JP2005143127A - Frequency spectrum inversion computing method and program storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication apparatus capable of dealing with a communication system having a fixed duplex intervals, easily setting a transmit/receive frequency and realizing a duplex call between slave units in simple configuration and at a low cost. <P>SOLUTION: A receiving unit 20 receives signals of transmit frequencies fta, ftb from slave units A, B, and a signal processing part 40 inverts an entire frequency spectrum including a received signal frequency-converted by the receiving unit 20 . A transmitting part 30 converts the frequency of the received signal included in the frequency spectrum inverted by the signal processing part 40 and re-transmits the resultant signal as signals of receive frequencies fra, frb of the slave units A, B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a communication apparatus that frequency-converts and retransmits reception signals from a plurality of handset devices, and more particularly to a communication device as a wireless relay means for performing a call between handset devices such as cordless phones and mobile phones.

  Conventionally, as a communication device, in a cordless telephone that performs a call between slave units via a master unit, the processing of the high frequency part of the radio signal and the processing of the intermediate frequency are the same by using the adjacent channel for the call between the slave units. In this circuit, the received high-frequency signal is frequency-converted and retransmitted (see Japanese Patent Laid-Open No. 4-180415 (Patent Document 1)).

  As another communication apparatus, there is a communication apparatus that performs inter-slave communication using a simplex system that switches between transmission and reception according to time (see Japanese Patent Application Laid-Open No. 4-342346 (Patent Document 2)). This communication device switches the call direction by generating / receiving a (control) signal for switching between transmission and reception.

  Further, as another communication apparatus, there is a wireless communication apparatus capable of simultaneously communicating with a plurality of channels using a press talk wireless apparatus using a broadband wireless transmission / reception unit (Japanese Patent Laid-Open No. 11-196019). (See Patent Document 3)).

  By the way, the above communication apparatus has an advantage that the communication between the slave units can be performed only by using one radio unit, but there are the following problems (1) to (4).

  (1) Japanese Patent Laid-Open No. 4-180415 (Patent Document 1) “Communication apparatus for frequency-converting a received high-frequency signal and retransmitting it” synthesizes a 130 MHz signal with a 250 MHz band received signal. Since a transmission signal in the 380 MHz band is obtained, communication between slave units cannot be performed in a communication system with a constant duplex interval.

  Normally, a basic communication device having a plurality of radio units so that a call between slave units can be made, as shown in FIG. 9, a duplexer 151 to which an antenna 152 is connected, two sets of receiving units (123 to 128), and , A signal processing unit 140 that processes a signal from each receiving unit, two sets of transmission units (132 to 134) to which signals from the signal processing unit 140 are connected, two sets of local oscillation units 150, In a master unit as a communication device having a handset 160, a telephone line I / F 170, and a control / input / output unit 180, for example, when a duplex interval is constant at 130 MHz, one slave unit transmits at 254.1 MHz. Then, 384.1 MHz is received, and if the other handset transmits at 255.1 MHz, 385.1 MHz is received. Therefore, in order for two slave units to communicate with each other via the master unit, the master unit converts the transmission frequency 254.1 MHz of one slave unit into the reception frequency 385.1 MHz of the other slave unit, It is necessary to convert the transmission frequency 255.1 MHz of the slave unit to the reception frequency 384.1 MHz of one slave unit. However, in the means of the above publication, as shown in FIG. 10, 130 MHz is simply added to the signal received by the master unit. In a communication system with a constant duplex interval, (254.1 MHz becomes 384.1 MHz, There is a problem that it cannot be handled (because it is returned to the slave unit itself).

  (2) Japanese Patent Application Laid-Open No. 4-180415 discloses a communication apparatus that performs processing of a high-frequency portion of a radio signal and processing of an intermediate frequency in the same circuit by using adjacent channels for inter-slave communication. Since a channel is used, it is necessary to prepare an adjacent free channel at the start of a call, and there is a problem that a frequency cannot be arbitrarily selected. In addition, since this communication device employs a method of demodulating and modulating each channel, a circuit for handling each signal separately from a portion where signal processing is required is required, and the configuration is complicated and expensive. There is.

