DE2357703A1 - PROCEDURE ZR8 PHASING OF REFERENCE CARRIERS FOR A DATA TRANSFER SYSTEM WITH FREQUENCY DIFFERENTIAL PHASE MODULATION - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT Munich, 19 NOU19 7 3 Berlin and Munich Wittelsbaeherplatz 2

73-2145

Method for phasing reference carriers for a data transmission system with frequency- differential phase modulation. ^ - __

The invention relates to a method for phasing reference carriers for a data transmission system with frequency-differential phase modulation, according to which several carriers lying in phase with one another are phase-modulated in consecutive modulation sections and transmitted together. In this case, the receiving end recovered from the transmitted phase-modulated carriers by demodulation with the reference beams, the transmitted data, wherein the carriers and the Referenzträgem is the transmitting end or the receiving end each associated with a fundamental oscillation of the same fundamental frequency and the repetition rates of the. Carriers or reference carriers are multiples of the basic frequency. In addition, a first number of basic periods is assigned to a second number of modulation sections on the transmission side during an excess period.

In the above-mentioned methods for frequency-differential phase modulation, the transmission side and the reception side are used The same parts of the modulation sections are assigned to the basic periods occurring. The invention is based on the object to specify a method that enables this assignment with little technical effort.

According to the invention, a reference signal is generated on the transmission side, marks the beginning of the overtime. With this reference

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signal, one of the carriers is modulated, so that the modulated carrier in addition to the data to be transmitted and in addition for information on the start of the modulation sections also 'the information on the start of the excess period contains. The modulated carrier is transmitted and on the receiving side it is used to set the phase position, the reference carrier set.

The method according to the invention is characterized in that it can be implemented with little technical effort, because the information regarding the start of the overperiod is not with an additional carrier but with one of the carriers which are intended for data transmission.

It is advisable to use an R-square-shaped reference signal as the reference signal To generate a signal whose pulse edges coincide with the beginning of the modulation sections occurring on the receiving side and whose square-wave pulses have two pulse widths, a first pulse width of which has the duration of Modulation sections and a second pulse width marks the beginning of the superperiods.

In a preferred embodiment of the invention, the first pulse widths of the reference signal are spaced apart of two modulation sections each, whereas the second pulse widths are spaced apart by three modulation sections each to have.

In the following, exemplary embodiments of the invention are described with reference to FIGS. 1 to 6, with several figures The same objects shown are marked with the same reference numerals. Show it:

Fig. 1 shows a system for the transmission of data with frequency differential Phase modulation,

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2 and 3 representations of signals which occur in the system according to FIG. 1, ■ -.-

FIG. 4 shows a more detailed representation of the diagram in FIG. 1 synchronizing device shown,

Fig. 5 timing diagrams of signals generated during the operation of the Synchronizing devices shown in Fig. 4 occur and

FIG. 6 shows a more detailed illustration of the evaluation circuit shown schematically in FIG.

1 shows a data transmission system for transmission of data using frequency differential phase modulation. The data source DQ gives the data in the form of a binary signal which assumes two different amplitude values, the binary values of which are identified by the reference symbols O and 1. The serial-parallel converter SP receives the data serially and forwards them in parallel to the encoder KD. To the encoder KD the modulators ICD1, MD2, MD3, MD4 are connected, each of which has a carrier F1 or F2 or F3 or \ tf. F4 from the generator GEN is supplied. For the sake of simplicity, only four modulators MD1 to MD ^ are shown, whereas in practice generally a significantly larger number of modulators and appropriate carriers is used.

The phase modulated carriers F10, F2O, F30, F4O are from delivered to the outputs of the modulators MD1, MD2, MD3, MD4 and fed together to the transmitter SE and via a transmission s route - for example via a shortwave route to the Transmit recipient EM.

In the receiver EM, the transmitted composite signal is amplified and the amplified composite signal G is the output Inputs of the demodulators DM1, DM2, DM3, DM4 and the synchronization device SYN supplied. The synchronizing device SYN also supplies the reference carriers R1, R2, R3, R4

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.If.

whose help the individual phase-modulated signals are demodulated. At the outputs of the demodulator are en the decoders he DK1, DK2, DK3 connected, which the Undo coding made using the encoder IiD. With the parallel-serial converter PS the parallel incoming data are output serially to the data sink DS. As a data sink, for example a teleprinter or a data display device can be provided.

Fig. 2 shows schematically the carriers F1 to F4, which are multiples of the fundamental frequency of the fundamental oscillation Fs. the Fundamental oscillation Fs and the carriers F1 to F4 are phase-locked to one another. The zero crossings of the fundamental oscillation Fs

lie at times t11, t20, t3O, ti43, 't152, ti6i.

