JP4833572B2 - Remote control of phantom powered microphones - Google Patents

Description

  The present invention relates to a method for remotely controlling a microphone, which includes at least one microphone capsule and audio amplifier, power supply circuit, processor, control electronics, A / D converter, D / A converter, LED display, etc. At least one auxiliary power receiver selected from the group, and this energy is supplied from a phantom power unit via the cable conductors of the audio cable.

  The power supply of the microphone is conventionally provided by using a power supply source such as a mixer. During phantom power supply, the positive pole of the supply voltage is supplied from two equivalent feeder resistors via the two cable conductors of the audio cable. The current return originates from the third conductor connected to pin 1 of the XLR plug. In order to be able to efficiently use the voltage supplied from the phantom power supply for the power supply of the condenser microphone, the current consumption of the microphone is minimized to prevent an excessively large voltage drop in the feeder resistance. Should be. The maximum current consumption with a 48-V condenser microphone is 10 mA. Phantom power supply is now standardized according to DIN EN 61938 (formerly IEC268).

  In order to generate the polarization voltage of the microphone membrane (usually the value of this voltage is in the region of 20 V dc to 100 V dc), a combinational circuit part or voltage converter is mainly used. The remaining microphone electronics are usually powered by linear regulation, which maintains either the supply feed voltage or the supply current at a predetermined value. This type of power supply is appropriate for a microphone with low power consumption. If the power consumption in the microphone increases, for example if the power consumption increases by using a processor, A / D converter, LED display, etc., linear adjustment becomes a problem. In this case, most of the energy available by phantom power supply is nullified within the linear adjustment factor. However, according to the standard phantom power supply, this limits its current by the feeder resistance, so the maximum supply voltage of the audio amplifier drops sharply due to the linear adjustment of the microphone, reducing the maximum audio output voltage of the microphone. Bring.

  There are other problems with the generation of polarization voltage. This voltage is usually supplied to the microphone membrane via a high ohmic resistance. The power required here is very low. In addition, it is difficult to produce a voltage regulator that efficiently generates a polarization voltage with virtually no power.

  There is another problem related to remote control of the microphone. The use of a microphone increases the need to be able to adjust or change important microphone parameters via remote control. These parameters include polarization voltage on the condenser microphone membrane and associated sensitivity, microphone directivity, phantom power supply type (12V, 24V or 48V), product number, calibration data from the manufacturer, as well as signal Include weakening and connectable filters for audio signals.

  DE 3933870 A1 discloses a method for remote control of microphone parameters such as directivity, step audio filter and pre-attenuation. In this process, the supply voltage transferred to the cable conductor is adjusted via a remote control unit, for example, adjusted in the mixing table in such a way that the amount of supply voltage represents the control information of the microphone. On the microphone side, the supply voltage is released and supplied to the evaluation circuit, thereby generating a control signal as a function of the amount of supply voltage. By this way of data transfer, the control information can be sent to the microphone only in small amounts, so the parameters can also be remotely controlled by the microphone only in small amounts.

  US6028946A (and corresponding EP 0794686A2) discloses a digital microphone. The audio signal is digitized using an analog-to-digital converter and the resulting two-channel digital audio signal is transmitted to the associated amplifier via a symmetric two-wire conductor. Power supply to the microphone is provided from this symmetrical two-wire conductor. By the way, it is implicitly mentioned that in the associated amplifier, the pulses that provide remote control of the microphone settings can be modulated to the voltage of the microphone power supply. It should be noted in this regard that the concept of digital microphone and accompanying digital signal transmission is completely different from an analog microphone, where the analog signal is transmitted from a phantom power line. The additional modulated signal on the line where the digital signal is transmitted at the same time does not cause a problem. This is because the digital audio signal can be easily separated from the additionally modulated signal.

  A problem that has not yet been solved preferably relates to generating a polarization voltage on the condenser microphone membrane. The degree of polarization voltage is directly taken into the degree of sensitivity of the microphone capsule. As a result, the sensitivity of the capacitor capsule can be adjusted using the polarization voltage. This is particularly advantageous with respect to the use of a double membrane capsule part. This is because these capsule parts enable not only sensitivity adjustment but also directivity adjustment when supplying individual films having polarization voltages separately.

  A method of adjusting the polarization voltage using a fixed resistor or a trimmer resistor is well known. In this process, a temporary adjustment of the polarization voltage occurs during assembly of the microphone. The directivity is defined here once with a fixed resistivity. Using this method, in addition to the aging process, it is difficult but possible to only compensate for the immunity in sensitivity caused by assembling the microphone capsule part. For this purpose, polarization voltage reinforcement is necessary during the acoustic measurement of the sensitivity when the microphone is assembled. Also, when the directivity is different, it is not possible to reinforce sensitivity tolerance.

