JPH10290217A - Synchronizing signal switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the synchronizing signal switching device by which an internal synchronizing signal is secured so long as all frame synchronizing signals are not lost. SOLUTION: For example, higher priority is placed in the order of a reference synchronizing signal (d), an extracted synchronizing signal (b), an extracted synchronizing signal (g) and a priority setting signal (k). Supposing that the reference synchronizing signal (d) is lost, a changeover control circuit 5 has selected so far the reference synchronizing signal (d) as an internal synchronizing signal (e). The moment when the reference synchronizing signal (d) is lost, a signal detector 4-3 detects loss of the synchronizing signal, a signal detector 4-1 confirms the presence of the extracted synchronizing signal (b) according to the priority setting signal (k) to control a synchronizing signal changeover device 2 and selects the extracted synchronizing signal (b) as the internal synchronizing signal (e).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous signal switching device, and more particularly to a synchronous switching device for digital audio signals in a broadcasting station.

[0002]

2. Description of the Related Art In recent radio and television broadcasting stations, an original analog audio signal is sampled at, for example, 48 kHz, quantized to 16 bits or 24 bits, and serialized after a 48 kHz frame synchronization signal, for example. For example, L from the MSB (most significant bit)
The transmission up to the SB (least significant bit) as a serial digital audio signal has been performed.

Therefore, the phase of the frame synchronization signal needs to match within the broadcasting station (if the phase of the frame synchronization signal does not match, unnatural noise may occur at the time of signal switching, or signal mixing may occur. Or fade-in / out cannot be performed).

Normally, a broadcasting station has a reference (frame) synchronization signal of, for example, 48 kHz (in the case of a television broadcasting station, the phase is often locked to a synchronization signal of a video signal). In many cases, the (frame) synchronization signal of the audio signal is matched with the reference (frame) synchronization signal. However, if an abnormality occurs in the reference (frame) synchronization signal, some measure is required.

FIG. 2 shows a configuration of a conventional audio digital (frame) synchronization signal switching device. In FIG. 2, an audio digital signal (NET reception signal) from another broadcasting station
The extracted synchronizing signal b is separated from the a by the synchronizing signal extractor 1. The synchronization signal switching unit 2 selects an internal synchronization signal e (usually a reference synchronization signal d) from the reference (frame) synchronization signal d or the extracted synchronization signal b, and becomes a frame synchronization signal for all audio equipment of the broadcasting station. ). For example, when the reference synchronization signal d is selected as the internal synchronization signal e, the audio digital signal a and the internal synchronization signal e are generally completely independent of each other and are not phase-synchronized.

The phase synchronizer 3 is an audio signal frame synchronizer for matching the frame phases of the audio digital signal a and the internal synchronization signal e. For example, the phase synchronizer 3 converts a serial audio digital signal a into a 16 or 24 bit parallel signal. , And store it in a memory having a storage capacity of, for example, two frames in a form that is sequentially updated. When the stored parallel audio signal is read by the internal (frame) synchronization signal e, the read parallel audio signal becomes
The phase is synchronized with the internal synchronization signal e. A (frame) synchronization signal is added to the parallel audio signal to obtain a serial audio digital signal c.

[0007]

In the case of the conventional synchronizing signal switching apparatus shown in FIG. 2, an internal synchronizing signal serving as a reference for all audio equipment is an extracted synchronizing signal separated from an input audio digital signal or a reference (frame). Since any one of the synchronization signals is fixedly selected, when an abnormality (for example, disconnection) occurs in the selected (frame) synchronization signal, a problem such as a disconnection of the internal synchronization signal occurs.

It is an object of the present invention to provide a synchronous signal switching device which can secure an internal synchronous signal unless all frame synchronous signals are lost.

[0009]

A synchronization signal switching device according to the present invention comprises: frame synchronization signal extraction means for extracting an extraction frame synchronization signal from an input audio digital signal;
An internal synchronization signal selecting unit that selects one of the extracted frame synchronization signal and the reference frame synchronization signal and sets the selected internal synchronization signal as an internal synchronization signal. A synchronizing signal detecting means for detecting the presence of each of the signals, and the internal synchronizing signal is selected based on a predetermined priority setting signal from among the frame synchronizing signals confirmed to be present by the synchronizing signal detecting means. Switching control means for controlling the internal synchronization signal selection means.

