JP2011229042A - Communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a TDMA communication device having one DSP which has a technique capable of executing a loop back test.SOLUTION: A communication device comprises a DSP 1, a switch 10, a transmission circuit 41, a reception circuit 42, a reception detection unit 43, and a determination unit 44. The reception detection unit 43 detects the signal inputted from the transmission circuit 41 to the reception circuit 42 via the switch 10 and output from the reception circuit 42, to detect the level of the signal. The determination unit 44 determines abnormality on the basis of the result of comparison of the level detected by the reception detection unit 43 with a predetermined reference value.

Description

  The present invention relates to a communication apparatus that performs wireless communication by a TDMA (Time Division Multiple Access) method, and particularly relates to a communication apparatus having a loopback test function.

  2. Description of the Related Art Some communication apparatuses that perform wireless communication perform a loopback test to check whether there is an abnormality in the basic characteristics of a transmission circuit and a reception circuit by demodulating a signal input from the transmission circuit to the reception circuit. Patent Document 1 discloses a technique for performing a folding test.

JP-A-6-152461

  It has been proposed to apply such a loopback test to a communication apparatus that performs TDMA wireless communication in which a transmission period and a reception period repeatedly appear. In the TDMA wireless communication, the transmission slot and the reception slot are separated in time, and the receiving terminal such as a mobile station is required to reduce the size and cost of the terminal. A single DSP (Digital Signal Processor) is often used for the communication device. However, since a single DSP cannot perform modulation and demodulation at the same time, a TDMA communication device having a single DSP cannot perform a loopback test.

  Therefore, the present invention has been made in view of the above problems, and provides a technique capable of performing a loopback test in a TDMA communication apparatus having a modulation / demodulation unit such as one DSP. For the purpose.

  A communication apparatus according to the present invention is a communication apparatus that performs wireless communication by a TDMA (Time Division Multiple Access) method in which a transmission period and a reception period repeatedly appear, and a transmission unit that performs predetermined signal processing for transmission; A reception unit that performs predetermined signal processing for reception, and a modulation / demodulation unit that is connected to and shared by the transmission unit and the reception unit. Then, a switch that can connect the output of the transmission unit and the input of the reception unit, and a signal that is input from the transmission unit via the switch to the reception unit and output from the reception unit are detected to detect the level of the signal A first detector. And the determination part which determines abnormality based on the 1st comparison result of the detection level in a 1st detection part and a predetermined reference value is provided.

  According to the present invention, an abnormality can be detected by the determination unit even when the modulation / demodulation unit does not demodulate the signal during the loopback test. Therefore, the loopback test can be performed even if the number of modems, for example, DSPs is one.

It is a block diagram which shows the structure of a contrast object communication apparatus. 2 is a block diagram showing a configuration of a communication apparatus according to Embodiment 1. FIG. 3 is a flowchart showing an operation of the communication apparatus according to the first embodiment. 6 is a block diagram showing a configuration of a communication apparatus according to Embodiment 2. FIG. 6 is a flowchart showing an operation of the communication apparatus according to the second embodiment. 6 is a diagram illustrating an operation result of the communication apparatus according to Embodiment 2. FIG.

<Embodiment 1>
First, before describing a communication apparatus according to the present invention, a communication apparatus to be compared with the communication apparatus (hereinafter referred to as “comparison target communication apparatus”) will be described. FIG. 1 is a block diagram illustrating a configuration of a comparison target communication device. The comparison target communication device includes a D / A converter 2, an antenna switch 8, an antenna 9, a switch 10, an A / D converter 16, an attenuator 18 (attenuator), and a transmission circuit 41 indicated by a broken line. A receiving circuit 42 indicated by a broken line, a modulator 81, and a demodulator 82.

  This comparison target communication device has a TDMA (Time Division Multiple Access) in which a period for transmitting a transmission signal to a communication partner apparatus (transmission slot) and a period for receiving a reception signal from the communication partner apparatus (reception slot) are repeated. ) Method wireless communication. The comparison target communication apparatus passes the transmission circuit 41 from the modulation unit 81 and returns the signal that is turned back before the antenna 9 through the reception circuit 42 and demodulates the signal in the demodulation unit 82. It is possible to perform a loopback test for detecting an abnormality in the receiving circuit 42. Hereinafter, the configuration of such a comparison target communication device will be briefly described.

