JPS63200664A - Signaling transmission system - Google Patents

Abstract

PURPOSE:To attain the transmission of high speed data by stopping. multiplication by a bit steal of a singling signal at the transmission of a MO DEM signal or prolonging its period so as to improve the transmission quality of the MODEM data. CONSTITUTION:The signaling signal is used to transfer dial and hook information, and the hook information has only to be discriminated by the receiver side as to whether it is in the hook off or on state and it is not required to send in the same frequency as the dial information during the transmission. Then at the transmission of the MODEM signal, the bit steal period of the signaling signal (hook information) is prolonged longer than that at the transmission of the voice signal. Or the signaling signal is sent in a multi-frequency tone, the transmission of the signal is stopped at the transmission of the voice or MODEM signal and instead of it, the receiver side generates the signaling signal in a pseudo way. Or the signaling signal is sent in bit steal and the bit steal is stopped at the transmission of the MODEM signal and the receiver side generates the signaling signal in the pseudo way. Thus, high quality MO DEM data transmission is attained.

Description

[Detailed Description of the Invention] [Summary] When transmitting a modem data signal using an ADPCM voice encoding device, bit stealing of the signaling signal sent in the in-slot method is stopped or the The period is lengthened, thereby improving the transmission quality of the data signal.

[Industrial application field]

The present invention relates to a signaling transmission method in an ADPCM voice encoding device capable of transmitting not only voice signals but also modem data signals.

[Conventional technology]

The ADPCM audio encoding device not only encodes audio signals but also encodes FA
It can also be used to transmit modem data such as X.

Figure 9 is a configuration diagram of a system using 32 Kb/s ADPCM, where 1 is an A/D converter, 2 is an ADPCM encoder,
3 is a transmission path, 4 is an A'DPCM decoder, 5 is a D/A converter, 6 is an AC PA device, and 7 is a telephone device.

The voice signal from telephone 7 is digitized through exchange 6 and A/D converter 1, further encoded by encoder 2, and sent to transmission line 3. 8 for 32Kb/S ADPCM
Each sample is sampled at 8 bits and compressed to 4 bits. D3 to Do in FIG. 10 indicate the 4 bits. The exchange 6 needs to send the hook-on/off information and dialing signal of the telephone 7 to the other side's exchange, and this is done by setting the off signal to the "1" level and superimposing dial pulses of "1" and 0 on it. , on-hook is performed at 0” level. Such a signal is called a signaling signal, and is sent directly from the exchange 6 to the ADPCM encoder 2.

There are two methods for transmitting signaling signals. One is an out-slot method that uses a slot separate from that for the audio signal. This method has the disadvantage of narrowing the band that can be used for audio signals. The other method is an in-slot method in which a signaling signal is inserted into the audio signal by bit stealing. For example, the lowest data bit DO in FIG.
It is regularly replaced with a signaling signal (indicated by diagonal lines) with a period of ms (IKH2), and the receiver separates and extracts this signal in terms of timing.

[Problem that the invention seeks to solve]

By the way, when a signaling signal is inserted using the in-slot method, a certain bit of the data is removed (bit stealing) and a signaling signal is used instead, which inevitably lowers the quality of the transmitted data. Of course, as shown in FIG. 10, the LSB, which has little influence, is targeted for bit stealing, and bit stealing is limited to once every l m s to ensure transmission quality. However, in the case of voice signals, there is a strong correlation between the front and rear voice codes, so there is little deterioration in voice quality, but in modem data, this bit stealing causes phase distortion, causing modem data errors. In particular, when there is a demand for multi-link connections, it becomes necessary to improve transmission quality using the in-slot method.

With ADPCM of 32 Kb/s, the upper limit of the data rate that can be transmitted is limited, and although data such as 4800 b/s can be transmitted, higher speed data such as V29CI FAX cannot be transmitted. Traditional 32Kb
/s ADPCM automatically switches between voice mode and modem mode to pass 9600 b/s modem data, and when modem data is input, an ADPCM code with quantization characteristics most suitable for the characteristics of the modem data is used. Make sure to do this. However, when bit stealing is performed, the lowest focus of the ADPCM code changes to signaling at a certain period, which causes an error.
One link is the limit for b/s modem data.

The present invention improves the transmission quality of modem data by devising a signaling signal transmission method, thereby enabling high-speed data transmission.

