DE1911691A1 - Circuit arrangement for the direct display of the mean value from several successively arriving measured values - Google Patents

Description

Circuit arrangement for the direct display of the mean value from several measured values arriving one after the other.

The invention relates to a circuit arrangement for direct Display of the mean value from several successively arriving measured values.

For the acquisition of strongly scattering measurement values, e.g. in exploration physical phenomena, is often the e calculation of the mean value from the Results of many individual measurements required Implementation and evaluation extensive statistical series of measurements with a large number of individual measured values could be significant Lich can be accelerated when the (arithmetic) mean values by the measuring device themselves would be formed and reported.

In order to accomplish this task with known means, one would have to all values of a series of measurements are saved and after the series is terminated in a computer, analog or digital, the mean value can be calculated. This Because of the need to store all individual measured values at the same time, this would be a long way off expensive, especially if many values, e.g. more than 10, are used for the mean value should be. The mean value of each series of measurements would then be displayed shortly after whose end eræ follow.

The invention relates to a circuit arrangement for direct display the mean value of several successively arriving measured values, those of the simultaneous There is no need to save all values and also during the course of the Series of measurements at each moment the respective mean value from the values that have already arrived Values.

For this purpose, according to the invention, every time a new measured value arrives, the stored, from the measured values that have already arrived, in the same way The mean value formed by the number of values that have already arrived finally of the new, divided difference between the new value and the previous mean value added.

This also results in the lower cost of the advantages, that during the whole series of measurements from the beginning the resulting measured value (Mean) track and also at will. a series of measurements prematurely can stop when it is determined that the mean value changes with each further measurement changes only marginally.

We denote with w1, w2 »w3, .... . . wn the measured individual values and with M1, M2, M3 ............ Mn the mean values formed from the measured values up to and including the same index number, where w1 is also M1 at the same time (the first measured value is also his own mean value), then after n measured values the mean value is: or Each new measured value that arrives provides a new summand in the series and thus corrects the mean value that has appeared before it by its corresponding portion.

For this purpose a division of the differences by the number of received Measured values must take place, the arrangement requires a counter that comes with each Value increments by one digit and the partial ratio in each case according to its status adjusts. (If a value is completely out of the way, it can only be sorted out if one cancels it circuit-wise -However, the given arrangement is for such Cases that are mostly based on operating errors are not responsible, especially the Messenda Yes, immediately notice any drift in the mean value and then take action can). A mechanical or electronic counter can be used for this purpose. Its counting capacity is decisive for the maximum number of measured values for a series of measurements can belong with a mean; In addition, a new series of measurements must then be with a new mean value.

The effort for this counter is not great; one uses e.g.

electronic counting decades, you can already do so with just two decades Record 100 values - sufficient for most cases.

The storage of the mean value, formation of the difference from incoming = incoming Value and stored mean value, division of the difference value, addition of the divided The difference to the existing mean value can be digital or analog. The digital Y processing Errordert the greater effort, but offers da = also for greater accuracy.

Zin simple embodiment in analog technology is in ig.1 shown, on the basis of which the mode of operation is explained in more detail: In Fig.1 are 1,3 and 4 operational amplifiers; 2 is a Schmitt = trigger that is at its output Voltage (L signal) emits as soon as a measured value appears at its input, and which, due to its tilting behavior, has a defined edge steepness of the appearing and supplies vanishing output voltage, so that it is the counting input of the can control electronic counter 7 consisting of two decades; 8 is a Group of 8 resistors connected in parallel, each of which has a field effect = transistor in the line can be switched on and off, where = with the field effect transistors can be controlled by the 8 outputs of the two counting decades so that the resulting The value of the resistors connected in parallel corresponds to the respective counter reading Divider ratio corresponds to; for this purpose, the 1-2-4-8 code for the counting decades can be used be used. 18 is a logic circuit that depends on the appearing and vanishing measured values at the input of the arrangement two relays 12 and 13 and two transistors, 14 and 16, in a certain time sequence shown in the diagram Fig.2 drives. The black bars denote the time periods in which the Kontak = te 12, 13 closed or the transistors 16, 14 are conductive. For the sake of completeness, FIG. 3 shows a simple example of a suitable one Circuit specified, which is described below.

