CN217216876U - Wireless microphone receiver with low-cost adjustable filter circuit - Google Patents

Abstract

The utility model relates to the technical field of wireless microphone receivers, in particular to a wireless microphone receiver with a low-cost adjustable filter circuit, which comprises a receiving antenna, a wireless receiving unit, an audio processing unit, a microprocessor unit and a display unit; the wireless receiving unit is electrically connected with the audio processing unit; the microprocessor unit is respectively and electrically connected with the wireless receiving unit, the audio processing unit and the display unit; the system also comprises an adjustable BPF module; the adjustable BPF module is electrically connected with the receiving antenna; the adjustable BPF module is electrically connected with the wireless receiving unit; the wireless microphone receiver has the advantages of low cost and no debugging of a filter, solves the problem of mutual interference when a plurality of transmitters are used at the same time due to the fact that the IIP3 (input third-order intermodulation intercept point) of the traditional wireless microphone receiver is too low, and does not increase the hardware cost of the receiver.

Description

Wireless microphone receiver with low-cost adjustable filter circuit

Technical Field

The utility model relates to a wireless microphone receiver technical field, concretely relates to wireless microphone receiver with low-cost adjustable filter circuit.

Background

At present, a wireless microphone receiver usually adopts a BPF (band pass filter) with a fixed center frequency to filter out image interference, the BPF has a large bandwidth, and thus, for signals of all transmitters in a receiving channel, because there is no suppression effect in the receiving bandwidth, when a plurality of transmitters are used simultaneously, additional third-order intermodulation suppression cannot be provided, and signals of the plurality of transmitters can generate third-order intermodulation interference at a receiver end, which leads to tone break and shortens the use distance.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a wireless microphone receiver with low-cost tunable filter circuit to prior art's defect and not enough.

The utility model relates to a wireless microphone receiver with low-cost adjustable filter circuit, which comprises a receiving antenna, a wireless receiving unit, an audio processing unit, a microprocessor unit and a display unit; the wireless receiving unit is electrically connected with the audio processing unit; the microprocessor unit is respectively and electrically connected with the wireless receiving unit, the audio processing unit and the display unit;

the system also comprises an adjustable BPF module; the adjustable BPF module is electrically connected with the receiving antenna; the adjustable BPF module is electrically connected with the wireless receiving unit.

Further, the adjustable BPF module is connected with the microprocessor unit.

Further, the adjustable BPF module includes a capacitor C1, and the capacitor C1 is connected in series with the inductor L4, the inductor L5, and the capacitor C2; the other end of the capacitor C1 is connected with a receiving antenna ANT 1; the other end of the capacitor C2 is connected with a BPF _ OUT end;

the capacitor C3, the PCB inductor L1 and the capacitor C4 are respectively connected in parallel on a first lead between the capacitor C1 and the inductor L4; the other ends of the capacitor C3 and the PCB inductor L1 are grounded respectively; the capacitor C9 is connected with the capacitor C4 in series, and the other end of the capacitor C9 is grounded; the resistor R1 and the resistor R4 are connected in series and then connected in parallel on a lead between the capacitor C9 and the capacitor C4; one end of the diode D1 is connected with the resistor R1 in parallel, and the other end of the diode D1 is grounded; the capacitor C12 is connected in parallel between the diode D1 and the resistor R4;

the capacitor C5, the PCB inductor L2 and the capacitor C6 are respectively connected in parallel to a second lead between the inductor L4 and the inductor L5; the other ends of the capacitor C5 and the PCB inductor L2 are grounded respectively; the capacitor C6 is connected with the capacitor C10 in series, and the other end of the capacitor C10 is grounded; the resistor R2 and the resistor R5 are connected in series and then connected in parallel on a lead between the capacitor C6 and the capacitor C10; one end of the diode D2 is connected with the resistor R2 in parallel, and the other end of the diode D2 is grounded; the capacitor C13 is connected in parallel between the diode D2 and the resistor R5;

the capacitor C7, the PCB inductor L3 and the capacitor C8 are respectively connected in parallel on a third wire between the inductor L5 and the capacitor C2; the other ends of the capacitor C7 and the PCB inductor L3 are grounded respectively; the capacitor C8 is connected with the capacitor C11 in series, and the other end of the capacitor C11 is grounded; the resistor R3 and the resistor R6 are connected in series and then connected in parallel on a lead between the capacitor C8 and the capacitor C11; one end of the diode D3 is connected with the resistor R3 in parallel, and the other end of the diode D3 is grounded; the capacitor C14 is connected in parallel between the diode D3 and the resistor R6;

the other end of the resistor R4 is connected with the V _ BPF end through a fourth wire; the other ends of the resistor R5 and the resistor R6 are respectively connected in parallel with the four wires.

