Strange values at recording.
Posted: Tue Jun 23, 2015 9:04 am
Hi everyone
thank you in advance for your replies. I created a program to record data from the amplifier but there are some values that intrigues me.
Just to clarify, I record 16 channels downsampled to 1024 and each value is divided by 8192 to transform to uV.
This was done following the webpage were they state:
"The receiver converts every 24-bit word from the AD-box into a 32-bit Signed Integer, by adding an extra zero Least Significant Byte to the ADC data. The 24-bit ADC output has an LSB value of 1/32th uV. The 32-bit Integer received for the USB interface has an LSB value of 1/32*1/256 = 1/8192th uV"
Once I start to record I receive in every channel 256 for several seconds (between 5 and 10). That is my first question. Why? Also I didn't found any information regarding that.
After that every channel start to record correctly, but there is a huge offset in every electrode. I attach a picture so you can see it. Basically each electrode has an offset between -1000 and 1000 uV and each of them is different. Why is that? I am recording incorrectly the data?
Thank you,
Jacobo
thank you in advance for your replies. I created a program to record data from the amplifier but there are some values that intrigues me.
Just to clarify, I record 16 channels downsampled to 1024 and each value is divided by 8192 to transform to uV.
This was done following the webpage were they state:
"The receiver converts every 24-bit word from the AD-box into a 32-bit Signed Integer, by adding an extra zero Least Significant Byte to the ADC data. The 24-bit ADC output has an LSB value of 1/32th uV. The 32-bit Integer received for the USB interface has an LSB value of 1/32*1/256 = 1/8192th uV"
Once I start to record I receive in every channel 256 for several seconds (between 5 and 10). That is my first question. Why? Also I didn't found any information regarding that.
After that every channel start to record correctly, but there is a huge offset in every electrode. I attach a picture so you can see it. Basically each electrode has an offset between -1000 and 1000 uV and each of them is different. Why is that? I am recording incorrectly the data?
Thank you,
Jacobo