Patent ID: 8275017

Claim:
A method of transmitting frequency-hopping quadrature amplitude modulation data signals, comprising: transmitting in each of the quadrature channels at an initial carrier frequency f 0 a first signal over consecutive time intervals T 0S , T PN1 , T 01 and T PN2 comprising: transmitting during the time interval T 0S only a first pilot tone signal A 0 · Sin ⁡ ( 2 ⁢ π ⁢ ⁢ f S 2 ⁢ t ) , where f S is a symbol clock frequency and A 0 is an amplitude, at a power equal to a total signal power during data transmission; transmitting during the time interval T PN1 a sum of a second pilot tone signal A 1 · Sin ⁡ ( 2 ⁢ π ⁢ ⁢ f S 2 ⁢ t ) , where an amplitude A 1 is between 0.05 A 0 and 0.1 A 0 , and of a first pseudo noise sequence PN1 multiplied by a cosine signal Cos ⁡ ( 2 ⁢ π ⁢ ⁢ f S 2 ⁢ t ) ; transmitting during the time interval T 01 a sum of the second pilot tone signal and of a first symbol data sequence multiplied by the cosine signal; transmitting during the time interval T PN2 , a sum of the second pilot tone signal and of a second pseudo noise sequence PN2 multiplied by the cosine signal; after transmitting the first signal, transmitting in each of the quadrature channels at an second carrier frequency f i a second signal over consecutive time intervals T S , T PN1 , T 1 and T PN2 comprising: transmitting during the time interval T S only the first pilot tone signal at the power equal to the total signal power during data transmission; transmitting during the time interval T PN1 a sum of the second pilot tone signal, and of the first pseudo noise sequence PN1 multiplied by the cosine signal; transmitting during the time interval T 1 a sum of the second pilot tone signal and of a second symbol data sequence multiplied by the cosine signal; and transmitting during the time interval T PN2 , a sum of the second pilot tone signal and of the second pseudo noise sequence PN2 multiplied by the cosine signal; wherein T S is shorter than T 0S and T 1 is longer than T 01 ; and wherein the second carrier frequency f i = f 0 + c i m i · f S 2 , where c i is a positive or negative integer and m i is a positive integer.