  (3) Since the “communication device that realizes the inter-slave communication using the simplex method for switching between transmission and reception according to time” disclosed in Japanese Patent Application Laid-Open No. 4-342346 (Patent Document 2), simultaneous transmission is not possible. For users who are accustomed to the method, there is a problem in that the call is uncomfortable, and for example, even if the other party wants to say something while speaking, the voice is not transmitted to the other party.

(4) Japanese Patent Application Laid-Open No. 11-196019 (Patent Document 3) also discloses a “communication apparatus having a radio configuration capable of simultaneously communicating with a plurality of channels using a press-talk type radio using a wide-band radio transceiver”. Similar to 3), there is a problem that duplex communication between the slave units is not possible.
JP-A-4-180415 JP-A-4-342346 JP-A-11-196019

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a communication device capable of supporting a communication system with a simple configuration and low cost, having a fixed duplex interval, easily setting a transmission / reception frequency, and realizing duplex communication between slave units. Is to provide.

  In order to achieve the above object, the frequency spectrum inversion calculation method of the present invention samples a signal at a predetermined sampling frequency, converts the sampling rate by complementing the sample data obtained by the sampling, Of the frequency spectrum after conversion, the spectrum of the signal that has been inverted due to the sampling is extracted by a band-pass filter.

  According to the frequency spectrum inversion calculation method, frequency spectrum inversion can be realized by digital signal processing.

  Also, the frequency spectrum inversion calculation method of the present invention samples a signal at a predetermined sampling frequency, thins out sample data obtained by the sampling, converts the sampling rate, and generates a frequency spectrum generated by the conversion of the sampling rate. The spectrum of the inverted signal is extracted by a band pass filter.

  According to the frequency spectrum inversion calculation method, the frequency spectrum inversion can be realized by digital signal processing, and the sampling rate can be lowered by thinning out the sample data obtained by the sampling in the sampling rate conversion. Can be reduced.

  Further, the frequency spectrum inversion calculation method of the present invention samples a signal at a predetermined sampling frequency, sets a part of the sample data obtained by the sampling to zero, and a part of the sample data obtained by the sampling. It is characterized in that the spectrum of the signal that has been inverted in frequency spectrum caused by setting the signal to zero is extracted by a band-pass filter or a low-pass filter.

  According to the frequency spectrum inversion calculation method, frequency spectrum inversion can be realized by digital signal processing, and since the sampling rate is not changed, signal processing can be performed with the same clock.

  A program storage medium according to the present invention stores a program for executing the frequency spectrum inversion calculation method described in any one of the above.

  According to the program storage medium of the above-described embodiment, for example, a signal processing unit program using a general-purpose DSP (Digital Signal Processor) is read from the program storage medium, thereby increasing the degree of freedom of signal processing.

  As is clear from the above, according to the frequency spectrum inversion calculation method of the present invention, the signal is sampled at a predetermined sampling frequency, the sampling data obtained by the sampling is complemented, the sampling rate is converted, and the post-conversion The frequency spectrum inversion can be realized by digital signal processing by taking out the spectrum of the frequency spectrum inverted signal generated by the above sampling from the frequency spectrum by using a band pass filter.

  In addition, since the sampling rate can be lowered by thinning out the sample data obtained by the sampling in the sampling rate conversion, the power consumption can be reduced.

  Further, according to the frequency spectrum inversion calculation method of the present invention, a signal is sampled at a predetermined sampling frequency, a part of sample data obtained by the sampling is set to zero, and a part of the sample data is set to zero. The frequency spectrum inversion can be realized by digital signal processing by extracting only the spectrum of the signal whose frequency spectrum is inverted by the band-pass filter or low-pass filter, and the sampling rate is not changed. It can be processed.

