DE2554190C2 - Magnetic compass - Google Patents

Description

circuit is used, the direct currents to the magnetic field detector of such a size that the earth's magnetic field detector is compensated. By This zero adjustment results in an extremely high accuracy of the magnetic direction display, there are however, no means of compensation whatsoever for the changing strength of the earth's magnetic field in the output signal provided and the use of gain control devices of the type described in the opening paragraph Art again runs the risk of introducing additional compass errors.

The invention is based on the object of creating a magnetic compass of the type mentioned at the outset, whose output signal is independent of changes in the strength of the magnetic field. whereby on the one hand by the Evaluation circuit no additional two-period compass errors should be introduced and on the other hand circuits provided to compensate for compass errors do not change the output signal should cause.

This object is achieved in a magnetic compass according to the preamble of claim 1 by the in its characterizing part specified features solved

Advantageous refinements and developments of the invention emerge from the subclaims.

The design of the magnetic compass according to the invention results in a compensation for changes the strength of the magnetic field, without a partial block diagram representation by FIGS. 1A and 1B the essential components of an embodiment of the magnetic compass and the electrical connections these components with each other;

F i g. 2 part of FIGS. 1A and 1B, the automatic Gain controller of the magnetic compass is shown in more detail.

3 shows a detailed circuit diagram of an index angle error compensator according to Fig. IB;

4 shows a detailed circuit diagram of the also in Fig. 1B shows two-period compass error compensation means;

F i g. 5 is a block diagram showing a modified embodiment of the magnetic compass according to FIG. 1A and IB shows.

In Figures IA and IB the magnetic compass closes a magnetic field detector in the form of a magnetic field probe 11, which is fed from an alternating current source 2 which can be formed by a conventional 400 Hz oscillator or signal generator and which with an excitation winding 12 of the magnetic field probe is coupled.

The magnetic field probe 11 has three inductive windings 13, 14 and 15 operated in a star connection on a corresponding star-shaped core, the individual legs of the winding being brought together to form a common earthed connection F. The connections of the windings 13, 14, 15 removed from the connection F are each labeled A, B, C in FIG. 1A

the compensation devices additional two-pipe 30 denotes. If period compass errors are introduced to the terminals A, B, C , which is also desirable, one-period compass error compensation for compensating compass errors provided tion signals from a (not shown) one-period circuitry no change in the output signal of the universal, common type, as described in the British patent 8 50 692 will see in the magnetic compass according to the invention. The use of a simple common circuit A of the magnetic field probe 11 is not only compensated for the capacitor 16 with an end of a first input effect of the changing strength of the geomagnetic winding 20 of a Scott-T transformer 21 connected field via a separating automatic gain control, but In addition, while the connections B and C are corrected via the respective effects of other sources of error, the errors of known systems are reintroduced without 40 isolating capacitors 17 and 18 with the respective enda3, that of a second input winding 22 of the Scott-T. In the magnetic compass according to the invention
are the input signals to the utility facilities
monitors itself and not just the output signals of the magnetic field detector. So not only will
Changes in the strength of the earth's magnetic field, rather
also compensates for changes in gain caused by
Changes to component parameters and other effects
without introducing new errors

45

will.

According to a preferred embodiment of the invention, network devices that are electrically cross-connected result a correction for the two-period cardinal compass errors in the sine and cosine channels of the magnetic field detector signal evaluation system by setting only one setting device. A similar arrangement, again requiring only a single adjustment, is used for the Correction of any index angle error used transformer 21 connected. The winding 22 has a center tap connected to the other end of the winding 20.

As is well known, the output signals of windings 13, 14 and 15 have a frequency equal to is twice as large as the frequency applied to the excitation winding. The frequency doubled cosine output a winding 23 of the transformer 21 and the frequency-doubled sine output in one Windings 27 of this transformer are connected to a current feedback loop 31. Additionally will the output of a frequency doubler 29 is fed to the current feedback loop 31 via the line 29a because the frequency doubler 29 is fed from the source 2, its output in the line 29a has a frequency of 800 Hz and this output serves as a reference signal source for the feedback loop 31.

How this is more fully described in British Patent Specification

In a modified embodiment of the grain ω 12 91 597 is described, the current feedback compensation system provides these latter two grain loop 31 outputs to two lines 32 and 33, which

pensations by direct current signals carried out in given proportions directly the inductive Windings of the magnetic field detector are supplied.

Embodiments of the invention are explained in more detail below with reference to the drawing the drawing shows

65 are direct current signals, the amplitude of which is proportional to the sine and cosine of the magnetic heading

(H _m sine ψ + H _n , cos ψ) of the vehicle. The hori-

zontalkomponenlen of the magnetic field measured by the magnetic field special windings 13, U 1 and 15 resolved into sine and cosine component values, which are then converted in the current feedback loop 31 into proportional direct currents on the lines 32 and 33. As it is described in the above-mentioned British Palentschrift 12 91 597, these direct currents are each returned via two lines 10 and 10a into the windings 13 and 15 of the magnetic field probe 11, these currents trying to cancel the earth's magnetic field present here. The feedback arrangement and the many advantages resulting therefrom are fully described in the aforementioned British Patent 12,91597, including closed loop operation which gives high accuracy outputs in the form of DC analog outputs proportional to sine and cosine of the vehicle's magnetic heading.

