JPH07255016A - Compatible receiver for analog and digital broadcast - Google Patents

Abstract

PURPOSE:To provide the analog and digital broadcast compatible device which can receive an analog broadcast and a digital broadcast respectively with simple constitution. CONSTITUTION:The reception device is composed of frequency converter means 38 and 39 which convert a received image signal to an intermediate frequency, a detecting means 42 which detects the intermediate frequency signal outputted from those frequency converter means 38 and 39 and obtains a base-band signal, and synchronous detecting means 44-49 which synchronously detect the intermediate frequency signal outputted from the frequency converter means 38 and 39 and obtain an I-signal and a Q-signal; and the frequency converting means 38 and 39 are used in common in the reception state of the analog broadcast and the reception state of the digital broadcast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog / digital broadcast common receiving apparatus for receiving and reproducing both analog broadcast and digital broadcast of image information.

[0002]

As is well known, in recent television broadcasting, in addition to conventional analog broadcasting in which image information is broadcast as an analog signal, for example, satellite broadcasting or CATV.
Digital broadcasting has been introduced, in which image information is converted into digital data and broadcast, as is implemented in (cable television) broadcasting and the like.

FIG. 3 shows a conventional heterodyne receiver for receiving analog broadcasting. That is, the input terminal 11
Is supplied to the mixing circuit 13 via the amplifier circuit 12 and mixed with the local oscillation signal output from the local oscillation circuit 14 to be converted into a desired IF (intermediate frequency) signal. To be done. Then, the IF signal output from the mixing circuit 13 is a BPF (band pass filter).
After removing unnecessary harmonic components by 15, the signal is demodulated into a baseband signal by being supplied to the detection circuit 17 through the amplifier circuit 16 and taken out from the output terminal 18.

FIG. 4 shows a conventional QPSK (Quadrature Phase Shift Keying) receiver for digital broadcast reception.
That is, the RF signal supplied to the input terminal 19 is supplied to the mixing circuit 21 via the amplifier circuit 20 and mixed with the local oscillation signal output from the local oscillation circuit 22 to obtain a desired IF signal. To be converted. Then, the IF signal output from the mixing circuit 21 is supplied to the distribution circuit 25 via the amplification circuit 24 after the unnecessary harmonic components are removed by the BPF 23, and thus the phase detection circuit 2
6 and 27 respectively.

Of these signals, the IF signal supplied to the phase detection circuit 26 is a reference carrier signal output from a VCO (voltage controlled oscillator circuit) 28, which is distributed by a distribution circuit 29, and π / 2 by a phase shift circuit 30. It is converted to an I signal by being synchronously detected by the phase-shifted signal. This I signal is A /
It is supplied to the D (analog / digital) conversion circuit 31, converted into digital data, and taken out from the output terminal 32. The IF signal supplied to the phase detection circuit 27 is
The reference carrier signal distributed by the distribution circuit 29 is synchronously detected to be converted into a Q signal. The Q signal is supplied to the A / D conversion circuit 33, converted into digital data, and taken out from the output terminal 34.

In this case, the I signal and the Q signal after the synchronous detection, which are respectively output from the phase detection circuits 26 and 27, are supplied to the carrier recovery loop circuit 35 to perform a logical operation between the I and Q signals. , The oscillation frequency of the VCO 28 is controlled, and a reproduction loop for the reference carrier wave signal is formed here.

As described above, conventionally, in order to receive an analog broadcast, the heterodyne receiver for receiving the analog broadcast shown in FIG. 3 is required, and in order to receive the digital broadcast, the heterodyne receiver shown in FIG. 4 is used. Q for receiving the digital broadcast shown
As a PSK receiver is required, a dedicated receiver must be prepared for each of analog broadcasting and digital broadcasting, which causes a problem that it is very inconvenient for the viewer and economically disadvantageous. There is.

[0008]

As described above, conventionally, it is necessary to prepare a dedicated receiver for each of analog broadcasting and digital broadcasting, which is very inconvenient and economically disadvantageous to the viewer. I have a problem.

Therefore, the present invention has been made in view of the above circumstances, and provides a very good analog / digital broadcast common receiving apparatus capable of receiving an analog broadcast and a digital broadcast with a simple structure. The purpose is to do.

[0010]

A common receiver for analog / digital broadcasting according to the present invention comprises a frequency conversion means for converting a received image signal into an intermediate frequency and an intermediate frequency signal output from the frequency conversion means. The detection means for detecting the baseband signal and the synchronous detection means for synchronously detecting the intermediate frequency signal output from the frequency conversion means to obtain the I signal and the Q signal are provided. In the receiving state, the frequency converting means is commonly used.

[0011]

According to the above structure, the frequency conversion means is commonly used in the analog broadcast receiving state and the digital broadcast receiving state, so that the analog broadcast and the digital broadcast can be respectively used with a simple configuration. It becomes possible to receive.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, the RF signal supplied to the input terminal 36 is supplied to the mixing circuit 38 via the amplifier circuit 37 and mixed with the local oscillation signal output from the local oscillation circuit 39 to obtain a desired IF. Converted to a signal. Then, the IF output from the mixing circuit 38
The signal is amplified by the amplifier circuit 41 after removing unnecessary harmonic components by the BPF 40. Here, when analog broadcasting is being received, the IF signal output from the amplifier circuit 41 is demodulated into a baseband signal by being supplied to the detection circuit 42, and taken out from the output terminal 43.

