JPH0222937A - Method and apparatus for transmitting signals from plurality of information channels through single transmission channel - Google Patents

Abstract

PURPOSE: To reduce frequencies, and to improve transmission reliability by transmitting a signal from plural information channels through a single transmission path by a common coding method. CONSTITUTION: A coder 16 encodes a parallel 4 bit group successively received from four A/D converters 14 into a corresponding quadrature amplitude modulation(QAM) code signal. A code word sequence expressed and coded by this common code word is transmitted through a single information channel 18, the trans-mitted code word sequence is decoded by a decoder 20, and plural code units transmitted by using the decoded code word are re-constituted. Then, the re-constituted code units are supplied to corresponding information channels at a receiving side. Thus, frequencies can be reduced, and transmission reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to transmitting information from a plurality of information channels via a single transmission path, and more particularly relates to transmitting information from a plurality of information channels via a single transmission path, and more particularly, to It concerns the transmission of channels.

(Prior Art) U.S. Pat. No. 4,675,721, cited herein, describes a method for encoding and transmitting television signals, in which code elements consist of a half period or period of sinusoidal vibration. A format is used in which the magnitude of the amplitude represents the binary values 1 and 0, respectively.

The code elements of this coded color television signal oscillate in a manner similar to a continuous sine wave. Pairs of vibrations of this type having a phase difference of 90 degrees can be superimposed, and the superimposed composite waves can be transmitted in the form of alternating current at each frequency.

U.S. Pat. No. 4,794,621, also cited, describes a system for transmitting information by negative modulation,
The system uses a method in which the phase angle of the electrical oscillations is changed incrementally in response to the modulation signal to avoid extremely sudden phase transitions. This US patent specification further describes the use of ordinary PSK (Phase Shift Keying).
A special circuit for performing a step phase shift is also disclosed, which is different from the 5hift Keying) circuit and which can be used in the practice of the present invention as described below.

Also cited in U.S. Pat. No. 3,887,768 is the use of a 16-value code alphabet represented by an oscillating signal that can assume four different amplitude values and eight different phase values. A featured quadrature amplitude modulation (QAM) method is described.

Five frequency multiplexing and time multiplexing methods for transmitting multiple signals or information channels over a single transmission channel are well known. In frequency multiplexing, information signals to be transmitted simultaneously are converted into different frequency ranges,
A carrier wave having a higher frequency is then modulated with the converted signal. In time multiplexing methods, the information signals to be signaled are sampled and the resulting samples of different information signals are combined with each other and transmitted sequentially; these methods have been used for a long time. Therefore, further detailed explanation will be omitted.

The invention is based on the problem of providing a new method and means for transmitting multiple information signals via a single transmission channel, which is characterized by low frequency requirements and high transmission reliability.

SUMMARY OF THE INVENTION The method according to the invention requires mutually synchronized digital information signals. If the information signal to be transmitted is not already a digital signal, it is digitized in the usual way using sampling. Sampling of the information signal is conveniently done synchronously so that the information signal is later provided in the required synchronized digital form.

If the information signals are already in digitized form or arrive asynchronously with respect to each other, they may be synchronized by buffering and reading out synchronously, or by any other suitable means.

Now, according to the invention, code signals coming from different input channels and occurring simultaneously in the rhythm of the synchronization process
An entity is encoded by a single code character or code word of a multivalued code alphabet (as opposed to a binary code alphabet, which can only represent the two values O and 1) and then - Words are transmitted via a transmission channel.

At the receiving end, this code word is decoded to obtain the code entities of the output signal of each signal channel, corresponding to the input code entities encoded and transmitted in the form of a code word. This code entity may be a code element (part of a code word), such as a bit of a binary code word, or a complete input code word or a portion thereof (two or more code words). elements), combinations of code words and parts of code words and/or code elements.

The encoding is, for example, the quadrature modulation mentioned above.
This can be done by any suitable well-known encoding method. Preferably, this encoding is done in such a way that it is possible to detect the absence of an input signal value in the information channel; in the case of asynchronous input information, the information signal is present at a certain clock or synchronous point in time. It may not even exist.

This invention applies to telex signals, teletext signals, telefax signals, telephone signals, and data signals.

It can be used for multiplex transmission of television signals, radio, ISDN systems, etc.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus shown in FIG.
, C, and D through one transmission channel.

The device comprises four analog/digital (A/D) converters 14 arranged in groups, each having an input to which one of the telephone channels A to D is connected;
a coder 16 having four inputs connected to each output of a D-converter 14; coder 16 having an output coupled to an input of a transmission line 18; The output of transmission line 18 is coupled to a decoder 20 having four outputs, each output of decoder 20 being connected to the input of one of four buffers 22. The output of the buffer 22 is connected to a corresponding digital/analog (D/A) converter 24.
The output of each D/A converter 24 has four receiving television channels A'B', C
' and D' are connected.