  Further, according to the program storage medium storing the program for executing the frequency spectrum inversion calculation method of the present invention, for example, by reading the program in the DSP of the signal processing unit created as a general-purpose component from the program storage medium, When a slave unit is newly added to a single communication device (communication between slave units is not required), the program of the program storage medium is set and changed so that communication between slave units is possible Can do. It is also possible to change the communication system so that it corresponds to a communication system having a different frequency or modulation method.

  The frequency spectrum inversion calculation method and program storage medium of the present invention will be described below in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 shows a conceptual diagram of a call between slave units in a cordless telephone having a master unit and a plurality of slave units as a communication device using the frequency spectrum inversion calculation method of the first embodiment of the present invention. In FIG. 1, A and B are slave units, 10 is a master unit, 20 is a receiver unit of the master unit 10, 30 is a transmitter unit of the master unit 10, and 40 is a signal as a full spectrum inversion unit of the master unit 10. It is a processing unit.

  In order to make a call between the slave unit A and the slave unit B, it is sufficient that the slave unit A and the slave unit B can transmit and receive the frequencies corresponding to each other. Since the machine is composed of a transmitter (not shown) that can handle the vicinity of the frequency ft and a receiver (not shown) that can handle the vicinity of the frequency fr, for example, the slave B transmits at the reception frequency fr of the slave A. If a signal is transmitted and received at the transmission frequency ft of the slave unit A, the slave unit A and the slave unit B can communicate directly. However, such a configuration is complicated and expensive. Since it is not realistic, the handset is not configured so as to transmit and receive mutually corresponding frequencies, and a communication between handset devices is usually performed via the base device.

  For this reason, as shown in FIG. 9, the conventional master unit has two sets of transmitters and receivers, respectively, to perform a call between slave units. Instead of preparing two sets of transmitters and receivers, two signals (signals from slave unit A and slave unit B) can be transmitted and received at the same time by one set of transmitters and receivers. In the case of receiving and transmitting on the network, it is not suitable for a communication system with a fixed duplex interval.

  Therefore, in the first embodiment, the entire spectrum inversion unit is provided between reception and transmission, and the transmission frequency fta as the first frequency of the slave unit A becomes frb as the third frequency in the master unit, and at the same time, The transmission frequency ftb as the second frequency of the machine B is set to be fr as the fourth frequency in the parent machine. As a result, communication between the slave units is realized in a communication system with a constant duplex interval.

  FIG. 2 is a configuration diagram of the base unit 10, and FIG. 3 is a schematic diagram of a signal frequency spectrum and a signal waveform. Hereinafter, the signal processing of the base unit 10 will be described in detail with reference to FIGS. In FIG. 3, the frequency spectrum in which a plurality of received waves are combined is schematically shown as a triangle so that the inversion of the frequency spectrum can be seen. As will be described later, the frequency spectrum indicated by this triangle is, for example, the four frequency components shown in FIG. 5 (b) combined and represented as shown in FIG. 5 (a).

  In the base unit 10, as shown in FIG. 2, the antenna 52 is connected to the duplexer 51, and the reception side output of the duplexer 51 is input to the RF (radio frequency) amplification unit 23. The output of the RF amplifier 23 is input to the frequency converter 25 via a BPF (band pass filter) 24. The output of the frequency converter 25 is input to an IF (intermediate frequency) amplifier 27 via the BPF 26. The output of the IF amplifier 27 is input to the A / D converter 41, and the output of the A / D converter 41 is input to the filter 47. The output of the filter 47 is input to the sampling rate conversion unit 42, and the output of the sampling rate conversion unit 42 is input to the filter 43. The output of the filter 43 is input to the D / A converter 44, the output of the D / A converter 44 is input to the frequency converter 32 via the BPF 31, and the output of the frequency converter 32 is RF amplified via the BPF 33. The output of the RF amplifier 34 is input to the transmission side of the duplexer 51.

