KR100848835B1 - Digital optical repeater and digital signal processing method in the repeater - Google Patents

Abstract

A digital optical repeater and a digital signal processing method in the digital optical repeater are provided to detect the power level of an RF signal by digital signal processing without using a separate device and control the gain of the RF signal by digital signal processing without using an additional device, thereby improving the accuracy of gain control in the digital optical repeater. A digital optical repeater includes an MHU(Main Hub Unit)(2A) and an ROU(Remote Optic Unit)(3A). The ROU includes a digital signal processing module(32A) and a control module(38A). The digital signal processing module processes forward and backward digital signals, detects forward and backward RF(Radio Frequency) signal power level data, transmits the detected data to the control module, operates gain control data for the forward and backward RF signals received from the control module to inputted forward and backward digital signals, and controls the gain of the forward and backward RF signals by digital. The control module has forward and backward gain control information tables, searches forward and backward gain control data corresponding to the forward and backward RF signal power level data from the digital signal processing module on the forward and backward gain control information tables and transmits corresponding gain control data to the digital signal processing module.

Description

Digital optical repeater system and digital signal processing method in the digital optical relay system {Digital optical repeater and digital signal processing method in the repeater}

The present invention relates to a digital optical relay system, and more particularly, to a digital optical relay system for digitally detecting a power level of an RF signal and digitally adjusting a gain of the RF signal, and a digital signal in the digital optical relay system. It is about a processing method.

In an example of a conventional digital optical relay system, as shown in FIG. 1, a down conversion module (in a main hub unit) hereinafter referred to as “MHU” 2 receiving a signal from a base station 1 ( 21 to an intermediate frequency, and converts the intermediate frequency into a digital signal in the signal processing module 22 and converts the intermediate frequency into an optical signal through a digital optical module 23 and an optical cable. ROU 'is abbreviated) (3). Accordingly, the optical signal received by the digital optical module 31 of the ROU 3 is converted into an electrical signal, and the signal processing module 32 converts the analog signal into an analog intermediate frequency and then inputs it to the up-conversion module 33. The up-conversion module 33 converts the analog intermediate frequency into an RF signal, amplifies the linear frequency amplifier (LPA) module 34 or the high power amplifier (HPA) module, and then uses the duplexer 35 and the antenna. Through the high power output to the subscriber terminal (4) side.

The signal from the subscriber station 4 side is inversely opposite to the signal from the base station 1, the duplexer 35 of the ROU 3, the low noise amplifier (LNA) 36, and the down conversion module 37. The base station 1 through the digital optical module 23, the signal processing module 22, the up-conversion module 24 and the antenna of the MHU 2 through the signal processing module 32 and the digital optical module 31. Radiated to the side.

As shown in FIG. 2, the MHU 2 includes an attenuator in the down-conversion module 21 and the up-conversion module 24, and is input from the base station 1 in the control module 25. The downconversion module 21 and the upconversion module 24 are detected by detecting a power level of the RF signal and controlling the attenuators of the downconversion module 21 and the upconversion module 24 based on the detected power level of the RF signal. Adjust the gain for In addition, the ROU 3 includes an attenuator in the down-conversion module 37 and the up-conversion module 33, and detects the power level of the RF signal input from the subscriber station 4 in the control module 38. The gain for the downconversion module 37 and the upconversion module 33 is adjusted by controlling the attenuators of the downconversion module 37 and the upconversion module 33 based on the detected power level of the RF signal.

Meanwhile, in another example of the conventional digital optical relay system, as shown in FIGS. 3 and 4, the MHU 2 is the same as the example of FIG. 1, but in the ROU 3_1, the analog processing is performed by the signal processing module 32. The digital signal processor 32_2 of the signal processing module 32 (see FIG. 4) is not processed by the up-conversion module, the linear power amplifier (LPA) module, or the high power amplifier (HPA) with respect to the forward signal after the conversion to frequency. And a low voltage differential signaling (LVDS) processor 32_3 (refer to FIG. 4) are processed by a digital predistortion (DPD) method. Process the same as

That is, even in this example, as shown in FIG. 4, the MHU 2 includes an attenuator in the down-conversion module 21 and the up-conversion module 24, and from the base station 1 in the control module 25. By detecting the power level of the input RF signal and controlling the attenuators of the downconversion module 21 and the upconversion module 24 based on the detected power level of the RF signal, the downconversion module 21 and the upconversion module ( Adjust the gain for 24). In addition, the ROU 3 includes an attenuator in the down conversion module 37, and the control module 38 detects the power level of the RF signal input from the subscriber station 4, and then the power of the detected RF signal. The gain for the downconversion module 37 is adjusted by controlling the attenuator of the downconversion module 37 based on the level.