Each A/D converter 14 converts an analog telephone signal into a
, ooo times, and this sampling is controlled by a clock generator (not shown). Each A/D converter 14 transfers the resulting digitized samples to a coder 1.
6 to corresponding inputs. In the embodiment of FIG.
The /D converter provides a digital serial 8-bit output signal for the samples. The coder 16 in the embodiment of FIG.
M coder・The coater 16 has four A/D converters 1
QAM corresponding to groups of parallel 4 bits received one after another from 4
Code into a code signal. This QAM code signal is supplied to the transmission line 18. Transmission line 18 may be simply a line or may include any desired suitable transmitting and receiving equipment, including any carrier frequency equipment, multiplexing equipment, high frequency transmitting and receiving equipment, and the like.

The decoder 20 is a QAM decoder, and its four outputs are
A parallel 4-bit output signal is generated corresponding to the 4 bits at the input of the coater. In the buffer 2z, each 6 bits belonging to a predefined digital sample are buffered. Once all bits of one sample have been stored, these bits are converted into corresponding analog signals by corresponding D/A converters. The analog signal is passed through a low pass filter (not shown) and provided to the corresponding receiving telephone channel in the conventional manner.

Next, referring to FIG. 2, it will be explained in detail how the digitized samples provided by the A/D converter are encoded by the coater 16. Each of the converted samples is represented serially by eight bits. As is clear from FIG. 2, at time t1, bit 1110 corresponding to decimal 14 appears at the input of the coater. Therefore, coater 16 has 14 of its code alphabet.
Generates a signal corresponding to the th "letter" (word, character).

At time t2, bit 0100 is present at the input of coater 16, which corresponds to decimal 4. Therefore,
The coater provides a signal corresponding to the fourth letter of the code alphabet.

In this way, all 8 bits of the 4 initial samples from the 4 channels are converted. On the receiving side, the 8 bits of each sample are temporarily buffered (-time stored), and when all 8 bits of a sample are present, these 8 bits are matched by the corresponding D/A converter. is converted to an analog value. If the starting points of the code transmission packets are synchronized, ie clocked, there is no need for spacing between successive code words.

The apparatus of FIG. 1 is capable of handling analog signals other than telephone signals, e.g.
It can also be used to transmit television signals. In this case, for example, channels A and B can send a luminance signal, channel C can alternately send two color signals, eg, ■ and Q signals, and channel D can send synchronization and audio signals. Since the bandwidth of luminance signals is considerably wider than that of other signals, in order to transmit television signals it is better to modify the apparatus shown in Figure 1 to the form shown in Figure 2. good.

The device shown in FIG. 3 has inputs for the luminance signal, for the color signals I and Q, for the synchronization signal and any other signal S, and for the audio signal T.

The L input is connected to an 8-bit A/D converter 14L, which performs A/D conversion! The output of 114 is connected to a first input of coater 16. This coater 16 requires only three inputs and therefore operates with an eight-value code alphabet. ■ and Q inputs are the first time multiplexer 3
0 input and the output of time multiplexer 30 is another 8-bit A/D conversion! ! 141Q to a second input of coder 16.

The S and T inputs are connected to a second time multiplexer 3 whose output is
The output of multiplexer 32 is coupled to a third input of coater 16 through a third 8-bit A/D converter 14ST. The output of the coater 16 is coupled to the input of a decoder 20 through a transmission line I8, and a digital luminance signal L' is output to the first output of the two decoders. The second output of the decoder is
is coupled to a demultiplexer 34 at the output of which digital 1' and Q' signals appear. Decoder 2
The third output of 0 is connected to a second demultiplexer 36, at the output of which a digital synchronization signal (and other transmitted signals) S' and a digital audio signal T' are obtained. . These digital signals are further digitally processed in one conventional manner as is customary in television technology and/or converted into corresponding analog signals.

FIG. 4 shows an apparatus according to the invention for transmitting telex signals from four different telex channels. Since normally telex signals are not synchronized with other telex signals in different telex channels, FIG. In the device shown in Figure 1, the telex signals are processed to synchronize them with each other before being fed to the coder.

The device in Figure 4 is a four-channel system for four telex channels.
It has three input terminals A, B, C, and D. These input terminals have corresponding buffers 40A, 40B, 4
Coupled to 0C140D. Buffer 40A~40
The output of D is connected to the corresponding input of the decoder 16,
The output of decoder 16 is coupled to the input of coder 20 via transmission line 18. Buffers 40A-110D and coder 16 are coupled to clock generator 42.

The apparatus of FIG. 4 operates as follows.

Telex signals arriving asynchronously at input terminals A-D are temporarily buffered in corresponding buffers 40A-40D, read out synchronously by a clock signal from clock generator 42, It is encoded synchronously by a controlled coder 16.

