Null symbol position detecting method, null symbol position detecting apparatus, and receiver

摘要

Null symbol position detecting method of the present invention, the apparatus and the receiver can quickly and accurately detecting a null symbol from a broadcast signal, including, in the null symbol received any broadcast signal environment. DAB signal is received and tuned and demodulated I / Q-. I and Q signals obtained by the I / Q demodulator is delayed by one effective symbol by the I and Q components, each delay circuit is a delay signal Id and a delay signal Qd respectively. The correlation value between the delay signals Id and Qd and non-delayed signals I and Q are obtained. Peak of the correlation value is determined by a peak decision circuit. Level pattern of the peak is detected by a level pattern decision circuit. If the low-level peak is found, the time interval decision circuit the position of calculating the length of null symbol period by determining whether or not equal to the length of the length of the null symbol included in the received and tuned DAB signal, the null symbol The detected.