JP2000059654A - Two-way digital signal transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain long distance transmission of a digital signal by placing two transmission sections that send/receive a signal to both ends of a transmission line and converting the signal into an optical signal and converting the optical signal into the electric signal and transmitting the converted signal from the two transmission sections to the transmission line. SOLUTION: This device has a transmission line and two transmission section 1, 3 that connect to both ends of the transmission line to transmit/receive a signal, a video signal and an audio signal or the like received by the transmission section 1, 3 are time division multiplexed and time base compressed as digital signals and the compressed signal is transmitted as the signal. The device has the transmission line consisting of coaxial cables 2-1, 2-2 through which an electric signal is transmitted, repeater 4-1, 4-2 that convert the electric signal into the optical signal and convert the optical signal into the electric signal, and an optical fiber cable 5 through which the optical signal is transmitted. Then the signal is converted from the electric signal into the optical signal and form the optical signal into the electric signal, then transmitted from the transmission sections 1, 3 to the transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable connected to a repeater for performing optical transmission in the middle of a transmission line using a coaxial cable, and a video signal of a digital signal from a transmission section provided at both ends of the transmission line. The present invention relates to a bidirectional digital signal transmission device capable of transmitting audio signals, control signals, and the like bidirectionally over long distances.

[0002]

2. Description of the Related Art Generally, a television camera apparatus used for broadcasting is roughly divided into a camera head for photoelectrically converting a subject optical image incident from an imaging lens into a video signal, amplifying the video signal, and outputting a video signal of a predetermined level. And a camera control unit (CCU: Camera Control Unit) that performs various signal processing on a video signal input from the camera head unit, outputs a predetermined video signal to other devices, and remotely controls required functions of the camera head unit. Control Unit). In such a television camera device, a bidirectional signal transmission device is provided between the camera head unit and the camera control unit, and the camera head unit transmits a video signal that has been photoelectrically converted and amplified by the camera head unit. Signals and audio signals collected by the microphone are transmitted using a transmission cable.On the other hand, a video signal for monitoring with the viewfinder of the camera head section and audio for communication are transmitted from the camera control section to the camera head section. Signals, required control signals for controlling the camera head, and the like are transmitted using the transmission cable.

[0003] These video signals, audio signals, control signals and the like are transmitted using a transmission cable having a triple coaxial cable called a triax cable between the camera head unit and the camera control unit. However, coaxial cables have a limited transmission band, and together with video signals with a wide frequency band, audio signals,
In order to transmit a control signal or the like, it must be multiplexed and transmitted by a bidirectional signal transmission device. In the conventional multiplex transmission, a carrier having a predetermined frequency is modulated by a video signal, an audio signal, a control signal, or the like of an analog signal, and frequency-division multiplexing is performed to perform bidirectional transmission. As a recent example, a camera head unit and a camera control unit connected by a single coaxial cable convert analog video signals, audio signals, and the like into digital signals, and convert digital video signals, audio signals, and the like. By performing time division multiplexing and time axis compression to create a transmission signal consisting of repetition of a signal period and a no-signal period, and transmitting a transmission signal from the other during a non-signal period of the transmission signal from one, 1 "Digital Video Signal Multiplexing Transmission Method and Apparatus" for enabling bidirectional transmission with a single coaxial cable (Japanese Patent Laid-Open No. 7-203)
399).

FIG. 3 shows a configuration example of a transmission apparatus which digitizes the video signal and audio signal to be transmitted and time-division multiplexes between the camera head unit and the camera control unit and transmits the signal in both directions. Figure 5 shows the form of the transmitted signal.
Shown in A transmission unit 31 provided on the camera head unit side of the conventional bidirectional digital signal transmission device converts analog luminance signal Y, color signal Pb, color signal Pr, audio signal A1, etc. into respective A / D converters 31. -1 and converted into digital signals by the respective A / D converters 31-1 and output to the multiplexer 31-2. The multiplexer 31-2 outputs a luminance signal Y, a chrominance signal Pb, and a chrominance signal Pr of the digital signal input from each A / D converter 31-1.
The audio signal A1 and the like are multiplexed, and the multiplexed signal 3a is output to the time axis compressor 31-3. The time axis compressor 31-3 is
The time axis of the multiplexed signal 3a input from the multiplexer 31-2 is compressed, and a repetitive signal having a signal period and a non-signal period (camera head unit side transmission data shown in FIG. 5A) is obtained. An intermittent compressed signal 3b which repeats a signal period and a non-signal period is transmitted to the coaxial cable 32 via the line interface 31-4.