Correspondingly, the 800 Hz three-phase magnetic azimuth information derived from the horizontal magnetic field detector or the magnetic field probe 11 is converted into direct current signals proportional to the sine and cosine of the heading of the vehicle by the interaction of the Scott T transformer 21 and the current feedback loop 31. The sizes of the outputs on lines 32 and 33 are thus a function of the magnetic azimuth direction or the heading of the vehicle and the intensity of the horizontal component of the earth's magnetic field. The change in the size of the sine and cosine outputs caused by any change in magnetic field strength Hm only affects the output gradient (volts per azimuth degree) and does not change the trigonometric relationship of the magnetic input heading angle ψ and the output voltages of the current Return shipments 31, which can therefore be expressed as follows:

V32 = ATj sin ψ
V33 = Κ · \ cos ψ

where K \ takes into account the gain of the current feedback loop 31 and has the dimension of volts per oersted.

Signals V32 and V33 on lines 32 and 33 serve as two inputs to an automatic gain control circuit 34, which continues to receive the particular sienale which is fed back on two lines 56 and 57 will. As will be explained further, the feedback signals arise at the outputs of the Buffer amplifiers 52 and 53 (Fig. IB) after the outputs the automatic gain control circuit 34 is processed at least in a double-channel modulator 45 became. In order to understand the operation of the gain control circuit 34, the presence the index error compensator 37 and the two-period compass error compensator 48 are initially neglected for reasons of simplicity.

The final output of the compass system, which is supplied via lines 61, 62 and 63 to an aircraft navigation system or other utility 64, must typically be useful in a three-phase synchro-transmitter system and must consist of proportional voltages between pairs of such lines such as z. B. between lines 61 and 62, 62 and 63, 63 and 61 exist. These may be nominally 11.8 volts, for example, and must be kept on a constant gradient in order to maintain the required compass accuracies over a wider range of horizontal magnetic field strengths Hm . Because the output of the magnetic field probe 11 and thus the output of the current feedback loop 31 has a gradient, the size of which is directly proportional to the horizontal magnetic field strength, which of course changes with the latitude, the automatic gain control circuit 34 must the output signals of the system on the lines 61, Maintain 62 and 63 at the desired constant thigh-thigh gradient of nominally 11.8 volts.

To this end, the DC outputs on lines 35 and 36 of the gain control circuit 34 fed to the usual double-channel modulator 45, each of the two separate channels the 400 Hz reference signal of the source 2 is fed to this modulator via a line 2a. The DC signals on lines 35 and 36 are modulated with the 400 Hz alternating current signal in the usual way, so that 400 Hz signals appear on lines 46 and 47, proportional to the sine and, respectively Cosine of the aircraft's magnetic heading. After separate and independent feeding equally amplified versions of these signals appear to buffer amplifiers 52 and 53 the lines 54, 55 to which the return lines 56 and 57 are connected.

The automatic gain control circuit 34, which is shown in greater detail in FIG. 2 monitors the Gradients on the output lines 54,55 of the buffer amplifier 52 and 53, the result compares with a Reference voltage level and then changes the system gain accordingly by controlling the gain of the automatic gain control circuit 34. When the gradient at the outputs of the buffer amplifiers 52.53 according to FIG. 1A smaller than a given one Level is, the voltage gain of the circuit 34 is increased to the output of the buffer amplifier 52.53 to the correct level. The output of the buffer amplifiers 52, 53 and the voltage gradient is controlled in the same way. The signal levels on the output lines 35,36 of the automatic Gain control circuits 34 are ultimately via a Scott-T output transformer 60 led. The outputs of the transformer 60 are therefore entirely dependent on the change in the field strength of the earth's magnetic field independent. So is:

V35 = K2 sin φ
and
V36 = Κι cos ψ

where £ 2 is a new constant of proportionality

The automatic gain control circuit 34 is constructed to introduce any zero deviation or an asymmetry between the transmission channels, which leads to periodic errors would be prevented in the aircraft's heading output data. The individual reinforcements the sine and cosine channels are now controlled in the same way and there are no offset voltages The DC signals induce the sine and cosine of the vehicle's magnetic heading represent. As is explained in more detail in FIG. 2 to

9 10

is known, the direct current signals to the line 400 Hz excitation signal from the generator source 2 connections 32 and 33 is previously passed through the interaction. Under the control of its one of the magnetic field probe 11, the Scott-T transformer 21 input supplied direct current with variable and current servo loop 31 is generated and its amplitude and its second input supplied amplitude are proportional to sine φ and Ko- The 5th alternating current with constant amplitude acts sinus y>. The output line 32 is in series via one of the amplifiers 87, usually a variable pulse resistor 75, a connection point 76, a generator having a width for supplying a state 77 and an input line 35 to a first 400 Hz signal with a variable pulse width guided on the channel of the double-channel modulator 45. A connection point 74.

