DE946354C - Receiving arrangement for a multi-channel impulse messaging system - Google Patents

Description

Receiving arrangement for a multichannel impulse messaging system The invention relates to arrangements for converting time-modulated electrical impulses into duration-modulated ones Impulses.

Such arrangements are used for demodulating the received Pulse trains used in impulse messaging systems.

With previously used arrangements for forming time-modulated Impulses in continuous modul. lated impulses became a multivibrator circuit with two stable ones Layers used, which consisted of two tubes that were connected so that the Anode of each tube through a capacitance resistor arrangement to the control grid connected to the other tube. For the selection of the suitable channel impulses In this arrangement, gate pulses are applied to trigger the multivibrator, so that on the next time-modulated pulse it flips into its second position and through the rear edge of the door impulse is tilted back. The multivibrator then becomes a rectangular pulse is obtained, the duration of which depends on the time of occurrence of the channel pulse is determined.

This arrangement has the disadvantage that the output pulse from the multivibrator sometimes persists after the gate pulse has disappeared when the circuit does not is set very precisely.

Furthermore, an arrangement is known in which instead of length-modulated Pulses only one pulse each at the time of occurrence of the leading and trailing edge is transmitted (double pulse modulation). These impulses operate on the receiving side a bistable flip-flop, so that with it the original length-modulated Impulses are restored. It is also known that only one of the two impulses namely to transmit the one with variable phase position (pulse phase modulation), while the fixed pulse edges, which occur at regular intervals representing pulses are added again at the receiving end. To select each Channels are derived from the synchronizing pulses gate pulses with Help special channel distributors in the time periods assigned to the individual channels be moved. For converting the phase-modulated pulses into length-modulated Impulse, a gate tube is provided per channel, which is triggered by the gate impulse for the duration Unlocked about one channel period, the channel pulse to a bistable DC flip-flop lets through, which is thereby tilted. The gate impulse then becomes through D. differentiation the leading or trailing edge derives a toggle pulse for the DC trigger circuit. This results in length-modulated pulses again at this bistable multivibrator, which are converted into the original message content in the usual way.

Such arrangements, which are ground directly with the ones in the sewer distributor Gate pulses work have significant disadvantages in terms of crosstalk between the channels, the sensitivity to noise and the demodulation distortion.

These disadvantages become apparent in a receiving arrangement for a multi-channel messaging system for pulse phase modulation with synchronizing symbol transmission, in which from the synchronizing cells Canal gate impulses are derived, which are cyclically successive in the individual Channels assigned time periods occur, according to the invention thereby eliminated, that a clock pulse series is still derived from the synchronizer characters, whose rectangular single pulses fall in the channel periods and in each channel a normally locked gate tube is assigned to which the entire clock pulse series and the channel gate pulse assigned to the relevant channel is supplied, and which is unlocked when a clock pulse and a gate pulse occur at the same time, so that in the output circuit with the unlocking a pulse begins, that furthermore each Channel is assigned a normally locked dial tube to which the entire received multichannel pulse train is that the resulting pulse at the gate tube as. Voting pulse is fed to the voter tube in such a way that, ß the next to this Tube incoming phase-modulated channel impulse opens the tube briefly, so that a short blocking pulse occurs in the output circuit, which is fed to the gate tube that the pulse in its output circuit is ended and with it at the same time &;: e electoral tube is completely blocked again, and that the now length-modulated pulse from the output of the gate tube of the next demodulation stage fed.

Exemplary embodiments of the invention are shown in the drawings. Fig. I shows: a schematic circuit of an embodiment; Fig. 2 shows one modification of FIG. i with certain advantageous features; Fiig. 3 shows a diagram to explain the operation of the arrangement in Fig. i.

In the circuit of Fig; i is a multichannel pulse train. to the Input terminals i and 2 applied, whereby terminal 2 is connected to earth. These Multi-channel pulse train contains all nested individual channel pulse trains, each sequence being time modulated in accordance with a corresponding signal is. One of these sequences is commonly used for synchronization purposes and then does not carry a message.