[0005] A compressed signal 3b which repeats a signal period and a non-signal period transmitted from the camera head unit and transmitted through the coaxial cable 32 is received by a transmission unit 33 provided on the camera control unit side. The compressed signal 3b that repeats the signal period and the no-signal period received by the transmission unit 33 is input to the decompressor 33-2 via the line interface 33-1. The decompressor 33-2 outputs a compressed signal 3 that repeats a signal period and a non-signal period input via the line interface 33-1.
The multiplexed signal 3a is output to the demultiplexer 33-3 as the original multiplexed signal 3a obtained by extending the time axis of b. Separator 33-
Reference numeral 3 denotes a multiplexed signal 3a input from the decompressor 33-2, which is a digital signal of a luminance signal Y, a chrominance signal Pb, and a chrominance signal P.
r, audio signals A1, etc., and output to the respective D / A converters 33-4. Each D / A converter 33-
Reference numeral 4 converts the luminance signal Y, color signal Pb, color signal Pr, audio signal A1, and the like of the digital signals input from the separator 33-3 into analog signals, and outputs the analog signals to a predetermined circuit of the camera control unit.

On the other hand, a transmission section 33 provided on the camera control section side includes an analog return video signal M input from a predetermined circuit of the camera control section and an audio signal A for communication.
2 and the like are input to the respective A / D converters 33-5, converted into digital signals by the respective A / D converters 33-5, and output to the multiplexer 33-6. The multiplexer 33-6 multiplexes the return video signal M of the digital signal input from each A / D converter 33-5 and the audio signal A2 for communication and the like, and multiplexes the multiplexed signal 3c into the compressor 3-3.
Output to 3-7. The compressor 33-7 includes a multiplexer 33-.
6 to compress the data of the multiplexed signal 3c, and output the data compressed signal to the compressor 33-8. Compressor 33
-8 compresses the time axis of the data compression signal 3d input from the compressor 33-7, and outputs a repetition signal having a signal period and a non-signal period (the transmission data on the camera control unit side shown in FIG. 5B). ), And the intermittent compressed signal 3e which repeats a signal period and a non-signal period is transmitted to the line interface 33-1.
Through the coaxial cable 32. The compressed signal 3e which repeats a signal period and a non-signal period sent from the line interface 33-1 to the coaxial cable 32 is a signal transmitted from the line interface 31-4 on the camera head side to the coaxial cable 32. So that the compressed signal 3b repeats the period and the no-signal period,
The signal is transmitted to the coaxial cable 32 (see FIG. 5).

A compressed signal 3e, which repeats a signal period and a non-signal period transmitted through the coaxial cable 32, is received by a transmission unit 31 provided on the camera head unit side. Transmission unit 3
The compressed signal 3e which repeats the signal period and the non-signal period received in 1 is input to the decompressor 31-5 via the line interface 31-4. The expander 31-5 expands the time axis of the compressed signal 3e, which repeats a signal period and a no-signal period, input via the line interface 31-4, to obtain the original multiplexed signal 3c, and the multiplexed signal 3c To the separator 31-6
Output to The demultiplexer 31-6 demultiplexes the multiplexed signal 3c input from the decompressor 31-5 into a digital return video signal M and an audio signal A2 for communication and the like, and the respective D / A converters 31-31. 7 is output. Each D
The / A converter 31-7 converts the return video signal M of the digital signal input from the separator 31-6 and the audio signal A2 for communication and the like into analog signals, respectively, and sends them to a predetermined circuit of the camera head unit. Output.

Here, the line interface 31-
4 and 33-1 are shown in FIG. (The same line interface can be used for the line interfaces 31-4 and 33-1.) The line interface 3 of the transmission unit 31 on the camera head unit side
1-4 sends out a compressed signal 3b which repeats a signal period and a non-signal period inputted from the time axis compressor 31-3, to the transmission amplifier 5;
4, the signal is amplified to a required level, selected by the interface 53, and the compressed signal 3b is transmitted to the camera control unit-side transmission unit 33 via the coaxial cable 32 only during the signal period. The compressed signal 3e transmitted via the cable 32 is selected by the interface 53, and the compressed signal 3b from the time base compressor 31-3 is input to the receiving amplifier 55 during the non-signal period, and the receiving amplifier 55 reaches the required level. The signal is amplified, and the distortion generated due to the length and the cable characteristics of the coaxial cable 32 is compensated for by the equalizing amplifier 56 and output to the expander 31-5.