Capacitor 78 is connected between line 35 and earth 10. The filter, which has a variable pulse width, forms a low-pass filter with the signal being connected in parallel from connection point 74 from stand 77. In the same way, the second output is via two respective resistors 85, 86 the base electrical line 33 in series through a resistor 79, a troden of the chopper transistors 83 and 84, junction 80, a resistor 81 and a. to control the relationship between the conductivity and input line 36 to the second channel of the double channel 15 blocking times of these switching transistors. The NAL modulator 45 is performed. A capacitor 82 is between transistors 83. 84 are switched on synchronously with the dike time leischen line 36 and earth and forms tend and are then both non-conductive, namely for one with the resistor 81 a low-pass filter. Switching or controlled time period depending on the pulse chopper transistors 83 and 84 are respectively of the width of the output of the amplifier 87. When the connection points 76 and 80 are connected to ground 20 non-conductive part of the period in terms of time duration and control the flow of current through their emitters - and KoI- is increased, then the total current per period is biased from the line 32 to line 35 according to their respective base electrodes. gets enlarged. In other words, the direct current signals on lines 32 and 33 form a proportionally smaller part of the current available on line 32 are chopped up by transistors 83 and 84 and 25 are diverted towards the end after smoothing in by the resistor - will. In this manner, the voltage between ö "ü capacitor combinations 77, 78 and 81, 82 gebilde- lines 54,55 independently of any Ampliten low pass filters direct currents, is separated in the tudenänderungen in the entire magnetic field probes dual channel modulator 45 with the 400 Hz Bezugssi - Data system and amplitude changes are modulated independently on line 2a. These double 30 pending, which result from other interference factors in channel output voltages, are transmitted via the Scott-T signal channels between the current servo loop 31 transformer 60 as three-wire synchronous data to and the buffer amplifiers 52 and 53 result. Entspre navigation system or other utility device is accordingly the three-wire output of Nutzeinrich-64 forwarded. _tung 63 _by ρ i g. 1B by the transformer 60 supplied-to control the automatic Verstärkungssteu- 35 leads, essentially from leg to leg circuit 34 the same are modulated with 400 Hz kept at a constant value, for example to Iaten output currents on lines 54 and 55 ll, 8Voit

In the complete system, as shown in FIGS. 1A, resulting in amplitude and a variable phase and shown in _{FIG. 1B, the outputs V 1 and K 36} circuit comprising a resistor 95 and a capacitor 40 of the automatic gain control circuit 34 can be fed to the generator 96, which is connected in series to the lines 56, 57 the Lines 35 and 36 are first switched on at the index angle and form a connection point 97 with error compensator 37 prior to modulation at 400 Hz. Which are processed by the resistance condensate. For this purpose, the comtor combination 95,% formed circuit is from the compensation circuit according to FIG. 3 used. The index of the general kind, as described in US Pat. stands, a perfect alignment between the longitudinal transmission signal at the connection point 97 is rectified with an axis of the aircraft and the effective electric diode 94 and appears as a variable longitudinal axis of the magnetic field probe 11 to achieve, unidirectional voltage at an input of a 50. The index angle is accordingly -Fault compensator usual integrating operational amplifier 92, des- 37 provided to carry out a manual sen output via a capacitor 91 for the same correction after the installation of the system thereby returning to input. At the second input of the enable that essentially the same function of amplifier 92 is carried out via a resistor 93, a stable one, as it results from a relatively expensive unidirectional reference voltage from a 55-digit servo differential, which is suitable for some known (not shown) Source created that was used with systems. However, because the fitting is connected to the connector 98, as shown in FIG. 2 shown accuracies are usually within ± 10 °, the amplifier 92 and its associated can act the compensation function precisely with the help of the circuit as a conventional comparison device in order to determine the output gradient on the lines in the result of the relatively inexpensive circuit according to FIG 54, 55, 60, in which only a single Pom with the fixed voltage level at connection 98 has to be set to the tentiometer shaft. It is to be compared, with an integrated output as radio know, that the correction of the described Comtion of the difference between the two voltage levels at the compensation device in the value of the angle φ results in the connections 97 and 98 is carried out if this is still in the trigonome -

The positive signal at the output of amplifier 92 is 65 fresh form of sine ψ and cosine ^ data

The device according to FIG. 3 receives an input of a corresponding via a resistor 88

Amplifier 87, the other input of which is connected to two inputs K ₂ sine φ and K ₂ cosine ψ and

A connection 90a and a resistor 89 internally produce two values

11th
- Κι β · cosine ^ and - fo / ^ sine yi.

The K ₂ sine ψ- value and the - to form K ₂ cosine β ψ- value are added according to the well-known trigonometric equation to K ₂ sin (φ + β), can be used wherein ψ '= φ + / to? to represent a corrected value of φ . The K ₂ cosine ψ value and the -K ₂ β sine ψ value are added in the same way to form the K ₂ cosine (ψ + β) . The / ^ expressions must be identical in both the sine and cosine output channels in order to perform accurate compensation. Hence the same source for the / S 'term is used in the two channels of the circuit.

In detail, negative DC voltages representing K ₂ sine φ and K ₂ cosine ψ are fed to the circuit according to FIG 145 and 155 which are shown near the right-hand side of Figure 3. The two same negative DC voltages are used in the remainder or greater part of the circuit in order to generate compensation voltages which are also input to the amplifiers 145, 155. For the latter purpose, the —sine φ- term on line 35 is fed to a switching transistor 107 via a conventional inverting amplifier 103. The output terminal 104 of the amplifier 103 is connected to its input terminal 101 via a resistor 102 and, in addition, a second input terminal of this amplifier is via a resistor 105 connected to ground. The - cosine ψ- term on the line 36 is fed directly to a switching transistor 109. The transistors 107 and 109 are alternately made completely conductive and completely non-conductive, so that first the output of the transistor 107 appears on a line 108a and then that of the switching transistor 109 forwarded signal appears on line 1086. Because both lines 108a and 1086 are connected to an adjustable wiper 113a of a potentiometer 113, it can be seen that the signals forwarded by the switching transistors 107 and 109 are alternately fed to the wiper 113a in order to be on a time division basis an amplifier 120 to be amplified.