  The modulation unit 81 generates a digital signal by modulating a carrier wave based on data to be transmitted, and outputs the generated digital signal to the D / A converter 2. In the present embodiment, a digital signal is generated for each of the I component and the Q component. The D / A converter 2 converts the digital signal from the modulation unit 81 into an analog signal and outputs the analog signal to the transmission circuit 41.

  The transmission circuit 41 is a transmission unit that performs predetermined signal processing for transmission, and includes a quadrature modulator 3, a transmission IF amplifier 4, a mixer 5, a transmission local oscillator 6, and a transmission RF amplifier 7. . The transmission circuit 41 according to the present embodiment performs predetermined signal processing for transmission on the analog signal from the D / A converter 2 and sends the analog signal obtained thereby to the antenna switch 8 and the attenuator 18. Output.

  The reception circuit 42 is a reception unit that performs predetermined signal processing for reception, and includes a reception RF amplifier 11, a mixer 12, a reception local oscillator 13, a reception IF amplifier 14, and a bandpass filter 15. . The receiving circuit 42 according to the present embodiment performs predetermined signal processing for reception on the analog signal input thereto and outputs the analog signal obtained thereby to the A / D converter 16.

  The A / D converter 16 converts the analog signal from the receiving circuit 42 into a digital signal and outputs it to the demodulator 82. The demodulation unit 82 acquires data included in the digital signal by demodulating the digital signal from the A / D converter 16.

  The antenna switch 8 selectively connects either the transmission circuit 41 or the switch 10 to the antenna 9. The switch 10 selectively connects either the antenna switch 8 or the attenuator 18 to the reception RF amplifier 11. Since the attenuator 18 is connected to the transmission RF amplifier 7 of the transmission circuit 41, the switch 10 can substantially connect the output of the transmission circuit 41 and the input of the reception circuit 42.

  Next, an operation when the comparison target communication apparatus having the above configuration performs TDMA wireless communication with the communication partner apparatus will be described. In this case, the switch 10 continuously connects the antenna switch 8 and the reception RF amplifier 11. Then, the connection between the antenna 9 and the transmission circuit 41 and the connection between the antenna 9 and the switch 10 are alternately performed by the antenna switch 8. By connecting the antenna switch 8 and the switch 10 as described above, the connection between the antenna 9 and the transmission circuit 41 and the connection between the antenna 9 and the reception circuit 42 are repeatedly performed.

  When the transmission circuit 41 and the antenna 9 are connected, the transmission circuit 41 transmits a transmission signal to the communication partner apparatus via the antenna 9. On the other hand, when the receiving circuit 42 and the antenna 9 are connected, the receiving circuit 42 receives a reception signal from the communication partner apparatus via the antenna 9. Since the period in which the antenna 9 and the transmission circuit 41 are not connected and the period in which the antenna 9 and the reception circuit 42 are not connected are both very short, the comparison between the communication target device and the communication partner device is not possible. Bidirectional simultaneous communication can be simulated.

  Next, an operation when the comparison target communication device performs a loopback test will be described. In this case, the switch 10 continuously connects the attenuator 18 and the reception RF amplifier 11. Then, the frequency of the reception local oscillator 13 is switched so that the output signal of the transmission circuit 41 is converted into an intermediate frequency signal that can be used in the reception circuit 42.

  When the above operation is performed, the output signal of the transmission circuit 41 is input to the reception circuit 42 via the switch 10 with the amplitude attenuated by the attenuator 18. As a result, the signal input from the modulation unit 81 to the transmission circuit 41 via the D / A converter 2 and output from the transmission circuit is folded back, and the attenuator 18, the switch 10, the reception circuit 42, and the A / D. The signal is input to the demodulator 82 via the converter 16. In this case, since the return signal demodulated by the demodulator 82 changes depending on whether the transmission circuit 41 and the reception circuit 42 are abnormal, the return signal demodulated by the demodulator 82 in the comparison target communication device. Based on the above, abnormality of the transmission circuit 41 and the reception circuit 42 can be detected.