After the structure is adopted, the utility model discloses beneficial effect does: a wireless microphone receiver with low-cost adjustable filter circuit, it has low-cost, the advantage of debugging is exempted from to the wave filter, mutual interference problem when solving traditional wireless microphone receiver and using simultaneously because of IIP3 (input third-order intermodulation intercept point) too low many transmitters that cause, and do not increase the receiver hardware cost.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, do not constitute a limitation of the invention, and in which:

FIG. 1 is a topological schematic of the present invention;

fig. 2 is a schematic circuit diagram of an adjustable BPF module according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

As shown in fig. 1, a wireless microphone receiver with a low-cost tunable filter circuit according to this embodiment includes a receiving antenna, a wireless receiving unit, an audio processing unit, a microprocessor unit, and a display unit; the wireless receiving unit is electrically connected with the audio processing unit; the microprocessor unit is respectively and electrically connected with the wireless receiving unit, the audio processing unit and the display unit;

the system also comprises an adjustable BPF module; the adjustable BPF module is electrically connected with a receiving antenna; the adjustable BPF module is electrically connected with the wireless receiving unit.

Further, the adjustable BPF module is connected with the microprocessor unit.

Further, as shown in fig. 2, the tunable BPF module includes a capacitor C1, and the capacitor C1 is connected in series with the inductor L4, the inductor L5, and the capacitor C2; the other end of the capacitor C1 is connected with a receiving antenna ANT 1; the other end of the capacitor C2 is connected with a BPF _ OUT end;

the capacitor C3, the PCB inductor L1 and the capacitor C4 are respectively connected in parallel on a first lead between the capacitor C1 and the inductor L4; the other ends of the capacitor C3 and the PCB inductor L1 are grounded respectively; the capacitor C9 is connected with the capacitor C4 in series, and the other end of the capacitor C9 is grounded; the resistor R1 and the resistor R4 are connected in series and then connected in parallel on a lead between the capacitor C9 and the capacitor C4; one end of the diode D1 is connected with the resistor R1 in parallel, and the other end of the diode D1 is grounded; the capacitor C12 is connected in parallel between the diode D1 and the resistor R4;

the capacitor C5, the PCB inductor L2 and the capacitor C6 are respectively connected in parallel to a second lead between the inductor L4 and the inductor L5; the other ends of the capacitor C5 and the PCB inductor L2 are grounded respectively; the capacitor C6 is connected with the capacitor C10 in series, and the other end of the capacitor C10 is grounded; the resistor R2 and the resistor R5 are connected in series and then connected in parallel on a lead between the capacitor C6 and the capacitor C10; one end of the diode D2 is connected with the resistor R2 in parallel, and the other end of the diode D2 is grounded; the capacitor C13 is connected in parallel between the diode D2 and the resistor R5;

the capacitor C7, the PCB inductor L3 and the capacitor C8 are respectively connected in parallel on a third wire between the inductor L5 and the capacitor C2; the other ends of the capacitor C7 and the PCB inductor L3 are grounded respectively; the capacitor C8 is connected with the capacitor C11 in series, and the other end of the capacitor C11 is grounded; the resistor R3 and the resistor R6 are connected in series and then connected in parallel on a lead between the capacitor C8 and the capacitor C11; one end of the diode D3 is connected with the resistor R3 in parallel, and the other end of the diode D3 is grounded; the capacitor C14 is connected in parallel between the diode D3 and the resistor R6;

the other end of the resistor R4 is connected with the V _ BPF end through a fourth wire; the other ends of the resistor R5 and the resistor R6 are respectively connected in parallel with the four wires.

The utility model discloses a theory of operation as follows:

in the design, the wireless microphone receiver comprises a receiving antenna, an adjustable BPF module, a wireless receiving unit, an audio processing unit, a microprocessor unit and a display unit; the wireless receiving unit is electrically connected with the audio processing unit; the microprocessor unit is electrically connected with the adjustable BPF module, the wireless receiving unit, the audio processing unit and the display unit; the receiving antenna is electrically connected with the adjustable BPF module; the adjustable BPF module is electrically connected with the wireless receiving unit.

