Automatic receiving channel setting method of a receiver

#This invention relates to an automatic setting method of a receiving channel of a receiver wherein a television (TV) broadcast through ground waves and a CATV (cable television) broadcast through wire search channels according to each channel plan to store in a memory device.

#Heretofore, since channel plans for TV broadcast through ground waves and CATV broadcasts are different in both transmission passages (in the case of ground waves the broadcast is space, while CATV uses an exclusive cable), each channel in the same frequency zone was allotted to overlap. Further, with CATV broadcasts, many channels are allotted to frequency zones which are not used for ground wave broadcasts.

#FIG. 5 is a block drawing which shows a setting method of receiving channels of a traditional receiver. In the Figure, numeral 1 is a television antenna for receiving a television broadcast wave of a ground wave, 2 is a distributor, 3 is a cable connecting terminal and 4 is a receiver input terminal. The numeral 7 is a signal processing portion where the frequency conversion is conducted against the received signal, 8 is a channel selecting portion where a desired signal of the channel frequency from the received signal is selected, and 10 is an intermediate frequency amplification portion which amplifies a signal converted into the intermediate frequency zone in the signal processing portion 7.

#FIG. 1 is a block drawing which shows the structure of the automatic receiving channel setting method of the receiver according to an embodiment of this invention.

#FIG. 2 is a flow chart which explains the operation of the automatic setting method of the receiving channel according to an embodiment of the first invention.

#FIG. 3 is a flow chart which explains the operation of the automatic receiving channel setting method of the receiver according to the second invention.

#The embodiment of this invention will be described as follows with reference to the drawings. FIG. 1 is a block drawing which shows a structure of the automatic receiving channel setting method of the receiver in the embodiment of FIG. 1. In the Figure, 1 is a TV antenna for receiving the V broadcast of the ground wave, 2 is a distributor, 3 is a connecting terminal for CATV cable, and 4 is a receiver input terminal. The numeral 7 is a signal processing portion which converts the frequency to the receiving signal, 8 is a channel selection portion which selects a desired signal of the channel frequency from the receiving signal, 9 is a switching circuit which switches the receiving mode of the receiver to either the receiving mode of the TV broadcast of the ground wave or the receiving mode of the CATV broadcast, 10 is an intermediate frequency amplification portion where the signal converted to the intermediate frequency zone in the signal processing portion 7 is amplified.

#The numeral 6 is a level detector which detects an output level of the intermediate frequency amplification portion 10, 12 is a ROM (read only memory) which memorizes the channel plans of both TV broadcast of the ground wave and the CATV broadcast, 13 is a RAM (random access memory) which memorizes the results of the channel selection, 5 is a CPU (central processing unit) which controls the channel selection portion 8 and the switching circuit 9 based upon the information from the ROM 12.

#The operation of the hardware is described next. For convenience of description, it is assumed that an exclusive cable of the CATV is connected to the input terminal 4. First, the CPU 5 controls the channel selection portion 8 and the switching circuit 9 according to the diagram and the channel plan memorized in ROM. This output is given to the signal processing portion 7, said processing portion 7 determining the receiving frequency. Then, the CATV signals input to the input terminal 4 of the receivers are selectively received at the signal processing portion 7, then amplified at the intermediate frequency amplification portion 10 and thereafter guided to an image circuit of the TV receiver. A part of the output of the intermediate frequency amplification portion 10 is branched, transferred to the level detector 6 for detecting the level and allotted to return to the CPU 5 after A/D conversion.