Transmission and reception system

In a home bus system control signals and information signals are carried between a transmission station at one location and reception stations at other locations. There are plural signal sources at the transmitting station and plural types of signal formats, such as monaural and stereo or NTSC and HDS. A request signal sent from a receiving station identifies the signal source to be accessed and the signal format capability of a receiver at the receiver station. The request signal is decoded at the transmission station and causes transmission of an information signal from the selected signal source in the identified signal format.

BACKGROUND OF THE INVENTION 
The present invention relates to a transmission and reception system, and 
particularly relates to a transmission and reception system for performing 
transmission and reception of various types of signals through a 
transmission line. 
A home bus system (hereinafter abbreviated to "HBS"), which is about to be 
put into practice, is a system in which carrier frequencies modulated with 
predetermined control signals are transmitted through a transmission line 
to remote locations where the modulated signals are supplied to controlled 
appliances, such as lighting fixtures or the like, provided inside a home 
so as to perform predetermined control of the controlled appliances by 
demodulating the modulated signals. 
An HBS of this type is applicable to a system for transmitting and 
receiving information signals, such as an audio signal, a video signal, or 
the like, wherein, for example, an audio signal transmitting means is 
provided at one location, and a receiving means for receiving the audio 
signal is provided at another location. 
In the case where the transmitted audio signal is a stereo signal and the 
receiving means has only a monaural capability, the system will not 
operate properly. The same is true of the reverse situation, and for that 
matter, it is true in any case where the signal type transmitted differs 
from the signal type for which the receiver is adapted. 
In the case where the transmitting means is a television signal 
transmitting means which can transmit an HD television signal and the 
receiving means is a television receiver which can receive only an NTSC 
signal, it is impossible to receive the transmitted television signal by 
the receiving means because the television signal supplied to the receiver 
through a transmission line is an HD television signal. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to solve the foregoing 
problems in the prior art. 
It is another object of the present invention to provide a transmission and 
reception system by which it is possible to supply a receiving means 
through a transmission line with an information signal which can be 
received by the receiving means. 
In order to attain the foregoing objects, according to an aspect of the 
present invention, the transmission and reception system in which an 
information signal from a transmitting means provided at a first location 
is transmitted through a transmission line so as to be received by a 
receiving means provided at a second location, comprises: a transmission 
request signal output means provided at the second location for coding a 
transmission request signal and for sending out the coded transmission 
request signal onto the transmission line; a decoding means provided at 
the first location for receiving and decoding the transmission request 
signal; and an information signal output control means for causing the 
transmitting means to output an information signal corresponding to the 
output of the decoding means and receivable by the receiving means.

DETAILED DESCRIPTION OF THE INVENTION 
First, referring to FIG. 1, the basic configuration of the transmission and 
reception system according to the present invention will be described 
hereunder. As shown in FIG. 1, the transmission and reception system in 
which an information signal from a transmitting means 1 provided at a 
first location is transmitted through a transmission line so as to be 
received by a receiving means 2 provided at a second location, comprises: 
a transmission request signal output means 3 provided at said second 
location for coding a transmission request signal and for sending out the 
coded transmission request signal onto the transmission line; a decoding 
means 4 provided at the first location for receiving and decoding the 
transmission request signal: and an information signal output control 
means 5 for causing the transmitting means to output an information signal 
compatible with the reception capability of the receiving means. 
In the above-mentioned configuration, a transmission request signal is 
supplied from the transmission request signal output means 3 to the 
decoding means 4 through the transmission line 1. This transmission 
request signal is decoded in the decoding means 4, and the decoded output 
of the decoding means 4 is supplied to the information signal output 
control means 5. On the basis of the decoded output of the decoding means 
4, the control means 5 causes the transmitting means 1 to output an 
information signal to the transmission line 1. At this time, the control 
means 5 controls the transmitting means 1 to cause the transmitting means 
1 to output an information signal receivable by the receiving means 2. 
The above-mentioned transmission request signal may include data for 
identifying a format or type of information signal receivable by the 
receiving means 2. The decoding means 4 decodes this identification data 
so that the transmitting means 1 is controlled by the control means 5 so 
as to output the above-mentioned receivable information signal. 
