Repeater station for information signals containing pseudo-random auxiliary signals

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PATENT AND

Registration Office ^!

SWEDEN

PUBLISHING LETTER No. 351 341 intci H 04 b 3/04

Patent Application. No 2362/69 Arrival 20 II 1969 Validity Day 20 II 1969

Ans. generally available on 24 VIII 1969

Ans. laid out and the pamphlet published 20 XI 1972

Priority requested, from 23 II 1968 (Netherlands, 68 02652)

NV PHILIPS 'GLOEILAMPENP, ABRIEKBN, EINDHOVEN, NEDEBLÄNDEHNA Inventors LE Zegers, ff AM Snijders and J Kuilman, Eindhoven Representative: S Åkesson'

transmission system

The invention relates to a facility comprising a transmitter and a receiver for transmitting information within a prescribed transmission band, wherein the

In total information transmitted cold consists of a main information signal in the form of a synchronous pulse series and an associated auxiliary information signal with less information content, which is formed by a periodic and synchronous pulse pattern located within the frequency band of the main information signal and is not correlated with the main information signal, is equal to the clock frequency of the synchronous pulse series which acts as the main information signal, wherein the pulse pattern originating from the auxiliary information source constructed as a pulse pattern generator is combined with the main information signal in the transmitter in a linear combination device without frequency separation and without time separation, while in the receiver the main information signal and the pulse pattern located within this frequency band are combined with a combined supply line. to which is also supplied the locally obtained pulse pattern derived from the local pulse pattern generator corresponding to the pulse pattern generator in the transmitter, and wherein the output of the modulation device is connected to a smoothing filter, which for automatic phase correction is connected to a frequency determining means in the local pulse pattern wherein an intermediate amplifier is provided in said transmission facility in the transmission path between transmitters and receivers for amplifying the total information to be transmitted and consisting of the main information signal in the form of the synchronous pulse series to be transmitted and the non-correlated pulse pattern serving as a signal. .

Despite a significantly lower level of the auxiliary information signal relative to the main information signal, e.g. -25 dB, the main information signal has a slight influence on the phase stabilization of the local pulse pattern generator and this influence can be further reduced by converting the main information signal in the form of a divalent pulse series into a multivalent pulse series in a code converter, whereby it is possible to advantageously use f code converters comprising a linear combination device, to which the pulses are fed, on the one hand, directly, and on the other, through a shift register with more than two cascade shift register elements, the contents of which are offset by a clock pulse generator connected to the pulse pattern generator. The original divalent pulse series can then be recovered from the multi-value pulse series on the receiver side using the corresponding inverse code inversion devices.

Linear intermediate amplifiers can be used to amplify both the main information signal and the auxiliary information signal during transmission thereof via the transmission path from transmitter to receiver, but thereby introducing a quality influence on the transmission of the main information signal and the auxiliary information signal transmitted at a substantially lower level. which quality influence increases in a disruptive way especially when the signals are transmitted over large distances and thus with a large number of linear intermediate amplifiers.

The present invention is intended to provide a regenerative intermediate amplifier of another construction in a plant of the kind described above, wherein said difficulties are greatly avoided, and which regenerative intermediate amplifiers are distinguished by their particular flexibility in time multiplexing and the passage of channels to additional time multiplexing facilities. the regenerative intermediate amplifiers become very simple, especially at time multiplexes.

The device according to the invention is characterized in that the regenerative intermediate amplifier comprises a pulse generator controlled by locally generated clock pulses for amplification of the pulse series transmitted as the main information signal, and furthermore a shunt circuit coupled between the input and output of the pulse generator terminal of the pulse generator and including the pulse generator said local pulse pattern generator being phase stabilized by a control voltage obtained by modulation in a modulator of the total received information and the periodic pulse pattern generated in the local pulse pattern generator, said pulse pulses for controlling said pulse generator to amplify said pulse generator from said pulse generator. local pulse pattern generator, while the outputs of the pulse regenerator and the local pulse pattern generator by a linear combination device are connected to the transmission path.

The invention is described in more detail below with reference to the examples shown schematically in the accompanying drawing.

Fig. 1 shows a plant according to the invention, while Fig. 2 shows in more detail the regenerative intermediate amplifier with

block diagram.

Fig. 1 shows a single system according to the invention which is designed for transmission within a prescribed frequency band of 0 - 0.75 MHz of a main information signal in the form of divalent synchronous pulses, whose alternate presence and absence characterize the main information signal, and whose appearance moment coincides with a series of pulses at a series having a clock pulse period D corresponding to a frequency of 1.5 MHz, which clock pulse signals e.g. derive from a clock pulse generator 16. Furthermore, the divalent pulses are arranged in successive groups, each consisting of e.g. 31 elements derived from one of 31

In multiplex channels connected to a pulse commutator 61. The 31 time multiplex channels have not been shown further in the figure.