Similarly, the line interface 33-1 of the camera controller-side transmission unit 33 transmits the compressed signal 3e, which repeats the signal period and the no-signal period, input from the compressor 33-8 to the required level by the transmission amplifier 54. Amplify and interface 5
3, the compressed signal 3e is transmitted to the camera head unit side transmission unit 31 via the coaxial cable 32 only during the signal period, and is transmitted from the camera head unit side transmission unit 31 via the coaxial cable 32. The compressed signal 3b is sorted by the interface 53 and the compressed signal 3b from the compressor 33-8 is selected.
e is input to the receiving amplifier 55 during the no-signal period, and is amplified to a required level by the receiving amplifier 55.
In step 6, the distortion generated due to the length and the cable characteristics of the coaxial cable 32 is compensated and output to the expander 33-2. Thus, the line interfaces 31-4 and 3-4
3-1 is the coaxial cable 32 and the transmission unit 31 or 33
Interface with the compressed signal 3b or 3e
Input / output selection, amplification, and distortion compensation.

As described above, the conventional bidirectional digital signal transmission apparatus includes a camera head side transmission data such as a video signal and an audio signal transmitted from the camera head side to the camera control side, and a camera control section side. As shown in FIG. 5, video signals, audio signals, control signals, and other data transmitted from the camera control unit to the camera head unit have required times and occupy different times. Since the data is transmitted bidirectionally on the coaxial cable, bidirectional transmission without mutual interference can be performed with one coaxial cable. However, when video signals and audio signals are digitized and time-division multiplexed, the bit rate becomes extremely high. For example, the luminance signal Y of the video signal transmitted from the camera head side is 13.5M.
Hz, two types of color signals Pb and Pr are sampled at 6.75 MHz and quantized with 10 bits, and the total bit rate is 270 Mbps (｛13.5+ (6.75 ×
2)｝ × 10) In addition, since the video signal transmitted from the camera control unit can be tolerated even if there is some deterioration in image quality, for example, even if a video signal compressed to 1/5 is assumed, its bit rate is 54 Mbps (270 Mbps).
÷ 5). When several channels of audio signals are added to these video signals, the total bit rate becomes 330 Mb.
ps.

When such high-speed digital data is transmitted through a coaxial cable, the loss in the coaxial cable is large, and the length (distance) of the coaxial cable that can be transmitted is limited. This depends on the method of compensating the loss in the coaxial cable, but the transmission distance is about 300 meters. In signal transmission between the camera head unit and the camera control unit, in general, it is acceptable if a distance of about 300 meters can be transmitted. However, in order to expand the use of the television camera system, the transmission distance is greatly increased. Will be an issue. High-speed, low-loss transmission of digital data can be generally realized by using an optical fiber cable. In particular, in the case of a television camera system, a coaxial cable already laid in a studio or a field (for example, a golf course) is used. In many cases, the camera head and the camera controller must be connected directly with an optical fiber cable.
There are problems such as laying work.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problem, the present invention provides a transmission device for transmitting a digitized transmission signal in both directions by connecting a transmission line to one transmission unit with a coaxial cable connected to one transmission unit. Between the two coaxial cables connected to the transmission unit, two transponders connected between the two coaxial cables and converting an electric signal to an optical signal and converting an optical signal to an electric signal, It is an object of the present invention to provide a bidirectional digital signal transmission apparatus which is capable of transmitting digitalized transmission signals over a long distance by using a transmission path connected to an optical fiber cable for transmitting high-speed digital data with little cable loss.

[0013]

To achieve the above object, a bidirectional digital signal transmission device according to the present invention comprises a transmission line for transmitting a transmission signal in both directions, and a transmission line connected to both ends of the transmission line. It has two transmission units for transmitting and receiving a transmission signal, and compresses time-division multiplexed and time-axis compressed video signals, audio signals, control signals, and the like input to the two transmission units as digital signals. In a bidirectional digital signal transmission device for transmitting a signal as the transmission signal, a coaxial cable for transmitting an electric signal, a repeater for converting an electric signal to an optical signal, and converting an optical signal to an electric signal, and transmitting the optical signal And the transmission signal transmitted from the two transmission units to the transmission line, from an electrical signal to an optical signal, further from an optical signal to an electrical signal. It is obtained so as to transmit and conversion.

