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Technology
WiDIF-HP Technology
A new high-profile format for the digital audio interface on UHF – WiDIF-HP -- has been developed for the DWX series.
This section provides further details on WiDIF-HP technology.
A digital audio wireless transmission system handles audio after the analog signal has been converted into digital form by an A/D
converter.
In conventional analog wireless systems, the compander providing compression and expansion is a key component for enabling wide
dynamic range. The compander system uses complex analog circuitry for maintaining sound quality and response characteristics.
However, this analog system requires advanced techniques to keep performance levels constant, because analog circuits are subject
to the performance instability and adjustment tolerances of parts.
By contrast, the digital audio wireless transmission system is free from such instabilities as it does not require a compander system. In
short, digital audio wireless transmission is an optimum system to transmit high-quality audio signals without deterioration.
WiDIF-HP Technology Outline
Transmitter
Microphone
24 bit
Mixer
Amp.
A/D
CODEC
Channel
Coder
Digital
Modulator
Full digital processing
Digital modulation
RF Block
48 kHz
Upon receiving the modulated carrier wave from the transmitter, the receiver reproduces the digital audio signal and outputs it as either
an analog or digital signal to audio equipment such as an audio mixer or a power amplifier. This section describes the processes that
occur within the receiver.
In the RF block, the received signal is digitized by the A/D converter. Similar to the transmitter, three main processes are then performed
in the signal processing block: digital demodulation, channel decoding, and codec processing.
After receiving the signal from the RF block, the digital demodulator reproduces the digital stream that was channel coded at the
transmitter. Then the channel decoder performs synchronization, decryption, error processing, and audio data extraction. The codec
expands the signal that was data reduced to a low bit rate in the transmitter and reconstitutes the digital audio signal. The reconstituted
digital audio signal is routed through the D/A converter and amplifier to be output as an analog audio signal or as a digital signal
corresponding to standard audio interface specifications such as AES/EBU.
Receiver
24 bit
Mixer
Camcorder
Amp.
D/A
Channel
Decoder
AES/EBU
Full digital processing
RF Block
48 kHz
Digital
Demodulator
CODEC
The transmitter in the digital audio wireless transmission system digitizes analog audio signal inputs from microphones and mixers and
then wirelessly transmits them as a digital signal. This section describes the processes that occur within the transmitter.
An analog audio signal is first amplified in the amplifier and digitized in the A/D converter. The codec then applies data reduction
techniques to the digital signal from the A/D converter and transcodes it into a digital bit stream with a lower bit rate. In the channel
coding section, sync data and error processing data required for wireless transmission are added to the audio data, and the resulting
data are encrypted. The digital modulator generates the π/4 QPSK modulation signal used to transmit the channel coded digital stream
over the digital wireless link. The modulated signal is supplied to the RF block which amplifies the modulated carrier to the power level
required for transmission.
Technology