Receiving device and receiving method

Abstract

The present invention provides a receiving device and a receiving method that can obtain an appropriate RSSI value corresponding to the signal quality of the actual received signal received by the antenna. [Solution] The receiving device and receiving method include an RSSI detection unit 13 in the receiving high-frequency unit 10 that detects a detected RSSI value from the input received signal, a signal quality level calculation unit 23 in the receiving control unit 20 that calculates the signal quality level from the received signal digitally demodulated by the digital demodulation unit 21, a virtual RSSI conversion unit 24 that converts it into a virtual RSSI value corresponding to the signal quality of the actual received signal received by the antenna, and an RSSI output display unit 25 that displays the virtual RSSI value and the detected RSSI value.

Description

Technical Field

[0005] ,

[0001] The present invention relates to a receiving apparatus for receiving a digitally modulated radio signal, and more particularly to a receiving apparatus and a receiving method for providing an assumed RSSI (Received Signal Strength Indicator) value when receiving with an antenna based on the signal quality level of the received signal.

Background Art

[0002] <000,0009>[Conventional Technology] As a conventional wireless apparatus for receiving a digitally modulated radio signal, there is a wireless relay transmission apparatus (FPU: Field Pickup Unit) for television broadcasting. The FPU transmits video and audio from the shooting site to the receiving base station. [[ID=I8]]Specifically, it transmits video and audio data from outside the broadcasting station directly or indirectly to the broadcasting station (studio), processes the data received at the studio, and broadcasts it as a program, and is used for relay of news and sports events.

[0003] [Conventional FPU Receiving Base Station System: Figure 4] Next, a conventional FPU receiving base station system will be described with reference to FIG. 4. FIG. 4 is a schematic configuration diagram of a conventional FPU receiving base station system. As shown in FIG. 4, the conventional FPU receiving base station system includes a receiving high-frequency unit 1, a receiving control unit 2, an antenna 3, a rotating pedestal 4, a low-noise amplifier (LNA: Low Noise Amplifier) 5, and a frequency band filter (BPF: Band Pass Filter) 6.

[0004] The antenna 3 is attached to the rotating pedestal 4 and integrated, and the rotating pedestal 4 controls the direction of the antenna 3. Also, the LNA 5 and the BPF 6 are provided on the rotating pedestal 4. Then, the antenna 3, the rotating pedestal 4, the LNA 5, and the BPF 6 constitute the FPU receiving base station.

[0005] Furthermore, the PFU receiver (receiving device) is composed of the receiving high-frequency unit 1 and the receiving control unit 2. Furthermore, the FPU receiving base station and the receiving equipment are usually located separately, and the two are connected by wiring in a waveguide 7, forming a conventional FPU receiving base station system.

[0006] Here, because the rotating base 4 of the FPU receiving base station and the receiving high-frequency section 1 of the receiving device are separated, signal level attenuation occurs due to the connecting waveguide 7. Therefore, after receiving with the antenna 4, the received signal is amplified by the LNA 5, and the amplified signal is output to the receiving high-frequency section 1 of the receiving device via the waveguide 7.

[0007] Then, in the receiving high-frequency section 1 of the receiving device, the gain is controlled to an appropriate level and the frequency is converted. In the receiving control section 2, demodulation processing is performed to obtain the received signal (TS [Transport Stream] signal), which is then output externally.

[0008] In this case, the conventional RSSI value is calculated based on the detection level of the received signal input to the receiving high-frequency unit 1, and the user uses this RSSI value as an important indicator for understanding the reception status.

[0009] The RSSI value is a value that indicates the strength of the radio signal received by a receiver from a connected device in wireless communication. It is expressed in dBm (decibels / milliwatts), and a higher value indicates a stronger signal and is more suitable for communication.

[0010] In the conventional receiving base station system shown in Figure 4, the RSSI value, which indicates the strength of the received signal, passes through the LNA 5, BPF 6, and waveguide 7 when it is input to the receiving high-frequency unit 1, resulting in a value different from the RSSI value after actual reception by the antenna 3.

[0011] For example, if the gain at LNA5 is set to +20dB and the total loss at BPF6 and waveguide7 is 3dB, the total amplification will be +17dB. However, if the RSSI value received by antenna3 is -80dBm, the RSSI value detected by the receiving high-frequency section 1 via LNA5, etc., will be -63dBm.

[0012] In a transmission system using OFDM (Orthogonal Frequency Division Multiplexing) signals compliant with ARIB STD B33 as described in Non-Patent Document 1, if the transmission parameters are 64QAM (Quadrature Amplitude Modulation) modulation and the coding rate is 5 / 6, the required C / N ratio (Carrier / Noise) is approximately 21 dB. The RSSI value at this time corresponds to -76 dBm.

