JP3978454B2 - High frequency radio - Google Patents

Description

The present invention relates to a high-frequency radio apparatus suitable for use by, for example, a short-range wireless communication system.
In this specification, the “short-range wireless communication system” means, for example, a keyless entry, wireless monitoring of a target or wireless control or other relatively close proximity using a carrier signal of weak power that is not subject to legal regulations. This is a general term for wireless communication systems performed at a distance.

  A keyless entry control system is known as an example of a system using a short-range wireless communication system. A keyless entry control system is a system that controls, for example, opening / closing of a door of a vehicle as a target object, engine start or engine stop, etc. wirelessly from a position several meters to several tens of meters away. A fixed wireless device and a portable wireless device possessed by the user.

FIG. 8 shows a schematic configuration example of such a conventional keyless entry control system.
In the example shown in FIG. 8, the transmitter 1 which is a radio carried by the user uses a carrier band signal having a frequency equal to or higher than the VHF band as an identification code of the transmitter 1 and an instruction signal for instructing opening / closing of the door, for example. And is transmitted from the antenna 5 toward the receiver 2 which is a fixed type radio device.

  The receiver 2 has an antenna filter for filtering the received carrier band signal to remove unnecessary frequency components. In a keyless entry control system, a frequency of a bandwidth necessary for communication (hereinafter referred to as “communication frequency”) has recently been used as a high-frequency signal of 315 [MHz]. Therefore, a surface acoustic wave filter (hereinafter referred to as “SAW filter”) 6 suitable for high frequency applications is generally used as the antenna filter of the receiver 2.

Further, according to the Radio Law Enforcement Regulation, the electric field strength at a point 3 m away from the transmitter 1 is not restricted if it is 500 [μV / m] or less per meter. Since the receiver 2 receives the carrier band signal transmitted with such weak power, the high frequency amplifier (preamplifier) 14 amplifies the carrier band signal, and the amplified carrier band signal is amplified. Then, the reception mechanism 4 directly detects and demodulates the identification code and the instruction signal. Then, various drive mechanisms of the vehicle are controlled in accordance with this instruction signal to open and close the door.
The receiving mechanism 4 can be made into an IC, and the receiver 2 is miniaturized by being mounted on the set substrate as a so-called discrete component together with the SAW filter 6.

In general, the relationship between the noise level N (W) and the bandwidth B (Hz) of a receiver directly detected using an antenna filter is uniquely determined by the following equation (1).
N = KTBF (1)

In the equation (1), K is a Boltzmann constant (1.38 × 10 ⁻²³ ), T is an absolute temperature (degree K), and F is a noise figure (W) of the receiver. Since the Boltzmann constant K, the absolute temperature T, and the noise figure F are constant values, the noise level N depends on the bandwidth B of the antenna filter. That is, the noise level N increases as the antenna filter having a wider bandwidth B is used, and the reception sensitivity of the signal component decreases accordingly. Further, since the bandwidth B is wide, mutual interference with unnecessary external signals is also caused, and malfunction is likely to occur.

  The frequency-attenuation characteristics when the SAW filter 6 is used as the antenna filter are as shown in FIG. That is, the bandwidth W1 in the 3 dB attenuation region is normally about 1000 [kHz]. On the other hand, for example, when the bit rate of the identification code is 1.2 [Kb / s], the bandwidth W2 required for communication is 4 [kHz] or less.

  As described above, since the SAW filter 6 has a very wide bandwidth (about 1000 [kHz]) with respect to the bandwidth (4 [kHz]) necessary for communication, as is apparent from the equation (1). It is essentially impossible to reduce the noise level N and increase the reception sensitivity of the signal component. In other words, the range in which the receiver 2 can communicate with the transmitter 1 (for example, communication distance) has a certain limit.

  Further, since the bandwidth B of the SAW filter 6 cannot be reduced, not only can the mutual interference between the external signal and the communication frequency (the frequency of the signal necessary for communication, hereinafter the same) be effectively prevented, The image frequency relative to the communication frequency cannot be removed, and the communication quality cannot be improved. In order to remove the image frequency, it is necessary for the reception mechanism 4 to have a function like an image suppression unit. Therefore, the configuration of the reception mechanism 4 cannot be simplified, and power consumption cannot be reduced. There was a problem.

