JPH0662330A - Wide band reception tuner - Google Patents

Abstract

PURPOSE:To narrow an oscillation frequency band by providing a first band setting means for which the frequency of a difference between a local oscillation frequency and the intermediate frequency of intermediate frequency signals is defined as a tuning frequency and a second band setting means for which the sum of them is defined as the tuning frequency. CONSTITUTION:When a band 1 is selected by selecting the contact (a) of changeover switches 100 and 107, input signals supplied from the input terminal 3 of a tuner are supplied through an LPF 101, an amplifier 103, the contact (a) of a tracking filter 105 and the changeover switch 107 to a mixer 108. At this time, the tuner input signals whose frequency is below 2050MHz pass through the LPF 101. On the other hand, when the band 2 is selected by switching the changeover switches 100 and 107 to the contact (b), the input signals supplied from the input terminal of the tuner are supplied through an HPF 102, the amplifier 104 and the contact (b) of the tracking filter 106 and the changeover switch 107 to the mixer 108. At this time, the tuner input signals whose frequency is above 2050MHz pass through the HPF 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide band receiving tuner, and more particularly to a wide band receiving tuner used for receiving satellite broadcasting having a wide frequency broadcasting band.

[0002]

2. Description of the Related Art In recent years, satellite broadcasting using broadcasting satellites or communication satellites has been performed in various places. Horizontal or vertical polarization transmitted from the satellite (hereinafter referred to as "HV polarization")
Signal is received by antenna 1 as shown in FIG.
LNB (Low Noise Block Downco
(nverter) 2 frequency-converted and supplied to the input terminal 3 of the BS tuner.

In the BS tuner, after being amplified by the high frequency amplifier 4, the channel is selected by the tracking filter 5, and the frequency F _RF of the selected channel is mixed by the mixer 6 with the upper local frequency F _{LO +} from the VCO 7. And the frequency is F
_iF (F _iF = F _{LO +} −F _RF ) converted into an intermediate frequency signal,
It is supplied to the intermediate frequency signal processing unit (not shown). 8 in the figure
Is a PLL tuning circuit.

On the other hand, the European broadcasting satellite ASTRA,
One of the methods of receiving signals from 1A, 1B, 1C, etc. is to rearrange the channels of H polarization and V polarization, and the tuner in this case has a tuner of 950 MHz to 2600 MH.
A wide reception frequency range of z is required. Above ASTR
The frequency arrangement of each satellite A, 1A, 1B, 1C is as shown in FIG. 4, and FIG. 5 shows the detailed channel arrangement.

FIG. 6 shows an H.264 signal in which the H polarization and V polarization of satellite broadcasts having the above channel arrangement are simultaneously received and the channels of the respective satellites are rearranged. It is a V simultaneous reception type LNB. In FIG. 6, the received signal guided to the waveguide stripline converter 9 is separated into the H polarization and the V polarization, and then the H.H.
LNA (Low Noise Amplify) for V polarization
er) 10, 11 and amplified in H. A signal of a frequency of a predetermined channel is derived via band-pass filters for V polarization (hereinafter, referred to as “BPF”) 12 and 13.

The above H. The input signals derived from the BPFs 12 and 13 for V polarization are H.264. V polarization mixer 14,
The H polarized wave signal or the V polarized wave signal is supplied to 15 and mixed with the local oscillation frequency of 10 GHz or 9.1 GHz from the local oscillator 16 or 17 and frequency-converted into an intermediate frequency signal. The frequency-converted intermediate frequency signals are amplified by the intermediate frequency amplifiers 18 and 19, respectively, and then combined into a single signal by the combiner 20 and output from the output terminal 21 of the LNB as an LNB output.

FIG. 7 shows the H.264 signal shown in FIG. V simultaneous reception type L
1A, 1B, and 1C in the figure show broadcasting satellite names ASTRA, 1A, 1B, and 1C, respectively. V indicates H polarization and V polarization, respectively. In this case, the reception frequency band of the reception tuner is 950 MHz to 2600 MHz, and a wide band is required.

In the receiving tuner, the above-mentioned receiving frequency band 950
When trying to receive a signal of MHz to 2600 MHz,
To set the intermediate frequency F _iF of the intermediate frequency signal output to 480 MHz, the local oscillation frequency F _{LO +} is 1 from F _{LO +} = F _RF + F _iF
It becomes 430 MHz to 3080 MHz, and the variable range becomes extremely wide.

FIG. 8A shows an example of a wide band receiving satellite tuner in which two VCOs are provided and the local oscillation frequency is divided into two in order to secure a wide range of variable frequencies of the local oscillation circuit as described above. In FIG. 8, the input terminal 3 of the tuner
The input signal as shown in FIG. 7 supplied to the high-pass filter (hereinafter referred to as “LPF”) 22 and the high-pass filter (hereinafter referred to as “HPF”) 23 are supplied to the 1700 MHz.
The signal is divided into two signals of z or less and 1850 MHz or more, respectively amplified by an amplifier 24.25, then tuned by tracking filters 26 and 27, and supplied to mixers 28 and 29.

