Key Points of Design for LCD Splicing Screen of Public Security Command Center_Splicing Screen_Product News_News Center

From the police task to deduce the display requirements, using a calculable method to determine the number of rows and columns, the number of decoding paths and the level of patchwork, and then the multi-level cascade, agent collaboration, fault recovery and acceptance disputes are locked into the program and contract one by one.

The most expensive mistake in the splicing screen scheme of the public security command center is often not "expensive" but "wrong".Thousands of channels are connected to monitoring, but the number of decoder channels is purchased according to the total number of cameras, and less than one tenth of them can actually be installed on the wall at the same time. The screen wall is sized according to "the bigger the better". The seat looks up at the first row and the farthest row cannot see the text clearly. The seam was 0.88mm, but the construction team had no experience in ultra-narrow edge installation, and the seam was uneven, which was ugier than 3.5mm.The core difference between the public security command center and the ordinary monitoring center lies not in "more signals", but in "multi-level cascaded scheduling logic, deep coupling between agents and business systems, and hard constraints on 7 × 24 fault recovery", which will in turn change every calculation of screen wall, decoding, architecture and acceptance.This article does not list the parameters, but puts each link's"How to calculate, how to judge, how to check and accept"Write clearly: the backstepping formula of the number of rows and columns on the screen wall, the estimation logic of the number of decoding paths, the choice boundary between centralized and distributed, the two-way scheduling design of multi-stage cascade, the operation process of the agent KVM, and the method of turning "7 × 24" and "fault recovery" into testable terms.

1. the number of rows and columns on the screen wall: from the room size and the seat line of sight, it is not "the bigger the better"

The screen wall scale is the first hard figure of the scheme design. It is not determined by "budget" or "momentum", butRoom available walls, seating arrangement and nearest/farthest viewing distanceof common constraints.

Backstepping of the number of rows and columns: measure the wall first, then count the columns and rows.

The LCD splicing screen can only be made by splicing single screens of the same size. The calculation logic of the number of rows and columns is:

Number of horizontal columns A = available width of wall ÷ width of single screen (rounded down)
Longitudinal number of rows B = available height of wall ÷ height of single screen (rounded down) The available size of the wall surface shall be deducted: maintenance/wrapping space on both sides, bottom cabinet or maintenance height, and top reservation.

Take a 55-inch single screen as an example, the appearance size is about 1222mm wide and 696mm high. Assuming that the available wall surface of the command hall has a net width of 6.5 meters and a net height of 3.2 meters, a cabinet/maintenance space of 50cm is reserved at the bottom, 30cm is reserved at both sides, and 20cm is reserved at the top:

Available width ≈ 6500 − 600 (300mm on both sides) ≈ 5900mm. 5900 ÷ 1222 ≈ 4.8, take4 columns。
Available height ≈ 3200 − 500 (bottom) − 200 (top) ≈ 2500mm. 2500 ÷ 696 ≈ 3.6, take3 lines。

The candidate size is obtained4 × 3(12 pieces 55 inches). However, the number of rows cannot be determined by the wall surface alone, but also checked by the sight of the seat. If 4 columns cause the width of the whole wall to exceed the effective range of the agent's field of view, or 3 rows cause the top row to need to look up obviously, it is necessary to reduce the number of rows or adjust the size of a single screen.

Seat sight check: bottom edge height and elevation angle

Operators in the command center usually sit and watch for a long time. The height of the bottom of the screen wall from the ground and the elevation angle of the first row of seats directly determine the fatigue degree. An operational judgment caliber is:The height of the bottom edge of the screen wall from the ground is recommended to be not less than 0.8-1.0 meters (to avoid being blocked by the seat desktop or front row personnel), and the distance from the first row of seats to the screen wall should ensure that the elevation angle does not exceed 15-20. If the depth of the room is insufficient, causing the recent seats to be too close to the screen, even if the number of rows and columns can be calculated, the actual viewing experience will not hold.

