Method and apparatus for determining channel to which a TV or VCR is tuned
First Claim
Patent Images
1. A return loss channel detector apparatus comprising:
- a directional coupler having an RF output for coupling to the RF input of an analog television or analog video tape recorder (hereafter TVR) and having a transmit input for receiving probe signals and a transmit output at which appears probe signals reflected from said TVR;
a multiplexer having an output coupled to said transmit input and having a first input for receiving a radio frequency carrier having a video signal modulated thereon and having a second input for receiving probe signals;
a transmitter for generating probe signals; and
a receiver for receiving reflected probe signals and calculating a return loss ratio therefrom.
7 Assignments
0 Petitions
Accused Products
Abstract
Method and apparatus to determine the channel to which a TV tuner is tuned from a return loss ratio measurement circuit in a set top decoder. The method comprises generating a plurality of probe signals having frequencies spread throughut the TV channel band, preferably using harmonics of a zero order hold D/A converter. The return loss ratio of the reflected probe signals is then determined and stored as a signature for the TV channel and the signatures can subsequently be used along with new return loss ratio measurements to determine the TV channel to which a TV or VCR tuner is tuned.
-
Citations
22 Claims
-
1. A return loss channel detector apparatus comprising:
-
a directional coupler having an RF output for coupling to the RF input of an analog television or analog video tape recorder (hereafter TVR) and having a transmit input for receiving probe signals and a transmit output at which appears probe signals reflected from said TVR;
a multiplexer having an output coupled to said transmit input and having a first input for receiving a radio frequency carrier having a video signal modulated thereon and having a second input for receiving probe signals;
a transmitter for generating probe signals; and
a receiver for receiving reflected probe signals and calculating a return loss ratio therefrom. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A process for determining if an analog TV or VCR (hereafter TVR) is tuned to a particular TV channel, comprising the steps:
-
(1) generating one or more probe signals having frequencies within the passband or some of which are within and some of which are without the passband of a tunable bandpass filter within a tuner of a TVR when said TVR is tuned to a particular TV channel;
(2) transmitting said probe signals to an RF tuner input of said TVR and coupling reflected power back to an input of a receiver;
(3) in said receiver calculating a return loss ratio and determining therefrom whether said TVR is tuned to said particular TV channel. - View Dependent Claims (14, 15, 16, 17)
-
-
18. A process for using return loss to verify a TV channel to which a TVR is tuned, comprising the steps:
-
1) detecting a local oscillator leakage signal and counting the frequency thereof and using said frequency to lookup a TV channel to which a TVR is tuned which would cause said local oscillator to have said frequency;
2) generating and transmitting into an RF input of said TVR a plurality of probe signals having frequencies spread through a band of frequencies in which TV channels are transmitted;
3) determining the transmitted power of each probe signal;
4) measuring the reflected power of each probe signal;
5) calculating the return loss ratio for each probe signal;
6) determining the probe signal with the maximum return loss;
7) determine the TV channel whose frequency has the best match with the probe signal which suffered the highest return loss;
8) determining if the TV channel determined in step 7 is the same as the TV channel determined in step 1;
9) if step 8 determines the TV channels are different, use the TV channel determined in step 7 and generate suitable control signals for use by a set top decoder to tune to a downstream channel carrying the TV channel determined in step 7 and recover the data thereof and convert said data to a television signal and modulate an RF carrier having the frequency of the TV channel determined in step 7 with said television signal;
10) if step 8 determines the TV channels are the same, use the TV channel determined in steps 7 and 1 and generate suitable control signals for use by a set top decoder to tune to a downstream channel carrying the TV channel determined in step 7 and recover the data thereof and convert said data to a television signal and modulate an RF carrier having the frequency of the TV channel determined in step 7 with said television signal.