[Means for solving problems]

The present invention relates to a signaling transmission method in which a voice signal or a modem signal is encoded, and a signaling signal having dial information for line selection and hook information for line maintenance is multiplexed and transmitted using an in-slot method. This is characterized by stopping the multiplexing of the signaling signal by bit stealing or lengthening its cycle.

[Effect]

As mentioned above, signaling signals are used to transmit dial information and hook information, but for hook information, it is only necessary for the receiver to be able to determine whether it is off-hook or on-hook. Therefore, (1) the bit steal period of the signaling signal (hook information) is longer when transmitting the modem signal than when transmitting the voice signal, (2) the signaling signal is
(Multi-frequency) tone transmission method, and when transmitting voice or modem signals, the transmission of signaling signals is stopped, and instead a pseudo signaling signal is generated on the receiver side. (3) The signaling signal is a bit-based signal. I will send it in steel, but
High-quality modem data transmission is possible by stopping bit stealing when transmitting modem signals and instead generating a pseudo signaling signal on the receiver side (bit stealing is performed when transmitting voice signals). Become.

〔Example〕 FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the figure, ■ is an A/D converter that converts an analog audio signal or modem signal into a digital signal, and 11 is an A/D converter that determines whether it is an audio signal or a modem signal based on the difference in signal format (1 & 2 have training patterns). Detection circuit, 12 is audio/
A circuit multiplexes modem signals and signaling signals in an in-slot manner, and 13 is a circuit that generates a clock for bit stealing. These circuits 11 to 13 are ADPC
Included in M encoder 2. Of these, the detection circuit 11 outputs a switching signal that lowers the frequency of the bit stealing clock during modem signal transmission.

FIG. 2 shows a specific example, in which the detection circuit 11 includes a digital processor DSP and a parallel/serial converter P/S, and performs not only the above-mentioned signal discrimination but also ADPCM encoding processing. The clock generator 13 prepares two types of clocks for bit stealing, and selects IKHz when transmitting an audio signal, and selects 0.5 KHz when transmitting a modem signal. SEL' is a selector for this purpose. Multiplexer 12
The selector SEL multiplexes the coded voice/modem signal and the signaling signal (which is originally a pulse). FF is a flip-flop that launches its output, and 8KH2 is used as its operating clock.

Figure 3 is a time chart showing the operation of Figure 2. During audio data transmission, a signaling signal (
The shaded area (more specifically, this part consists of 4 bits, but only the LSB is omitted) is inserted, whereas during modem data transmission, it is inserted once every 16 samples by a 0.5 KHz focus steal clock. The proportion is decreasing rapidly. Note that this is about the hook-off information after the line is connected, and the dial information before the line is connected is bit-stealed at the same cycle in either case. In the example shown in FIG. 3, this period is 1 ms, which is a value that takes into account distortion of dialed numbers. Via during communication) Steal period 1
/ 0.5 seconds is not limited to this, and may be longer. However, at the other party's exchange, for example, 32 m5
Since the line is disconnected when hook-on information is detected three times in a row by sampling at the ec period, the maximum value of the bit steal period for modem data is limited from this value.

FIG. 4 is a block diagram of a second embodiment of the present invention.

In this example, a transmission signaling signal (pulse) inputted from the exchange is converted into an MF signal, and then encoded and transmitted in the same way as a voice/modem signal. Bit stealing is not used to transmit signaling signals; the transmission of signaling signals is stopped during the transmission of voice/modem signals, and instead the receiver determines the hook-on/off status from the noise level of the line and the transmission procedure.

FIG. 4(a) is a block diagram of the ADPCFI encoder 2.
MF input transmission signaling signal (pulse) 33
The circuit for converting to tone, 22 is a selector for selecting either MFI-tone or voice/modem data after A/D conversion.Normally, converter 21 is selected, and when the line is connected, voice/modem data is selected. Choose a side.

23 is a comparator that compares the noise level of voice/modem data with a reference value; 24 is a circuit that delays its output for a certain period of time; and 25 is a ΔKo CM encoder that encodes the output of the selector 22. On the other hand, in the same figure (bl is a configuration diagram of the ADPCM decoder 4, 26 is an ADPCM decoder that decodes the encoded signal received from the transmission path 3, and 27 is a comparison of the noise level of its output with a reference value. AND is an AND gate that takes the logical product of the output of the comparator 27 and the signaling signal (pulse) SS', 28
is the output of the AND gate AND, and 1 is the selector that sends the output of the converter 26 to the converter 29 or to the audio/modem, 29 is the converter that converts the FM)-tone into a signaling signal (pulse), and OR is the converter. This is an OR gate that takes the logical sum of the output of 29 and the output of the AND gate AND and outputs the received signaling signal SR'.