The connection terminal i is via a block capacitor 3 with the control grid a channel selector tube q. connected, which is controlled by a gate tube 5 so that it responds only to the impulses of the particular channel to be selected. the Gate tube 5 itself is through a series of gate pulses. controlled the same Have repetition frequency as the synchronizer pulses and that of a suitable one Tap point on a delay network (not shown) which the synchronous pulse; e (or locally generated pulses generated by the Synchronization pulse, e synchronized sin) can be applied. These gate impulses are applied with positive polarity to the connection terminal 6 and then via a blocking capacitor 7 and a resistor 8 .au, the control grid of the gate tube 5. When the gate impulse considerably from; deviate from the desired rectangular shape, especially the Case is, if they are derived from a delay network, it becomes a sequence of locally generated, precisely rectangular clock pulses with positive polarity .an the terminal 9 is applied, which via a block capacitor io and the diode i i with- connected to the control grid of the tube 5. Is. If N dile is the total number of channels Including the sync channel, then. should be the repetition frequency of the clock pulses NF / 2, where F is the repetition frequency of the 'synchronization pulses is. The duration of each clock pulse should be i / NF.

In fact, two separate sequences of clock pulses are required, which i 8o 'are out of phase. A sequence becomes for di, e even channels and the other sequence is used for the odd numbered channels. The use of two such sequences of clock pulses is known.

The anode of the diode z i is connected to the control grid of the tube 5 and its The cathode is connected to earth via a resistor 12. The connection point of the Elements 7 and 8 are connected to earth via a resistor 13. As later in more detail is explained; the tube is biased so much beyond the limit point that it does not respond to the channel pulses if it does not receive a voter pulse from the Gate tube 5 receives and the gate tube 5 generates the voting pulse only when a clock pulse coincides with a gate pulse. the Tube q. speaks to the next Channel pulse on after it has been opened and generates a short negative Pulse which is applied to the gate tube 5 and blocks the same, so that the Torröhre generates a rectangular output pulse, the front edge of which with the front edge of the corresponding clock pulse coincident: @ert and its rear Edge coincides with the channel pulse. These output pulses are via a Block capacitor 1 ¢ applied to a low-pass filter 15 of a suitable type, which serves as a demodulator. The output pulses are in accordance with the time phase modulation of the original channel pulses are time-duration-modulated and can be used in the usual way demodulated by the filter. Have the continuously modulated output impulses in contrast to the usual pulse demodulators, solid front edges.

The terminals for the supply voltage source (not shown) for tubes q and 5 are 16 and 17, with 17 being grounded. The anode of the tube 5 is connected to terminal 16 via two resistors 18 and i g, the connection point of which is connected to the block capacitor 1 ¢. The cathode of this tube is through a Bias voltage resistance 2o, which is bridged by a capacitor 2i, with Earth connected. The safety gate is also connected to earth via a resistor 22. The dashed line, capacitor 23 represents the capacitance of the safety gate and the connection lines to earth. The anode of the tube q. is with the connection 16 through a resistor 2 ¢ connected and the cathode is through the connection with the connection point of the resistors 25 and 26, which are im. Series between the terminals 16 and 17 lie, positively biased. The catching grid of this tube is directly with Cathode connected and the control grid is connected to ground via resistor 27 '.

The screen grids of the tubes and 5 are connected to the connection 16 via the resistors 28 and 29 and to earth via the capacitors 30 and 31.

The anode of the tube q. is with the grille of the tube 5 over a Block capacitor 32 and connected via a diode 33, the anode of which is on the catching grid lies. The anode of the tube 5 is connected to the cathode of the via a blocking capacitor 34 Tube q. switched.

The mode of operation of the circuit is explained with reference to FIG. The cathode bias of the tube 5 should be so great that this tube only opens is when a gate pulse applied to terminal 6 at the same time as a the terminal g applied clock pulse occurs. The bucket of gate impulses is at a in Fig. 3 shown. D '-, es: he impulse is given in its time of appearance by a delay: network synchronized in such a way that it selects a pulse of the to be demodulated Channel. The gate pulse becomes ordinary when passing through the network : somewhat distorted, like this in Ff ,. 3, a is shown. The rectangular clock pulses are shown at b (Fig. 3). The leading edge of each of the pulses increases: the potential of the grid of the tube 5 almost to the limit point without however opening the tube. As a result, the gate pulse can sufficiently exceed the grid potential at time 35 (FIG. 3) increase the cut-off point, and if the lattice time constant of the tube is short, will at the anode of the tube the leading edge of a practically rectangular negative Output pulse generated as shown at 36 in curve c (Fig. 3).

