OK, first, I don't know for any fact that an RG58 coax cable is 75Ω. My question has to do with video cabling. I recently discovered someone has been peering through my windows at night. Not happy about that. AND they know where my one and only security camera is. So I'm going to install three more cameras to cover the perimeter of the home. The existing camera has a BNC connector that adapts to a 20 or 22 gauge twisted pair of wires (four sets of wires). One set brings 12 VDC to the camera, another set carries video back to the DVR. The camera is a good quality camera but what is reaching the DVR is not so great quality. I'm thinking about getting some coax cable to conduct the video signal back to the DVR. But I don't know what 75 ohm means. 75 ohms - that's a lot per foot, and I don't think that's what it means. So my question revolves around coax cables that are rated in ohms of some sort. What do they mean and why (or not) would (or wouldn't) I use coax as opposed to the silly twisted pair?

 

Hello,

The given 75 Ohms is the cable impedance.

RG58 is an 50 Ohms cable.
RG59 is an 75 Ohms cable.

Just have a look at the wiki page:
https://en.wikipedia.org/wiki/Coaxial_cable

Bertus

 

hi,
What are the lengths of your video cable runs.?
E
EDIT:
This PDF may help in identifying the BNC type and impedance.

 

The characteristic impedance of the video cable is 75Ω.
This is the impedance of a infinite length of cable, when measured with an AC signal, due to it's distributed capacitance and inductance (not ohms per foot).
If a finite length cable is terminated with a 75Ω resistance then it will look like a 75Ω resistance from the other end.
It is not the DC resistance, which is very low per foot.

 

What are the lengths of your video cable runs.?

I'm estimating that two runs will be approximately 70 feet each with the other two runs to be around 50 feet.

From what I read from the post by @bertus I'm assuming I'd want a 75Ω coax. I have a bunch of coax from the local cable company that was cut out some time ago. It's a dual run with a ground wire running the length. It is my assumption that I can use the dual run for two video feeds, utilizing the shield as the negative leg of the power supply and use the external solid copper wire (intended for ground) as my 12 volt positive to the two cameras. These two cameras will be mounted at the peak of my roof, one camera facing down the driveway the other facing up the driveway. One will cover the entrance door while the other covers the garage door.

The last thing I want to do is make fundamental mistakes by assuming things. I know here someone will quickly point out where I may be going wrong and redirect me in the right direction. The coax I have is not marked 58 or 59. It is foam core construction with a foil shield wrapped in a cheap beaded shielded outer layer, covered in vinyl or plastic of some sort.

 

Hello,

Most cable used by a cable company is 75 Ohms.
There are many different qualities of coax cable.
The best will have a foil with a braided mesh as outer shell.
The next best is two layers of braided mesh.
The worst is a single braided mesh.

Bertus

 

hi,
My 3, CCTV security camera's have 20mtr runs, the cable is a pair of screened cable, one pair for video and one for the 12Vdc supply.
One end of the cable is, at the camera end is a BNC, the other end the video cable is a phono plug/socket.
The twin screened cables are approx 3.5mm in diameter.

The termination is a Hard drive DVR [ and replay ] recorder, for 4 channels.
I am using the DVR HDMI output to a TFT TV monitor input, the picture quality is excellent.

Have you tried to test the picture quality over a very short cable, it maybe your DVR.

The camera's have IR night vision illuminators, in addition I have added 2 more IR illuminators.

E

 

hi,
My 3, CCTV security camera's have 20mtr runs, the cable is a pair of screened cable, one pair for video and one for the 12Vdc supply.
One end of the cable is, at the camera end is a BNC, the other end the video cable is a phono plug/socket.
The twin screened cables are approx 3.5mm in diameter.

The termination is a Hard drive DVR [ and replay ] recorder, for 4 channels.
I am using the DVR HDMI output to a TFT TV monitor input, the picture quality is excellent.

Have you tried to test the picture quality over a very short cable, it maybe your DVR.

The camera's have IR night vision illuminators, in addition I have added 2 more IR illuminators.

E

Sounds like your setup is virtually the same as mine. Only difference is I have twisted pair cables for power AND for video. And my quality - well, it leaves room for improvement. Like you, I have a TFT monitor and a 4 channel HD DVR. Mine is capable of audio capture as well, though I don't intend to install microphones.