A two-way digital signal transmission device according to the present invention includes a transmission line for transmitting a transmission signal in two directions and two transmission units connected to both ends of the transmission line for transmitting and receiving the transmission signal. A video signal, an audio signal, a control signal, and the like input to the two transmission units are converted into digital signals by time-division multiplexing, time-axis compression, and a compressed signal that repeats a signal period and a no-signal period. And the transmission signal transmitted from another transmission unit to the transmission line during a non-signal period of the transmission signal transmitted from one transmission unit to the transmission line. In the bidirectional digital signal transmission device for transmitting the transmission signal transmitted from one transmission unit to the transmission line during a non-signal period of the transmission signal transmitted from the two transmission units to the transmission line, the electric signal is transmitted. A transmission line comprising a coaxial cable, an optical signal to an optical signal, an optical signal to an optical signal, and a fiber optic cable to transmit the optical signal. And converting the transmission signal transmitted from the transmission line to the transmission path from an electric signal to an optical signal and further from an optical signal to an electric signal.

More specifically, in the bidirectional digital signal transmission device of the present invention, the transmission path includes a first coaxial cable for transmitting an electric signal, an electric signal converted to an optical signal,
A first repeater for converting an optical signal into an electric signal, a composite optical fiber cable including two optical fiber cables,
A second repeater for converting an electric signal to an optical signal and an optical signal to an electric signal, and a second coaxial cable for transmitting the electric signal, wherein the first coaxial cable and the first repeater Transmitting a transmission signal on the transmission line connected to the first repeater and the composite optical fiber cable, the composite optical fiber cable and the second repeater, the second repeater and the second coaxial cable,
The present invention converts an electric signal into an optical signal and further converts an optical signal into an electric signal and transmits the converted signal. Further, the bidirectional digital signal transmission device of the present invention includes a relay, an interface for selecting an input electric signal and an output electric signal, and an equalizing amplifier for compensating for transmission distortion of the input electric signal. An electrical signal / optical signal converter that converts an electrical signal compensated for transmission distortion into an optical signal and outputs the optical signal to an optical cable;
An optical signal / electric signal converter for converting an optical signal input from an optical cable into an electric signal.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the bidirectional digital signal transmission device according to the present invention will be described. FIG. 1 is a block diagram of a bidirectional digital signal transmission device according to the present invention. The bidirectional digital signal transmission device of the present invention is a device connected between a camera head unit and a camera control unit of a television camera system, and includes a transmission unit, a transmission path, and a camera control unit-side transmission unit. It is a device that includes a transmission unit and bidirectionally transmits a video signal, an audio signal, a control signal, and the like over a long distance. In FIG. 1, the connected camera head and camera control unit are omitted.