The switching transistors 107 and 109 are alternately rendered conductive under the control of a sinusoidal oscillation signal on a line 26 and this signal is expediently obtained from the 400 Hz source 2 according to FIG. 1A, although other conventional signals emitting a stable frequency can alternatively be used. In practice, the 400 Hz period signal is supplied on line 2b via line 106 in order to control the conductivity of transistor 107. So that an operation on the basis of time division can be used, the signal on the line 2b is fed via a line 111, a 180 ° phase shifter 112 and a line 110 for controlling the operation of the switching transistor 109

In this way, the signals on lines 35 and 36 are alternately sent to the selected contact point of the potentiometer 113 is applied, its opposite connections 1136 and 113em with the inputs of the operational amplifier 120 are connected. The output terminal 121 of the amplifier 120 is via a Resistor 115 connected to its input at terminal 1136, while terminal 113c has a Resistor 114 is connected to ground in the usual way. The input of amplifier 120 is therefore on operated on a time division basis and its output at terminal 121 becomes a second pair of switching transistors 122,123 which are arranged so that they enable the series signal flow through the respective resistors 126,127 to control amplifiers 128,129. The effective gain of amplifier 120 becomes accordingly the setting of a single actuator 37a changed by hand according to the known size of the index error is set as a result of the usual swing of the compass system is determined on the ground.

The conductivity of the switching transistor 122 occurs simultaneously with the conductivity of the switching transistor 109 on. In the same way, the switching transistor 123 becomes simultaneous with the conduction periods of the switching transistor 107 made conductive. This operation is achieved by increasing the conductivity of the switching transistor 123 is controlled in accordance with the signal on line 26, which is transmitted directly to switching transistor 123 via a line 125 is supplied. The desired synchronous operation of the switching transistor 122 is thereby achieved that the phase shifted by 180 ° signal from the phase shifter 112 via a line 124 the Switching transistor 122 is supplied. In this way, both channels use the circuit on a time division basis the common amplifier 120, whereby it is ensured that identical corrections to the applied to both channels, d. H. that the size of the sine term that adds to the cosine term is identical to the size of the cosine term that is subtracted in the sine channel. It can also be seen that the setting of a single actuator 37a the setting of the Potentiometer 113 allows both channels in an identical manner according to the size of the idex error are set.

The currents occurring on a time-division basis, which alternately flow through the switching transistors 122, 123, are alternately fed to the usual amplifiers 128, 129, which have a gain of 1, and the respective outputs at the terminals 132, 133 flow through resistors 141, 150 to the same respective ones Input terminals of the amplifiers 145, 155, which are connected to the respective lines 35, 36. the Outputs of amplifiers 145 and 155 can be smoothed by the action of suitable low pass filters remove any 400 Hz modulation from the outputs appearing on the respective output lines 38, 39 occur. In the illustrated embodiment the filters are arranged at the inputs of the amplifiers 128 and 129 and comprise resistors 126, 127 and capacitors 128a, 129a, respectively.

The mathematical relationship showing the index error as a function of the sine and cosine of the magnetic The heading is:

tan- '

wonn

ψ ' ψ β

the compensated output
the uncorrected input,
is the tangent of the index error

Therefore, by adjusting the gain of the time division amplifier 120 accordingly of the value of equation (5) can be satisfied as follows: The output; .ng of amplifier 128 is:

when the transistors 109 and 122 are conductive, and the The output of amplifier 129 is:

= - Kißsin ψ

when the transistors 107 and 123 are conductive. The addition at amplifier 145 results in an output:

Vie = K ₂ (sin φ - ^ cos φ)

while the addition at amplifier 155 has an output:

V39 = K ₂ (cos ψ + /? Sin ψ)
generated or

V38 = K ₂ sin ψ 'V ₃₉ = K ₂ cos ψ'

These DC signals are ready for conversion in the dual channel modulator 45 because they are DC signals in terms of ψ ' and contain the desired index angle error compensation according to equation (5). The double-channel modulator 45 therefore supplies signals at 400 Hz on its output lines 46, 47, the amplitudes of which are as follows:

V ₄₆ = K ₃ sin φ '
V47 = K ₃ cos φ '

These signals then serve as inputs for the two-period Kempaßerrachungseinrichtung48.

