Satellite broadcasting tuner

A satellite broadcasting tuner with which satellite broadcasting of any channel can be enjoyed only by a channel selecting operation thereof whether or not broadcasting of the channel involves special signal processing. The tuner includes external input terminals for receiving video and aural signals from an external decoding apparatus, a changing over circuit for alternatively coupling video and aural signals from the external input terminals or video and aural signals from a signal processing circuit, which extracts such video and aural signals from an output of a demodulating circuit for a received satellite broadcasting signal, to external output terminals of the tuner to which an external monitor apparatus is connected, a memory for storing therein channels of satellite broadcasting which is broadcast in a specially processed signal form, and a controller for controlling the changing over circuit to couple, when one of the channels stored in the memory is to be received, the external decoding apparatus to the external monitor apparatus.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a satellite broadcasting tuner. 
2. Description of the Prior Art 
As a pay system is employed for reception of satellite broadcasting, 
broadcasting of a video signal in a scrambled condition is employed by 
some satellite broadcasting channels. If broadcasting in a scrambled 
condition is employed by a channel, then mere reception of broadcasting of 
the channel by way of a satellite broadcasting tuner will not allow a 
video image to be displayed on a monitor screen. 
In order to permit broadcasting which involves such special signal 
processing to be enjoyed, a receiver system must necessarily have such 
construction as shown in FIG. 3. In particular, referring to FIG. 3, a 
receiver system must be constructed not only such that a video signal and 
left (L) and right (R) aural signals demodulated by and outputted from a 
satellite broadcasting tuner 1 are supplied directly to a monitor 
apparatus 2 as in a conventional system, but also such that, in order to 
cope with broadcasting which involves scrambling processing, a signal 
demodulated by the satellite broadcasting tuner 1 is supplied once to a 
decoder unit or de-scrambler 3 to de-scramble the same and output signals 
of the de-scrambler 3 (video signal and L and R aural signals) are 
supplied to the monitor apparatus 2. In short, broadcasting of a channel 
which involves scrambling processing cannot be enjoyed without such 
de-scrambler 3, and accordingly, a receiver system requires two signal 
input systems to a monitor apparatus 2. 
It is to be noted that reference numeral 4 in FIG. 3 denotes a satellite 
broadcasting antenna, and 5 a satellite broadcasting converter. 
By the way, where a receiver system is constructed to cope with scrambled 
broadcasting in this manner, if scrambled broadcasting is performed with a 
particular channel, then the monitor apparatus 2 must have two input modes 
or input terminals for reception of satellite broadcasting of the 
particular channel and for reception of satellite broadcasting of any 
other channel which does not involve scrambling processing. 
In short, for ordinary satellite broadcasting, a circuit system of the 
monitor apparatus 2 must be connected so that a signal may be supplied 
thereto by way of an external input terminal section T.sub.1, but for 
scrambled satellite broadcasting, the circuit system must be connected so 
that a signal may be supplied by way of the other external input terminal 
section T.sub.2. 
Accordingly, when it is tried to change over a receiving channel, for 
example, from an ordinary satellite broadcasting channel to the scrambled 
satellite broadcasting channel, an operation of changing over the input 
mode of the monitor apparatus 2 must be performed together with a channel 
changing over operation. 
Consequently, such problem takes place that a satellite broadcasting 
channel selecting operation is so complicated that a channel changing over 
operation cannot be performed particularly by a user who is unfamiliar 
with such apparatus or does not recognize an input mode of the monitor 
apparatus 2. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a satellite 
broadcasting tuner with which satellite broadcasting of any channel can be 
enjoyed only by a channel selecting operation thereof whether or not 
broadcasting of the channel involves special signal processing. 
In order to attain the object, according to the present invention, there is 
provided a satellite broadcasting tuner which comprises demodulating means 
for demodulating a received satellite broadcasting signal, signal 
processing means for extracting a video signal and an aural signal from an 
output of the demodulating means, first external output terminal means for 
outputting a video signal and an aural signal from the signal processing 
means to an external apparatus, second external output terminal means for 
outputting a demodulation output of the demodulating means to an external 
decoding apparatus, external input terminal means for receiving a video 
signal and an aural signal from the external decoding apparatus connected 
to the second external output terminal means, changing over means for 
alternatively coupling a video signal and an aural signal from the 
external input terminal means or a video signal and an aural signal from 
the signal processing means of the first external output terminal means, 
storage means for storing therein a channel or channels of satellite 
broadcasting which is broadcast in a specially processed signal form, 
means for selectively designating a channel of satellite broadcasting, and 
controlling means for judging whether or not a channel designated by the 
designating means is the channel or one of the channels stored in the 
storage means and for controlling the changing over means to alternatively 
couple a video signal and an aural signal supplied from the external 
decoding apparatus by way of the external input terminal means to the 
first external output terminal means when the designated channel is the 
channel or one of the channels stored in the storage means. The storage 
means may be a ROM in which a channel or channels of satellite 
broadcasting which is broadcast in a specially processed signal form are 
stored in advance. 