In the conventional optical relay system configured as described above, the gains for the downconversion module 21, 37 and the upconversion module 24, 33 are controlled by the control modules 25 and 38. As it is performed in the analog section, the accuracy or the RF signal is distorted in the gain control process due to the characteristics of the RF frequency, and there is a problem that it is affected by the environmental factors.

In addition, in the conventional digital optical relay system, a separate RF signal detection element is required in the down conversion module to measure the power of the RF signal, and an attenuator is required in the down conversion module and the up conversion module to adjust the gain for the RF signal. Accordingly, there is a problem that the unit cost of the down-conversion module and the up-conversion module increases, and the size of those modules also increases.

In addition, in the digital optical relay system adopting the digital predistortion (DPD) method as shown in Figs. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and detects an RF signal level from an input digital signal and adjusts a gain without using additional elements in a signal processing module which is essentially used in a digital optical relay system. The purpose of the present invention is to provide a digital optical relay system that provides a stable wireless mobile communication environment by increasing the accuracy of the gain control and the stability of the overall RF characteristics by adjusting the gain of the RF signal digitally without using additional devices. .

In addition, the present invention detects the RF signal level from the input digital signal without the use of additional elements and adjusts the gain of the RF signal digitally without the use of additional elements to adjust the gain. Another object of the present invention is to provide a digital signal processing method in a digital optical relay system that provides a stable wireless mobile communication environment by increasing the stability of the system.

In order to achieve the above object, a digital optical relay system according to the present invention includes a main hub unit (Main Hub Unit) for wireless communication with a base station, and the main hub unit is connected through an optical cable and wirelessly communicates with a subscriber station. In the digital optical relay system including a remote optical unit (Remote Optic Uint), the remote optical unit, by processing the forward and reverse digital signal to detect the forward and reverse RF signal power level data from the input digital signal Digital signal processing to digitally control gain of forward and reverse RF signal by transmitting to control module and numerically calculating gain adjustment data of forward and reverse RF signal received from control module to input forward and reverse digital signal. A module; A forward and reverse gain adjustment information table, and forward and reverse gain adjustment data corresponding to forward and reverse RF signal power level data from the digital signal processing module are found in the forward and reverse gain adjustment information tables. And a control module for transmitting the gain control data to the digital signal processing module.

In addition, the digital signal processing method in the digital optical relay system according to the present invention in order to achieve the above object, the main hub unit for wireless communication with the base station, the main hub unit is connected via an optical cable and the subscriber terminal 10. A digital optical relay system comprising a remote optical unit in wireless communication with a remote optical unit, the remote optical unit comprising: processing forward and reverse digital signals to detect forward and reverse RF signal power level data from an input digital signal; ; Searching for gain adjustment data corresponding to the detected forward and reverse RF signal power level data in a forward and backward gain adjustment information table; And adjusting the gain of the forward and reverse RF signals digitally by numerically calculating the gain control data for the found forward and reverse RF signals to the input forward and reverse digital signals.

According to the present invention configured as described above, the power level of the RF signal is detected by digital signal processing without using a separate device for measuring the power level of the RF signal, and without the use of an additional device for adjusting the gain. Since the gain of the RF signal is adjusted by digital signal processing, its accuracy is relatively excellent. In addition, it is possible to implement a more stable digital optical repeater system because it is less affected by the surrounding environment factors without affecting the RF characteristics.

In addition, in the digital optical relay system adopting the conventional digital predistortion (DPD) method, gain control was not possible because the upconverter does not exist in the remote optical unit (ROU). It is possible to improve the stability of the.

Hereinafter, a digital optical relay system and a digital signal processing method in the digital optical relay system according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a diagram for describing the configuration of a down conversion module, an up conversion module, a signal processing module, and a control module in a main hub unit (MHU) and a remote optical unit (ROU) in a digital optical relay system according to an embodiment of the present invention. It is a block diagram.