The two-period compass error in a magnetic field probe including a probe after The type of magnetic field probe described here is due to the presence of a soft iron mass or - caused masses in the vicinity of the magnetic field probe, causing the surrounding earth's magnetic field to adhere to it Magnetic field probe is distorted. As the name suggests, this error is a sinusoidal error and has two complete periods within an azimuth rotation of the vehicle by 360 °. Generally determined the mean position of the soft iron mass relative to the magnetic field probe the direction of its effective vector. For convenience, the two-period compass error compensation is used performed by effectively dividing the total vector into orthogonal components, one of which is called cardinal or Major heading bi-period compass error component, while the other is called the Called the intercardinal or inter-directional compass error component. The cardinal two-period compass error has extreme values at heading angles of 0 °, 90 °, 180 °, and 270 °. The intercardinal Two-period compass error, on the other hand, shows extreme values at azimuth angles of 45 °, 135 °, 225 ° and 315 °. In Fig.4, the latter error simply corrected by the fact that an adjustable serial

Resistance 199 is placed in the negative feedback branches of the AC amplifier 200, which is caused by the Line 46 is controlled. Adjustment of the actuator 486 according to the data obtained during the swinging of the compass system during installation are obtained then corrects the output on line 50 as appropriate. The intercardinal Two-period compass errors are compensated for by eliminating the gain symmetry between the Sine and cosine channels which provide the outputs on lines 50 and 51, respectively.

The correction of the cardinal or main direction compass error is carried out by the simple circuit according to FIG. 4 is carried out using a single setting actuation controller 48a and a common circuit stage in a manner which largely reduces sources of error and which is characterized by great simplicity. The size of the setting eier actuator 48a is also determined by the swing of the compass system when installed on the ground. The signal K ₂ sine φ 'on the line 46 is fed via a line 175 through resistors 177 and 18frden respective inputs of a differential operational amplifier 188 supplied, the value K ₂ cos φ' of the conduit 47 is connected through a resistor 178 to the terminal 183 to the Channel K ₂ sin ^ expression is added and in the same way the expression K ₂ sin ψ; 'from the line 46 via the resistor 180 at connection 185 to the K ₂ cos ψ expression is added between the output 189 of the amplifier 188 and its Input terminal 183 is a resistor 187 switched on in the usual manner A variable resistor 186 with adjustable actuator 48a is connected between terminal 185 and ground The variable resistor 186 is the only means of setting the cardinal compass error and its change affects the effective gain / des Amplifier 188. Corresponding to the setting of the actuating device 48a, a compensation voltage appears at the output 189 of the amplifier 188:

—Y (s \ n ψ '+ cos

The signal value Vigg is connected to branching lines at the connection point 190 in order to feed this signal via the resistors 192, 193 to the inputs of the respective amplifiers 200 and 201. As mentioned earlier, the amplifier 200 has a variable resistor 199 connected between its output 203 and its input line 195. The other input of amplifier 200 is connected to ground via a 1% resistor. The signal K ₂ cos ψ 'is fed to the further amplifier 201 from the line 47 via a resistor 194, and this amplifier similarly has a resistor 202 which connects the output 204 to the input line 197. This amplifier uses one in the same way Resistor 198 connected between a second input and ground. The amplifiers 200 and 201 serve as adding and inverting circuits via the respective connection points 195 and 197, so that the correction expression appearing at connection 190 is added to the Ki · sin ^ 'expression on line 46, and the summation expression occurs the output line 50 on. Similarly, the Ki cos ^ 'signal on line 47 is applied to the compensation

25 34 190

15 16

tion signal at the connection point 190 with HiKe of the mentioned figures are not shown with BeVerstärkers 201 and the associated circuit additional numbers above 300. It is to be added and there is an inverted signal on the knowledge that the embodiment according to F i g. 5 similar duct 51 generated In this way, the chip is borrowed like that according to FIGS. IA and IB in series _{arrangement V »equals: 5} a reference signal generator or a source 2,

a magnetic field _{probe H 1} , isolating capacitors 16, 17

Vx m Ki [Ua φ '+ y (w φ ¹ + cos φ)] (15) and 18, a Scott-T-Trunformator 21, a current

Feedback loop 31, an automatic gain

while the voltage on the output line. 51 control device 34, a double channel modulator 45, same; to power amplifiers 52 and 53, an output Scett-T

Use transformer 60 and a utility device 64

Vsi - Ka [cos yf + ^ (sin ψ + cos φ * β (1 &) det In a manner similar to that of Fig. 1A with respect to the

Lines 10 and 10a used is similar,

the respective correction currents are summing point

In equations (15) and (t6), the new value ts th 320,321 according to FIG. 5 supplied so that they include the effect of the setting of the resistance of the respective leg of the magnetic field probe 11 to earth 199 by the Κ *. Therefore, the voltage at the output line and through the capacitors 16, 17, and 18 output line 50, equals sin φ " and the voltage at which is prevented from entering the Scott-T transformer output line 51 is cos ψ", where tp " the value ψ ¹ 21 flow.

corrected for both cardinal and interkaKfiaal- a> In the lower part of FIG. 5 is the index-Kompen-Kompassfehfer represents From equations (15) and; sation device 37 shown schematically The Ahn- (16) it can be seen that the value of the corrected »Wia-. possibility with the corresponding arrangement according to fig. 3 kels v 'is expressed by the following equation: can be recognized immediately, as is the simplification

can be seen in the illustration
Di d di i

ν " '- tan-' Ο + ft} · *" ¹ tf '+ ^ ⁰⁰ S ^ t \ j \ ^{v This means} that the sines ψ- and cosines ^ equals-

^ (Γ + ^ cos y '+> »siä ψ Y' current signal outputs of the current feedback loop 31

on the lines 32 and 33 alternately after the

ψ ' represents the final »output & heading compo-inversion of one signal in an inverter 340

nents. the. against cardinal and intercardinal two- the input of a variable gain on-