The mode of operation, Fig.1, is as follows: The measured values are taken from the The respective (e.g. physical) measuring arrangement in the form of a (in the example shown positive) voltage is supplied to point 25, from where it is applied to the input of the amplifier 1 as well as the trigger 2.

The first actual value hits (w1 in Eqs. (1) and (2)) at the input of the amplifier 1 on: The value also supplied to this amplifier - Mn-1 (see equation (2)), namely the mean value from the respective previous measured values is still zero because yes before no measured values were available yet.

The amplifier 1 also supplies the first at its output Measured value. This reaches the input of the amplifier via the resistor FZT group 8 3. The resistance FET group is switched through by the counting decades 7 that are set to "1", that the resulting resistance is equal to the negative feedback resistance 5 of the amplifier 3 is. Here, too, the amplifier input via the switch that is still closed 13 (see diagram Fig. 2) also supplied value Min 1 is still zero, also appears at the output of amplifier 3 the first MEB value. It is stored in the capacitor 10, since the amplifier together with the diode 23 and the FET 24 equals a linear peak value = judge is switched.

According to the switch diagram Fig. 2, the relay 12 now closes its contact (The switching operations also taking place at 13, 14 and 16 are at the first measured value still irrelevant), whereby the measured value is sent to the - also as a linear peak value rectifier switched - amplifier 4 arrives, which stores it in capacitor 11 and on Instrument 9 displays. It is present here as a negative voltage, if it was originally a positive voltage at the input of amplifier 1, since everyone Operational amplifier reverses polarity and the measured value passes through three amplifiers Has. The first measured value now appears, with a negative sign, also as an -Mn-1 value at the amplifier 1, whereby he with the lying at the input of the circuit, positi = ven, the difference is zero. This will make the output of amplifier 1 as well the input of amplifier 4 is zero, and the first measured value is only in the capacitors 1o and 11 saved.

The first measured value disappears again at the input of amplifier ker 1: the trigger stage 2, which responded to the measured value, tilts back and gives as a result, a pulse is sent to the counter 7, which then switches to 2 ". The relay 12 opens again, then the relay 13 closes, and the transistor 14 becomes conductive ge = makes and discharges capacitor 10 via resistor 15.

The measured value still stored in the capacitor 11 (as negative voltage) Now comes through contact 13 to the input of amplifier 3 via the resistor 6, which is the same size as the Ge = gene coupling resistor 5, so that it is broadcast on a 1: 1 scale. Since there is also one from amplifier 1 via the Resistors 8 incoming value has a negative sign (inverted in amplifier 1), both are added in amplifier 3.

The second measured value appears on amplifier 1: This now forms its output is the difference between the 1st and 2nd measured value; since the counting decades meanwhile stand at "2", the resistor FET group is 8 by interrupting one Wi = resistance switched by its FET so that the effective resistance to the input of the amplifier 3 is twice as large as its negative feedback resistance 5.

As a result, the differential voltage supplied by the amplifier 1 is between second and first measured value only at half the size of that via contact 13 and resistor 16 still present at amplifier 3 first measured value added. The amplifier 3 thus supplies the mean value between the first and second measured value at its output. After the Zinstellzeit necessary for the amplifier 3 and the capacitor 1o the Entladetran = sistor 14 is blocked again so that now the mean value in the condenser sator lo remains stored. Then only relay 13 is opened again, then 12 closed and transistor 16 made conductive for a short period of time; through this takes over - via amplifier 4 - the capacitor 11 the mean value, which is now from the instrument 9 is displayed as the new value.