In FIG. 1, reference numeral 1 denotes a transmission unit on the camera head unit side, and 1-1 denotes an analog luminance signal Y, color signal Pb, color signal Pr, and audio signal A input from the camera head unit.
Each of the A / D converters for converting 1 and the like into a digital signal, and 1-2 are a luminance signal Y, a color signal Pb, and a color signal P
r, a multiplexer that multiplexes the audio signal A1 and the like and outputs a multiplexed signal 1a, 1-3 compresses the time axis of the multiplexed signal 1a input from the multiplexer 1-2, A time axis compressor that outputs a repetitive signal having a no-signal period (transmitted data on the camera head unit side shown in FIG. 5A) and outputs an intermittent compressed signal 1b that repeats a signal period and a no-signal period; 4 transmits the amplified compressed signal 1b to the transmission unit 1
And a line interface for receiving and amplifying the compressed signal 1e from the transmission line while extending the time axis of the received compressed signal 1e input from the line interface 1-4. The decompressor 1-6 outputs the multiplexed signal 1c input from the decompressor 1-5 into an original digital signal return video signal M and an audio signal A2 for communication or the like. A separator 1-7 for converting the digital signal input from the separator 1-6 into a video signal M for returning the original analog signal and an audio signal A2 for communication and the like; 2-
1 and 2-2 are coaxial cables constituting a transmission line;
Reference numerals 1 and 4-2 denote repeaters constituting a transmission path, reference numeral 5 denotes an optical fiber cable constituting a transmission path, reference numeral 3 denotes a transmission section on the camera control section side, and reference numeral 3-1 denotes an amplified compressed signal 1d from the transmission section 3. The line interface 3-2 for transmitting the signal to the transmission line and receiving and amplifying the compressed signal 1b from the transmission line 3-2 extends the time axis of the received compressed signal 1b input from the line interface 3-1. The decompressor 3-3 outputs the multiplexed signal 1a as the multiplexed signal 1a, and outputs the luminance signal Y of the digital signal based on the multiplexed signal 1a input from the decompressor 3-2.
The separator 3-4 separates the color signal Pb, the color signal Pr, the audio signal A1, etc., from the digital signal input from the separator 3-3.
b, a D / A converter for converting a color signal Pr, an audio signal A1 and the like, and a digital signal 3-5 for sending back the analog video signal M input from the camera control unit and the audio signal A2 for communication and the like. A / D converters 3-6 multiplex and multiplex the return video signal M of the digital signal input from each A / D converter 3-5 and the audio signal A2 for communication and the like. A multiplexer for outputting the signal 1c, a compressor 3-7 for compressing the data of the multiplexed signal 1c input from the multiplexer 3-6 and outputting a data compression signal 1d, and a compressor 3-8 for the signal 3c 3-7, the time axis of the compressed data signal 1d is compressed, and a repetition signal having a signal period and a non-signal period (camera control unit-side transmission data shown in FIG. 5B). Intermittent with repeated periods of no signal Shows a compressor to output a reduced signal 1e.

The operation will be described below. The bidirectional digital signal transmission device of the present invention transmits a luminance signal Y and a color signal Pb, which are components of a video signal of a captured subject, from a camera head unit (not shown) to the transmission unit 1 on the camera head unit side.
The color signal Pr and the audio signal A1 collected by the microphone are converted into digital luminance signal Y, color signal Pb, color signal Pr, audio signal A1, etc. by the respective A / D converters 1-1. Output to 1-2. Multiplexer 1-
2 multiplexes a luminance signal Y, a chrominance signal Pb, a chrominance signal Pr, an audio signal A1 and the like of a digital signal input from each A / D converter 1-1 into a multiplexed signal 1a, and a time axis compressor. Output to 1-3. The time axis compressor 1-3 compresses the multiplexed signal 1a input from the multiplexer 1-2 on the time axis, and also includes a repetitive signal having a signal period and a non-signal period (the camera shown in FIG. 5A). The intermittent compressed signal 1b, which repeats a signal period and a no-signal period, is transmitted to the transmission line via the line interface 1-4.

The transmission path includes a coaxial cable 2 and a repeater 4
And the optical fiber cable 5. Since the transmission signals from the camera head unit-side transmission unit 1 and the camera control unit-side transmission unit 3 are transmitted to the coaxial cable 2, they are connected to the coaxial cable 2. The repeater 4 and the optical fiber cable 5 must receive, compensate, and transmit bidirectional transmission signals. The transmission path is composed of a coaxial cable 2-1, a repeater 4-1 and a composite optical fiber cable 5 composed of two optical fiber cables, a repeater 4-2, and a coaxial cable 2-2. . FIG. 2 shows a block diagram of the repeater 4, but the two repeaters 4-1 and 4-2 have the same configuration. 2, reference numeral 21 denotes transmission units 1 and 3 via a coaxial cable 2.
A terminal for inputting / outputting an electric signal (compressed signal) from the terminal; 22, an interface circuit for selecting input / output signals; 23, a length and cable characteristics of the coaxial cable 2 of the electric signal transmitted via the coaxial cable 2 The equalizing amplifier 24 for compensating for the distortion generated due to the electric signal, converts the electric signal whose distortion has been compensated for by the equalizing amplifier 23 into an optical signal /
The optical signal conversion circuit 25 is an electric signal / optical signal conversion circuit 2
4 is a terminal to which an optical signal is output from the other repeater 4 to the other repeater 4 via the optical fiber cable 5; 27 is a terminal to which an optical signal is input from the other repeater 4 via the optical fiber cable 5;
Reference numeral 6 denotes an optical signal / electric signal conversion circuit that converts an optical signal input from the optical signal input terminal 27 into an electric signal.