  US4541112A (and corresponding EP0096778B1) discloses an electroacoustic transducer with an adjustable pulse generator that converts DC to AC. A transformer connected to the pulse generator allows the individual power receivers to be inductively separated. The supply loop is inductively connected to the alternating current generated from the pulse generator using separate windings on the transformer. This document is hereby incorporated by reference.

  In conjunction with microphone power supply, the power available through phantom power supply is optimally used and required to receive individual outputs such as audio amplifiers, microphone capsules, processors, controllers, A / D converters, LED displays, etc. A solution is needed when it is converted to an operational voltage.

  An object of the present invention is to provide a method capable of maximizing the use of electric power that can be used by phantom power supply for supplying an audio amplifier.

  These objects are achieved by a microphone with a power supply circuit for each power receiver, which is connected to the control unit, which converts the direct current transmitted to the alternating current through the cable conductor of the audio cable. And a supply loop to each of the power receivers, wherein the supply loop is inductively coupled to the alternating current generated from the controller using a separate winding of the transformer, The supply loops are also inductively coupled.

  In this process, all the voltages required for the power receiver are generated from a power supply circuit, for example, a DC / DC converter, which has the following properties. This power supply circuit is adjusted or operated in such a way that the power is adapted to the phantom power supply unit. Thus, the maximum possible power that the phantom power unit unit makes available can always be consumed by the microphone power circuit. The main current consumption of the power supply circuit is constant. The power supply circuit thus acts like a constant current sink for the phantom power supply. Separate supply loops for separate power receivers are separated in the power supply circuit using transformers, and different demands of separate power receivers (ie large voltage and small current on polarization voltage, medium to audio amplifier) In addition to low voltage and medium current consumption, the requirement to provide low voltage and high current to the digital electronics with as little power loss as possible.

  The effective effect of the condenser microphone according to the present invention is clear. That is, the power available by the phantom power unit is optimally used using the concept of power supply provided. As a result, the microphone may have new functions (eg, remote control, new operational concepts, auto-reinforcement possibilities, etc.), while the microphone's maximum audio output voltage remains the same. The generation of an essentially power-free polarization voltage actually occurs as a by-product of a simple additional winding on the transformer.

  As a result of using the highest possible ohmic level, there is another advantage that the switch ripple of the power supply circuit or DC / DC converter can be eliminated very easily with a constant power supply at the input of the power supply circuit.

  Possibility of adapting the microphone, for example, changing the polarization voltage to change the sensitivity, continuously changing the directivity of the double membrane capsule part, and controlling the microprocessor to store the measurement data In addition to changing the signal, remote control of data at a substantially faster rate as the likelihood of adaptation, such as modifying the frequency range, maximum audio output voltage, amplification, or THD of the audio amplifier, increases There is a need to transfer to the microphone via.

  In accordance with the present invention, these objects are achieved by a method for remotely controlling a microphone. This is because the frequency modulation voltage is supplied as a control signal to at least one of the two cable conductors, and phantom power supply also occurs via this conductor, and the frequency modulation voltage on the microphone side is controlled by the control electronics, For example, it is supplied to a microcontroller or CPLD (Complex Programmable Logic Device) and sends a command to an individual power receiver according to a frequency modulation control signal.

  In this method, the frequency modulation voltage is above the supply voltage of the phantom power supply. Data transfer occurs, for example, from a transmitter arranged in a mixing table or a device in front of the mixing table to a microphone via a voice line. The carrier frequency for FSK modulation is now higher than the audio frequency range to be transmitted by the microphone.

  By using frequency modulated signal transmission, a substantially faster data rate can be obtained as opposed to transmitting with direct current. As a result, a number of parameters can be transmitted using a certain protocol. The modulation carrier frequency is preferably approximately 100 kHz and can be separated from the audio signal using a filter.

  To meet the need for low immunity within the condenser microphone's polarization voltage (eg, ± 0.5 dB immunity is required for sensitivity), the polarization voltage is flexible even when the microphone is assembled. A solution is needed that allows for easy adjustment.

  In accordance with the present invention, this is accomplished by a condenser microphone that has at least one circuit that regulates the polarization voltage (the circuit that regulates the polarization voltage comprises an analog regulation loop that is fed with an unregulated voltage). And a digital regulation loop, the digital regulation loop comprising control electronics, such as a microcontroller or CPLD, that provide the analog regulation loop with a desired value of polarization voltage calculated using a correction factor, And for the purpose of feedback, the output of the analog regulation loop is connected to the control electronics.