  Now, in order to perform a loopback test in the comparison target communication device, it is necessary to perform modulation and demodulation simultaneously. However, since one DSP (Digital Signal Processor) cannot perform modulation and demodulation at the same time, it is necessary to provide a DSP for each of the modulation and demodulation in the comparison target communication device. As a result, it has been difficult to reduce the size and cost of the comparison target communication device.

  Therefore, in this embodiment, the communication apparatus has one DSP, and even such a communication apparatus can perform a loopback test. Hereinafter, the configuration of the communication apparatus according to the present embodiment will be described in detail.

  FIG. 2 is a block diagram showing a configuration of the communication apparatus according to the present embodiment. In the following description of the communication device according to the present embodiment, parts that are the same as those in the comparison target communication device are denoted by the same reference numerals, and redundant description is omitted. In the configuration of the communication device according to the present embodiment, the modulation unit 81 and the demodulation unit 82 are replaced with the DSP 1 in the configuration of the comparative communication device, and the reception detection unit 43, the determination unit 44, and the frequency change unit 51 are added. It has become a thing.

  The DSP 1 is a modulation / demodulation unit that is connected to and shared by the transmission circuit 41 and the reception circuit 42. The DSP 1 functionally includes a modulation unit 21 that generates a digital signal by modulating a carrier wave based on data. By demodulating the input digital signal, it functionally has a demodulator 22 that acquires data contained therein. That is, the DSP 1 includes the same modulation unit 21 and demodulation unit 22 as the above-described modulation unit 81 and demodulation unit 82 as functional blocks. However, the modulator 21 and the demodulator 22 cannot operate simultaneously. In the communication apparatus according to the present embodiment, one DSP 1 having such a modulation unit 21 and a demodulation unit 22 is provided.

  The D / A converter 2 converts the digital signal from the modulation unit 21 of the DSP 1 into an analog signal and outputs the analog signal to the quadrature modulator 3. The A / D converter 16 converts the analog signal from the bandpass filter 15 into a digital signal and outputs the digital signal to the demodulator 22 of the DSP 1.

  Similar to the transmission circuit 41 of the comparison target communication device, the transmission circuit 41 according to the present embodiment includes each component from the quadrature modulator 3 to the transmission RF amplifier 7, and includes the components from the D / A converter 2. The output signal is subjected to predetermined signal processing for transmission, and the resulting signal is output to the antenna switch 8 and the attenuator 18. Hereinafter, each component of the transmission circuit 41 will be described.

  The quadrature modulator 3 performs quadrature modulation on the analog signals of the I component and Q component output from the D / A converter 2 to generate an intermediate frequency signal, and outputs the intermediate frequency signal to the transmission IF amplifier 4. The transmission IF amplifier 4 amplifies the intermediate frequency signal from the quadrature modulator 3 and outputs it to the mixer 5.

  The mixer 5 and the transmission local oscillator 6 function as a frequency conversion unit that converts the frequency of the intermediate frequency signal output from the transmission IF amplifier 4 into a higher frequency band (carrier band). Specifically, the mixer 5 multiplies the intermediate frequency signal from the transmission IF amplifier 4 by a signal from the transmission local oscillator 6 (hereinafter referred to as “transmission local oscillation signal”), and is obtained thereby. Output a signal. Then, a band-pass filter (not shown) performs a predetermined filtering process on the output signal from the mixer 5, thereby removing unnecessary signals from the output signal and taking out a signal having a carrier band. Then, the bandpass filter outputs the extracted signal to the transmission RF amplifier 7. The transmission RF amplifier 7 amplifies the output signal from the bandpass filter, and outputs the amplified output signal to the antenna switch 8 and the attenuator 18 as an output signal of the transmission circuit 41.

  Similarly to the reception circuit 42 of the comparison target communication device, the reception circuit 42 according to the present embodiment includes each component from the reception RF amplifier 11 to the bandpass filter 15, and a predetermined signal for reception is received as an input signal. The signal obtained thereby is output to the A / D converter 16. Hereinafter, each component of the receiving circuit 42 will be described.

