# US 2019/0170846 A1 · Tracking receiver with integrated phase calibration and method

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- Number: US 2019/0170846 A1
- Document ID: US20190170846A1
- Status: Published application
- Kind: A1
- Application number: 16/209,737
- Filed: 2018-12-04
- Published: 2019-06-06
- Earliest claimed: 2017-12-04
- Assignees: ViaSat, Inc.
- Applicants: Viasat, Inc.
- Inventors: CHRISTOPHER A. ROSE; BRIAN D. CHANDLER; DAVID E. SINYARD; CHARLES M. LUKE
- Web page: https://patentgrep.com/patent/US20190170846A1

## CPC

- G01S 3/023: {Monitoring or calibrating}
- G01S 3/48: the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A system and method of the disclosure relates to satellite tracking. The system may comprise a tracking receiver that includes a first analog-to-digital (A/D) converter coupled between a sum input and a digital signal processor (DSP), a second A/D converter coupled between a difference input and the DSP, and a calibration output coupled to the sum input and coupled to the difference input. The first A/D converter may convert an signal received at the sum input into a sum digital signal, and provide the sum digital signal to the DSP. The second A/D converter may convert an signal received at the difference input into a difference digital signal, and provide the difference digital signal to the DSP. The tracking receiver may generate an calibration signal and provide the calibration signal through the calibration output.

## Claims

### Claim 1

A system for tracking a satellite, comprising:
a tracking receiver, including:
a sum input;
a difference input;
a digital signal processor (DSP);
a first analog-to-digital (A/D) converter coupled between the sum input and the DSP, wherein the first A/D converter is configured to convert a signal received at the sum input into a sum digital signal, and to provide the sum digital signal to the DSP;
a second A/D converter coupled between the difference input and the DSP, wherein the second A/D converter is configured to convert a signal received at the difference input into a difference digital signal, and to provide the difference digital signal to the DSP; and
a calibration output coupled to the sum input and coupled to the difference input; wherein the tracking receiver is configured to generate a calibration signal and provide the calibration signal through the calibration output.

### Claim 2 (depends on 1)

The system of claim 1, wherein the DSP is configured to:
generate a phase correction value based on the sum digital signal and the difference digital signal resulting from the calibration signal coupled to the sum input and coupled to the difference input; and
store the phase correction value.

### Claim 3 (depends on 2)

The system of claim 2, wherein the phase correction value corresponds to a phase difference between the sum digital signal and the difference digital signal.

### Claim 4 (depends on 1)

The system of claim 1, further comprising:
a first calibration signal insertion component coupled between the calibration output and the sum input, and defining a first signal path between the first calibration signal insertion component and the sum input; and
a second calibration signal insertion component coupled between the calibration output and the difference input, and defining a second signal path between the second calibration signal insertion component and the sum input.

### Claim 5 (depends on 4)

The system of claim 4, wherein the first signal path and the second signal path have different phase shifts.

### Claim 6 (depends on 4)

The system of claim 4, wherein the DSP is configured to generate a phase correction value based on a phase difference between the first signal path and the second signal path.

### Claim 7 (depends on 4)

The system of claim 4, wherein:
the first calibration signal insertion component comprises a first coupler having a first antenna signal input, a first calibration signal input, and a first coupled signal output, wherein the first calibration signal input is coupled to the calibration output, and the first coupled signal output is coupled to the sum input; and
the second calibration signal insertion component comprises a second coupler having a second antenna signal input, a second calibration signal input, and a second coupled signal output, wherein the second calibration signal input is coupled to the calibration output, and the second coupled signal output is coupled to the difference input.

### Claim 8 (depends on 4)

The system of claim 4, further comprising:
a first amplifier along the first signal path; and
a second amplifier along the second signal path.

### Claim 9 (depends on 4)

The system of claim 4, further comprising:
a first mixer along the first signal path; and
a second mixer along the second signal path.

### Claim 10 (depends on 7)

The system of claim 7, further comprising:
a data antenna coupled to the first antenna signal input and configured to generate a sum signal; and
an offset antenna coupled to the second antenna signal input and configured to generate a difference signal.