At these times, all zero crossings coincide simultaneously the carrier FI to F4. In one embodiment, the fundamental oscillation Fs has a pulse repetition frequency of 80 Hz. The period ρ of the fundamental oscillation Fs is therefore equal to 1/80 sea in this case for example.

Phase changes occur in the course of the phase modulation in temporally successive modulation sections m. The modulation section lasting from time t11 to time t21 m1 is somewhat larger than the basic period p1, which lasts from time t11 to time t20. In this embodiment, the modalation sections follow m1, m2 ... mi4, m15 with a repetition frequency of 75 Hz, so that each modulation section m has a duration of 1/75 sea. Has. Beginning and end of the modulation sections m generally do not coincide with the zero crossings of the fundamental oscillation Fs. Coincide at times ti 1 and ti6i however, beginnings of the modulation sections m with zero crossings of the fundamental oscillation Fs Time t11 begins and ends at time ti6i

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thus 16 basic periods pi, p2 ... p15, pi6 and 15 modulation sections m1, m2 ... mi4, m15. For the sake of simplicity of illustration only the first two and the last two basic periods and modulation sections are shown. the Repetition frequency of the overperiod is 5 Hz.

The carriers P1 to F4 occurring on the transmit side correspond on the receiving side, the reference carriers R1 to R4, their repetition frequencies Multiples of the fundamental oscillation on the receiving side -.Fe are. The reference carriers R1 to R4 occurring on the receiving side and the fundamental frequency Fe on the receiving side are also phase-locked connected to each other. All of them coincide with the zero crossings of the receiving fundamental frequency Fe Zero crossings of the reference carriers R1 to R4.

In the modulation system with frequency-differential phase modulation phase differences of two adjacent carriers are assigned to the data to be transmitted. For example such data can be transmitted by phase differences of the carriers F2 and F3. Since the carriers F1 until F4 have a different period, these phase differences change continuously from the modulation section to modulation section. It is true that the phase differences after successive basic periods ρ are the same ¥ ert, not successive modulation sections m. For example, the carriers F1 and F2 have a phase difference of 0 at time t11, whereas they have after the modulation section m1 have a phase difference of 90 ° at time t21. If on the transmission side the basic periods p1 to pi6 are parts of the modulation sections m1 to m15 are assigned, then the Phase positions of the reference carriers R1 to R4 are set on the receiving side in such a way that the basic periods on the receiving side p1 to pi6 again the same parts of the modulation sections m1 to m15 are assigned.

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To phase the reference carriers R1 to R4, a reference signal E is generated in the generator GEN according to FIG. - which contains the information as to when the superperiod q begins on the transmission side. The reference signal E is used in the modulator MD4 modulates the carrier F4 and the modulated carrier F4O is delivered to the transmitter SE and to the receiver Transfer EM. On the receiving side, modulation is carried out with the help of de.s Carrier F40 set the phase position of the reference carriers R1 to R4.

The reference signal E shown in FIG. 3 is shown on a different time scale compared to FIG. From the point in time ti 1 to the point in time t311 there is a full one Period of the reference signal E shown, which is equal to the sum of the two superperiods q and q2. The period from time t11 to time t311 thus includes at present embodiment 30 modulation sections. The reference signal E ordered from square-wave pulses, of which the pulses E3, E4, E5, E6, E7, "ES each have the duration of two modulation sections, whereas the pulses E2 and E9 each have the duration of three modulation sections.

FIG. 4 shows in more detail an exemplary embodiment of the synchronizing device SYN illustrated in FIG. 1. These The synchronization device consists of the oscillator OS, the frequency changing stage FS, the frequency dividers FT1, FT2, from the evaluation circuit BW, the modulators MD5, MD6, also from the correlators KR1, KR2, KR3, KR4, from the phase shifters PS1, PS2, from the signal converter stage SU, the GSYN coarse synchronization stage and the analog-to-digital converter AD. ·

The oscillator OS generates a clock signal with a relatively high pulse repetition frequency generated and the frequency change stage FS

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fed, which causes either a fade-in or a fade-out of individual pulses.

