JP2780630B2 - Signal multiplex transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal multiplex transmission system, and more particularly to a signal multiplex transmission system for transmitting an analog signal such as a voice signal together with an identification signal.

[0002]

2. Description of the Related Art Hitherto, a signal multiplexing transmission system has been known in which an analog signal (main signal) to be transmitted and auxiliary identification information (identification signal) are multiplexed and transmitted (for example, JP-A-1-175329). No., title of invention "optical transmission device"). This conventional system is a system in which a two-channel audio signal and a channel identification signal, which are analog signals, are converted into digital signals, and then time-division multiplexed signals are optically transmitted. The audio signal and the identification signal multiplexed in the assigned time slot are extracted.

According to this conventional method, since the identification signal generated based on the synchronization signal and the digital main signal (two-channel audio signal) are time-division multiplexed, the transmission side must be constituted entirely by digital circuits. The feature is that it can be done.

[0004]

However, in the above conventional method, the identification signal is time-division multiplexed with the main signal, so that a time slot for transmitting the identification signal is provided separately from the time slot of the main signal. Therefore, the transmission capacity that can be transmitted in a fixed time is small, and the presence of the main signal and the identification signal in different time slots causes the identification signal corresponding to the main signal to be confirmed. Takes a long time, and the circuit becomes complicated.

[0005] The present invention has been made in view of the above points,
It is an object of the present invention to provide a signal multiplex transmission system capable of transmitting an identification signal only in a time slot for transmitting a main signal.

[0006]

According to the present invention, in order to achieve the above object, one frequency obtained by frequency division multiplexing one main signal and one identification signal indicating identification information in transmission of the main signal is provided. A plurality of divided signals are generated by indicating each of a plurality of main signals and identification information in the transmission of the main signals, and combining each of a plurality of identification signals having different levels or frequencies from each other. A first multiplexing unit for performing time division multiplexing on each of the plurality of frequency division multiplexed signals extracted from the first multiplexing unit to generate one time division multiplexed signal and then outputting the generated signal to a transmission path Receiving the time-division multiplexed signal output from the second multiplexing means input through the transmission line, and
Separating means for separating into
A plurality of first filter circuits for separately frequency-selecting a plurality of main signals from the wavenumber division multiplexed signal, and separating means
A plurality of second filter circuits provided separately corresponding to the plurality of first filter circuits, wherein a plurality of identification signals are separately selected from the frequency division multiplexed signals extracted from the plurality of identification signals; The output signals of the second filter circuits are separately level-compared to determine the presence / absence of a plurality of identification signals independently of each other. A plurality of all separately provided corresponding to the plurality of first filter circuits are provided. A plurality of first signal output means for outputting the main signal output from the first filter circuit only when the identification signal is determined by the identification signal determining means provided corresponding to the first filter circuit; It comprises a plurality of selection output means provided separately corresponding to the filter circuits.

[0007]

According to the present invention, the main signal and the identification signal are frequency-division multiplexed by the first multiplexing means, then time-division multiplexed by the second multiplexing means, and the time-division multiplexed signal obtained by this is transmitted to the transmission line. Send out. Therefore, in the present invention, the main signal and the identification signal exist in the same time slot of the time division multiplexed signal to be transmitted, and the identification signal can be transmitted only in the time slot for transmitting the main signal.

[0008]

Next, an embodiment of the present invention will be described. FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a time chart of a main part of FIG. In FIG. 1, the first audio signal transmission system is provided with a suffix a, and the second audio signal transmission system is provided with a suffix b. In this embodiment, for example, the first and second audio signals A and B to be transmitted are analog audio signals such as a speech signal of a terminal device, respectively, and the first and second identification signals IDA and IDB are, for example, those of the device itself. It is a signal indicating an individual assignment number.

In FIG. 1, a first analog audio signal A
After being received by the audio signal receiver 1a, the band is limited to a predetermined frequency band by the bandpass filter 3a. On the other hand, the first identification signal IDA relating to the first analog audio signal A is supplied to the reference voltage generator 2a and is converted to a low frequency or DC reference voltage corresponding to the value, and thereafter is unnecessary by the low-pass filter 4a. High frequency components are removed.

Since the pass band of the bandpass filter 3a and the passband of the low-pass filter 4a are set so as not to overlap with each other, the first analog audio signal extracted from the bandpass filter 3a A and the first reference voltage corresponding to the first identification signal IDA extracted from the low-pass filter 4a are respectively frequency-division multiplexed, and then supplied to an A / D converter 5a to be subjected to analog-digital conversion. .

On the other hand, like the first analog audio signal A, the second analog audio signal B is received by the audio signal receiver 1b and then band-limited to a predetermined frequency band by the bandpass filter 3b. . Further, the second identification signal IDB relating to the second analog audio signal B is supplied to the reference voltage generator 2b, and a low frequency or DC second reference voltage having a different frequency or level from the first reference voltage. After the conversion, the unnecessary high frequency components are removed by the low-pass filter 4b.

