CCTV at farm gate

[Wazrus]

I'm in the process of fixing up my driveway/road - the LED lights for which I've sorted out, thanks to Tractor By Net, but the gate TV is giving problems.
I have a 100m (330ft) RG6 co-ax cable run and my 'setup' doesn't seem to like a run quite as long. Everything works well (camera, monitor, cabling) with short runs, but when I hook in the 100m RG6 co-ax, I get a 'no signal' message on the monitor. I have a CATV amplifier, which I've tried at both ends of the cable run, for another 'no signal' message I've checked the co-ax for continuity and it's OK., as are all the other connections. Connections are all crimped BNC, using the proper cable crimping tools.
The camera is a Samsung SDN500. The amplifier is a 'Seebest' (Chinese) "CATV signal amplifier" (quote), which could conceivably be entirely the wrong 'thing'. I'm no electronics 'type'!!
Perhaps I'm on the limits of a 'wired' setup?? It seems to me though, that there are runs far longer than mine, i.e., in apartment blocks, or do they prefer wireless? Maybe wireless is the way to go, but from my (very) limited experience, 'wired' is preferable. Any thoughts from the membership???
Thanks
Wazrus Australia

 

[KTurner]

100m should be fine for RG6. Does the setup work when using the amplifier with the short run of cable? Did you check the coax for resistance between the center conductor and shield? With nothing hooked to the other end, this should be open. Is this a new setup or has this worked in the past with the same cable? Do you have any splitters or does your amp have more than one output? If yes, put a terminator on any unused outputs.

Keith

 

[MikeInEburg]

A standard CCTV camera produces baseband video. A CATV amplifier is used for modulated video. They are incompatible.

That said, a camera should work fine on 100 meters of coax without amplification. How are you powering the camera? 100 meters of 16 or 18 AWG between camera and power supply would definitely be a problem.

 

[stingray1]

I'am with Mike I feel the problem is probably with the wire size and/or the power supply. The coax should be o.k.

 

[Wazrus]

Keith and Mike and Stingray

Thanks for taking the trouble, chaps

The power supply for the camera will be close by - i.e, about 5 feet away, (I have mains 240v power at the gate) so I don't think there's a problem with any losses due to cable run. My 'test' - before pulling the coax through the conduit - was to lay out 100m of coax on the ground, camera one end, monitor the other and all I had was the dreaded 'no signal'. Camera power was about 5 feet away.
The short run of cable worked just fine: clear, steady picture. Power again 5 feet away from camera.
The pundits here in Australia came down 50-50 as to whether there'd be problems with the 100m run, so I installed the amplifier - the wrong one ( thanks, Mike) - but with or without it, still there was 'no signal'.
If you all don't mind, I'll keep you posted with my bumbling around, and I will check the resistance as suggested. I will also lay out the coax in a straight line, instead of an 'out-and-back' loop and I'll also chop off the BNC connectors and do 'em again.
The whole thing is part of an exercise to remote power my gate, install LED lighting on the road and generally spiff up the front entrance. By the way, there'll also be another TV camera, but it'll be one of those bollard-mounted video doorphones, or something similar. (Hard to a doorphone for outside use) You really don't want to know what the 'experts' wanted to charge for the whole show: it certainly makes the bumbling about worthwhile and thus this thread.
Thanks once again for your input(s), Tractor-By-Net is the goods!
Wazrus Australia

 

[Wazrus]

Hard to FIND a video doorphone for outside use. Left out 'FIND' didn't I?
Wazrus Australia

 

[Wazrus]

Mike, Keith and Stingray
G'day from the other end! I mentioned I'd keep you posted with my bumbling with the CCTV and it seems I'm over the 'no signal' hurdle. Having changed all the connections to compression type and with the (absolutely) correct compression tools, the dreaded 'no signal' re-appeared.
At a loss as to exactly what to do next, I took the last resort and that was to lay the RG6 out 'straight', i.e., no 'loops', hook it all up - again - and bingo! Clear, steady picture.
When I mentioned 'loops', they weren't in just a jumble of cable on the ground, but a fairly carefully set up 'out and back', 50m cable out to the gate, 50m back, with just one return loop, no joints. Possibly, too, there might have been some interference from underground (1m down) power cables which were crossed twice. However, your guess is as good as mine: perhaps there's some pratical explanation, but it all seems to me to be a bit strange.
Anyway, thanks again for your input(s)
Wazrus

What's the difference if the cable's out straight or looped 'out and back'??

 

[MikeInEburg]

I'm not sure that I understand... What is carried on the "out" segment? I would think you would have camera to coax to monitor - requiring only one segment of coax.

 

[k0ua]

Mike, Keith and Stingray
G'day from the other end! I mentioned I'd keep you posted with my bumbling with the CCTV and it seems I'm over the 'no signal' hurdle. Having changed all the connections to compression type and with the (absolutely) correct compression tools, the dreaded 'no signal' re-appeared.
At a loss as to exactly what to do next, I took the last resort and that was to lay the RG6 out 'straight', i.e., no 'loops', hook it all up - again - and bingo! Clear, steady picture.
When I mentioned 'loops', they weren't in just a jumble of cable on the ground, but a fairly carefully set up 'out and back', 50m cable out to the gate, 50m back, with just one return loop, no joints. Possibly, too, there might have been some interference from underground (1m down) power cables which were crossed twice. However, your guess is as good as mine: perhaps there's some pratical explanation, but it all seems to me to be a bit strange.
Anyway, thanks again for your input(s)
Wazrus

What's the difference if the cable's out straight or looped 'out and back'??

