JP4445233B2 - Transmission equipment - Google Patents

Description

  The present invention relates to a transmission apparatus, and more particularly to a transmission apparatus for an STL system that transmits a digital signal between a studio and a transmitting station in a television station.

  In television broadcasting, a video signal of a program produced in a studio of a television station is sent to a transmitting station located at a high place such as a mountain peak and transmitted to each home as a high-frequency radio wave. A transmission system that connects between the studio and the transmitter is generally called an STL system. The function of the STL system is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-285154 (Patent Document 1).

  The STL system is an important line for delivering TV radio waves to ordinary households. For example, in the case of a failure, the studio side device converts the modulation output into microwaves in the transmission control unit for modulating the video signal. A dual circuit configuration is provided in which two high-frequency units for transmission and a transmission circuit system including a power source and the like are prepared.

A basic configuration of a duplexed STL system is shown in FIG. 6 is a transmitting antenna on the studio side, and 7 is a receiving antenna on the transmitting station side.
The video signal recorded in the studio becomes a digital video signal (video data) and is input to the two systems of transmission control units 1 (1a, 1b). Each transmission control unit periodically inserts a preamble pattern into a digital video signal, performs single 64QAM modulation, and then outputs it as a 130 MHz broadcast IF (Intermediated Frequency) signal (IF-a, IF-b). The preamble pattern is used on the receiving side to determine the sampling timing of the subsequent data symbol and to correct waveform distortion that occurs during transmission.

  The IF signal output from each transmission control unit 1 is input to the transmission high-frequency unit 2 (2a, 2b) via the main signal line 50 (50a, 50b), and further frequency-converted into a high-frequency microwave band signal. After that, the power is amplified and output. Output signals of the transmission high-frequency units 2 a and 2 b are input to the output selection switch 5, and one of them is selectively output to the transmission antenna 6. The output selection switch 5 selects one of the two systems of power amplification outputs according to the switching control signal SEL5 output from the switching control unit 3 to the signal line 53. The switching control unit 3 receives the state information AL (AL1a to AL2b) from each of the duplexed transmission control units 1 and the transmission high frequency unit 2 via the signal lines 51a to 52b, and outputs the transmission circuit system output during normal operation. A switching control signal SEL5 is generated so as to be supplied to the transmission antenna 6.

  Usually, the transmission antenna 6 on the studio side is attached to a steel tower portion installed on the roof portion of the TV station building. Further, since the frequency band of the output signal of the transmission high-frequency unit 2 is a microwave, if the wiring distance between the transmission high-frequency unit 2 and the transmission antenna 6 is long, a significant loss in transmission power occurs. For this reason, generally, each transmission high frequency part 2 (2a, 2b) is arrange | positioned in the rooftop building (penthouse 21) near the steel tower for antennas, as shown in the figure, and the transmission control part 1 (1a, 1b) is arranged in a studio building where the video data signal is generated or in a machinery storage room (rack room 20) in the vicinity thereof.

  As described above, in the STL system on the studio side, a long connection cable (signal line) of, for example, 100 m or more is provided between the transmission control unit 1 disposed in the rack room 20 and the transmission high-frequency unit 2 disposed in the penthouse 21. 50a, 50b). Similarly, between the switching control unit 3 in the rack chamber 20 and the transmission high-frequency unit 2 in the penthouse 21, the state information AL and the switching control signal SEL5 are transmitted via long connection cables (52a, 52b, 53). It will be sent and received.

  A microwave single QAM signal transmitted from the transmitting antenna 6 on the studio side is received by a single QAM receiving antenna 7 of a transmitting station (master station) located on the mountaintop several kilometers to several tens of kilometers away. The single QAM signal received by the antenna 7 is branched into two systems by the distributor 8 and input to the reception high frequency units 9a and 9b. Each reception high-frequency unit 9 (9a, 9b) converts the received single QAM signal into IF signals (IF-A, IF-B) of around 130 MHz and outputs them to the main signal lines 60a, 60b. The reception control units 10 (10a, 10b) connected to the main signal lines 60a, 60b demodulate the video data from these IF signals (IF-A, IF-B) and output them to the output selection switch 11.

  The output selection switch 11 is controlled by a control signal SEL11 from the switching control unit 13, and the demodulated video data selected by the output selection switch 11 is used for a high-power transmitter for broadcasting (not shown) or a TTL (Transmitter Transmitter Link). Supplied to the transmitter. Broadcast radio waves for general households are transmitted from the high power transmitter. The switching control unit 13 receives status information from each of the duplex reception high-frequency units 9 and the reception control unit 10 via the signal lines 61a to 62b as in the studio side, and outputs the reception circuit system that is operating normally. The output selection switch 11 is controlled so that the signal is input to the high power transmission apparatus.