The coaxial cable 2-1 constituting the transmission path is
A compressed signal 1b, which repeats a signal period and a no-signal period, input from the transmission unit 1 on the camera head unit side is transmitted, and a compressed signal 1b that repeats the transmitted signal period and a no-signal period is output to the repeater 4-1. I do. The repeater 4-1 is a coaxial cable 2-
1 is an equalizing amplifier that converts a loss when the signal is transmitted through the coaxial cable 2-1 into a compressed signal 1b which is input through the input / output terminal 21 through the input / output terminal 21 and repeats a signal period and a non-signal period selected by the interface circuit 22. After compensating and amplifying at 23, it is converted into an optical signal by an electric signal / optical signal conversion circuit 24,
The converted optical signal is transmitted to one optical fiber cable in the composite optical fiber cable 5 via the optical signal output terminal 25. One optical fiber cable in the composite optical fiber cable 5 transmits the optical signal transmitted from the repeater 4-1 and transmits the transmitted optical signal to the repeater 4-2. The repeater 4-2 converts an optical signal input from one optical fiber cable in the composite optical fiber cable 5 via the optical signal input terminal 27 into a signal period and a non-signal period by the optical signal / electrical signal conversion circuit 26. Is converted into a compressed signal 1b which repeats the above, the compressed signal 1b which repeats the converted signal period and the non-signal period is selected by the interface circuit 22 and output to the coaxial cable 2-2 via the input / output terminal 21. The coaxial cable 2-2 transmits a compressed signal 1b that repeats a signal period and a no-signal period input from the repeater 4-2, and converts the compressed signal 1b that repeats the transmitted signal period and a no-signal period into a camera control unit. Output to the transmission section 3 on the side of the side.

The compressed signal 1b which repeats a signal period and a non-signal period transmitted from the transmission unit 1 on the camera head unit side and transmitted through a transmission line including a coaxial cable, a repeater, and an optical fiber cable is transmitted to the camera control unit. It is received by the transmission unit 3 provided on the side. The compressed signal 1b that repeats the signal period and the no-signal period received by the transmission unit 3 is input to the decompressor 3-2 via the line interface 3-1. Stretcher 3
-2 is the original multiplexed signal 1a obtained by expanding the time axis of the compressed signal 1b that repeats a signal period and a non-signal period input via the line interface 3-1;
Is output to the separator 3-3. The separator 3-3 includes the expander 3
-2 are separated into a luminance signal Y, a chrominance signal Pb, a chrominance signal Pr, an audio signal A1 and the like of digital signals, and output to the respective D / A converters 3-4. Each of the D / A converters 3-4 outputs a luminance signal Y and a chrominance signal P of the digital signal input from the separator 3-3.
b, the color signal Pr, the audio signal A1, etc., are respectively converted into analog luminance signal Y, color signal Pb, color signal Pr, audio signal A1, etc., and output to a predetermined circuit of the camera control unit. Note that the line interfaces 1-4 and 3-
1 is a block diagram shown in FIG. 4, which is the same as the line interface used in the description of the prior art, and includes an interface 53, a transmitting amplifier 54, a receiving amplifier 55, and an equalizing amplifier 5.
6 and the operation is the same, so a detailed description is omitted.

On the other hand, the transmission section 3 provided on the camera control section side includes a return video signal M of an analog signal input from a predetermined circuit of the camera control section and an audio signal A for communication and the like.
2 and the like are input to the respective A / D converters 3-5, and are converted into the return video signals M of digital signals and the audio signals A2 for communication and the like by the respective A / D converters 3-5. Output to multiplexer 3-6. Multiplexer 3-
Reference numeral 6 multiplexes the return video signal M of the digital signal input from each A / D converter 3-5 and the audio signal A2 for communication or the like, and outputs the multiplexed signal 1c to the compressor 3-7. The compressor 3-7 compresses the data of the multiplexed signal 1c input from the multiplexer 3-6, and outputs a data compressed signal 1d to the compressor 3-8. The compressor 3-8 includes a compressor 3-8.
7, the time axis of the data compression signal 1d input from the camera 7 is compressed, and a repetition signal having a signal period and a non-signal period (transmitted data on the camera control unit side shown in FIG. 5B) is formed. The compressed signal 1e repeating the period is transmitted to the transmission line via the line interface 3-1. The compressed signal 1e which repeats a signal period transmitted from the line interface 3-1 to the transmission line and a non-signal period is a signal period in which the signal period transmitted from the line interface 1-4 on the camera head side to the transmission line and the non-signal period The compressed signal 1b is sent to the transmission line during the non-signal period of the compressed signal 1b (see FIG. 4).