The encoding, transmission and decoding in the apparatus shown in FIGS. 3 and 4 takes place in the manner described with reference to FIGS. 1 and 2.

FIG. 5 shows one particularly effective encoding method.

The encoding method shown in FIG.
No. 675,721, it takes the form of a period or half-period of sinusoidal oscillation, and the binary values 0 and l are determined by the small and large amplitudes of the period or half-period of sinusoidal oscillation, respectively. It operates on binary code elements as shown. In Figure 5, the code elements are:
Consisting of alternating positive and negative half-cycles of sinusoidal vibration, the half-cycles of relatively small amplitude represent the binary value O, and the half-cycles of relatively large amplitude represent the binary value 1. There is.

The code shown in FIG. 5 can represent a nine-digit binary number. This is done as follows, 9 to be coded
The bits in the first and second digits of the binary number are the fifth
It is represented by a first positive half waveform 1 of sinusoidal vibration having a period length P as shown in waveform a in the figure, followed by a second negative half waveform 2.

3.4 and 5fff of the 9 digit binary numbers to be encoded
The bit in the second digit is 1 as shown in the waveform in Figure 5.
It is represented by a continuous half waveform of sine wave vibration with a period length of 2P/3. Also, the 6th, 7.8th, and 9th digit bits of the 9-digit binary number are as shown in wave @C in Figure 5.
It is represented by a continuous half-waveform of sinusoidal vibration with a period length of P/2. For ease of explanation, the sinusoidal oscillations represented by waveforms a, b, and c are shown as having the same amplitude in the first period pt and thus representing a coded binary number consisting of nine 1's. has been done.

Subsequent periods P2, P3. . . ., the following 9-digit binary number is encoded in the same way. In waveform a, the value 00 is shown in one period P2, and the value 1 is shown in period P3.
0 is shown.

Code waveforms or vibrations created by encoding corresponding to waveforms a, b and C are additively superimposed on each other,
It can then be transmitted via a single line or other transmission channel. At the receiving end of vibrations a, b and C, a
, bj5 and C are separated by a filter and can be decoded by known methods, e.g., by measuring the duration of each half-period, as described in U.S. Pat. No. 4,794,621. can.

The encoding method described with reference to FIG. 5 has various variations. To create different period lengths of oscillation for the encoding of successive bits, the total number of code elements (one period or half period of sinusoidal oscillation) is used as the encoding of the character. It is sufficient if it falls within period P.

Therefore, it is necessary that a large number of coded vibrations a, b, c, . . . always have the same phase position at the beginning and end of each coding period. duobinary (duob 1na)
ry) If amplitude steps (=3 different amplitude levels) are used instead of the two amplitude level configuration shown in FIG. 5, 39 combinations are possible. Another possibility is that by superimposing this type of code waveform with a 90" phase shift, 31"
A combination of f' is obtained. Duobinary encoding method, for example.

Used in the European D-MAC system.
The coded vigor of the method shown in FIG.
. It can be increased by Two oscillations with the same period length and quadrature relationship, e.g. waveforms a and a'
are superimposed, and the resultant vibration a'' has the same period length as the superimposed lateral vibrations, so it can be separated by a filter and decomposed into component vibrations by a synchronous modulator on the receiving side. Applying the method described with reference to FIG. 5, 18 binary characters can be transmitted during the coding period P.

The encoding method shown in FIG. 6 operates on code characters in the form of one period of sinusoidal oscillation. For encoding, the period length P and the amplitude of the half-waveform are used. In the embodiment of FIG. 6, two separate period lengths PI and 22 and 2
Only two separate amplitudes AI and A2 are shown. Of course,
Three or more different discrete period lengths and/or three or more different discrete amplitude values may be used, in which case the range of code character variation increases accordingly.

The coding scheme of FIG. 6 with two separate period lengths Pl and R2 and two separate amplitude values AI and A2 gives an 8-digit code. In FIG. 6, eight different code characters a, b, c, . . . h are shown.

Decoding of code elements with different period lengths is preferably carried out by measuring the period length according to the method shown in U.S. Pat. No. 4,794,621, using half periods of two amplitude values and two durations. and 42
Using three amplitude levels yields 16 combinations corresponding to a 4-bit binary number:
Thirty-six combinations are obtained. However, the number of combinations is
Preferably, this is increased by increasing the number of different wave period lengths. For example, there are the following combinations:

For 3 half-waveforms and 2 amplitude levels, 2 digits, 62=
: 16 combinations, 3 digits, 63 = 216 combinations, 4 digits, 6' = +296 combinations, 5 digits, 6' = 7776 combinations (this corresponds to a binary number of 12 bits or more) ).

For 4 half waveforms and 2 amplitude levels.

2 digits, the combination 82=64; 3 digits, the combination 83=512; 4 digits, the combination 8'1096 (this corresponds to a 12-bit number).