JP 2001-285154 A

  As described above, in the STL system, the transmission control unit 1 installed in the studio-side rack room 20 and the transmission high-frequency unit 2 installed in the penthouse 21 are very far apart. Therefore, between the rack room and the penthouse, two main signal lines 50a and 50b, signal lines 52a and 52b for the switching control unit 3 to collect state information of the penthouse side, and the output selection switch 5 If the control signal line 53 for controlling is to be wired, it is necessary to lay a large number of cables over a long distance, and there is a problem that wiring work takes time and high member costs are required. A similar problem occurs in the STL system on the transmitting station side.

An object of the present invention is to provide a transmission device for an STL system that can reduce the wiring cost of a connection cable between a rack room and a penthouse.
Another object of the present invention is to provide a transmission device for an STL system that can reduce the wiring cost of a connection cable between a reception high frequency unit and a reception control unit at a transmission station.

In order to achieve the above object, a transmission apparatus for an STL system according to the present invention has a duplexed main signal circuit system having first and second circuit sections each transmitting and receiving a broadcast IF signal via a main signal line. And an output selection switch that is connected to the output signal line of each of the second circuit units and selectively outputs one of the output signals, and a control unit for controlling the output selection switch, The control unit includes a parent control unit that collects state information of the first circuit unit and a child control unit that collects state information of the second circuit unit, and the parent control unit and the child control unit are a single unit. Connected with the control signal line
The parent control unit periodically selects the main signal circuit system to be output based on the state information of the first circuit unit and the state information on the second circuit unit side received from the child control unit via the control signal line. The system switching control command is output to the control signal line at a predetermined timing, and the child control unit controls the output selection switch according to the switching control command.

  In the STL system on the studio side, the first circuit unit corresponds to a transmission control unit, and the second circuit unit corresponds to a transmission high-frequency unit. In the STL system on the transmitting station side, the first circuit unit serves as a reception high-frequency unit and a second circuit. The unit corresponds to a reception control unit.

  More specifically, the main signal (broadcast IF signal) transmitted and received between the first circuit unit and the second circuit unit is a periodic frame signal having a preamble pattern transmission period at the beginning of the video data transmission period. The parent control unit receives the control pulse PT indicating the preamble period and the reference clock CK from the first circuit unit, and performs the system control at a predetermined timing determined based on the control pulse PT and the reference clock CK. A switching control command is transmitted, and the transmission of the switching control command is stopped at a predetermined timing in accordance with the beginning of the next preamble period.

  The child control unit determines the content of the switching control command received from the control signal line, and switches the output selection switch at a timing in accordance with the stop of transmission of the switching control command when system switching is necessary. In addition, the state information collected from each second circuit unit is transmitted to the control signal line using the remaining period of each cycle except the transmission period of the switching control command. However, the transmission of the status information from the child control unit to the parent control unit does not have to be repeated every frame cycle, and the status information may be transmitted in an N frame cycle (N is an integer of 2 or more).

  According to the present invention, in the duplex transmission apparatus, the system status information and the switching control command are transmitted in a time-division format with a single control signal line, so that the signals are transmitted and received between the units separated from each other. Since the number of signal lines can be reduced, the wiring work time can be shortened and the cable cost can be reduced.

FIG. 1 is a block diagram showing an embodiment of a digital transmission apparatus according to the present invention applied to the studio side of an STL system.
In the digital transmission apparatus of this embodiment, in the conventional studio side apparatus configuration shown in FIG. 5, the switching control unit 3 installed in the rack room 20 is replaced with a parent control unit 30, and a child control unit 31 is provided on the penthouse 21 side. One feature is that it is installed and the parent control unit 30 and the child control unit 31 are connected by a single control signal line 54.

  The child control unit 31 encodes the state information AL2a and AL2b of the transmission high-frequency units 2a and 2b collected through the signal lines 52a and 52b, and transmits the state information ALM on the penthouse side to the control signal line 54 at a predetermined timing. To do. Based on the state information AL1a and AL1b of the transmission control units 1a and 1b collected via the signal lines 51a and 51b and the state information ALM on the penthouse side received from the control signal line 54, the parent control unit 30 A transmission circuit system to be used is determined, and a system switching control command code SC is transmitted to the signal line 54 at a predetermined timing.

  The child control unit 31 generates a switching control signal SEL5 for the output selection switch 5 on the signal line 53 in response to the switching control command code SC. Unless there is a failure in the working system, the switching control command code SC having the same contents is periodically transmitted from the parent control unit 30, and when the control command code SC is switched, the output signal of the output selection switch 5 is changed to the working system. The IF signal is switched to the standby IF signal.

FIG. 2 shows an embodiment of the transmission control unit 1b.
The transmission control unit 1b includes a memory 101 for temporarily storing an input signal (digital video data), a preamble pattern generator 102, a selector 103 connected to the memory 101 and the preamble pattern generator 102, and the above It comprises a modulation circuit 104 that performs single 64QAM modulation on the output signal of the selector 103 and converts it into a 130 MHz IF signal, a controller 105, and a PLL / VCO circuit 106.