There isn't any difference.. and the underground power cable should not matter either. This is coax we are talking about here. No in my estimate you have a defective piece of coax. with an intermittent break in it. When you move it around, you make and break the continuity. It is either still the connectors, or the coax itself is broken in the middle somewhere. That is all I can think of. If some of them time the signal is great, thru this coax and some of the time it is not, then the coax connection is intermittent.

James K0UA

 

[joshuabardwell]

There isn't any difference.. and the underground power cable should not matter either. This is coax we are talking about here.

Right. The whole point of coax is that the conductor is electrically shielded from the outside. Coax is very resistant to electrical interference. Either the run is too long and signal from the camera is too weak, or you have bad connectors or a bad run of cable. Given that you re-crimped the connectors, it's probably the cable--as silly as that sounds, I know, because what could go wrong inside a spool of cable?

Have you tried testing continuity through the cable? If you do this, do it while a helper wiggles and jiggles the cable all along its length. See if the continuity is interrupted at any point.

But, frankly, given the cost, I might consider just buying another run of RG6. If it fixes the problem, great, and if not, well, you'll probably use it somewhere, and at least now you know the problem isn't the cable.

 

[sparc]

I agree the coax itself should be your focus at this point.

 

[Wazrus]

I agree the coax itself should be your focus at this point.

From Wazrus
The consensus seems to be that the coax is indeed faulty and as suggested, I might try to take it back to the reseller. Having said that, I've tested it for continuity and it seems OK and as has been discussed, I reckon I've become pretty expert at fitting the compression connectors.
It seems I didn't explain my 'test' setup very well, such as it was.....Well, before pulling all the cable runs through the existing conduit and as a test, I unwound all 100m of coax on the ground. I simply laid it out: 50m on the way out to the gate, 50m on the way back, leaving it in a wide 'loop' and leaving the two runs of cable about 2-3m apart and connected the ends to camera and monitor. Nothing exact or remotely scientific about any of it.
Those two (out and back) runs crossed and re-crossed the underground supply I mentioned earlier, thus my thought that perhaps the U/G supply was interfering with the signal. That seems not to be the case, if I understand you all correctly.
As a last resort, I then re-arranged the test setup as a 'straight' run of cable, i.e., no loops anywhere, simply straight from camera to monitor, no bends, no connectors except at the camera and monitor, 100m straight, with camera power supply very close to the camera. Bingo! Pictures!!!
I could stand corrected, but it seems a matter of actual practice that one might avoid any 'looping' of coax carrying CCTV signals, or any situation where the same signal is in coax close by. That's my 'hypothesis'....:laughing:
Thanks once again for all your input(s)
Wazrus
PS If you're interested, I'll keep you posted on progress - or lack of it!!

 

[weedpharma]

Wazrus, are you planning to bury the coax? I have a roll of "cable tv" coax (can't find secifications) that I was going to do similar thing. I was woried about burying the cable in regard to corrosion.

Anyone have any knowledge about direct burying coax?

Weedpharma

 

[k0ua]

Wazrus, are you planning to bury the coax? I have a roll of "cable tv" coax (can't find secifications) that I was going to do similar thing. I was woried about burying the cable in regard to corrosion.

Anyone have any knowledge about direct burying coax?

Weedpharma

the cable must be rated for direct burial or it will deteriorate pretty quickly underground.. how fast depends some on your soil moisture conditions, but all coax jackets are not the same.. If rated for direct burial, it will be fine if not... It will NOT be fine. Find the data sheet on this brand and model of coax you have. They are usually published on the manufacture's website.

James K0UA

 

[k0ua]

From Wazrus
The consensus seems to be that the coax is indeed faulty and as suggested, I might try to take it back to the reseller. Having said that, I've tested it for continuity and it seems OK and as has been discussed, I reckon I've become pretty expert at fitting the compression connectors.
It seems I didn't explain my 'test' setup very well, such as it was.....Well, before pulling all the cable runs through the existing conduit and as a test, I unwound all 100m of coax on the ground. I simply laid it out: 50m on the way out to the gate, 50m on the way back, leaving it in a wide 'loop' and leaving the two runs of cable about 2-3m apart and connected the ends to camera and monitor. Nothing exact or remotely scientific about any of it.
Those two (out and back) runs crossed and re-crossed the underground supply I mentioned earlier, thus my thought that perhaps the U/G supply was interfering with the signal. That seems not to be the case, if I understand you all correctly.
As a last resort, I then re-arranged the test setup as a 'straight' run of cable, i.e., no loops anywhere, simply straight from camera to monitor, no bends, no connectors except at the camera and monitor, 100m straight, with camera power supply very close to the camera. Bingo! Pictures!!!
I could stand corrected, but it seems a matter of actual practice that one might avoid any 'looping' of coax carrying CCTV signals, or any situation where the same signal is in coax close by. That's my 'hypothesis'....:laughing:
Thanks once again for all your input(s)
Wazrus
PS If you're interested, I'll keep you posted on progress - or lack of it!!