The frequency divider FT1 outputs the signal shown in FIG 'C and the reference carriers R1, R2, R3, R4. The frequency divider FT2 generates the signals A1, A2, A3, A4 shown in FIG. 3. ■

With the signal A1 using the modulator MD5 causes an amplitude modulation, with a phase of 0 ° of the reference carrier during the duration of the 1 values of the signal A1 R4 is set, whereas no signal is emitted during the duration of the 0 values of the signal A1. With the Modulator MD6 causes a phase modulation in such a way that the reference carrier is used for the duration of the 1 values of the signal A2 R4 with phase 0 and during the duration of the 0 values of the reference carrier R4 with a phase of 180. In addition, each of these modulated signals is gated with the signal A3 acting as an integration clock, as a result of which the signal K or H shown in FIG. 4 results.

In FIG. 5, the diagram F41 is shown at the top, which shows the phase position of the signal F40 drawn in FIG. 1. The two binary values of diagram ¹ FA1 thus correspond to the phases of 0 ° and 180 ° of signal F40. The diagram K shows the amplitude of the reference carrier R4 to be modulated, the reference symbol 1 or 0 being assigned a specific amplitude with the phase '0 or no signal. Diagram H shows the phase position of the reference carrier R4 to be modulated, whereby the reference symbol 1 or 0 or -1 is assigned a phase e of 0 ° or no signal or a signal with a phase of 180 ° = *

Two different types of correlators are provided for generating the signals L, M ₅ N _{5 P.} The correlators KR1

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and KR2 form the correlation functions between the signal according to diagram F41 and the signal according to diagram H. The correlators KR3 and KR4 form the correlation functions between the signal according to diagram F41 and the signal according to diagram K. The signal according to diagram F41 is contained in the composite signal G. So that the correlators deliver a usable signal even with any phase position of the signal in accordance with diagram F41, the two phase shifters PS1 and PS2 are provided, each causing a phase shift of 90 °. It can be seen from the signals N and L that each correlator KRI _1, KR2, KR3, KR.4 always integrates over two times ti and thus over two modulation sections m. The signals L, M, N, P are a measure of the time shift between the signal according to diagram F41 and the signals according to diagrams K and H.

In Fig. 5 three cases are shown, which relate to correct synchronized reference carrier, on leading reference carrier and refer to the dead time range. The signals N, L, P, M can have DC voltages between the amounts + 2V and -2Y assume. In particular, the amounts are OV, -1V, -2V drawn. In the first case, the diagram part K1 falls precisely in time within a modulation grid m. This case is characterized by the signal N, which assumes a voltage of OV at point N1. The dead time signal Q assumes the binary value 0. In the second case, the diagram part K2 is ahead with respect to the modulation grid M. In this case, the signals N and L at points N2 and L2, respectively, have the same polarity. If the signal part K2 is lagging, these two points N2 and L2 would have opposite polarity. The dead time signal Q increases the binary value 0. In the third case, the time base of the receiver is a modulation section m compared to the Signal part K3 offset. This case is characterized by

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net that the signal L at point L3 assumes a voltage of 0V. In this case, the dead time signal Q has the binary value 1.

The signals N, L, P, M serve as a criterion for the rough phase correspondence between the sending and receiving sides occurring modulation sections. This phase correspondence is used in the present transmission method referred to as coarse synchronization. This coarse synchronization is carried out with the coarse synchronization GSYN shown in FIG. 4 in a manner known per se. The coarse synchronization stage GSYN is on the one hand connected to the frequency change stage FS and operates there the fade-in or fade-out of individual impulses. On the other hand, the coarse synchronization stage outputs the signal S which always assumes the binary value 1 when-the coarse synchronization is finished.

The signals N, L, P, M also serve to phase in the excess period, so both on the transmit side and on the receive side The same parts of the modulation sections are assigned to the basic periods. This phasing is carried out with the Evaluation circuit BW shown schematically in FIG. 4 carried out, to which the signals A4, Q, .S are fed. That Signal W only assumes a 1 value if the level of the The composite signal G shown in FIG. 1 is in the target range.

The analog / digital converter shown in FIG. 4 receives the analog signals N, L, P, M and emits the binary signals W4, IA, P4 and M4 via its outputs. The analog values below a specified threshold value are assigned the binary value 0 and above the specified threshold value the binary value 1. For example , the signal N is assigned the binary value 0 of the signal N4 until the point N3 is reached, and from the point N3 of the signal N, the signal N4 takes on

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the binary value 1. As can be seen from Fig. 5, it is another polarity reversal made. :

The signal converter stage SU shown in FIG. 4 ″ initially receives the signals N4, ΙΑ, P4, M4 and generates the dead time signal Q. The mode of operation of this signal converter stage SU can be seen in the table below.