[0013] [Related technologies] Furthermore, related prior art includes Japanese Patent Publication No. 2021-180348 "Method for displaying reception status, receiving device" (Patent Document 1), Japanese Patent Publication No. 2007-251705 "Method for displaying transmission status" (Patent Document 2), Japanese Patent Publication No. 2007-104087 "Digital transmission device" (Patent Document 3), and Japanese Patent Publication No. 2006-157337 "Digital transmission system and method for displaying transmission status" (Patent Document 4).

[0014] Patent Document 1 describes a receiving device that displays the reception status based on a virtual BER corresponding to the calculated BER. Patent Document 2 describes a multi-stage relay transmission system that superimposes reception status information at each relay stage and information identifying each relay stage and transmits it to the next stage.

[0015] Patent Document 3 describes a digital transmission device that analyzes the frequency components of an IF signal from a receiving high-frequency section and displays the frequency components in the X-axis direction and the demodulated signal components in the Y-axis direction in two dimensions. Patent Document 4 discloses a digital transmission system that receives information regarding the reception state of a transmission signal from a reception high-frequency unit and a reception control unit, generates reception auxiliary information, and multiplexes the reception auxiliary information with the transmission signal.

Prior Art Documents

Patent Documents

[0016]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0017]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0018] However, in a conventional FPU receiving base station system, in reality, although the RSSI value when received by the antenna is -80 dBm (a degraded quality signal with a C / N ratio of 17 dB and a required C / N ratio of less than 21 dB), the gain is increased by the LNA and the RSSI value becomes -63 dBm, so there is a problem that a user may erroneously judge that a good quality signal with an RSSI value at the reception limit point being sufficiently higher than -76 dBm is being received.

[0019] Furthermore, Patent Documents 1 to 4 do not describe a configuration for outputting an appropriate RSSI value corresponding to the signal quality of the actual received signal received by the antenna.

[0020] The present invention has been made in view of the above actual situation, and an object thereof is to provide a receiving device and a receiving method capable of obtaining an appropriate RSSI value corresponding to the signal quality of an actual received signal received by an antenna.

Means for Solving the Problems

[0021] The present invention for solving the problems of the above conventional example is a receiving device that receives a digitally modulated signal, and includes a digital demodulation unit that digitally demodulates a received signal, a reception quality level calculation unit that calculates a reception quality level from the digitally demodulated received signal, and an RSSI conversion unit that converts the calculated quality level into an RSSI value and outputs it as a virtual RSSI value when received by an antenna.

[0022] The present invention is characterized in that, in a receiving device, it includes an RSSI detection unit that detects an RSSI value from a received signal, and a display unit that inputs the RSSI value detected by the RSSI detection unit and the virtual RSSI value output from the RSSI conversion unit and displays the detected RSSI value and the virtual RSSI value.

[0023] The present invention is characterized in that, in a receiving device, a low-noise amplifier unit that amplifies a received signal and a frequency conversion unit that converts the amplified received signal into an intermediate frequency and outputs it to a digital demodulation unit are provided in front of the digital demodulation unit, and an error correction decoding unit that performs error correction processing on the digitally demodulated received signal is provided after the digital demodulation unit.

[0024] The present invention is characterized in that, in a receiving device, the reception quality level calculation unit obtains a modulation error ratio corresponding to a modulation method, calculates a C / N ratio from the modulation error ratio, the RSSI conversion unit includes a correspondence table showing the relationship between the C / N ratio and the RSSI value, and the C / N ratio calculated by the reception quality level calculation unit is converted into an RSSI value by the correspondence table to obtain a virtual RSSI value.

[0025] The present invention is a receiving method for receiving a digitally modulated signal, characterized by digitally demodulating the received signal, calculating a reception quality level from the digitally demodulated received signal, converting the calculated quality level into an RSSI value, and outputting it as a virtual RSSI value as if received by an antenna. [Effects of the Invention]

[0026] According to the present invention, the receiving device includes a digital demodulation unit that digitally demodulates the received signal, a received quality level calculation unit that calculates the received quality level from the digitally demodulated received signal, and an RSSI conversion unit that converts the calculated quality level into an RSSI value and outputs it as a virtual RSSI value when received by the antenna. Therefore, it has the effect of being able to output an appropriate RSSI value as a virtual RSSI value that corresponds to the signal quality of the actual received signal received by the antenna. [Brief explanation of the drawing]

[0027] [Figure 1] This is a schematic diagram of the configuration of this receiving device. [Figure 2] This figure shows a table relating RSSI value to the C / N ratio. [Figure 3] This is a schematic diagram showing an example of how RSSI values ​​are displayed. [Figure 4] This is a schematic diagram of a conventional FPU receiving base station system. [Modes for carrying out the invention]

[0028] Embodiments of the present invention will be described with reference to the drawings. [Summary of the Embodiment] The receiving device according to an embodiment of the present invention (this receiving device) detects an RSSI value (detected RSSI value) from the input received signal using an RSSI detection unit provided in the receiving high-frequency section, calculates the signal quality level using a signal quality level calculation unit from the digitally demodulated data in the receiving control unit, converts it into an RSSI (virtual RSSI) value corresponding to the signal quality of the actual received signal (received signal received by the antenna) using a virtual RSSI conversion unit, and displays the virtual RSSI value and the detected RSSI value in an RSSI output display unit, making it possible to recognize the detected RSSI value and the virtual RSSI value in a comparable manner.