  In this process, the polarization voltage is adjusted by a voltage regulation loop integrated into the microphone. The desired value of the polarization voltage is preset in this circuit by the control electronics via a D / A converter. As a result, an adjustment that evaluates the polarization voltage in detail can be performed. The desired value of the polarization voltage can also be transmitted to the control electronics by remote control. The obtained polarization voltage tolerance is determined by the tolerance and temperature characteristics of the reference voltage source.

  Adjusting the polarization voltage through the microphone's digitally controlled adjustment loop allows for very accurate, robust to interference and remotely controllable adjustments to the condenser microphone's voltage divider electrodes Become. As a result, it is possible to reach very limited demands on sensitivity and directivity during manufacturing of the capacitor microprocessor and during measurement of the measurement technology. Adjustment with remotely controllable polarization voltage has the advantage that readjustment with a fixed or trimmer resistor is no longer necessary, and this fact has a positive effect on cost. Compared with existing solutions using a fixed set of polarization voltages, the following additional possibilities arise in the context of a condenser microphone according to the invention.

  As a function of the individual performance of the double membrane capsule part, when adjusting the directivity separately, the sensitivity of different microphones can be reinforced and the required correction factors needed to reinforce the polarization voltage can be stored. .

  In combination with remote control, as described above, for example, the polarization voltage can be measured during acoustic measurement with a closed microphone, and the correction factor can be stored again.

  It is particularly advantageous to have the possibility to change the polarization voltage of the remotely controllable microphone and thus to change the directional effect during operation. For example, a microphone can acoustically follow an actor moving during an opera performance, for example.

  The condenser microphone according to the invention allows the microphone sensitivity to be re-measured due to aging without disassembling the microphone, which also means a cost saving for the user. Thus, while replacing the microphone capsule, the original sensitivity of the microphone can be readjusted by remote control later, ie after capture.

  Preferably, the carrier frequency of the control signal is approximately 100 kHz. Also, the audio signal is transmitted through the cable conductor, and the frequency modulation voltage is supplied to the cable conductor.

  Preferably, the frequency modulation voltage is supplied to the cable conductor and the cable conductor as a common mode signal to the same extent. The frequency modulation voltage is separated from the audio signal by the input differential amplifier. Alternatively, the frequency modulation voltage is separated from the audio signal by a low pass filter.

Further, preferably, in response to a control signal from the remote control unit to the microphone, a data recognition message is transmitted to the remote control unit. Here, the data recognition message is also a frequency modulation signal.
(wrap up)
The present invention relates to a method for remotely controlling a microphone, the microphone comprising at least one microphone capsule part (9), an audio amplifier (10), a power supply circuit (11), a processor, control electronics (39), A / At least one auxiliary power receiver selected from the group of D converter (44), D / A converter (46), LED display (25), etc., and this energy is the cable conductor of the audio cable The phantom power unit (31) is supplied from the so-called phantom power supply via (1, 2).

  In the present invention, a frequency modulation voltage is supplied as a control signal to at least one of the two cable conductors (1, 2), and phantom power supply also occurs via this conductor, and the frequency modulation on the microphone side The voltage is supplied to control electronics (39), for example a microcontroller or CPLD, which sends commands to the individual power receivers according to the frequency modulation control signal.

  Hereinafter, the present invention will be further described with reference to the drawings.

  FIG. 1 is a block diagram showing main components of a microphone according to the present invention. The phantom power supply (shown in FIG. 5) of this microphone is comparable to the phantom power supply unit 31 placed behind a plug 4 (eg, XLR plug) having three poles in or in front of the mixing table. The feeder resistances 32 and 33 are executed. Such a phantom power supply is shown in FIG. According to the standard, three phantom power supplies are possible, i.e. the associated value of the feeder resistance supplying 12V, 24V or 48V is 680Ω, 1.2 kΩ or 6.8 kΩ, respectively. Here, line 1 and line 2 represent cable conductors supplied from the phantom power supply unit, and line 3 represents a ground line normally connected to the ground cable shield. The phantom power supply unit 31 is connected to the input of the power supply circuit 11 according to the present invention via an audio cable, that is, via the line 1, the line 2, and the resistors 5 and 6. Capacitance 7 smoothes the supply voltage to ground. Resistors 5 and 6 are feeder resistances of the microphone. These resistors are used to isolate the microphone power supply from the output of the audio amplifier 10. Microphone feeder resistances 5 and 6 are assigned as additional internal resistances for the phantom power supply 31. A power match exists when the internal resistance of the phantom power unit matches the internal resistance of the microphone power circuit 11. Therefore, in the case of power adaptation, half of the phantom power supply voltage is the supply voltage to the power supply circuit 11. This power is the maximum value that can be generated from the phantom power unit 31, but here it is distributed via the power circuit 11 in the form of a DC / DC converter to all energy consuming parts of the microphone. The overpower is generated here to be available to the audio amplifier 10 so that the maximum sound output voltage of the microphone is as high as possible. For different power supply voltages (in accordance with standards 12V, 24V, or 48V), the circuit can be designed in such a way that power adaptation for different phantom power supplies occurs automatically. This work is then performed by the control unit 12 described below.

