old school tvl is pretty much irrelevant. tvl is the measurement of the centre 2/3 of a tube from a tube camera.
last tech was D1 which was 704x576 pixels, approx 480 tvl
then was 960h, ie 960x576, still at best 500 tvl
but new stuff is megapixel, how that converts to a tech reading from the 50's i dont get
2mp is 1920x1080 which has obvious benefits