### Claim 11 (depends on 4)

The system of claim 4, wherein:
the first calibration signal insertion component comprises a first switch having a first antenna signal input, a first calibration signal input, and a first switched signal output, wherein the first calibration signal input is coupled to the calibration output, and the first switched signal output is coupled to the sum input; and
the second calibration signal insertion component comprises a second switch having a second antenna signal input, a second calibration signal input, and a second switched signal output, wherein the second calibration signal input is coupled to the calibration output, and the second switched signal output is coupled to the difference input.

### Claim 12 (depends on 1)

The system of claim 1, further comprising:
an antenna assembly configured to generate an antenna sum signal at a sum output, and an antenna difference signal at a difference output, wherein the sum output is coupled to the sum input, and the difference output is coupled to the difference input.

### Claim 13 (depends on 12)

The system of claim 12, wherein the antenna assembly includes a TE21 coupler having the sum output and the difference output.

### Claim 14 (depends on 12)

The system of claim 12, wherein:
the DSP is configured to generate a tracking signal for moving the antenna assembly and to store a phase correction value generated using the calibration signal; and
the tracking signal is generated based on the phase correction value, and a source signal received from a target satellite using the antenna assembly to generate the antenna sum signal and to generate the antenna difference signal.

### Claim 15 (depends on 14)

The system of claim 14, wherein the tracking receiver is attached to the antenna assembly such that the tracking receiver moves with the antenna assembly.

### Claim 16 (depends on 12)

The system of claim 12, wherein:
the antenna assembly has a feed assembly and a reflector; and
the tracking receiver is housed within a can of the feed assembly.

### Claim 17 (depends on 12)

The system of claim 12, wherein the DSP is further configured to store a phase correction value associated with a phase difference between a first signal path through the antenna assembly to the sum output and a second signal path through the antenna assembly to the difference output.

### Claim 18

A method, comprising:
receiving, at a sum input of a tracking receiver, a first calibration signal from an calibration output of the tracking receiver;
receiving, at a difference input of the tracking receiver, a second calibration signal from the calibration output;
converting the first calibration signal into a sum digital signal;
converting the second calibration signal into a difference digital signal; and
generating a phase correction value based on the sum digital signal and the difference digital signal.

### Claim 19 (depends on 18)

The method of claim 18, wherein the phase correction value corresponds to a phase difference between the sum digital signal and the difference digital signal.

### Claim 20 (depends on 18)

The method of claim 18, wherein:
the sum input is coupled to a sum output of an antenna assembly; and
the difference input is coupled to a difference output of the antenna assembly.

### Claim 21 (depends on 20)

The method of claim 20, wherein the antenna assembly comprises:
a data antenna that generates a sum signal at the sum output; and
an offset antenna that generates a difference signal at the difference output.

### Claim 22 (depends on 20)

The method of claim 20, wherein the antenna assembly comprises:
a TE21 coupler that generates a sum signal at the sum output and a difference signal at the difference output.

### Claim 22 (depends on 18)

The method of claim 18, further comprising:
generating a tracking signal based on the phase correction value, and a source signal received from a target satellite using an antenna assembly to generate an antenna sum signal and an antenna difference signal.

### Claim 23 (depends on 22)

The method of claim 22, wherein the tracking receiver is attached to the antenna assembly such that the tracking receiver moves with the antenna assembly in response to the tracking signal.

### Claim 24 (depends on 23)

The method of claim 23, wherein:
the antenna assembly has a feed assembly and a reflector; and
the tracking receiver is housed within a can of the feed assembly.

### Claim 25 (depends on 18)

The method of claim 18, wherein:
a first calibration signal insertion component couples the first calibration signal between the calibration output and the sum input, and defines a first signal path between the first calibration signal insertion component and the sum input; and
a second calibration signal insertion component couples the second calibration signal between the calibration output and the difference input, and defining a second signal path between the second calibration signal insertion component and the sum input.

### Claim 26 (depends on 25)

The method of claim 25, wherein the phase correction value is based on a phase difference between the first signal path and the second path.

### Claim 27 (depends on 25)

The method of claim 25, wherein:
the first calibration signal insertion component comprises a first coupler; and
the second calibration signal insertion component comprises a second coupler.

### Claim 28 (depends on 25)

The method of claim 25, wherein:
the first calibration signal insertion component comprises a first switch; and
the second calibration signal insertion component comprises a second switch.