[0029] [This receiving device: Figure 1] This receiving device will be explained with reference to Figure 1. Figure 1 is a schematic diagram of the configuration of this receiving device. This receiving device is installed in the same way as the receiving device in the FPU receiving base station system described in Figure 4, but its specific internal configuration is different. As shown in Figure 1, this receiving device consists of a receiving high-frequency unit 10 and a receiving control unit 20.

[0030] [Receiver high-frequency section 10] The receiving high-frequency section 10 consists of a low-noise amplification section (LNA section) 11, a frequency conversion section 12, and an RSSI detection section 13.

[0031] [Low-noise amplification section (LNA section) 11] The low-noise amplification unit (LNA unit) 11, similar to the LNA 5 in Figure 4, receives the signal (received signal) from the BPF 6 of the rotating base 4 via the waveguide 7, adjusts it to an optimal level by increasing the gain, and outputs it to the frequency conversion unit 12.

[0032] [Frequency conversion unit 12] The frequency conversion unit 12 converts the adjusted received signal from the LNA unit 11 to an intermediate frequency (downconverts) to generate an IF (Intermediate Frequency) signal, which is then output to the digital demodulation unit 21 of the receiving control unit 20.

[0033] [RSSI detection unit 13] The RSSI detection unit 13 receives the received signal from the BPF 6 via the waveguide 7, detects the input received signal level when it is input to the receiving high-frequency unit 10, converts it to an RSSI value, and outputs it to the RSSI output display unit 25 of the receiving control unit 20. The RSSI value detected by the RSSI detection unit 13 will be called the "detected RSSI value".

[0034] [Receiver control unit 20] The reception control unit 20 consists of a digital demodulation unit 21, an error correction decoding unit 22, a signal quality level calculation unit 23, a virtual RSSI conversion unit 24, and an RSSI output display unit 25.

[0035] [Digital demodulation unit 21] The digital demodulation unit 21 receives the IF signal converted by the frequency conversion unit 12 of the receiving high-frequency unit 10, demodulates it according to the modulation scheme, such as OFDM, and outputs it to the error correction decoding unit 22 and the signal quality level calculation unit 24.

[0036] [Error correction / decoding unit 22] The error correction decoding unit 22 performs error correction processing on the digitally demodulated digital signal from the digital demodulation unit 21 and outputs the TS signal externally. The error correction processing in the error correction decoding unit 22 improves the code error rate (BER: Bit Error Rate) of the digital signal. Here, BER generally depends on the RSSI value; a smaller RSSI value results in a larger BER, and a larger RSSI value results in a smaller BER.

[0037] [Signal quality level calculation unit 23] The signal quality level calculation unit 23 receives the digital signal from the digital demodulation unit 21 and calculates the signal quality level of the currently received signal. The signal quality level to be calculated is the signal-to-noise ratio (C / N ratio). Specifically, the signal quality level calculation unit 23 obtains the modulation error ratio (MER) in the constellation according to the OFDM modulation scheme by the digital demodulation unit 21.

[0038] Here, constellation is a method of representing the evaluation of digital modulation using points on the IQ coordinate system. MER is a numerical representation of the difference between the amplitude and phase transmitted from the transmitting device and the actual amplitude and phase of the received digital signal in terms of digital modulation (amplitude and phase), and its unit is dB. A MER of 40 dB or higher indicates good reception.

[0039] Furthermore, there is a certain relationship between MER and C / N ratio, and the signal quality level calculation unit 23 calculates the C / N ratio of the currently received signal based on this relationship. There is a correlation between MER and C / N ratio; generally, a higher MER tends to correlate with a higher C / N ratio, while a lower MER tends to correlate with a lower C / N ratio. The signal quality level calculation unit 23 stores a calculation formula or conversion table for calculating the C / N ratio from MER based on this correlation, and calculates the C / N ratio using the calculation formula or the like.

[0040] [Virtual RSSI conversion unit 24: Figure 2] The virtual RSSI conversion unit 24 converts the C / N ratio calculated by the signal quality level calculation unit 23 into an RSSI value (virtual RSSI value) that would be expected when received by the antenna 3. Specifically, the virtual RSSI conversion unit 24 includes a relationship table between RSSI values ​​and the C / N ratio shown in Figure 2. It refers to this table to convert the C / N ratio to an RSSI value and outputs it as a virtual RSSI value. Figure 2 shows a table illustrating the relationship between RSSI value and C / N ratio.