In this system, the pulses emanating from the pulse commutator 61 are fed through a low-pass signal ·· 62 with a cut-off frequency equal to half clock pulse1 in the frequency (ίθ = —gg in 0.75 MHz) and an amplifier 63 to a transfer path in the form of a cable. 64 µ is transmitted to the transmitter, in which is gradually provided a smoothing network 65 for smoothing the amplitude and phase characteristics of the transmission path 64, an amplifier 66, a pulse regenerator 67 for regenerating the received signal pulses in terms of shape and instant of occurrence, and a pulse commutator 68 which distributes the received pulse signals over 31 reception channels not shown in the figure.

In addition to the main information signal, a group synchronization signal is also transmitted in this system for marking the initial moment for each pulse group of 31 elements, in order for the pulse commutator 68 to determine the moment of momentum in each pulse group. Thus, the total information transmitted consists of a main information signal in the form of the divalent pulse series and an auxiliary information signal in the form of a group synchronization signal, the information content of which is considerably smaller than that of the main information signal.

To achieve in the described plant a particularly efficient transfer of information according to patent .344,266. . For example, the auxiliary information signal serving as a group synchronization signal is formed by a periodic and synchronous pulse pattern located within the 0.75 MHz frequency band assigned to the main information signal and is not correlated with the main information signal, which pattern derives from a pulse generator 8 in the sequencer and combined in a pair of sequences. frequency separation with the main information signal.

The pulse pattern generator 8 in the transmitter is constructed as a feedback shift register 10 with a number of shift register elements 11,12,13,14,15, the contents of which are offset by the clock pulse generator 16 connected to the shift register with a constant shift period D, corresponding to the clock pulse frequency of 1.5 MHz.

In a module 2 adder 17 incorporated between the shift register elements 13,14, the output of the shift register 10 being connected on the one hand to the other input of the module 2 adder 17 and on the other hand to the input of the shift register 10. the pulse pattern generator 8 a starting pulse, e.g. originating from a starting pulse source, fed to the input of shift register 10, shift register 10 will start generating a series of pulses, whereby the feedback each having a repetition period T, as explained in the main patent, with the shift register of FIG. 1 has a length of T = (2 ^ -l) D = 31D.

The initial moment of a pulse group in the main information signal is associated with a given state of the shift register 10 in the pulse pattern generator 8, which state, as is known, occurs only once per period T of the pulse pattern generated. For this purpose, in the illustrated embodiment, a group synchronization pulse occurring at this moment on a separate output of the pulse pattern commutator 61 is fed to all the shift register elements 11,12,13, 14,15 through separate inputs to pass the shift register 10 to the state at which simultaneously pulse occurs at the output of all shift register elements 11,12,13,14,15. The pulse pattern occurring at the output of the pulse pattern generator 8 is added at a level e.g. 25 dB below the level of the main information signal in the linear combiner 69 to the main information signal within the prescribed frequency band of 0.75 MHz.

In the cooperating receiver, the main information signal and the pulse pattern located within the 0.75 MHz frequency band are assigned to it and linearly combined with it jointly to a modulation device 19 to which is also supplied the locally obtained pulse pattern derived from a local pulse pattern generator 8 'correspondingly. the pulse pattern generator 8 in the transmitter, the output of the modulation device 19 being connected to a smoothing filter 20, which, for automatic phase correction, is connected to a frequency inhibiting means 21 in the local pulse pattern generator 8 '.

In the receiver shown in Fig. 1, the local pulse pattern generator 8 'is constructed in the same way as the pulse pattern generator 8 in the transmitter, the corresponding elements being provided with the same reference numerals but with an index. Furthermore, the modulation device 19 is constructed as a product modulator, in which one input is connected to the receiver amplifier 66 and the second input to the local pulse pattern generator 8 ', the output being connected to a smoothing filter in the form of an integrating network 20, whose output voltage controls a frequency correction 21 constructed e.g. as a variable reactance connected to an oscillator 16 'serving as a local clock pulse generator. To the product modulator 19, on the one hand, is the received signal consisting of the main information signal and the pulse pattern serving as auxiliary information and on the other hand the local pulse pattern which in shape but not in phase corresponds to the pulse pattern generated on the transmitter side.