As shown in the figure, in the digital optical relay system according to an embodiment of the present invention, an attenuator for adjusting the gain of the RF signal is required for the down conversion module 21A and the up conversion module 24A of the MHU 2A. In addition, an element for measuring the power level of the RF signal coming from the base station is not required, and the control module 25A of the MHU 2A controls the gain of the downconversion module 21A and the upconversion module 24A. Do not do it.

In addition, in the digital optical relay system according to the embodiment of the present invention, the down conversion module 31A and the up conversion module 37A of the ROU 3A do not need an attenuator for adjusting the gain of the RF signal, and the user terminal. No element for measuring the power level of the RF signal coming from the side is required, and the control module 25A of the ROU 3A does not perform the gain control of the down conversion module 21A and the up conversion module 24A.

In the digital signal processor 32_1A constituting the signal processing module 32A of the ROU 3A, the digital signal in the forward direction is inputted through the digital optical module 31 to signal the forward RF signal power level from the input digital signal. Digitally forward by detecting and forwarding this forward RF signal power level to the control module 38A and numerically calculating gain adjustment data for the forward RF signal received from the control module 38A to the incoming digital signal. The gain of the RF signal is adjusted. Accordingly, the digital signal in the forward direction in which the gain of the RF signal is adjusted is converted into an analog signal in the signal conversion module 32_1 and output to the uplink conversion module 33 in the forward direction.

On the other hand, the reverse RF signal input through the reverse conversion module 37A in the reverse direction is converted into a digital signal by the signal conversion module 32_1 is input to the digital signal processor 32_2A. The digital signal processor 32_1A performs a signal processing on an input reverse digital signal to detect a reverse RF signal power level from the input digital signal, and transmits the reverse RF signal power level to the control module 38A, and controls the control module 38A. Digitally adjusts gain of the reverse RF signal by numerically calculating the gain control data for the reverse RF signal received from the digital signal of the reverse direction. Transmit to MHU (2A) side.

The control module 38A includes forward and reverse gain control information tables, and forward and reverse gain control data corresponding to forward and reverse RF signal power levels detected and transmitted by the digital signal processor 32_2A. The gain control data is found in the forward and reverse gain control information tables, and the gain control data is transmitted to the digital signal processor 32_2A.

The digital signal processor 32_2A may be configured as a field-programmable gate array (FPGA).

Also, except for the above points, the MHU 2A and the ROU 3A are the same as the conventional configurations shown in Figs.

FIG. 6 is a diagram for describing the configuration of a down conversion module, an up conversion module, a signal processing module, and a control module in a main hub unit (MHU) and a remote optical unit (ROU) in a digital optical relay system according to another embodiment of the present invention. It is a block diagram.

As shown in the figure, in the digital optical relay system according to another embodiment of the present invention, RF is applied to the down-conversion module 21A and the up-conversion module 24A of the MHU 2A similarly to the embodiment of FIG. 5 described above. There is no need for an attenuator to adjust the gain of the signal, and no element for measuring the power level of the RF signal coming from the base station side, and the control module 25A of the MHU 2A includes the down conversion module 21A and Gain control of the up-conversion module 24A is not performed.

In addition, the operations of the digital signal processor 32_2A and the control module 38A in the digital optical relay system according to the present embodiment are substantially the same as those of the above-described embodiment of FIG. 5.

Next, an operation of detecting and gain control of the RF signal power level in the digital signal processing unit 32_2A of the digital optical relay system according to the present invention will be described in detail.

The analog signal goes through the analog-to-digital converter, and the magnitude of the digital signal changes according to the power level of the analog signal. However, since each digital signal digitized by the sampling clock cannot measure the power level of the entire analog signal, if you add more than a certain number of consecutive digital signals and divide them by the number of times, the digital signal shows a constant value per analog level. .

Using this principle, if the RF signal entered into the signal processing module 22 through the down conversion module 21A of the MHU 2A is the power level of the analog signal of a predetermined value, this is performed by the signal conversion unit 22_1. The digital conversion is converted into a 14-bit digital signal and input to the digital signal processing unit 32_2A of the signal processing module 32A of the ROU 3A via the optical modules 23 and 31. For example, the digital signal inputted to the digital signal processor 32_2A may be input. When using a 50MHz sampling clock, for example when the share to ²²⁶ after adding a continuous digital signal of ²²⁶ as (i.e., ask an average value of the digital signal that is continuous in a predetermined period) constant digital value with a power level of the analog (S1 in FIG. 7). The digital signal processor 32_2A sends a constant digital value having an analog power level to the control module 38A (S2 in FIG. 7).