  The RF amplifier 23, BPF 24, frequency converter 25, BPF 26 and IF amplifier 27 constitute the receiver 20, and the BPF 31, frequency converter 32, BPF 23 and RF amplifier 34 constitute the transmitter 30. The receiving unit 20 is composed of a broadband circuit capable of receiving signals in the transmission frequency bands of the slave units A and B, and the transmitting unit 30 is a broadband circuit capable of transmitting signals in the reception frequency band of the slave units A and B. It is configured.

  The A / D converter 41, the filter 47, the sampling rate conversion unit 42, the filter 43, and the D / A converter 44 constitute a signal processing unit 40. A local oscillation signal is supplied to the frequency conversion units 25 and 32 from the local oscillation unit 50 that receives the frequency setting signal from the signal processing unit 40. The signal processing unit 40 is connected to a handset 60, a telephone line I / F 70, and a control / input / output 80.

  In the base unit 10 of the communication apparatus having the above configuration, for example, a radio wave (254 MHz) transmitted from the slave unit A is received by the antenna 52 and input to the receiving unit 20 by the duplexer 51. In the receiver 20, the signal passes through the RF amplifier 23 and the BPF 24 and is input to the frequency converter 25. On the other hand, the local oscillator 50 generates a local oscillation signal of 250 MHz based on an instruction from the signal processing unit 40 and inputs the local oscillation signal to the frequency converter 25. An intermediate frequency signal is generated from these two signals, and only a 4 MHz signal passes through the BPF 26. Since the intermediate frequency signal output from the BPF 26 has a local oscillation frequency lower than that of the signal wave, the frequency spectrum of the received signal is not inverted. The intermediate frequency signal is amplified by the IF amplification unit 27 and input to the signal processing unit 40.

  Next, in the signal processing unit 40, the input intermediate frequency signal (shown in FIG. 3A) is sampled by an A / D (analog / digital) converter 41 at a sampling frequency fs = 19 Ms / s [sample / second]. To sample and A / D convert. FIG. 3B shows an A / D converted signal. This signal has an intermediate frequency signal at a position of 4 MHz, and a frequency spectrum at a position of 15 MHz (= 19 MHz-4 MHz) as a folded component. An inverted reception signal is generated.

  Next, the sampling rate conversion unit 42 sets the sampling frequency to 38 MHz and interpolates (interpolates) a value of 0 between each sample data. FIG. 3C shows a signal that has been subjected to sampling rate conversion. As shown in FIG. 3C, since the signal waveform after the sampling rate conversion is not changed from the signal waveform before the conversion, the frequency spectrum does not change.

  Next, the digital filter 43 passes the 15 MHz signal while attenuating the 4 MHz signal. As a result, the intermediate frequency signal whose frequency spectrum is inverted at 15 MHz is selected. FIG. 3D shows the output signal of the digital filter 43.

  Next, this is converted into an analog signal by a D / A (digital / analog) converter 44 and output to the transmitter 30.

  In the transmission unit 30, a signal of 15 MHz is passed by the BPF 31, and the aliasing component such as 23 MHz is attenuated. FIG. 3 (e) shows the output signal of the BPF 31. Next, the signal is mixed with the local oscillation frequency 365 MHz by the frequency conversion unit 32, and the frequency-converted 380 MHz signal is passed through the BPF 33, and then amplified to a predetermined signal strength by the RF amplification unit 34. A signal is transmitted to the caller's slave unit B via.

  As described above, the signal whose frequency spectrum is inverted by the signal processing unit 40 can be transmitted.

  Next, the signal frequency control will be described. Note that the transmission frequency as the first frequency of the child device A (first reception signal received by the parent device 10) is fta, and the reception frequency as the fourth frequency of the child device A (first transmission signal transmitted by the parent device 10). The frequency is set to fr, the transmission frequency as the second frequency of the slave unit B (second received signal received by the master unit 10) is ftb, and the third frequency of the slave unit B (second transmission signal transmitted by the master unit 10). The reception frequency is assumed to be frb. The transmission frequencies fta and ftb and the reception frequencies fra and frb are designated by the parent device 10 in the one-to-one communication between the parent device 10 and the child device A (or B). / The input / output 80 is a known value.