At the same time, the distance of the farthest row of seats determines the "lower limit of information readability" of the screen wall ". If the maximum distance exceeds 4-5 times the height of a single screen, the small print and details on the single screen may be illegible and need to be compensated by increasing the size of the single screen, reducing the number of lines, or adjusting the font size of the content. The text and map labels of the public security command center are often dense, and this check cannot be omitted.

Row count is not an isolated number

For the same wall surface, it is 12 pieces for 55 inches to make 4 × 3 and 6 pieces for 65 inches to make 3 × 2. The reduction in the number of screens will reduce the total number of stitches and the complexity of the signal system, but the weight and installation requirements of a single screen will increase. The final determination of the number of rows and columns is the result of the balance of "wall capacity, seat line of sight, single screen size and budget", rather than simply pursuing "more blocks" or "large single screen".

2. the number of screens and decoding at the same time: distinguish between "total access" and "visible capacity"

The number of monitoring channels connected to the public security command center may reach thousands, but the number of channels that can be "clearly displayed" on the large screen at the same time is limited. The most common mistake in the scheme design is to use the "total number of cameras" to directly correspond to the "number of decoder paths", resulting in either serious over-matching or insufficient actual available paths.

First estimate the "monitor capacity that needs to be on screen at the same time"

The prevailing industry estimation logic is:The ratio of key parts monitor to camera shall not be less than 1:3, and non-key parts shall not be less than 1:8. The meaning of this ratio is that not every camera needs an independent "monitor position" to display frequently, but the display resources are allocated according to the degree of importance.

For example, the command center of a sub-bureau is connected to monitoring 800 roads, of which the key parts (bayonet, key unit and key road section) are about 240 roads and the non-key parts are about 560 roads. Proportional estimation:

Monitor capacity required for key parts ≈ 240 ÷ 3 = 80 way.。
Monitor capacity required for non-key parts ≈ 560 ÷ 8 = Bus Route 70。
Total Simultaneously Visible capacity approx.150 Road。

These 150 channels are not "150 screens", but "150 single-channel display positions". If a single screen is divided into 4 screens, the display capacity of 150 channels ÷ 4 ≈ 38 screens; If 9 screens are divided, about 17 screens are used. In the actual scheme, the key parts are usually divided with fewer pictures (to ensure clarity), and the non-key parts are divided with more (to ensure coverage), which requires partition calculation.

Derivation of the number of decoder paths

The nominal "number of ways" of the decoder usually refers to the full decoding capacity, but what is actually needed is.Concurrent decoding capability under target resolution and target segmentation. The derivation logic is:

Number of decoder required paths ≈ number of single-screen splits × number of screens (weighted by partitions)
At the same time, it is necessary to confirm whether the decoding format (H.265/H.264), the maximum resolution of a single channel and the number of output interfaces can correspond to the number of screens.

Take a total of 12 55-inch screens of 4 × 3 as an example. Assuming that the key area is divided into 4 parts by 2 screens (each with 4 channels 1080P) and the remaining 10 screens are divided into 9 parts (each with 9 channels 1080P), the decoding requirement is about 2 × 4 10 × 9 = Bus Route 98. If the decoder is fully equipped with 64 channels 1080P, at least 2 are required (and confirm that the number of output interfaces covers 12 screens).You cannot buy a decoder according to "800 cameras" or "12 screens"-it must be calculated according to "number of concurrent decoding channels under target segmentation.

At the same time, it is necessary to check whether the decoder supports the coding format (H.265/H.264) and networking protocol (GB/T 28181-2022, ONVIF) of the project platform; Under the full number of routes, whether the output picture still maintains the target frame rate and definition, instead of the performance during no-load demonstration.

