# US 10,120,077 B2 · Distance measuring method and distance measuring element

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- Number: US 10,120,077 B2
- Document ID: US10120077B2
- Status: Granted
- Kind: B2
- Application number: 14/406,475
- Filed: 2013-06-24
- Published: 2015-06-11
- Granted: 2018-11-06
- Earliest claimed: 2012-06-27
- Assignees: Leica Geosystems AG
- Applicants: Leica Geosystems AG
- Inventors: Reto Stutz
- Web page: https://patentgrep.com/patent/US10120077B2

## CPC

- G01S 17/88: Lidar systems specially adapted for specific applications
- G01S 7/4861: Circuits for detection, sampling, integration or read-out
- G01S 7/4865: Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487)
- H03M 1/1245: {Details of sampling arrangements or methods}
- 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
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)

## Abstract

The invention relates to a distance measuring method comprising at least the step of emitting at least one measurement signal to a target object, in which at least one start signal is produced, and the measurement signal is back scattered from the target object as a target signal. Said target signal is sampled at a sampling frequency and the relative position of the start signal and the target signal is determined for deriving a distance to the target object from the relative position from the start signal and the target signal. The sampling frequency can be adjusted and is set in accordance with a large distance to the target object.

## Claims

### Claim 1

A distance measuring method, comprising at least:
emitting at least a first measurement signal to a target object, wherein at least one start signal is generated;
receiving the measurement signal backscattered from the target object as a target signal;
sampling the target signal with a sampling frequency and determining a relative position of the at least one start signal and the target signal, wherein the target signal is sampled at sampling points of a sampling pattern defined by the sampling frequency; and
deriving a distance to the target object from the relative position of the start signal and the target signal;
wherein the sampling frequency is adjustable and is set in a manner dependent on a coarse distance to the target object.

### Claim 2 (depends on 1)

The distance measuring method as claimed in claim 1, wherein:
the sampling frequency is set such that a respective position of the at least one start signal and the target signal relative to the sampling pattern is identical, such that the start and target signals are sampled at identical locations of a respective signal profile.

### Claim 3 (depends on 1)

The distance measuring method as claimed in claim 1, wherein the sampling frequency is set in accordance with at least one of the following relationships:
f
=
⌊
N
⌋
·
c
2
⁢
D
⁢
⁢
and
⁢
⁢
f
=
⌈
N
⌉
·
c
2
⁢
D
wherein:
f denotes the sampling frequency to be set for sampling,
c denotes the speed of light,
D denotes the coarse distance,
N denotes a number of sampling intervals between the at least one start signal and the target signal,
└N┘ denotes a rounding-down function, and
└N┘ denotes a rounding-up function for the number of sampling intervals between the start signal and the target signal.

### Claim 4 (depends on 1)

The distance measuring method as claimed in claim 1, wherein a synthetic distance error is determined for the target signal by linear interpolation of the target signal shifted in terms of its position.

### Claim 5 (depends on 1)

The distance measuring method as method as claimed in claim 1, wherein the coarse distance to the target object is ascertained by means of a coarse distance measurement.

### Claim 6 (depends on 5)

The distance measuring method as claimed in claim 5, wherein:
emitting, receiving and sampling are carried out for a-the first and a second measurement signal, wherein a coarse distance is derived from the first measurement signal and the sampling frequency for sampling the second measurement signal is set in a manner dependent on the coarse distance thus determined.

### Claim 7 (depends on 5)

The distance measuring method as claimed in claim 5, wherein:
the coarse distance to the target object is ascertained in a manner dependent on a time of flight by virtue of the backscattered measurement signal being detected if an intensity thereof exceeds a predefined threshold value.

### Claim 8 (depends on 1)

The distance measuring method as claimed in claim 1, wherein:
the sampling frequency is taken from a table in which suitable sampling frequencies are assigned to coarse distances, wherein the assignment of coarse distances to sampling frequencies is effected on the basis of previous distance measuring processes.

### Claim 9 (depends on 1)

The distance measuring method as claimed in claim 1, wherein the sampling frequency is varied until a first derivative at the sampling points of the target signal is maximal.

### Claim 10 (depends on 1)

The distance measuring method as claimed in claim 1, wherein the measurement signal comprises a light signal.

### Claim 11

A distance measuring element comprising at least:
a measurement signal source for emitting at least one measurement signal to a target object, wherein at least one start signal is generated;
a receiver for detecting the measurement signal backscattered from the target object as a target signal;
a sampling circuit for sampling the received target signal for determining the relative position of the start signal and the target signal, wherein the target signal is sampled at sampling points of a sampling pattern defined by a sampling frequency;
a control and evaluation component for deriving a distance to the target object from a relative position of the start signal and the target signal;
wherein the sampling circuit is designed such that the sampling frequency is adjustable and is settable.

### Claim 12 (depends on 11)

The distance measuring element as claimed in claim 11, wherein the sampling circuit has a frequency generator.

### Claim 13 (depends on 11)

The distance measuring element as claimed in claim 11, wherein the sampling circuit comprises a frequency synthesizer.

### Claim 14 (depends on 11)

The distance measuring element as claimed in claim 11, wherein:
a time-of-flight-measuring measurement circuit for coarse distance measurement, which is designed such that the backscattered measurement signal is detected if an intensity thereof exceeds a predefined threshold value.

### Claim 15 (depends on 11)

The distance measuring as claimed in claim 11, wherein:
a storage unit for storing coarse distances for previously known target objects.

### Claim 16 (depends on 11)

The distance measuring element as claimed in claim 11, wherein a coarse distance measurement signal source and a coarse distance receiver are designed and arranged such that they define a second measurement path independent of the measurement signal source and the receiver.

### Claim 17 (depends on 11)

The distance measuring element as claimed in claim 11, wherein the at least one start signal is generated by splitting the measurement signal.

### Claim 18 (depends on 11)

The distance measuring element as claimed in claim 11, wherein the sampling circuit is automatically settable, in a manner dependent on a coarse distance to the target object.

### Claim 19 (depends on 11)

The distance measuring element as claimed in claim 11, wherein the sampling circuit comprises at least one of a direct digital synthesizer, fractional-N synthesizer, and a voltage-controlled and phase-locked-loop-based integer-N synthesizer.

### Claim 20 (depends on 11)

The distance measuring element as claimed in claim 11, wherein the measurement signal comprises a light signal.