N4 L4 · P4 M4 Q

1 0 1

1 0 0 0 0 1 0 0 0 O 1 0 Tabel

The dead time range is thus signaled with the signal Q = 1. A dead time range occurs when either N4 = 1, IA = O, P4 = 0, M4 = 0 or N4 = 0, L4 = 0, P4 = 1, M4 = 0. With the Signal Q = O indicates that no dead time range occurs.

Fig. 6 shows the evaluation circuit BW in more detail. It consists of the NAND gates NA1, NA2, NA3, the inverter IN, from the NOR gates N01, N02 and from the bistable flip-flops ST1, ST2, ST3.

A 0 signal is only issued from the output of gate NA1 if if a dead time range is signaled with Q = 1, if the finished coarse synchronization is signaled with S = 1 becomes and if with ¥ = 1 a nominal level of the signal mixture G is signaled. The stages ST1 and ST2 form a first counter and the stage ST3 forms a second counter. As soon the first counter with levels ST-1 and ST2 to 3 has counted,

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the signal D appears at the output, which means that in the frequency change stage FS shown in Fig. 4 a Insertion of pulses is made. A phase shift is thus carried out by a modulation section. Simultaneously with the output of the signal D, the first counter is blocked via the inverter IN and via the gate NO1, so that with the signal S = 1 only a single phase shift is carried out by one modulation section will. The stage ST3 is supplied with the signal A4 shown in FIG. 3, which has a pulse repetition frequency of 2.5 Hz Has. The two stages ST1 and ST2 are reset via the output of the gate NA3, if within a period from 2.5-Hz no signal S = 1 occurs, which signals the completed phase-in.

During the phase-in of the reference carriers R1, R2, R3, R4 generated on the receiving side, the procedure is known per se first carried out the coarse synchronization. In the course of this Modulation sections on the transmit side are coarse synchronization and the reception-side modulation sections are brought into congruence. In general, this does not become instantaneous achieves that the first basic period and the first modulation section begin simultaneously. In this case, the dead time signal Q = 1 generated because those described with reference to FIG Dead time ranges occur. Using the signal D, the time base of the receiver is changed in phase by one modulation section postponed. This process is continued until no more dead time ranges are signaled with Q = O will. This ends both the coarse synchronization and the phasing of the reference carriers R1, R2, R3, R4.

The signal converter stage SU shown in FIG. 4 can be formed, for example, from the equivalent gate GTI. And from the two AND gates GT2, GT3.
4 claims
6 figures

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Claims (4)

- 12 claims j method for phasing reference carriers for a data transmission system with frequency-d ± fferential phase modulation, after which several carriers which are phase-locked to one another are phase-modulated and transmitted jointly in successive modulation sections, and whereupon the transmitted data is recovered from the transmitted phase-modulated carriers by demodulation with the reference carriers on the receiving side / ground, the carriers or the reference carriers being assigned a fundamental frequency of the same fundamental frequency on the transmit side or the receiving side, and the repetition frequencies of the carriers or the reference carriers being multiples of the base frequency, and on the transmit side a first number of base periods of a second number of modulation sections during an overperiod is assigned, characterized in that a reference signal (E) is generated on the transmission side, which indicates the beginning of the excess period (q) that with the reference signal (E) one the carrier (F4) is modulated so that the modulated carrier (40) contains not only the data to be transmitted and in addition to the information regarding the start of the modulation sections but also the information regarding the start of the excess period (q) that the modulated carrier (40) is transmitting and that the phase position of the reference carriers (R1 to R4) is set on the receiving side with the aid of the modulated carrier (F40). 2. The method according to claim 1, characterized in that that a rectangular signal is generated as the reference signal (E), the pulse edges of which with the The beginning of modulation sections occurring on the receiving side coincide and its square-wave pulses have two different pulse widths have, of which a first pulse width the duration of the modulation sections and a second pulse width marks the beginning of the overperiod (q). VPA 9/240/2094 - 13 - 503822 / 043-2 3. The method according to claim 2, characterized in that g e k e η η - ζ eich η et that the first pulse widths are separated by two modulation sections (m) each and that the second pulse widths of the reference signal (E) are separated by three modulation sections (m). 4. The method according to claim 1, characterized in that that in the course of a coarse synchronization, the transmitted modulation sections on the transmission side with the modulation sections occurring on the receiving side be brought in phase in agreement that a dead time signal (Q = 1) derived with the help of the reference signal (E) that the dead time position of the reference signal (E) with respect to the phase position of two occurring on the receiving side Characterizes basic periods and that by means of the dead ■ time signal (Q) the phase positions of the reference carriers generated on the receiving side be shifted by one modulation section (m) each until no more dead time signal (Q = O) is generated will. VPA 9/240/2094 - SÜ9822 / Q432