She corrects period compass errors. It can be recognized by the amplifier 120a via switching devices

NEN, that the amplifier 188 is supplied with its effective amplification 300 which is applied to the transistors 107,109 of FIG. 3

kung ^ correspond to the variable FWW * by the setting. As shown schematically, the

tiometers 186; is set, so acts in the circuit. Reinforcement of the reinforcement 120a with the help of an input

that the function ν (sin φ '+ cos φ) is generated and this setting button 37a is controllable, which generally controls the

Function is in the sine and cosine lines by 35 control of the amplifier 120 of FIG

the respective action of amplifiers 200 and 201 and button 37a and potentiometer 113 accordingly

their associated circuits add * ddk: rt It is to the value β corresponds to the output of the amplifier

recognize that the correction of the cardinal two-perimeter 120a will alternate in the same way on two

dull compass error by manually operating a branch line as in FIG. 3 with the help of a switch

single adjustment device is carried out. Further- 4 »301 switched, which generally corresponds to the transistors 122, 123

the only one with the amplifier 188 reduces according to FIG. 3 corresponds to the control of the switches 300

Bound level possible sources of error as far as possible and 301 according to FIG. 5 is the same as in FIG. 3, she is

borrowed and contributes schematically to simplify the setting process, however, for reasons of simplicity

at. 5 represented by switch control devices 302

In the Ausföhrungsbeispisl according to FIGS. 1A and 45, which is generated for example by the 400 Hz source 2

IB will be the index compensation and two-period controls. In Fig.3 the outputs of the

the compass error compensation signals from the Si transistors 122 and 123 two branch circuits

ims and cosine outputs of the current feedback including amplifiers 128 and 129

Loop 31 generates uiid again downstream in leads to the original sine ψ and cos ψ

The two channels are fed to their original "- so direct current outputs of the current feedback loop over

borrowed or uncompensated values are summed to modify the amplifiers 145 and 155 or to use

will. this to be summed up. On the other hand there will be two

In the modified embodiment according to the output branches of the switch 301 according to FIG. 5 corresponding to Fig. 5, the sine * and cosine outputs of the correspondingly applied to the direct current flow for supply current feedback loop 31 essentially in the same way 55 of compensation currents in the correct ratio to the way used to the compensation signals 120 ° offset inductor windings 13,14 and to generate direct current signals. To control the summation 15 of the magnetic field probe 11 in order to have one of these signals with the original data, each summation with the original sources is carried out directly on the magnetic probe H for the sine ψ and cosine signals of the current carrying the compensation signals as direct currents 60 to achieve feedback loop 31. In Fig. 5, this in the Magnetfeldsojiden-legs are even attributed DC conditions by the selected Wiwerden, as a result, the output resistances of the magnetic 303,304 and 305 nits in the illustrated behaves field probe itself basically in accordance with the con- determined The currents from the resistors 304 \ concept of The above-mentioned British patent specification and 303 are attached to the magnetic field probe winding 15 8 50 692 is compensated. 65 led while the current from the resistor 303? '

In Fig. 5, the same reference numerals are used to designate the magnetic field probes · winding 13 is supplied. |

of elements used the elements according to the If desired, two resistance ||

F i g. 1A to 4 correspond. Elements that advertising Ü used in these ultimately capacitor circuits 306 and 307

17th

to be supplied to transient effects of the switches 300 and 301 and 15 of the magnetic probe 11, so that to decrease. the intercardinal two-period compass error correction

Thus, the device according to FIG. 5 is used in one of the correction signals effectively with the magnetic field probes Wicknach F i g. 3, an index error output is summed up, which contributes to the output compensation through the time division of a single amplifier 120a between the sine ψ and cos φ-Κζ- Correspondingly, the modified execution

by alternately operating the switches 300, approximately in the form of FIG. 5 to achieve the index and the two-cycle 301, the amplification of the amplifier oden-KompaBerrensälungssignale from the Si-120a by the single control element 37a in accordance with nus ψ and cosine y direct current outputs of the size of the error is controlled. This operating 10 current feedback loop 31 generates and then back to weise ensures that the size of the sine ^ current is fed back to the correct magnetic field probe inductor windings in the proportions required for the magnetic field probe windings 13, 14, 15 that leads and a contribution in the cosine ^ -out- of the magnetic field probe output, which supplies the current decrease channel of the current feedback loop 31, is supplied to iden- guiding loop 31, is compensated. Current is that of 15 recognize that in the Ausfühmngsbeispiel according to Fig. The magnetic field probe windings 13, 14, 15 subtract the feedback compensation signals from the hed and a contribution to the sine ^ output current feedback outputs before the one Latitude channel dsr current feedback loop 3i provides compensation resulting automatic amplification

A modified embodiment of the cardinalization control circuit 34 can be generated. This is desirable and intercardinal two-period compass error 20 worth seeing because the compensation direct current signal compensation device of the heading transmission, which is fed to the magnetic field probe windings system according to FIG. 4 is in FIG. 5 the we- are shown, essentially with the direction of the from the An essential feature of the exemplary embodiment is related to how inductors measured magnetic field the same way in which the compensation signals are summed up with the and in this respect no relation to the primary signals, & h. at the graduation gain compensation.

