JP2020202521A - Radio receiving device and luminaire including the same - Google Patents

Abstract

To provide a radio receiving device of the super-heterodyne system capable of suppressing deterioration of reception performance due to noises, and a luminaire using the same.SOLUTION: The radio receiving device 100 includes: a mixer 16; a local oscillator 18 that outputs a local oscillation signal having local oscillation frequency to the mixer 16; and an RSSI 24 that detects the strength of intermediate signal having intermediate frequency output from the mixer 16. The radio receiving device 100 is configured so as to, when the strength of the intermediate signal detected by RSSI24 exceeds the specified reference value, change the local oscillation frequency of the local oscillation signal output from the local oscillator 18.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a wireless receiver and a lighting device including the wireless receiver.

A superheterodyne wireless receiver using a local oscillator whose frequency is variable according to the receiving channel is widely used (Patent Document 1). In the super heterodyne type wireless receiving device, the frequency of the high frequency received signal is converted into an intermediate frequency by using the local oscillation signal generated by the local oscillator, and the received signal is demolished. For example, the difference between the local oscillation frequency generated from the local oscillator and the radio frequency of the target wave is zero or very low, and is often set to several tens of kHz to 100 kHz.

Japanese Unexamined Patent Publication No. 2011-250122

By the way, when the intermediate frequency is low, noise from a switching circuit represented by a power supply circuit or the like may be superimposed on an intermediate frequency circuit constituting a wireless receiver arranged in close proximity to each other. When noise having a frequency corresponding to the pass band of the bandpass filter constituting the intermediate frequency circuit is superimposed, the noise is input to the demodulation circuit as it is. Then, when a signal of the radio frequency originally used is input to the noise at the same time, the noise is superimposed on the signal obtained by demodulation, which leads to deterioration of the reception performance in the wireless receiving device.

In addition, in order to prevent deterioration of reception performance due to noise, a clock shift circuit that shifts the clock frequency when the clock frequency used inside the circuit or its higher-order components becomes the same as the radio frequency used is used. May be done. However, when it is difficult to specify the frequency of noise, the clock shift circuit cannot suppress the deterioration of reception performance due to noise.

One aspect of the present disclosure is a superheterodyne type wireless receiver, which is a mixer circuit, a local oscillation circuit that outputs a local oscillation signal having a local oscillation frequency to the mixer circuit, and an output from the mixer circuit. A strength detection circuit for detecting the strength of an intermediate signal having an intermediate frequency is provided, and when the strength of the intermediate signal detected by the strength detection circuit exceeds a predetermined reference value, it is output from the local oscillation circuit. It is a wireless receiving device characterized in that the local oscillation frequency of the local oscillation signal is changed.

Here, the local oscillation circuit includes a voltage control transmitter that constitutes a phase lock loop circuit, and the voltage control is performed when the strength of the intermediate signal detected by the strength detection circuit becomes equal to or higher than a predetermined reference value. The local oscillation frequency of the local oscillation signal output from the local oscillation circuit may be changed by changing at least one of the inductor and the capacitor that determine the oscillation frequency of the transmitter.

Further, a switch for blocking the high-frequency input signal to the mixer circuit is provided, and the switch is used to block the high-frequency input signal to the mixer circuit when the intensity of the intermediate signal is detected in the intensity detection circuit. It may be configured.

Another aspect of the present disclosure is a lighting device including the wireless receiving device, which is output from the mixer circuit when the dimming level is equal to or higher than a predetermined reference dimming level in response to a change in the PWM signal for setting the dimming level. The lighting device is characterized in that the intermediate frequency of the intermediate signal is changed.

According to the present disclosure, it is possible to provide a superheterodyne type wireless receiving device in which deterioration of reception performance due to noise is suppressed, and a lighting device using the same.

It is a figure which shows the structure of the wireless receiving device in embodiment. It is a figure which shows the specific example of the structure of the wireless receiver device in embodiment. It is a figure which shows the structure of the local oscillator in an embodiment. It is a figure which shows the received signal strength detector (RSSI) configuration in an embodiment.