  Furthermore, since the SAW filter 6 has a structure in which a plurality of electrodes are mounted on the surface of a quartz plate, the SAW filter 6 is relatively expensive, and must be mounted on the set substrate as a separate body from the IC receiving mechanism 4. Therefore, there is a certain limit to the miniaturization of the receiver 2.

  Note that in a short-range wireless communication system such as the keyless entry control system described above, particularly in a system using the SAW filter 6 as an antenna filter, one antenna filter is not used for both transmission and reception. This is because even in the same carrier band signal, the transmission frequency f1 and the reception frequency f2 of the communication frequencies are different, and the bandwidth B of the SAW filter 6 is very wide. When the high-frequency signal before being filtered in step A is amplified, the level of the carrier band signal other than the bandwidth necessary for communication increases, and adversely affects the SAW filter 6 (for example, the operation becomes unstable and the specified filter The reason is that the characteristic cannot be obtained).

  An object of the present invention is to provide a small high-frequency radio that can expand the range of communication, can effectively prevent mutual interference with external signals, and can easily realize suppression of image frequency. There is to do.

  The present invention pays attention to the relationship between the noise level and the bandwidth of the above-described formula (1), and provides a high-frequency radio that employs a quartz filter that has a very narrow band as an antenna filter compared to a conventional SAW filter. Is. According to the crystal filter, the bandwidth through which the carrier band signal passes can be set to a bandwidth of 10 [kHz], for example, 20 [kHz] or less. Therefore, the bandwidth of the SAW filter is about 1000 [kHz]. Compared to what happened, the band becomes much narrower. Therefore, the receiving sensitivity on the receiving side for the same energy (power at the time of transmission) can be dramatically increased by the law of energy conservation.

Conventionally, a crystal filter has been widely used in a radio device having a relatively low frequency up to a short wave band, but this is used in a VHF band (30 to 300 [MHz]) or a UHF band (300 [MHz] to 3 [GHz]). It was unthinkable to use at a frequency of.
For example, as shown in FIG. 7 published in “Explanation and Application of Quartz Devices” (published by the Japan Quartz Device Industry Association, March 2002) p23, there is a certain upper limit to the feasible range of the quartz filter. Therefore, the antenna filter used for applications in the VHF band or higher, such as a keyless entry control system, was considered to be limited to SAW devices (SAW filters) developed for the high frequency band. It is the reason.
However, the manufacturing and processing technology of the crystal piece constituting the crystal filter is evolving day by day, and the range of frequencies in which the crystal filter can be used tends to be expanded. In addition to the fundamental wave, the crystal can be used at an overtone, that is, at a frequency that is an odd multiple of the fundamental wave frequency. The present inventors who are involved in the development of quartz / SAW-related devices have found that a crystal filter (crystal piece) can be used as an antenna filter even at a frequency higher than the VHF band by changing the conventional idea. is there.

A specific configuration aspect of the high-frequency wireless device provided by the present invention includes a wireless module that performs short-range wireless communication using weak power that is not subject to legal regulations by a carrier band signal in the UHF band, and a communication partner device through the wireless module. And a processing means for processing a signal passed between them.
The radio module filters the carrier band signal after high frequency amplification at the time of reception, and transmits and receives a crystal band filter for filtering the carrier band signal of the same frequency as the received carrier band signal before the high frequency amplification at the time of transmission, and for direct detection And a crystal resonator that oscillates a local signal for direct modulation, and the crystal filter has a frequency deviation direction that is the same as a frequency deviation direction during detection or modulation by the local signal. It works in the environment.
The processing means generates a signal that is directly modulated based on spread-modulated data obtained by spreading with a spreading code determined with a communication partner at the time of transmission, and a signal directly detected at the time of reception. The signal obtained by despreading the spreading code is demodulated.
“Operating in the same environment” means that, for example, a crystal filter and a crystal resonator are operated in one module container made of a material having substantially the same temperature characteristics.