First, when the control / input / output unit 80 receives a request for communication between slave units from the slave unit A, the control / input / output unit 80 sets the local oscillation frequency fro for reception as follows:
fro = (fta + ftb) / 2-4 [MHz]
Is calculated and transmitted to the signal processor 40 and set in the local oscillator 50.

  Therefore, the converted intermediate frequency signal is arranged at a symmetrical position on both sides of the frequency of the slave unit A and the frequency of the slave unit B around 4 MHz. If the transmission frequency fta of the slave unit A and the transmission frequency ftb of the slave unit B are not limited, the local oscillation frequency fro for reception can take a value half of the channel interval, so that the synthesizer constituting the local oscillation circuit Since the comparison frequency becomes low, it is desirable to specify first so that (fta−ftb) is at least twice the channel interval.

  Next, the 15 MHz transmission intermediate frequency signal processed by the signal processing unit 40 is arranged at a symmetrical position on both sides with the frequency of the slave unit B and the frequency of the slave unit A centered on 15 MHz. The frequency spectrum is inverted as described above.

The local oscillation frequency fto for transmission is
fto = (fra + frb) / 2-15 [MHz]
Specify by.

The transmission / reception interval fdup is
fdup = fra-fta
= Frb-ftb
It becomes. That is, the transmission / reception frequency interval of the slave unit A and the transmission / reception frequency interval of the slave unit B are equal and constant.

When the frequency change of the transmission frequency fta of the handset A is sequentially calculated using the above, the receiving-side intermediate frequency fia frequency-converted by the frequency converter 25 is
fia = fta-fro
= Fta-((fta + ftb) / 2-4)
= 4+ (fta-ftb) / 2
The intermediate frequency fja after the frequency spectrum inversion is
fja = 19−fia
= 19- (4+ (fta-ftb) / 2)
= 15- (fta-ftb) / 2
It becomes.

  Therefore, the frequency fja is frequency spectrum inversion of fia.

Further, the transmission frequency subjected to frequency conversion by the frequency conversion unit 32 is:
fja + fto = 15- (fta-ftb) / 2 + (fra + frb) / 2-15
= (-Fta + ftb + fra + frb) / 2
= ((Fra-fta) + (ftb + frb)) / 2
= (Fdup + (frb−fdup + frb)) / 2
= Frb
It becomes.

  In this way, the transmission frequency fta of the child device A is converted to the reception frequency frb of the child device B, and the transmission signal of the child device A is received by the child device B.

Similarly, the intermediate frequency fib on the receiving side subjected to frequency conversion by the frequency conversion unit 25 is
fib = 4 + (ftb−fta) / 2
The intermediate frequency fjb after the frequency spectrum inversion is
fjb = 15- (ftb-fta) / 2
The transmission frequency subjected to frequency conversion by the frequency conversion unit 32 is
fjb + fto = fra
Thus, the transmission frequency ftb of the child device B is converted into the reception frequency fr of the child device A, and the transmission signal of the child device B is received by the child device A.

  Therefore, only in the case of communication between slave units, the duplex unit has a simple configuration, low cost, and a duplex interval without specially changing the transmission / reception frequency of the slave units or providing multiple sets of transmission units and reception units. It is possible to cope with a certain communication system, to easily set a transmission / reception frequency, and to realize duplex communication between slave units.

  Since the filter 43 for attenuating frequency components other than the received signal component included in the frequency spectrum inverted by the signal processing unit 40 as the entire spectrum inversion unit is provided, it is possible to suppress unnecessary retransmission of the frequency spectrum, Communication quality can be improved without interfering with other communications.