  The power supply circuit 11 includes a power supply 13, a control unit 12, and a transformer 14 connected to the control unit 12. The control unit 12 having the transformer 14 forms a circuit unit, where the DC voltage is converted into an AC voltage. In this case, the transformer is part of the circuit that generates the oscillation. Naturally, alternating current can also be generated by the controller 12 independently of the transformer. The control unit 12 therefore consists of an oscillating circulation independent of the transformer, which generates an alternating current. The transformer only provides the function of converting alternating current to a separate output voltage.

  In a preferred embodiment, the AC signal has a frequency in the range of 100 kHz to 130 kHz. The AC signal can also oscillate freely. This thus represents the possibility of the simplest embodiment for such a circuit. The only important factor is that the frequency range of the AC signal must be outside the audible frequency range in order not to produce interference with the audio signal that cannot be removed by simple filtering. On the other hand, this frequency must also be too high, otherwise the efficiency of the circuit is reduced and transmission interference can be expected.

  Another advantage of using a frequency of 100 kHz to 130 kHz is that this frequency can also be used as a circulating pulse to the control electronics 39 provided in the microphone. As a result, interference signals generated by digital techniques are minimized. This is because no other mixed product is generated between the digital cycle time and the oscillation frequency of the DC / DC converter.

  The generated AC signal is supplied to the transformer 14. As a result of the separate windings on the transformer, separate current loops 15, 16, and 17 are generated to be supplied to the individual energy consuming parts. This separation makes it possible to supply power to a low-voltage consumer at the same time with a high current consumption, in addition to a consumer requiring a high voltage but a low current, with as little power loss as possible. The diodes 18, 19, 20 and capacitors 21, 22, and 23 of the individual supply loops 15, 16, and 17 represent rectifier circuits that convert AC voltage to DC voltage. Naturally, from this technical field, more complex and more efficient rectifier circuits can be provided for the individual supply loops. The supply loop 16 serves to provide a polarization voltage to the microphone capsule 9, which is supplied to the microphone capsule part 9 via a resistor 8.

  The invention is of course not limited to condenser microphones, since any kind of microphone, in particular a dynamic microphone, can be connected to the phantom power supply. The individual power receivers are supplied by phantom power as in the method shown in FIGS. However, in the case of a dynamic microphone, the supply loop 16 is not necessary because no polarization voltage is required.

By using the constant current source 13 at the input of the DC / DC converter, a constant primary current intake is guaranteed. The constant current source 13 acts like a constant current sink with respect to the phantom power unit 31 and represents a constant current source to the power circuit 11. The constant current source 13 with the highest possible ohmic level simplifies, among other effects, the filtering of switching ripples generated during DC / AC conversion, which at the same time is an overlay of interference on the audio signal. This type of electrical component is very well known to those skilled in the art. A circuit example of a constant current source from this technical field is shown in FIGS. FIG. 3 shows a “transistor LED” constant current source with bipolar transistors. With this current source, the LED operates in the flow direction. Consequently, at the same time that a constant voltage is supplied to the LED, such a voltage is also supplied to the series connection of the basic emitter diodes of the transistor having the emitter resistance. The current delivered by this current source is therefore I = (U _LED −U _bc ) / Re, where U _LED is the voltage drop across the LED, U _bc is the basic emitter voltage, and Re is the emitter resistance.

The circuit of FIG. 4 includes a constant current source having two counter-connected degenerative transistors 28, 29, and has an additional integrated constant current source 30. This circuit is preferred because of its better performance in terms of constant current and higher starting resistance. The current source 30 generates a voltage drop at the reserve resistance Rc equal to the voltage drop _URc at the emitter resistance Re of the transistor 28. Here, the current of the constant current source is I = U _Rc / Re. Transistor 29 here together with transistor 28 forms a counter-countered system that ensures a comparable voltage drop across resistors Rc and Re. As a result, the current I of the current source is also kept constant. Therefore, the current of the current source 30 is smaller than the constant current finally flowing through the DC / DC converter 11 by a factor of 100.