In the direct detection type radio frequency radio apparatus, the circuit configuration is simplified and the miniaturization can be promoted as compared with the superheterodyne system in which the received signal is detected at an intermediate frequency and then detected. Since the crystal filter is used for both transmission and reception, the structure can be simplified and versatility can be improved. In addition, it can take advantage of the characteristics of the crystal filter that the bandwidth is extremely narrow and image suppression is possible by itself, so that the reception sensitivity can be increased despite the weak power, and the communication range can be expanded. it can. From the viewpoint of reducing power consumption, the carrier band signal is an intermittent signal.
In the case of reception, for example, by adjusting the amplification gain of the high-frequency signal before filtering, the image frequency can be reliably removed at the stage of passing through the crystal filter, so that an image suppression unit or the like in the signal processing circuit in the subsequent stage is unnecessary. Thus, power consumption can be reduced accordingly. In the case of transmission, since the image frequency is suppressed by the crystal filter and then amplified to a predetermined power by the high frequency amplification unit at the final stage, amplification of the image frequency can be avoided.

The crystal filter in the high-frequency radio of the present invention is preferably housed in a single module container in which the temperature characteristics and aging characteristics are substantially the same as the temperature characteristics and aging characteristics of the crystal resonator.
As mentioned above, the bandwidth of the crystal filter is narrow, so if the ambient temperature changes or the frequency shifts due to aging (characteristic change) due to long-term use, direct detection is performed by the local signal oscillated from the crystal unit. There is a risk that inconvenience may occur. Therefore, by operating in an environment where the above characteristics of the crystal filter and the crystal resonator are substantially the same, even if a frequency shift occurs, the direction of the shift is the same. Inconvenience can be avoided.

  From the viewpoint of miniaturization, simplification, and versatility, the module container includes other components of the wireless module and the processing means.

    In the above high-frequency radio, when the carrier band signal having the same frequency is used, the processing means detects, for example, the difference between the frequency of the signal component included in the received carrier band signal and the frequency of the local signal of the own apparatus. The frequency difference data representing the detected frequency difference is recorded in a predetermined memory, and the frequency difference data is read from the memory when the signal to be transmitted to the communication partner is modulated. And a correction circuit for correcting the frequency of the carrier band signal for transmission.

In one embodiment, the processing means is a software radio that operates in cooperation with a processor and software existing in a predetermined storage area, or whose processing operation is performed by predetermined firmware, The operation content can be changed afterwards.
Software / radio enables wireless communication by changing software contents or firmware specifications even with other parties with different communication procedures and communication frequencies, so a single high-frequency radio can support various wireless communication systems. become able to.

  Since a quartz filter is used instead of the SAW filter as the antenna filter of the high-frequency radio, the bandwidth can be narrowed and the reception sensitivity can be increased. This makes it possible to expand the communication range and prevent mutual interference. .

Hereinafter, an embodiment when the present invention is applied to a high-frequency radio for performing a short-range wireless communication system will be described.
FIG. 1 shows the simplest configuration example when the high-frequency radio apparatus of the present invention is used as a receiver, and corresponds to FIG. 8 showing a conventional example. In FIG. 1, components having substantially the same functions as those shown in FIG. 8 are denoted by the same reference numerals for convenience of explanation.
The receiver 2 of this embodiment employs a direct detection method that does not depend on subcarriers, and includes a high-frequency amplifier (preamplifier) 14, a crystal filter 3, and a receiving mechanism 4. The high frequency amplifying unit 14 and the receiving mechanism 4 are composed of integrated IC chips (bare chips), and are housed in a module container and integrated with the crystal filter 3. Hereinafter, such an IC chip is referred to as an RF (Radio Frequency) IC chip.

The RFIC chip has, for example, a processor and a memory area. In the memory area, software (program, various parameters, and parameters) for the processor to read the digital signal processing for wireless communication with the transmitter 1 is read. Data) is a kind of software radio. The software can be rewritten even after it is manufactured as an RFIC chip by a data rewrite device (for example, a ROM writer) (not shown) so that it can communicate with other parties having different wireless communication procedures and communication frequencies. It is like that.
As the RFIC chip 7, in addition to software that can be rewritten later, firmware whose operation procedure is fixedly determined in advance, for example, a wiring board or a DSP (Digital Signal Processor) can be used. When using firmware, it is desirable that the firmware be exchangeable depending on the application.