  In the signal processing unit 40, the intermediate frequency signal obtained by frequency conversion of the received signal is sampled by the A / D converter 41 at a predetermined sampling frequency, and the sample data obtained by the sampling is complemented by the sampling rate conversion unit 42. To change the sampling rate. Next, the frequency spectrum inversion is performed by using the frequency spectrum inversion calculation method in which only the spectrum of the frequency spectrum inversion signal generated by sampling out of the frequency spectrum after the sampling rate conversion is taken out by the filter 43 that passes the band. Can be realized by digital signal processing.

  In the first embodiment, the local oscillation frequency on the receiving side is set to 250 MHz, and the frequency spectrum is not inverted by the intermediate frequency signal. However, the local oscillation frequency on the receiving side is set to 258 MHz, and the frequency is set at the intermediate frequency stage. It is also possible to invert the spectrum (all spectrum inversion) so that the signal processor does not invert the frequency spectrum.

(Second Embodiment)
Further, by using analog signal arithmetic elements described in Japanese Patent Application Laid-Open Nos. 6-162230 and 6-168349 filed by the present applicant, signal processing can be performed without using an A / D conversion circuit. The part can also be realized.

  FIG. 4 shows the configuration of a master unit to which the analog signal arithmetic element is applied. In this parent device, since the frequency spectrum has already been inverted (all spectrum inversion) at the receiving unit as described above, the frequency spectrum has been inverted at the receiving unit, so there is no need for frequency spectrum inversion at the signal processing unit.

  In the master unit, as shown in FIG. 4, the antenna 52 is connected to the duplexer 51, and the reception side output of the duplexer 51 is input to the RF amplification unit 23. The output of the RF amplifier 23 is input to the frequency converter 25 via the BPF 24. The output of the frequency converter 25 is input to the IF amplifier 27 via the BPF 26. The output of the IF amplifier 27 is input to a filter 91 composed of an analog signal arithmetic element, and the output of the filter 91 is input to a filter 92 composed of an analog signal arithmetic element. The output of the filter 92 is input to the frequency conversion unit 32 via the BPF 31, the output of the frequency conversion unit 32 is input to the RF amplification unit 34 via the BPF 33, and the output of the RF amplification unit 34 is transmitted to the transmission side of the duplexer 51. Is entered.

  The RF amplifier 23, BPF 24, frequency converter 25, BPF 26 and IF amplifier 27 constitute a receiver, and the BPF 31, frequency converter 32, BPF 23 and RF amplifier 34 constitute a transmitter. The filters 91 and 92 constitute a signal processing unit 90. A local oscillation signal is supplied to the frequency conversion units 25 and 32 from the local oscillation unit 50 that receives the frequency setting signal from the signal processing unit 40. The signal processing unit 40 is connected to a handset 60, a telephone line I / F 70, and a control / input / output 80.

  In the base unit configured as described above, the received signal is filtered by the BPF 26, but the BPF 26 passes through a plurality of channels in order to make a call between the slave units. Since there is a possibility that an unnecessary signal (a signal transmitted from another slave unit) may be included in the passed signal, the signal is removed and retransmitted. This prevents the interference wave from being retransmitted to other slave units. There is a filter 91 for this purpose. The filter 91 is configured to pass only the frequency spectrum of the slave unit A and the slave unit B that are talking.

  5A to 5D show signal waveforms of signal processing of the master unit. FIG. 5 (a) shows the frequency spectrum of the input signal shown in FIG. 3 (a), which is composed of the components shown in FIG. 5 (b) as described in FIG. The filter 91 of the signal processing unit 90 is designed to pass the frequency A corresponding to the desired slave unit A and the frequency B corresponding to the slave unit B, as shown in FIG. At the output of the filter 91, unnecessary frequency spectrums X and Y are attenuated as shown in FIG. Therefore, even if this is retransmitted, no disturbing wave is generated.

  As shown in FIG. 6, the filter 91 can be realized by putting inputs into individual filters 101 and 102 and adding the outputs of the filters 101 and 102 with an adder 103.