Turning on the transistor 16 must be done because of the new, from the output of amplifier 3 through amplifier 4 through the capacitor The value to be taken over can also be lower than the old value to which the capacitor 11 was previously loaded. The capacitor 11 can then be connected via the resistor 17 Discharged down to the new value, which is fed to it by amplifier 4. After the transistor 16 has been blocked again, the new voltage value remains at Capacitor 11 stands because its further discharge through diode 27 and the gate input of the FET 28 is prevented. The same also applies to transistor 14 the resistor 15 at the capacitor lo, disappears at the input of amplifier 1 of the the second and the third measured value appears, the switching sequence is repeated; from the amplifier 4 now comes the mean value displayed by the instrument from the first and second Measured value to amplifier 1, so that this is now the difference between the third M9ß = value and forms this mean value.

The counting decades 7 have now switched to 3 "and thus the FET's of arrangement 8 so that the resulting input resistance for the amplifier 3 is three times as large as the negative feedback resistance 5. This is in the amplifier 3 the mean value supplied via 13 and 6 from the first and second measured value only a third of the difference supplied by the amplifier 1 is added. You get consequently at the output of amplifier 3 and after pulling on relay 12 also at Amplifier 4 and the mean value of the first, second and third on the display instrument Measured value.

General: The nth measured value Wn and the negative mean value -Mn-1 from the previous measured values W1 to wn-1 are at the input of amplifier 1; the difference delivered by the output of the amplifier 1 therefrom, wn - Mn 1, is added by the resistor FET arrangement controlled by the counting decades 7 divided by n in the amplifier 3 to the existing mean value Da. The new mean value obtained from this from the measured values w1 to wn, is transferred from amplifier 4 to storage capacitor 11 and displayed by instrument 9.

The example shown in Figure 3 execution of the logical = rule Sequence circuit 18 works as follows: The input of the circuit is at the output of the Triggers 2, point 26; it receives voltage (L signal) as long as a measured value at point 25 is present. If the voltage is missing there (no measured value available), the Flip-flop 20 at its complementary output voltage, so that the transistor 14 is made conductive and the relay 13 picks up; Transistor 16 and relay 12 are off = switched off, since no voltage arrives from point 26 and above that the in this cable run, additionally attached to the relay 1,3 normally closed contact of the energized relay is open.

This is the state in the "pauses" between the measured values, such as indicated in the diagram of Fig.2. If a measured value appears and with it a voltage at the point 26, the flip-flop 20 switches over, i.e. transistor 14 and relay 13 off, however only after a through 'the charging time of the capacitor 22 via resistor 21 conding = th delay, which reduces the setting time for the amplifier 3 with the capacitor lo is observed. Only after the relay 13 drops out when its Normally closed contact closes, relay 12 picks up, and the monostable multivibrator 19 is for the duration of its proper time t voltage to the base of the transistor 16. The time t is dimensioned in such a way that the measured value from amplifier 3 passes through during its sequence the amplifier 4 is taken over and stored in the capacitor 11.

If the measured value disappears again, relay 12 drops out again; the also here effective delay of the flip-flop 20 by the BC circuit 21,22 ensures that transistor 14 and the relay 13 is switched on again, as requested.

This is the simplest connection option. Of course Relays 12 and 13 can - if the circuit is changed accordingly - through contactless switches, e.g. field effect transistors, are replaced; vice versa is the replacement of transistors 14 and 16, as well as the field effect transistors the arrangement 8 by mechanical relay contacts is also possible.

However, this simple arrangement still has one disadvantage, which is its own Questions about applicability in this form and therefore a further development makes necessary.

Each time a new measured value arrives, it must be in the capacitor 11 stored old value for the purpose of adding the corresponding new difference Computation amplifier 3 and then also 4 pass to then as a new mean value to be stored again in the capacitor 11. Each time they add up error of the secondary amplifiers to the stored value; after the hundredth reading the displayed mean value is therefore subject to 200 amplifier error amounts. The error amount of a connected computer amplifier is with today's means to keep the analog technology at about i% o; that gives a total error, depending on the sign position and the size of the errors in the amplifiers 3 and 4 and the number of measured values one "eie, on the order of 10 to 20%.