The control module 38A searches for 14-bit gain control data corresponding to the digital value transmitted from the digital signal processor 32_2A in the forward gain control information table set by the user, and converts the gain control data into the digital signal. It sends to the processing part 32_2A (S5-S7 of FIG. 7).

The digital signal processor 32_2A performs numerical calculation (for example, addition) of the gain adjustment data on the 14-bit digital signal input from the optical module 31 (S9 to S11 in FIG. 7). In the embodiment of FIG. 5, the output data is converted into an analog signal by the signal conversion module 32_1 and transferred to the up conversion module 33A. In the embodiment of FIG. 6, the output data is passed through a low voltage differential signaling (LVDS) processor. It is passed to module 39.

On the other hand, in the reverse direction, if the RF signal entering the signal processing ah module 32A through the down conversion converter 37A of the ROU 3A is the power level of the analog signal of a predetermined value, it is converted into a 12-bit digital signal and It is input to the signal processor 32_2A. When the digital signal processing, for example in (32_2A) using a 50MHz sampling clock, for example when the share to ²²⁶ after adding a continuous digital signal of ²²⁶ as (i.e., ask an average value of the digital signal that is continuous in a predetermined length ) Is a constant digital value having an analog power level (S1 in FIG. 7). The digital signal processor 32_2A sends a constant digital value having an analog power level to the control module 38A (S3 in FIG. 7).

The control module 38A finds 12 bits of gain control data corresponding to the digital value transmitted from the digital signal processor 32_2A in the reverse gain control information table set by the user, and converts the gain control data into the digital signal. It sends to the processing part 32_2A (S5-S7 of FIG. 7).

The digital signal processor 32_2A performs numerical calculation (for example, adding) on the gain control data to an input 12-bit digital signal in the reverse direction, and outputs the digital result. This output signal is input to the signal processing module 22 of the MHU 22 via the optical modules 31 and 23, converted into an analog signal, and outputted (S9 to S11 in FIG. 7).

Next, the analog power level detection and the gain control of the forward digital signal in the digital signal processor 32_2A and the control module 38A will be described with specific examples.

For example, the user has set the range of the forward analog input power tolerance level from -15 to -20 dBm, and the actual analog power input levels are -10 dBm (over input), -17 dBm (input for gkj), -25 dBm ( Assume that there are three kinds of low input.

1) When a forward analog signal input power level of -10 dBm (over input) is input (see Table 1).

The digital signal processing section 32_2A of the signal processing module 32A averages the continuous 14-bit forward digital signals to obtain a constant digital value (hexacode: 0FF5) having an analog power level of -10 dBm. Hexa code: 0FF5) is transferred to the control module 38A. Accordingly, the control module 38A compares the digitized data (hexacode: 1FBD) of the maximum analog input power level and sends data (hexacode: 0FC8) of the difference to the digital signal processor 32_2A. The signal processor 32_2A adds this data (hexa code: 0FC8) to the input 14-bit forward digital signal to attenuate the power level of the analog signal to output the power level of the analog signal of -15 dBm.

2) When a forward analog signal input power level of -17 dBm (allowed input) is input (see Table 2).

The digital signal processing unit 32_2A of the signal processing module 32A obtains a constant digital value (hexa code: 208C) having an analog power level of -17 dBm by averaging successive 14-bit forward digital signals, and calculating the digital value ( Hexa code: 208C) is transmitted to the control module 38A. Accordingly, the control module 38A compares the digitized information (hexacode: 1FBD to 2BC6) of the analog input power allowance level and sends the information (hexacode: 0000) on the difference to the digital signal processor 32_2A. The digital signal processor 32_2A adds this data (hexa code: 0000) to the 14-bit forward digital signal to be input to maintain the power level of the analog signal.

3) When a forward analog signal input power level of -25 dBm (low input) is input (see Table 3).