"Accessing thousands of roads" is not the same as "seeing thousands of roads at the same time"

The expression "support access to XXXX road monitoring" is common in the bidding documents and scheme documents. This "access" refers to the total amount of resources that the platform can manage, not the number of ways displayed on the large screen at the same time. During the scheme verification, the supplier shall be required to clearly write out: under the target single-screen partition number, what is the number of ways that can be decoded on the wall at the same time; Whether the resolution and frame rate of the single-channel picture are degraded when fully equipped; Whether the number of decoder output interfaces matches the number of screens. Without these three numbers, "access capability" has no practical significance for the command center.

3. patchwork: "Suggested Value" and "Exclusion Condition" of Public Security Scene"

The sensitivity of the public security command center to patchwork is higher than that of the ordinary monitoring room, because tracking the target trajectory across the screen and displaying the GIS map across the screen are high-frequency operations. The "visual fracture zone" at the seam will cause the target to jump or "disappear" briefly when crossing the screen. The operator needs additional cognitive load to complete the information, which is unacceptable in emergency response.

Suggested caliber of public security scene

In industry practice and public information, the public security command center usually recommends priority assessment.0.88mm and belowPatchwork. At this level, the patchwork width is close to or less than the human eye's perception threshold for lines at normal command viewing distance. According to the actual case feedback, the 0.88mm patchwork "basically does not feel the picture interruption" when tracking the suspect's track across the screen ".

However, "recommended 0.88mm" does not mean "all public security projects are unconditionally 0.88mm". The conditions for patchwork still depend on recent viewing distance and content type:

Establishment and exclusion conditions of patchwork type selection for public security command center
Condition	0.88mm	1.8mm	3.5mm
Distance to nearest operator seat ≤ 2 m, high-frequency cross-screen map/track tracking	Established, visual continuity priority	Visible but not dazzling, available when budget is limited	Not recommended, patchwork obviously cuts off the content at close range
The nearest operating seat is 2-3 meters away, with monitoring wheel patrol as the main and map as the auxiliary.	Established, but premium returns narrow	Balanced selection	Field prototype verification required, cross-screen tracking may be detectable
Closest distance> 3 m, mainly video rounds and situation overview	High risk of overprovisioning	can be established	Can be established, patchwork is weakened at a long distance.
The construction team has no experience in ultra-narrow side installation.	Exclude or require similar cases	Leveling process to be confirmed	Low construction threshold

Construction capacity is an easily overlooked exclusion condition. The requirements of 0.88mm flat-splice on bracket accuracy, leveling process and construction experience are significantly higher than 3.5mm. If the installation team does not have an actual case of the ultra-narrow edge project, the opposite effect of "the seam is very narrow but the seam is uneven" may occur-the single seam is narrow, but the seam width between the screen is inconsistent, which is visually ugier than the uniform 3.5mm. When 0.88mm is selected, the supplier shall be required to provide installation cases of similar patchwork specifications, and the acceptance criteria for patchwork uniformity shall be agreed in the contract.

4. multi-level cascade: the unique "two-way dispatch" of public security, not one-way "look at subordinates"

The public security command center is usually in the multi-level structure of the province-city-district-county-police station. Many schemes simply understand the "multi-level cascade" as "the superior can adjust the monitoring screen of the subordinate", but the cascade in the public security actual combat isBidirectional: The superior can issue picture scheduling instructions to the subordinate and push key pictures. The subordinate can also upload key pictures to the superior to realize cross-level and cross-regional sharing and collaborative disposal of alarm information.

Three Things to Check for Cascade Design

First, the cascading method. Common approaches include fiber optic cascading and IP network cascading. Fiber cascading has more advantages in real-time and lossless image quality, and is suitable for scenarios with high requirements for cross-screen synchronization. IP cascading has higher flexibility and is suitable for cross-region and multi-node networking. The scheme shall specify the cascading mode and the interface protocol between platforms at all levels (generally, it is required to support GB/T 28181-2022).

Second, two-way scheduling capability. It is not only "the superior looks at the subordinate", but also to confirm whether the superior can push the local picture to the lower-level large screen; Whether the subordinate can actively "push up" the specified picture to the upper-level large screen; Whether the picture resolution and frame rate are maintained during cross-level push; Whether voice/text command synchronization is supported during push. These capabilities directly determine the command efficiency during emergency coordination.