On the other hand, when digital broadcasting is being received, the IF signal output from the amplifier circuit 41 is supplied to the distribution circuit 44, whereby the phase detection circuits 45 and 4 are detected.
Each is led to 6. Among them, the IF signal supplied to the phase detection circuit 45 is to be synchronously detected by a signal in which the reference carrier signal output from the VCO 47 is distributed by the distribution circuit 48 and is phase-shifted by π / 2 by the phase shift circuit 49. Is converted into an I signal. This I signal is supplied to the A / D conversion circuit 50, converted into digital data, and taken out from the output terminal 51. Further, the IF signal supplied to the phase detection circuit 46 is synchronously detected by the reference carrier wave signal distributed by the distribution circuit 48 to be converted into a Q signal. The Q signal is supplied to the A / D conversion circuit 52, converted into digital data, and taken out from the output terminal 53.

In this case, the I signal and the Q signal after the synchronous detection, which are respectively output from the phase detection circuits 45 and 46, are supplied to the carrier recovery loop circuit 54 to perform a logical operation between the I and Q signals. , The oscillation frequency of the VCO 47 is controlled, and a reproduction loop of the reference carrier wave signal is formed here.

According to the configuration of the above embodiment, regardless of whether analog broadcasting or digital broadcasting is received,
Since the input terminal 36 to the amplifier circuit 41 are commonly used, it is possible to receive the analog broadcast and the digital broadcast with a simple configuration.

FIG. 2 shows a modification of the above embodiment, in which the same parts as in FIG. 1 are designated by the same reference numerals.
In this modified example, analog broadcasting adopts FM modulation, and digital broadcasting adopts a modulation method such as MSK (Minimum Phase Shift Keying) method in which a clock can be taken out by performing FM detection. Is intended for. In this case, even the detection circuit 42 (in this case, the FM detection circuit) can be a shared portion.

First, reception of analog broadcasting can be described in the same manner as in the case of FIG. When receiving digital broadcasting, the FM detection output from the detection circuit 42 is supplied to the clock reproduction circuit 55 to reproduce the clock. This clock is used as a system clock for each unit of the receiving device and also as a symbol timing for phase synchronization of the reference carrier signal output from the VCO 47. That is, the I and Q signals after synchronous detection output from the phase detection circuits 45 and 46 are supplied to the comparison circuits 56 and 57, respectively, and compared with the reference value.

The comparison outputs of the comparison circuits 56 and 57 are supplied to the carrier wave synchronization circuit 58 and used to generate a control signal for controlling the oscillation frequency of the VCO 47. At this time,
The clock output from the clock recovery circuit 55 is used to generate the control signal. The control signal output from the carrier synchronization circuit 58 is converted into a voltage signal by the loop filter 59 and supplied to the VCO 47, so that the reference carrier signal is generated. The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

[0019]

As described above in detail, according to the present invention,
It is possible to provide a very good analog / digital broadcast shared receiving device that can receive an analog broadcast and a digital broadcast with a simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a modification of the embodiment.

FIG. 3 is a block diagram showing a conventional heterodyne receiver for analog broadcast reception.

FIG. 4 is a block diagram showing a conventional QPSK receiver for digital broadcast reception.

[Explanation of symbols]

11 ... Input terminal, 12 ... Amplifying circuit, 13 ... Mixing circuit, 1
4 ... local oscillator circuit, 15 ... BPF, 16 ... amplifier circuit, 1
7 ... Detection circuit, 18 ... Output terminal, 19 ... Input terminal, 20
... Amplifying circuit, 21 ... Mixing circuit, 22 ... Local oscillation circuit, 2
3 ... BPF, 24 ... Amplifier circuit, 25 ... Distribution circuit, 26,
27 ... Phase detection circuit, 28 ... VCO, 29 ... Distribution circuit,
30 ... Phase shift circuit, 31 ... A / D conversion circuit, 32 ... Output terminal, 33 ... A / D conversion circuit, 34 ... Output terminal, 35 ... Carrier reproduction loop circuit, 36 ... Input terminal, 37 ... Amplification circuit, 38 ... Mixing circuit, 34 ... Local oscillation circuit, 40 ... BP
F, 41 ... Amplification circuit, 42 ... Detection circuit, 43 ... Output terminal, 44 ... Distribution circuit, 45, 46 ... Phase detection circuit, 47
... VCO, 48 ... Distribution circuit, 49 ... Phase shift circuit, 50 ... A
/ D conversion circuit, 51 ... Output terminal, 52 ... A / D conversion circuit, 53 ... Output terminal, 54 ... Carrier recovery loop circuit, 5
5 ... Clock recovery circuit, 56, 57 ... Comparison circuit, 58 ...
Carrier wave synchronizing circuit, 59 ... Loop filter.

Claims (1)

[Claims] 1. A frequency conversion means for converting a received image signal into an intermediate frequency, a detection means for detecting an intermediate frequency signal output from the frequency conversion means to obtain a baseband signal, and the frequency conversion means. And a synchronous detection means for synchronously detecting the output intermediate frequency signal to obtain an I signal and a Q signal, so that the frequency conversion means can be commonly used in an analog broadcast receiving state and a digital broadcast receiving state. An analog / digital broadcast shared receiver characterized by being configured.