Sunday, October 23, 2011

Installing Compression Style Connectors to RG59/RG6 cabling

Installing Compression Style Connectors to RG59/RG6 cabling

1. Connectors are color coded for cable type. See chart below or manufacturer’s recommendation

2. Strip cable to dimensions shown on chart. Remove cable jacket and dielectric
3. Fold exposed braid back over cable jacket leaving smooth foil attached to dielectric
4. For Quad Shield Cable: Fold outer braid back over jacket, remove outer foil and fold inner braid back over jacket.
 5. Trim center conductor to proper length, see (A) dimension
6. Insert cable into rear of connector. Insertion depth is shown, on chart. For F-connectors, dielectric should be flush with support mandrel face.


Tips & Tricks:
  • The key to a good crimp is proper cable & connector preparation
  • When crimping other mfg’s connectors, minor adjustments to the crimp height may needed. Simply adjust adapter up or down
  • Keep adapters secured in tool to prevent loss

 Tools required: Side cutters, needle nose pliers, X-acto knife, a cable stripper and a BNC crimper.

The stripper is required because the different bands in the coax cable have to be cut precisely to different lengths and depths, and this is difficult to do without the proper tool.

The BNC Crimper is used twice in the process - first to crimp the BNC pin to the main conductor, and then to crimp the collar over the outer insulation at the end of the operation. A quality crimper can make the difference between a connection that works and one that has to be discarded.

It is also a good idea to make a length of test cable and try it out between a couple of computers on the system before actually going through the trouble of pulling cable through wall and ceiling spaces. You don't want to do all that hard work only to find you've got the wrong cabling! The connector itself consists of three parts: the connector itself, the center pin, and the crimp barrel.
STEP 1: PREPARE CABLE
Prepare the end of the cable with the cable stripper tool. Leave yourself a few extra feet of cable length for mistakes. If you get a bad connector, you'll be able to cut it off and try again.
Setting up the cable stripper may require some trial and error adjustment.
Leave about 1/4 inch of cable sticking out the front of the stripper. You then rotate the stripper about the cable until the two layers of insulation and the shielding are cut through to their proper depths.
The center conductor is about 1/2 inch long (it will be cut to fit). The exposed portion of the inner insulation band is about 1/8 inch and the braided shielding between the two insulation bands has been cut back cleanly to the same length as the outer insulation band.
If the cable stripper does not completely do its job, you may have to clean up the cable end with an X-acto knife or needle file. Care counts here. The center conductor should not be nicked, nor should any of the braided shielding be exposed - the most difficult part of this operation is to strip the shielding without damaging the inner insulation band.

STEP 2: CRIMP PIN
Fit the center pin from the connector package over the center conductor as far as it will go. The resulting length of exposed center conductor is the amount of conductor that will have to be cut off for a proper fit. Take the pin back off and cut the center conductor to the correct length with side cutter pliers. It should be 3/16 inch plus or minus. Now when the pin is placed back on the conductor, its base should just reach the inner insulation band (the center conductor should no longer be exposed.)
Place the pin on the center conductor, snug up the crimping tool over the pin (in the special die portion of the crimper provided for the pin) . . . and when you're absolutely sure everything is properly aligned, crimp the pin to the center conductor. Be careful. If this is messed up, you have to start over prepping the cable again with a new connector. Have a few more connectors on hand, even though you'll get good at this, mistakes are made, and if you don't have enough you'll put a real time strain on your project. You will use them!
The base of the pin is seated on the top of the inner insulation band. The crimping process flattens out the pin a bit where the crimping tool applies pressure to it. Clean up any sharp edges left by the crimper with a jeweller’s file, if necessary.

STEP 3: INSTALL BNC CONNECTOR
Slide the Crimp Barrel (or collar) over the cable before installing the connector itself - we will come back to the crimp barrel in the next step, but you have to slide it onto the cable now (you can't force it over the much larger connector later).
You must insert the connector unto the cable. The knurled cylinder portion fits over the pin and inner insulation band and is press-fitted-twisted into place. It has to fit snugly between the outer and inner insulation bands, and during the process, it fights with the braided shielding for this tight space.
When you think you've got the connector inserted under the insulation as far as it will go, push it a little farther. You'll know you're finished when most of the knurled surface has disappeared under the insulation and the center pin is rigid in its seated location inside the connector. If the pin is loose and the connector is on as far as it will go, the length of exposed inner insulation band when the cable was stripped is too short. If the pin is tight but a lot of the knurled portion of the connector is still showing, the length of exposed inner insulation band and/or center conductor when the cable was prepared is too long.