A further development of the arrangement described below for This error is reduced by taking the first measured value via a separate, direct way to save separately, while in the amplifiers 3 and 4 with the Capacitors 1o and 11 only add the difference amounts to one another, petcbert and during the whole series of measurements in a storage capacitor recorded first measured value is added via a further arithmetic amplifier = ker The large error sum of amplifiers 3 and 4 then does not occur as a percentage more of the measured value, but only of the mean difference of all values from the first MeBæ is worth in appearance and is therefore already around a power of ten relative to the measured value smaller, if @@ ch differentiate between the largest and smallest measured value by 20%, the difference The mean-extreme value is 10%. Are the readings in a row closer together, the error is correspondingly smaller; a more precise series of measurements thus also provides the more precise mean value.

If you take less than 100 measured values for a series of measurements, which is probably most of the time should be the case, the error becomes smaller in proportion to the number, since the Processing amplifiers are run through less often.

It is thus possible, with the more developed arrangement in general to achieve an error of 1% and less.

An example of a circuit arrangement that the above Be written performs, Fig.4 shows; in Fig.5 is the time sequence of the relays and in Fig.6 a Execution of a logic circuit for actuating the relay is shown.

In contrast to FIG. 1, FIG. 4:40 shows an arithmetic amplifier with a capacitor 44 and field effect transistor 42 for storing the first measured value; 41 a calculator more to the addition of the respective sum of the differences to the first value; 37 one Decoding circuit for counter 7, which only has the task of being at its output Signal n ° to be given if the counter is at "1" "and nL" for all others Meter readings, and only needs to contain the parts required for this. Circuits of this type are known and are therefore not further explained here. Holding on and Storage of the values given by amplifiers 3 and 4 in the capacitors 10 and 11 can now no longer take place via the valve action of diodes, because here only the differences between the individual measured values appear as voltages, which can be both positive and negative, so that both polarities are stored Need to become. Instead of the diodes 23 and 27 in FIG. 1, the diodes 23 and 27 in FIG Contacts 30 b and 31 b entered, which are actuated by the relays 30 and 31. These The function of the relays is comparable to that of the relays 13 and 12 in FIG. 1; she have to be made in such a way that the a-contacts only when they fall off close = Ben, if the b-contacts are already open. The same goes for that Relay 32 with contact 32 b on the one hand and contact 32 a and 32 c on the other hand. 38 is the logic circuit for actuating the relay, corresponding to Fig.1'18, their example = wise embodiment Fig.6 shows. The discharge transistors 14 and 16 of Fig.1 are no longer required, since the capacitors 1o and 11 are connected to the computer amplifier outputs discharge when contacts 30 b and 31 b close.

The mode of operation of this circuit is as follows: When the first measured value arrives, the counter is at "1" (S.Dia = gram Fig.5), relay 32 is briefly excited; it closes contact 32 b and opens 32 a, the amplifier 40 transmits the from the amplifier 1 delivered first measured value and charges the capacitor 44 until at the point 43 (source of FET 42) the same voltage is present as at point 45 (multiplied with the ratio of the two resistors 46 and 47, which is preferably 1: 1 or will choose a little differently). If the relay 32 drops out again, it opens Contact 32 b and closes 32 a, so the voltage on capacitor 44 remains.

The amplifier 4o is now inoperative; his input E-, before = before virtual earth, is held at zero potential by closed contact 32a. As a result, the load on the FET output, point 43, remains due to the resistor 47 in the same amount, so that the voltage transfer ratio of the FET 42 is not changed. The first measured value is thus stored in the capacitor 44; it is advisable to choose a MOS field effect = transistor for 42, the gate input of which has such a high insulation value that the voltage across capacitor 44 for the Duration of a series of measurements is retained with sufficient accuracy.

The stored first measured value taken at point 43 is taken from the computer amplifier 41 transferred to the display instrument 9.

So that it does not get to amplifier 1 from here and here immediately forms the difference with itself before the storage process in the capacitor 44 is completed, the relay 32 opens the contact 32c and this way thus interrupted until after the end of the storage of the amplifier 4o through the falling relay 32 is rendered ineffective.

If the first measured value at point 25 disappears, the counter switches 1 series on to and thus the resistance FET group 8 on division by 2 ", as in Fig.1. Otherwise nothing else happens.

