JPS6228898B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device suitable for use in a receiver such as a radio receiver. In particular, the present invention relates to a display device suitable for use in a receiver such as a radio receiver. It is an object of the present invention to provide a display device that can easily display whether radio waves of high quality are being received.

In recent radio receivers, basic performances such as S/N (signal-to-noise ratio) and distortion characteristics have been significantly improved and are now at a high level.

However, it is highly questionable whether listeners are using the radio receiver to its full potential. In order to take advantage of the performance of a radio receiver, it is necessary to maintain high-quality tuning at the maximum antenna input level and without interference noise, multipath, beat interference, etc. However, in conventional radio receivers, Because there was no display device to display the quality of the received radio waves, it was extremely difficult for the listener to make full use of the receiver's performance and receive high-quality reception.

Conventional radio receivers derive an intermediate frequency signal that is not subject to amplitude limitations from the intermediate frequency stage of the radio receiver, and level detect the intermediate frequency signal to obtain a field strength display signal, which can be used as a signal meter, etc. An electric field strength display device that drives the display, and a tuning display that detects the DC component included in the detection output signal from the detection stage and drives a display such as a center zero meter using the DC component to display the tuning state. at least one side with the device. The display device of such a radio receiver can display the best reception condition in terms of level or frequency, and can tune according to the display, but it is difficult to prevent interference caused by radio wave propagation. It was not possible to display the overall quality of the received radio waves, including the

The present invention has been made in view of the above points, and will be described below based on embodiments and with reference to the drawings.

Here, various characteristics of the radio receiver will be briefly explained. First, the S/N and distortion characteristics generally correspond to the antenna input level (field strength of received radio waves), and tend to deteriorate as the antenna input level decreases. However, the antenna input level is
Since it corresponds to the IF signal level, reception with good S/N and distortion characteristics can be achieved by detecting the IF signal level and performing tuning such that the IF signal level is the maximum. On the other hand, it is known that when the S/N and distortion characteristics deteriorate, noise included in a high frequency band above the signal band increases. Therefore, instead of using an IF signal, high frequency noise can be used to achieve reception with good S/N and distortion characteristics.

Furthermore, multipath interference caused by radio waves taking multiple propagation paths is caused by the radio waves being amplitude-modulated and phase-modulated by the interference waves. This multipath interference is difficult to remove on the receiver side and is unrelated to the antenna input level, so it could not be displayed by conventional field strength display devices. However, when receiving multipath interference, the high frequency noise contained in the received signal increases, so multipath interference can be detected by detecting the high frequency noise.

Furthermore, high frequency noise in the received signal also increases when pulse disturbances occur, such as beat interference caused by interference between broadcasting stations.

Therefore, by detecting high frequency noise and displaying its amount, it is possible to detect the amount of various interferences contained in received radio waves, and by adjusting the tuning state according to the detection state, good reception can be achieved. You can get the status.

FIG. 1 shows an embodiment of the present invention.
is the antenna for receiving radio waves, 2 is antenna 1
Amplify the RF (radio frequency) signal received by
RF amplification stage; 3 is a mixing stage that mixes the RF signal and the local oscillation signal from local oscillation stage 4 to generate an IF (intermediate frequency) signal; 5 is an IF obtained from the mixing stage;
IF amplification stage that amplifies the signal, 6 is a detection stage that detects the IF signal and generates an LF (low frequency) signal, 7 is LF
Stereo that generates left and right stereo signals from the signal
This is an MPX (multiplex) stage. Also, 8
9 is a signal level detection circuit that detects the level of the IF signal that is not subjected to amplitude limitation;
a first drive signal generation circuit that generates a drive signal; 10;
11 is a DC component detection circuit that detects the DC component of the signal obtained at the output terminal of the detection stage 6, and 11 is a second drive signal generation circuit that generates a second drive signal in accordance with the output signal of the DC component detection circuit 10. , 12 is a tuning indicator such as a center zero meter or a light emitting diode driven by the second drive signal, 13 is a noise detection circuit that detects a high frequency noise component contained in the output signal of the detection stage 6, and 14 is a noise detection circuit. An amplifier circuit 15 rectifies and amplifies the output signal of the detection circuit 13, a correction circuit 15 corrects the output signal of the amplifier circuit 14, and a third drive signal 16 that generates a third drive signal in accordance with the output signal of the correction circuit 15. A drive signal generation circuit 17 switches the first drive signal from the first drive signal generation circuit 9 or the third drive signal from the third drive signal generation circuit 16 in accordance with the switching signal obtained from the DC component detection circuit 10. The output switching circuit and 18 are indicators such as meters driven by the output signal of the switching circuit 17.

Next, the operation will be explained. The signal received by antenna 1 is amplified by RF amplification stage 2, and then converted to IF by mixing stage 3.
The signal is converted into a signal, amplified at the IF amplification stage 5, detected at the detection stage 6, and separated into left and right stereo signals at the stereo MPX stage 7. At that time, the level of the IF signal in the IF amplification stage 5 is detected by the signal level detection circuit 8, and the first drive signal generation circuit 9 generates a first drive signal according to the output signal level of the level detection circuit 8.
A drive signal is generated. Further, the high frequency noise contained in the output signal of the detection stage 6 is transmitted to the noise detection circuit 13,
The signal is applied to the third drive signal generation circuit 16 via the amplifier circuit 14 and the correction circuit 15, and a third drive signal corresponding to the amount of high frequency noise is generated at its output.