The configuration of the receiving mechanism 4 is arbitrary, but if it includes a local oscillator having a crystal resonator that oscillates a high-frequency local signal for direct detection, the components of the local oscillator excluding the crystal resonator are included in the RFIC chip. At the same time, the quartz resonator is packaged in the module container together with the RFIC chip. In this way, the temperature and aging characteristics of the crystal filter 3 and the crystal resonator are substantially the same, so that the ambient temperature of the crystal filter 3 increases or the crystal piece ages. Even if the frequency is shifted due to the change, the frequency at the time of detection is also shifted in the same direction, so that the occurrence of inconvenience can be avoided. When importance is attached to aging characteristics, the same material may be used for materials other than quartz, for example, electrodes and adhesive members, which constitute both the quartz filter 3 and the quartz resonator.
The size of the crystal filter 3 and the crystal resonator is, for example, 315 [MHz] used in the keyless entry control system or a frequency band around it, and the size of the crystal piece is as small as about 1 mm square. Accommodating is extremely easy, leading to a reduction in size and mass productivity.

The module container has a container body 8 made of, for example, a laminated ceramic, as shown in a sectional view in FIG. However, any material other than the multilayer ceramic may be used as long as the temperature characteristics of the various parts accommodated in the container are substantially the same. The container body 8 is formed in a cross-sectional H shape having recesses on both sides. The crystal filter 3 is electrically and mechanically connected to the bottom surface of one concave portion of the molded container body 8 by a conductive adhesive 13 or the like, and the cover 15 is joined to the opening by seam welding or the like. It has become. When a crystal resonator is bundled, it is fixed to the container body 8 by the same method.
The RFIC chip 7 is fixed to the bottom surface of the other concave portion of the container body 8 by flip chip bonding or the like. The periphery of the RFIC chip 7 is usually filled with a protective resin 16 to prevent the RFIC chip 7 from being displaced when the receiver 2 is moved. The electrodes of the RFIC chip 7 and the electrodes of the crystal filter 3 (and the crystal resonator) are wired through, for example, through holes 17. Note that terminals (not shown) for surface mounting are formed on the upper surface of the frame forming the other recess.

FIG. 3A is a plan view of a crystal filter used in this embodiment, and FIG. The crystal filter 3 has, for example, an AT-cut crystal piece 9, and a pair of input / output electrodes 10 a and 10 b are attached to one main surface of the crystal piece 9. One common electrode 11 is attached to the other main surface of the crystal piece 9. From the input / output electrodes 10a and 10b and the common electrode 11, the extraction electrode 12 extends in a diagonal portion.
The AT-cut is cut parallel to the X-axis of the crystal and around 35 degrees 15 minutes from the Z-axis, and the frequency-temperature characteristics are known to exhibit extremely good cubic curves over a wide temperature range. Yes. As the crystal filter 3, for example, a third-order overtone, that is, 100 to 130 [MHz], preferably 105 [MHz] that has appeared on the market is used at 315 [MHz].

  In the receiver 2 having such a configuration, as shown in the frequency-attenuation characteristic diagram of FIG. 4, the bandwidth W1 in the 3 dB attenuation region of the crystal filter 3 is 20 [kHz] or less. Compared with the bandwidth (about 1000 kHz) of the conventional SAW filter 6, it becomes about 1/50 or less. Therefore, the noise level is approximately 1/50 compared to the case where the SAW filter 6 is used from the above-described equation (1). When compared with the reception sensitivity, a sensitivity increase of 17 dB (about 50 times) is obtained as compared with the case where the SAW filter 6 is applied. As a result, the range in which communication can be performed at a shorter distance than before can be expanded.

  Further, since the bandwidth is narrowed, interference with an external signal is prevented, and the image frequency is reliably suppressed, so that malfunction can be avoided. Furthermore, since the crystal filter 3 and the RFIC chip 7 of the receiving mechanism 4 are accommodated in the same module container, it is possible to promote downsizing.