The second measured value appears at point 25: At the input of amplifier 1 is now via the contact closed again by the relay 32 that has dropped out 32c also the first stored measured value, with a negative sign (the The measured value is at the output of the amplifier 41, on the instrument 9, because of the three times Polarity reversal in the amplifiers 1, 40, 41 as negative voltage, if he as positive voltage at point 25 = comes). Amplifier 1 now forms the difference from the second and first measured value; this remains ineffective at the amplifier 40 as a relay 32 no longer attracts; but it comes, in the same way, from the resistance group 8 divided by two as in Fig.1, to the amplifier 3, which it in the capacitor lo stores the first measured value in the cord in the same way as described above Sator 44 has been secured (relay 30 is picked up, relay 33 not yet; a Any test voltage still present in capacitor 11 can therefore not be applied to the The input of amplifier 3 get there, where they get the difference value coming from 8 would falsify). After a time that is sufficient for storage in Korden sator 1o, Relay 30 drops out, as a result of which the amplifier 3 is rendered ineffective and the difference value is held firmly in the condenser 1.0. After relay 30 drops out, relay pulls 31, whereby the amplifier 4 is switched on. The difference is worth it transferred to the capacitor 11 and also stored there. At the same time pulls Relay 33 on; the difference value stored in the capacitor 11 reaches its Contacts once to the input of the amplifier 41, is there to the already stored, the first measured value taken from the point 43 is added, so that the amplifier 41 now the mean value of the first and second measured value on the display instrument 9 and the Input of amplifier 1 emits. On the other hand, the difference value comes over the second contact of relay 33 also to the input of amplifier 3, but - because of the dropped out relay 30 - not yet reacted to this. The instrument 9 shows the mean value of the first and second measured value.

The second measured value disappears from point 25; Relay 31 drops away, this makes amplifier 4 ineffective, as a result of which the difference value in capacitor 11 is retained will. With a short delay, relay 30 then picks up again, so that amplifier 3 again is switched on. At its input there is now the relay via the energized relay first difference value to which the capacitor 10 is still charged from before; initially nothing changes in its condition. The counter switches on "3". The third measured value appears at point 25: Amplifier 1 now forms the difference between the third measured value and the mean value of the first and second measured value, which is fed to it from amplifier 41 via contact 32c. This difference is as in Fig. 1, from group 8 now with a third of its value to amplifier 3 passed on. It is there to the also present, stored in capacitor 11 = th first difference value is added, so that the capacitor 10 is now based on the sum of these two differential values is reloaded.

Shortly thereafter, relay 30 drops out. The new one is in the capacitor 10 held; then relay 31 picks up; the new difference = value will be from capacitor 11 thernomnen and fed to the amplifier 41. The amplifier 41 is now receiving the difference between the second and first measured value, divided by 2, and the difference from the third measured value and the mean value between the first and second measured value, through 3 divided, added as a sum and added to the first Mel3wert.

The mean values from the other measured values are now the same Way educated.

Fig. 6 shows how the relays can be switched. The relay 30 and 31, which in their function correspond to the relays 13 and 12 in FIG operated in the same way as shown in Fig.3, but only when the counter is at "2" and the AND gate 48 of the second measured value and of the decoding 37 L-signal receives (the first measured value is supposed to go the anceren way); remains before Relay 30 energized, 31 de-energized. The first reading is via the N I C H T link 49 together with the zero signal from the decoding 37 via the OR-NOT element 50 and the capacitor 52 a voltage surge to the relay 32, so that the = sen picks up briefly, whereby the measured value can be stored in capacitor 44 (Diode 51 prevents the relay from picking up again when the voltage is applied at the exit of 50 disappears again; Resistance 53 allows the discharge of capacitor 52; instead of the capacitor circuit one could also control the relay via a monostable multivibrator). Re = lais 32 pulls through it only briefly at the first measured value and then no longer during the entire series of measurements.

Relay 33 should only pick up at the second measured value: It is therefore from L signal made dependent on the decoding that appears after the first measured value; in addition, it is controlled via a contact of relay 31 (31c), which is the first at the second measured value, after relay 30 has dropped out, picks up. Via a self-holding con = takt (33a) it then remains attracted during the entire series of measurements, as required.

