We are running into signal-to noise issues and as I started to look into the code (which I only partially understand), I noticed that it is operating at a non 100% or 50% duty cycle. I understand that <100% allows for active DC offset corrections on the photodiodes due to room light, which is good.
I then put the LEDs onto a photodiode and I see that the duty cycle is quite low. I can can see how this may be useful for a true fluorescence decay where one wants to use a time gate to differentiate between the LED light and a delayed fluorescence signal. However, when I tried Turbidity and Absorption modes (using the GUI.exe), the LED operates in the same duty cycle mode. I can see where pulsing an LED allows more light (thermal/current limits), but the LEDs being used (365 and 470 nm) have absolute pulsed/CW ratings of 1000/700 mA with nominal max currents or 500mA. The code shows that the current is already max limited to 338 mA (PCB-LEDn YY.Y XXX.X, XXX.X = maximum LED current. If left not specified will default at 338 mA.\n")
For our purposes, we would be fine/desire with the LED being on for almost 99% (and use 1% for the room light DC correction). Although we are doing fluorescence, between a blank and the combination of excitation and emission filters on the orthogonal detector, we don't need to measure the florescence signal as a decay and can measure it actively while the LED is on.
Can someone advise how to best increase the SNR for our need (increasing duty cycle of the LED ON state for more photons to integrate on the FL detector).
I'm quite fine with a solution using one of the built in CLI commands (I just don't understand it well enough to know the right way to approach this), but can also, with guidance, edit the cn0503.c code and re-compile and flash a new *.hex via DAPLINK.