An embodiment of an apparatus for channel assessment is provided, comprising a radio frequency (RF) unit, a baseband unit and a microprocessor control unit (MCU). The baseband unit coupling to the RF unit directs the RF unit to selectively hop into one of a plurality of available channels in a frequency band using a pseudorandom sequence to receive a plurality of packets via the hopped channel. The MCU coupling to the baseband unit accumulates a measure for the hopped channel according to reception results of the packets and marks the hopped channel as a bad channel when the accumulated measure exceeds a predetermined threshold. The measure represents the inaccuracy extent during packet reception via the hopped channel.