Hi, I would discuss with you solutions ro reduce this annoying effect.
Since I put the DVR on the same 12V of cameras (and it should be that, since I'm using a big battery 12V to keep system always on) on some cameras (depending on the leght of cable, model, and maybe some other factors) appear those annoying lines when the HDD records, this is for sure an RF noise, catched by ground loop between DVR negative pole, camera's negative pole and shield of coaxial cables. I think it happens worse, when I use cat5e cabels and baluns, since the signal pair runs in touch with other 3 pairs that I use for 12V, and betwwen baluns there also are difference Dahua's filter better noise then others.
To resuce it I've wrapped some coil on a small thoroid, half for positive pole, half for negative, wth the same direction. Alternatively, to spare some time, I've started the process with 2 segments of enameled wire and covered all thoroid, to get the same result. Two ceramic capacitors of 0,22uF 50V at both sides complete the circuit. I've put it on the DVR power line, both + and - wires.
Effectively I reduced them in this way, but on one system they still present, do you have better solutions? I'm guessing if it can be better to filter the HDD power only, but it this way I'll ruin the DVR power adapter and eventually can be not good for guarantee, but I feel I need to try that.
I suppose it depends on the model of HDD, with some (Seagate VX) it may be stronger, for sure with Hikvision DVR I've never had such problem, so for sure this problem is related only with Dahua XVR, unfortunately.
Thank you for your contribute
Since I put the DVR on the same 12V of cameras (and it should be that, since I'm using a big battery 12V to keep system always on) on some cameras (depending on the leght of cable, model, and maybe some other factors) appear those annoying lines when the HDD records, this is for sure an RF noise, catched by ground loop between DVR negative pole, camera's negative pole and shield of coaxial cables. I think it happens worse, when I use cat5e cabels and baluns, since the signal pair runs in touch with other 3 pairs that I use for 12V, and betwwen baluns there also are difference Dahua's filter better noise then others.
To resuce it I've wrapped some coil on a small thoroid, half for positive pole, half for negative, wth the same direction. Alternatively, to spare some time, I've started the process with 2 segments of enameled wire and covered all thoroid, to get the same result. Two ceramic capacitors of 0,22uF 50V at both sides complete the circuit. I've put it on the DVR power line, both + and - wires.
Effectively I reduced them in this way, but on one system they still present, do you have better solutions? I'm guessing if it can be better to filter the HDD power only, but it this way I'll ruin the DVR power adapter and eventually can be not good for guarantee, but I feel I need to try that.
I suppose it depends on the model of HDD, with some (Seagate VX) it may be stronger, for sure with Hikvision DVR I've never had such problem, so for sure this problem is related only with Dahua XVR, unfortunately.
Thank you for your contribute