Ok... I've been trying to read up a little on these FPV cameras and gear in order to consider using them for a security camera that has good low light images without the need for additional IR LED's ... and found some of what I mentioned here already may not apply completely or something like that. Because of the following info, I'm scraping the idea to use one of these cameras for a security camera even though I'm impressed with some of the low light capabilities some of these have. I still want higher actual resolutions as well and these analog FPV cameras don't provide that.
In the USA, we standardize on using NTSC video encoding ( PAL in other areas around the globe ). The resolution and frame rate for NTSC is 720x480 @30fps ...
The TVL's ( TV lines ) is another aspect that describes how many black and white TV lines are in a single frame. For example, a 600TVL camera will have 300 black and 300 white alternating lines of resolution, so a 1200TVL camera will double that. However due to the limitations of the 5.8Ghz video transmissions that doesn't always mean a higher quality video image due to those limitations. Your other equipment, ie the transmitter, receiver and the monitor ( or goggles ) you are using also come into play. In short, a 1200TVL camera will not be twice as sharp as a 600TVL because of the additional limitations.
So don't judge your purchase on that number ( TVL ) base it on the actual image quality you see. In other words, as I suggested before, watch the video reviews and look at what image appears best to you... don't base it on specs alone.