gnetfeldsonde 11 instead of at the output of the current return

guide loop 31. In FIG. 5 there are 4 sheets of drawings for the cardinal two

period compass error compensation the sine ψ- ~

and cosine y DC outputs of current feedback loop 31 on lines 32 and 33 are summed together in a summing circuit, shown schematically at 310, before being applied to the input of a variable gain amplifier 188a. The summing circuit 310 according to FIG. 5 corresponds to the summing network 177 to 180 according to FIG. 4, and, as shown schematically, the gain of amplifier 188a can be changed by setting a knob 48a of magnitude γ , which corresponds to the tangent of the desired correction. As in FIG respective cooperating resistors 311 and 312 are applied to summing circuits 320 and 321 instead of going back to the uncompensated sine ψ and cosine ip channels on amplifiers 200 and 201 of FIG. 4 to be added back, the compensation currents in the drawing in FIG. 5 strengths shown are used so that they are fed directly to the windings 13 and 15 of the magnetic field probe 11. The currents are effectively summed up with the magnetic field probe winding outputs, which contribute to the sine ψ and cosine signal outputs of the current feedback loop 31.

The intercardinal or inter-directional two-period compass error compensation signal is shown in The DC sine v signal output of the Current feedback loop 31 is fed to a variable gain amplifier 199a, the gain of which is achieved with the aid of a button 486 is changed according to the size of the required corrections, the amplifier 199a after F i g. 5 corresponds to the variable impedance 199 and the amplifier 200 according to FIG. The outcome of the Amplifier 199a is provided with the aid of two resistors 313 and 314 corresponding to those shown in FIG Ratios modified to the respective summing circuits 320 and 321 and thus the windings 13

Claims (11)

