Television – Receiver circuitry – Tuning
Reexamination Certificate
1999-03-23
2001-06-26
Eisenzopf, Reinhard J. (Department: 2614)
Television
Receiver circuitry
Tuning
C348S731000, C348S735000, C348S732000, C348S733000, C455S186100, C455S185100, C455S184100, C455S193100, C455S164100, C455S192200
Reexamination Certificate
active
06252635
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a broadcast receiver comprising a tuner for tuning the receiver to a desired station in response to an applied tuning frequency, control means for reading said tuning frequency from a user-selected one of a plurality of memory locations in which such tuning frequencies are stored, means for receiving and decoding a list of nominal tuning frequencies identifying receivable broadcast stations and for storing said nominal tuning frequencies in respective locations of said memory. The invention also relates particularly but not exclusively to a television receiver.
The invention further relates to a method of tuning a broadcast receiver comprising the steps of reading a tuning frequency from a user-selected one of a plurality of memory locations in which such tuning frequencies are stored, and applying said tuning frequency to a tuner; and receiving a list of nominal tuning frequencies identifying receivable broadcast stations and storing said nominal tuning frequencies in respective locations of said memory.
2. Description of the Related Art
Television receivers have a frequency synthesis tuning arrangement for tuning the television receiver to a desired television station. In such an arrangement, a digital representation of the station transmission frequency is normally applied to the television tuner. This digital representation of a transmission frequency is herein further referred to as the tuning frequency. The tuning frequency is applied to the tuner by a control circuit, usually a microprocessor, in response to a channel selection made by the user.
To avoid the necessity for the user to enter difficult-to-remember transmission frequencies or channel numbers, television receivers normally allow the user to select channels by entering program numbers. In such receivers, the tuning frequencies to be applied to the tuner are stored in a tuning memory which is addressed by the program numbers assigned to the television stations.
A problem of such a television receiver is assigning the program numbers to the television stations which can be received in a given terrestrial or cable network. The initial programming of the tuning memory installation is usually referred to as channel installation.
A solution to this problem is disclosed in Applicant's U.S. Pat. No. 4,894,714. In accordance with this prior-art method, a list of nominal tuning frequencies or channel numbers of the receivable broadcast stations is transmitted by the (cable) network provider. Such a list is hereinafter referred to as channel list. In practical embodiments, the channel list is transmitted along with at least one of the broadcast television programs, e.g., as a cyclically transmitted teletext page. Upon installing the television receiver, the channel list is captured, decoded and stored in the tuning memory of the receiver without requiring any further user intervention. Thereafter, the various stations are accessible through the program numbers defined by the network provider in accordance with local habits.
SUMMARY OF THE INVENTION
It is an object of the invention to further improve the automatic channel installation process.
To this end, a first aspect of the invention provides a broadcast receiver as described above, characterized in that said control means are further arranged to determine whether a station is received upon applying the nominal frequency to the tuner and, if said determination is negative, to modify said tuning frequency within a predetermined range until a station is found and store the modified tuning frequency in the same memory location. A second aspect of the invention provides a method of tuning a broadcast receiver as described above, characterized in that the method comprises the step of determining whether a station is received upon applying the nominal tuning frequency to the tuner and, if said determination is negative, modifying said tuning frequency within a predetermined range until a station is found and storing the modified tuning frequency in the same memory location.
The invention is based on the observation of a problem occurring in cable networks with one or more subscription channels (channels that can only be viewed after decoding/descrambling). To receive such a subscription channel, a set-top box with a descrambler and an RF modulator is provided. The television receiver can only reproduce the program when the relevant RF channel is also “installed”. To assist the subscriber (user) in carrying out said installation, the networks convey the RF frequency of the set-top box in the channel list as well, thereby assuming that all set-top boxes have the same RF frequency. However, the RF frequencies of the set-top boxes cannot be adjusted as precisely as those of professional transmitter stations. Consequently, the automatic installation of the subscription channel often fails. Instead of reproducing the descrambled signal when the subscription channel is selected, the television receiver is often incorrectly tuned and enters a mute mode. This leads to many complaints to the subscription channel provider.
The invention provides a solution to this problem by determining whether a station is indeed received upon tuning to the channel which is programmed in the tuning memory. If this is not the case, for example, because the tuning circuit fails to detect a carrier and/or a video synchronizing signal, the tuning frequency applied to the tuner is reduced by, say, a quarter of a TV channel bandwidth and then slightly incremented until a TV signal is detected. The tuning frequency applied to the tuner at that moment is then stored in the tuning memory. Subsequently, the television receiver will be correctly tuned when the stored tuning frequency is recalled. This “post-installing” process can be automatically carried out for each channel in the channel list after a regular installation procedure or at any convenient time upon a user request. Instead of lowering the tuning frequency, it is also possible to increase the tuning frequency and thereafter slightly decrease it until a TV signal is detected.
An embodiment in accordance with the invention comprises the broadcast receiver being a television receiver and the predetermined range extending from fn−4 MHz to fn+4 MHz, in which fn is the nominal tuning frequency.
Care should be taken not to lower or increase the tuning frequency to such a value that another tuning frequency (other channel, etc.) is found.
An embodiment in accordance with the invention comprises said step of modifying a nominal tuning frequency being carried out for each stored tuning frequency after receiving and storing the nominal frequencies.
The method can be performed for all (other) channels as a further fine tuning method.
The invention and additional features which may be optionally used to implement the invention to advantage are apparent from and will be elucidated with reference to the examples described hereinafter and shown in the FIGURE.
REFERENCES:
patent: 4894714 (1990-01-01), Christis
patent: 4908707 (1990-03-01), Kinghorn
patent: 5038211 (1991-08-01), Hallenbeck
patent: 5253066 (1993-10-01), Vogel
patent: 5579061 (1996-11-01), Vaske
patent: 5732338 (1998-03-01), Schwob
patent: 6025887 (2000-02-01), Vaske
patent: 6144843 (2000-11-01), Kianush et al.
Eisenzopf Reinhard J.
Goodman Edward W.
Natnael Paulos
U.S. Philips Corporation
LandOfFree
Automatic tuning frequency or channel number installation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic tuning frequency or channel number installation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic tuning frequency or channel number installation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2529568