Patent ID: 11933919
Assignee: MIXED-SIGNAL DEVICES INC.
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G  H

Claim 7:
8. The direct frequency synthesizer of claim 6, wherein a frequency hopping signal is expressed by the following equation:

x(t)=sin(2πf(t)t+θ0)

f(t)=frand(n),tn-1≤t<tn,n∈[1, . . . ,N]

wherein:
f1, . . . , fN: list of frequencies used in a frequency hopping system
t1, . . . , tN: frequency hopping time
rand(n): random frequency mapping in the frequency hopping system
θ0: initial phase of a sine wave
wherein:
the frequency hopping signal is synthesized digitally and digital codeword xn is converted to the analog signal through the high speed digital to analog converter (HS DAC);
wherein:
the relationship between x(t) and xn is given by the following equation:

xn=x(t=nTs)=sin(2πf(t)nTs+θ0)=sin(2πfc(t)n+θ0)

fc(t)=frand(n)Ts,tn-1≤t<tn,n∈[1, . . . ,N]

wherein:
Ts: sample period of a HS DAC clock
wherein, if a sample clock is non-stationary, the digital codeword xn is adjusted so an output frequency stays at a desired frequency by the following equation:

xn′=x(t=nTs′)=sin(2πf(t)nTs′+θ0)=sin(2π(fc(t)+Δfc(t))n+θ0)

wherein:
Ts: non-stationary sample period of the HS DAC clock (Ts′=Ts+ΔTs)
Δfc(t): frequency control word error (Δfc(t)=fc(t)*ΔTs/Ts).