Hereinafter, embodiments of the wireless receiving device and the lighting device using the wireless receiving device according to the present disclosure will be described in detail with reference to the drawings. The embodiment described below is an example, and the wireless receiving device and the lighting device using the wireless receiving device according to the present disclosure are not limited thereto.

As shown in FIG. 1, the wireless receiver 100 according to the embodiment of the present disclosure includes an antenna 10, a switch 12, a high frequency amplifier 14, a mixer 16, a local oscillator 18, an intermediate frequency filter (IF filter) 20, a demodulator 22, and a receiver. It includes a signal strength detector (RSSI: Received Signal Filter) 24 and a control unit 26. FIG. 2 is a circuit diagram showing a specific configuration example of the wireless receiving device 100.

The wireless receiver 100 employs a superheterodyne system. The antenna 10 receives a high frequency fh radio signal. The high frequency amplifier 14 receives the input of the radio signal received by the antenna 10 via the switch 12, amplifies the radio signal of high frequency fh, and outputs the radio signal to the mixer 16. The mixer 16 mixes a high frequency fh radio signal amplified by the high frequency amplifier 14 and a local oscillation signal of the local oscillation frequency fy generated by the local oscillator 18 to output an intermediate signal of the intermediate frequency fm. Circuit design is complicated and component costs for configuring circuits are increased in order to modulate data for direct superimposition on high-frequency radio signals of several hundred MHz or higher, or to demodulate data for direct retrieval. To do. Further, in order to amplify the received weak radio signal to a signal strength that can be demodulated in a high frequency band, it is necessary to use a multi-stage amplifier. Therefore, the mixer 16 is used to convert the signal into an intermediate signal having a frequency several orders of magnitude lower than that of the transmitted / received wireless signal, and perform modulation / demodulation processing. The IF filter 20 is a bandpass filter that removes frequency components other than the target wave necessary for demodulation from the intermediate signal output from the local oscillator 18. In addition to the IF filter 20, a limiter circuit that limits the amplitude of the intermediate signal may be provided so as not to adversely affect the demodulation process in the demodulation unit 22. The demodulation unit 22 performs demodulation processing for extracting a necessary signal (data) from the intermediate signal output from the IF filter 20.

The local oscillator 18 includes a phase lock loop circuit (PLL circuit). As shown in FIG. 3, the PLL circuit includes a voltage controlled oscillator (VCO: Voltage Control Oscillator) 30, a loop filter 32, a 1 / n frequency divider 34, and a phase comparator 36. The PLL circuit frequency-converts the reference oscillation signal having the reference frequency fx generated in the reference oscillation unit and the multiplication unit (not shown) into the local oscillation signal having the local oscillation frequency fy. The reference oscillation unit has, for example, a variable capacitance unit composed of a switched capacitor, a varicap diode, or the like, and the control unit 26 outputs an oscillation signal by changing the capacitance of the variable capacitance unit. The multiplication unit frequency-converts the oscillation signal output from the reference oscillation unit into a reference oscillation signal having a reference frequency fx. The multiplication unit can be, for example, a frequency multiplication circuit that outputs a reference oscillation signal having a reference frequency fx that is an integral multiple of the frequency of the input signal by utilizing the non-linearity of the input / output characteristics of a transistor or the like. Further, a well-known Delayed Looped Loop circuit may be used as the multiplication unit. The phase comparator 36 of the PLL circuit converts the phase difference between the reference oscillation signal having the reference frequency fx and the feedback signal output from the 1 / n frequency divider 34 into a voltage and outputs the voltage. The voltage controlled oscillator 30 generates a local oscillation signal having a local frequency fy corresponding to the voltage output from the phase comparator 36 and outputs the local oscillation signal to the mixer 16. The voltage controlled oscillator 30 is generally configured to control the oscillation frequency according to changes in capacitance and inductance generated by applying an input voltage to a varicap (variable capacitance diode or the like) or an inductor. To. A low-pass filter called a loop filter 32 is arranged between the phase comparator 36 and the voltage controlled oscillator 30. Further, the local oscillation signal generated by the voltage controlled oscillator 30 is fed back to the phase comparator 36 via the 1 / n divider 34. The 1 / n frequency divider 34 divides the local oscillation signal into frequencies of 1/1n (n is a positive integer) and outputs the signal. With such a configuration, the local oscillator 18 is stable by synchronizing the phase difference between the reference oscillation signal having the reference oscillation frequency fx and the signal obtained by dividing the local oscillation signal having the local frequency fy output from the voltage control oscillator. It is possible to output the local oscillation signal.