Since the pass frequency band of the bandpass filter 3b and the passband of the low-pass filter 4b are set so that the frequency bands do not overlap like the bandpass filter 3a and the low-pass filter 4a, The second analog audio signal B extracted from the low-pass filter 4b and the second reference voltage corresponding to the second identification signal IDB extracted from the low-pass filter 4b are respectively frequency-division multiplexed, and then A / D converted. 5b for analog-digital conversion. The band filters 3a and 3b, the low-pass filters 4a and 4b, and their A / D converters 5a and 5b.
The signal lines up to the input terminal constitute the first multiplexing means.

The first digital signal extracted from the A / D converter 5a and the second digital signal extracted from the A / D converter 5b are supplied to a time-division multiplexing circuit 6, where they are predetermined. The time-division multiplexed signal is obtained by being multiplexed in the assigned time slot. A / D above
The converters 5a and 5b and the time-division multiplexing circuit 6 constitute the above-mentioned second multiplexing means.

The above time-division multiplexed signal is, for example, as shown in FIG.
FIG. In FIG. 2A, A is a time slot in which a digital signal of a frequency division multiplexed signal of the first analog audio signal A and a first reference voltage corresponding to the first identification signal IDA is multiplexed, and B is a time slot. This is a time slot in which the digital signal of the frequency division multiplexed signal of the second analog audio signal B and the second reference voltage corresponding to the second identification signal IDB is multiplexed.

The above time-division multiplexed signal is modulated by a transmission circuit (not shown) in a modulation method which can reproduce a clock suitable for transmission, and then transmitted to the transmission line 7. The modulated wave transmitted through the transmission path 7 is received and demodulated by a receiving circuit (not shown), and then input to D / A converters 8a and 8b and a timing extraction and generation circuit 9, respectively. The timing extraction and generation circuit 9 generates a timing pulse synchronized with the frame and clock of the received time-division multiplex signal, and supplies this to the D / A converters 8a and 8b. FIGS. 2B and 2C show a frame-synchronized pulse and a clock-synchronized timing pulse output from the timing extraction and generation circuit 9 respectively.

Thus, the D / A converters 8a and 8b
Respectively perform digital-to-analog conversion of the input time-division multiplex signal to separate and output the frequency-division multiplex signal . The analog signal output from the D / A converter 8a is input to the bandpass filter 10a and the low-pass filter 11a. Bandpass filter 10
a has the same pass band as the bandpass filter 3a,
The input analog signal (frequency division multiplexed signal) is limited to an audio band and supplied to an audio signal transmitter 18a.

The low-pass filter 11a has the same pass band as the low-pass filter 4a, selects a very low frequency and a DC component from the input frequency division multiplexed signal, and supplies them to the comparators 14a and 15a, respectively. . The comparator 14a compares the output signal potential of the low-pass filter 11a with a reference voltage A− supplied from the reference voltage generator 12a and having a level slightly lower than the first reference voltage. When the output signal potential of the filter 11a is higher than the reference voltage A-, a low level signal is output, and when the output signal potential is lower than the reference voltage A-, a high level signal is output.

The comparator 15a compares the output signal potential of the low-pass filter 11a with a reference voltage A + supplied from the reference voltage generator 13a and set at a level slightly higher than the first reference voltage. When the output signal potential of the low-pass filter 11a is higher than the reference voltage A +, a low-level signal is output. When the output signal potential is lower than the reference voltage A +, a high-level signal is output. Each output signal of the comparators 14a and 15a is supplied to a gate circuit 16a.

Thus, the gate circuit 16a outputs a high-level signal when the output signal potential of the low-pass filter 11a is within the level range between the reference voltages A− and A +,
When the level is lower than the reference voltage A− or higher than the reference voltage A +, a low level signal is output . Therefore, when the output signal of the gate circuit 16a is at a high level, it can be determined that the first reference voltage corresponding to the identification signal IDA has been input.

Therefore, the IDA receiving circuit 17a receives the output signal of the gate circuit 16a as an input signal, and when this input signal is at a high level, determines that the first reference voltage corresponding to the identification signal IDA is input. Then, the audio signal transmitter 18a is controlled to output the output signal of the bandpass filter 10a, and when the input signal is at the low level, it is determined that the input signal is not the first reference voltage corresponding to the identification signal IDA. Control is performed to stop the signal output of the audio signal transmitter 18a. Thereby, the audio signal transmitter 18a
Output only the first audio signal A.

On the other hand, an output analog signal (frequency division multiplexed signal) of the D / A converter 8b is input to the bandpass filter 10b and the low-pass filter 11b. Bandpass filter 10
b has a pass band similar to that of the bandpass filter 3b,
The input frequency division multiplexed signal is limited to an audio band and supplied to the audio signal transmitter 18b.