FIG. 7a shows different period length stages; periods of different period lengths can be easily distinguished by the detection method of measuring the period length. That is, if 1, the phase shift amount θ° is set so that the distances between b and a and a and 2 are substantially equal. ,b@
In FIG. 7, a phase shift of 90 degrees or more is provided, but the disadvantage is that the frequency change is large. If the signal does not contain a DC component.

Each code element must be given one full period.

Preferably, the different period lengths are generated using the circuit shown in FIG. 1O and described below.

Figure 8 shows a circuit capable of creating code characters with four different amplitudes. The circuit of Figure 8 is connected to the input of each switch Sl, S2, S3 and S4 through four parallel branches. The output of each switch is connected to a common output terminal 82, having an input terminal 80. Each of the three trees in the parallel branch includes resistors R1, R2 and R3. The fourth branch line does not include an independent resistance.

Input terminal 80 is also connected to the input of switch control circuit 86 via limiter 84 . Switch control circuit 8
In addition to this, S is equipped with a 0-to signal input 88,
It also has four outputs connected to each of the control inputs of the switches Sl to S4.

The circuit configuration shown in FIG. 8 operates as follows.

A code signal vibration with maximum amplitude is supplied to input terminal 8G. This vibration is, for example, the vibration of a continuous code element consisting of several cycles of a sine wave or a half-waveform. This vibration is transmitted through the four parallel branch lines to the switch 5l-
Sent to input of S4.

A signal of the required amplitude at the output terminal 82 causes the switch 81 to be activated under the control of the code supplied to the code input.
~S4 is closed. The closing of the switches is synchronized by the output signal of limiter 84. For example, when switch S4 is closed, a code element of maximum amplitude occurs at output terminal 82. Resistors R1, R2 and R3 connect switches S1. Values that differ by one step are given so that the required amplitude appears at the output terminal 82 when S2 and S3 are closed.

In the circuit of FIG. 8, a relatively large number of different amplitudes can be obtained by appropriately selecting the resistance values and closing two or more switches.

FIG. 9 shows a part of a television receiver, in which an antenna terminal 90, a high frequency amplifier 92, an oscillation mixing stage 94, an intermediate frequency amplifier g6 and a wave detector g8 are connected in this order. These circuits have a conventional configuration. A decoder 916 is connected to the output of the detector 98, which decoders 916 for each of the blanking and synchronization signals AS, the luminance signal Y, the color signals R and B, the audio signal T and the special signal SO. It has an output. The color signal output is connected to a matrix circuit 100, and the output of this matrix circuit 100 includes color difference signals R-Y, G-Y.
and BY are obtained. These signals are then further processed in known manner.

The circuit shown in FIG. 10 includes an oscillator 9200 that provides an oscillating wave fA to the encoder 202, which is also supplied with another information signal through an input 204, through an output signal of the 0 oscillator 200 and a gate 206. It is also supplied to a shift register 208 which acts as a counter.

Shift register 208 has outputs 21 and z2.

Coder 202 has phase control outputs g2 and g3, which are coupled to one input of AND gates 210 and 212, respectively. The other input of the AND gate is coupled to outputs Zl and Z2 of shift register 208, respectively. The outputs of AND gates 210 and 212 are connected to electronic relay 214. Start signal B is AND
A second input of gate 206 is provided. This signal B is generated at the beginning of the transmission and is held during the transmission. The electronic relay 214 has two inputs 216 for positive and negative DC voltages and an output 218 at which a rectangular oscillating wave appears. This rectangular oscillation wave is converted by a low-pass filter 220 into a signal having at least a substantially sinusoidal shape,
The signal is supplied to a transmission line, such as a lead wire 226, via a transformer 222 and a filter 224. In the circuit of FIG. 10, various amplitude states can be created as follows. That is, a multi-pole relay is used, to which a corresponding number of different positive and negative voltages are applied. or,
An amplitude modulator may be connected between relay 214 and low pass filter 220.

To simplify the explanation, the two code outputs g2 and g3
Although only two AND gates 210 and 212 are shown, in reality, as the number of phase changes in the directions of one phase lead and phase lag increases, the same number of similar circuit elements are provided.

In operation, the coder 202, for example,
Enabling the ND gate 212 causes the electronic relay 214 to receive a switch pulse as soon as the shift register 208, acting as a counter, has counted up to the step specifying the output Zl. At the same time, a reset signal R is generated by gate 228.

When the shift register 208 next reaches the output Zl, the electronic relay 214 is switched again and the rectangular output oscillation wave 2
30 is generated. The period of this rectangular output oscillation wave 230 is determined by the state of the output Zl. By lengthening or shortening this period, it is possible to insert any desired phase state; The various outputs of shift register 208 z1, Z2,
This can be easily done by using the output signals of .