STEP 4: CRIMP BARREL
You're almost done. Now slide the crimp barrel (placed on the cable at the beginning of the last step) up as close to the connector as you can get it.
It will take some effort to get as much of it as possible over the bulge in the cable caused by the last step.
If you have a general-purpose wire stripper/crimper, it has an "ignition terminals" opening that is a little bigger than the cable and a little smaller than the crimp barrel. This is a great tool for putting some leverage behind the crimp barrel when easing it over the bulge in the cable.
Now you can crimp the barrel using the other, larger opening in the BNC crimp tool die. This will tighten and deform the crimp barrel down over the connector and cable for a secure connection.
Crimping the barrel should force the bulge in the cable up over what remains of the exposed knurled portion of the connector to the connector's base. Now you can install another connector on the other end, and then test the completed length of cable. It is good practice to test each length of cable as you go rather than install all the connectors and cabling, and then try to track down a bad connection. With a little practice you will be installing the BNC connectors like a pro.
Installing a Twist-on type BNC Connector

STEP1:
Use a stripping tool to strip the shielding from the coax part of the cable. In order for the connector to go on smoothly you will want about 3/4" of the center conductor showing and about the same amount of the copper wire braid showing (see figure 2 below).
STEP2:
 
Make sure that none of the strands of copper wire braid touches the middle conductor wire when you twist on the BNC connector. If they accidentally touch, this will not damage the camera but can result in a black (shorted out) image from the camera.
Twist on the BNC Connector onto the wire until it is snug. You will repeat Steps 1 - 3 for the DVR end of the COAX cable.





Installation of the 2 Piece BNC Crimp type connector

A crimp type connection allows for quick and simple installation while still maintaining a mechanical and electrical connection fairly close to a solder type termination. Some of the key points to remember are as follows: Make sure to use the proper size connector for the type of cable you are using. Make sure all cuts and stripping is clean. Avoid nicks as much as possible. Use the proper crimp tool; don't try to improvise with pliers, etc. Follow these steps.
 BNC connectors are not hard to install, but they must be installed correctly or they can cause problems down the road. Reproduced below are the instructions from Amphenol (the biggest connector maker). Here is a technique which requires no special tools other than a cable stripper and a crimping tool and which you may find easier than trying to measure the dimensions given in the Amphenol instructions below. You should have a look at the instructions from Amphenol , since some important warnings are contained in them, you may find an easier technique than what is described here.
 
  1. Place the Plug Body assembly on the work surface
  2. Place the male contact pin on the table with the tip of the pin aligned with the front of the plug assembly
  3. Place the cable next to the pin with the end of the cable just beyond the little hole in the side of the pin
  4. Carefully cut the cable outer sheath right where it lines up with the cable-entry edge of the Plug Body.
    Do this with a razor blade or knife being very careful not to nick or cut any of the shield braid wires.
    It's better to remove too little sheath than too much. You can remove more later if necessary.
  5. Slide the Outer Ferrule onto the cable
  6. Push back the braid to expose the inner conductor
  7. Using a razor blade or knife, cut off about 4mm (.156 in) of insulation from the end of the inner conductor.
    Again, be very careful not to nick any of the conductor wires.
    • If using RG62 cable (93 ohm) put the little bushing onto the center conductor as shown in the picture below. Bushing not needed for RG58
  8. Place the Male Contact Pin onto the inner conductor, making sure all wires are inside the pin. If the pin doesn't fit snugly against the insulation, remove it and trim the conductors until it does. NO INNER CONDUCTOR WIRES SHOULD BE EXPOSED
  9. Using the appropriate crimp tool (the gold-colored one for RG58, found in the "miscellaneous wrenches" drawer in RM 107) crimp the pin onto the inner conductor
  10. Push the Plug Body Assembly onto the cable until you feel it 'snap' into place. The end of the pin should be flush with the edge of the Plug Body. If you can't push it in far enough because not enough outer sheath was removed in step 4, trim a little more of the outer sheath off until the Plug Body goes all the way on and the pin snaps in. BE VERY CAREFUL AT THIS STEP THAT NO BRAID WIRES ENTER THE PLUG BODY. THIS CAN CAUSE A SHORT.
  11. Push the braid up over the Plug Body and trim it with a cutter or scissors so that it comes just up to the larger diameter part of the Plug Body. It should come all the way up over the knurled or ridged crimp barrel. Having braid wires stick out because they're too long is unsightly, but a greater problem is having them too short and becoming disconnected from the Plug Body.
  12. Slide the Outer Ferrule up over the braid and the plug body as far as it will go, then crimp it in place with the crimp tool.

