# US 2014/0369388 A1 · System, method and apparatus for communication that is insensitive to a sampling clock error

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- Number: US 2014/0369388 A1
- Document ID: US20140369388A1
- Status: Published application
- Kind: A1
- Application number: 14/304,905
- Filed: 2014-06-14
- Published: 2014-12-18
- Earliest claimed: 2013-06-14
- Assignees: Lockheed Martin Corporation
- Applicants: Lockheed Martin Corporation
- Inventors: Thomas M. Parks
- Web page: https://patentgrep.com/patent/US20140369388A1

## CPC

- H04B 13/00: Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
- H04B 2001/6912: {using chirp}
- H04B: TRANSMISSION

## Abstract

A system, method and apparatus for digital communication that is insensitive to a sampling clock error. In one embodiment, a digital communication system that is insensitive to a sampling clock error is provided. The digital communication system includes a transmitting communication unit and a receiving communication unit. The transmitting communication unit is configured to generate a digital data communication signal and includes a modulator configured to modulate digital data such that the modulated digital data communication signal is invariant to a stretched frequency scale resulting from a lack of synchronization with a receiving communication unit. The receiving communication unit is configured to receive the digital data communication signal and includes a demodulator configured to demodulate the digital data.

## Claims

### Claim 1

A digital communication system comprising:
a transmitting communication unit configured to transmit digital data, the transmitting communication unit including a modulator configured to modulate the digital data into a modulated digital data communication signal that is invariant to a stretched frequency scale resulting from a lack of synchronization with a receiving communication unit;
a receiving communication unit configured to receive the modulated digital data communication signal, the receiving communication unit including a demodulator configured to demodulate the digital data from the modulated digital data communication signal that is invariant to the stretched frequency scale.

### Claim 2 (depends on 1)

The digital communication system of claim 1, wherein the modulator is configured to modulate the digital data onto a non-linear chirp carrier waveform, and
the demodulator is configured to demodulate the digital data from the non-linear chirp carrier waveform.

### Claim 3 (depends on 2)

The digital communication system of claim 2, wherein the non-linear chirp carrier waveform is a hyperbolic chirp carrier waveform.

### Claim 4 (depends on 3)

The digital communication system of claim 3, wherein the modulator is configured to modulate the digital data onto the hyperbolic chirp carrier waveform using the equations:
f

(
t
)
=
f
0
kt
+
1
,
kt
>
-
1
k
=
f
0
-
f
T
f
T

T
ϕ

(
t
)
=
ϕ
0
+
2

π


f
0

ln

(
kt
+
1
)
k
.

### Claim 5 (depends on 2)

The digital communication system of claim 2, wherein the non-linear chirp carrier waveform is an exponential chirp carrier waveform.

### Claim 6 (depends on 5)

The digital communication system of claim 5, wherein the modulator is configured to modulate the digital data onto the exponential chirp carrier waveform using the equations:
f

(
t
)
=
f
0

k
t
k
=
f
T
f
0
T
ϕ

(
t
)
=
ϕ
0
+
2

π


f
0

(
k
t
-
1
)
ln


k
.

### Claim 7

A method for digital communication, the method comprising:
obtaining digital data for transmission;
modulating the digital data into a modulated digital data communication signal that is invariant to a stretched frequency scale resulting from a lack of synchronization with a receiving communication unit; and
a transmitting communication unit transmitting the modulated digital data communication signal.

### Claim 8 (depends on 7)

The method of claim 7, wherein modulating the digital data into the modulated digital data communication signal includes modulating the digital data onto a non-linear chirp carrier waveform.

### Claim 9 (depends on 7)

The method of claim 7, further comprising:
a receiving communication unit receiving the modulated digital data communication signal; and
demodulating the digital data from the modulated digital data communication signal.

### Claim 10 (depends on 9)

The method of claim 9, wherein demodulating the digital data from the modulated digital data communication signal includes demodulating the digital data from a non-linear chirp carrier waveform.

### Claim 11 (depends on 8)

The method of claim 8, wherein the non-linear chirp carrier waveform is a hyperbolic chirp carrier waveform.

### Claim 12 (depends on 11)

The method of claim 11, wherein modulating the digital data onto the hyperbolic chirp carrier waveform includes modulating the digital data using the equations:
f

(
t
)
=
f
0
kt
+
1
,
kt
>
-
1
k
=
f
0
-
f
T
f
T

T
ϕ

(
t
)
=
ϕ
0
+
2

π


f
0

ln

(
kt
+
1
)
k
.

### Claim 13 (depends on 8)

The method of claim 8, wherein the non-linear chirp carrier waveform is an exponential chirp carrier waveform.

### Claim 14 (depends on 13)

The method of claim 13, wherein modulating the digital data onto the exponential chirp carrier waveform includes modulating the digital data using the equations:
f

(
t
)
=
f
0

k
t
k
=
f
T
f
0
T
ϕ

(
t
)
=
ϕ
0
+
2

π


f
0

(
k
t
-
1
)
ln


k
.

### Claim 15

A transmitting unit for a digital communication system, the transmitting unit including:
an interface configured to obtain digital data for transmission;
a modulator connected to the interface, the modulator configured to modulate the digital data into a modulated digital data communication signal that is invariant to a stretched frequency scale resulting from a lack of synchronization with a receiving communication unit;
an antenna connected to the modulator, the antenna configured to transmit the digital data communication signal.

### Claim 16 (depends on 15)

The transmitting unit of claim 15, wherein the modulator is configured to modulate the digital data onto a non-linear chirp carrier waveform.

### Claim 17 (depends on 16)

The transmitting unit of claim 16, wherein the non-linear chirp carrier waveform is a hyperbolic chirp carrier waveform.

### Claim 18 (depends on 17)

The transmitting unit of claim 17, wherein the modulator is configured to modulate the digital data onto the hyperbolic chirp carrier waveform using the equations:
f

(
t
)
=
f
0
kt
+
1
,
kt
>
-
1
k
=
f
0
-
f
T
f
T

T
ϕ

(
t
)
=
ϕ
0
+
2

π


f
0

ln

(
kt
+
1
)
k
.

### Claim 19 (depends on 16)

The transmitting unit of claim 16, wherein the non-linear chirp carrier waveform is an exponential chirp carrier waveform.

### Claim 20 (depends on 19)

The transmitting unit of claim 19, wherein the modulator is configured to modulate the digital data onto the exponential chirp carrier waveform using the equations:
f

(
t
)
=
f
0

k
t
k
=
f
T
f
0
T
ϕ

(
t
)
=
ϕ
0
+
2

π


f
0

(
k
t
-
1
)
ln


k
.