What does the TVL rating mean for FPV cameras?

Question

I see listings for analog FPV cameras like this one which have ratings in units of TVL. (e.g. 1000 TVL or 1200 TVL) What is TVL?

Answer 1

TVL (TeleVision Lines) is a measurement of the "resolution" of an analog camera. Digital video systems use pixel resolution to specify how many pixels wide and tall the image is (e.g. 1080p = 1920 pixels wide by 1080 pixels tall), but analog video systems don't technically have pixels so there has to be some other way to represent their resolution capabilities.

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The horizontal resolution power of analog video (TVL) measures how many distinct vertical bars can be depicted by the device (either a camera or display screen) across a horizontal length equal to the height of the picture. The example diagram above shows analog video with 6 TVL.

Cameras with higher TVL ratings will be able to capture smaller details than other cameras, although this is also dependent on the capabilities of the other equipment in between the camera and your FPV goggles or screen.

Answer 2

So the question is old but still isn't really answered. Its also useful to anyone who can't get the best possible image from their gear.
A 4:3 sensor (which most are) has say 1200 vertical so it has only three quarters of that in the horizontal. 1200 sounds better but in the world of digital we talk horizontal (ie 1080p...). So from that perspective its putting out 900 lines. If your goggles do 600L then you are likely wasting your money on a higher res camera than 800TVL. However if your goggle do 720L you'd do better with 1000TVL as the goggles tend to spray the screen to fit and you get what looks like blur. Sometimes more is better!