Monday, October 17, 2011

Little about CCTV Guidelines for Identification

This article is now slightly out of date as the standard height of a person has now changed to 1.7m and the percentage for Identification of an Unknown Person is now 100% and not be 120% shown. Nonetheless, we believe this is one of the best articles available with regards to the technical background of this The Home Office Requirement.

Some time ago the Home Office issued guidelines for the identification of persons and vehicles. This is fine, but many system engineers stumble when trying to find what camera and lens combination will satisfy these guidelines. And what about end users who know even less about camera and lens formats, how can they assess the merits of competing specifications? This month all will be revealed for both groups.

Charts showing the horizontal and vertical fields of view for many lenses and four formats are given in ‘The Principles and Practice of CCTV’ and were published in the first issue of CCTV Today (Jan ‘94). They also show the % of the screen height of a 1.7M person. The Home Office guidelines had not been published for general use when I produced the first draft of the book and so the 1.7M was my guess at the average height. The current guidelines use 1.6M as the height.


The values for various degrees of identification are given as the percentage the 1.6M figure would occupy of the monitor screen. I call this the ‘screen height ratio’. The complete guidelines are provided in several Home Office publications and so only the basic ratios are given in this article. The publications are available free from the Home Office and provide a lot more information as well. 

These criteria are now becoming increasingly used as part of the specification for many CCTV systems, particularly in Town Centre schemes. Sometimes the specification will state the distance from the camera for each criterion, sometimes the specification will ask the question, ‘at what distances from the camera will the criteria apply’? In either case it involves calculations that are not too difficult but can be tedious to keep repeating for each lens and camera location.

Another problem that many people find difficulty in resolving are the different fields of view obtained from various camera and lenses formats, i.e. what is the result of fitting a 2/3" lens onto a 1/2" camera, and how does this affect the screen height ratio at certain distances? 

A word of caution, just about all lens manufacturers brochures give the HORIZONTAL angle of view, whereas these calculations require the VERTICAL angles of view. The vertical angle of view is the horizontal angle times 3/4. 

Field of view

Diagram 1 Field Of View
The field of view is the ratio of the sensor size to the focal length and the distance to the subject. This is shown in diagram1. The 'width to height' ratio of the sensor is 4:3. The horizontal and vertical angles and therefore fields of view are different and must be considered separately. 

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Note when using these ratios all the units must be the same, i.e. millimetres or Metres. 
Sensor Sizes
Diagram 2 shows the sensor sizes to be used when calculating fields of view and angles of view. 

Diagram 2 Sensor Dimensions
Example
Supposing it required to recognise a known person at 50M, using a 2/3" lens, the following is the calculation.
The scene height at 50M needs to be twice the standard height, 2 x 1.6=3.2M. Therefore:
The nearest standard would be a 10.5:105mm zoom lens to satisfy this requirement.
The formula can be worked backwards to find the scene height for a given lens. It is a simple matter to put all these criteria into a spreadsheet program and find the result for any combination. However, this may not be very convenient for the many salespersons on the road.

Saturday, October 1, 2011

NVR Software

First NVR software to feature instant video playback option. Search video by calendar, timeline, date, time, alarm event, or by file with simultaneous live view.. Add smart tags to video in real time for easy retrieval. Features step by frame, image export and playback speed functions. View recorded video from any remote site. Multi-Screen playback with pop out spot screen. Includes batch export for easy video archive & backup.

The new release introduces innovative features not found on other cctv software as well as several performance & usability enhancements.

- Support offloading of Video Analytics processing from CPU to GPU via Nvidia Cuda
- Digital Zoom on Live & Playback video
- Preview Sequence
- Preset Sequence
- Support Pelco-D Keyboard via RS232 / RS485
- Add Support for Pelco, Impath, IP Cameras
- Updated support for H.264 camera
- Support Secondary Port in Video Server
- Added On-Screen Keyboard Feature
- Added Smoke & Fire Detection Module
- Video Analytics & Fire Dectection are now purchased separately in per-channel license
- Pos function removed to seperate package

The addition of support for analogue PTZ keyboards means is the most compatible ip surveillance software on the market allowing users to support complete legacy analogue systems or build Hybrid systems without upgrading existing hardware infrastructure.