Patent ID: 6868130

Claim:
A transmission mode detector for digital receivers to detect a transmission mode of transmission frames, comprising: a RF tuner for receiving a RF signal and generating an IF (Intermediate Frequency) signal; an envelope detector for filtering the IF signal and generating a rough envelope waveform; a slicer for quantizing the rough envelope waveform into a binary signal with high and low potentials; a glitch remover for removing glitches in the binary signal and generating an envelope signal; an A/D (Analogue-to-Digital) converter for sampling and digitizing the IF signal and generating a digital signal; an I/Q (In-phase/Quadrature) De-multiplexer for extracting an in-phase and quadrature signals in OFDM (Orthogonal Frequency Division Multiplex) symbols from the digital signal; and a mode detection unit for detecting the transmission mode according to a time period of the envelope signal and an auto-correlation of the OFDM symbols.