Alternatively, the transmission request signal may include data for 
identifying the receiving means 2. In this case, the decoding means 4 
decodes this identification data, and the decoded output of the decoding 
means 4 is put into the control means 5. In response to this decoded 
signal, the control means 5 controls the transmitting means 1 to output an 
information signal receivable by the receiving means 2 onto the 
transmission line 1. 
FIG. 2 shows an embodiment of the system for performing transmission and 
reception of an audio signal. In FIG. 2, a plurality of signal output 
units 6 such as a CD (compact disc) player, a tape deck, a tuner, and so 
on, are provided in a room A, and one of the signal output units 6 is 
selected by a function switch SW.sub.1. Left and right stereo audio 
signals S.sub.L and S.sub.R supplied from the selected one of the signal 
output units 6 are supplied to modulators 7.sub.L and 7.sub.R, 
respectively, in which carrier frequencies f.sub.1 and f.sub.2, different 
from each other, are modulated with the stereo audio signals S.sub.L and 
S.sub.R, respectively. 
On the other hand, the stereo audio signals S.sub.L and S.sub.R are added 
together by an adder 8 so that a monaural signal S.sub.M is outputted from 
the adder 8. The monaural signal S.sub.M is supplied to a modulator 
7.sub.M, in which another carrier of a frequency f.sub.3, different from 
the above-mentioned frequencies f.sub.1 and f.sub.2, is modulated with 
this monaural signal S.sub.M. 
ln the room A, a controller 9 for controlling the modulators 7.sub.L, 
7.sub.R and 7.sub.M is provided in addition to the signal output units 6 
and the function switch SW.sub.1. 
In a room B, which is located separately from room A, demodulators 10.sub.L 
and 10.sub.R for demodulating the carriers f.sub.1 and f.sub.2 are 
provided so that demodulated signals therefrom, that is, the 
above-mentioned stereo audio signals S.sub.L and S.sub.R, are supplied to 
amplifiers 11.sub.L and 11.sub.R, respectively. The signals amplified by 
amplifiers 11.sub.L and 11.sub.R are supplied to a pair of speakers 
SP.sub.L and SP.sub.R, respectively, so that a stereo signal is radiated 
from speakers SP.sub.L and SP.sub.R. Additionally, a controller 12 is 
provided in the room B. 
Further, in a room C, a demodulator 11.sub.M for demodulating the modulated 
carrier f.sub.3, and the demodulated output signal of the demodulator 
11.sub.M, that is, the monaural audio signal S.sub.M, is supplied to an 
amplifier 11.sub.M. The signal amplified by the amplifier 11.sub.M is 
supplied to a speaker SP.sub.M so that a monaural signal is radiated from 
the speaker SP.sub.M. Additionally, a controller 13 is provided in the 
room C. 
The modulated carriers f.sub.1, f.sub.2 and f.sub.3 are put out from the 
modulators 7.sub.L, 7.sub.R and 7.sub.M onto a transmission line 1.sub.1, 
such as a coaxial cable or the like, so that those carriers f.sub.1, 
f.sub.2 and f.sub.3 are supplied to the demodulators 10.sub.L, 10.sub.R 
and 10.sub.M through the transmission line 1.sub.1. 
A transmission request signal is put out from each of the controllers 12 
and 13 in the rooms B and C, and supplied to the controller 9 in the room 
A through a transmission line 1.sub.1. Each of the controllers 12 and 13, 
as shown in FIG. 3 has a CPU 14, an output unit selecting switch SW.sub.2, 
and a transmission switch SW.sub.3, the switches SW.sub.2 and SW.sub.3 
being connected to the CPU 14. An internal memory of the CPU 14 of the 
controller 12 provided in the room B stores stereo signal identifying 
data, and an internal memory of the CPU 14 of the controller 13 provided 
in the room C stores monaural signal identifying data. On the other hand, 
the controller 9 provided in the room A, as shown in FIG. 4, has a CPU 15 
for decoding the transmission request signals respectively generated from 
the controllers 12 and 13 and for supplying control signals to the signal 
output units 6, the function switch SW.sub.1, and the modulators 7.sub.L, 
7.sub.R and 7.sub.M. 
