range

n-1

operational

range

n

range

n+1

range

n+2

range

n-2

Distance R

Exposure time (Integration time)

R

0

2

R

0

2

R

0

R

0

R

R

2

T

0

0.5

⋅T

0

0.25

⋅T

0

4

⋅T

0

Figure 15: Example of operating ranges as a function of distance and exposure time

based on doubling the light power to the sensor per range

1.3.3. Ambient-light suppression

light sources e.g. sunlight, daylight, room illumination, etc., from the measuring signal. The user has not to take care of this, it is done by

the chip automatically. To see the capability of this function, refer to Table 3 for example values as a function of the wavelength and com-

pared to sunlight.

Similar to the system's sensitivity of the modulated light, is the ambient-light suppression a function of the integration time. The longer the

integration time, the more the measurement becomes sensitive to the ambient-light.

Notes:

■ The ambient-light suppression of the chip must not be confused with the ambient-light measurement command. It is a fixed built-in func-

tionality, which is removing the DC light component from the AC measurement signal only.

■ A DC or AC photo-signal can be generated by ambient-light (e.g. sunlight) or by cross-talk from the IR-LEDs. If this signal is above the

stated maximum value, then the sensor or the input electronics are saturated. This blocks the detection of the AC modulation signal.

1.3.4. Quality of the measurement result

The epc600 provides information on the quality and the validity of the received optical signal. This reflects the confidence level of the mea -

surement result. The better the received signal, the better and more precise the distance measurement will be.

After each measurement this needs to be calculated from the Q-subsamples QSx delivered by the chip(r efer to chapter 3.2.4. Response:

Q-subsample QSx). This amplitude value is the feedback parameter that is used to set the integration time for the next measure -

ment.

1

4

⋅

4

+

(QS1+QS3)

2

4

Quality indicator:

Weak illumination:

e.g.

50 LSB

Status & reason:

The signal has a reduced accuracy, because it is above, but close to the noise level.

Action:

Increase integration time for the next measurement

Quality indicator:

Sufficient illumination:

e.g.

Status & reason:

The signal quality and the accuracy is sufficient and not close to any limits. Noise level may be increased.

Action:

No action necessary. See note below

© 2014 ESPROS Photonics Corporation

Characteristics subject to change without notice

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Datasheet epc600 - V1.3

www.espros.ch