  Naturally, other types of constant current sources, for example, current sources having inverting operational amplifiers, Howland current sources, etc. may be provided.

  The supply voltage generated by the power supply circuit 11 to the audio amplifier 10 is not adjusted in the preferred embodiment. In the supply loop 16 of the microphone capsule 9, adjustment circuits 47 and 48 are provided between the diode 18 and the resistor 8, which comprises a digital adjustment loop 47 and an analog adjustment loop 48 and is supplied to the microphone capsule 9. Provided for the polarization voltage. FIG. 6 along with FIG. 7 shows such preferably remotely controllable adjustment circuits 47 and 48. The control signal required to adjust the polarization voltage can be transmitted via at least one of the two cable conductors 1 and 2. The detailed structure and manner in which such adjustment circuits 47 and 48 operate will be described further below. If current and voltage limits are not already defined in the digital circuit part, the rest of the supply loop can also be provided with a regulation circuit. In the preferred embodiment of FIGS. 1 and 2, no adjustment circuit is provided in the supply loop 15 to the audio amplifier 10. As a result, the entire power (the processor, the control electronics 39, the polarization voltage in the microphone capsule 9, the power not used for other circuit parts such as the A / D converter 44, the D / A converter 46, and the LED display 25) is audio. The amplifier 10 can be used. As a result, a high maximum audio output voltage can be achieved with a current saving design of the audio amplifier 10 to achieve a high maximum audio output voltage. In principle, the resulting supply voltage of the audio amplifier 10 can also exceed the voltage made available by the phantom power supply. It is also possible to generate a very simple positive and negative supply voltage in the audio amplifier 10 from the method of operation of the power supply circuit 11. As a result, the audio amplifier 10 can also use ground as a natural potential. The supply voltage of the audio amplifier (10) can therefore be symmetrical with respect to ground.

In a more advantageous embodiment, said type of DC / DC converter 11 operates with an efficiency of approximately 82%. Even in the most advantageous case, power is lost in the DC / DC converter, so it is advantageous to connect the consumer in series with the DC / DC converter if possible. As a result of using the constant current source 13, by connecting the consumer to a constant current consumption, eg, a logic supply 24, a fixed direct current, eg, control electronics 39, or LED display 25, A / D converter 44, Alternatively, it can be easily made available for series connection to the DC / DC converter 11 for the D / A converter 46 and the like.

  A corresponding embodiment of the power supply circuit 11 is shown in FIG. Compared to FIG. 1, the difference is that only the polarization voltage and the voltage for the audio amplifier 10 are generated from the DC / DC converter. Other consumables are connected in series with the DC / DC converter, such as, for example, a logic supply 24 that enables a fixed predetermined direct current to the control electronics 39 or LED display 25. The digitally connected series-connected DC / DC converter 11 operates as an active load resistor, and the energy used in this resistor is not converted to heat, but for the most part the audio amplifier 10 of the microphone capsule 9 and the polarization. Converted to usable supply power with voltage.

  As shown in FIG. 2, a Zener diode 27 is provided in conjunction with a logic supply 24 that makes available a reference voltage and additional digital electrons, which Zener diode is particularly suitable for stabilizing the voltage. Any current sent by the constant current source 13 without being consumed via this diode 27 is discharged to ground. In principle, instead of the Zener diode 27, another constant current source or a shunt regulator can be used.

  The discharged power is a product of the current of the constant current source 13 and the voltage supplied to the power supply circuit 11. In the block diagram of FIG. 1, all voltages are supplied to the DC / DC converter 11 and all voltages are generated from the DC / DC converter. In the block diagram of FIG. 2, the voltage is divided into a portion that supplies to the DC / DC converter 11 and a second portion that supplies the LED 25 and digital supply. The DC / DC converter represents an active reserve resistance to the LED 25 or digital supply. Although the current consumption of the digital supply is not constant, the current I remains constant by the current source 13, so that the overcurrent that exists must be removed via the Zener diode 27, depending on the operating status of the digital electronics. For the supply of the audio amplifier 10, power P = voltage available in I × DC / DC converter × efficiency of DC / DC converter can be used. For LED and digital electronics, power P = I × voltage on digital electronics and LEDs is available.

  An example is given to illustrate. The current consumption of the audio amplifier 10 is approximately 0.8 mA in an uncontrolled state, and the current consumption of the digital electronics is approximately 4.2 mA. The current source 13 sends a constant current of approximately 4.7 mA. Therefore, in this special case, it is more advantageous to use a series connection to a DC / DC converter, rather than via a DC / DC converter, to pass voltage for digital electrons. Furthermore, in another development, with respect to energy, it is more advantageous to pass all required voltages through a DC / DC converter, as in the solution shown in the block diagram of FIG.

