Filtering identifier for an OFDM system
View Patent ↗A broadcast TV signal is a DVB-T2 based system. A DVB-T2 transmitter checks OFDM symbols before transmission to determine a level of adjacent channel interference (ACI). If the of level of ACI is too high, i.e., above a threshold value, the OFDM symbols are filtered before transmission. Otherwise, the OFDM symbols are transmitted without filtering. A filtering field is added to an LI pre-signaling table of the broadcast DVB-T2 signal to signal a DVB-T2 receiver when the received OFDM symbols have been filtered.
1. A receiver comprising:
an orthogonal frequency division multiplexed (OFDM) receiver for receiving an OFDM broadcast signal, the received OFDM broadcast signal conveying frames, each frame comprising a preamble portion and a following data portion; wherein at least one preamble portion conveys information to the receiver if a following data portion has, or has not, been filtered prior to transmission; and
a processor, responsive to the information if a following data portion has, or has not, been filtered prior to transmission, for controlling a filter to process the following data portion to compensate for being filtered prior to transmission.
2. The receiver of claim 1 , wherein the OFDM broadcast signal is formatted in accordance with DVB-T2.
3. The receiver of claim 2 , wherein each frame is a T2 frame and the preamble portion is an L1 pre-signaling table.
4. A method for use in a receiver, the method comprising:
receiving an orthogonal frequency division multiplexed (OFDM) broadcast signal, the received OFDM broadcast signal conveying frames, each frame comprising a preamble portion and a following data portion; wherein at least one preamble portion conveys information to the receiver if a following data portion has, or has not, been filtered prior to transmission; and
responsive to the information if a following data portion has, or has not, been filtered prior to transmission, filtering the following data portion to compensate for being filtered prior to transmission.
5. The method of claim 4 , wherein the OFDM broadcast signal is formatted in accordance with DVB-T2.
6. The method of claim 5 , wherein each frame is a T2 frame and the preamble portion is an L1 pre-signaling table.