  In this way, by configuring the entire spectrum inversion unit with the frequency conversion unit 25 of the reception unit 20 as a frequency conversion unit, the circuit configuration can be simplified and the circuit scale can be reduced.

  In the second embodiment, the frequency spectrum is inverted at the intermediate frequency stage of the frequency conversion unit of the reception unit. However, the frequency spectrum can be inverted by the frequency conversion unit of the transmission unit. In other words, the local oscillation frequency of the receiving unit is set to 250 MHz, and the frequency spectrum inversion is performed by setting the local oscillation frequency of the transmitting unit to 384 MHz without performing the frequency spectrum inversion in the receiving unit and the signal processing unit.

(Third embodiment)
In the first and second embodiments, it is possible to perform inter-slave communication in a modulation method (frequency modulation, amplitude modulation, etc.) that does not depend on frequency spectrum inversion. For example, as in a modulation method such as phase modulation, When the frequency spectrum is inverted, the phase change is reversed, and there are some that cannot be demodulated normally. In order to cope with this, the third embodiment solves the problem by changing the frequency spectrum of each signal wave (received signal) in the same direction as the received wave.

  FIG. 7 shows a main part of a base unit as a communication apparatus according to the third embodiment of the present invention.

  In the third embodiment, the output of the filter for each signal wave of the second embodiment (filters 101 and 102 shown in FIG. 6) is frequency spectrum inverted by the partial spectrum inversion units 105 and 106, respectively, and the frequency spectrum is inverted. The added signals are added by the adder 103 to invert the sidebands of the received signals and return to the original state as a whole. At this time, since frequency conversion is performed along with the frequency spectrum inversion, for example, the frequency of the local oscillator of the transmission unit is changed to cope with it.

  The partial spectrum inversion units 105 and 106 perform signal processing similar to that of the signal processing unit 40 of the first embodiment shown in FIG.

  As described above, since the partial spectrum inversion units 105 and 106 are provided, even if the modulation method is such that the inversion of the sideband of the input received signal is restored and the frequency spectrum inversion such as phase modulation has an effect, Inter-machine communication is possible.

(Fourth embodiment)
8A to 8D show a frequency spectrum inversion calculation method according to the fourth embodiment of the present invention. The input signal spectrum is in the vicinity of 15 MHz and is indicated by a triangular symbol (FIG. 8 (a)). When this input signal is sampled at 38 MHz, a spectrum is generated at a position of 23 MHz (= 38-15) (FIG. 8B).

  Next, every other sampling data is thinned out, so that the sampling frequency is halved to 19 MHz. As a result, a spectrum is generated at 4 MHz (= 19-15) as shown in FIG. Thereafter, D / A conversion is performed, and a band pass filter or a low pass filter that passes a frequency around 4 MHz is applied to extract the signal of FIG. This signal is a signal obtained by inverting the signal spectrum of FIG.

  In the above frequency spectrum inversion calculation method, the frequency spectrum inversion can be realized by digital signal processing, and the sampling rate can be lowered by thinning out the sample data obtained by sampling in the sampling rate conversion, thereby reducing the power consumption. Can do.

(Fifth embodiment)
Further, as a frequency spectrum inversion calculation method of the fifth embodiment of the present invention, after sampling the input signal shown in FIG. 8A of the fourth embodiment at a sampling frequency of 38 MHz, every other data is set to 0. Then, the frequency spectrum similar to that shown in FIG. 8C is generated with the sampling frequency kept at 38 MHz (FIG. 8E). Then, the signal shown in FIG. 8E is subjected to a band-pass filter or a low-pass filter that passes a frequency around 4 MHz, and the signal shown in FIG. 8F is extracted.

  In the frequency spectrum inversion calculation method, frequency spectrum inversion can be realized by digital signal processing, and since the sampling rate is not changed, signal processing can be performed with the same clock. Moreover, it becomes difficult to receive the aperture effect. Oversampling enables processing with a gentle filter characteristic.