  The reception RF amplifier 11 amplifies a signal input as an input signal of the reception circuit 42 and outputs the amplified signal to the mixer 12. The mixer 12 and the reception local oscillator 13 function as a frequency conversion unit that converts the frequency of the signal output from the reception RF amplifier 11 to a lower frequency band (intermediate frequency band). Specifically, the mixer 12 multiplies the output signal from the reception RF amplifier 11 by a signal from the reception local oscillator 13 (hereinafter referred to as “reception local oscillation signal”), and a signal obtained thereby. Is output to the reception IF amplifier 14.

  The reception IF amplifier 14 amplifies the output signal from the mixer 12 and outputs the amplified output signal to the bandpass filter 15. The band pass filter 15 performs a predetermined filtering process on the output signal from the reception IF amplifier 14, thereby removing unnecessary signals from the output signal and taking out an intermediate frequency signal. That is, the band pass filter 15 extracts a desired signal to be an intermediate frequency signal from the signal obtained by multiplication in the mixer 12. Then, the band pass filter 15 outputs the extracted intermediate frequency signal to the A / D converter 16 and the detection circuit 23.

  Next, the reception detection unit 43 will be described. The reception detection unit 43 is provided separately from the DSP 1 and detects a signal input from the transmission circuit 41 to the reception circuit 42 via the switch 10 and output from the reception circuit 42 to detect the level of the signal. To do. The reception detection unit 43 according to the present embodiment includes a detection circuit 23 and a level detection unit 24.

  The detection circuit 23 generates a DC voltage based on the signal from the bandpass filter 15 of the reception circuit 42 and outputs the DC voltage to the level detection unit 24. The level detection unit 24 detects the level of the signal from the DC voltage output from the detection circuit 23 and outputs the level to the determination unit 44.

  The determination unit 44 is provided separately from the DSP 1 and compares the detection level of the level detection unit 24, that is, the detection level of the reception detection unit 43 with a predetermined reference value, and the comparison result (hereinafter, “ The abnormality is determined on the basis of the “reception side comparison result”.

  The frequency changing unit 51 is activated when the loopback test is performed, and changes the frequency of at least one of the transmission local oscillation signal from the transmission local oscillator 6 and the reception local oscillation signal from the reception local oscillator 13. In the present embodiment, the frequency changing unit 51 is described as changing the frequency of the reception local oscillation signal. However, instead of changing the frequency of the reception local oscillation signal, the frequency of the transmission local oscillation signal may be changed. Then, the frequencies of both the reception local oscillation signal and the transmission local oscillation signal may be changed.

  Next, the operation of the communication apparatus according to the present embodiment configured as described above will be described. The operation when the communication apparatus according to the present embodiment performs TDMA wireless communication with the communication partner apparatus is the same as that of the comparison target communication apparatus, and thus the description of the operation is omitted.

  FIG. 3 is a flowchart showing an operation for performing a loopback test in the communication apparatus according to the present embodiment. Hereinafter, an operation in which the communication apparatus according to the present embodiment performs a loopback test will be described with reference to FIG. First, in step s1, the switch 10 is switched so that the connection between the antenna switch 8 and the reception RF amplifier 11 is disconnected and the connection between the attenuator 18 and the reception RF amplifier 11 is connected. It is done. In step s2, the frequency changing unit 51 controls the reception local oscillator 13 so as to convert the output signal of the transmission circuit 41 into an intermediate frequency signal that can be used in the reception circuit 42, and the frequency of the reception local oscillation signal. To change. In the present embodiment, the frequency changing unit 51 changes the frequency of the reception local oscillation signal so that the frequency of the transmission local oscillation signal of the transmission local oscillator 6 matches the frequency of the reception local oscillation signal of the reception local oscillator 13. change.

  In step s3, the reception detection unit 43 detects a signal input from the transmission circuit 41 to the reception circuit 42 via the switch 10 and output from the reception circuit 42, and detects the level of the detected signal. And the determination part 44 compares the detection level in the reception detection part 43, and a predetermined reference value, and determines abnormality based on the comparison result of the receiving side which is the comparison result. For example, if the detection level at the reception detection unit 43 is not within the reference range, the determination unit 44 proceeds to step s4, determines that at least one of the transmission circuit 41 and the reception circuit 42 is abnormal, and Notify the outside. On the other hand, when the detection level in the reception detection unit 43 is within the reference range, the determination unit 44 proceeds to step s5 and determines that the transmission circuit 41 and the reception circuit 42 are normal.

