TokugawaHeavyIndustries
commented
6 months ago Ideal inbound amplitude is around 0.75. Whatever gain setting though, you'll want zero clipping.
The latest version of the capture application has a real-time amplitude measurement and graph - you can use that for a general idea of the inbound amplitude.
A sure-fire way of getting it dialed in is capturing in 16-bit unsigned and opening the resultant capture in Audacity or another audio processing program (like Adobe Audition) and checking the amplitude mean/mode there.
Remember each disc may require different settings for optimal capture, and in general, the amplitude increases as the track gets closer to the center of the disc.
I have recently discovered your fantastic project and decided to have a Duplicator fabricated using the PCB-Way turn-key project. After spending much time reading and learning how to build and flash the firmware I finally got it working. When I set all the dip-switches to ON (1111), ie the lowest gain setting and make a test capture, ld-decode is unable to detect any frames and continually skips until it reaches the end of file. When I set the gain to 8.5 (1000) ie the highest setting, ld-decode works and runs normally, giving me a result I can view in ld-analyse.
There are 13 other gain settings I could choose from, how do I determine the most optimal setting for my laserdisc player?
I understand the reasoning behind making the gain selectable as most laserdisc players are different and vary in their output RF levels. Should I use my multimeter or oscilloscope to measure the voltage or other value to then perform a calculation to choose the gain? I was unable to find any documentation about choosing the gain, other than the table specifying what the values actually are.