Line frequency noise

Thread Starter

somaye2022

Joined Mar 23, 2022
99
Hi every one,
I have a problem with the so-called LineNoise.
This is a change of the offset in the image which changes very slowly.
Therefore it looks in the image of linear image sensor G14714-1024DK as if the offset changes a little bit from line to line -> "LineNoise". The Image Sensor need 2.5 V for INP and VINP pins and 2.6 V for PDN pin and maxium 20mA current!
As cause for this fluctuations at the reference voltage inputs of the sensor were found(uploaded).
These are amplified with the adjusted gain and are then superimposed in the image.

How would be possible that I eliminate this noise?
P.S: please let me know, if I should explain more.


Im looking forward to hear from you,
Thank you with best regards
 

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ronsimpson

Joined Oct 7, 2019
2,167
There are many places for noise to get in.
Is your lighting source noise free? Some types of lights have power line noise. 50/60hz power line can cause the light to have 100/120hz noise.
The ADC and its reference might have noise.
The cables might pick up noise.
The power supply(s) you are using could have noise.
Is the noise random or related to 2x the power line frequency?
 

KeithWalker

Joined Jul 10, 2017
2,406
The "line noise" could be from power supply ground currents, electro-magnetically induced in the wiring or from ambient lighting.
What is the source of ambient lighting and Is the noise present when the image sensor is dark?
What are you using to power the sensor and circuitry? Are there any long wires or cables in the installation?
Are the different parts of the circuitry each connected back independently to the supply common in a star arrangement? That will minimize interference caused by ground loops
 

Thread Starter

somaye2022

Joined Mar 23, 2022
99
There are many places for noise to get in.
Is your lighting source noise free? Some types of lights have power line noise. 50/60hz power line can cause the light to have 100/120hz noise.
The ADC and its reference might have noise.
The cables might pick up noise.
The power supply(s) you are using could have noise.
Is the noise random or related to 2x the power line frequency?
Thank you for your reply,

here is a short conclution of the test result until now!
- The measurement of the digital signals shows no abnormality. The signals from the sensor to the ADC are also relatively strongly disturbed!
- The line noise seems to be a pure offset problem, the amplitude is similar in the dark and in the light.
- The noise amplitude is approximately proportional to the gain set in the sensor.
So the disturbance arises before the sensor gain!
This could indicate an unstable supply voltage.
see. This speaks for disturbance already from the sensor itself!

best regards
 

Thread Starter

somaye2022

Joined Mar 23, 2022
99
The "line noise" could be from power supply ground currents, electro-magnetically induced in the wiring or from ambient lighting.
What is the source of ambient lighting and Is the noise present when the image sensor is dark?
What are you using to power the sensor and circuitry? Are there any long wires or cables in the installation?
Are the different parts of the circuitry each connected back independently to the supply common in a star arrangement? That will minimize interference caused by ground loops
Thank you for your reply, there isn't any long wire. No, the noise is not present when the image dark is. here is a short conclusion of the test result until now!
- The measurement of the digital signals shows no abnormality. The signals from the sensor to the ADC are also relatively strongly disturbed!
- The line noise seems to be a pure offset problem, the amplitude is similar in the dark and in the light.
- The noise amplitude is approximately proportional to the gain set in the sensor.
So the disturbance arises before the sensor gain!
This could indicate an unstable supply voltage.
see this speaks for disturbance already from the sensor itself!

with best regards
 
Last edited:
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