The wireless receiver 100 according to the present embodiment includes an RSSI 24 that detects the intensity of an intermediate signal having an intermediate frequency fm output from the mixer 16, and when the intensity of the detected intermediate signal exceeds a predetermined reference value. The process of changing the local oscillation frequency of the local oscillation signal output from the local oscillator 18 is performed.

The RSSI 24 is a circuit that converts an intermediate signal having an intermediate frequency fm into a DC voltage. RSSI24 can be realized by, for example, the circuit shown in FIG. 1 of JP-A-2003-8371.

FIG. 4 shows a configuration example of RSSI24. The RSSI 24 is configured to output a DC voltage (output voltage RSSIout) according to the amplitude of the intermediate signal, using the intermediate signals as differential input voltages Vin and Vinx. The RSSI 24 includes a limiter amplifier unit 40 that limits and rectifies the amplitude of the differential input voltages Vin and Vinx, a voltage-current conversion unit 50 that converts rectified voltage signals Vo1 to Vo3 from the limiter amplifier unit 40 into current signals I1 to I3, and a voltage. It includes an output voltage generation unit 65 that obtains an output voltage RSSIout from the return currents of the current signals I1 to I3 from the current conversion unit 50. The limiter amplifier unit 40 includes three limiter amplifiers 41 to 43 including differential amplifiers. The limiter amplifiers 41 to 43 output the voltage signals Vo1 to Vo3 obtained by limiting the amplitude of the differential input voltages Vin and Vinx and rectifying them, respectively. The voltage-current converter 50 includes three voltage-current amplifiers 51 to 53. The three voltage-current amplifiers 51 to 53 convert the voltage signals Vo1 to Vo3 into current signals I1 to I3 and Ir1 to Ir3, respectively, and output them. Further, the voltage-current conversion unit 50 includes current sources 63 and 64 provided on the output side and current sources 61 and 62 constituting the current mirror circuit, respectively. The output voltage generation unit 65 takes the terminal voltage of the resistor connected to the current sources 63 and 64 as an input, converts the current signals from the current amplifiers 51 to 53, generates an output voltage RSSIout, and outputs the output voltage RSSIout.

However, the RSSI 24 is not limited to this, and may be configured to output a DC voltage according to the strength of the received signal. The DC voltage corresponding to the strength of the received signal generated by the RSSI 24 is input to the control unit 26.

The control unit 26 performs a process of changing the local frequency fy of the local oscillation signal generated by the local oscillator 18 according to the DC voltage input from the RSSI 24. Specifically, the control unit 26 performs a process of changing the local frequency fy of the local oscillation signal generated by the local oscillator 18 when the DC voltage input from the RSSI 24 becomes equal to or higher than a predetermined reference value. That is, the control unit 26 performs a process of changing the local frequency fy of the local oscillation signal when the DC voltage indicating the strength of the intermediate signal having the intermediate frequency fm becomes equal to or higher than a predetermined reference value.

As a specific example, the control unit 26 changes the local frequency fy of the local oscillation signal by outputting a control signal to the voltage controlled oscillator (VCO) constituting the local oscillator 18. For example, the control unit 26 changes the values of the varicaps and inductors included in the voltage controlled oscillator by outputting a control signal to the local oscillator 18. Thereby, the oscillation frequency in the local oscillator 18 is changed.

