Lost in VIDEO signal
 

Hi ,

We have a CCTV cam (Bosh WZ18) that is 1500 feet from the LCD display.

The cable that was used is a RG59 and having 2 splices (2 junctions).

The video signal is poor , we can see tha image but with lines and
it's noisy.

Is there a way to improve or "rebuild" the signal ?

I tried a VID-AMP SPECO / PROVIDEO VID-AMP 1 IN / 1 OUT VIDEO
AMPLIFIER but did not help.

http://www.surveillance-video.com/vid-amp.html

Lost in VIDEO signal
 

benitos wrote:
Hi ,

We have a CCTV cam (Bosh WZ18) that is 1500 feet from the LCD display.

The cable that was used is a RG59 and having 2 splices (2 junctions).

The video signal is poor , we can see tha image but with lines and
it's noisy.

Is there a way to improve or "rebuild" the signal ?

I tried a VID-AMP SPECO / PROVIDEO VID-AMP 1 IN / 1 OUT VIDEO
AMPLIFIER but did not help.

http://www.surveillance-video.com/vid-amp.html


A few questions to maybe lead you to the problem...
Do you have a good picture when the display is connected close to the
camera? If not, then either the camera or the display is bad. If yes, then
the coax or the splices might be bad. Does the picture degrade when the amp
is connected?
Where do you have the video amp installed? It should be close to the
camera; not the display.
Are the camera and amp getting good power?
Are the spliced connections clean and dry?
Is the coax in good shape? Is it old?
--
David
dgminala at mediacombb dot net

Lost in VIDEO signal
 

On Jun 1, 9:29*am, "Dave M" wrote:
benitos wrote:
Hi ,

We have a CCTV cam (Bosh WZ18) that is 1500 feet from the LCD display.

The cable that was used is a RG59 and having 2 splices (2 junctions).

The video signal is poor , we can see tha image but with lines and
it's noisy.

Is there a way to improve or "rebuild" the signal ?

I tried a VID-AMP SPECO / PROVIDEO VID-AMP 1 IN / 1 OUT VIDEO
AMPLIFIER but did not help.

http://www.surveillance-video.com/vid-amp.html

A few questions to maybe lead you to the problem...
Do you have a good picture when the display is connected close to the
camera? *If not, then either the camera or the display is bad. *If yes, then
the coax or the splices might be bad. *Does the picture degrade when the amp
is connected?
Where do you have the video amp installed? *It should be close to the
camera; not the display.
Are the camera and amp getting good power?
Are the spliced connections clean and dry?
Is the coax in good shape? *Is it old?
--
David
dgminala at mediacombb dot net- Hide quoted text -

- Show quoted text -

Hi , it's a brand new cable. Splices are good. Signal at the CAM is
good. I cannot connect the AMP to the CAM side , only at the Display
side. That's an issue.

I thing the problem here is the lenght of the cable. Usually , RG6
would be better and less than 1000 feet. 1500 feet is very long.


Thanks

Lost in VIDEO signal
 

"benitos"

I cannot connect the AMP to the CAM side , only at the Display
side. That's an issue.


** How are you getting power to the camera ?

( runs on 12V DC or 24VAC at about 4 watts )



.... Phil

Lost in VIDEO signal
 

On Jun 1, 10:38*am, "Phil Allison" wrote:
"benitos"

I cannot connect the AMP to the CAM side , only at the Display
side. That's an issue.

** How are you getting power to the camera *?

* ( runs on 12V DC or 24VAC at about 4 watts )

... *Phil

I put 24VAC to the CAM now.

On DC12 , cable is too long ,was getting 6.5 volts to the CAM.

Lost in VIDEO signal
 

On Wed, 01 Jun 2011 09:11:57 -0700, Jeff Liebermann
wrote:

Intersil makes a line of video equalizer chips that will correct the
video signal for frequency dependent line losses:
http://www.intersil.com/video/
There are different chips for different for different lengths.
http://www.intersil.com/products/deviceinfo.asp?pn=ISL59601
http://www.intersil.com/products/deviceinfo.asp?pn=ISL59602
http://www.intersil.com/products/deviceinfo.asp?pn=ISL59603

I forgot the data sheet. Note the photos of the video quality:
http://www.intersil.com/data/fn/fn6739.pdf


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Lost in VIDEO signal
 

On Jun 1, 10:55*am, benitos wrote:
On Jun 1, 10:38*am, "Phil Allison" wrote:

"benitos"

I cannot connect the AMP to the CAM side , only at the Display
side. That's an issue.

** How are you getting power to the camera *?

* ( runs on 12V DC or 24VAC at about 4 watts )

... *Phil

I put 24VAC to the CAM now.

On DC12 , cable is too long ,was getting 6.5 volts to the CAM.

Putting an amp at the dislay end just amplifies signal plus noise, it
must be closer to the camera so that it only amplifies signal and not
noise.....

Lost in VIDEO signal
 

"Phil Allison" :

"benitos"

I cannot connect the AMP to the CAM side , only at the Display
side. That's an issue.

