Dear all expert

Please help me, urgent. i'm cctv system installer from malaysia. i used video over cat5e in one of my project, total got 11 cameras but almost every camera won't display properly in my PC-based DVR system. but it can display quite ok when directly plug-in to TV. The cat5e cable length is around 150m (cat5e cable resistance is 10ohm/100m). RG59 Cables length from cameras to Active Type Video Transmitters (Model : TTA-111VT) are from 10m to 250m. i use pasive type video receiver located beside DVR and use short distance (1m) RG59 cable to connect from video receiver to DVR. i notice that the longer the cable distance from camera to video transmitter the image become more terrible. I tried to adjust the transmitter's Level (L/M/H) also didn't solve the problem. when switch to L, the image become B/W, when switch to M or H, some of them got color partially and the image were rolling, there was a black bar at bottom of image, and even the image was hanging there for a few second. i really don't know what is going wrong, if anyone experienced or know how to solve my problem please help me. my email is angkimhua@hotmail.com. i would appreciate for your kindly to share your valuable knowledge.

Best Regards,

Ang Kim Hua

angkimhua@hotmail.com

Hi there,

This sounds like you are getting video loss due to the distances that you are running the cables. First thing to check is to see what video levels your are getting, test the signal with oscilloscope, paying attention to the sharpness of the video in the 1v Peak to Peak scale. Also make sure that the croma burst is within the correct range and looks sharp. This should confirm if its signal problems.

My other concern is that you state that you are running Cat5e for Approx 150 metres and then a coax for another 250 metres. The problem being that running coax 250 metres by itself can cause signal level problems depending on the enviroment and quailty of the coax (again another job for the oscilloscope). The problem that i have faced with the Cat5e converters is that the system can blead out colour aswell as being prone to external interfearance (ground loops, mains hum etc) especially when being connected to a system that will compress the video signal (DVR's, Transmitters etc) so it might be advisable to try an active trasmitter on one camera to see if that boosts the signal and helps with this problem.

Hope that this helps

AT1

Edited March 4, 200818 yr by AdproTech1

cam you use both active and passive baluns on the same cable?

I always thought you had to use 'active' receivers with 'active' transmitters.

Short distance = Passive transmitter + Passive receiver

Medium distance = Passive transmitter + Active receiver

Long distance = Acitve transmitter + Active receiver

we have found that using cheaper/budget baluns does not work any where near as well as using NITEK or NVT...

check your distances are well within the colour tollerances specifeid for the products, keep coax as short as possible and make sure that any ducts are dry as cables through water will be affected (Capacitance)

hope this helps

Are there issues with 'up the coax' telemetry with 'active' transmitters and recievers? Or have I been mis-informed?

Are there issues with 'up the coax' telemetry with 'active' transmitters and recievers? Or have I been mis-informed?

yes it would be good practice to strip out the telemetry/data onto a seperate pair

Dear All Experts

Very thank you for yours advises. Finally i've found whats going wrong and also found the solutions for it.

my problem definately is signal loss causes by cables too long. I didn't change the cable and also didn't use any signal booster. I only change the PC-based video capture card which its signal acception range can be adjusted. And finally it work.

Thank you very much.

:)