Third, the impact of cascading on the local display system. When the superior calls or pushes the signal, will the layout and plan of the local large screen be disturbed? Will the cascade signal be superimposed as an "independent window" or can it replace the local screen? This requires confirming the operation flow with the owner in the plan stage and writing acceptance test items.

Cascade is not "just pass the interface"

The acceptance of multi-level cascade cannot only test "whether you can see the picture of superior/subordinate". It should be tested: the response time of push/pull; Whether the window opening and scaling of cross-level pictures on the local large screen are smooth; Synchronization of cascade signal and local signal on the screen at the same time; When the network is restored after interruption, whether the cascade session can be automatically rebuilt. These are the nodes that really affect the use in actual combat.

5. agent collaboration and KVM: the large screen is the "presentation side", and the operation process determines the signal architecture.

The daily operation of the public security command center is not "one person standing in front of the large screen to switch signals", but multiple agent operators control the business computer through KVM system, push the screen to the large screen, grab the content of the large screen to the local, or cooperate with each other among the agents to read. The operation process of agent collaboration directly determines the signal processing architecture and KVM configuration.

Typical agent operation process and corresponding technical requirements

Capability Requirements for Seat Operation Actions and Signals/KVM
Operation action	Typical Implementation	Requirements for architecture/KVM
The agent pushes the local business computer screen to the designated area of the large screen.	KVM Shortcuts/OSD Menu/Mouse Drag and Drop	Support signal push on screen and large screen partition management; Push delay can be perceived but does not affect operation
The seat grabs the signal on the large screen to the local display	KVM capture function	Support large screen signal capture; after capture, the local can continue to operate the signal
Access/takeover of each other's business computers between agents	KVM Permission Management and Remote Takeover	Permission classification; Operation log mark; Acceptable takeover delay
Call the plan with one key and screen multiple signals according to the preset layout.	Plan management and one-click switching	The number of plans meets the business scenario (e. g. daily duty, emergency response, major security);
Leader/Commander adjusts large screen layout by tablet or touch	Visual central control/mobile end control	Authority differentiation; operation traceability; linkage with agent KVM system

In the scheme design,The "large screen display system" and the "seat KVM system" cannot be regarded as two unrelated packages. If KVM's push-up function is not properly connected with the window opening/layout capability of the large-screen processor, the seat operator may only be able to "push all the signals up" and cannot realize "push all the signals to the designated window of the large screen and automatically adjust the layout". For this kind of cross-system linkage capability, the responsibility boundary should be defined in the scheme stage (unified joint debugging by integrators, or interfaces provided by KVM manufacturers and large-screen manufacturers respectively), and end-to-end operation testing should be done in the acceptance.

6. Centralized vs. Distributed: Choose by scale, scale, and O & M capabilities, with no default "advanced"

The choice between centralized and distributed architecture is the easiest link in the design of the public security command center. Distributed has obvious advantages in cross-regional, multi-level, and large-scale scenarios, but its network dependencies, node costs, and integration complexity are also real. Centralized in small and medium-sized projects with concentrated signals, the stability and image quality are better without loss, but the expansion is affected by slot restrictions and single point of failure.

The choice boundary between centralized and distributed (public security command center scenario)
Judgment dimension	tend to be centralized	tend to be distributed
Number of screens and signal scale	The number of screens is small (e. g., ≤ 16), and the signal sources are concentrated in the same machine room or adjacent areas.	The number of screens is large, the signal source is cross-floor/cross-building/cross-regional, and the expansion demand is predictable.
Multi-level Cascading Requirements	Fewer cascade levels and low interaction frequency	Province-city-district multi-level two-way scheduling is frequent, requiring node-based access and flexible expansion.
Agent Collaboration Complexity	The number of seats is small, and the logic of pushing the screen is simple.	High number of seats, high requirements for cross-agent collaboration and permission management
Operation and maintenance capability	The operation and maintenance team is familiar with traditional centralized equipment, and the fault location is intuitive.	With network operation and maintenance capabilities, able to accept the management and troubleshooting complexity of distributed nodes
Network conditions	No independent, high-quality network environment	Offers a dedicated network that meets bandwidth, latency, and redundancy requirements