In addition, although the container main body 8 of the module container has shown the example which provided the recessed part of the double-sided side, accommodated separately the crystal filter 3 and the RFIC chip 7, it provided the recessed part only in the one surface side, and both were shown. It may be accommodated, or both may be accommodated in separate containers and joined together.
In addition, although the crystal filter 3 has a third-order overtone, it may be a fundamental wave, and the order of the overtone is arbitrary.

<< Other embodiments >>
In the above example, a high-frequency radio is applied to the receiver 2, but it may be possible to respond to this after receiving a communication frequency from the transmitter 1, for example. An example of implementation is given.
FIG. 5 is a configuration diagram of a wireless module in which a transmission / reception high-frequency radio is accommodated in one module container and modularized. The wireless module 100 roughly includes a high frequency amplifying unit, a filter unit, and a signal processing unit (# 1).

  The high frequency amplification unit includes a low noise amplifier 102 that amplifies the carrier band signal received through the antenna connection terminal T11, and a power amplifier 103 that amplifies the power of the carrier band signal supplied through the antenna connection terminal T11 to a predetermined value. .

The filter unit includes a crystal filter 105. The crystal filter 105 is the same as the crystal filter 3 described above. For example, the center frequency of the bandwidth used for communication is 315 [MHz] and the bandwidth is 20 [kHz]. Since the bandwidth can be narrowed to, for example, 20 [kHz] or less by the crystal filter 105, when directly detecting an intermediate frequency of, for example, about 100 [kHz], the gain of the low noise amplifier 102 is reduced to, for example, low distortion. By adjusting the gain (about 15 [dB]), the image frequency can be reliably removed at the stage of the crystal filter 105, and an image suppression unit or the like in the signal processing circuit including the detection circuit 107 at the subsequent stage is unnecessary. can do. Even during transmission, the crystal filter 105 can be shared with reception without any problem by adjusting the gain of the high-frequency amplifier 103 to such an extent that weak power can be obtained. By making the transmission wave and the reception wave intermittent, the transmission / reception frequency can be made the same frequency. In this way, the configuration of the signal processing circuit of the high frequency module can be simplified and the power consumption can be reduced.
As described above, in the conventional high-frequency radio, the antenna filter cannot be used for both transmission and reception, so there are two antenna filters, but in any case, when the SAW filter 6 is used as the antenna filter. Has a wide bandwidth, so it also captures the image frequency. For this reason, an image suppression unit is indispensable for the signal processing circuit, the circuit configuration becomes complicated, and power consumption must be increased.

  The signal processing unit (# 1) includes a detection circuit 107 that performs detection by a direct detection method at the time of reception, a modulation circuit 108 that performs direct modulation at the time of transmission, a local oscillator that oscillates a high-frequency local signal to be supplied to the detection circuit 107 and the modulation circuit 108 109, an intermediate frequency amplifier 110 that amplifies the detected intermediate frequency, an analog / digital converter (ADC) 111 that converts the amplified intermediate frequency signal into a digital value and outputs the digital value to a digital output terminal T12, and a digital input terminal T13 A digital / analog converter (DAC) 112 that converts an input digital signal into an analog signal, and transmission / reception change-over switches 101, 104, and 106 for selectively switching the transmission direction of the signal are provided.

The crystal resonator oscillates a high-frequency local signal having a frequency difference (= 315 [MHz] −about 49 [kHz]: strictly 49.152 [kHz]) between the communication frequency and the intermediate frequency signal. . Preferably, a crystal piece having the same characteristics as the crystal piece used for the crystal filter 105 is employed as a constituent element. By using a frequency of about 49 [kHz], for example, in a signal processing circuit (for example, a modulation / demodulation circuit), processing for modulation / demodulation can be performed at a low clock frequency, so that power consumption can be reduced. There is a utility.
The transmission / reception change-over switches 101, 104, and 106 are controlled through a control circuit (not shown), and all open and close at the same timing. More specifically, one value of the binary signal is turned on, and the other value is turned off. For example, when the signal is on, the high-frequency amplifier and the signal processor are operated as a receiver. When the signal is off, these are used as a transmitter. Make it work. Therefore, the same (one) crystal filter can be used for both the transmitting antenna filter and the receiving antenna filter. The wireless module 100 is powered by the power supply 20 connected to the power supply terminal T14.