As described in detail in the patent specification. 344 266, an input voltage voltage is generated at the output of the integrating network 20 on the basis of the uncorrelated state of the main information signal and the pulse pattern, which voltage in the event of coincidence between the two pulse patterns assumes a maximum value and in the event of two interruptions in time. the pulse patterns less than the shift period D are proportional to these time offsets, but for larger ones, time offsets have a constant minimum value. By supplying said integration voltage as the control voltage to the frequency correction device 21, an accurate phase stabilization of the local pulse generator 16 'is obtained to the phase position of the pulse pattern generated on the transmitter side.

On the receiver side, for generating the local group synchronization signal, the instantaneous moment of a pulse group in the main information signal is derived from a given state of the shift register 10 'in the local pulse pattern generator 8'. For this purpose, in the embodiment shown, the output of each shift register element 11 ', 12', 13 ', 14', 15 'is connected to an individual input of an AND gate 53, which supplies an output pulse only if simultaneously at the output of each shift register element. 11 ', 12', 13 ', 14', 15 'a pulse occurs and feeds this output pulse to pulse commutator 68 as a group synchronization pulse. Due to the phase stabilization of the local clock pulse generator 16 ', the local pulse pattern coincides with the pulse pattern generated on the transmitter side and thus the states of the shift register elements 10 and 10' on the transmitter side and the receiver side are the same at each instant, thereby exceeding the group synchronization pulse oscillation signal. with the group synchronization pulse supplied by the pulse commutator 61 on the transmitter side. The clock pulse from the local clock pulse generator 16 'is applied to the load 68 and is thus used to control the pulse regenerator 67.

In order to reduce the possibility of insufficient or incorrect phase stabilization, it is advantageous to increase the difference between the main information signal and the group synchronization signal, which two signals in the system described so far are formed by divalent pulse series by converting the main information signal into a multivalent pulse series. For this purpose, in the transmitter, the main information signal is fed to a code converter 70 described in Dutch patent application 6702874, which converts a divalent pulse series into a trivalent pulse series. In the illustrated embodiment, the code converter 70 comprises a linear difference generator 72, to which the pulses are fed, on the one hand, directly and on the other, through a shift register 73, the contents of which are offset by the clock pulse generator 16 connected to the shift register 73, while the linear difference generator 72 is preceded by a module 2. adder 71, the second input of which is connected to the output of the shift register 73, and whose output is connected to the input of the linear difference generator 72 so that a very simple inverse code converter in the form of a two-phase rectifier 74 for recovering the original divalent pulse series on the receiver side should be sufficient, as described in the aforementioned patent application. In the embodiment shown, the number of N shift register elements 135,80 ..... 81 in the code converter 70 is equal to the number of shift periods D occurring per period T of the generated pulse pattern, which in the present period of the pulse pattern T = 31 D means a number of shift register elements N = 31 and a total delay time V = ND = 31 D.

As described in more detail in the aforementioned patent application 6702874, the code converter shown reduces the influence of the main information signal on the phase stabilization of the local clock pulse generator 16 'on the receiver side to a considerable extent. In the transformation of the main information signal consisting of divalent pulses into trivalent pulses, single spectral zeros are generated in the

1ε k transmitted frequency spectrum at the frequencies at k = 0,1,2,3, ........ while the auxiliary information signal in the form of the periodic pulse pattern with a period

T = 31 D has a linear spectrum of frequency components at frequencies kk £ = = gij} with k = 0,1,2,3, ...... whereby the frequency components of the auxiliary information signal in the form of the periodic pulse pattern coincide exactly with the separate single zeros in spectrum to the coded master information input.

For the transmission of the transmitted signals from the transmitter to the receiver, an intermediate amplifier 82, which may be constructed as a linear amplifier, is incorporated into the transmission wall 64 for amplifying both the main information signal and the auxiliary information signal with a 25 dB lower level. According to the invention, another method has been followed in the construction of the regenerative amplifier 82, as shown in more detail in Fig. 2.

For amplifying the received signals, the regenerative amplifier 82 of Fig. 2 includes a pulse regenerator 83 which is controlled by clock pulses for amplifying the multivalent pulse series transmitted as the main information signal, the received signals being fed through a equalization network 84 and an amplifier 85 to input pulse regenerator 83. Further, a shunt circuit 86 comprising a local pulse pattern generator 8 'is connected between the input and output of the pulse regenerator 83, said pulse pattern generator being phase stabilized by a control voltage obtained by modulation in a product modulator 19 of the total received information and the periodic current signal and syncron. the local pulse pattern generator 8, wherein the clock pulses for controlling the pulse generator 83 for amplifying the pulse series serving as the main information signal originate from a clock pulse generator 16 incorporated in the local pulse pattern generator 8, the output voltage of the local pulse pattern generator . The level of the local pulse pattern supplied to the combiner 87 is obtained by a set of sets at the aforementioned lower level of -25 dB relative to the main information signal.

