequency. For example, in Fig. 6 etc., two frequencies are considered as a group and 0 and 1 are assigned, but four frequencies are considered as one group and 2 bits (that is, 00, 01, 10, 11) are assigned according to a predetermined rule. You may.

[0053] Further, in the above-described embodiment, an example in which bit values are assigned corresponding to each timing is also shown, but similarly, a predetermined symbol value may be assigned corresponding to each timing. For example, in Figure 10, two timings are considered as one group and 0 and 1 are assigned, but eight timings are considered as one group and 3 bits (that is, 000, 001, ..., 111) are set as a predetermined rule. May be assigned with.

[Effect of the Invention] As is clear from the above description, in the responder of the communication system according to claim 1, the main carrier receiving and reflecting means receives and reflects the main carrier transmitted from the interrogator, and is a modulation subcarrier hopping means. The frequency hopping means hopping the frequency of the subcarrier, the subcarrier modulation means of the modulation subcarrier hopping means modulates the subcarrier with a predetermined information signal, and the main carrier modulation means is the subcarrier modulated by the subcarrier modulation means. The main carrier receiving and reflecting means modulates the reflected wave when reflecting the received main carrier, and the frequency hopping means can hopping the frequency of the subcarrier by using a hopping pattern corresponding to a unit data string of the information signal. Therefore, a plurality of responders can be identified at the same time, and even if the plurality of responders transmit at the same time, the probability of collision becomes very small, and control such as time-delayed transmission for avoiding collision becomes unnecessary. Further, the control of the transmission of the plurality of responders from the interrogator becomes unnecessary, and the control such as stopping the transmission from the detected responder or transmitting after specifying the responder ID becomes unnecessary. Further, since the data string can be detected by the hopping pattern, processing such as error correction is easy, and data restoration is easy.

[0055] Further, in the responder of the communication system according to claim 2, in addition to the effect of the invention according to claim 1, the frequency hopping means has the number of bits or the number of bits constituting the unit data string of the information signal. Since the frequency of the subcarrier is hopping by the number of symbols, the hopping pattern is simple and the data can be easily restored.

[0056] Further, in the responder of the communication system according to claim 3, in addition to the effect of the invention according to claim 1 or 2, the number of bits constituting the unit data string is 8 bits or less. The hopping pattern is simple and data recovery is easy.

[0057] Further, in the responder in the communication system according to claim 4, in addition to the effect of the invention according to any one of claims 1 to 3, the frequency hopping means corresponds to each hopping frequency of the hopping pattern. Since the frequency of the subcarrier is hopping so as to indicate a predetermined bit value or symbol value, the transmission data can be provided with redundancy and is resistant to errors.

[0058] Further, in the responder in the communication system according to claim 5, in addition to the effect of the invention according to claim 4, the predetermined bit value or symbol value is a bit indicating a predetermined bit value or symbol value. position<u style="single">Subcarrier frequency corresponding to</u>Bit position different from<u style="single">Subcarrier frequency corresponding to</u>Since it is the same as the bit value or symbol value of, it is possible to give redundancy to the transmitted data, and even if an error occurs, it can be restored.

[0059] Further, in the responder in the communication system according to claim 6, in addition to the effect of the invention according to any one of claims 1 to 5, the subcarrier modulation means uses the subcarrier as the responder. Can be modulated by frame data that can identify.

[0060] Further, in the responder in the communication system according to claim 7, in addition to the effect of the invention according to claim 6, the frame data capable of identifying the responder is the identification of the responder. Since it is a part of the code, the amount of transmitted data is small, so the amount of error occurrence is small.

[0061] Further, in the responder in the communication system according to claim 8, in addition to the effect of the invention according to claim 6, the responder is provided with a random number generation means for randomly generating a number. Since the frame data that can identify the responder is a number randomly generated by the random number generation means, the amount of transmitted data is small and frequency collision is unlikely to occur, so that the amount of error is small. Become.

[0062] Further, in the responder of the communication system according to claim 9, in addition to the effect of the invention according to claim 1 or 2, the frequency hopping means has each data constituting a predetermined bit value or symbol value. Using a hopping pattern consisting of multiple frequencies corresponding to each value and the timing of hopping to each frequency, the frequency of the subcarrier can be hopping so that predetermined information can be sent, so that a large number of hopping frequencies cannot be obtained. It is also effective and can identify the identification code of a long responder.

[0063] Further, in the responder of the communication system according to claim 10, in addition to the effect of the invention according to claim 1 or 2, the frequency hopping means has each data constituting a predetermined bit value or symbol value. Since a plurality of time slots corresponding to the values are provided and data can be transmitted according to the time slots, it is possible to easily identify the responder even when a large number of hopping frequencies cannot be obtained.

[0064] Further, in the interrogator in the communication system according to claim 11, the main carrier transmitting means transmits the main carrier, and the reflected wave receiving means is subjected to predetermined modulation in the responder.<u style="single">, The frequency of the subcarrier is hopping</u>The entire hopping frequency band of the reflected wave is received at the same time, the demodulating means demodulates the reflected wave received by the reflected wave receiving means, the frame data detecting means detects the frame data from the demodulated signal demodulated by the demodulating means, and the hopping pattern. The detecting means detects the hopping pattern of the reflected wave received by the reflected wave receiving means, and the discriminating means identifies the responder from the frame data detected by the frame data detecting means and the hopping pattern detected by the hopping pattern detecting means. Since the content of the information returned from the responder can be determined, it is possible to cope with the quick frequency hopping of the responder.

BRIEF DESCRIPTION OF THE DRAWINGS [0065] FIG. 1 is a diagram showing an example of a configuration of a communication system 1.

FIG. 2 is a diagram showing a relationship between a main carrier wave and a reflected wave used in the communication system 1.

FIG. 3 is a block diagram showing an electrical configuration of the interrogator 10.

FIG. 4 is a block diagram of responders 20, 21, and 22.

[Fig. 5] Fig. 5 shows the questioner 10.<u style="single">as well as</u>It is a figure which shows the state of the signal in each part of the responder 20, 21.

FIG. 6 is a conceptual diagram showing the output of each channel.

FIG. 7 is a conceptual diagram showing the output of each channel.

FIG. 8 is a schematic diagram showing the output from each channel of the second embodiment.

FIG. 9 is a schematic diagram showing the output from each channel of the third embodiment.

FIG. 10 is a schematic diagram showing outputs from each channel of the fourth embodiment.

[Code description] 1 Communication system 10 Questioner 20,21,22 Responseer 30 Digital circuit section 32 Band division filter 33 Subcarrier demodulator 34 Frame divider 40 Analog circuit section 41 Oscillator 42 Modulator 43 Power amplifier 45 LNA46 Main Carrier demodulator 47 Antenna 50 Digital circuit 51 Controller 52 Subcarrier modulator 53 Subcarrier oscillator 60 Modulator 61 Antenna