  The electronic circuit portions of the high frequency amplification unit and the signal processing unit can be configured by the RFIC chip (software radio) described above. In this RFIC chip, the operation timing of the signal processing of each part described above is a clock output from a clock oscillator (not shown) that outputs a clock signal of about 32 [kHz] (strictly 32.768 [kHz]). It can be about 65 [kilosamples / second] depending on the signal. Since the clock oscillator of about 32 [kHz] is currently mass-produced by the most popular oscillation circuit, it is inexpensive and can contribute to the cost reduction of the wireless module 100.

At the time of mounting, the RFIC chip, the crystal resonator included in the local oscillator 109, and the crystal filter 105 are bundled in a module container made of, for example, a multilayer ceramic as shown in FIG. In particular, the crystal resonator and the crystal filter 105 are mounted in a part that is an operating environment in which the temperature characteristics and the secular change characteristics of a crystal piece that is a main component are substantially the same. In addition, when the quartz pieces included in both have the same characteristics, for example, a material other than the quartz constituting the both, for example, the same material is used for the electrode and the adhesive member, the aging characteristics tend to be almost the same.
For this reason, even if the ambient temperature of the quartz filter 105 rises or the frequency shifts due to secular change, the frequency at the time of detection or modulation shifts in the same direction, so that these influences can be mitigated.

The radio module 100 configured as described above can transmit a carrier band signal modulated by this digital signal to a receiver as a communication partner by inputting the digital signal to be transmitted from the digital input terminal T13. It becomes like this. Since the transmission system amplifies and transmits after passing through the crystal filter 105, the input level of the crystal filter 105 may be small.
In addition, since the signal transmitted from the transmitter that is the communication partner appears at the digital output terminal T12, the received signal can be digitally processed. Thus, the wireless module 100 that has a simple structure, high versatility, and can be mass-produced can be realized.

<< Other embodiments >>
The high-frequency radio of the present invention can be implemented as an extension of the above-described radio module 100 for both transmission and reception to realize various radio communication systems. For example, the present invention can be implemented as a wireless module to which a signal processing unit (signal processing unit # 2) that realizes a specific wireless communication procedure according to the application is added.
FIG. 6 shows an example of the configuration of an IC chip for extending the wireless module 100 shown in FIG. 5 to realize short-range wireless communication using a spread spectrum (SS) method. As a premise, it is assumed that a spreading code (pseudo random signal) defined with a communication partner is held. Such an IC chip is also a kind of software / radio, which is referred to as a BB (Base Band) IC chip for convenience.

Here, before explaining the configuration of the BBIC chip 200, an outline of the SS method performed by the wireless module of this embodiment will be mentioned.
In the SS system, at the time of transmission, two-stage modulation is performed and data is transmitted.
In the primary modulation, a narrow band signal, that is, a signal having an arbitrary frequency within a band used for communication is obtained by using a BPSK (Binary Phase-Shift Keying) system that is resistant to noise. Next, an SS signal with an expanded frequency band is obtained by multiplying the spreading codes that are switched at high speed. This is because the signal that switches at high speed has a broad spectrum. This process is called “secondary modulation” or “spread modulation”.

  At the time of reception, secondary demodulation (spread demodulation) is first performed in order to restore the spread modulated data. That is, the received SS signal is multiplied by the same spreading code as that on the transmission side in a state synchronized with the transmission side. This process is called “despreading”. By performing this despreading, the original narrowband signal is obtained, so that the primary demodulation is finally performed to reproduce the data transmitted from the transmission side. That is, the signal is spread when the spread code is applied once to the narrowband signal, and is restored when the same code is applied again at the receiving side.

  If different code sequences are assigned to a plurality of communication partners, communication can be performed simultaneously and using the same frequency band without interfering with each other. The SS method is a wireless communication method performed in this way. However, if the spreading code is not synchronized between the transmitting side and the receiving side or is a code sequence with a small correlation, the original narrowband signal cannot be obtained, and the power is still low. Only spectral density signals can be obtained. The SS system is suitable for the short-range wireless communication system because there is an advantage that the communication quality deteriorates only gradually as the number of wireless devices that can be used simultaneously in the same frequency band is increased.