In the above-mentioned configuration, the operations executed by the CPUs 
14 and 15 will be described with reference to the flow charts of FIG. 5. 
First, the CPU 14 judges, in its first step S1, whether the output unit 
selecting switch SW.sub.2 has been operated or not. If the switch SW.sub.2 
has been operated and hence the judgment shows "YES", the process of the 
CPU 14 is shifted into a step S2 in which the CPU 14 sets in its registers 
data for identifying the selected one of the signal output units 6 and 
data stored in its internal memory for identifying a stereo or monaural 
signal. Next, the process is shifted to a step S3 in which the CPU 14 
judges whether the transmission switch SW.sub.3 has been operated or not. 
If the switch SW.sub.3 has been operated and hence the judgment shows 
"YES", the process is shifted to a step S4 in which the CPU 14 supplies 
the transmission line 1.sub.2 with a transmission request signal including 
the signal output unit identification data and stereo/monaural 
identification data set in the above-mentioned registers. 
Next, the operation of the CPU 15 will be described. First, the CPU 15 
judges whether the above-mentioned transmission request signal has been 
received or not in a step S11, and if the transmission request signal has 
been received and hence the judgment shows "YES", the process of the CPU 
15 is shifted to a step S12 in which the CPU 15 decodes the received 
transmission request signal. Next, in a step S13, the CPU 15 supplies 
control signals to the selected signal output unit 6 and the function 
switch SW.sub.1 on the basis of the data for identifying the signal output 
unit. By the control signals, the selected signal output unit 6 is 
actuated, and at the same time, the function switch SW.sub.1 is changed 
over so that the output of the selected signal output unit 6 can pass 
through the function switch SW.sub.1. 
Next, the process of the CPU 15 is shifted to a step S.sub.14 in which the 
CPU 15 outputs a control signal to the modulators 7.sub.L, 7.sub.R and 
7.sub.M on the basis of the stereo/monaural identification data. If the 
control signal generated is in response to data for identifying a stereo 
signal, the modulators 7.sub.L and 7.sub.R are driven so as to modulate 
the carriers f.sub.1 and f.sub.2 with the stereo signals S.sub.L and 
S.sub.R and supply those modulated carrier signals onto the transmission 
line 1.sub.1. As a result, in the room B, the demodulators 10.sub.L and 
10.sub.R demodulate the carrier signals f.sub.1 and f.sub.2 so that the 
stereo signals S.sub.L and S.sub.R supplied from the selected signal 
output unit 6 can be listened to from the speakers SP.sub.L and SP.sub.R 
after passing through the amplifiers 11.sub.L and 11.sub.R. On the 
contrary, if the control signal generated is in response to data for 
identifying a monaural signal, the modulator 7.sub.M is driven so as to 
modulate the carrier f.sub.3 with the monaural signal S.sub.M from the 
adder 8 and to supply this modulated carrier signal onto the transmission 
line 1.sub.1. As a result, in the room C, the demodulator 10.sub.M 
demodulates the modulated carrier signal f.sub.3 so that the monaural 
signal S.sub.M supplied from the above-mentioned adder 8 can be listened 
to from the speaker SP.sub.M after passing through the amplifier 11.sub.M. 
In the case where each room has only the capability for responding to a 
single type of signal, such as in the above case where room B has 
receivers for only stereo and room C has receivers for only monaural, the 
i.d. signal that is selected by the CPU 14 to control selection of the 
type of signal transmitted may be a room i.d. signal. An example of this 
is provided in the flow charts of FIG. 6. 
First, the CPU 14 judges, in step S21, whether the output unit selecting 
switch SW.sub.2 has been operated or not. If the switch SW.sub.2 has been 
operated and hence the judgment shows "YES", the process of the CPU 14 is 
shifted into a step S22 in which the CPU 14 sets in its registers data for 
identifying the selected one of the signal output units 6 and data stored 
in its internal memory for identifying the room B or C. Next, the process 
is shifted to a step S23 in which the CPU 14 judges whether the 
transmission switch SW.sub.3 has been operated or not. If the switch 
SW.sub.3 has been operated and hence the judgment shows "YES", the process 
is shifted to a step S24 in which the CPU 14 supplies the transmission 
line 1.sub.2 with a transmission request signal including the signal 
output unit identification data and room B/C identification data set in 
the above-mentioned registers. 