The tube [should] be pretensioned so that it does not respond to the channel impulses (shown at @d, Fig. 3) which are applied to the connection terminal: ei. The negative pulse taken from the anode of the tube 5 is passed through the blocking capacitor 34 to the cathode of the tube q. applied and reduces the bias so that the tube responds to the next channel pulse (Fig.3, d). This increases the anode potential of the tube q. suddenly decreased, and a very short, negative differentiated pulse is applied via the block capacitor 32 and the diode 33 to the arresting grid of the tube 5 and terminates the negative pulse (c, Fig. 3) at time 38, which with: the Channel pulse 37 coincides. The amount of the anode potential of the tube 5 is transferred to the tube at this time and limits this tube so that both tubes are again in their original state. The output pulse shown at c (FIG. 3) is applied to the filter 15 and its duration depends on the time of occurrence of the corresponding channel pulse 37. In this way the output pulse has a fixed leading edge and a variable trailing edge. Attention is drawn to the fact that in the absence of any channel pulse, the output pulse c is terminated at time 39 , since it is terminated by the trailing edge of the corresponding clock pulse, so that, if the channel pulses should be suppressed, a sequence of output pulses of constant width is applied to the demodulation filter 15.

The parts of the gate pulse (Fig. 3, a) between times ¢ o and 35 and between .the times 39 and ¢ 1 have no effect on the tube 5, since the corresponding Clock pulse is not available at these times and therefore the tube does not respond can. If the gate pulse applied to the tube has a sufficient amplitude, a very sharp leading edge 36 is obtained for the output pulse, and if so the tube ¢ has a short lattice time constant and the channel pulses applied to it have a sufficient amplitude, will also have a very sharp posterior cartilage 38: generated.

The diode 33 serves the purpose of the tube 5 during the period between the trailing edge 38 of the output pulse and the trailing edge of the clock pulse keep in the impermeable state. The applied to the safety gate via the diode 33 short differential pulse loads the dashed line capacitance 23 of the safety gate negative on, and when the differential pulse disappears will the diode is blocked, and the capacitance 23 can then only move slowly over the high-impedance Discharge resistor 22. This keeps the safety gate negative, which means that the Tube 5 is kept locked. There could be a small one between the safety gate and the earth Capacitor can be switched if the safety grid capacitance is not large enough is, but this is usually not necessary. The time constant of circuit 22, 23 should be short enough so that the safety gate can assume the potential o before. the next pulse of the same channel arrives.

It will be clear that none of the other channel pulses past 37 have any Can exert an effect on the circuit, since both tubes are blocked, except during the period when the gate pulse coincides with the clock pulse. The order thus practically prevents any crosstalk between the various channels.

By a slight modification of Fig. I could ai the diode i i and the resistor 12 can be omitted. The capacitor i o could in this case be connected to the screen grid of the tube 5 and the bypass capacitor 31 could be replaced by a suitable resistor. Be that way the gate pulses and the clock pulses are applied to separate grids of the tube 5. There .the screen grid carries a noticeable current is the disadvantage of this arrangement, that the clock pulses must be applied with greater power.

Fvg. 2 shows .three minor modifications of FIG remains practically the same. Same. Elements in the two figures are the same Reference numbers given.

The three amendments are as follows: a) This amendment concerns the coupling arrangement between the anode of the tube 5 and the tube q. and results better results than the corresponding arrangement in Fig. i. The anode of the tube 5 is connected to the control grid of the tube ¢ badly a transformer ¢ q. coupled, the secondary winding of which is terminated by a resistor 45. This transformer should be switched in such a way that a positive pulse is sent to the control grid when the tube 5 is permeable. In this case @es is also preferable the cathode bias resistor 26 through a bypass capacitor 46 Shunt in order to avoid negative feedback, which is otherwise caused by this resistance would be introduced.

In this case, elements 3 and 27 are connected to the safety gate, so that the channel impulses from connection i to the interception grid instead of the control grid, like in. Fig. I. In this case, the catch grid is from the cathode separated.

Attention is drawn to the fact that by applying the voter impulses to the control grid of the tube q. the tube for the whole period between adjacent ones Voter pulses is completely blocked, so that the incoming during this period Channel impulses cannot generate a screen grid or fatng grid current, which means crosstalk between the channels is prevented.

