Method and apparatus to initiate communications between an unknown node and an existing secure network

A method to establish communications between a first node and a second node, comprising:

• receiving at a second node a waveform comprising a preamble portion and a payload portion, the preamble portion comprising a data sequence known to the second node being transmitted with a carrier frequency that varies across a range of carrier frequencies that is bounded by Doppler uncertainty threshold;
• relating a value of the data sequence which was detected at the reception at an acquisition frequency that lies within the range of carrier frequencies;
• correlating a value of the data sequence which was detected at the reception instant at least with a carrier frequency for the payload portion;
• and
• tuning a receiver to the related carrier frequency to receive the payload portion.

A transmitter comprising:

• a first switch alternately coupling to a variable frequency generator and a substantially constant frequency generator;
• a second switch alternatively coupled to a first pseudo-random noise (PN) code input and a second pseudo-random noise (PN) code input;
• a controller for operating said first and second switches simultaneously;
• a modulator having an input coupled to an output of each of said first and second switches;
• and
• at least one transmit antenna having an input coupled to an output of the modulator.

A transmitter for sending a discovery burst, comprising:

• means for spreading a data sequence of a burst preamble with a first pseudo-random noise (PN) code, wherein each and every point of the data sequence is indicative of a unique position within the preamble;
• means for applying a variable frequency profile to the burst preamble, the frequency profile bounded by Doppler uncertainty thresholds;
• means for applying a constant frequency to a burst payload that is spread with a second pseudo-random noise (PN) code;
• means for transmitting the burst preamble at the variable frequency and the burst payload at the constant frequency within a single discovery burst.