Patent claims: 1. Magnetic compass with a magnetic field detector with a number of inductive windings that respond to the direction and size of the earth’s magnetic field in relation to a vehicle and provide a number of alternating voltage signals that represent the direction and size of the earth’s magnetic field, with an evaluation circuit working with current feedback that is based on the number of AC voltage signals is responsive and provides first and second unipolar signals representative of the direction and magnitude of the earth's magnetic field, with gain control means responsive to the first and second unipolar signals and producing third and fourth unipolar signals representative of the direction of the earth's magnetic field and from the strength of the earth's magnetic field are independent, and having useful means for indicating the direction of the earth's magnetic field, characterized in that the gain control means (34) have first and second, variable conductivity circuits (75 to 77,79 bi s 81) with respective first and second conductivity states, switching devices (83, 84 ) controlled by control devices (87, 92) for simultaneous switching of the first and second separate, variable conductivity circuits (75 to 77, 79 to " 81) of the first to second conductivity state with a controlled duty cycle, and filter means (78, 82) which form part of the first and second variable conductivity circuits (75 to 77, 79 to 81) and which smooth the currents flowing through these circuits, respectively to form the third and fourth unipolar signals that the third and fourth unipolar signals are supplied to separate modulator circuits (45) for modulating the third and fourth unipolar signals with a reference AC voltage signal to form first and second output AC voltage signals indicating the direction of the earth's magnetic field represent that the Steue devices (87, 92) respond to the first and second output AC voltage signals and a comparator (92) for comparing a signal representing the first and second output AC voltage signals with a unipolar reference signal (98) and variable pulse width generator devices (87) include those responsive to the output signal of the comparator (92) and controlled pulse width modulated signals to control the duty cycle of a variable conductance having circuits (75 to 77, 79 to 81) provide that the utility devices exhibit (64) inputs to which the first and second output AC voltage signals are supplied, and that directional error compensation devices are arranged between the evaluation circuit (31) and the inputs of the useful devices (64). 2. Magnetic compass according to claim 1, characterized in that the variable pulse width generator means (87) are controlled by the reference AC voltage signal. 3. Magnetic compass according to claim 2, characterized in that the reference AC voltage signal the excitation signal of the magnetic field detector (l) is 4. Magnetic compass according to one of the preceding claims, characterized in that the Directional error compensation devices 1 ndex error compensation devices included between the gain controllers (34) and the modulator circuits (45). 5. Magnetic compass according to one of the preceding claims, characterized in that the direction error compensation devices
Include bi-period compass error compensators connected between the modulator circuits (45) and the inputs of the utility facilities (64) and the comparator means (92) receiving the first and second output AC voltage signals after passing through the bi-period compass error compensators (48) receive. 6. Magnetic compass according to claim 4 or 5, characterized in that the index error compensation means (37) first time-division operated amplifier circuits (120) which respond cyclically and alternately to the third and fourth signals proportional to sine ψ and cos ψ, an adjustable one , have amplification β representing the Indian error of the vehicle and have cyclic and alternating output signals proportional to /? · Cos y> and /? Deliver · sin ψ at a single output, second amplifier circuits (128,129) which cyclically responsive to afford the cyclic and alternating output signals to separate first and second respective outputs, first summing means (140,141) responsive to the second amplifier circuits (128, 129 ) respond and form a signal proportional to the difference between the signals proportional to sin ψ and β · cos φ , which represents the third signal fed to the modulator circuits (45), and include second summing devices (150, 151) which are fed to the second amplifier circuits ( 128, 129) and form a signal which is proportional to the sum of the signals proportional to cos ψ and β · sin ψ and which represents the fourth signal fed to the modulator circuits (45) 7. Magnetic compass according to claim 6, characterized in that the first time-division operated amplifier circuits (120) include an amplifier with two inputs which are connected along a potentiometer (113) with an adjustable wiper (113a) , that first current switching devices (107) for cyclical forwarding or non-forwarding of the third signal supplied by the gain control device (34) to the grinder (113a) under the control of a reference AC voltage signal, and that second switching devices (109) for cyclical forwarding or non-forwarding of the signal from the gain control devices (34) supplied fourth signal to the grinder (113a) are provided under the control of the reference AC voltage signal after phase shift by 180 °. 8. Magnetic compass according to claim 6, characterized in that the second amplifier circuits (128, 129) have first current switching devices (123) for cyclically forwarding one to the one supplied by the gain control devices (34) 3 4 third signal proportional signal to the second speak and a number of AC voltage signal summers (150, 151) deliver among the controls that determine the direction and magnitude of the earth's magnetism of the reference AC voltage signal and field, with a current return arbe: - second c current switching devices (122) for the cyclical evaluation circuit, which is based on the number of see forwarding of the amplification control 5 AC voltage signals and first and ereinrichtungen (34) supplied fourth signal per second unipolar signals that the direction and supplies portional signal to the first Summiereinrich- size of the earth's magnetic field represent, with reinforcements (140, 141) under the control of the reference controllers that respond to the erite and two ac voltage signals address after phase shift th unipolar signals and third and fourth include by 180 °. io generate unipolar signals that indicate the direction of the earth 9. Magnetic compass according to one of claims 5 represent magnetic field and the strength of the Erdmabis 8, characterized in that the two magnetic fields are independent, and with utility facilities dull compass error compensation devices for displaying the direction of the earth's magnetic field. (48) an amplifier circuit (188) with first and when at high latitudes with magnetic compass second input devices (183, 184), first 15 systems using magnetic field detection summing devices (177, 178) to supply the ren navigated, difficulties arise due to the first and second output AC voltage si- decreasing strength of the horizontal component of the signal to the first input devices (183 ), Earth's magnetic field at high latitudes. A Mazweitc summing device (179, 180) for the supply compass with a magnetic field detector is set up to standardize the first and second output alternating signals in such a way that it only measures the horizontal voltage signals to the second input device component of the earth's magnetic field ), a variable impedance will show at high latitudes the strength of the transmitting devices (186), which are proportionally reduced in parallel to the two-measured components and the th input devices (184) are switched on effective amplification ^ of the comparison, so that a heading information with strengthening circuits (188) proportional to the two results of reduced accuracy
to control period compass errors, so that on it is known (US-PS 35 48 284 and 36 46 537), this Output (189) of the amplifier circuits (188) in the compensation problem of supplying a signal that is essentially independent of the change in interaction with the first and second sums of the field strength of the horizontal component of the measuring device (177, 178, 179, 180), which (- ^ (sin φ + cos φ)) represents, and output signal to the magnetic compass display or third and fourth summing devices (191, 192, evaluation system by including the gain 193, 194) to include the output of the amplifier or the rms values of the impedance amplifier circuits (188) respond and supply corrected data transmission signals in each case in the separate channels of the evaluation system, which are controlled in a relatively complicated manner, but generally in inverse proportion to the relationship to the signal strength, as measured on the magnetic field detector itself sin ψ + y (s \ n ψ + cos φ) became. Although these known systems for many An application, adequate magnetic field compensation and result in 40 sation, compensate the compensation signals le in practice only changes in the horizontal dimensions cos yi + ^ (sin φ + cos ψ) gnetfeldcomponent and they correct in general not also completely the gain changes are and the utility facilities (64) or the counterparts, which are caused by component changes or due to Strengthening control devices (34) are supplied 45 temperature or operating voltage changes or the. caused by component aging. 10. Magnetic compass according to claim 9, characterized in that the properties of the individual indicates that the variable impedance gain control elements of the individual channels of the having devices (186) a first evaluation system without suitable corrective adjustable Include resistance, which is used to change 50 tive settings for correction, eliminating the end of two periods Two period cardinal compass error in the compass transmission error in the automatic Data transmission system is used. Gain control stages are caused. 11. Magnetic compass according to claim 10, characterized in that it has been tried (DE-OS 23 62 975), the disadvantages characterized in that the second variable resistance of these known systems by a relatively complementary element (199) are provided that eliminate the graceful and complex correction circuit of the third summing devices (191, 195). The relatively complicated automatic amplification connect their output and are adjustable, the control stage of this system can, however, be inevitable the two-period intercardinal compass - cause desired two-period compass errors, To correct errors in the data transmission system - It is still known (DE-OS 16 23 555), under ren. 60 Use of two magnetic field detectors to correct the cardinal compass errors in magnetic compass to achieve this through the use of networks, which include coupled double potentiometers, which must be adjusted to one another with high precision. The invention relates to a magnetic compass 65 sen, if they are not supposed to introduce errors themselves,
Furthermore, a magnetic compass system is described in the opening paragraph inductive windings, known on the direction and size mentioned type (DE-OS 19 64 569), in which the of the Erdniagnetfeld compared to a vehicle - Magnetic field detector in connection with a feedback