-
-
19. A process for using return loss to determine a TV channel to which a TVR is is tuned, comprising the steps:
-
1) performing a setup process to learn the signature of each TV channel comprised of the return loss ratios of a plurality of probe signals which have frequencies spread throughout the TV channel band, and storing the signature for each TV channel;
2) determing the TV channel to which a TVR is currently tuned by performing the following steps;
3) generating a plurality of probe signals having frequencies which are spread through the band of frequencies in which TV channels are transmitted and transmitting said probe signals into the RF input of a tuner of a TVR;
4) calculating the return loss ratio on each probe signal;
5) comparing the collection of return loss ratios and comparing the collection of return loss ratios to the signature stored in memory for each TV channel and determining the TV channel have the least difference between its signature and said collection of return loss ratios calculated in step 4;
generating suitable control signals to control a set top decoder to tune to a downstream channel carrying the TV channel determined in step 5 and recover the data thereof and convert said data to a television signal and modulate an RF carrier having the frequency of the TV channel determined in step 5 with said television signal.
-
-
20. A setup process for learning the return loss ratio signature of each TV channel comprising steps for:
-
1) establishing the proper infrared protocol for at least channel change commands to be emitted from an infrared transmitter;
2) entering a learning mode;
3) transmitting a channel change command from said infrared transmitter to cause a TVR connected to a set top decoder with a return loss ratio channel detection circuit therein to tune to a specific channel;
4) controlling said return loss ratio channel detection circuit to generate a plurality of probe signals and transmit them into the RF input of a tuner in said TVR;
5) measure the reflected amplitude of each said probe signal and calculate a return loss ratio therefor and store the collection of return loss ratios as a signature for the TV channel to which the TVR is currently tuned;
6) transmitting channel change command from said infrared transmitter to cause said TVR to change to a new channel;
7) repeating steps 4 and 5 for the new channel;
8) repeating steps 6 and 7 until a signature has been learned for every TV channel.
-
-
21. A setup process for learning the return loss ratio signature of each TV channel comprising steps for:
-
1) establishing the proper infrared protocol for at least channel change commands to be emitted from an infrared transmitter in an external remote control for a set top decoder (STB), said external remote control including an RF transmitter for communicating with an RF receiver in said STB, said STB including a return loss ratio channel detection circuit therein having an RF output for coupling to the RF input of a tuner of a TVR;
2) entering a learning mode;
3) transmitting a channel change command from said infrared transmitter in said external remote control to cause said TVR connected to said return loss ratio channel detection circuit to tune to a specific channel, and sending a radio frequency message to said STB telling said STB to which TV channel said TVR has just been tuned;
4) controlling said return loss ratio channel detection circuit to generate a plurality of probe signals and transmit them into said RF input of said tuner in said TVR;
5) measuring the reflected amplitude of each said probe signal and calculate a return loss ratio therefor and store the collection of return loss ratios as a signature for the TV channel to which the TVR is currently tuned;
6) transmitting channel change command from said infrared transmitter in said external remote control to cause said TVR to change to a new channel;
7) repeating steps 4 and 5 for the new channel;
8) repeating steps 6 and 7 until a signature has been learned for every TV channel.
-
-
22. A setup process for learning the return loss ratio signature of each TV channel comprising steps for:
-
1) transmitting a channel change command to a TVR using a remote control of said TVR so as to tune said TVR to a selected TV channel;
2) periodically or occasionally monitoring leakage from a local oscillator in a tuner of said TVR to determine the frequency at which said local oscillator is oscillating;
3) determining if the current frequency at which said local oscillator is oscillating has changed since the last time the frequency of said local oscillator was counted;
4) if the frequency of said local oscillator has not changed since the last time it was checked, return to step 2, but if the frequency of said local oscillator has changed since the last time it was checked, using the frequency of said local oscillator to determine the channel to which said TVR is tuned and then learn the return loss ratio signature of said TV channel to which said TVR is tuned and store said signature in memory;
5) determine if there is a match between the signature stored in step 4 and signatures previously stored;
6) if step 5 determines there is a match, generating and sending the appropriate commands to control a set top decoder to tune to a downstream channel carrying the TV channel determined in step 5 and recover the data thereof and convert said data to a television signal and modulate an RF carrier having the frequency of the TV channel determined in step 5 with said television signal, 7) determining if all signatures for all channels have been learned, and, if so, thereafter using said signatures in conjuction with return loss ratio measurements on a plurality of probe signals to determine the channel to which a TVR is tuned at any particular time, but if not all signatures have been learned, returning to step 2;
8) if step 5 determines that the signature learned in step 4 does not match any signature previously learned, labelling the signature data gathered in step 4 as the signature for the channel determined in step 4, and then returning to step 2.
-
Specification