JPH0683199B2 - Burst signal transmission system - Google Patents

Description

The present invention relates to a burst signal transmission system, and more particularly to a burst signal transmission system in a digital communication system.

[Conventional technology]

While audio signals are continuously input, they are digitized and sent in bursts. Alternatively, when a series of data information to be transmitted is sent in bursts, the data signal to be sent is framed and the framing bit (fr
Place a specific pattern for frame synchronization called aming bit).

The demodulator of the receiving station locks synchronization to one burst while receiving one burst sent from a certain transmitting station,
When the reception is completed, the fixed synchronization is released, and the system shifts to the initial mode of waiting for the next burst from this transmitting station or another transmitting station. In order to perform this operation mode transition quickly and reliably, a pattern called an end of burst (EOB) is placed at the end of the burst so that the reception side can detect the completion of reception of the burst.

The conventional burst signal transmission method uses a pattern in which framing bits are repeated as one EOB over a length of one or two frames. When this number of repetitions is M times, the reception side determines that the reception of the burst is completed when the framing bit is detected N times (N ≦ M) of M times in succession in consideration of a transmission error.

[Problems to be Solved by the Invention]

The above-mentioned conventional burst signal transmission method uses the EOB on the receiving side.
Is detected by the majority decision, the new signal to be transmitted while the transmitting station is sending EOB enters this transmitting station and starts sending the next burst from the next frame after the completion of sending EOB. In some cases, the framing bit and the framing bit at the beginning of the next burst may be indistinguishable. In this case, the demodulator of the receiving station is in the initial mode at the beginning frame of the next burst and it takes a certain amount of time for synchronization. It costs. Therefore, reception cannot be performed until the demodulator is synchronized, and for example, if the signal to be transmitted is a voice signal, there is a drawback that the topic is cut off.

An object of the present invention is to provide a burst signal transmission method in which the receiving side can reliably receive the next burst from the beginning even if the transmitting station starts to send the next burst from the next frame after the completion of the EOB transmission. is there.

[Means for Solving the Problems]

According to the burst signal transmission method of the present invention, a finite length digital signal to be transmitted is framed on the transmission side, a predetermined first pattern is arranged at the head of each frame, and the first bit is arranged after the last bit of the digital signal. In a burst signal transmission system in which a second pattern, which is a predetermined plurality of repetitions of the above pattern, is arranged and transmitted in a burst form, a new signal to be transmitted during the transmission of the second pattern is transmitted to the transmission side. When input, the first pattern in the first frame corresponding to the new signal is set to a predetermined third pattern different from the first pattern.
When the burst is exchanged with the pattern No. 3 and the third side is detected at the beginning of the first frame after the second pattern is detected, the receiving side continuously demodulates the third pattern When no pattern is detected, the demodulation initial mode is entered.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a time chart showing a burst frame structure in an embodiment of the present invention.

The following description will be given assuming that the signal to be transmitted is a voice signal.

When a voice signal is input to a certain transmitting station, a voice detector detects the voice signal and outputs a detection signal. While this detection signal continues, the audio signal is digitized by the encoder and framed. At the beginning of each frame, a framing bit F is arranged as shown by F in FIG. Framing Bit F
Is a specific pattern consisting of 16 bits, for example.
Information bits of a digitized audio signal are arranged in a period excluding the framing bit F of each frame.
When the input of the voice signal ends and the detection signal of the voice detector disappears, EOB which is M times of the framing bit F is arranged after the last information bit, and the bit string thus created is the first. It is sent as a burst as shown in the figure. The number of repetitions M is set so that the length of the EOB becomes, for example, one frame length.

The receiving station which receives this burst synchronizes the frame with the burst to be received by detecting the framing bit F in the received signal, and thereafter fixes the synchronization of the demodulator to this burst and receives until the EOB is detected. continue. As described above, the EOB is detected by the majority decision to detect the framing bit F N times out of M times in succession. Even if the EOB is detected, the synchronization of the demodulator is kept fixed at least until the timing when the framing bit of the next frame is located, as described later.

Now, when a new voice signal is input to this transmitting station while the transmitting station is transmitting EOB and the voice detector outputs the detection signal again, the transmitting station outputs the next burst corresponding to this new voice signal to the EOB of the previous burst. Starts to be sent from the frame next to the frame that has finished sending. However, in this case, the framing bits of the first frame of the next burst are
The framing bit F, which is an inverted pattern of each bit of the framing bit F, is replaced. FIG. 1 illustrates this case.

On the other hand, the receiving station continues to fix the synchronization of the demodulator even after detecting EOB, and waits for the framing bit at the timing of the beginning of the first frame after detecting EOB. When the framing bit is detected, it is determined that the next burst is transmitted from the same transmitting station following the previous burst, the synchronization of the demodulator is further fixed, and the next burst is received. If no framing bit is detected, the demodulator synchronization is released, and the system shifts to the initial mode of waiting for the next burst from the same transmitting station or another transmitting station.

When transmitting the next burst following the previous burst strike from the same transmitting station, the framing bit pattern placed at the beginning of the next burst can be easily converted into the framing bit F by inverting the pattern of the normal framing bit F. Of the previous burst
Even if the framing bit F in the EOB and the framing bit at the beginning of the next burst come close to each other, the beginning of the next burst can be reliably detected. The framing bit pattern placed at the beginning of the next burst is the EO of the previous burst.
A pattern that is easy to discriminate from the framing bit F in B and is suitable for frame synchronization may be used, and it is not always necessary that the pattern is an inversion pattern of the framing bit F.

〔The invention's effect〕

As described above, according to the present invention, the EOB is the repetition of the first pattern in which the transmitting side is the framing bit a plurality of times.
When the next burst is started to be transmitted from the next frame after the completion of transmission, the framing bit pattern placed at the beginning of the next burst is set to a third pattern different from the first pattern, and the receiving side detects EOB. By confirming that the third pattern is not detected at the beginning of the first frame after that, the system shifts to the initial mode, so that even if the transmitting station transmits the next burst following the previous burst, This has an effect that the beginning of the next burst can be detected with certainty and the beginning frame of the next burst can be prevented from being unreceivable.

[Brief description of drawings]

FIG. 1 is a time chart showing a burst frame structure in an embodiment of the present invention. F, …… Framing bit.

Claims (1)

[Claims] 1. A finite length digital signal to be transmitted at a transmitting side is framed, a predetermined first pattern is arranged at the beginning of each frame, and the first pattern is preliminarily arranged after the last bit of the digital signal. In a burst signal transmission method in which a second pattern, which is a plurality of predetermined repetitions, is arranged and transmitted in a burst form, when a new signal to be transmitted is input to the transmission side during transmission of the second pattern, this new signal is transmitted. In response to the signal, a burst in which the first pattern in the first frame is replaced with a predetermined third pattern different from the first pattern is transmitted, and after the second pattern is detected on the receiving side. If the third pattern is detected at the beginning of the first frame of, the demodulation is continued and the third pattern is not detected. Burst signal transmission method characterized by moving the initial mode of the demodulation case.