FIG. 11 shows luminance signals and color signals I and Q.
, a circuit according to the invention for encoding a color television signal comprising a synchronization signal (and, if necessary, additional signals) S and an audio signal T. The luminance signal is sampled at a predetermined frequency, and an analog-to-digital (
A/D) converter 101. The soot elements (bits) of the code word are transferred into memory 103. Color signals I and Q are simultaneously sampled at a frequency equal to half the sampling frequency of the luminance signal, and the resulting samples are stored in intermediate memory 105. The stored signals I and Q are transferred to the selector switch 10.
7 to the A/D converter 109 alternately. A
/D converter 109 provides a 6-bit code word, which is stored in memory 103. Synchronization signals and other signals, if any, are added,
S.

are alternately or simultaneously sampled together with the audio signal T (for example, a stereo audio signal, audio in different languages, etc.) at a suitable frequency, stored in an intermediate memory 111, and supplied to an A/D converter 115 through a changeover switch 113. A
/D conversion@115 provides 8-bit or 16-bit code words, which are also stored in memory 103. A coder 117 is supplied to 10 memories. The coder 117 simultaneously, i.e. in parallel, outputs 8 code elements (bits) of each luminance signal sample and 3 code elements of I or Q@ via changeover switches Ul, 02, U3, and S Or one code of T signal.

element (see column I in Figure 12)・12th
In the figure, the longer line represents the binary digit 0, and the shorter line represents the binary digit 1. These 12 bits are processed by coder 113 into a single code word or code code, preferably as shown and described in FIGS.
converted to a character. A code character (word) made from the bits shown in columns I to ■ in Figure @12 is supplied to a conventional high frequency transmitter 119 to modulate a high frequency signal, and the modulated high frequency signal is transmitted through an antenna 121. Ru. On the receiving side, the above-mentioned high frequency signal is received by an antenna 123 and a conventional receiver unit 1
25 and demodulated. The demodulated code signal is supplied to the decoder 127 as described with reference to FIG. The code word is decoded by the decoder 127, and the code word is decoded by the decoder 127 and output to the first output terminal group 1 consisting of eight output terminals.
At the same time, 8 bits of consecutive samples of the luminance signal are generated. Three color signal bits also appear in the group 131 of three output terminals, and these three bits are stored in the intermediate memory 133. Furthermore, the bits of the signals S and T appear alternately at the output terminal 135, and these bits are temporarily stored in the memory 137. Each group of 8 bits of luminance signal is D/
The A converter 139 converts the signal into an analog luminance signal level L. The color signal bits are sequentially stored in the memory 133, and when the 6 bits of the signal sample and the 6 bits of the Q signal sample are complete, the completed color signal code word is converted into an analog color signal by the D/A converter 141. , are stored in the analog signal storage device 143 and supplied to the corresponding output terminals ① and Q, respectively.

The S/T bits are stored in intermediate memory 145 and, once a complete code word is formed, converted to a corresponding analog signal by D/A converter 137. This analog signal may be stored, for example, in analog signal storage 149, or may be immediately subjected to other necessary processing in the television set, as usual. During the blanking period of the television signal, another code signal X is transmitted through the switch 151 4
11119 can be supplied. On the receiving side, these additional code signals appear at the output terminal AT of the decoder 127, from which they are extracted and used.

#! Figure 13 shows an example of a simple JPSK encoding method (four-phase shift keying encoding method), where f represents the regular frequency corresponding to the regular period length of 360°. A phase shift of 135° gives a phase of 405” or a phase shift of 135° gives a 49” phase.
With a phase of 5° and a phase shift of -45”, 315
With a phase of 135° and a phase shift of 135°, 2
This is performed by setting a phase of 25°. Each of these phases has a frequency f1. f2, f3 and f4
corresponds to

A circuit of the type shown in FIG. 14 is useful for performing phase keying as described above.

The circuit of Figure 14 has 360
an oscillator 301 which generates output pulses for the oscillator 301 and a counter 303 to which the pulses from this oscillator 301 are fed through an AND gate 302, each having two input terminals, one of which is connected to the phase control unit 315 of the other. AND gates 305 , 307 whose input terminals are coupled to corresponding ones of five different output terminals of counter 303
, 309, 311 and 313 is controlled by the code input signal CE and enables the AND gates 305-313 corresponding to the desired phase shift. Furthermore, unit 3
15 provides a start signal B that enables AND gate 302 during the transmission period. AND gates 305-31
The output of 3 is fed to an OR gate 317 whose output is connected to the switchover input of flip 70 tube 319. flip flop 31
9 is supplied with the start signal B to its enable power. The output of the OR gate 317 is further supplied to the reset input terminal RS of the counter 303. In order to perform the 4SPK encoding method shown in FIG. An output terminal is provided which is coupled to the input of .about.313.