The PLL / VCO circuit 106 generates various internal clocks required in the transmission control unit in synchronization with the system clock CK. In FIG. 2, the output clock of the PLL / VCO circuit 106 is represented by the clock CL.
The controller 105 periodically generates a control pulse PT that becomes a high level during the preamble period in synchronization with the internal clock CL, and supplies the control pulse PT to the preamble pattern generator 102 and the selector 103. In addition, the controller 105 outputs the state information AL1b indicating the state of the transmission control unit 1b to the signal line 51b, and the digital video data for one cycle within the period in which the control pulse PT is at the low level (video data transmission period). A control signal CNT for time-compressing and reading is generated, and digital video data is read from the memory 101.

  The selector 103 selects the output of the preamble pattern generator 102 while the control pulse PT is at a high level, and selects the output from the memory 101 while the control pulse PT is at a low level, and supplies the output to the modulation circuit 104. To do. Therefore, a periodic digital signal having a preamble period at the beginning of the video data period is input to the modulation circuit 104.

FIG. 3 shows the output signal of the transmission control unit 1 (1a, 1b) and the transmission timing of the state information ALM and the switching control command code SC that the parent control unit 30 and the child control unit 31 transmit and receive via the signal line 54. Show the relationship.
The two transmission high-frequency units 2a and 2b installed in the penthouse 21 basically have the same circuit configuration. For example, the two transmission high-frequency units 2a and 2b are different in detail characteristics in a microwave band filter. A slight phase delay occurs between the output signals. When the system switching timing is delayed and the preamble period has passed, if switching from the active system to the standby system is performed, the period until the next preamble is received, characteristics such as distortion correction deteriorate, and an error occurs. There are concerns. For this reason, system switching must be performed within the preamble period, preferably at a timing that matches the beginning of the preamble period.

  3A shows the output signal IF-b of the active transmission control unit, for example, the transmission control unit 1b, and FIG. 3B shows the preamble control pulse PT generated by the controller 105. FIG. Since the preamble control pulse PT is at a high level in the leading period T1 of each period T, the output signal IF-b is a periodic signal having the period T1 as a preamble period and the remaining period T2 as a data period.

In this embodiment, in each period (frame period) T of the preamble control pulse PT, the parent control unit 30 and the child control unit 31 use the control signal line 54 in a time division manner. That is, based on the system clock CK and the preamble control pulse PT supplied from the transmission control unit 1b which is the active system, the parent control unit 30 falls the falling t of the preamble control pulse PT as shown in (C). 02, t 12, t 22, timing t04 a predetermined time from ... has elapsed, t14, t24, ... and starts transmission of the switching control command code SC to the signal line 54. The transmission of the switching control command code SC stops when the period ΔT has elapsed. The end timing of the period ΔT is matched with the rising t10, t20, t30 of the preamble control pulse PT.

  The child control unit 31 determines whether or not switching of the system is necessary from the content of the switching control command code SC received from the signal line 54, and when switching to the standby system is instructed, as shown in (F), At the timing when the transmission of the switching control command signal SC is stopped, the switching control signal SEL5 is generated on the signal line 63.

  The child control unit 31 collects the state information AL2a and AL2b from the transmission high-frequency units 2a and 2b using the first half of each cycle T excluding the reception period of the switching control command code SC, and the system state on the penthouse side Is transmitted to the control signal line 54 at a predetermined timing. In the example shown here, as shown in (E), the child control unit 31 starts transmission of the state information ALM at t01, t11, t21,..., And the state information ALM at t03, t13, t23,. Transmission has been stopped.

  As shown in (D), the parent control unit 30 starts the standby operation of the state information ALM from the child control unit 31 at the rising timing of the preamble control pulse PT starting from each cycle, and the state from the child control unit 31 When the information ALM is received, the statuses of the active and standby transmission circuits are determined together with the status signals of the transmission control units 1a and 1b received from the signal lines 51a and 51b, and the timings t04 and t14 described in (C). , T24,..., A switching control command code SC to the control signal line 54 is transmitted.

According to the above configuration, the single control signal line 54 wired between the rack chamber 20 and the penthouse 21 is used for both status information collection and switching control. The number of wirings can be reduced and wiring costs can be greatly reduced. Further, in the time zone allocation of the signal line 54, priority is given to transmission of the system switching control command from the parent control unit in which timing is important as in the embodiment, and the remaining time zone is set to the status information from the child control unit. Therefore, system switching with less signal deterioration in accordance with the preamble period can be performed.
In the above embodiment, the child control unit 31 transmits the state information ALM for each frame period. However, the state information ALM may be transmitted in an N frame period (N is an integer of 2 or more).

