Introduction
This article summarizes common problems encountered with outdoor surveillance cameras. Outdoor cameras are often used with digital video recorders (DVRs), so many issues occur in the interaction between cameras and DVRs.
1. New cameras from the same manufacturer are not found by an older DVR
First check the camera power wiring. If the camera uses a separate power supply, wait about 20 seconds after powering the camera, then cover the lens to block light and observe whether the infrared LEDs light up. If they light, the power is likely OK. Next check the network cable: observe the camera tail lights and the switch port lights. If they do not blink, try a different cable (even if the cable is good, pinout differences between vendors can cause issues).
If those checks pass but the DVR still cannot detect the camera, the DVR and camera may be on different subnets. Try a fixed IP search in the network settings and then change the camera IP to match the DVR subnet after detection. At this point, request the vendor's PC client discovery tool and connect a PC to the switch to perform a fixed IP search. Once the camera is found, modify its IP accordingly.
2. Cameras and DVR from different manufacturers are not found
Different brands often use proprietary protocols. Interoperability typically relies on ONVIF, which most brands support. If hardware and wiring are confirmed good, common causes include:
- Some models, for example Hikvision IPCs upgraded to firmware V5.5.0 or later, have ONVIF disabled by default. You must enable ONVIF and set an ONVIF administrator account for other-brand DVRs to discover and add the camera. Check with the vendor.
- The device may not support auto-configuration and may have a factory IP in an unusual range such as 170.x.x.x. Ask the vendor for the PC discovery tool.
3. DVR shows the camera but there is no video
Common situations include:
(1) Main stream has no image because the bitrate is too high
It is common for the main stream to show no image while the substream does, or for both streams to show no image. Log into the camera management interface from a PC and reduce the bitrate.
(2) Camera uses H.265 while DVR supports only H.264
Change the camera encoding to H.264 in the management interface and consider lowering the bitrate.
As with consumer cameras, avoid indiscriminate firmware upgrades on cameras and DVRs.
Signal and Power Faults
1. Large-area moire or mesh patterns destroying the image
Often caused by short or open between the video cable core and the shield. This usually appears only on channels with poor connectors such as BNC. Inspect and repair connectors on affected channels.
2. Device faults caused by incorrect power
Possible causes:
- Incorrect power wiring or voltage.
- Insufficient power capacity or undersized conductors causing voltage drop.
- Transmission line short, open, or transient overvoltage.
Because incorrect power or transients can damage equipment, verify and inspect the power system thoroughly before commissioning.
3. A horizontal black or white bar slowly scrolling up or down on the monitor
Determine whether the cause is power or cabling. On the control unit, connect a single known-good camera nearby. If the interference does not appear, the control unit is likely fine. Then use a portable monitor to check each front-end camera output in turn.
4. No image on the monitor
Check whether the power supply or the camera is damaged and whether wiring is continuous. Replace the power supply to test. If the camera is faulty it usually requires factory repair.
5. Dirty switching between images on the main unit
Symptoms include residual overlap from other channels or line-sync interference after switching. This is typically caused by poor-quality switchers or matrix switches that do not provide sufficient isolation. In RF transmission systems, excessive intermodulation or crosstalk may be to blame.
6. PTZ (pan-tilt-zoom) unit faults
A PTZ that becomes stiff or stops turning shortly after installation is common. Causes other than product defects include:
- Installing a camera intended for upright mounting in an inverted or suspended orientation, increasing drive load and damaging the motor.
- The camera and housing weight exceeding the PTZ's rated load, especially with heavy outdoor domes, causing inability to move—particularly in the vertical axis.
- Outdoor PTZ failure due to extreme temperatures or inadequate waterproofing/frost protection.
7. Faults caused by characteristic impedance mismatch of the transmission line
Interference may appear as equally spaced vertical bars whose frequency is an integer multiple of the line frequency. This happens when the video cable characteristic impedance is not 75 ohms, causing impedance mismatch. Remedies include series resistors at the source or termination resistors at the load. For short transmission distances (typically under 150 m), poor cable may not yet show symptoms, but select quality video cable and perform sampling tests when necessary.
Image Distortion and Night Vision Issues
8. Image warping or geometric distortion
This may be caused by faulty geometric correction circuits in the camera or monitor, optical lens issues, poor internal contacts in PTZ cameras, or impedance mismatch between the camera output and the equipment.
Black vertical or horizontal bars mixed into the image
Usually caused by excessive ripple on the camera power supply output. Improve filtering and use a high-quality regulated DC power supply.
9. Infrared night-vision cameras show normal image in daytime but whiteout at night
This typically occurs when infrared reflection is present in the environment or the camera is used in a small confined space, causing strong IR reflection. First check for reflective objects and improve the environment if possible. Also verify the camera's effective IR range; using a long-range IR camera in a small space can cause overexposure at night.
10. Common types of video interference
- Black or white rolling bars are often 50 Hz mains interference caused by ground potential differences between front-end devices and the control center, or by degraded power supply performance.
- Snow or speckle noise is mainly due to signal attenuation on the transmission line and coupling of high-frequency interference.
- Ghosting, washed-out images, character jitter, or equally spaced vertical bars are usually caused by impedance mismatch when the video cable or equipment is not 75 ohms.
- Diagonal, jumping, or power-related interference can stem from poor cable quality (especially poor shielding), power supply ripple, or a strong nearby interference source.
- Large-area mesh noise, also called single-frequency interference, mainly results from shorts or opens between the cable core and shield or poor BNC contact.
Installation and Debugging Tips
Below are several practical issues encountered during installation and debugging and how to approach them.
1. Stuttering video (frames drop or jump when people walk)
Common causes in IP camera systems:
- Switch configuration or bandwidth limitations. For up to six cameras, a 100 Mbps switch can be acceptable; above that, use a switch with Gigabit uplink. Choose reputable switch brands rather than low-cost unknown brands. Reducing the number of connected cameras can also help.
- Poor camera quality. Small, low-cost assemblers may sell cameras without proper aging tests, leading to large latency and stuttering when multiple cameras are connected.
- Network cable issues. Nonstandard or non-oxygen-free copper cables can age and develop packet loss over time, especially on long runs, causing stuttering.
- Decoder or NVR processing capacity is insufficient. If the decoder is overloaded, video will stutter; replacing the device may be required.
2. No network video display
Common causes:
- Network disconnected. Check the camera's switch port LEDs. If the LED is on and blinking, the network link is OK; otherwise try a different port and inspect both cable ends.
- Power supply failure. Measure the camera supply with a multimeter. Typical voltages are 12 V for fixed cameras and 24 V for some dome cameras. Replace the adapter if voltage is abnormal.
- Camera failure. Cameras can fail and often require factory repair.
3. Multiple camera streams suddenly go offline
Possible causes include:
- Fiber cable cut. This is a common fault in the field when digging damages fiber.
- Fiber transceiver failure. Check the transceiver status LEDs to identify faults.
- The core switch failure. For example, a PoE switch may have grouped power modules; if one group fails, a set of ports lose power.
Troubleshooting methods are varied; the key is systematic fault isolation. Experience helps quickly identify likely causes. When in doubt, swap components such as transceivers to confirm the fault source.