  Converting the supply voltage to the audio amplifier 10 in this case results in the maximum power available to the amplifier, ie P = 4.7 mA × 18 V × 0.82 = 69 mW. The voltage at the audio amplifier 10 is thus U = P / I = 69 mW / 0.8 mA = 55V. This voltage is much higher than the 24V voltage sent by the phantom power supply 31 during power adaptation. However, since the polarization voltage is also generated on the membrane of the capsule part 9, the actual supply voltage value of the audio amplifier 10 is slightly lower than this value, but can still be used without a DC / DC converter. Much higher than 24V.

  The figure shows a microphone 54 which is connected to a transmitter or remote control unit 55. The remote control of the important microphone parameters here takes place directly via the audio cable, ie line 1, line 2. The control unit 55 is preferably on the mixer or arranged in front of the mixer. A microcontroller 35 having a parameter control input 34 controls the frequency modulation device 36 and applies the frequency modulation signal to the two cable conductors 1 and 2 of the audio cable to the same degree. The frequency modulated signal can then be suppressed as a common mode signal for the input differential amplifier 42. At the same time, the supply voltage of the phantom power unit 31 is supplied to the two cable conductors 1 and 2 via the feeder resistors 32 and 33. In a preferred embodiment, the frequency modulation signal is supplied to only one of the conductors of the audio cable, i.e. only to the conductor 2 not intended for the audio signal.

  In a preferred embodiment, the frequency modulated signal is generated by FSK (frequency shift keying) or CPFSK (continuous phase FSK). Both modulations are well known from digital data transfer technology. In principle, it is also possible to use ASK (amplitude shift keying) or PSK (phase shift keying) modulation. However, ASK is more susceptible to interference and PSK modulation is more difficult to perform from a circuit technology perspective. In contrast to the well-known application of the method, an important factor when used in microphones is that the modulation signal must be separated from the analog signal, ie the audio signal. Even when the frequency modulated signal is applied only to the conductor 2 that is not intended for the audio signal, electrostatic coupling between the two conductors 1 and 2 of the audio cable causes interference in the audio signal. This electrostatic coupling is determined by the structure and length of the audio cable. Therefore, filtering the interference is difficult even with the fact that the control signal is known.

  In the microphone, the frequency modulation voltage is separated from the audio signal using a filter 37 (eg, a bandpass filter), and the control information contained therein is controlled by a control electronics 39 (eg, a microcontroller or CPLD (coupled programmable). Logic circuit)). The cable conductor 2 is separated from the ground via a capacitance 43. The control electronics 39 is connected in front of a comparator 38 that functions as a voltage comparator. Commands from the output of the control electronic circuit 39 are, for example, the power supply circuit 11 (shown in FIGS. 1 and 2), the audio amplifier 10, the processor, the control electronic circuit 39, the A / D converter 44, and the D / A conversion. It reaches the vessel 46 etc.

  The frequency modulation of the two voice lines 1 and 2 is performed in the remote control unit 55, which is preferably located close to the mixing table. In the remote control unit 55, on the one hand, the carrier frequency must be applied in the direction towards the microphone 54, and on the other hand, all modulation frequencies must be suppressed in the direction of the mixing table. Only the audio signal coming from the microphone 54 has to be transmitted. In order to make the modulation frequency suppression simpler, the modulation is carried out at both the voice lines 1 and 2 at the same level. In the remote control unit 55, as a result, the frequency modulation signal appears as a common mode signal to the input differential amplifier 42 and it can be appropriately suppressed as a common mode signal. In a second variant of remote control, frequency modulation occurs only on the line that does not pass the audio signal, ie line 2. In the direction towards the mixing table, with this type of remote control, the frequency modulation signal can be removed by filtering through the low-pass filter 41. The phantom power supply unit 31 includes a differential amplifier 42 and a low-pass filter in addition to the feeder resistors 32 and 33. However, as shown in FIG. 5, the phantom power supply unit 31 does not have to be integrated into the remote control unit. For example, they can also be provided on a mixing table.

  During transmission of the control signal from the remote control unit 55 to the microphone 54, in order to ensure that the control signal has actually reached the control electronics 39, the control electronics 39 receives the control signal and receives a data recognition message. Is transmitted to the remote control unit 55. The data recognition message can also be a frequency modulated signal. Data recognition messages for remote control functions are not absolutely necessary. However, it increases the reliability of the system at the cost of adding electronic circuitry.