The switching circuit 17 has a configuration as shown in FIG. 2, and has a first input terminal 1 to which a first drive signal is applied.
9 and a second input terminal 2 to which a third drive signal is applied.
0, an output terminal 21 connected to the display 18,
a control terminal 22 to which a control signal is applied, and a switch 23 that switches from a first state indicated by a solid line to a second state indicated by a dotted line in accordance with the control signal applied to the control terminal 22; A NAND circuit whose second input terminal is connected to the output side of the DC component detection circuit 10 via the circuit 24, to the positive power supply (+Vcc) via the resistor 25, and whose output terminal is connected to the control terminal 22 of the switch 23, respectively. 26 and the NAND circuit 26
A manual switch 27 is inserted between the second input terminal of the switch and ground.

Now, if the tuning state is incomplete and the receiver is in the tuning state in range A or range C of the output signal characteristics (FIG. 3) of the DC component detection circuit 10, the output signal of the detection circuit 24 is 0”. Furthermore, if the manual switch 27 is in the open state as shown, the second input of the NAND circuit 26 is "1".
Therefore, the output of the NAND circuit 26 becomes "1",
The switch 23 is in a solid line state, the first drive signal applied to the first input terminal 19 is output to the output terminal 21, and the display 18 displays the electric field strength of the received radio wave represented by the first drive signal.

When the tuning operation is performed and the tuning state is in range B in FIG. 3, the output of the detection circuit 24 becomes "1",
The output of the NAND circuit 26 becomes "0". For that reason,
The switch 23 changes to the state indicated by the dotted line, the third drive signal applied to the second input terminal 20 is output to the output terminal 21, and the display 18 displays the quality of the received radio wave represented by the third drive signal. .

The range in which the synchronized state is in Figure 3 can be determined by the second
It is displayed using the drive signal generation circuit 11 and the tuning display 12. Since this is a conventionally commonly used display, the details will be omitted.

The switch 23 is in the dotted line state, and the display 18
When the manual switch 27 is pressed while displaying the quality of received radio waves, the second input terminal of the NAND circuit 26 becomes "0" and the output terminal of the NAND circuit 26 becomes "1". Therefore, the switch 23 changes to the solid line state, the first drive signal is derived from the output terminal 21, and the display 18 comes to display the field strength of the received radio wave. Therefore, if you wish to display the field strength of the received radio waves while the quality of the received radio waves is being displayed, the manual switch 27 can be pressed.

Here, the display of the quality of received radio waves will be explained in detail.
FIG. 4 schematically shows the relationship between the tuning frequency and the third drive signal for the first to fourth stations (characteristic diagrams A to D correspond to each other). When displaying the quality of received radio waves, the display is performed between the reference noise level X and the maximum noise level Y, and the closer to the reference noise level X, the better the quality. Displaying the quality of received radio waves is related to the quality of the received radio waves themselves and the tuning state. For example, the fourth station indicated by the solid line D in FIG. 4 has the best quality of the received radio waves itself, but if the quality is out of tune, it becomes worse than the third station indicated by the solid line C.

Therefore, when checking the relative quality of each station, the best scores of each station must be compared. Therefore, in the present invention, the DC output of the detection stage 6 and the switching circuit 17 are used to display the quality of the received radio waves only in the vicinity of the tuning point where display is particularly necessary. The quality of received radio waves may be displayed for the entire tuning range, but in that case, the display range of the display must be expanded, and the display range corresponding to the vicinity of the originally required tuning point becomes narrower. causing inconvenience.

Note that the correction circuit 15 shown in FIG. 1 is arranged to lower the reference noise level shown in FIG. 4. The reference noise level corresponds to noise and display errors generated by the receiver itself including the display, but if corrected by the correction circuit 15, the reference noise level can be minimized.

As described above, the present invention adds a completely new function to the receiver, and is excellent in that it can accurately and effectively display the quality of received radio waves.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention, FIG. 2 is a circuit block diagram showing a specific example of the switching circuit of FIG. 1, and FIGS. 3 and 4 are used to explain the present invention. FIG. Explanation of main figure numbers, 8...Signal level detection circuit,
9, 11, 16... Drive signal generation circuit, 13...
Noise detection circuit, 17... switching circuit.

Claims (1)

[Claims] 1. A first circuit that generates a first signal according to the electric field strength of received radio waves, a second circuit that generates a second signal that indicates the tuning state of the receiver, a demodulation circuit that demodulates the received radio waves, and the demodulation circuit. a third circuit that generates a third signal according to the high frequency noise contained in the output signal of the output signal; a display; the first and third signals are inputted; A display device comprising a switching circuit that outputs a signal or a third signal and applies it to the display device, and is configured to switch and display the electric field strength and quality of received radio waves according to the tuning state of a receiver.