The radio receiving unit in this design: the microprocessor sets the receiving frequency of the wireless receiving unit to receive and demodulate the transmitter signal and output the initial audio signal and the pilot signal to the audio processing unit.

The audio processing unit in this design: processing the initial audio signal, such as amplification, low-pass filtering, dynamic range expansion, de-emphasis, and the like, and outputting an audio signal; the pilot signal is decoded, the transmitter's instructions and data are recovered, and the audio signal is output or muted according to the result.

Display unit in this design: the microprocessor controls the display unit to display the RF signal size, AF level, receiving frequency, channel and volume of the receiver. And displaying information such as the battery capacity of the transmitter and the like according to the instructions and the data of the transmitter recovered by the audio processing unit.

The present design differs from conventional wireless microphone receivers in the tunable BPF module. The BPF of the design is a band-pass filter. The input and output of the adjustable BPF are matched to 50 omega in a receiving frequency band, the-3 dB bandwidth of the adjustable BPF is a narrow band (about 1/10 of the receiving frequency band), the center frequency of the adjustable BPF is controlled by direct current voltage, a microcontroller outputs high-frequency PWM voltage, the high-frequency PWM voltage is converted into direct current voltage after passing through a low-pass filter, the direct current voltage is amplified and then output to a V-BPF control end of the BPF, and finally, the voltage is applied to the negative electrode of a variable capacitance diode. The microprocessor changes the PWM voltage duty ratio, namely the V-BPF voltage can be changed, so that the capacitance of the capacitance diode is changed, the BPF center frequency is adjusted, and the microprocessor synchronously controls the BPF center frequency and the wireless receiving frequency to the same frequency in actual work.

The adjustable BPF in the design has the following advantages:

(1) the IIP3 and dry-out resistance of the receiver can be improved.

The IIP3 and the receiving sensitivity of the conventional wireless receiver are generally restricted, and the receiving sensitivity is high, which is relatively lower than IIP3, IIP3 and lower than the receiving sensitivity. Higher receive sensitivity is generally required to achieve longer use distances, and thus IIP3 is generally lower.

The receiver of the design has relatively high IIP3 and relatively strong dry resistance. In actual work, the microprocessor synchronously controls the BPF center frequency and the wireless receiving frequency to the same frequency, and because the adjustable BPF bandwidth is narrow, when a plurality of transmitters are used simultaneously, the corresponding receiver BPF center frequencies are different, so that signals of other transmitters are attenuated to a certain extent (the difference between the current receiver BPF center frequency and the frequencies of other transmitters is different, the attenuation is also different, about-5 dB to-30 dB, the larger the frequency difference is, the larger the attenuation is, and the larger the attenuation is when the frequency difference is the same). If greater out-of-band attenuation is desired, the BPF order may be increased appropriately. The adjustable BPF has a certain attenuation effect on signals of other transmitters, so that the IIP3 of the receiver is increased, the third-order intermodulation interference is reduced, more transmitters can be used simultaneously, and the method can be used for performing, hosting, meeting and other fields needing more transmitters to work simultaneously.

(2) All channels of the receiver can receive the whole frequency band signal of the transmitter, and the frequency allocation is easier.

The existing wireless receiver is different in receiving frequency of different channels, and is segmented because the center frequency and bandwidth of the BPF are fixed, usually a dielectric filter or a sound meter filter, and different channels usually adopt BPFs with different center frequencies, so that the receiving frequency of different channels is different and cannot receive the whole frequency band of a transmitter, and frequency allocation is troublesome.

The center frequency of the BPF of the design can be adjusted, so that all channels can receive the whole frequency band signal of the transmitter, and the frequency distribution is easier. The number of channels available for simultaneous use is greater when the transmitter bandwidth is the same.

(3) The material is easy to purchase and has short period.

The existing BPF usually uses a medium filter or a sound table filter with special frequency, is a relatively cold material, has few suppliers and long purchase period, and the price is also limited by the suppliers. The receiver of the design has the advantages of easy material purchase and short period. Because of adjustable BPF comprises PCB inductance, paster electric capacity (± 0.1pF), paster wire winding inductance (5%), paster resistance, varactor, these are general material, and are more than the hot door, the supplier, and the cost is lower, and the material purchase is easy and the cycle is short.

The adjustable BPF in the wireless receiver of the design has the following characteristics:

(1) the BPF center frequency is adjustable, the microprocessor changes BPF control voltage to adjust the center frequency point, and the control voltage can be generated by PWM filtering, a digital potentiometer, a DAC or other circuits.