The basic position of the counter is "1", not zero. The counter receives a reset (to be actuated by hand in the event of premature termination of a series of measurements), which switches it to position I11 (not shown in the figures). The position Zero can be assigned to the hundredth measured value.

Publications considered: F.Donaubauer, H.Lucius and G.Negele: Computing amplifier, part 3, electronics 15 (1966), volume 8, pages 251-252 K.F. Zeine: A peak voltmeter for one-time, short-term processes.

Electronic Rundschau 1959, issue 10, pp.365-366 Own patent application Rectifier circuit for charging a capacitor to peak values more time-dependent Voltage curves.

p 15 91 876.0 v. 7/25/67

Claims (9)

Claims. 1. Circuit arrangement for the direct display of the mean value of measured values a series of measurements, characterized in that each time a new measured value is received, the saved, from the measured values that have already arrived on the same Average value formed by the number of measured values that have already arrived divided difference between the new measured value and the previous mean value is added will. 2. Circuit arrangement according to claim 1, characterized by = nest, that to divide the difference value an electronic or electromechanical Counter counts the number of incoming measured values and overcomes it with its outputs mechanical relay, transistor or field effect transistor switch the resistor circuit an arithmetic amplifier that receives the differential voltage so controls that the gain factor of this computing amplifier corresponds to the respective counter reading corresponding divider ratio. 3. Circuit arrangement according to claim 1 and 2, characterized in = characterized that the processing amplifier according to AnsDruch 2 (3) by supplying the respective previous Mean value (Mn 1) over a further input resistor (6) at the same time = at the same time Addition of the difference divided by n to the previous mean is used will. 4. Circuit arrangement according to claim 1 to 3, characterized = zeiehnet, that the computing amplifier according to claims 2 and 3 (3) is connected as a peak value memory which stores the mean value in a capacitor (1o). 5. Circuit arrangement according to claim 1 to 4, characterized in = characterized that a further, as a peak value memory switched computation amplifier (4) is available which takes the measured value from capacitor (5) and stores it in its capacitor (11) stores from where it is sent to the input amplifier for the purpose of forming the difference with the next measured value the arrangement (1) and the amplifier to add the difference divided by n (3) is fed. 6. Circuit arrangement according to claim 1 to 5, characterized in = characterized that by a logic circuit (1ß) by means of mechanical or contactless switches (12, 13, 14, 16 take over the mean value formed in amplifier (3) Amplifier (4) and the return of the amplifier (4) in the capacitor (11) stored mean value (Mn-1) for the purpose of forming the next (Mn) by addition the difference (wn - Mn-1) divided by n to the amplifier (3) in the correct Sequence is controlled, and that the operation of the logic circuit (18) by the arrival and disappearance of the order at the entrance (funct 25) supplied measured values, preferably by a trigger circuit (2). 7. Circuit arrangement according to claim 1 to 6, characterized in that that the first measured value separately in a capacitor (44) for the duration of a series of measurements stored and fed to a further arithmetic amplifier (41), at the output of which the display instrument is connected, and that in the amplifiers (3 and 4) with the storage capacitors (1o and 11) only add the difference amounts to each other, stored and also fed to the computing amplifier (41) to which it is used The first measured value is added and the sum of this as the respective mean value is added to the display instrument feeds. 8. Circuit arrangement according to claim 1 to 7, characterized in = characterized that the control of the incoming measured values, the first for direct storage in the capacitor (44), all others for forming the difference and adding up the difference transfers through the amplifiers (3 and 4) through relays or contactless switches through a to the counter (7) connected decoding circuit (37) takes place, which takes place when the counter reading emits a different signal for the first measured value than for all other counter readings. 9. Circuit arrangement according to claim 1, d.g. that the storage of the Average value, the formation of the difference between the incoming measured value and the stored one Mean value, the division of the difference value and the addition of the divided difference to the present mean value or a part of these functions through a digital one Computation circuit is made.