  In the first to fifth embodiments, the cordless telephone has been described as a communication device that performs wireless communication. However, the communication device is not limited to this, and a communication device that performs frequency conversion and retransmits reception signals from a plurality of slave units. The present invention may be applied to. In addition, the present invention may be applied to a communication apparatus that performs frequency conversion and re-transmission of received signals from a plurality of slave units in a wired communication system.

  In the first to fifth embodiments, the master unit as the communication device has been described. However, a part or all of the program for executing the frequency spectrum inversion calculation method according to the present invention may be a floppy disk, an IC card, an IC itself, or the like. For example, a DSP (Digital Signal Processor) constituting the signal processing unit of the communication apparatus may be read and executed as necessary.

  Further, if all signal processing of the entire spectrum inversion unit and the partial spectrum inversion unit is calculated by a signal processing operation unit such as a DSP, the signal processing operation unit can be used as a general-purpose component without depending on the frequency allocation of the communication system. It can be manufactured and the mass production effect is enhanced. In this case, by arranging the partial spectrum inversion unit before the entire spectrum inversion unit, the filter operation performed at the beginning of the partial spectrum inversion unit can be performed at a low sampling frequency, so that power consumption can be reduced.

FIG. 1 shows a conceptual diagram of a call between slave units in a cordless telephone having a master unit and a plurality of slave units as a communication apparatus according to the first embodiment of the present invention. FIG. 2 is a configuration diagram of the master unit of the communication apparatus. FIG. 3 is a schematic diagram of a signal frequency spectrum and a signal waveform. FIG. 4 is a block diagram showing a master unit as a communication apparatus according to the second embodiment of the present invention. FIG. 5 is a diagram showing signal waveforms of signal processing of the master unit. FIG. 6 is a block diagram of the filter of the signal processing unit of the master unit. FIG. 7 shows a main part of a base unit as a communication apparatus according to the third embodiment of the present invention. FIG. 8 shows a frequency spectrum inversion calculation method according to the fourth embodiment of the present invention. FIG. 9 is a configuration diagram of a base unit as a conventional communication apparatus. FIG. 10 shows a conceptual diagram of a call between slave units in a cordless telephone having a master unit and a plurality of slave units as a conventional communication apparatus.

Explanation of symbols

A, B ... handset,
10 ... Master unit,
20 ... receiving part,
23, 34 ... RF amplification section,
24, 26, 31, 33 ... BPF,
25, 32 ... frequency conversion unit,
27 ... IF amplification unit,
30: Transmitter,
40, 90 ... signal processing unit,
41 ... A / D converter,
42 ... Sampling rate converter,
43, 47, 91, 92 ... filters,
44 ... D / A converter,
51. Duplexer,
52 ... Antenna,
60 ... handset,
70 ... Telephone line I / F,
80 ... Control / input / output,
101,102 ... filter,
103 ... adder,
105, 106... Partial spectrum inversion unit.

Claims (4)

Sample the signal at a given sampling frequency,
Complementing the sample data obtained by the above sampling to convert the sampling rate,
A frequency spectrum inversion calculation method, wherein a spectrum of the signal that has undergone frequency spectrum inversion resulting from the sampling out of the frequency spectrum after conversion of the sampling rate is extracted by a band-pass filter. Sample the signal at a given sampling frequency,
The sampling rate is converted by thinning out the sample data obtained by the above sampling,
A frequency spectrum inversion calculation method, characterized in that a spectrum of the signal that has undergone frequency spectrum inversion caused by the conversion of the sampling rate is extracted by a band-pass filter. Sample the signal at a given sampling frequency,
A part of the sample data obtained by the above sampling is set to zero,
Frequency spectrum inversion operation characterized in that the spectrum of the signal that has undergone frequency spectrum inversion caused by setting part of the sample data obtained by sampling to zero is extracted by a band pass filter or a low pass filter. Method.   A program storage medium storing a program for executing the frequency spectrum inversion method according to any one of claims 1 to 3.

Images