The coaxial cable 2-2 constituting the transmission path is
The repeater 4 transmits a compressed signal 1e that repeats a signal period and a non-signal period input from the transmission unit 3 on the camera control unit side and repeats the transmitted signal period and a non-signal period.
-2. The repeater 4-2 is a coaxial cable 2-2.
From the coaxial cable 2-2 generated in the compressed signal 1e which repeats a signal period and a non-signal period which are input from the interface circuit 22 via the input / output terminal 21 and which are selected by the interface circuit 22, and reduce the loss. After compensating and amplifying at 23, it is converted into an optical signal by an electric signal / optical signal conversion circuit 24,
The converted optical signal is output to another optical fiber cable in the composite optical fiber cable 5 via the optical signal output terminal 25. Another optical fiber cable in the composite optical fiber cable 5 transmits the optical signal transmitted from the repeater 4-2, and transmits the transmitted optical signal to the repeater 4-1. The repeater 4-1 is connected to the optical signal input terminal 27 from another optical fiber cable in the composite optical fiber cable 5.
The optical signal input through the optical signal / electrical signal conversion circuit 2
6, the signal period and the non-signal period are converted into a compressed signal 1e which repeats the signal period and the non-signal period.
1 to the coaxial cable 2-1. The coaxial cable 2-1 transmits a compressed signal 1e that repeats a signal period and a non-signal period received from the repeater 4-1 and transmits a compressed signal 1e that repeats the transmitted signal period and a non-signal period to a camera head unit. To the transmission unit 1 on the side.

A compressed signal 1e, which repeats a signal period and a non-signal period transmitted through the transmission path, is received by the transmission unit 1 provided on the camera head unit side. The compressed signal 1e, which repeats a signal period and a non-signal period, received by the transmission unit 1, is input to the decompressor 1-5 via the line interface 1-4. The decompressor 1-5 decompresses the time axis of the compressed signal 1e, which repeats a signal period and a non-signal period input via the line interface 1-4, into the original multiplexed signal 1c, and the multiplexed signal 1c Is output to the separator 1-6. Separator 1-6
The multiplexed signal 1c input from the decompressor 1-5 is combined with the return signal M of the digital signal and the audio signal A2 for communication etc.
And output to each D / A converter 1-7. Each of the D / A converters 1-7 converts the return signal M of the digital signal input from the separator 1-6 and the audio signal A2 for communication or the like into the return signal M of an analog signal and the audio for communication or the like, respectively. The signal is converted into a signal A2 or the like and output to a predetermined circuit of the camera head unit.

As described above, the bidirectional digital signal transmission apparatus of the present invention does not require any change in the interface between the conventionally used triax cable and the input / output signals of the television camera and camera control unit. It is not necessary, and an optical fiber cable with low transmission loss can be connected in the middle, and when transmitting video signals, audio signals, control signals, etc. bidirectionally with one cable, the cable length can be easily extended. The transmission distance can be greatly extended.

[0026]

According to the present invention, a video signal, an audio signal,
In a system for transmitting control signals and the like bidirectionally between a camera head unit and a camera control unit via a coaxial cable, an electric signal is converted into an optical signal in the middle of the coaxial cable, and
Using two relay means to convert the optical signal into an electric signal,
Provided is a bidirectional digital signal transmission device which can use an optical fiber cable capable of transmitting high-speed digital data between two relay means with a small cable loss, and can extend a transmittable distance. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a bidirectional digital signal transmission device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a repeater constituting a transmission line of the bidirectional digital signal transmission device of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional bidirectional digital signal transmission device.

FIG. 4 is a diagram showing a form of a signal transmitted through a transmission line in the bidirectional digital signal transmission device.

FIG. 5 is a block diagram showing a configuration of a line interface constituting a transmission unit of the bidirectional digital signal transmission device.

