What do you mean by single-drive and double-drive of bolt camera?

Single-drive and double-drive in the parameters of the bolt camera refer to the driving mode of the lens aperture. Double-drive refers to video driving and DC driving at the same time, and single-drive can only be video driving or DC driving.

Video Drive (VD for short) means that the camera outputs the video signal level to the inside of the automatic aperture lens, and then the driving circuit inside outputs the control voltage to make the aperture adjustment motor of the lens rotate;

DC Drive (DD, for short) means that the driving circuit of lens diaphragm motor is added in the camera, which can directly output DC control voltage to the diaphragm motor in the lens and make it rotate. This mode is sometimes called Direct Drive. Therefore, the cost of a camera with a DC drive interface is slightly higher (because some circuits are added), but the selected automatic aperture lens is slightly smaller and cheaper because it does not contain a drive circuit inside.

automatic aperture lens interface definition diagram: