HDMI cable
The data cable used for the HDMI interface is a special STP cable with overall shielding, i.e. S/STP, which has significantly lower attenuation values than known STP and FTP cables. Terminated are HDMI cables with HDMI connectors.
An HDMI cable is a 19- pin cable consisting of four twisted and separately shielded TP wires and five single-core control wires, terminated with HDMI connectors. Transition Minimized Differential Signaling( TMDS) is used for transmission. Of the four twisted-pair wires, three are used for the video and audio data (TMDS 0 to TMDS 2), and the fourth is used for the TMDS clock data.
The Display Data Channel( DDC) is transmitted via another pair of wires and the HPD signal (Hot Plug Detect) and the supply voltage of 5 V via individual wires. In addition to the 19-pin version for single- link connections, there is also the 29-pin HDMI cable for dual-link and the HDMI connector type B, which is not used in consumer electronics, however.
The flexible HDMI cable is optimized for low crosstalk and high attenuation crosstalk ratio( ACR), providing the highest signal integrity of high-speed lines for data and clock signals. Typical attenuation values for a 28 AWG cable at 2 GHz are -4 dB over a 100 m cable length. This is several decibels better than comparable STP cables. It is also backward compatible with the Digital Visual Interface( DVI). A prerequisite for communication between two HDMI components, however, is that both support High-Bandwidth Digital Content Protection( HDCP). Cable lengths of 15 m are specified, and cable diameters range from 6 mm to 10 mm.
With the specification of HDMI 1.3, HDMI cables were divided into two categories: There is category 1, cat 1, for a maximum TMDS clock frequency of 74.25 MHz and category 2, cat 2, with up to 340 MHz clock frequency. In addition, there is another cable specification that is based on the Digital Visual Interface (DVI), this cable specification is called Cable V1.2 and can transmit TMDS clock frequencies of 165 MHz.