Site Contents

• Introduction
• Audio Data Format
• Interface Applications
• Hardware Specifications
• Data Transmission
• Digital-Analog Converter
• Resetting & Auto-Switching
• History & Characteristics
• Data & Cabling Details
• Coding Format
• Conversion Circuits
• Internal Connection
• External Connection
• Optical Output Circuit
• Transmission Line

Sponsors

SPDIF: Resetting & Auto-Switching

SPDIF Signal

Every time a digital signal is present, the entire circuit needs to be fully reset. In computers and CD players this is not a problem if SPDIF signal is always present. The circuit reset may be done in a simple manual way if necessary. However to start audio decoding, the reset must be done after power up.

Resetting

An automatic re-setter is needed for a project for digital cable converters and any sources switching on and off their SPDIF output at the time of changing channels. If manual pressing of reset is to be avoided at every power up of the unit, automatic re-setter is necessary. The timer present in the circuit would reset the converter till presence of signal. However as soon as the SPDIF signal goes or there is some error, resetting would be caused by the timer till presence of digital signal. In absence of digital signal, a small ticking noise may be caused if relays are not there at the output. In situation of channel surfing, the audio may not occasionally initialize if automatic resetting does not happen each time. The audio however starts after a few seconds.

Auto-switching

When SPDIF or similar signals are present, automatic switching of the main output from an analog input to digital can be done by using relays. When used with some digital cable converters, this may be useful for giving digital output during viewing of digital channels. This permits easy internal and external integration to any receiver. This feature may be of benefit to DVD players. When supplied voltage is more than 15v and when for switching 5v relays are used, a heat sink of small size on the regulator should be used. An inverter can be used for buffering channel status bits although there can be countless modifications of the relay circuit to dispense with use of such inverter.