 

It's likely RG-6 or RG6-QS (Quad Shield). the latter has a bigger OD.

The connectors are different. Siamese cables were used in the satellite industry without the ground.

I like the compression connectors. This https://www.homedepot.com/p/Ideal-R...ssion-F-Connector-Pack-of-50-92-650/202309350 is indoor/outdoor and compatable with both cable types. Not all are. You need a tool for the compression connector.

Post a pic, with the end dissected and with something of a known dimension (drill bit), ruler to get the diameter optically.

Then there is the unusual use of coins: https://mdmetric.com/tech/coinmeasure.htm

 

Cables have typical compression F-Type connectors. I've used a lot of it for jumpers from the wall to the TV, the VCR (remember those?), and other assorted F-Type connected devices. My one and only (at present) camera has a BNC connection with a connector with a box on the back of it with two screw terminals for cabling. I'm assuming they are some sort of line matching transformer, (LMT) similar to the LMT's on standard TV antennas connected via coax cable. I could post a picture, could give you a measurement in thousandths of an inch (convert to metric if necessary), but for now the cable is just the standard stuff. And I have a bunch of those compression F-Type connectors AND the crimper used for sliding the collet inside the body to fasten the connector.

Right now I'm dinking around with the smoke detector. They're interconnected and AC powered. One is not showing AC power even though there's power at the connection. It looks like the plug on the detector has some kind of film on the pins. Different issue. Off topic. No help needed with them.

 

You can also get BNC connectors with the 75 ohm characteristic impedance and I think with compression tooling. A BNC for RG6 would be 75 ohm.

 

Not to veer this thread off course, but I'd like you to know that a few months ago I bought a Ring system camera from Amazon, and I'm quite pleased with its performance. The system is not too expensive, works through WiFi, and lets you check its state wherever you might be by using your smartphone. The characteristic that had me sold was that it can be programmed to identify if people are within its visual frame at certain hours, and it has a speaker through which you can talk or warn them if you think it necessary.

 

hi Tony,
A few non technical operational problems you may encounter.

1. Don't mount a IR security camera pointing out thru a window, the IR back scatter from the glass will blot out the night image.

2. Spiders webs at night when illuminated with IR, glow like fluorescent tubes and obscure the image.
Choose a mounting point where you can easily clean the camera glass.

3. Rain, snow and heavy mist reflect the IR, result is a poor nite image.

4. If you use the visual intruder alarm sensor on the DVR software, at night every flying insect, moths etc glow like a Boing 747 and will drive you crazy with false alarms.
The listed weather events in item #3, will also trigger the alarms.

5. If you use additional IR illuminators, build a simple Nite/Day LDR circuit, reduce operating costs and improves IR lifetime.

6. If the camera's and IR are rated at 12Vdc, under run them at approx 11Vdc, increases their lifetime.

7. I have one camera mounted in upstairs room looking thru a window
To get around the problems in item #1, I used black tape tape to cover the IR section of the camera glass, not the LDR part.!
The additional outdoor IR illuminators are enough to give a very good nite image from this indoor camera.

8. As I use only 3 camera's into the 4 channel DVR, I have connected my TV satellite into 4th DVR input. So if required I can watch TV...

E

 

#1 (through a window): I have no intention to do so. In part - for this very reason.

#2 (spider webs): Yup. See that often enough. In fact, it's quite interesting to see a spider on the lens of my camera. Like so many 50's and 60's SiFi movies about giant spiders. Freaks my wife out big time too.

#'s 3 & 4 (false triggers): Yeah, I get triggers from snowflakes, from steam from the dryer when the wind blows it past the camera, tiny bugs as big as dogs, birds eating said giants. Shadows of birds on the driveway trigger recordings too. Another thing that reduces camera efficiency is when you park a car under the camera and there's a full moon. You get this bright glaring spot reflected back at the camera. On moonless nights, the reflectors on the back and sides of the cars also reflects back like a beacon.