[Explanation of symbols]

1, 31: Camera head side transmission section, 2, 32: Coaxial cable, 3, 33: Camera control section transmission section, 4: Repeater, 5: Composite optical fiber cable, 1-1, 3-5 , 3
1-1, 33-5... A / D converters, 1-2, 3-6, 3
1-2, 33-6: Multiplexer, 1-3, 31-3: Time axis compressor, 1-4, 3-1, 31-4, 33-1: Line interface, 1-5, 3- 2, 31-5, 33-2
... Expander, 1-6, 3-3, 31-6, 33-3 ... Separator, 1-7, 3-4, 31-7, 33-4 ... D / A converter, 3-7,3 -8, 33-7, 33-8 ... Compressor, 2
2 Interface, 23 Equalization amplifier, 24 Electric /
Optical converter, 26 ... optical / electrical converter, 54 ... transmission amplifier,
55: receiving amplifier, 56: equalizing amplifier. 1a, 1c, 3
a, 3c: multiplexed signal, 1b, 1e, 3b, 3e: compressed signal, 1d, 3d: data compressed signal.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 5/16 H04B 9/00 J // H04N 7/08 H04N 7/08 Z 7/081 7/173 F Terms (reference) 5C022 AB00 AB65 AC42 AC69 AC75 5C063 AB03 AB06 AB09 AC01 AC05 AC10 DA07 5C064 BA07 BB03 BC10 BD16 5K002 AA05 AA06 CA01 DA04 DA05 FA01 GA01 GA02 GA04 5K018 AA03 BA03 CA06 DA02 DA06 DA12 JA02

Claims (4)

[Claims] 1. A transmission line for transmitting a transmission signal in both directions, and two transmission units connected to both ends of the transmission line for transmitting and receiving the transmission signal. Video signals, audio signals, control signals, etc. to be input are converted into digital signals and time-division multiplexed.
In a bidirectional digital signal transmission device for transmitting a compressed signal compressed on a time axis as the transmission signal, a coaxial cable for transmitting an electric signal, a repeater for converting the electric signal to an optical signal, and converting the optical signal to an electric signal. An optical fiber cable for transmitting an optical signal, the transmission path comprising: transmitting the transmission signal from the two transmission units to the transmission path from an electrical signal to an optical signal; A bidirectional digital signal transmission device characterized by being converted into a signal and transmitted. 2. A transmission line for transmitting a transmission signal in both directions, and two transmission units connected to both ends of the transmission line for transmitting and receiving the transmission signal. Video signals, audio signals, control signals, etc. to be input are converted into digital signals and time-division multiplexed.
The transmission signal is composed of a compressed signal that is time-axis-compressed and repeats a signal period and a no-signal period, and the other transmission signal is transmitted from one transmission unit to the transmission path during another non-signal period of the transmission signal.
The transmission signal transmitted from one of the transmission units to the transmission line, and the transmission signal transmitted from one of the transmission units to the transmission line during a non-signal period of the transmission signal transmitted from the other one of the transmission units to the transmission line. A bidirectional digital signal transmission device for transmitting the transmission signal to be transmitted, comprising: a coaxial cable for transmitting an electric signal; a repeater for converting the electric signal to an optical signal, and a light signal to an electric signal; The transmission path configured from the two transmission units to the transmission path, an electric signal to an optical signal, and further from an optical signal to an electric signal. A bidirectional digital signal transmission device, characterized in that the transmission is performed by transmitting a digital signal. 3. The bidirectional digital signal transmission device according to claim 1, wherein the transmission path comprises: a first coaxial cable for transmitting an electric signal;
A first repeater for converting an electrical signal to an optical signal and an optical signal to an electrical signal, a composite optical fiber cable composed of two optical fiber cables, an electrical signal to an optical signal, and an optical signal to an optical signal; A first coaxial cable and a first repeater, a first repeater and a composite optical fiber cable, comprising a second repeater for converting to an electric signal, and a second coaxial cable for transmitting the electric signal; Composite optical fiber cable and second
The transmission line connected to the second repeater and the second repeater and the second coaxial cable converts the transmission signal from an electric signal to an optical signal and further converts the optical signal to an electric signal and transmits the signal. A bidirectional digital signal transmission device, characterized in that: 4. The bidirectional digital signal transmission device according to claim 1, wherein the repeater has an interface for selecting an input electric signal and an output electric signal. An equalizing amplifier for compensating the transmission distortion of the electric signal, and an electric signal for converting the electric signal compensated for the transmission distortion into an optical signal and outputting the same to an optical cable.
A bidirectional digital signal transmission device comprising: an optical signal converter; and an optical signal / electrical signal converter that converts an optical signal input from an optical cable into an electric signal.