In the embodiment shown, the local pulse pattern generator 8 is constructed in exactly the same way as in the transmitter and receiver, the corresponding⁷ The elements have been denoted by the same reference numerals but provided with a double index. In particular, the pulse pattern generator 8 includes a feedback shift register with five shift register elements 11-15, a module 2 adder 17 and the clock pulse generator 16 displacing the contents of the shift register elements 1115, the clock pulse generator 16 being phase stabilized in the same manner as in the receiver of FIG. 1 of the control voltage generated in the product modulator 19, which voltage controls a frequency correction device 21 connected through an integrating network 20 to the clock pulse generator 16. Without being significantly affected by the main information signal, an exact phase stabilization is obtained and as a result synchronization of the pulse pattern generated by the local pulse pattern generator 8 to the pulse pattern generated on the transmitter side, whereby the output signal of the local pulse pattern generator 8 can be directly transmitted to

In addition to the amplification of the main information signal and the auxiliary information signal, which is the only function performed by a linear amplifier, a pulse regeneration is also obtained by the regenerative amplifier of FIG. in the regenerative amplifier, thereby obtaining an optimum quality of transmission from transmitter to receiver. This also makes it possible to achieve an optimal efficiency of the transmission. Attempts have shown that the transmitter, receiver and regenerative amplifier can be connected without difficulty to the transmission wall 64 through adaptation transformers 88, 89, 90, 91. In the embodiment shown, e.g. adaptation transformers that had a straight frequency characteristic in the range of 0.00012 MHz.

Since the group of synchronization pulses can be recovered in a particularly simple manner in the described regenerative amplifier, the advantage of a particularly flexible transmission system is obtained for throughput of time multiplex channels or remote control, especially in the case of time multiplex transmission, in addition to the optimum quality of the transmission and the high transmission efficiency. . The group synchronization pulse is recovered by connecting the ends of the shift register elements 11-15 to an AND gate 63 in the manner already described for the receiver of Figure 1, wherein the group synchronization pulse is derived from the output of the AND gate 53 and used in and for switching of time / multiplexing channels of the regenerative amplifier.

For this purpose, the regenerative amplifier in the 31-channel time multiplex system comprises an N counter 92, which is controlled by the clock pulse generator 16 and has 31 counters and 31 outputs corresponding thereto, each time the N counter 92 is returned to its starting position by the group synchronization pulse. The gate 53. The 31 outputs of the N counter 92 thus output 351341 ⁸ walking pulses corresponding to the positions in question at the calculator.

Further, for the gene coupling of a time multiplex channel, the regenerative amplifier is provided with a selector gate in the form of an AND gate 93 and connected to an output of the counter, with a subsequent memory element 94, for example, a bistable rocker coupling, and a selector gate formed by an AND gate 93 connected to the bistable rocker coupling 94, wherein a connection pulse from a second time multiplex system connected to a further transmission path is fed to both memory element 94 and to AND gate 95 through line 96, which connection pulse e.g. is also obtained from an N counter. A bi-phase rectifier 97 for converting the skin uvine signal formed by a tri-pulse series to the original divalent pulse series is also connected to the output of pulse regenerator 83, the output of two-phase rectifier 97 being connected to the input of AND gate.

For example, if in the described device it is desirable to connect the cold time multiplex channel in the first time multiplex system to the lse time multiplex channel one in the second time multiplex system, for this purpose, the lowest output of the N counter 92 is connected to The AND gate 93 and the lse output of the N counter in the second time multiplex system are connected through line 96 to the memory element 94 and AND gate 95. Thus, the pulses in it. k: th time multiplex channel in the described time multiplex system as. recorded in memory 94 to be read by the lse output of the N counter in the second time multiplex system and transmitted through AND gate 95 to its output, whereby the pulses in the short time multiplex channel, in the first time multiplex system, can be derived from the output of the AND gate 95 exactly at the time intervals assigned to the lse time multiplex channel in the second time multiplex system.

When connecting a plurality of time multiplex channels, AND gate 93, memory element 94 and AND gate 95 are constructed in multiples.

For control of the regenerative amplifier, the memory element 94 and AND gate 95 can often be omitted, and especially for control purposes it is often sufficient to supply the output pulses of AND gate 93 through a separate control circuit to a display device incorporated in the transmitter or receiver.