Next, the operation of the CPU 15 will be described. First, the CPU 15 
judges whether the above-mentioned transmission request signal has been 
received or not in a step S31, and if the transmission request signal has 
been received and hence the judgment shows "YES", the process of the CPU 
15 is shifted to a step S32 in which the CPU 15 decodes the received 
transmission request signal. Next, in a step S33, the CPU 15 supplies 
control signals to the selected signal output unit 6 and the function 
switch SW.sub.1 on the basis of the data for identifying the signal output 
unit. By the control signals, the selected signal output unit 6 is 
actuated, and at the same time, the function switch SW.sub.1 is changed 
over so that the output of the selected signal output unit 6 can pass 
through the function switch SW.sub.1. Next, the process of the CPU 15 is 
shifted to a step S34 in which the CPU 15 outputs a control signal to the 
modulators 7.sub.L, 7.sub.R and 7.sub.M on the basis of the room B/C 
identification data. 
If the control signal generated is in response to data for identifying the 
room B, the modulators 7.sub.L and 7.sub.R are driven so as to modulate 
the carriers f.sub.1 and f.sub.2 with the stereo signals S.sub.L and 
S.sub.R and to supply those modulated carrier signals onto the 
transmission line 1.sub.1. As a result, in the room B, the demodulators 
10.sub.L and 10.sub.R demodulate the carrier signals f.sub.1 and f.sub.2 
so that the stereo signals S.sub.L and S.sub.R supplied from the selected 
signal output unit 6 can be listened to from the speakers SP.sub.L and 
SP.sub.R after passing through the amplifiers 11.sub.L and 11.sub.R. 
On the contrary, if the control signal generated is in response to data for 
identifying the room C, the modulator 7.sub.M is driven so as to modulate 
the carrier f.sub.3 with the monaural signals S.sub.M from the adder 8 and 
to supply this modulated carrier signal onto the transmission line 
1.sub.1. As a result, in the room C, the demodulator 10.sub.M demodulates 
the modulated carrier signal f.sub.3 so that the monaural signal S.sub.M 
supplied from the above-mentioned adder 8 can be listened to from the 
speaker SP.sub.M after passing through the amplifier 11.sub.M. 
In the above-mentioned embodiments, each of the transmission request 
signals generated from the respective controllers 12 and 13 may include 
data for identifying the room A, or data for identifying the controller 2, 
so that the above-mentioned transmission request signals are accessed only 
by the controller 2 in the room A so as to be decoded therein. 
Moreover, the carrier frequency f.sub.3 of the monaural signal S.sub.M may 
be the same as the carrier frequency f.sub.1 or f.sub.2 of the stereo 
signal S.sub.L or S.sub.R, and further the transmission lines 1.sub.1 and 
1.sub.2 may be made a single transmission line through which both audio 
and transmission request signals can be transmitted. 
Further, in addition to transmission control of stereo/monaural signals, 
the present invention is applicable to transmission control of 
color/black-and-white televisions, transmission control of 
Hi-Fi-audio/telephone signals transmission control of NTSC/HD television 
signals, and so on. For example, if a receiving side has a television 
receiver for receiving only an NTSC television signal in the case of 
transmission control of NTSC/HD TV signals, and when a transmission 
request signal is sent from the receiving side in question, an HD 
television signal is converted into an NTSC television signal on the 
transmitting side so that the converted NTSC television signal is 
transmitted to the receiving side. 
As has been described above, according to the present invention, upon 
generation of a transmission request from a receiving means, a 
transmitting means can transmit to the receiving means an information 
signal receivable by the receiving means through a transmission line. It 
is therefore possible to perform optimum reception, and at the same time 
it is possible to provide effective use of a transmission line.