Noise generator
View Patent ↗A noise generator for generating band-limited noise from a plurality of sinusoidal signals at the same level and equidistant frequency position in the noise spectrum is provided. A noise signal has a low crest factor and for this purpose the phase position of each individual sinusoidal signal is determined.
1. A noise generator for generating a band-limited noise:
a memory to store respective digital samples of an in-phase (I) signal component and a quadrature (Q) signal component of a noise signal;
respective digital-to-analog converters coupled to the memory to supply respective digital signals respectively corresponding to the in-phase (I) signal component and the quadrature (Q) signal component of the noise signal; and
a vector modulator responsive to a carrier frequency to modulate in a baseband the respective digital signals respectively corresponding to the in-phase (I) signal component and the quadrature (Q) signal component of the noise signal, wherein the vector modulator generates a plurality of sinusoidal signals at a same level and equidistant frequency position in a noise spectrum,
wherein the vector modulator is configured to determine a phase position for each individual sinusoidal signal of the plurality of sinusoidal signals according to
φ
k
=
2
π
T
START
k
+
π
k
2
(
T
STOP
-
T
START
)
N
+
C
π
(
k
-
N
/
2
)
4
(
N
/
(
T
STOP
-
T
START
)
)
2
wherein
k represents the individual sinusoidal signal,
N represents the plurality of sinusoidal signals,
T STOP represents any desired value between 0 and 1,
T START represents any desired value between 0 and 1, and wherein T STOP >T START , and
C represents any desired positive value.
2. The noise generator as claimed in claim 1 , wherein the carrier frequency is phase modulated.
3. The noise generator as claimed in claim 1 , wherein a noise spectrum with gaps is generated by summing individual noise signals, each individual noise signal occupying separate time domains of a signal period.
4. The noise generator as claimed in claim 2 , wherein a noise spectrum with gaps is generated by summing individual noise signals, each individual noise signal occupying separate time domains of a signal period.
5. The noise generator as claimed in claim 3 , wherein the envelope of the noise signal has a constant level and the lengths of the separate time domains are determined in accordance with the outputs of the individual noise bands.
6. The noise generator as claimed in claim 4 , wherein the envelope of the noise signal has a constant level and the lengths of the separate time domains are determined in accordance with the outputs of the individual noise bands.
7. The noise generator as claimed in claim 1 , wherein the edges of the noise spectrum are formed in accordance with a cos 2 -function.
8. The noise generator as claimed in claim 2 , wherein the edges of the noise spectrum are formed in accordance with a cos 2 -function.
9. The noise generator as claimed in claim 3 , wherein the edges of the noise spectrum are formed in accordance with a cos 2 -function.
10. The noise generator as claimed in claim 4 , wherein the edges of the noise spectrum are formed in accordance with a cos 2 -function.