The circuit of FIG. 14 operates as follows. The zero oscillator 301 generates one pulse for every degree of phase angle.

Phase control unit 315 enables AND gate 302 and counter 303 to begin counting at the beginning of each transmission. Additionally, the 0 phase control unit 315, in which the start signal B enables the flip-flop 319, is controlled by the code input signal CE to control the AND gate 30.
5 to 313 corresponding to the required cycle length. Once the desired phase angle, e.g. 315°, is obtained, flip-flop 319 switches to the enabled AN
The pulse is received through the D gate and the OR gate 317 and the state changes. In this way, the output of flip-flop 319 produces a signal of the type shown in FIG.

If the transmission is synchronized, the normal period length 360
Output at ° is not required.

In addition to the information conveyed by the period length, two or three amplitude levels may be provided by the electronic relay 214 shown in FIG. 1O; thus, with two amplitude levels and four period lengths, 82=64 combinations are possible,
Using four amplitude levels and four period lengths, we obtain 4096 sets corresponding to 12-bit binary numbers.

FIG. 15 schematically shows a coding method for narrowband information transmission; It consists of a predetermined period Tc. If the code is a binary code, bits l and 0 are represented by two different amplitude levels of alternating current, A1 and Ak. The transition between the amplitudes A, and Ak is shown by the period U in FIG.
This is performed continuously within the element period Tc. If code elements of the same value follow, the amplitude does not change,
Therefore, if five consecutive code elements have the same value, waves of the same amplitude will be transmitted for a period of 5×Te. The coded alternating current may be of a sufficiently high frequency for direct wireless transmission, or
It may also be used to modulate a suitable carrier wave.

Although two amplitude levels are shown in FIG. 15, this encoding method is not limited to this, and three or more different amplitude levels can also be used. With three amplitude levels, a duobinary code is obtained, and with four amplitude levels, a quaternary code, etc. is obtained. Furthermore, as described with respect to FIG. 5a, the code waveform can then be combined with a code waveform of the same type with a phase difference of 90'', in which case a quaternary code is obtained with l code elements.

In order to insert a narrowband code signal between the first television channel and the subsequent higher frequency television channel, a filter means in series with a Nyquist slope (Nyquist 5lope) in the transmitter is used. A resonant circuit (notch filter circuit) is provided. This series resonant circuit suppresses the television signal of the first lower channel in a relatively narrow frequency band, as shown by RR in FIG. 16, and the code wave shown in FIG. is inserted into a narrow frequency band from which the John signal is removed.

A television circuit for this purpose is shown in FIG.

The circuit includes a conventional television transmitter 600 including a Nyquist gradient filter 600a; the output of the television transmitter 600 is passed through a notch filter circuit 602, such as a series resonant circuit, to a signal combining circuit 604.
A second input of the zero combination circuit 604 coupled to a first input of the code waveform T, as shown in FIG.
Receive.

According to another aspect of the invention, which can be used alone or in combination with the various features described above, two or more separate information code words are combined into one Can be encoded as a code word.

For telex signals, the code word consists of five current periods. A telex code word therefore corresponds to a 5-bit binary number. two telex
Coding the code words into one common composite code word results in the use of a code alphabet with at least 210 different code words. Of course, this aspect is not limited to telex signals.

The invention is not limited to the preferred embodiments, signals and applications described above; various modifications will occur to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a first embodiment of a transmission system according to the present invention, and FIG. 2 is a diagram for explaining the mode of operation of the system of FIG. 1. 3 and 4 are block circuit diagrams of different embodiments of the invention, and FIGS. 5 to 7 are diagrams for explaining useful encoding methods according to the invention. FIG. 8 is a block diagram of a useful coder. 9 is a simplified block diagram of a portion of a television receiver operated by the method according to the invention; FIG. 1O is a block diagram of a phase shift circuit; and FIG. 11 is a circuit for encoding a color television signal. FIG. 12 is a diagram illustrating the principle of the recommended method for encoding color television signals. FIG. 13 is a PSK code signal waveform diagram, FIG. 14 is a block diagram of a phase shift circuit, and FIG. 15 is a diagram showing the waveform of a certain code signal. FIG. 16 is a diagram showing a television signal to which the code signal shown in FIG. 15 is added, and FIG. 17 is a block diagram of a television transmitter used with the code signal shown in FIG. 15. 16...Coder, 18...Single transmission channel, 20...Decoder.