The digital signal processing section 32_2A of the signal processing module 32A obtains a constant digital value (hexa code: 27EF) having an analog power level of -25 dBm by averaging successive 14-bit forward digital signals, and this digital value ( Hexa code: 27EF) is transmitted to the control module 38A. Accordingly, the control module 38A compares the digitized data of the minimum analog input power level (hexa code: 2BC6) and sends data (hexa code: 03D7) of the difference to the digital signal processor 32_2A. The signal processor 32_2A adds this data (hexa code: 03D7) to the input 14-bit forward digital signal to increase the power level of the analog signal and output the power level of the analog signal of -20 dBm.

 Next, analog power level detection and gain control of the reverse digital signal in the digital signal processor 32_2A and the control module 38A will be described with reference to specific examples.

For example, the user has set the range for the reverse analog input power tolerance level from -15 to -20 dBm, and the actual analog power input levels are -10 dBm (over input), -17 dBm (allowed input), and -25 dBm (low). Assume three kinds of input).

1) When a reverse analog signal input power level of -10 dBm (over input) is input (see Table 1)

The digital signal processing section 32_2A of the signal processing module 32A averages successive 12-bit reverse digital signals to obtain a constant digital value (hexacode: 3FD) having an analog power level of -10 dBm. Hexa code: 3FD) is transmitted to the control module 38A. Accordingly, the control module 38A compares the digitized data of the maximum analog input power level (hexacode: 5CD) and sends the data (hexacode: 1D0) of the difference to the digital signal processor 32_2A. The signal processor 32_2A adds this data (hexa code: 1D0) to the input 12-bit reverse digital signal to attenuate the power level of the analog signal and output the power level of the analog signal of -15 dBm.

2) When a reverse analog signal input power level of -17 dBm (allowed input) is input (see Table 2)

The digital signal processor 32_2A of the signal processing module 32A obtains a constant digital value (hexa code: 6A3) having an analog power level of -17 dBm by averaging successive 12-bit reverse digital signals, and calculating the digital value ( Hexa code: 6A3) is transferred to the control module 38A. Accordingly, the control module 38A compares the digitized information (hexacode: 5CD to 7EF) of the analog input power allowance level and sends the information (hexacode: 000) on the difference to the digital signal processor 32_2A. The digital signal processor 32_2A adds this data (hexa code: 000) to the input 12-bit reverse digital signal to maintain the power level of the analog signal.

3) When a reverse analog signal input power level of -25 dBm (low input) is input (see Table 3)

The digital signal processing section 32_2A of the signal processing module 32A obtains a constant digital value (hexacode: 9CB) having an analog power level of -25 dBm by averaging successive 12-bit reverse digital signals, and calculating the digital value ( Hexa code: 9CB) is transferred to the control module 38A. Accordingly, the control module 38A compares the digitized data of the minimum analog input power level (hexa code: 7EF) and sends the data (hexa code: 1DE) of the difference to the digital signal processor 32_2A. The signal processor 32_2A adds this data (hexa code: 1DE) to the input 12-bit reverse digital signal to increase the power level of the analog signal and output the power level of the analog signal of -20 dBm.

<Table 1> Conversion table for analog signal over input

Forward direction Reverse Input power level analog -10 dBm -10 dBm digital 0FF5 3FD Permissible power level (user setting) analog -15 to -20 dBm -15 to -20 dBm digital 1FBD ~ 2BC6 5CD to 7EF Signal gain adjustment information analog -5 dB -5 dB digital 0FC8 5CD Output power level analog -15 dBm -15 dBm digital 1FBD 5CD

<Table 2> Conversion Table for Analog Signal Tolerance Input

Forward direction Reverse Input power level analog -17 dBm -17 dBm digital 208C 6A3 Permissible power level (user setting) analog -15 to -20 dBm -15 to -20 dBm digital 1FBD ~ 2BC6 5CD to 7EF Signal gain adjustment information analog 0 0 digital 0000 0000 Output power level analog -17 dBm -17 dBm digital 208C 6A3

<Table 3> Conversion table for analog signal low input

Forward direction Reverse Input power level analog -25 dBm -25 dBm digital 27EF 9CB Permissible power level (user setting) analog -15 to -20 dBm -15 to -20 dBm digital 1FBD ~ 2BC6 5CD to 7EF Signal gain adjustment information analog +5 dB +5 dB digital 03D7 1DE Output power level analog -20 dBm -20 dBm digital 2BC6 7EF

As described above, according to the present invention, the digital signal processing detects the power level of the RF signal without using a separate device for measuring the power level of the RF signal, and does not use an additional device for adjusting the gain. Since the gain of the RF signal is adjusted by signal processing, its accuracy is relatively excellent. In addition, it is possible to implement a more stable digital optical repeater system because it is less affected by the surrounding environment factors without affecting the RF characteristics.