The BBIC chip 200 is configured, for example, as shown in FIG. 6 in order to realize the communication by the SS method.
That is, the reception system includes a carrier demodulation circuit 201 for demodulating a digital signal of 48 [kHz] input from the wireless module 100 through the digital input terminal T211, a despreading circuit 202 for performing the above-described secondary demodulation, The BPSK demodulating circuit 203 performs the primary demodulation of the narrowband signal obtained by the above and outputs the demodulated data to the control circuit 300 through the digital output terminal T213.

  The control circuit 300 is connected to a drive mechanism of an object, for example, a door opening / closing mechanism of a vehicle, and is driven and controlled by demodulated data.

  The transmission system includes a framer 207 that frames data input from the control circuit 300 through the data input terminal T214, for example, data representing a control notification, and a BPSK modulation circuit 206 that performs primary modulation of the frame signal obtained thereby. The spreading circuit 205 that performs secondary modulation using the spreading code assigned to itself, stored in the spreading code storage unit 209, corrects the frequency of the secondary modulated data and the carrier band signal at the time of transmission. A carrier error correction circuit 204 for sending instruction data for transmission to the wireless module 100 through the data output terminal 212, and a timing synchronization circuit 208 for synchronizing the timing of digital processing during transmission and reception.

The carrier error correction circuit 204 detects a difference (error) between the frequency of the signal component included in the received carrier band signal and the frequency of the high frequency local signal of the own device, and sets the frequency difference data representing the detected frequency difference to a predetermined value. The frequency difference data is read from the memory when the signal to be transmitted to the communication partner is carrier-modulated, and the frequency of the local high frequency signal is corrected based on the read frequency difference data. is there. Thereby, the frequency of the carrier band signal transmitted from the own device can be synchronized with the frequency of the received carrier band signal.
Since it is a digital process, the generation of this frequency difference data is a very simple process compared to the case of using analog data.

  The carrier error correction circuit 204 can be a very effective means when the transmission and reception sides communicate synchronously as in the SS system, but this circuit does not necessarily have to be held on both the transmission and reception sides. . When the BBIC chip 200 is used by being mounted on an SS type parent device, the carrier error correction circuit 204 is provided. When the BBIC chip 200 is mounted on a child device, the output of the diffusion circuit 205 is directly connected to the data output terminal T212. May be output. When installed in the slave unit, transmission may be performed intermittently in order to save power consumption.

The operation of each unit is performed by a control signal input from the control circuit 300 via the control terminal T215 in accordance with a 32 [kHz] clock signal oscillated from the clock oscillator 30 and input via the clock input terminal T216. A power supply 20 is connected to the power supply terminal T217.
Note that the signal processing unit (# 2) illustrated in FIG. 6 and the signal processing unit (# 1) illustrated in FIG. 5 may be integrated. In this case, one power source 20 and one clock oscillator 30 are sufficient.

  In the wireless module of the present invention having the signal processing unit shown in FIGS. 5 and 6 that performs short-distance communication under substantially the same conditions as the wireless module using the SAW filter, the frequency of the passing frequency can be reduced by using the crystal filter. Since the bandwidth is extremely narrow, for example, 20 [kHz], by using noise-resistant BPSK modulation and spread modulation, the reception sensitivity is improved to about 30 dB as compared with the case where the SAW filter is used. Furthermore, the number of channels (number of spreading codes to be assigned) that can be used simultaneously in the same frequency band without interference increases dramatically.

As described above, the features of the present invention have been described through a plurality of exemplary embodiments, the high-frequency radio of the present invention is not necessarily limited to use in a keyless entry control system, and all wireless communications using a short-range communication method, for example, It can be easily understood that the present invention can be widely applied to industrial tele-control devices, lighting controllers, construction traffic signals, garage openers, games, equipment security systems, residential security systems, and the like.
In addition, since the high-frequency wireless device of the present invention can be used in the same manner for other wireless communication systems that perform communication using frequencies in the VHF band or higher, the scope of the present invention is limited to the short-range communication system. Of course not.