In the mixer 28 or 29, the signal of the frequency F _RF1 or F _RF2 from the tracking filter 26 or 27 and 1430 MHz to 2 from the VCO 30 are transmitted.
Signal of local oscillation frequency F _LO1 of 180 MHz or VC
The signals of the local oscillation frequency F _LO2 of 2330 MHz to 3080 MHz from O31 are mixed to derive the intermediate frequency signal of the intermediate frequency F _iF1 or F _iF2 .

The intermediate frequency signals of the intermediate frequencies F _iF1 and F _iF2 derived from the mixers 28 and 29 are selectively switched by the switch 33, and the intermediate frequency signal processing unit (not shown) in the next stage. It is supplied and the PLL circuit 3
2 is selectively connected to the VCO 30 or 31 by a switch 34.

FIG. 8 (b) is another conventional example in which the oscillation frequency range of the VCO is made as narrow as possible in the conventional example shown in FIG. 8 (a), and the portion corresponding to FIG. 8 (a) is the same. The reference numerals are given and the description is omitted. In FIG. 8B, 35
Is a VCO that oscillates a frequency of 1165 MHz to 1540 MHz, and the oscillation signal derived from the VCO 35 is doubled by the multiplier 37 and passed through the HPF 36 to generate 2330 M.
A local oscillation signal of Hz to 3080 MHz is derived.

[0013]

When the input signal is a signal in a wide frequency range such as 950 MHz to 2600 MHz as described above, an intermediate frequency signal is generated by using the upper local oscillation frequency as in the conventional device. In, there are the following problems.

Since the variable range of the local oscillation frequency is wide, two VCOs and mixers are required. The prescaler IC used in the PLL channel selection circuit needs to be one that can be used even at a frequency of 3000 MHz or higher, which makes the circuit configuration very expensive. When a multiplier is used as shown in FIG. 8B, the above problem is solved, but a multiplier is required and
A high-pass filter that cuts the original oscillation component of the VCO is also required, and the circuit configuration becomes complicated and expensive.

An object of the present invention is to solve the above problems and to provide a wide band receiving tuner for receiving a wide band signal of 950 MHz to 2600 MHz or the like with an inexpensive and simple circuit configuration.

[0016]

In order to solve the above problems, the present invention solves the above-mentioned problems by using a VCO whose local oscillation frequency is controlled by a PLL tuning circuit and a local oscillation signal from the VCO and a reception signal which is to be selected. And a mixer for mixing and outputting an intermediate frequency signal,
First band setting means for setting a first band having a frequency of a difference between the local oscillation frequency of the local oscillation signal from O and the intermediate frequency of the intermediate frequency signal as the first tuning frequency of the received signal; , A second band setting means for setting a second band having a frequency that is the sum of the local oscillation frequency and the intermediate frequency as the second channel selection frequency of the received signal.

[0017]

Therefore, the reception frequency band is, for example, 950 MHz.
In the case of ˜2600 MHz, for example, 2050 MHz is predetermined as an intermediate frequency, and the reception frequency is 9
At 50 MHz to 2050 MHz, the first band is set by the first band setting means. In this case, VCO
The oscillation frequency of is 1 when the intermediate frequency is 480MHz.
It becomes 430MHz-2530MHz. On the other hand, when the reception frequency is in the range of 2050 MHz to 2600 MHz, the second band setting means sets the second band. In this case, the oscillation frequency of the VCO is 1570 MHz
It becomes 2120 MHz. Therefore, VCO is 1430MH
It is only necessary to oscillate in the range of z to 2530 MHz, the oscillation frequency can be lowered, and the oscillation frequency band can be narrowed.

[0018]

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, 100 is an LP for passing an input signal of 950 MHz to 2600 MHz from the LNB supplied to the input terminal 3 of the tuner and passing a signal of 2050 MHz or less.
HP that passes signals of F101 and 2050MHz or higher
It is a changeover switch for selectively supplying to F102.
Reference numerals 3 and 104 are amplifiers for amplifying the outputs of the LPF 101 and HPF 102.

Reference numerals 105 and 106 denote tracking filters for selecting a desired channel by the PLL circuit 110 from the outputs of the amplifiers 103 and 104, and 107
Is a changeover switch for selectively guiding the output of the tracking filter 105 or 106 to the mixer 108. The changeover switch 107 and the changeover switch 100 make a contact a when the frequency of the channel to be selected is 2050 MHz or less, and 2050 MHz. In the above case, the contact b is interlocked and selected to perform band switching.

The mixer 108 has an oscillation frequency F _LO of 14
The local oscillation signal of 30 MHz to 2530 MHz and the input signals F _RF1 and F _RF2 are mixed, and the intermediate frequency F _iF is 480 MHz.
The intermediate frequency signal of is derived.

Now, when the contact a of the changeover switches 100 and 107 is selected and band 1 is selected, the input signal supplied from the input terminal 3 of the tuner is the LPF 101 and the amplifier 1.
03, tracking filter 105 and changeover switch 10
7 is supplied to the mixer 108 via the contact point a. At this time, the tuner input signal having a frequency of 2050 MHz or less passes through the LPF 101.