On the other hand, the present invention is not limited to the above specific embodiments, it can be carried out by various modifications and variations within the scope not departing from the gist of the present invention. If such changes and modifications fall within the scope of the appended claims, it will be apparent that they are included in the present invention.

1 is a configuration diagram of an example of a conventional digital optical relay system.

FIG. 2 is a diagram illustrating a relationship between a down conversion module, an up conversion module, a signal processing module, and a control module in the main hub unit MHU and the remote optical unit ROU shown in FIG. 1.

3 is a configuration diagram of another example of a conventional digital optical relay system.

4 is a configuration diagram illustrating a relationship between a down conversion module, an up conversion module, a signal processing module, and a control module in the main hub unit MHU and the remote optical unit ROU shown in FIG. 3.

FIG. 5 is a diagram for describing the configuration of a down conversion module, an up conversion module, a signal processing module, and a control module in a main hub unit (MHU) and a remote optical unit (ROU) in a digital optical relay system according to an embodiment of the present invention. It is a block diagram.

FIG. 6 is a diagram for describing the configuration of a down conversion module, an up conversion module, a signal processing module, and a control module in a main hub unit (MHU) and a remote optical unit (ROU) in a digital optical relay system according to another embodiment of the present invention. It is a block diagram.

7 is a flowchart illustrating a digital signal processing process in the digital optical relay system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1: base station 2, 2A: main hub unit (MHU)

3, 3_1, 3A, 3_1A: Remote Optical Unit (ROU)

4: terminal 21, 21A: forward down conversion module

22: signal processing module 23: digital optical module

24, 24A: reverse up-conversion module 25, 25A: control module

31: digital optical module 32, 32A: signal processing module

33, 33A: Forward Up Conversion Module 34: Low Power Amplifier Module

35: duplexer 36: low noise amplifier

37, 37A: reverse down conversion module 38, 38A: control module

39: digital predistortion (DPD) module

Claims (5)

delete delete A digital optical relay system including a main hub unit for wireless communication with a base station and a remote optic unit connected to the main hub unit via an optical cable and for wireless communication with a subscriber station. To The remote optical unit processes forward and reverse digital signals to detect forward and reverse RF signal power level data from an input digital signal, and transmits the received power to the control module, and adjusts gains of the forward and reverse RF signals received from the control module. A digital signal processing module that digitally adjusts gains of the forward and reverse RF signals by numerically calculating data to digital signals in forward and reverse directions; A forward and reverse gain adjustment information table, and forward and reverse gain adjustment data corresponding to forward and reverse RF signal power level data from the digital signal processing module are found in the forward and reverse gain adjustment information tables. It includes a control module for transmitting the gain control data to the digital signal processing module, In the digital signal processing module, the forward and reverse RF signal power level data is an average value of a predetermined interval of the forward and reverse digital signals continuously inputted, The main hub unit and the remote optical unit are provided with a downconversion module and an upconversion module, and gain control for these downconversion module and upconversion module is not performed. And the device for measuring the power level of the RF signal is not used in the main hub unit and the remote optical unit. delete A digital hub processing method in a digital optical relay system comprising a main hub unit for wireless communication with a base station, and a remote optical unit connected to the main hub unit via an optical cable and wirelessly communicating with a subscriber station, At the remote optical unit, signal processing forward and reverse digital signals to detect forward and reverse RF signal power level data from an input digital signal; Searching for gain adjustment data corresponding to the detected forward and reverse RF signal power level data in a forward and backward gain adjustment information table; And adjusting the gain of the forward and reverse RF signals digitally by numerically calculating the gain control data for the found forward and reverse RF signals to the input forward and reverse digital signals. The forward and reverse RF signal power level data are averaged for a predetermined period of the digital signal of the forward and reverse direction input continuously, digital signal processing method in a digital optical relay system.

Images