Interference Due To Telemetry !

[BobClarke]

Hi All ,

I have just started woking at another cctv company and while checking the cameras i found that one of them has interference (noise) when i pan/ tilt .

The video out put from the camera go's to a nvt via a short rg59. The nvt is with the camera in the housing !

I am not able to move the nvt, do you think the noise is induced due to being in the camera housing ?

Any advice most welcome.

[djandysp]

Hi All ,

I have just started woking at another cctv company and while checking the cameras i found that one of them has interference (noise) when i pan/ tilt .

The video out put from the camera go's to a nvt via a short rg59. The nvt is with the camera in the housing !

I am not able to move the nvt, do you think the noise is induced due to being in the camera housing ?

Any advice most welcome.

Doubt its the housing mate, possibly a cable running near mains

[SUBS]

Doubt its the housing mate, possibly a cable running near mains

[SUBS]

Hi All ,

I have just started woking at another cctv company and while checking the cameras i found that one of them has interference (noise) when i pan/ tilt .

The video out put from the camera go's to a nvt via a short rg59. The nvt is with the camera in the housing !

I am not able to move the nvt, do you think the noise is induced due to being in the camera housing ?

Any advice most welcome.

What telemetry is it, co-ax or twisted pair, and what kind of P&T head.

reason i ask is that most DC heads use pulsed DC (aka PCM) which could appear as noise or lines. which is one reason why cable from the feedback pots to the reciever should be screened & earthed at one end.

Another thought is that it may be to do with earthing, I had a similar problem with a site that had Conway kit where the mains earth had been lifted to ' cure ' a hum problem. everything worked, but there were digonal stripes when the camera was moving. I'm pretty sure that some NVT baluns / hubs isolate the earth. so there may be a clue there.

if its co ax telemetry, is the termination correct ?

[BobClarke]

What telemetry is it, co-ax or twisted pair, and what kind of P&T head.

reason i ask is that most DC heads use pulsed DC (aka PCM) which could appear as noise or lines. which is one reason why cable from the feedback pots to the reciever should be screened & earthed at one end.

Another thought is that it may be to do with earthing, I had a similar problem with a site that had Conway kit where the mains earth had been lifted to ' cure ' a hum problem. everything worked, but there were digonal stripes when the camera was moving. I'm pretty sure that some NVT baluns / hubs isolate the earth. so there may be a clue there.

if its co ax telemetry, is the termination correct ?

Hi again ,

The p&t is a videmech and the telemetry is RS 244 with UTP.

When it is moved i get broken white diagonal stripes .

[SUBS]

still sounds like an earth problem to me.

is it a fault just appeared, or been there sinci install ?

I'd check the earths, make sure the cameras elecrically isolated from the housing, if its screened utp, try lifting the screen at the housing end.

if your diagonal white lines change, or get closer together when the head speeds up, its definitely coming from the 24v ptz feed. I spose it could be something like a duff de coupling cap in the receiver pcb.