The application of the voter pulses and the channel pulses to the voter tube ¢ in the manner described is therefore preferable.

The other changes shown in Fig. 2 are minor Importance and are as follows: b) The diode 33 is connected to the control grid of the tube 5 connected instead of the safety gate. The usual grid leakage resistance is 42, and the dashed capacitor 43 represents the control grid capacitance which works in the same way as the safety grid capacitance 23 of FIG. i. This makes it is possible because: ß the clock and gate pulses. to the catching grid of the tube 5 instead can be applied to the control grid by connecting the connection point of elements 8 and I I with the safety gate.

c) The output pulses are taken from the cathode of the tube 5, by .the blocking capacitor 14 with the cathode instead of with the connection point of resistors 18 and 19 is connected. In this case, the bypass capacitor soot 21 can be omitted.

These three amendments are all independent of one another, and any one of them could also be applied to Fig. i.

Instead of the diodes i i and 33, other diodes can of course also be used Rectifiers are used as well as generating the bias voltages on others than can be done in the manner illustrated.

The advantages of the arrangements according to the invention are briefly as follows: i. The . Tube 5 generates a rectangular voter pulse with very steep edges, thereby increasing the time available for the channels. So it can: either the modulation depth or the number of channels can be increased.

2. The channel impulses block both tubes at the same time, whereby the Possibility of one. Cross-talk between adjacent channels is avoided.

3. The circuit does not constitute an oscillator, and therefore it exists no tendency for the circuit to be operated accidentally or out of period of the selected channel pulse continues to oscillate.

¢. In the case of: previously proposed pulse selection arrangements, the Output pulses taken from the screen grid of a tube and have accordingly a low energy. By decreasing the pulses from the anode or cathode becomes one received greater energy.

5. In known arrangements it was necessary to have a separate tube to be provided for the formation of the output and output pulses. In the present invention the shaping is carried out in a more satisfactory manner through the gate tube, thereby reducing the number of tubes used.

Claims (7)

PATENT CLAIMS: i. Receiving arrangement for a multichannel nacUri.chten system for pulse phase modulation with Synchronization character transmission, at which are derived from the synchronizing signals channel gate impulses, which are cyclic occur consecutively in the time periods assigned to the individual channels, characterized in that a clock pulse series continues from the synchronization characters is derived, the rectangular individual pulses of which fall within the channel periods, and that each channel a normally blocked gate tube (5) is assigned to the entire clock pulse series and the channel gate pulse assigned to the relevant channel. are supplied and the simultaneous occurrence of a clock pulse and a gate pulse is unlocked so that im. Output circuit with the initial blocking a pulse begins, that a normally-locked dial tube (q.) is also assigned to each channel is to which the entire received multichannel pulse train lies, that of the gate tube resulting pulse is fed as a voter pulse to the voter tube that the The next phase-modulated channel pulse arriving at this tube briefly triggers the tube opens, so that a short blocking pulse occurs in the output circuit, that of the gate tube is supplied in such a way that the pulse existing in its output circuit is terminated and at the same time the voting tube is completely blocked again, and that the now length-modulated pulse from the output of the gate tube of the next demodulation stage is fed. 2. Receiving arrangement according to claim i, characterized in that the clock pulses and the gate pulses are applied to the same electrode of the gate tube. 3. E.inpfamgsordnung according to claim 2, characterized in that the clock pulses via a rectifier to said electrode of the gate tube. ¢. Receiving arrangement according to Claim z and / or 3, characterized in that the Gate and clock pulses are applied to the control grid of the gate tube. 5. Reception arrangement according to claim 2 and / or 3, characterized in that the gate and clock pulses are placed on the safety gate of the gate tube. 6. Receiving arrangement according to claim i, characterized in that the blocking pulse from the voter tube via a rectifier is applied to the gate tube. 7. receiving arrangement according to claim i, characterized in that that the voting pulse from the anode of the gate tube via a block capacitor to the Cathode of the voter tube is applied and that the channel pulses to the control grid the voter tube. B. receiving arrangement according to claim i, characterized in that that the voting pulse from the anode of the gate tube via a transformer to the Control grid of the selector tube is applied and that the channel pulses to the safety grid the voter tube. Publications considered: Swiss Patent No. 23q: 677.