Claims (30)

[Claims] (1) A method for transmitting a plurality of digital signals, each consisting of a sequence of code units, from a plurality of information channels through a single transmission channel, the method comprising: representing and encoding said plurality of substantially simultaneously occurring code unit sequences by a common code word such that a word sequence is generated; transmitting over a channel; decoding the transmitted code word sequence and using the decoded code words to reconstruct the transmitted plurality of code units; and providing said reconstructed code unit to a corresponding information channel of a receiver. 2. The method of claim 1, wherein the code units of at least one information channel are complete code characters of a multivalued code alphabet. 3. A method as claimed in claim 1, wherein the code units of at least one information channel consist of a portion of code characters of a multilevel code alphabet. 4. The method of claim 2, wherein the code characters are binary numbers having more than one digit. 5. The method of claim 3, wherein the code characters are binary numbers having more than one bit, and each of said portions consists of at least one bit. 6. The method of claim 1, wherein the code word is a QAM code alphabet. (7) Each code word contains one period of a predetermined length.
two half-wave parts with alternating polarity of a sinusoidal wave;
A combination consisting of at least one further sinusoidal wave superimposed on these two half-wave parts and comprising an integer number of half-wave parts of alternating polarity within said period length and having the value 0 at the beginning and at the end of this period. 2. A method as claimed in claim 1, characterized in that the wave is a wave, and each of said half-wave parts is adapted to assume at least two different amplitude levels. (8) Claim (8) wherein said composite wave is combined with a second composite wave of the same type, and these composite waves have a phase difference of 90°.
7). (9) The code word includes code elements each consisting of a plurality of periods of a sine wave, different values of the code elements being represented by different amplitude levels, and a first value of a predetermined value. If a code element is followed by a second code element of a different value, one of said code elements causes the amplitude of the wave to change continuously from the value of the first code element to the value of the next code element. A method as claimed in claim 1, characterized in that the code elements form a continuous code signal wave. 10. The method of claim 9, wherein the code signal wave is combined with a second code signal wave of a second type, the signal waves having a phase difference of 90°. 11. The method of claim 9, wherein the code signal wave represents a sequence of interlaced information signals. (12) the code signal wave has a frequency in a frequency range between a first television channel in a predetermined television frequency band and a second television channel following the television frequency band; 10. A method as claimed in claim 9, wherein the narrow part of the frequency range is substantially free of television signals and the code signal wave is transmitted in the narrow part of the frequency range. (13) An additional signal between a television signal of a first television channel in a certain television frequency band and a subsequent television signal of a second television channel having a higher frequency than the first channel. an apparatus for transmitting a television signal, comprising: filter means for generating a Nyquist slope of a television signal of said first television channel; and filter means for suppressing a television signal within a narrow frequency range between said two channels. a notch filter circuit and means for inserting a wave within said narrow frequency range, wherein said inserted wave is such that each code element of the code word comprises a plurality of periods of a sine wave;
Different values of the element are represented by different amplitude levels,
If a first code element of a certain predetermined value is followed by a second code element of a different value, one of said code elements causes the wave amplitude to change from the value of the first code element to the next code element. The device as described above is a continuous code signal wave formed by code elements adapted to include a continuously varying transition region to a value of . (14) said code word comprises a code element consisting of a period of a sinusoidal wave, said period consisting of two half-wave parts, each half-wave part having at least two different amplitude levels; 2. A method as claimed in claim 1, in which the period has a length which is adapted to assume at least two different values. (15) at least two code words such that each code word assumes at least two different amplitude levels;
2. A method according to claim 1, wherein the method consists of an element. 16. The method of claim 15, wherein said code element is a half-wave portion of a continuous sinusoidal code wave. 17. The method of claim 15, wherein the code elements are comprised of periods of continuous sinusoidal code waves. 18. The method of claim 1, wherein the code word is capable of assuming at least two different levels of at least one of its amplitude and phase parameters. (19) A method of transmitting a digital signal of at least one information channel consisting of a sequence of code words, wherein at least two consecutive code words are coded together to form a common composite code word. A method characterized by: (20) Apparatus for transmitting a television signal including a luminance signal, first and second color signals, a synchronization signal, and an audio signal through a single transmission channel, the apparatus having an input for receiving an analog luminance signal; a first A/D converter means having an output for generating a sequence of digital luminance signal samples; and two input terminals receiving the first and second color signals; a first multiplexer means having an output coupled to the output of the first multiplexer means and an output for generating a sequence of alternating first and second color signal samples; a second A/D converter means having an output for generating a sequence of signals, two inputs receiving said synchronization signal and an audio signal, respectively, and a second A/D converter means for generating alternating samples of the synchronization signal and the audio signal; a third A having an input coupled to the output of said second multiplexer means and an output for generating a sequence of alternating digital synchronization signals and audio signal samples;
the A/D converter means; three inputs coupled to the outputs of the first to third A/D converter means; and an output coupled to a transmission line; a coder adapted to convert simultaneously occurring code units of said digital samples from said D-converter means into a single code word and supply said output to said transmission line;・