  In step s5, frequency changing unit 51 receives local oscillation so that the frequency of the transmission local oscillation signal and the frequency of the reception local oscillation signal coincide with each other so that the frequencies are close to each other. Change the frequency of the signal slightly. In the present embodiment, in Step 5, the frequency changing unit 51 changes the frequency of the received local oscillation signal so that the frequency of the received local oscillation signal is shifted by one channel from the frequency of the transmitted local oscillation signal.

  In step s6, the determination unit 44 detects a signal input from the transmission circuit 41 to the reception circuit 42 via the switch 10 and output from the reception circuit 42, and detects the level of the signal. Then, the determination unit 44 uses the detection level at the reception detection unit 43 when the frequency of the transmission local oscillation signal and the frequency of the reception local oscillation signal coincide with each other as the attenuation amount of the adjacent channel, and the frequency of the transmission local oscillation signal. And the ratio of the reception level in the reception detection unit 43 when the frequencies of the reception local oscillation signals are close to each other is obtained. That is, the determination unit 44 obtains a ratio between the detection level at step s3 and the detection level at step s6 as the attenuation amount of the adjacent channel. Then, the determination unit 44 determines the abnormality of the bandpass filter 15 based on the comparison result between the attenuation amount and a predetermined reference value.

  For example, if the attenuation characteristic of the bandpass filter 15 is good and the attenuation amount is within the reference range, the determination unit 44 proceeds to step s7 and determines that the bandpass filter 15 is normal. On the other hand, when the attenuation characteristic of the bandpass filter 15 deteriorates and the attenuation amount is not within the reference range, the determination unit 44 proceeds to step s8, determines that the bandpass filter 15 is abnormal, and accordingly. To the outside.

  According to the communication apparatus according to the present embodiment as described above, an abnormality can be detected by the determination unit 44 even when the DSP 1 does not demodulate the signal during the loopback test. Therefore, even if the number of DSPs 1 provided in the communication apparatus is one, the loopback test can be performed. Therefore, the communication device can be reduced in size.

  Moreover, according to the communication apparatus which concerns on this Embodiment, abnormality of the band pass filter 15 can also be detected by performing the substantially same operation | movement as a return | turnback test.

  In the present embodiment, the modulation / demodulation unit is described as being DSP1, but the present invention is not limited to this, and even when one device other than DSP1 that cannot perform modulation and demodulation is used at the same time, An effect can be obtained. In the present embodiment, the transmission unit (transmission circuit 41) includes components from the quadrature modulator 3 to the transmission RF amplifier 7, and the reception unit (reception circuit 42) includes a band from the reception RF amplifier 11. The components up to the pass filter 15 are provided. However, the present invention is not limited to this, and the D / A converter 2 may be included in the transmission unit, or the A / D converter 16 may be included in the reception unit. In this case, the reception detection unit 43 may detect the output signal from the A / D converter 16 instead of the output signal from the bandpass filter 15.

<Embodiment 2>
FIG. 4 is a block diagram showing a configuration of the communication apparatus according to the present embodiment. In the communication device according to the first embodiment, when there is an abnormality in the loopback test, it has not been possible to specify which of the transmission circuit 41 and the reception circuit 42 is abnormal. The communication device can identify the communication device. Hereinafter, the communication apparatus according to the present embodiment will be described. In the following description of the communication apparatus according to the present embodiment, parts that are the same as those of the communication apparatus according to Embodiment 1 are given the same reference numerals, and redundant descriptions are omitted.

  In the communication apparatus according to the present embodiment, a transmission detection unit 45 including a detection circuit 26 and a level detection unit 27 is added to the communication apparatus of the first embodiment. The detection circuit 26 generates a DC voltage based on the signal input from the transmission circuit 41 to the switch 10 and outputs the DC voltage to the level detection unit 27. The level detection unit 27 detects the level of the signal from the DC voltage output from the detection circuit 26 and outputs the level to the determination unit 44. Therefore, the transmission detector 45 detects the signal input from the transmission circuit 41 to the switch 10 and detects the level of the signal.