[0041] In an FPU receiving base station system, for transmission paths with good line of sight and basically no reflected waves or fading fluctuations, the relationship between the RSSI value and the C / N ratio is uniquely determined, as shown in Figure 2. Generally, the C / N ratio depends on the RSSI value; a higher RSSI value results in a higher C / N ratio.

[0042] [RSSI output display section 25] The RSSI output display unit 25 receives the detected RSSI value from the RSSI detection unit 13 of the receiving high-frequency unit 10 and the virtual RSSI value from the virtual RSSI conversion unit 24, and displays the detected RSSI value (current) and the virtual RSSI value (virtual) on the display screen using indicator bars.

[0043] [Example of RSSI value display: Figure 3] An example of how RSSI values ​​are displayed on the display screen of the RSSI output display unit 25 will be explained with reference to Figure 3. Figure 3 is a schematic diagram showing an example of how RSSI values ​​are displayed. As shown in Figure 3, the display screen shows the detected RSSI value (current) and the virtual RSSI value (virtual) using LEDs to illuminate an indicator with both numerical values ​​and RSSI value scales, representing the two constantly fluctuating RSSI values. This allows the user to easily compare and understand the detected RSSI value and the virtual RSSI value.

[0044] In this receiving device, two RSSI values, the detected RSSI value and the virtual RSSI value, are displayed on the display screen of the RSSI output display unit 25, but they may also be displayed on an external display device.

[0045] [Effects of the embodiment] According to this receiving device, the RSSI detection unit 13 in the receiving high-frequency unit 10 detects the RSSI value from the input received signal, the signal quality level calculation unit 23 in the receiving control unit 20 calculates the signal quality level from the received signal digitally demodulated by the digital demodulation unit 21, the virtual RSSI conversion unit 24 converts it into a virtual RSSI value corresponding to the signal quality of the actual received signal received by the antenna, and the RSSI output display unit 25 displays the virtual RSSI value and the detected RSSI value. This has the effect of making the detected RSSI value and the virtual RSSI value comparable and recognizable. [Industrial applicability]

[0046] The present invention is suitable for a receiving device and receiving method that can obtain an appropriate RSSI value corresponding to the signal quality of the actual received signal received by an antenna. [Explanation of Symbols]

[0047] 1…Receiver high-frequency section, 2…Receiver control section, 3…Antenna, 4…Rotating stand, 5…Low-noise amplifier (LNA), 6…Bandwidth filter (BPF), 7…Waveguide, 10…Receiver high-frequency section, 11…Low-noise amplification section (LNA section), 12…Frequency conversion section, 13…RSSI detection section, 20…Receiver control section, 21…Digital demodulation section, 22…Error correction decoding section, 23…Signal quality level calculation section, 24…Virtual RSSI conversion section, 25…RSSI output display section

Claims

1. A receiving device for receiving digitally modulated signals, A digital demodulation unit that digitally demodulates the received signal, A reception quality level calculation unit calculates the reception quality level from the digitally demodulated received signal, A receiving device characterized by having an RSSI conversion unit that converts the calculated quality level into an RSSI value and outputs it as a virtual RSSI value when received by an antenna.

2. An RSSI detection unit that detects the RSSI value from the received signal, The receiving device according to claim 1, further comprising: a display unit that receives the RSSI value detected by the RSSI detection unit and a virtual RSSI value output from the RSSI conversion unit, and displays the detected RSSI value and the virtual RSSI value.

3. Prior to the digital demodulation unit, a low-noise amplification unit for amplifying the received signal and a frequency conversion unit for converting the amplified received signal to an intermediate frequency and outputting it to the digital demodulation unit are provided. The receiving device according to claim 1 or 2, further characterized in that an error correction decoding unit is provided after the digital demodulation unit to perform error correction processing of the digitally demodulated received signal.

4. The reception quality level calculation unit obtains a modulation error ratio according to the modulation scheme, calculates the C / N ratio from the modulation error ratio, The receiving device according to claim 1 or 2, wherein the RSSI conversion unit includes a correspondence table showing the relationship between the C / N ratio and the RSSI value, and the C / N ratio calculated by the receiving quality level calculation unit is converted to an RSSI value using the correspondence table to obtain a virtual RSSI value.

5. A receiving method for receiving a digitally modulated signal, The received signal is digitally demodulated, The reception quality level is calculated from the digitally demodulated received signal. A receiving method characterized by converting the calculated quality level into an RSSI value and outputting it as a virtual RSSI value when received by an antenna.

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