JPS58157214A - Digital receiver - Google Patents

Abstract

PURPOSE:To attain analog display of reception frequency accurately, by adjusting the indication of a meter when a maximum frequency of each reception frequency band is received, in a digital receiver using analog display in common. CONSTITUTION:When a switch SW1 is operated to select the FM reception band, a transistor (TR)Q2 is turned off with the output of a band selector circuit 19. A DC level V1 at the maximum frequency F1 is impressed to the meter 20 via a TRQ1 and a semi-fixed resistor VR to adjust the meter so as to indicate the maximum indicating position. In selecting the AM reception band with a switch SW2, the TRQ2 is turned on. A resistor R3 is selected so that a DC level V2 at the maximum frequency F2 is the DC level V1 and the level is applied to the meter 20, allowing to adjust the maximum indicating position at the maximum frequency F2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tit/tal receiver that performs tuning operations for a plurality of receiving frequency bands in a tint-like manner, and displays the received frequencies in an analog manner with an analog meter. By setting the analog meter so that it indicates the same value when the highest frequency in the frequency band is received, accurate analog display can be performed.

In recent years, many receivers have been used that perform tuning operations in a tintal manner using a synthesizer method using a PLL. There are also things that can be displayed in an analog way.

In a digital receiver that also uses analog display and is capable of receiving multiple reception frequency bands (for example, FM and FM), there is a problem that the indicated value of the analog meter differs for each band. be. That is,
The tit/tal signal used during PLL has a different number of steps depending on the receiving band frequency and its channel space frequency (the frequency between the most adjacent stations), and is an analog signal obtained by D/M conversion. A level difference also occurs in the signal.

Figure 1 shows the relationship between reception frequency and DC level by region, and shows the relationship between reception frequency (11), reception band (II),
! : There is a difference in DC level of V2-11. However, by receiving such two reception frequency bands, each DC
When the analog meter is driven by the level, the reception band (1)
There is a drawback that the deflection angle at the time of the reception band (tl) is smaller than that at the reception band (tl).

The present invention provides a digital receiver that solves these conventional drawbacks.

Hereinafter, one embodiment of the present invention will be explained with reference to FIG.
A detection stage, 6 an amplification stage, and 7 a speaker constitute a normal FM reception system. 8 is a local oscillator composed of a voltage controlled oscillator; 9 is a programmable frequency divider that divides the output frequency of the local oscillator 8; 1o is a reference oscillator;
1 is a phase comparator that compares the phases of the output of the programmable frequency divider 9 and the output of the reference oscillator 1o; 12 is the phase comparator 1;
This is a low-pass filter that filters the output of 1 into low-frequency waves.

The oscillation frequency of the local oscillator 8 is varied by the output of the low-pass filter 12. These constitute a well-known PLL circuit, and by manually or automatically setting a digital signal for setting the division ratio from the division ratio setting circuit 13 to the programmable frequency divider 9, the local oscillation frequency can be adjusted accordingly. changes, and a channel selection operation is performed.

On the other hand, 14, 15, and 16 are an AM antenna, an AM receiving circuit, and a speaker that constitute an AM receiving system.

Here, for convenience of explanation, the speaker 16 is shown separately from the speaker 7, but one of the speakers is shown as FM and A.
Needless to say, it can be shared with M. It goes without saying that the amplification stage in the FM receiver circuit 15 can also be used in common with the amplification stage 6 on the FM side.
As in the case of , an AM PLL is incorporated, but a part of this PLL can also be shared with the FM PLL.

17 is the programmable frequency divider 9 on the FM side and a DM converter that converts the digital signal set thereon into an analog signal, 18 is an integration circuit that integrates the output, and 19 is the switch Sw'l, SW2. 20 is an analog meter; and 21 is an adjustment circuit that adjusts the deflection of the analog meter 20. This adjustment circuit 21 includes transistors Q+,
Q2, a semi-fixed resistor VR, a switch Sw3 that is turned on and off when switching the channel space frequency, and a resistor R.
It is composed of 1 to R5.

In the above configuration, since the channel selection operation itself is well known, the explanation will be omitted, and the operation of the analog meter 20 will be explained.

When the switch Swj is operated to switch to the state of receiving FM, the output of the band selector circuit 19 turns off the transistor JQ2. Here, V of transistor Q1
The bias resistor R2 for AT characteristic correction is appropriately selected and set so that the pointer of the analog meter 20 swings appropriately between the zero potential of the lowest reception frequency and the vax of the highest reception frequency. Adjust the pointer of the meter 20 so that it reaches the maximum deflection angle during reception. That is, assuming that the receiving band (I) in FIG. 1 is FM, the DC level v1 at the highest frequency F1 is determined by transistor Q.
+, applied to the meter 20 via the semi-fixed resistor VR,
The pointer of the meter 2o is adjusted by the semi-fixed resistor VR so that it indicates the maximum deflection position.

In this way, when receiving each FM frequency, the digital signal sent to the programmable frequency divider 9 will be
The D/M converter 17 performs D/M conversion, and the output thereof is sent to a resistor R1, a transistor Q1 . The signal is applied to the analog meter 20 through the semi-fixed resistor VR, and the pointer of the meter 2° moves from the zero deflection angle to the maximum weight, thereby displaying the FM reception frequency in an analog manner.

Next, when the switch Sw2 is operated to switch to the state where the signal M is received, the transistor Q2 is turned on by the output of the band selector circuit 19, and the output of the integrating circuit 18 is changed to the state of receiving the signal M.
, Rs and applied to J20. Therefore, at the highest frequency (F2 in the example in Figure 1), Da
Select the value of resistor R5 so that level v2 is divided by resistors R+ and R1 to become vl, and if this voltage is applied to meter 20, the pointer will indicate the maximum deflection position at the highest frequency. .

In addition, for export receivers, the channel space frequency is 200KH2, 450KH2 for FM, and 10KH2 for AM.
Some devices have a function of switching between KHz and 9 KHz, and even in this case, the DC level changes depending on the switching of the channel space frequency, as shown in the receiving band (1), GV) in FIG. 1, for example.

Therefore, as shown in FIG. 2, a resistor R4 and a switch Sw3 are connected in parallel with the resistor R5, and the switch Sw3 is closed in conjunction with the switching of the channel space frequency.
The output of is the parallel composite value R2/ of resistor R1 and resistor R2, Rs.
If the voltage is divided by R5 and applied to the meter 20, the 2° deviation of the meter can be adjusted in the same way as when changing the band.

In this way, the present invention digitally receives different reception frequency bands, generates an analog signal based on the digital signal at that time, drives a meter with this analog signal, and displays the reception frequency in an analog manner. ,
Since the meter deflection positions are made to match when receiving the highest frequency of each receiving frequency band, the receiving frequency can be accurately displayed in analog form.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between reception frequency and D (3 levels), and FIG. 2 is a circuit diagram of an embodiment of the present invention. 1 to 7...FM reception system, 8 to 12.・・・・・・
PLL, 13... Division ratio setting circuit, 14 to 16
...Muy receiving system, 17...0 converter, 18...integrator circuit, 19...band selector circuit, 2o...・Analog meter, 21・
...adjustment circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 4: Small amount of leftover fu

Claims (1)

[Scope of Claims] A plurality of receiving means for receiving a plurality of mutually different receiving frequency bands according to tintal signals, and D converting digital signals in each of the receiving means into analog signals.
and an analog meter that displays a reception frequency in an analog manner according to the analog signal output from the DA conversion means. A digital receiver comprising means for making the indicated values of the analog meter coincide with the same value when receiving the highest frequency of each of the receiving frequency bands.