(2) BPF need not the debugging, and center frequency is accurate, because of using PCB inductance (inductance value is accurate) and paster electric capacity (± 0.1pF), the component precision is high, can use behind the paster, and production is simple.

(3) The BPF insertion loss is small, because of the use of PCB inductance (high Q) and NP0/C0G patch capacitance (high Q),

(4) BPF uses general material, by PCB inductance, paster electric capacity (± 0.1pF), paster wire winding inductance (5%), chip resistor, varactor constitute, low cost, the material purchase is easy and the cycle is short.

(5) The BPF center frequency tuning range can be changed by changing the parameters (patch parameters and PCB inductance).

(6) The-3 dB bandwidth of the BPF can be changed by changing the parameters (patch parameters and PCB inductance).

(7) The amount of out-of-band attenuation of the BPF can be varied by changing the order of the BPF or changing the parameters (patch parameters and PCB inductance).

(8) The insertion loss in the passband of the BPF can be further reduced by increasing the Q of the PCB inductor (optimizing the PCB inductor can further increase the PCB inductor Q, e.g., the PCB inductor uses wider traces and trace pitches, using a 2OZ copper thick PCB).

The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (3)

1. A wireless microphone receiver with a low-cost tunable filter circuit comprises a receiving antenna, a wireless receiving unit, an audio processing unit, a microprocessor unit and a display unit; the wireless receiving unit is electrically connected with the audio processing unit; the microprocessor unit is respectively and electrically connected with the wireless receiving unit, the audio processing unit and the display unit;

the method is characterized in that: the system also comprises an adjustable BPF module; the adjustable BPF module is electrically connected with the receiving antenna; the adjustable BPF module is electrically connected with the wireless receiving unit.

2. A wireless microphone receiver with a low cost tunable filter circuit as claimed in claim 1, characterized by: the adjustable BPF module is connected with the microprocessor unit.

3. A wireless microphone receiver with a low cost tunable filter circuit as claimed in claim 1, characterized by: the adjustable BPF module comprises a capacitor C1, wherein a capacitor C1 is connected in series with an inductor L4, an inductor L5 and a capacitor C2; the other end of the capacitor C1 is connected with a receiving antenna ANT 1; the other end of the capacitor C2 is connected with a BPF _ OUT end;

the capacitor C3, the PCB inductor L1 and the capacitor C4 are respectively connected in parallel on a first lead between the capacitor C1 and the inductor L4; the other ends of the capacitor C3 and the PCB inductor L1 are grounded respectively; the capacitor C9 is connected with the capacitor C4 in series, and the other end of the capacitor C9 is grounded; the resistor R1 and the resistor R4 are connected in series and then connected in parallel on a lead between the capacitor C9 and the capacitor C4; one end of the diode D1 is connected with the resistor R1 in parallel, and the other end of the diode D1 is grounded; the capacitor C12 is connected in parallel between the diode D1 and the resistor R4;

the capacitor C5, the PCB inductor L2 and the capacitor C6 are respectively connected in parallel to a second lead between the inductor L4 and the inductor L5; the other ends of the capacitor C5 and the PCB inductor L2 are grounded respectively; the capacitor C6 is connected with the capacitor C10 in series, and the other end of the capacitor C10 is grounded; the resistor R2 and the resistor R5 are connected in series and then connected in parallel on a lead between the capacitor C6 and the capacitor C10; one end of the diode D2 is connected with the resistor R2 in parallel, and the other end of the diode D2 is grounded; the capacitor C13 is connected in parallel between the diode D2 and the resistor R5;

the capacitor C7, the PCB inductor L3 and the capacitor C8 are respectively connected in parallel on a third wire between the inductor L5 and the capacitor C2; the other ends of the capacitor C7 and the PCB inductor L3 are grounded respectively; the capacitor C8 is connected with the capacitor C11 in series, and the other end of the capacitor C11 is grounded; the resistor R3 and the resistor R6 are connected in series and then connected in parallel on a lead between the capacitor C8 and the capacitor C11; one end of the diode D3 is connected with the resistor R3 in parallel, and the other end of the diode D3 is grounded; the capacitor C14 is connected in parallel between the diode D3 and the resistor R6;

the other end of the resistor R4 is connected with the V _ BPF end through a fourth wire; the other ends of the resistor R5 and the resistor R6 are respectively connected in parallel with the four wires.

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