In the satellite broadcasting tuner, a satellite broadcasting channel or 
channels of satellite broadcasting which is broadcast in a specially 
processed signal form such as a scrambled signal form are stored in the 
storage means. Then, when a satellite broadcasting channel designated by 
the designating means is the channel or one of the channels stored in the 
storage means, the changing over means is changed over to a condition 
wherein a video signal and an aural signal received by way of the external 
input terminal means from an external decoding apparatus connected to the 
second external output terminal means are coupled to the first external 
output terminal means to which such an external apparatus as a monitor 
apparatus is connected. Consequently, whether a satellite broadcasting a 
user wants to enjoy is broadcast in a specially processed signal form or 
not, a satellite broadcasting channel selecting operation is not 
complicated nor difficult but can be performed by a simple operation of a 
channel button or the like. Further, only one input signal system is 
required to be connected to such monitor apparatus. Accordingly, a user 
who may be unfamiliar with a satellite broadcasting tuner need not be 
aware of an input mode to the monitor apparatus upon channel selecting 
operation. 
The above and other objects, features and advantages of the present 
invention will become apparent from the following description and the 
appended claims, taken in conjunction with the accompanying drawings in 
which like parts or elements are denoted by like reference characters.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, there is shown a receiver system in which a satellite 
broadcasting tuner according to the present invention is incorporated. The 
receiver system includes, similarly to the conventional receiver system 
described hereinabove with reference to FIG. 3, a satellite broadcasting 
tuner 10, a monitor apparatus 2 and a decoder unit or de-scrambler 3. The 
satellite broadcasting tuner 10 is constructed in accordance with the 
present invention. 
In the receiver system, radio waves of a 12 GHz band received at a 
satellite broadcasting antenna 4 are converted into a signal of a first 
intermediate frequency (1.03-1.33 GHz) by a satellite broadcasting 
converter 5 and then inputted to the satellite broadcasting tuner 10 by 
way of a coaxial table 6. 
The satellite broadcasting tuner 10 includes a second intermediate 
frequency converting circuit section 11 which selects a desired channel 
from within received signals of first frequencies supplied thereto from 
the satellite broadcasting converter 5. A signal of the thus selected 
channel is converted into another signal of a second intermediate 
frequency of 134.26 MHz or 402.78 MHz. The signal of the second 
intermediate frequency is supplied to an FM demodulating circuit section 
12, at which it is once processed for amplitude limiting or the like and 
then FM demodulated. 
The thus FM demodulated signal S.sub.DET is supplied to an aural signal 
processing circuit 13 consisting of a 4-phase DPSK demodulating circuit 
and a PCM demodulating circuit in a known manner to obtain L and R aural 
signals. The FM demodulated signal S.sub.DET is also supplied to a video 
signal processing circuit 14 consisting of a de-emphasis circuit, an 
energy dispersal signal removing circuit, a video amplifier circuit and so 
forth in a known manner to extract a video signal. The thus extracted L 
and R aural signals and video signal are introduced to an outputting 
section 16 by way of contacts b of a changing over circuit 15 so that they 
are supplied to the monitor apparatus 2 by way of wires connected between 
the outputting section 16 of the satellite broadcasting tuner 10 and an 
input terminal section T.sub.1 of the monitor apparatus 2. 
In order to cope with scrambled broadcasting signals, an output terminal 
section 17 for a detection output S.sub.DET outputted from the FM 
demodulating circuit section 12 and digital control data (bit stream) 
b.sub.st outputted from the aural signal processing circuit 13 is provided 
for the satellite broadcasting tuner 10 and connected to the de-scrambler 
3. Thus, when scrambled broadcasting is to be enjoyed, control data 
b.sub.st for de-scrambling processing and a detection output S.sub.DET are 
supplied to the de-scrambler 3, at which scrambled signals are decoded 
into original video signal V and L and R aural signals. 
The satellite broadcasting tuner 10 further includes an external input 
terminal section 18 by way of which a video signal V and L and R aural 
signals outputted from the de-scrambler 3 are inputted to the satellite 
broadcasting tuner 10. Signals inputted by way of the external input 
terminal section 18 are supplied to contacts a of the changing over 
circuit 15. 
