JP2003032320A - Digital wireless communication device provided with hitless switching circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hitless switching circuit that can replace an active transmitter with a standby transmitter without freezing a video signal. SOLUTION: This invention provides a method for employing the hitless switching circuit that takes clock, local, frame synchronization between the active system and the standby system and enabling a switching control panel to deviate a switching timing outputted between the active system and the standby system, thereby switching the active transmitter into the standby transmitter, without having to freeze video signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for switching transmitters when a failure occurs in a digital wireless communication device.

[0002]

2. Description of the Related Art In a single switching switch, when the transmitter output is switched, the transmission output is cut off, so that there is a problem that a received image is frozen.

In Japanese Patent Laid-Open No. 2000-324072,
This paper describes a method for realizing non-instantaneous switching by synchronizing the pointer processes of both systems when switching devices due to a failure in the SDH transmission system.

In Japanese Laid-Open Patent Publication No. 11-298452, at the time of switching between an active system and a standby system in which the phase of the frame pulse does not match, a delay circuit until the next frame pulse is received causes the same frame Describes a non-instantaneous interruption switching device that can switch between each other.

In Japanese Patent No. 2806913, when the active system is switched to the standby system device, the active switching signal changes, and after the active system clock is stopped, the standby system clock output is started. However, the standby system clock output is started. It describes an output signal switching circuit that solves the occurrence of instantaneous interruption and pulse noise that occur because it takes a certain amount of time.

[0006]

In these prior arts, Japanese Patent Laid-Open No. 11-298452 discloses a method in which the phase synchronization of the frame synchronization signal is limited, and Japanese Patent No. 280
Japanese Patent No. 6913 is a method limited to the synchronous synchronization of the output clocks for switching the output signals, and there is a problem that the continuity of the output RF signals does not guarantee the prevention of the freeze of the video signals. It was

The present invention has been made in view of these problems, and an object of the present invention is to provide a method and an apparatus for switching a transmission apparatus without an interruption without fail to prevent a freeze of a video signal.

[0008]

According to a first aspect of the present invention, in a digital radio communication apparatus having a working standby system configuration, a working means for transmitting an RF signal to the apparatus, and the means. Switching switch means of the active system corresponding to, the transmission means of the standby system for transmitting an RF signal to the device, the switching SW means of the standby system corresponding to the means, the transmission timing of the RF signal to the switching SW means group Switching control means for shifting and controlling the switching, and switching by the control means
A synthesizing means for synthesizing RF signals into a continuous RF signal,
There is provided a digital wireless communication device having a hitless switching circuit, which is characterized by including the following.

According to a second aspect of the present invention, in a digital wireless communication method having a configuration of a working protection system, a working system transmitting step for transmitting an RF signal to the device, and a working system corresponding to the step. Switching SW step, standby system transmission step for transmitting an RF signal to the device, standby system switching SW step corresponding to the step, and the switching
A switch control step of controlling the switching by shifting the transmission timing of the RF signal to the SW step group, and a synthesizing step of synthesizing the RF signals switched by the control step into a continuous RF signal, A digital wireless communication method including a hitless switching circuit is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the functional block diagram of FIG. 1 showing the functional configuration of the present invention.

The active transmitter 1 and the standby transmitter 2 digitally modulate the input data and convert it into an RF signal.

Further, the local signals of the active transmitter 1 and the standby transmitter 2 are synchronized with each other by the frame synchronization signal and the clock signal.

The switch SW3 and the switch SW4 switch the output signal to the synthesizer 5 according to the switch control signal of the switch control board 6.

The synthesizer 5 synthesizes and outputs the output signals of the switching SW 3 and the switching SW 4.

The switch control board 6 outputs a switch control signal independently to the switch SW3 and the switch SW4.

Next, FIG. 2 shows the configuration of the clock and local synchronizing circuit in the active transmitter 1.

The clock and local synchronizing circuit in the active transmitter 1 divides the input signal by frequency dividers 201, 202,
A phase comparator 203 for comparing the clock or local phase of the active system and the standby system, a loop filter 204 for attenuating harmonics and noise components included in the output of the phase comparator,
VCO2 whose output frequency can be changed according to the input voltage
It consists of 05.

Next, FIG. 3 shows the configuration of the frame synchronization circuit in the transmitter of the active system.

The frame synchronizing circuit in the working transmitter is composed of an OR circuit 301 for synchronizing the frames in the working system and the standby system, and a frame counter 3 for generating a frame synchronizing signal.
It consists of 02.

Next, an example of a detailed embodiment of the switching control board 6 is shown in FIG.