  Of course, the method of remote control is not limited to condenser microphones. This is because any kind of analog microphone, in particular a dynamic microphone, can be operated as a means of phantom power supply.

  The microphone according to the present invention can be connected to a standard phantom power supply without affecting the functionality of the microphone. If the phantom power supply is equipped with a remote control device, the microphone can be remotely controlled. Otherwise, the microphone can be actuated by a switch attached directly to the microphone.

  FIG. 6 shows a condenser microphone according to the invention, where the adjustment of the polarization voltage occurs as a means of a two-step control adjustment loop. Here, the second digital adjustment loop 47 overlaps the internal analog adjustment loop 48. As a result, it becomes possible to generate the polarization voltage of the microphone capsule 9 that is sufficiently adjusted and free of interference.

  A preferred frequency modulation signal having control information is transmitted via a cable conductor and is further connected to the phantom power unit 31 and reaches the control electronics 39 via a filter 37 and a comparator 38. A detailed description of remote control of a microphone according to the present invention has already been given above. See also in particular FIG. Control of the control electronics 39 can also occur via adjusting the device of the microphone itself or actuating the elements. The control electronics can also be connected to a wireless or infrared interface or to a lead interface for wireless transmission purposes. The desired value obtained in the control signal due to the polarization voltage is sent to the analog adjustment loop 48 via the D / A converter 46 by the control electronics 39. A pulse width modulation circuit (PWM) can be used instead of the D / A converter. Although PWM circuits have lower conversion speeds, they are cheap and are therefore very suitable for adjusting a certain level for these converters. FIG. 7 is an example embodiment, where control electronics 39 (eg, microcontroller, CPLD, D / A converter, or PWM 46) operates in an analog regulation loop 48. Many analog adjustment loops are well known in the art to those skilled in the art knowing the present invention, and it is easy to select dimensions for such adjustment loops. In the schematic diagram shown in FIG. 6, the analog adjustment loop 48 includes an adjustment circuit 56 and voltage dividers 49 and 50. Details of the adjustment circuit 56 and the analog adjustment loop 48 are shown in FIG.

  The analog regulation loop 48 is preferably supplied by the power supply circuit 11 having an unregulated voltage of approximately 100V to 120V. The DC / DC converter may be of the same type as the converter described above or the converter shown in FIGS. Resistors 5 and 6 are feeder resistances of the microphone. These are used to isolate the microphone power supply from the output of the audio amplifier 10. The sizes of the resistors 5 and 6 are equal to maintain the symmetry between the line 1 and the line 2.

  The present invention is of course not limited to condenser microphones supplied with phantom power. Energizing the individual power receivers of the condenser microphone can also be performed, for example, by a battery in the microphone.

  The desired value provided from the D / A converter, the PWM 46, or more precisely, the polarization voltage correction value, is compared with the actual value via the operational amplifier 52. The desired value is calculated from measurement data measured during the manufacture of the microphone and programmed into the control electronics. As the reference value for this calculation, either the exact reference voltage 45 of the conductor or the reference voltage programmed during the print measurement in the control electronics is used. The reference value 45 may be made available by the logic supply 24, for example. Such a logic supply 24 is preferably powered by the DC / DC converter 11 and is not shown in FIG. 7, but is shown in FIGS.

  In order to discourage the undesired effects of high frequency interference on the analog regulation loop 48, the preferred embodiment is between a D / A converter or PWM 46 and the input of the analog regulation loop 48, as shown in FIG. A low-pass filter 51 is provided. The actual value generated from the analog adjustment loop 48 is obtained from the voltage divider 49 and the voltage divider 50 and supplied to the inverting input of the operational amplifier 52 via the impedance converter 53. The feedback line and the impedance converter are not included in the schematic diagram of FIG. At the same time, this voltage is also supplied to the input of the A / C converter 44 of the digital regulation loop 47. The resulting digital signal is made available to the control electronics 39 as feedback. As a result, the outer digital adjustment loop 47 is closed. In FIG. 7, the voltage divider from which the actual value is obtained is represented by a resistor 49 and a resistor 50. As shown in FIG. 7, in addition to the A / D converter 44 and the control electronics 39, the D / A converter 46 can also be integrated into a single component.

  As an output of the analog adjustment loop 48, the adjusted polarization voltage supplied to the microphone capsule 9 through the high ohmic resistor 8 is obtained. The correction voltage required to calculate the adjusted polarization voltage without interference, or the corresponding correction factor, may correspond to different settings that reflect certain sensitivities, guide characteristics, and aging parameters. These can then be stored in a memory in the control electronics 39 and can be recalled at any time.