When the input line of the exchange is connected, only signaling signals are transmitted in MF tones. At this time, no audio signal is input. When the dial pulse is transmitted by the MF)-- and the line connection is completed, the comparator 27 generates an output due to the noise level on the line and opens the gate MF-AND.

On the receiving side, when the MF)-on (dialing) is completed, a signaling signal SS' is generated, which passes through the gate AND and is input to the selector 28 and the OR gate OR.

Therefore, as shown in the figure, the output SR' of the OR game FOR is first the output of the converter 29 for the SS sent, and then becomes the SS'. The selector 28 also switches to transmit the output of the decoder 26 to the voice/modem system. Also on the transmitting side, comparator 23 produces an output which, after a delay by circuit 24, switches selector 22 to the voice/modem side, thereby transmitting voice/modem data.

When the data transmission is finished, the input line is disconnected and the output line to the exchange is disconnected. When on-hook, the transmitting comparator 23 returns the selector 22 to the converter 21, and then the receiving comparator 23 also returns the selector 28 to the converter 29.
Move it back to the side, thus returning to the initial state.

FIG. 6 is a block diagram of a third embodiment of the present invention.

This example is based on a method of transmitting a signaling signal by bit stealing as in the embodiment shown in FIG. 1, but during transmission of modem data, bit stealing is completely stopped and no signaling signal (hook-off information) is sent.

Instead, a pseudo signaling signal is generated on the receiving side.

The ADPCM encoder 2 includes an ADPCM encoder 31 that encodes an A/D-converted voice/modem signal, a circuit 32 that multiplexes its output and a signaling signal (pulse) using bit stealing, and the encoder 31. and a circuit 33 for detecting a modem signal from the output.

This detection unit 33 identifies modem signals based on signal form characteristics such as training patterns. If a modem signal is detected and line l is connected, a signal 34 is sent through this line to stop bit stealing in the multiplexer 32. This signal 34 is the audio/video output from the encoder 31.
Also used for modem mode switching.

〇The PCM decoder 4 includes an ADPCM decoder 35 that decodes the encoded signal from the transmission path 3, a modem signal detection section 36 that detects a modem signal from the output thereof, and a decoder 35.
a separation/multiplexing section 37 that separates the voice/modem signal from the output of the
When the line 1 is connected, the output signal 38 of the detection section 36 is input to the decoding section 35 and the demultiplexing section 37 to switch the operation mode. This signal 38 is the OR gate 3
9 and becomes a signaling signal.

FIG. 7 is a time chart when modem data is sent from the encoder 2. The signaling signal input to the multiplexing section 32 consists of dial information and hook information as in the conventional case. However, when transmitting modem data, the multiplexer 32
Since the stealing of the hook information (via) is stopped, only the dial information is transmitted to the decoder 4 side.

Therefore, under the condition that the modem signal is being received, the detection unit 36 detects the signal 3.
8 to create a pseudo signaling signal.

When the transmission ends, a signaling signal (this time a hook-on signal) is sent from the transmitting side again, so the receiving side receives this and returns to the initial state when, for example, footer-on is detected three times as described above.

FIG. 8 is an overall view of FIG. 6, and the symbols of each part are the same as in FIG. 9.

〔Effect of the invention〕

As described above, according to the present invention, the focus steal is stopped or its cycle is extended during modem data transmission, so the error rate can be kept low even when high-speed modem data is transmitted. , high-quality transmission becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a block diagram of a specific example of FIG. 1, FIG. 3 is a time chart showing the operation of FIG. 2, and FIG. 4 is a block diagram of a specific example of the present invention. A configuration diagram of the second embodiment, FIG. 5 is a time chart showing its operation, FIG. 6 is a configuration diagram of the third embodiment of the present invention, FIG. 7 is a time chart showing its operation, and FIG. 8 is a time chart showing its operation. 6 is an overall diagram, FIG. 9 is a configuration diagram of a conventional ADPCH transmission system, and FIG. 10 is an explanatory diagram of an ADPCM code.

Claims (1)

[Claims] In a signaling transmission method in which a voice signal or a modem signal is encoded and a signaling signal having dial information for line selection and hook information for line maintenance is multiplexed and transmitted using an in-slot method, when transmitting a modem signal, the signaling signal is A signaling transmission method characterized by stopping multiplexing by bit stealing or lengthening its cycle.