Yes, but have you checked it for continuity while moving the coax with a helper? That is the very thing you must do. This is the only explanation for why when you loop the coax back and have your test setup all in one place the coax fails and when you stretched it out it worked OK.. the coax must be faulty, and your act of moving it caused the break in continuity. I should not mater a bit if the coax was rolled up in a 2 foot roll, it should perform the same, as long as the minimum bend radius was not exceeded.. and we are talking about 4 to 6 inches here for a minimum bend radius that would cause the center conductor to migrate thru the dialectric (the center insulation) into the shield. I realize you do not have nor probably have any access to a Time Domain Reflectometer, but you surely have an ohmmeter or continuity checker of some kind. If you had one with a buzzer or beeper you could short center to shield on one end and ohm or check the other end and wiggle/move the coax until the open manifested itself. Then remove the short on one end and move the coax and connectors and make sure there is no continuity from center conductor to shield and then repeat this procedure from the other end (to make sure you do not have a compound problem). I am betting you have a coax problem.

James K0UA

 

[JoeL4330]

you already can reproduce the "fault": no signal when there is a (particular) bend in the coax. Set it up so you get the dreaded "no signal" and then check continuity. Consensus seems to be that were you to that you would find a continuity fault.

 

[nikdfish]

Any chance you can borrow or rent a time domain reflectometer or get someone who has one to help out? Network cabling folks use them to ID & pinpoint faults in twisted pair & coax. Use of one can actually provide information on the precise distance from the connection to the fault (if there is one) when you are in a "no signal" condition.

Nick

 

[joshuabardwell]

Any chance you can borrow or rent a time domain reflectometer or get someone who has one to help out? Network cabling folks use them to ID & pinpoint faults in twisted pair & coax. Use of one can actually provide information on the precise distance from the connection to the fault (if there is one) when you are in a "no signal" condition.

Nick

Would that be overkill? I mean, to rent a TDR might cost $1000; another few hundred feet of RG6 is going to run $100 at most. I think Joel is onto something: put the cable back into the "no connection" state, use alligator clips or whatever to bridge the conductor and the ground at one end, and test for continuity between conductor and ground at the other end. If you have continuity, you know the cable is good--but I bet you don't have continuity.

 

[Wazrus]

Weedpharma: Me too! Farming weeds is a growth industry here, too!
The coax I'm using is specified as RG-6/U quad shield: it's branded CRG60E 75 OHM RG6U QUAD SHIELD CATV/MATV/SMATV 11-05-28-0109 047M. It's the goods, as far as I can make out, but that doesn't imply that it's perfect, as many of the posts re my CCTV cabling point out.
From a bit of preparatory reading, Gary Cratt (an Aussie satellite TV guru), suggests there are a few good reasons why you shouldn't bury your coax directly. A few quotes from Cratt's text in his book The Practical Guide to Satellite TV., 7th edition, ISBN 0 646 30682 0; Pages 47 and 48: "RG6-U is often silicon flooded to ensure moisture cannot penetrate either between jacket and braid, and has two layers of aluminium foil sandwiched between two layers of tinned copper braid" and: " Experience dictates that only RG-6/U cable with foam dielectric is suitable for TVRO installations. Cable having a 'honeycomb' air dielectric may have slightly lower (electrical/signal) loss (my brackets), but the risk of moisture entry and retention in the honeycomb structure far outweigh this factor"....
Further: "Once moisture enters a coaxial cable, it can be drawn by capillary action for many metres, causing the braid to corrode and eventually break down"...
More: "For longer runs, heavy-duty cable, called quad shielded RG11 should be used"...
For my money, the cost of conduit far outweighs the pain in the neck factor of having a direct-buried coax run fail due to moisture. My RG6-U will be in rigid PVC conduit, with the ends well and truly 'siliconed' to keep the water out! Partly for reasons of moisture rejection, I've gone to compression-type connectors, as it seems that the crimp-style connectors can allow moisture ingress.
Sorry about the long-winded reply, but I'd suggest you not direct bury your coax and I think those far more knowledgeable than me would say the same. And I'd suggest checking the specs of the cable you propose to use. Also, my 100m of coax cost $A44 and I don't reckon that's a lot of $, even if I have to replace it. It's not underground yet!
Good luck!
Wazrus

 

[joshuabardwell]

Sorry about the long-winded reply, but I'd suggest you not direct bury your coax and I think those far more knowledgeable than me would say the same.

Everything you say is true, but if the cable is rated for direct-burial, then you can direct-bury it--obviously. I think what you're saying is relating to garden-variety RG-6. Here's an example of direct-burial RG-6:

Direct Burial RG6 Coax Cable for Cable TV 'Flooded' CommScope

You can just trench and stick that stuff right in the ground. You may also need special connectors to keep water out.