In this way, by changing the local frequency fy of the local oscillation signal output from the local oscillator 18 according to the strength of the intermediate signal, noise having a frequency component near the intermediate frequency fm is superimposed on the intermediate signal, and the signal is concerned. It is possible to reduce the influence of noise in the frequency band by changing the intermediate frequency fm of the intermediate signal generated by the mixer 16 when the intensity of the oscillator becomes too strong.

Here, when the antenna 10 is receiving a radio signal, the intensity of noise superimposed on the intermediate signal may not be correctly determined when the RSSI 24 generates a DC voltage corresponding to the intensity of the intermediate signal. There is. Therefore, the switch 12 may block the input of the radio signal from the antenna 10 to the high frequency amplifier 14 when detecting noise. The switch 12 may be configured to be able to switch between a state in which the radio signal received by the antenna 10 from the control unit 26 is input to the high frequency amplifier 14 and a state in which the antenna 10 and the high frequency amplifier 14 are cut off.

When the wireless transmission circuit is arranged side by side with respect to the wireless reception device 100, the antenna 10 and the high frequency amplifier 14 are separated by using the switch 12 when the antenna 10 is used by the wireless transmission circuit. Occasionally, noise may be detected by the DC voltage from RSSI24.

Further, the wireless receiving device 100 may be applied to receive a control signal to the lighting device. For example, by wirelessly transmitting a PWM signal from the controller to the lighting device, it can be applied as a wireless receiving device 100 for dimming level control for adjusting the brightness of lighting. At this time, the local oscillation frequency fy of the local oscillation signal by the local oscillator 18 may be changed when it is detected that the dimming level has increased by the control by the PWM signal.

As described above, according to the wireless receiver 100 according to the present embodiment, the influence of noise on the intermediate signal can be reduced. In particular, it is possible to reduce the influence of noise in the frequency band that directly affects the intermediate signal having the intermediate frequency fm.

10 antennas, 12 switches, 14 high frequency amplifiers, 16 mixers, 18 local oscillators, 20 filters, 22 demodulators, 24 received signal strength detectors (RSSI), 26 controls, 30 voltage controlled oscillators, 32 loop filters, 341 / n divider, 36 phase comparator, 40 limiter amplifier, 41-43 limiter amplifier, 50 voltage current converter, 51-53 current amplifier, 61-64 current source, 65 output voltage generator, 100 radio receiver.

Claims (4)

It is a superheterodyne type wireless receiver.
Mixer circuit and
A local oscillation circuit that outputs a local oscillation signal having a local oscillation frequency to the mixer circuit, and a local oscillation circuit.
An intensity detection circuit that detects the intensity of an intermediate signal having an intermediate frequency output from the mixer circuit,
With
When the intensity of the intermediate signal detected by the intensity detection circuit becomes equal to or higher than a predetermined reference value, the radio is characterized in that the local oscillation frequency of the local oscillation signal output from the local oscillation circuit is changed. Receiver. The wireless receiving device according to claim 1.
The local oscillator circuit includes a voltage control transmitter that constitutes a phase lock loop circuit.
Local oscillation by changing at least one of an inductor and a capacitor that determines the oscillation frequency of the voltage control transmitter when the intensity of the intermediate signal detected in the intensity detection circuit becomes equal to or higher than a predetermined reference value. A wireless receiving device characterized in that the local oscillation frequency of the local oscillation signal output from a circuit is changed. The wireless receiving device according to claim 1 or 2.
A switch for blocking a high-frequency input signal to the mixer circuit is provided.
A wireless receiving device characterized in that a high-frequency input signal to the mixer circuit is blocked by using the switch when detecting the strength of the intermediate signal in the strength detecting circuit. A lighting device including the wireless receiving device according to any one of claims 1 to 3.
A lighting device characterized in that the intermediate frequency of the intermediate signal output from the mixer circuit is changed when the dimming level is equal to or higher than a predetermined reference dimming level in response to a change in the PWM signal for setting the dimming level.