Detecting preambles of data packets
View Patent ↗Fast detection of a selected portion of a data packet (e.g. the preamble of a Bluetooth data packet) is accomplished by defining a reference signal waveform conforming to an expected waveform representing a signal modulated in accordance with the selected portion of a data packet. A waveform representing a received data signal containing a data packet with the selected portion is derived, and the reference signal waveform is correlated with this derived waveform to produce a correlation result. This correlation result is used to identify the selected portion in the received data signal.
1. A method of detecting a preamble of a data signal formatted to conform to a wireless communications standard, comprising the steps of:
defining a reference cosine signal waveform;
receiving a data signal containing said preamble;
deriving a waveform representing said data signal containing said preamble;
correlating said reference cosine signal waveform with said waveform representing said data signal containing said preamble to produce a correlation result;
identifying said preamble in said data signal in accordance with said correlation result; and
comparing a part of the data signal other than said preamble with a predetermined criterion, and confirming identification of said preamble in accordance with a result of such comparison.
2. The method of claim 1 , wherein said waveform representing said data signal is derived to represent a modulation characteristic of said data signal in accordance with data in said data packet.
3. The method of claim 2 , wherein said data signal is a frequency-shift keyed signal and said waveform representing said data signal is derived to represent frequency deviation of said data signal as a function of time.
4. The method of claim 1 , wherein said wireless communications standard is a Bluetooth wireless communications standard.
5. The method of claim 1 , wherein the part of the data signal other than said preamble comprises a portion of a sync word in the data signal.
6. The method of claim 5 , wherein the part of the data signal other than said preamble comprises six most significant bits of the sync word.
7. An apparatus for detecting a preamble of a data signal formatted to conform to a wireless communications standard, comprising:
a waveform generator for defining a reference cosine signal waveform;
a receiver for receiving a data signal containing said preamble, and for deriving a waveform representing said data signal containing said preamble; and
a correlator for correlating said reference cosine signal waveform with said waveform representing said data signal containing said preamble to produce a correlation result, identifying said preamble in said data signal in accordance with said correlation result, comparing a part of the data signal other than said preamble with a predetermined criterion, and confirming identification of said preamble in accordance with a result of such comparison.