a decoder that decodes the code word by generating a carried code unit from the code word and provides the code unit to a luminance signal output, a color signal output and a synchronization signal/audio signal output; means, an input coupled to the color signal output of the decoder means, and code units of said first and second color signals respectively appearing separately. a first demultiplexer having a first and a second output; an input coupled to the synchronization signal/audio signal output of the decoder means; a code unit for the synchronization signal and a code unit for the audio signal; an apparatus for transmitting a television signal through a single transmission channel, the apparatus comprising: a second demultiplexer having first and second outputs in which the signals are separately appeared; (21) Apparatus for transmitting a plurality of digital signals each consisting of a sequence of code units from a plurality of information channels via a single transmission channel, the apparatus comprising: a simultaneous set of code units from said information channels; coder means having input means for each information channel for receiving and being coupled to the transmission channel and producing at output one code word for each set of simultaneous code units; and an input adapted to be coupled to said transmission channel;
decoder means having a number of outputs equal to the number of information channels and producing for each code word received a corresponding number of code units at said output which is coupled to the corresponding information channel of the receiver; A device comprising: and. (22) means for synchronizing said plurality of information signals between said information channel and said plurality of inputs of said coder means in response to said plurality of digital signals from said plurality of information channels being received asynchronously; 22. The device according to claim 21, comprising: (23) The coder includes a shift register having an oscillator for generating a clock signal, an input coupled to the output of the oscillator, and a plurality of outputs each for generating an output signal with a different count value; a plurality of gates having first inputs coupled to corresponding outputs of the shift registers, and an input signal coupled to second inputs of the plurality of gates and controlling the time of a half period of the output code wave. control means for responsively enabling one of said gates; and electronic switching means coupled to an output of said gate for generating an output wave having a half period of time determined by said control signal. 22. The device according to claim 21, wherein the device is 24. The apparatus of claim 23, wherein said electronic switching means includes means for generating different amplitude levels of said half-waves of said output code wave. (25) An apparatus for transmitting a television signal including a luminance signal, first and second color signals, a synchronization signal, and an audio signal, the apparatus comprising: an input receiving an analog luminance signal;
a first having an output for providing luminance signal samples;
A/D converter means having first and second inputs and first and second outputs for said first and second color signals, respectively, and storing signal samples of said color signals. a first memory for providing a first selection switch; a first selection switch means having two inputs coupled to an output of the first memory; and an output coupled to an output of the first selection switch means; second A/D converter means having an input and an output; a first input for receiving the synchronization signal; a second input for receiving the audio signal; and two outputs; a second memory storing signal samples of and supplying said signal samples to said two outputs; a second memory having two inputs coupled to said two outputs of said second memory; and an output. a second A/D converter means having an input coupled to the output of the second selection switch means and an output; - a first group of output terminals for storing color signal samples and alternating digital sync/audio signal samples, in which code elements of successive digital luminance signal samples appear in parallel; an intermediate memory having a second group of output terminals at which code elements of said digital color signal sample appear and an output at which said synchronization and audio signal sample bits appear; coupled to said first group of output terminals of said intermediate memory; has been
a selection switch for a first group of input terminals receiving in parallel the bits of each digital luminance signal sample and a pair of output terminals of said intermediate memory, each of which receives bits of said first and second color signal samples; coder means having a second group of inputs coupled via a second group of inputs and an output terminal coupled to said synchronization and audio signal sample output terminals of said intermediate memory, each having one complete digital The luminance signal sample and the digital
coder means for generating a code word representing a portion of one of the color signal samples and a portion of one of the synchronization and audio signal samples, wherein the first plurality of consecutive code words are one complete a second plurality of consecutive code words representing portions of the color signal samples forming the color signal samples;
for transmitting a television signal comprising a complete sample of said first color signal, a complete sample of said second color signal, and alternating complete samples of said synchronization signal and audio signal; Device. 26. The method of claim 1, wherein the code word comprises a PSK code wave. (27) The method according to claim (26), wherein at least one of the parameters of the PSK code wave, half period length and amplitude, takes two different values. (28) A device for generating a PSK code wave forming a code word in which at least one of the half period length and the amplitude takes two different values, the oscillator generating an output pulse for a predetermined phase angle value. counter means having an input coupled to the output of said oscillator means and a plurality of outputs for producing an output signal at a predetermined count value corresponding to a predetermined phase angle value; a plurality of AND gates having first input terminals coupled to corresponding output terminals and second input terminals; , gate control means having an output terminal for each gate; and an input terminal coupled to the output terminal of the AND gate.
an OR gate having an output terminal; and switching means having a switchover control input coupled to the output terminal of the OR gate. 29. The apparatus of claim 27, further comprising means for controlling the amplitude of each half-wave of the PSK code wave. (30) means for processing a transmitted television signal including a sequence of code words each representing a plurality of components of a composite television signal; a detector for generating a demodulated sequence of code words; and a demodulator. a decoder for receiving the transmitted code word and supplying the plurality of television signal components in parallel to a plurality of output terminals.