The satellite broadcasting tuner 10 further includes a system controller or 
CPU (central processing unit) 19 which controls a channel selecting 
operation, various signal processing operations and a changing over 
operation between the contacts a and b of the changing over circuit 15 in 
accordance with an operation of a user and a control program transmitted 
by way of a control bus B. Data for such control and the control program 
are stored in a ROM (read only memory) 20 or a RAM (random access memory) 
21. 
The satellite broadcasting tuner 10 further includes an infrared rays 
receiving section 22 for detecting a command signal which is outputted 
from a remote commander RC in response to a manual operation of the remote 
commander RC. An infrared rays command signal thus detected is amplified 
as an electric signal and converted into a digital code by an operating 
signal generating section 23 and then inputted to the CPU 19 by way of the 
control bus B. It is to be noted that, also when a panel button or buttons 
provided on an outer casing not shown of the satellite broadcasting tuner 
10 are operated, corresponding operation information is supplied to the 
CPU 19 similarly. 
In the satellite broadcasting tuner 10 having such construction as 
described above, changing over between the contacts a and b of the 
changing over circuit 15 must be performed between when ordinary satellite 
broadcasting is to be enjoyed and when scrambled satellite broadcasting is 
to be enjoyed. 
The satellite broadcasting tuner 10 operates in the following manner to 
cope with such circumstances. 
First, as initialization before use of the receiver system, a channel in 
which scrambled broadcasting is performed will be registered into the RAM 
21 in response to an operation of a user or the like. 
For example, if the third and eleventh channels of satellite broadcasting 
are broadcast in scrambled conditions, then data of "BS-3" and "BS-11" are 
written into a predetermined address of the RAM 21. 
After execution of such registration, if a satellite broadcasting changing 
over command is inputted, for example, from the remote commander RC, then 
the CPU 19 executes such control as illustrated by a flow chart of FIG. 2. 
Referring to FIG. 2, after a satellite broadcasting channel command is 
developed from the remote commander RC and inputted to the CPU 19 at step 
F100, it is judged first at step F101 whether or not the satellite 
broadcasting channel is one of the registered channels. If the inputted 
satellite broadcasting channel is not any registered channel, then the CPU 
19 controls the changing over circuit 15 to connect the switches thereof 
to the contacts b at step F102, and then controls, at step F104, the 
second intermediate frequency changing over circuit section 11 to select 
the channel corresponding to the manual operation of the remote commander 
RC. 
However, in case it is judged at step F101 otherwise that the channel 
corresponding to such manual operation is one of the satellite 
broadcasting channels (that is, scrambled broadcasting channels) 
registered in the RAM 21, the CPU 19 controls the changing over circuit 15 
to connect the switches thereof to the contacts a at step F103, whereafter 
it controls, at step F104, the second intermediate frequency changing over 
circuit section 11 to select the channel corresponding to the manual 
operation. 
As the CPU 19 executes such control as described above, a user of the 
receiver system can enjoy broadcasting of any satellite broadcasting 
channel only by a simple channel selecting operation (an operation of a 
channel up/down button or an operation of a direct channel selecting 
button) whether or not the broadcasting is scrambled broadcasting. For 
example, when the channel selection is to be changed over from a BS 7 
channel to the BS 11 channel of scrambled broadcasting or when the channel 
selection is to be changed over from the BS 11 channel to a further BS 15 
channel of non-scrambled broadcasting, an input mode changing over 
operation for the monitor apparatus 2 is unnecessary. Accordingly, even an 
unfamiliar user will not be bewildered with the operation. 
By the way, in case all channels of scrambled broadcasting are known in 
advance, such information may be registered in the ROM 20 of the satellite 
broadcasting tuner 10 in advance upon manufacture. 
It is to be noted that, while the satellite broadcasting tuner in the 
embodiment described above is described incorporated in a receiver system 
adapted to receive scrambled broadcasting, a satellite broadcasting tuner 
according to the present invention can exhibit similar effects even where 
it is applied to a receiver system of broadcasting which involves any 
other special manner of signal processing. For example, while a receiver 
system adapted to receive broadcasting of the MUSE system requires a MUSE 
decoder (or, in some cases, a MUSE-NTSC converter), an input mode changing 
over operation for the monitor apparatus 2 is unnecessary also with such 
receiver system if an output of such MUSE decoder is received by way of 
the external input terminal section 13 and a changing over operation of 
the changing over circuit 15 is performed automatically in accordance with 
registered channels. 
Having now fully described the invention, it will be apparent to one of 
ordinary skill in the art that many changes and modifications can be made 
thereto without departing from the spirit and scope of the invention as 
set forth herein.