The block diagram of the high frequency radio which showed one embodiment of the present invention. Sectional drawing which showed the state which stored the high frequency radio apparatus shown in FIG. 1 in the module container. BRIEF DESCRIPTION OF THE DRAWINGS It is structure explanatory drawing of the crystal filter used for the high frequency radio | wireless machine of this invention, The figure (a) is a top view, The figure (b) is the AA sectional drawing. The frequency-attenuation characteristic figure by a crystal filter. The block diagram of the high frequency radio which showed other embodiment of this invention. The block diagram of IC chip mounted in a high frequency radio | wireless machine, or operate | moving in cooperation with a high frequency radio | wireless machine. The chart figure which showed the usable range of a crystal filter and a SAW device. The block diagram of the receiver of the prior art example which performs near field communication. The frequency-attenuation characteristic figure by a SAW filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transmitter, 2 ... Receiver, 3 ... Crystal filter, 4 ... Reception mechanism, 5 ... Antenna, 6 ... SAW filter, 7 ... IC chip, 8 * .... Container body, 9 ... crystal piece, 10a, 10b ... input / output electrode, 11 ... common electrode, 12 ... extraction electrode, 13 ... conductive adhesive, 14 ... preamplifier , 15 ... Cover, 100 ... Wireless module, 101, 104, 106 ... Transmission / reception selector switch, 102 ... Low noise amplifier, 103 ... Power amplifier, 105 ... Crystal filter, 107 ..Detection circuit 108... Modulation circuit 109 109 local oscillator 110 intermediate frequency amplifier 111 analog / digital converter (ADC) 112 digital / analog converter DAC), 20 ... power supply ( S), 200 ... IC chip, 201 ... carrier demodulation circuit, 202 ... despreading circuit, 203 ... BPSK demodulation circuit, 204 ... carrier error correction circuit, 205 ... diffusion circuit, 206 BPSK modulation circuit 207 Framer 208 Timing synchronization circuit 209 Spread code storage unit 30 Clock oscillator 300 Control circuit

Claims (7)

A wireless module that performs short-range wireless communication using weak power, which is not subject to legal regulations, using a carrier band signal in the UHF band, and a processing unit that performs processing of a signal passed between the communication partner device through the wireless module. Have
The radio module filters the carrier band signal after high frequency amplification at the time of reception, and transmits and receives a crystal band filter for filtering the carrier band signal of the same frequency as the received carrier band signal before the high frequency amplification at the time of transmission, and for direct detection And a crystal resonator that oscillates a local signal for direct modulation,
The crystal filter operates in an environment where the direction of frequency deviation to be filtered is the same as the direction of frequency deviation at the time of detection or modulation by the local signal,
The processing means generates a signal that is directly modulated based on spread-modulated data obtained by spreading with a spreading code determined with a communication partner at the time of transmission, and a signal directly detected at the time of reception. The signal obtained by despreading the spreading code is demodulated.
High frequency radio. The carrier band signal is an intermittent signal;
The high frequency radio device according to claim 1.   The high-frequency radio apparatus according to claim 2, wherein the crystal filter filters the carrier band signal with a bandwidth of [kHz]. The crystal filter is housed in one module container that makes its temperature characteristics and aging characteristics substantially the same as the temperature characteristics and aging characteristics of the crystal resonator.
The high-frequency radio device according to claim 1, 2 or 3. The module container includes other components of the wireless module and the processing means.
The high frequency radio device according to claim 4. The processing means detects the difference between the frequency of the signal component contained in the received carrier band signal and the frequency of the local signal of the own device, records the frequency difference data representing the detected frequency difference in a predetermined memory, When modulating a signal to be transmitted to a communication partner, the frequency difference data is read from the memory, and based on the read frequency difference data, a correction circuit that corrects the frequency of the carrier band signal for transmission is included.
The high-frequency radio device according to any one of claims 1 to 5. The processing means is a software radio that operates in cooperation with a processor and software existing in a predetermined storage area, or whose processing operation is performed by a predetermined firmware. Can be changed
The high frequency radio device according to claim 6.

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