Digital demodulator with a low sampling frequency

1. A method for demodulating a signal modulated at least in amplitude, comprising:

performing an analog-to-digital conversion of an input signal by applying a sampling frequency equal to three times the frequency of the modulation carrier; and

extracting amplitude information A from the following relation:

A

=

k

⁢

∑

i

=

1

3

⁢

⁢

e

i

2

;

 where e i designates the value of a digitized sample of rank i among three successive samples provided by said converter, and where k designates a constant; and

wherein the input signal is modulated in phase and in amplitude, phase information φ being extracted from a current sample by applying the following relation:

φ=Arc cos( e i /A ).