Quality indicator:

Excellent illumination:

Status & reason:

The signal quality and the accuracy is excellent and not close to any limits.

Action:

No action necessary. See note below

Quality indicator:

Too bright illumination:

Status & reason:

The signal is close to or above the limit of too much light (maximum signal limit).

Action:

Decrease integration time for the next measurement. See note below

Note:

Generally, the higher the received signal, the better and more precise the distance measurement will be. However, it is good practice to

control the integration time such that an amplitude value between 100 ... 200 LSB is achieved. Higher values will only slow down the acqui -

sition rate due to longer integration times, but are not significantly improving signal to noise ratio.

The rules to apply are the same as for the modulated light amplitude.

The quality indicator for the distance noise is the ratio AMR of ambient-light to the modulated light. This value may be calculated and used

additionally to the above amplitude value if the respective application is subject to intense ambient light.

Quality indicator:

Ratio AMR of ambient-light to modulated light

AMR

[dB] = 20⋅log

E

AC

)

e.g.

AMR

[dB] = 20⋅log

16

μ W/cm

2

tance measurement.

Status & reason:

This ratio is one of the influencing factors on the distance noise (refer to Table 2, section Distance noise)

Action:

< 60 dB: excellent

No action necessary.

< 70 dB: sufficient

Is a lower noise level needed, do the next measurement with a longer integration

time or an increased illumination power.

> 70 dB: weak

Do the next measurement with a longer integration time or an increased illumination

power.

There are also validity indicators delivered by the chip after a measurement. These will help to detect saturated pixels as a result of too

much illumination or too long integration time.

Validity indicator:

MIN_VALID_PIX (refer to chapter 3.2.3.Response: Valid & saturated pixels)

Meaning:

The chip internally detects saturation of pixels and internal signal electronics and flags them non-valid. Since there

are four samples for one measurement, a different number of saturated pixels may internally be detected for each of

the samples. However, the chip output number is the valid pixel count from the sample with the least valid pixels.

The subsequent distance calculation routine uses only this subset of valid pixels. Therefore, the higher the

MIN_VALID_PIX value, the higher the accuracy and reliability of the distance data will be.

How to use:

A low MIN_VALID_PIX value most likely indicates a global saturation of the pixel field resulting from a too long inte -

gration time and/or a too bright illumination. Such a state will also display in the amplitude value (see above).

However, there may be situations where the global illumination is appropriate but there are individual pixels driven into

saturation. This can occur if very bright (high-reflecting) areas are within the scene and blind individual pixels(e.g. a

painted machine part with a small, chrome-polished area). In such a situation, the MIN_VALID_PIX count may help to

differentiate if the shot is still containing enough valid pixels for a reliable distance calculation.

What values are acceptable has to be established within the context of the respective application. As a safe value we

recommend to use only measurements with a value of MIN_VALID_PIX>60.

Validity indicator:

MAX_SAT_PIX (refer to chapter 3.2.3.Response: Valid & saturated pixels)

Meaning:

The MAX_SAT_PIX is a complementary value to the above MIN_VALID_PIX value. But it counts only the saturated

pixels (not the subsequent signal electronics). The lower the MAX_SAT_PIX value, the higher the accuracy and relia-

bility of the distance data will be.

How to use:

Like above.

As a safe value we recommend to use only measurements with a value of MIN_SAT_PIX<5.

Remember, the epc600 chip is using a sensor array with 64 pixels and the single distance output is an average of these pixels. The two

parameters above indicate how many of these pixels are actually used for this average calculation. Refer to the epc600 Handbook for

more details on the averaging algorithm.

Table 6 shows a quality decision matrix as a summary of the validity and quality parameters for the distance measurement.

© 2014 ESPROS Photonics Corporation

Characteristics subject to change without notice

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Datasheet epc600 - V1.3

www.espros.ch