The switching control board 6 includes a switching SW 401 for switching between the active system and the standby system, a delay line 402 and a delay line 403 for adjusting control timing, a selector 404 and a selector 40 for selecting switching control timing.
5. Inverter 406 that inverts the control of the working system and the standby system
And an inverter 407.

Next, the circuit operation in the example of the embodiment will be described with reference to FIG.

In the circuit operation shown in FIG. 1, the transmission data is distributed and input to the active transmitter 1 and the standby transmitter 2.

Each of the transmitters obtains a modulated signal by a predetermined coding and modulation method,
It is converted to RF frequency by the frequency converter and output.

Further, the respective transmitters are frequency and phase synchronized with each other by the circuit shown in FIG.

The circuit of FIG. 2 is a PLL (Phase Lock Loop) conventionally used for frequency and phase synchronization.

In FIG. 2, frequency dividers 201 and 202 divide the frequency to the frequency at which the phase comparator operates, and phase comparator 203 compares the phases of the signals of the standby system and the working system and loops the output. The filter 204 cuts harmonic components and controls the VCO 205 to establish frequency and phase synchronization.

Further, in the circuit of FIG. 3, the OR circuit 301 determines the initial phase of the frame counter of the active system, so that the frame synchronization of the active system and the standby system is established.

The data input at a certain time by the circuits of FIGS. 2 and 3 are transferred from the working transmitter 1 and the spare transmitter 2 to
It is output as an RF signal at the same time.

Next, the operation of the changeover switch 3, the changeover switch 4, the changeover control panel and the combiner will be described with reference to FIGS. 1 and 4 and FIG. 5 which shows a timing chart during the changeover operation.

1 and 5, when the active transmitter 1 is selected by the switch control panel 6, the output of the active switch is selected as the output of the switch SW3 and no signal is output as the output of the switch SW4. It As a result, as the output of the synthesizer 5, only the output signal of the transmitter of the active system is output.

In FIG. 4, the switch SW 401 switches the active standby system, and the signal output from the switch SW 401 passes through the inverter 406 and the selector 405,
Immediately after being output as a standby system switching control signal, the delay line 402 delays the switching time of the switching SW3 of FIG. 1 and then passes through the selector 404 and is output as an active system switching signal.

After the switching is completed, the signal which has passed through the delay line 403 is prepared for the next switching operation, so that the selectors 404 and 405 are switched to the opposite side to turn the SW in order to reverse the control delay. It is possible to switch without interruption when the transmission signal is switched.

[0034]

The first effect of the present invention is that the image does not freeze when the transmitter is switched from the active system to the standby system.

The second effect of the present invention is that continuous data transmission can be guaranteed without interruption.

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of an example in an embodiment of the present invention.

FIG. 2 is a clock of an example in the embodiment of the present invention.
/ It is the block diagram which showed the example in a local synchronous circuit.

FIG. 3 is a block diagram showing a configuration of a frame synchronization circuit of an example in the exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a detailed configuration of a switching control board according to an example of the embodiment of the present invention.

FIG. 5 is an operation timing chart of the switching control board according to the example of the embodiment of the present invention.

[Explanation of symbols]

1 Working transmitter 2 Spare transmitter 3 switching switch 4 switching switch 5 synthesizer 6 switching control panel 201 divider 202 divider 203 Phase comparator 204 loop filter 205 VCO (voltage controlled oscillator) 301 OR circuit 302 frame counter 401 switching switch 402 delay line 403 delay line 404 selector 405 selector 406 inverter 407 inverter

Claims (2)

[Claims] 1. A digital wireless communication apparatus having a configuration of a working standby system, wherein a working means for transmitting an RF signal to the apparatus, a working SW switching means corresponding to the means, and an RF for the apparatus. Standby system transmitting means for transmitting a signal, standby system switching SW means corresponding to the means, switching control means for shifting the RF signal transmission timing to the switching SW means group to control switching, and the control means A digital wireless communication device having a hitless switching circuit, comprising: a synthesizing unit for synthesizing an RF signal switched by the above to obtain a continuous RF signal. 2. A digital wireless communication method having a configuration of a working standby system, wherein a working system transmitting step for transmitting an RF signal to the device, a working system switching SW step corresponding to the step, and an RF system for the device. A standby system transmission step for transmitting a signal, a standby system switching SW step corresponding to the step, a switching control step for shifting the RF signal transmission timing to the switching SW step group to control switching, and the control step A digital wireless communication method comprising a hitless switching circuit, comprising: a synthesizing step of synthesizing RF signals switched by the method to obtain a continuous RF signal.