  These correction factors can later be changed by remote control in a closed microphone, for example in the after-service department, or by an agent or even a user. In addition to the possibility of correcting microphone performance by aging and replacing the microphone capsule, on-site custom limited microphone tuning is also possible.

  The invention is not limited to the examples of the individual embodiments. Naturally, it is also conceivable to use a microphone in which all or at least some of the circuits are mixed. For example, remote control of all remotely controllable components can be provided in the microphone, and the power supply circuit 11 can provide a power receiver for all possible microphones.

1 is a block diagram of a condenser microphone according to the present invention having a power circuit. FIG. 1 is a block diagram of an embodiment of a condenser microphone according to the present invention having a power circuit. FIG. FIG. 3 is a circuit diagram of a constant power supply of a transistor LED according to the technical field of the present invention. FIG. 3 is a circuit diagram of a constant power supply having a counter-connected transistor according to the technical field of the present invention. It is a block diagram of the capacitor | condenser microphone connected to a remote control part. 1 is a block diagram of a condenser microphone having an integrated circuit that adjusts a polarization voltage. FIG. It is a circuit diagram which adjusts a polarization voltage provided with an analog adjustment loop and a digital adjustment loop.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cable conductor 2 Cable conductor 3 Ground wire 4 Plug 5, 6 Resistance 7 Capacitance 8 Resistance 9 Microphone capsule 10 Audio amplifier 11 Power supply circuit 12 Control part 13 Current source 14 Transformer 15, 16, 17 Current loop 18, 19, 20 Diode 21, 22, 23 Capacitor 24 Logic supply 25 LED display 27 Zener diode 28, 29 Transistor 30 Current source 31 Phantom power supply unit 32, 33 Feeder resistance 34 Parameter control input 35 Microcontroller 36 Frequency modulator 37 Filter 38 Comparator 39 Control electronics 41 Low-pass filter 42 Input differential amplifier 43 Capacitance 44 A / D converter 45 Reference voltage 46 D / A converter 47 Digital adjustment loop 48 Analog adjustment loop 49, 50 Voltage divider 51 Low-pass filter 52 Operational amplifier 53 Impedance conversion 54 Microphone 55 Remote control unit 56 Adjustment circuit

Claims (8)

A method of remotely controlling a microphone (54) that receives an audio signal, comprising:
The microphone (54) includes an audio amplifier (10) and a power supply circuit (11), the power supply circuit (11) includes a constant current source (13), and the microphone includes a first cable conductor (1). ) And a second cable lead (2) connected by an audio cable to the remote control unit (55), the remote control unit (55) comprising a frequency modulator (36), a microcontroller (35), A parameter control input (34) and a phantom power unit (31);
The method
By controlling the frequency modulation device (36) by the microcontroller (35) connected to the parameter control input (34), the frequency modulation device (36) transmits the frequency modulation signal to the first cable. a step so as to supply on lead (1) and / or the second cable conductor (2),
Applying a supply voltage from the phantom power unit (31) to the first cable conductor (1) and the second cable conductor (2) ;
The constant current source (13) receiving the supply voltage from the first cable conductor (1) and the second cable conductor (2);
The constant current source (13) outputting a constant current signal;
The power supply circuit (11) generates a plurality of voltages by using the constant current signal, and one voltage of the plurality of voltages is an unregulated voltage, and the audio amplifier (10 ) Received by ,
The microphone (54) acquires the control information included in the frequency modulation signal by separating the frequency modulation signal and the supply voltage by the filter (37), and the control electronic device (39) A method for evaluating control information.   The method according to claim 1, characterized in that the carrier frequency of the frequency modulation signal is approximately 100 kHz. The audio signal is transmitted via the first cable conductor (1) and the frequency modulation signal is supplied to the second cable conductor (2). Item 3. The method according to Item 2. The frequency modulation signal is applied to the first cable conductor (1) and the second cable conductor (2) at the same level as a common mode signal. 2. The method according to 2. It said remote control unit (55) further comprises an input differential amplifier (42), said frequency modulation signal, characterized in that it is separated from the audio signal by the input differential amplifier (42), according to claim 4. The method according to 4. Said remote control unit (55) further includes a low-pass filter (41), said frequency modulation signal, characterized in that it is separated from the audio signal by the low-pass filter (41), according to claim The method according to any one of claims 1 to 5. In response from said remote control unit (55) to the frequency-modulated signal of the to the microphone (54), data recognition message, characterized in that it is transmitted to the remote control unit, one of claims 1 to 6 The method of crab.   The method of remote control according to claim 7, wherein the data recognition message is also a frequency modulated signal.

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