CCTV Camera Selection, Placement, and Analog/IP Signal Pathways

CCTV Camera Selection, Placement, and Analog/IP Signal Pathways

Why Camera Choice and Placement Matter

A surveillance system is only as effective as its weakest angle. Poorly placed cameras, undersized lenses, or badly terminated cables produce blurry, artifact-ridden footage that is useless for identification or evidence. This lesson covers how to choose the right camera, calculate coverage geometry, route and terminate cable correctly, and commission a live image you can defend to a customer or inspector.

Camera Types

Dome cameras mount flush to ceilings or walls and are vandal-resistant. Their low profile makes the direction they point less obvious, which can deter tampering. Use them in retail aisles, lobbies, and corridors.

Bullet cameras are cylindrical housings that project from a surface. They are easy to aim, handle longer focal-length lenses well, and signal their presence clearly — a deterrence benefit. Use them for parking lots, building perimeters, and long-distance monitoring.

PTZ (pan-tilt-zoom) cameras motorize all three axes and can follow movement, but they require a controller and power for the motor. A PTZ watching one target may miss another, so fixed cameras should cover critical zones while a PTZ covers wide open areas.

Analog vs. IP cameras: Analog cameras output a composite or HD-over-coax signal (HD-TVI, HD-CVI, AHD, or legacy CVBS) to a DVR (digital video recorder). IP cameras encode video internally and stream over Ethernet to an NVR (network video recorder). IP cameras offer higher resolution and flexible networking but require IP address management and a PoE switch or injector.

Field of View and Lens Selection

The angle of view a lens produces depends on its focal length and the sensor size. Manufacturers publish the horizontal angle of view (HAOV) for each lens-sensor combination. A shorter focal length gives a wider angle; a longer focal length narrows the view but covers greater distance.

For a rectangular room, use the following relationship to estimate how much horizontal width a camera covers at a given distance:

> Coverage width = 2 × D × tan(HAOV / 2)

Where D is the perpendicular distance from camera to the far wall and HAOV is in degrees. If coverage width is less than the room width, you need multiple cameras or a wider lens. Mark blind spots on your floor plan and reposition cameras until all zones — especially entry/exit points, cash registers, and storage doors — are covered.

Mounting height affects both coverage area and face-capture quality. For identification, cameras should be mounted between 8 and 10 feet high so the lens angle captures faces rather than the tops of heads. Aim the camera slightly downward so the field of view intersects the subject at head height.

Coaxial Cable (RG-59) — Routing and Termination

RG-59 is the standard coaxial cable for analog CCTV. It carries video on its center conductor and uses the braided shield as a ground return. Runs should be kept under the distance limits recommended by the camera and DVR manufacturer to avoid signal loss.

BNC crimp termination steps:

1. Strip the outer jacket carefully — do not nick the braid.

2. Fold the braid back over the jacket (crimp-style) or compress it (compression-style).

3. Trim the dielectric insulator to expose the center conductor.

4. Insert the cable into the BNC body; the center conductor must protrude through the pin.

5. Crimp the barrel and pin with the correct die size.

6. Test continuity and check for shield shorts with a cable tester before routing the cable inside a finished wall.

Safety: Wear safety glasses when drilling. De-energize any circuit before fishing cable near electrical wiring. Follow lockout/tagout (LOTO) procedures if working in an electrical panel area. Never route low-voltage cable in the same conduit as line-voltage wiring unless the cable is rated for it.

CAT6 Cable — Routing and Termination

CAT6 carries IP video, PoE power, and control data. Terminate with RJ-45 connectors using the TIA-568B wiring standard unless the site uses 568A consistently throughout. Maintain pair twist as close as possible to the connector — untwisting more than necessary degrades performance. Test each run with a cable tester that checks wiring map, length, and pair integrity.

Power over Ethernet (PoE): Many IP cameras draw power from the network switch through the CAT6 cable. Check the camera's PoE standard (802.3af or 802.3at) and confirm the switch or injector supports it before connecting.

Live Camera Commissioning

Once cable is run and terminated:

1. Connect the camera to the DVR or NVR.

2. For analog: confirm the DVR detects a signal on the correct channel; adjust focus ring and iris (if manual) until the image is sharp.

3. For IP: assign a static IP address or confirm DHCP assignment via the camera's web interface; set resolution, frame rate, and compression (H.264 or H.265).

4. Use a lux meter to record the ambient light level. Compare it to the camera's minimum illumination specification. If scene lux is below spec, add lighting or switch to a camera with IR illuminators or a lower minimum lux rating.

5. Record all settings, cable test results, and image quality observations on the commissioning checklist. Note any corrective action taken.

Safety Summary

• Wear safety glasses when drilling or fishing cable.
• Use insulated tools when working near energized equipment.
• Apply LOTO before accessing electrical panels.
• Keep work areas clear of tripping hazards from cable reels.
• Do not exceed ladder rated load; use a fiberglass ladder near electrical sources.