Further, the priority setting signal sets the reference frame synchronization signal as the highest priority.

[0011] Further, it is characterized in that it comprises a phase synchronizing means for synchronizing the frame phase of the audio digital signal with the internal synchronizing signal.

The operation of the present invention is as follows. Extracting an extracted (frame) synchronization signal from each audio digital signal, and detecting the presence of the frame synchronization signal together with a reference (frame) synchronization signal, according to a predetermined priority, and according to a predetermined priority. Select a signal.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a synchronization signal switching device according to the present invention, and the same parts as those in FIG. 2 are denoted by the same reference numerals.

The synchronous signal switching apparatus according to the present invention shown in FIG. 1 comprises synchronous signal extractors 1-1 to 1-n for extracting extracted synchronous signals b and g from audio digital signals a and f, and an extracted synchronous signal b. , G, etc., the signal detectors 4-1 to 4-n for detecting the presence of the reference synchronization signal d, the synchronization signal switch 2, for selecting the internal synchronization signal e from the reference synchronization signal d, such as the extracted synchronization signals b, g, On the basis of the priority set by the priority setting signal k, the signal detectors 4-1 to 4-n select the internal synchronization signal e from the (frame) synchronization signals for which the existence of the (frame) synchronization signal has been confirmed. A switching controller 5 for controlling the synchronization signal switching unit 2 so that the audio digital signals a, f, etc. are phase-synchronized with the internal synchronization signal e to generate audio digital signals c, h, etc., which are phase-synchronized with the internal synchronization signal e. Phase synchronization Consisting of 3-1~3-n.

In the operation of the embodiment of the present invention, it is assumed that, for example, a reference synchronization signal d, an extraction synchronization signal b, and an extraction synchronization signal g are set k in descending order of priority. Now, assuming that the reference synchronization signal d has disappeared, the switching controller 5 has selected the reference synchronization signal d as the internal synchronization signal e so far. 3 detects that the synchronizing signal has disappeared, the signal detector 4-1 confirms the presence of the extracted synchronizing signal b according to the priority order setting k, and the switching controller 5 controls the synchronizing signal switcher 2, The extracted synchronization signal b is selected as the internal synchronization signal e.

The phase synchronizers 3-1 to 3-n determine the frame phases of the audio digital signals a and f and the internal synchronization signal e,
A very small audio signal frame synchronizer, such as a serial audio digital signal a
Is converted into a parallel signal of, for example, 16 or 24 bits, and is stored in a memory having a storage capacity of, for example, two frames in a form of being sequentially updated. When the stored parallel audio signal is read by the internal (frame) synchronization signal e, the read parallel audio signal is phase-synchronized with the internal synchronization signal e. A (frame) synchronization signal is added to the parallel audio signal to obtain a serial audio digital signal c.

[0018]

As described above, according to the present invention, by setting priorities in advance, there is an effect that an internal synchronization signal can be always secured as long as all frame synchronization signals are not lost.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional synchronization signal switching device.

[Explanation of symbols]

 1-1 to 1-n Synchronous signal extractor 2 Synchronous signal switch 3-1 to 3-n Phase synchronizer 4-1 to 4-n Signal detector 5 Switching controller

Claims (3)

[Claims] 1. A frame synchronization signal extracting means for extracting an extracted frame synchronization signal from an input audio digital signal;
An internal synchronization signal selecting means for selecting one of the extracted frame synchronization signal and the reference frame synchronization signal to be an internal synchronization signal, wherein the extracted frame synchronization signal and the reference A synchronizing signal detecting means for detecting the presence of each of the frame synchronizing signals, and selecting the internal synchronizing signal based on a predetermined priority setting signal from the frame synchronizing signals confirmed to be present by the synchronizing signal detecting means Switching control means for controlling the internal synchronizing signal selecting means so as to perform the synchronization signal switching. 2. The synchronization signal switching device according to claim 1, wherein the priority setting signal sets the reference frame synchronization signal to the highest priority. 3. The synchronization signal switching device according to claim 1, further comprising phase synchronization means for synchronizing a frame phase of said audio digital signal with said internal synchronization signal.