Hi,
i understand your interest on this project, when you connect any device out side the TV, say at the antenna input etc, you can NOT trace the frequency the TV is tuned on.
what you can do is to find a way to detect the local oscilator frequency in the TV set, it will be a very weak signal. if you have a high frequency counter you can wire it from inside to read it.
then you need a data base of TV frequency locally used for the channels of your interest and a micro processor assisted system to compare and log the channel and duration. i think its not a simple task, you need strong knowledge to make a device for that.
i may be able to help little bit by directing you to possible ways, if you explain your requirement more specifically.
best of luck
Razeen
saudi arabia