#5 (illuminators): Had my neighbor install one in her yard (elderly widow) so my camera could see if someone was in her yard. Has proven useful for both identifying who was the owner of the dropped screwdriver (attempted break-in) and makes her feel more secure. I said it makes her FEEL more secure.

#6 (11 VDC): This is new to me. I would have to modify the power supply to do that. Don't know if that's going to yield any real benefits as the camera that is in operation now has been in operation for 5 years thus far. The only failure I've experienced with it was the power going TO the camera, the cable failed.

#8 (satellite TV): I'd like to know how you did that. For the longest time I've wanted to record live TV broadcasts from my antenna and be able to play them back at a later time. Also to be able to fast forward through commercials in recorded content. But I'd use a separate DVR for that. Otherwise broadcasts would eat up the disk space in no time. I would imagine that a TV tuner would also be necessary.

@ericgibbs Thanks for the good advice. Much appreciated.

 

Excellent points.

hi Tony,
A few non technical operational problems you may encounter.

1. Don't mount a IR security camera pointing out thru a window, the IR back scatter from the glass will blot out the night image.

2. Spiders webs at night when illuminated with IR, glow like fluorescent tubes and obscure the image.
Choose a mounting point where you can easily clean the camera glass.

3. Rain, snow and heavy mist reflect the IR, result is a poor nite image.

4. If you use the visual intruder alarm sensor on the DVR software, at night every flying insect, moths etc glow like a Boing 747 and will drive you crazy with false alarms.
The listed weather events in item #3, will also trigger the alarms.

5. If you use additional IR illuminators, build a simple Nite/Day LDR circuit, reduce operating costs and improves IR lifetime.

6. If the camera's and IR are rated at 12Vdc, under run them at approx 11Vdc, increases their lifetime.

7. I have one camera mounted in upstairs room looking thru a window
To get around the problems in item #1, I used black tape tape to cover the IR section of the camera glass, not the LDR part.!
The additional outdoor IR illuminators are enough to give a very good nite image from this indoor camera.

8. As I use only 3 camera's into the 4 channel DVR, I have connected my TV satellite into 4th DVR input. So if required I can watch TV...

E

#2 I use a 'Orange Lysol' type spray on a long 'CCTV mop' to keep the spiders away. The best remedy is your external IR illumination trick with internal IR disabled. Without the tasty bugs attracted to the camera IR the spiders don't move in.

I never use and would never recommend wireless cameras for a Permanent security system beyond a wireless entry camera.

 

I never use and would never recommend wireless cameras for a Permanent security system beyond a wireless entry camera.

Have been avoiding wireless because of fears of hackers. Of course, I have no intention to install cameras inside the home, as my wife and I are both known to move about the house au-natural.

I've seen a floodlight IR system that also (or incorporates) a camera connected to my cell phone. The one I've looked at so far has the added feature of a microphone and speaker so I could warn a trespasser "Warning! You have been detected by an automatic security system. Do not attempt to move. Sit quietly and await the arrival of authorities or you WILL be vaporized." Actually, many many years ago I saw a commercial of such a nature. Of course they weren't advertising a security system that could vaporize an intruder, but I sure did get a kick out of it. Sort of like the James Bond car security system. Break in and the car explodes.

 

hi Tony,
My Satellite TV input to the DVR, is via my SKY subscription system box.
E

 

@ericgibbs My DVR is just a box with four BNC connectors on the back as well as four audio jacks. Without a video signal from a tuner I can't connect the DVR to a TV (of sorts). The commercially available DVR's all require a subscription (I think. Don't know if that's changed). But DVR's and TV's are a bit off subject. Maybe a discussion for a later thread. Or maybe someone has already covered that topic. For now I just want to be sure I go the right direction.

I'm leaning toward BNC on RG59 from the camera to the DVR. Power will be via a separate line.

My DVR has an alarm feature that I choose not to utilize because of all the false triggers due to snow, bugs and birds. The "Person Detection" circuit - that I like, but I'd have to start over with a system. And again, I prefer hardwired over wifi.

 

hi Tony,
I will watch out for your other thread.
I built a stereo dual PIR unit for people, raises an audible alarm and illuminates a bright LED, which can be seen on the DVR image record.
Helps with synchronising the alarms with the DVR timed record.
E