  The determination unit 44 compares the detection level of the level detection unit 27, that is, the detection level of the transmission detection unit 45 with a predetermined reference value, and the comparison result (hereinafter referred to as “transmission side comparison result”). Based on the reception side comparison result described in the first embodiment, it is determined which of the transmission circuit 41 and the reception circuit 42 is abnormal.

  Next, the operation of the communication apparatus according to the present embodiment configured as described above will be described. The operation when the communication apparatus according to the present embodiment performs TDMA wireless communication with the communication partner apparatus is the same as that of the comparison target communication apparatus, and thus the description of the operation is omitted.

  FIG. 5 is a flowchart showing an operation for performing a loopback test in the communication apparatus according to the present embodiment. Hereinafter, an operation in which the communication apparatus according to the present embodiment performs a loopback test will be described with reference to FIG. The flowchart shown in FIG. 5 is obtained by replacing step s4 with steps s11 to s13 in the flowchart shown in FIG. 3, and the other components are identical to each other. Therefore, in the following description, only steps s11 to s13 will be described.

  If the detection level at the reception detection unit 43 is not within the reference range in the reception side comparison result at step s3, the determination unit 44 proceeds to step s11, where the detection level at the transmission detection unit 45 and the predetermined reference value are Are compared, and it is determined which of the transmission circuit 41 and the reception circuit 42 is abnormal based on the comparison result of the transmission side as the comparison result. For example, when the detection level in the transmission detection unit 45 is within the reference range, the determination unit 44 proceeds to step s12, determines that the reception circuit 42 is abnormal, and displays that fact on the display unit. . On the other hand, if the detection level in the transmission detection unit 45 is not within the reference range, the determination unit 44 proceeds to step s13, determines that the transmission circuit 41 is abnormal, and displays that fact on the display unit. .

  FIG. 6 shows a table summarizing the operation results when the communication apparatus according to the present embodiment operates according to the flowchart shown in FIG.

  According to the communication device according to the present embodiment as described above, since it is possible to detect which of the transmission circuit 41 and the reception circuit 42 is abnormal, for example, when repairing the communication device, the abnormal part Identification becomes easy.

  In the flow shown in FIG. 5, when both the transmission circuit 41 and the reception circuit 42 are abnormal, the abnormality of the transmission circuit 41 is detected in step s13. Abnormality is not detected. Therefore, when the operation of step s13 is performed, it is desirable that the determination unit 44 performs step s3 again to detect whether the reception circuit 42 is abnormal.

  1 DSP, 5, 12 mixer, 10 switch, 15 band pass filter, 41 transmission circuit, 42 reception circuit, 43 reception detection unit, 44 determination unit, 45 transmission detection unit, 51 frequency change unit.

Claims (3)

A communication apparatus that performs wireless communication by a TDMA (Time Division Multiple Access) method in which a transmission period and a reception period repeatedly appear,
A transmitter that performs predetermined signal processing for transmission;
A receiver that performs predetermined signal processing for reception;
A modem that is connected to and shared by the transmitter and the receiver;
A switch capable of connecting the output of the transmitter and the input of the receiver;
A first detection unit that detects a signal input from the transmission unit to the reception unit via the switch and output from the reception unit, and detects a level of the signal;
A communication apparatus comprising: a determination unit that determines abnormality based on a first comparison result between a detection level in the first detection unit and a predetermined reference value. The communication device according to claim 1,
A second detector for detecting a signal input to the switch from the transmitter and detecting a level of the signal;
The determination unit
Based on the second comparison result between the detection level in the second detection unit and a predetermined reference value, and the first comparison result, it is determined which of the transmission unit and the reception unit is abnormal. Communication device. The communication device according to claim 1 or 2,
The transmitter is
A first mixer for multiplying a signal input to the transmission unit by a first signal;
The receiver is
A second mixer for multiplying a signal input to the receiving unit by a second signal;
A filter for extracting a desired signal from the signal multiplied by the second mixer,
A frequency changing unit that changes the frequency of at least one of the first and second signals so that the frequency of the first signal and the frequency of the second signal are close to each other;
The determination unit
When the detection level at the first detection unit when the frequency of the first signal and the frequency of the second signal coincide with each other, and the frequency of the first signal and the frequency of the second signal are close to each other A communication device that detects an abnormality of the filter based on a comparison result between a ratio of the detection level at the first detection unit and a predetermined reference value.

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