Putting an amp at the dislay end just amplifies signal plus noise, it
must be closer to the camera so that it only amplifies signal and not
noise.....

** Where is this mysterious extra noise coming from ??

The self noise of a 75 ohm source in a 5 MHz bandwidth ( circa 1uV ) is not
relevant to a 1 volt video signal.

The antenna problem, where one is dealing with uV level signals, is another
kettle of fish.



..... Phil

Lost in VIDEO signal
 

On Wed, 1 Jun 2011 20:18:06 -0700 (PDT), "
wrote:

Putting an amp at the dislay end just amplifies signal plus noise, it
must be closer to the camera so that it only amplifies signal and not
noise.....

It's not a S/N problem. It's the change in group delay across the
video frequency range that's distorting the parts of the NTSC video.
Throw in a -6dB/octave loss to trash the amplitude. See the photos
near the bottom of:
http://www.intersil.com/data/fn/fn6739.pdf

Instead of an adaptive equalizer, it can be done with a passive
equalizer, followed by an amplifier to compensate for the losses. The
adaptive equalizer adjusts itself, while the passive equalizer and amp
design requires level adjustment. When something changes in the
cabling, the levels need to be re-adjusted.

Typical video distribution amplifier:
http://www.multidyne.com/amps.html
Claims "3000 feet of Belden RG59U to within +/-0.05dB at 5MHz".
Probably overkill for a security camera.

This design works to 250ft. More amplifier gain will be required for
1500ft.
http://cds.linear.com/docs/Design%20Note/dn92.pdf

Here's another example. Claims 1000ft or mo
http://www.decadenet.com/cab/cab.html

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Lost in VIDEO signal
 

"benitos"

We have a CCTV cam (Bosh WZ18) that is 1500 feet from the LCD display.

The cable that was used is a RG59 and having 2 splices (2 junctions).

The video signal is poor , we can see tha image but with lines and
it's noisy.


** That sounds like you have a ground loop in the cabling passing noise into
the shield of the RG59.

Your 24VAC may well be the source.

Or possibly injection from AC power cables running along with the RG59.

Whatever, the pic should not contain noise or lines.



..... Phil

Lost in VIDEO signal
 

On 2 juin, 01:18, "Phil Allison" wrote:
"benitos"



We have a CCTV cam (Bosh WZ18) that is 1500 feet from the LCD display.

The cable that was used is a RG59 and having 2 splices (2 junctions).

The video signal is poor , we can see tha image but with lines and
it's noisy.

** That sounds like you have a ground loop in the cabling passing noise into
the shield of the RG59.

Your 24VAC may well be the source.

Or possibly injection from AC power cables running along with the RG59.

Whatever, the pic should not contain noise or lines.

.... *Phil

Right , there is a 400VAC passing near in the ground.

Is it possible to remove noise at the Display end?

Lost in VIDEO signal
 

"benitos"
"Phil Allison"
"benitos"

** That sounds like you have a ground loop in the cabling passing noise
into
the shield of the RG59.

Your 24VAC may well be the source.

Or possibly injection from AC power cables running along with the RG59.

Whatever, the pic should not contain noise or lines.


Right , there is a 400VAC passing near in the ground.

Is it possible to remove noise at the Display end?


** Find the cause and fix that.

If there is a common ground connection between the 24VAC and the RG59 -
that is it.

Co-axial cables are good at rejecting external magnetic field interference -
but may be subject to an AC electric field that runs alongside for 1500
feet.



..... Phil

Lost in VIDEO signal
 

On Jun 3, 2:50*am, "Phil Allison" wrote:
"benitos"
*"Phil Allison"
"benitos"



** That sounds like you have a ground loop in the cabling passing noise
into
the shield of the RG59.

Your 24VAC may well be the source.

Or possibly injection from AC power cables running along with the RG59.

Whatever, the pic should not contain noise or lines.

Right , there is a 400VAC passing near in the ground.

Is it possible to remove noise at the Display end?

** Find the cause and fix that.

If there is a common ground connection between the 24VAC and the RG59 -
that is it.

Co-axial cables are good at rejecting external magnetic field interference -
but may be subject to an AC electric field that runs alongside for 1500
feet.

.... *Phil

Perhaps a better 75 ohm cable like RG11 might help, but it will get
quite expensive. Lenny

Lost in VIDEO signal
 

On Jun 3, 2:50*am, "Phil Allison" wrote:
"benitos"
*"Phil Allison"
"benitos"



** That sounds like you have a ground loop in the cabling passing noise
into
the shield of the RG59.

Your 24VAC may well be the source.

Or possibly injection from AC power cables running along with the RG59.

Whatever, the pic should not contain noise or lines.

Right , there is a 400VAC passing near in the ground.

Is it possible to remove noise at the Display end?

** Find the cause and fix that.

If there is a common ground connection between the 24VAC and the RG59 -
that is it.

Co-axial cables are good at rejecting external magnetic field interference -
but may be subject to an AC electric field that runs alongside for 1500
feet.

.... *Phil

No , I did not ground the RG to the 24VAC