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NVP6124

Data sheet

02.11.2015 (REV 0.2)

35/125

4-CH AHD2.0 RX and 9-CH Audio Codec

4. Coaxial Protocol

NVP6124 includes Coaxial Protocol generator that sends control signal from a controller to a pan

and tilt, receiver driver, or camera and lens on the video signal. NVP6124 supports Protocol for

CVBS/COMET(PELCO) & AHD(A-CP). It depends on Coaxial Cable impedance characteristic. This

document presents the concept of Coaxial Protocol. Coaxitron is Pelco’s name for a method of

sending control signaling from a controller to a pan and tilt, receiver driver, or camera and lens on

the video signal (Known

as “Up The Coax” or “UTC”)

4.1. PELCO PROTOCOL

There are two types of Coaxitron command structures. One type, Standard Coaxitron,. is a series

of 15 pulses, or data bits, that are sent within video line 18 of a video field. The other type, Extended

Coaxitron, is a series of 32 pulses, where 16 pulses are sent in line 18 and 16 pulses in line 19 of a

video field. Refer to Figure 4.1. No pulses are sent when the system is in an idle state

Figure 4.1. Coaxitron Active line

Coaxitron is a pulse width modulated (PWM) That is inserted into video vertical blanking interval.

2us pulse represents a one(1) and a 1us pulse represents a zero(0). There is a start bit (always high

level), a data bit (low or high level) and a stop bit (always low level).

Refer to Figure 4.2. and Figure 4.3.

1us

3us

Start

Data

Stop

Figure 4.2. Description of One Coaxitron Bit

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