Three Common Issues in Surveillance Projects and How to Fix Them

In this article, let's take a look at the main reasons why network camera footage may experience lag, not display, or intermittently appear.

Network camera manufacturers may have inherent technical flaws, causing the cameras to experience significant delays after prolonged operation, far surpassing the delay time stipulated by national standards. This makes the footage appear jerky. Only by cutting power to the camera can it return to normal. It is recommended to choose well-known brands with reliable after-sales service for surveillance equipment.

 

For customers using network high-definition digital video recorders (DVRs) for display and storage, the decoding capability of the DVR also affects the smoothness of the video. If the number of connected screens exceeds the maximum decoding capability of the decoder, or if the core chip of the DVR is not powerful enough, it can lead to screen lag.

 

In many surveillance projects, NVRs are often fully loaded or connected with cameras of excessively high resolution, exceeding the NVR's capabilities. This can cause insufficient NVR resources, leading to screen lag or non-display. Reducing the bit rate or the number of connected devices can help resolve this issue.

 

Using low-quality network cables that are not made of oxygen-free copper. Standard national network cables should not exceed 100 meters in recommended transmission distance. Poor-quality cables significantly degrade transmission performance. If inferior cables are used, the initial footage may be normal, but as the lines oxidize and decay, signal transmission loss, intermittent connection, and screen lag may occur. It is advisable to choose high-quality national standard network cables during construction and test the resistance over 100 meters to assess cable quality.

 

If a non-wire-speed switch is chosen, it can cause screen lag. When selecting ethernet switches, one should not only consider packet forwarding rate and backplane bandwidth, especially for core switches. Many domestic manufacturers exaggerate these two data points, failing to reflect the switch's true performance. Therefore, it is crucial to choose well-known brands and thoroughly understand the switch's purpose and parameters.

It is recommended to use a 100Mbps switch for less than 8 points and a switch with a 1000Mbps upload port for more than 8 points. For over 50 points, a three-layer aggregation network structure is needed, with the core switch being a reputable brand. Many people choose cheaper brands to save money, leading to difficulties in identifying the cause of faults in the future.

For screen lag, reducing the bit rate or frame rate can usually resolve the issue, but this sacrifices image clarity. If high image clarity is required, it is not recommended to use this method. Instead, identify the root cause of the problem to resolve it.

Regarding lag, the weak current industry network adds a common issue:

Monitoring Preview is Smooth, but Playback is Laggy?
This is usually due to low hard drive read speed or insufficient hardware configuration related to read/write performance in the DVR. You can back up the surveillance footage to a USB drive and view it on a regular computer. It is also recommended to use surveillance-specific hard drives and check the parameters when purchasing.

 

 

During surveillance projects, a common issue is that some camera images do not display. Let's summarize the possible causes and solutions.

 

After setting up the surveillance system and powering it on, some camera images do not display. Many people first suspect the bit rate and try lowering it, but the problem persists.

It could be a network cable issue. The cables are within 100 meters and are Category 5e, tested with a cable tester, and found to be fine. Power issues? Extensive testing on the power supply yields no results.

It turns out that the non-displaying cameras are all about 80-90 meters from the host. Although this distance should be fine, the problem is concentrated here. Testing the resistance of the cables reveals it to be over 30 ohms. The cables are copper-clad aluminum, not oxygen-free copper, purchased from non-standard channels. Standard oxygen-free copper cables should have a resistance of no more than 10 ohms per 100 meters. Replacing them with national standard cables resolves the issue.

 

In a maintenance project, suddenly, images from over a dozen cameras do not display. This usually indicates a power supply issue.

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Upon checking, these cameras are all powered by the same source. Testing from the weak current box to the power supply reveals a faulty leakage circuit breaker.

Replacing it restores the images.

Therefore, leakage circuit breakers need regular inspection during surveillance maintenance.

 

After completing a surveillance project, one camera does not display, while others are fine.

This is often overlooked. Detailed checks of power supply, camera replacement, and network cables yield no results.

The issue lies in the details. During RJ45 Plugs construction, excessive force when stripping the twisted pair can nearly cut the cable, or the connectors may not be wired according to standard sequences. Although they may test as functional, they can cause severe packet loss in gigabit networks. Re-making the connectors according to standard methods resolves the issue.

A friend asks about a newly installed 200-camera surveillance system where many cameras intermittently do not display.

Initial thoughts are bandwidth or IP address configuration issues. After lowering the bit rate and checking IPs, the problem remains.

 

 

So, what do we do now?

We decided to batch ping the monitored IP addresses.

Use the following batch ping command: for /L %D in (1,1,255) do ping 10.168.1.%D

When you input the batch command, it automatically pings all IP addresses within the subnet until it completes. The (1,1,255) in the code specifies the range from 1 to 255, meaning it checks all IPs from 10.168.1.1 to 10.168.1.255, incrementing by 1 each time, until all 255 IPs are checked.

After running the command, we found that some IPs were unreachable, so we needed to check the switch.

First, we asked about the brand of the switch. It was a commonly used home brand, which is not suitable for a 200-camera surveillance project. For such projects, switches from brands like Huawei, H3C, and Ruijie are more appropriate.

In addition to backplane bandwidth and packet forwarding rate, core switches should also be evaluated based on their scalability, virtualization capabilities, link aggregation, redundancy, and stacking features, as these parameters affect the stability of the network system.

 

 

 

Is the power supply voltage stable?

Are the RJ45 connectors loose?

Is there a break or poor contact in the power line?

Has network bandwidth reached its limit, causing intermittent image transmission?

 

This is due to insufficient power or PoE switch wattage. Infrared cameras operate like regular cameras during the day but require more current at night when the infrared lights are on, exceeding the load.

For example, if you have seven 18W cameras and use an 8-port PoE switch with a 150W power supply, the total PoE power is about 140W, which is fine during the day. However, at night, the increased power demand may exceed the switch's capacity, requiring a higher-powered PoE switch, such as one above 200W.