Now, suppose that the PLL tuning circuit 110 causes 95
When trying to select a channel of 0 MHz, the tracking filter 105 sets the image frequency of 1910 MHz (950 MHz + 2 × 480) for the signal of 950 MHz.
It becomes an image filter that works to sufficiently attenuate (MHz). At this time, the local oscillation frequency F _LO of the VCO 109 becomes 1430 MHz, and this local oscillation signal is supplied to the mixer 108. As a result, the mixer 108
An intermediate frequency signal with an intermediate frequency F _iF of 430 MHz-950 MHz = 480 MHz is derived.

On the other hand, when the changeover switches 100 and 107 are changed over to the contact b and the band 2 is selected, the input signal supplied from the input terminal 3 of the tuner causes the HPF 102, the amplifier 104, the tracking filter 106 and the contact b of the changeover switch 107. It is supplied to the mixer 108 via. At this time, the tuner input signal having a frequency of 2050 MHz or higher passes through the HPF 102.

Now, suppose that the PLL tuning circuit 110 causes 20
When trying to select a channel of 50 MHz, the tracking filter 106 sets the image frequency of 1090 MHz (2050 MHz-2 × 4) for the signal of 2050 MHz.
The image filter works so as to sufficiently attenuate (80 MHz). At this time, the local oscillation frequency F _LO of the VCO 109 becomes 1570 MHz, and this local oscillation signal is supplied to the mixer 108. As a result, the mixer 108 derives an intermediate frequency signal with an intermediate frequency F _iF of 2050 MHz−1570 MHz = 480 MHz.

The same operation is performed when selecting another channel. That is, the channel to be selected is 2050
In the case of MHz or less, the contact a of the changeover switches 100 and 107 is selected, and the frequency F _RF1 of the input signal of the channel to be received which is selected by the tracking filter 105 is selected.
Is the mixer 1 from the local oscillation frequency F _LO from the VCO 109.
Intermediate frequency F _iF = 4 of the intermediate frequency signal derived from 08
Control is performed so that the value is obtained by subtracting 80 MHz.

The channel to be selected is 2050.
When the frequency is higher than MHz, the contact b of the changeover switches 100 and 107 is selected, and the frequency F of the input signal of the channel selected by the tracking filter 106 to be received is F.
_RF2 is the local oscillation frequency F _LO from the VCO 109 and the intermediate frequency F _iF of the intermediate frequency signal derived from the mixer 108 =
Control is performed so that the value will be 480 MHz.

In the above circuit, the input signal is 2050
Band 1 below MHz and Band 2 above 2050 MHz
The mixer 108 is used in common and the outputs of bands 1 and 2 are derived from the mixer 108. However, if there is a difference in the intermediate frequency output of the intermediate frequency F _iF from the mixer 108 between band 1 and band 2, an amplifier The gains of 103 and 104 may be adjusted.

In the above embodiment, the band switching frequency is set to 2050 MHz, but this is for the following reason. That is, when a frequency lower than 2050 MHz is set as the boundary frequency, the difference between the higher harmonic of the local oscillation frequency F _LO- and the intermediate frequency F _iF = 480 MHz (2
The frequency of (× F _LO −−F _iF ) enters the reception frequency region, and it becomes difficult to sufficiently remove this with the tracking filter. As a result, it interferes with the signal to be selected. The band switching frequency is set to the above value in order to avoid such a problem. FIG. 2 is a graph showing the relationship between the reception frequency and the interference frequency.

Further, in the above embodiment, one VCO is used and the bands 1 and 2 are also used, but the same can be carried out even if these are provided separately.

[0030]

Since the present invention has the above-mentioned structure, the band of the local oscillation frequency can be narrowed, the structure of the VCO and the mixer can be simplified, and the prescaler IC need not have a wide band. An inexpensive and economical circuit can be provided.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory diagram of the present invention, and is a graph showing a relationship between a reception frequency and an interference frequency.

FIG. 3 is a block diagram of a general BS tuner.

FIG. 4 is a diagram showing an example of frequency arrangement of satellite broadcasting.

FIG. 5 is a diagram showing an example of channel arrangement for satellite broadcasting.

FIG. 6 is a block diagram of an HNB and V polarization simultaneous reception type LNB.

7 is an explanatory diagram of the operation of FIG.

FIG. 8 is a block diagram of a conventional example.

[Explanation of symbols]

 100, 107 Changeover switch 101 LPF 102 HPF 105, 106 Tracking filter 108 Mixer 109 VCO 110 PLL Channel selection circuit

Claims (1)

[Claims] 1. A VCO whose local oscillation frequency is controlled by a PLL tuning circuit, and a mixer which mixes a local oscillation signal from the VCO with a reception signal to be selected and outputs an intermediate frequency signal. In the provided reception tuner, the above V
The frequency of the difference between the local oscillation frequency of the local oscillation signal from the CO and the intermediate frequency of the intermediate frequency signal is the first frequency of the received signal.
A first band setting means for setting a first band to be a channel selection frequency of, and a second frequency of a sum of the local oscillation frequency and the intermediate frequency as a second channel selection frequency of a received signal.
And a second band setting means for setting the band of 1.