The low-pass filter 11b has the same pass band as the low-pass filter 4b, selects a very low frequency and a DC component from the input frequency division multiplexed signal, and supplies them to the comparators 14b and 15b, respectively. . The comparator 14b compares the output signal potential of the low-pass filter 11b with a reference voltage B− supplied from the reference voltage generator 12b and set at a level slightly lower than the second reference voltage. When the output signal potential of the filter 11b is higher than the reference voltage B-, a low level signal is output, and when the output signal potential is lower than the reference voltage B-, a high level signal is output.

The comparator 15b compares the output signal potential of the low-pass filter 11b with a reference voltage B + supplied from the reference voltage generator 13b and set at a level slightly higher than the second reference voltage. When the output signal potential of the low-pass filter 12b is higher than the reference voltage B +, a low-level signal is output. When the output signal potential is lower than the reference voltage B +, a high-level signal is output. Each output signal of the comparators 14b and 15b is supplied to the gate circuit 16b.

Thus, the gate circuit 16b outputs a high-level signal when the output signal potential of the low-pass filter 11b is within the level range between the reference voltages B− and B +,
When the level is lower than the reference voltage B− or higher than the reference voltage B +, a low level signal is output . Therefore, when the output signal of the gate circuit 16b is at a high level, it can be determined that the second reference voltage corresponding to the identification signal IDB has been input.

The IDA receiving circuit 17b receives the output signal of the gate circuit 16b as an input signal, and when this input signal is at a high level, determines that the second reference voltage corresponding to the identification signal IDB has been input. Then, the audio signal transmitter 18b is controlled to output the output signal of the bandpass filter 10b, and when the input signal is at a low level, it is determined that the input signal is not the second reference voltage corresponding to the identification signal IDB. Control is performed to stop the signal output of the audio signal transmitter 18a. Thereby, the audio signal transmitter 18b
Output only the second audio signal B.

As described above, according to the present embodiment, the time-division multiplexed signal to be transmitted does not require a time slot dedicated to the identification signal (reference voltage) as shown in FIG. Therefore, the transmission capacity per unit time can be increased as compared with the related art.

The present invention is not limited to the above embodiment. For example, the identification signal may be a signal in a frequency band different from that of the main signal to be transmitted. The signal may be a signal other than the audio signal. In the embodiment, the D / A converters 8a and 8b perform digital-to-analog conversion of the input signal regardless of the time slot, and selectively output only a predetermined audio signal from the audio signal transmitters 18a and 18b. However, for example, the operation of the timing extraction generation circuit 9 is controlled based on the output signals of the IDA reception circuits 17a and 17b, and only the signals of the desired time slots are input at the input sections of the D / A converters 8a and 8b. The digital-to-analog conversion may be performed after the extraction.

[0028]

As described above, according to the present invention,
By time division multiplexing the frequency division multiplexed signal of the identification signal to the main signal and transmitting the time division multiplexed signal, the identification signal is transmitted only in the time slot for transmitting the main signal. Therefore, when the present invention is applied to a wireless device, it is possible to effectively use the frequency.

[Brief description of the drawings]

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

FIG. 2 is a time chart of a main part of FIG.

[Explanation of symbols]

 1a, 1b Audio signal receiver 2a, 2b Reference voltage generator 3a, 3b, 10a, 10b Bandpass filter 4a, 4b, 11a, 11b Low-pass filter 6 Time division multiplexing circuit 12a, 12b, 13a, 13b Reference voltage generator 14a , 14b, 15a, 15b Comparator 17a IDA receiving circuit 17b IDB receiving circuit 18a, 18b Audio signal transmitter

Claims (1)

(57) [Claims] 1. A frequency-division multiplexed signal obtained by frequency-division-multiplexing one main signal and one identification signal indicating identification information in the transmission of the main signal is divided into a plurality of main signals and the main signal. A first multiplexing means for generating a plurality of sets each of which indicates identification information in the transmission of a plurality of identification signals having different levels or frequencies from each other; Second multiplexing means for generating a single time-division multiplexed signal by time-division multiplexing the plurality of frequency-division multiplexed signals extracted from the plurality of frequency-division multiplexed signals, and outputting the time-division multiplexed signal to a transmission path; Receiving the time-division multiplexed signal from the multiplexing means,
And a frequency division multiplexed signal extracted by the separation means.
And a plurality of first filter circuits for separately selecting the frequencies of the plurality of main signals , respectively, and the frequency division multiplexed signal extracted by the separation means.
A plurality of second filter circuits provided separately corresponding to the plurality of first filter circuits, wherein the plurality of second filter circuits are separately provided corresponding to the plurality of first filter circuits. A plurality of identification signal discriminating means provided separately corresponding to the plurality of first filter circuits, respectively, by separately comparing the levels of the output signals to determine the presence or absence of a plurality of identification signals. And outputting the main output signal of the first filter circuit only when an identification signal is determined by the identification signal determination means provided corresponding to the first filter circuit. A signal multiplexing transmission system comprising a plurality of selection output means provided separately corresponding to a filter circuit.