Patent ID: 7555062

Claim:
Method for detecting the amplitude and/or phase position of an at least partly intensity-modulated signal (P E (t)), in a photonic ranging device, comprises the steps: i) Detecting an instant value of the at least partly intensity-modulated signal (P E (t)), ii) Detecting an instant value of a first reference signal (U m (t)), the first reference signal (U m (t)) having a frequency (ω 2 ) which differs from the frequency (ω 1 ) of the intensity modulation, iii) Mixing the detected instant value of the at least partly intensity-modulated signal (P E (t)) with the detected instant value of the first reference signal (U m (t)) to obtain a mixed-signal value (U Δ ), by the steps of: a) Mixing the detected instant value of the at least partly intensity-modulated signal (P E (t)) with the detected instant value of the first reference signal (U m (t)) to obtain at least a first interim value (l a ), b) Mixing the instant value of the at least partly intensity-modulated signal (P E (t)) with the instant value, multiplied by −1, of the first reference signal (U m (t) to obtain at least a second interim value, c) Forming the difference between the first and second interim values to obtain the mixed-signal value (U Δ ), iv) Detecting an instant value of a second reference signal (U l (t)), the second reference signal (U l (t)) having a frequency (Δω) which differs both from the frequency (ω 2 ) of the first reference signal and from the frequency (ω 1 ) of the intensity modulation, v) Detecting an instant value of a third reference signal (U Q (t)), the third reference signal having the same frequency (Δω) as the second reference signal, but being phase-shifted relative to the second reference signal (U l (t)), vi) Mixing the mixed-signal value (U Δ ) with the detected instant value of the second reference signal (U l (t)) to obtain a first measurement signal value, vii) Mixing the mixed-signal value (U Δ ) with the detected instant value of the third reference signal (U Q (t)) to obtain a second measurement signal value, and viii) Calculating the amplitude and/or phase position of the at least partly intensity-modulated signal (P E (t)) from the two measurement signal values.