FIG. 4 shows a block configuration of an STL system on the transmitting station side to which the feature of FIG. 1 is applied as another embodiment of the present invention.
As described with reference to FIG. 5, in the STL system, the receiving circuit system on the transmitting station side is also duplicated, and when an abnormality is detected in the working receiving circuit, switching to the standby system is performed. The reception high-frequency unit 9 (9a, 9b) is arranged in the vicinity of the reception antenna 7 for the same reason as the transmission high-frequency unit 2 (2a, 2b). A problem similar to that on the studio side occurs with respect to a cable for collecting state information connecting the reception high-frequency unit 9.

  In the present embodiment, the parent control unit 130 is disposed in the vicinity of the reception high-frequency unit 9 (9a, 9b), and the child control unit 131 is disposed in the vicinity of the reception control unit 10 (10a, 10b). The control unit 130 and the child control unit 131 are connected by a control signal line 64 shared by the parent and child. The parent control unit 130 receives the status information of the reception control units 10a and 10b from the child control unit 131 via the control signal line 64, and the status information of the reception high-frequency units 9a and 9b received from the signal lines 61a and 61b. At the same time, the statuses of the working and standby receiving circuits are determined, and the switching control command code SC is transmitted to the control signal line 64 at a predetermined timing. The reception high-frequency unit 9 (9a, 9b) includes a synchronization circuit for detecting a preamble in the reception signal and establishing internal synchronization, and therefore a preamble control pulse necessary for determining the transmission period of the switching control command code SC. PT can be obtained from the synchronization circuit.

  When a clock asynchronous with the transmission control unit 1 (or reception high frequency unit 9) is applied as the reference clock of the parent control unit 30 (or 130), the phase of the rising / falling edge of the preamble control pulse Pt and the reference clock is Since they do not necessarily match, a deviation occurs between the transmission end timing of the switching control command code SC and the period of the main signals IF-a and IF-b, and when the system is switched by the output selection switch 5 (or 11). There is a risk that a part of the preamble is lost.

  However, in the above-described embodiment of the present invention, the parent control unit 30 (or 130) uses the system clock CK of the transmission control unit 1 (or reception high-frequency unit 9) and this and the transmission control unit 1 (or reception high-frequency unit). Since the transmission period of the switching control command code SC is determined based on the preamble control pulse PT generated in the section 9), the above-mentioned problem due to clock asynchronousness does not occur. In order to determine the transmission period, a reference clock synchronized with the clock used by the transmission control unit 1 (or the reception high-frequency unit 9) may be applied. For example, instead of the system clock CK, for example, the transmission control unit 1 The internal clock CL generated by the PLL / VCO circuit 106 may be used.

The figure which shows one Example of the digital transmission apparatus by this invention applied to an STL apparatus. The block diagram which shows one Example of the transmission control part 1b in FIG. 2 is a timing chart showing an operation of the digital transmission apparatus shown in FIG. The figure which shows the other Example of the digital transmission apparatus by this invention applied to an STL apparatus. The figure which shows an example of the conventional digital transmission apparatus applied to an STL apparatus.

Explanation of symbols

1: transmission control unit, 2: transmission high-frequency unit, 3: switching controller, 5: output selection switch,
6: Transmitting antenna, 7: Receiving antenna, 8: Distributor, 9: Reception high-frequency unit,
10: Reception control unit, 11: Output selection switch, 30, 130: Parent control device,
31, 131: Child control devices.

Claims (2)

A duplexed main signal circuit system having first and second circuit portions, each connected via a main signal line, and one of the outputs connected to the output signal line of each second circuit portion. A transmission device for an STL system comprising an output selection switch for selectively outputting a signal and a control unit for controlling the output selection switch,
Each of the first circuit units transmits a periodic broadcast IF signal having a preamble pattern transmission period at the beginning of the video data transmission period to the second circuit unit connected by the main signal line,
The control unit includes a parent control unit that collects state information of the first circuit unit and a child control unit that collects state information of the second circuit unit.
The parent control unit and the child control unit are connected by a single control signal line,
The main signal circuit system to which the parent control unit should select the output based on the state information of the first circuit unit and the state information on the second circuit unit side received from the child control unit via the control signal line Periodically, and at a predetermined timing within the video data transmission period, a system switching control command code is output to the control signal line,
The child control unit transmits the state information on the second circuit unit side to the control signal line within the first half period of each cycle excluding the reception period of the switching control command code, and according to the switching control command code The transmission apparatus controls the output selection switch at a timing in accordance with the beginning of the preamble pattern transmission period. The transmission apparatus according to claim 1, wherein
The parent control unit receives a reference clock and a control pulse indicating a transmission period of the preamble pattern from the first circuit unit, and outputs the switching control command code based on the reference clock and the control pulse. A transmission apparatus characterized by determining

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