A practical order of judgment is:First look at "whether the expansion requirements are real and predictable", then look at "whether the network and operation and maintenance capabilities are supported", and finally look at "whether the budget covers the node and network costs brought about by distribution". If the expansion requirement is only "a few screens may be added in the future", the reserved slot and bandwidth margin of the centralized processor are usually a more economical choice. If the project clearly needs to access multiple subordinate units and cross-regional scheduling, the distributed node expansion and fault isolation value will really be established.

Distributed "hidden costs" to be asked at the scenario stage

If only the input/output nodes are listed in the quotation of the distributed scheme, and the supporting switches, fiber/network cables, cabinet space, network management and security equipment are omitted, the later additions may significantly push up the total cost. During the scheme verification, the supplier shall be required to make clear whether the network matching is included in the quotation; The scope of influence when a single node fails (whether it is only the black screen of the node or the associated signal); The responsible party for node firmware upgrade and spare parts supply. The answer to these questions is more likely to determine the success or failure of the project than "whether it is distributed.

7. 7 × 24 and fault recovery: turning "labels" into testable terms

"Support 7 × 24" is the standard expression of the public security command center scheme, but what really determines the availability of the system isWhen each link fails, "can the picture be maintained, how long to recover, and whether it is consistent after recovery". The single point should be identified in the program link by link, and the recovery index should be written as a testable clause.

Critical link failure impact and testable recovery requirements
Segment	Failure Scenario	Effect on Display	Program requirements (can be written into contract/acceptance)
Control/Management Platform	Control server or management software failure	The large screen may be out of control, but is the displayed screen maintained?	Requires "large screen to keep last picture when control fails"; no need to reconfigure layout after recovery
Processing equipment	Processor Master Card/Power Supply Failure	May cause some or all of the signal to be interrupted	Dual power supply hot standby, main control card hot standby; The switching process is not black, and the switching time is written for acceptance (e.g. ≤ 20ms)
Input signal	A certain signal source is lost	Corresponding window black screen or blue screen	Support input signal hot backup: automatically switch to standby signal when the signal is lost, large screen without black screen/splash screen
Network (Distributed)	Switch or link failure	Associated Node Signal Interruption	Link redundancy (optical network port hot standby); single node/single link failure does not affect other nodes
Power supply	Mains interruption or power module failure	Equipment shutdown, manual restart after recovery	Redundant power supply; the system automatically restarts and restores to the preset state after power failure recovery (or manual recovery process is specified)

Acceptance, these indicators can not only look at the "normal power". should be doneFault injection test: Unplug the main power supply and observe whether the picture is interrupted due to the switching of the standby power supply. Disconnect all the input signals and observe whether the backup signal takes over automatically. Simulate the downtime of the control platform and observe whether the large screen picture is maintained. The switching time and picture holding status shall be recorded in the acceptance report as the reference within the warranty period.

Spare parts and response time are also part of "reliability"

No matter how good the redundant design is, spare parts and response are needed to cover the bottom. The contract shall specify: on-site spare parts list and storage location of key spare parts (power supply module, master control card and fan); Time limit for fault response (such as 2-hour remote response and 24-hour on-site arrival); Temporary disposal plan before the arrival of spare parts. For command centers with 7 × 24 operation for more than 5 years, the spare parts supply cycle (whether the panel/module is continuously supplied during the project life cycle) should also be included in the clause.

8. acceptance dispute handling: first determine the nature, then determine the responsibility, and lock the process with documents.

The acceptance of public security projects often involves many parties (owners, user departments, audit, supervision). If the acceptance criteria only write "clear picture and stable operation", disputes are almost inevitable. The mechanism for handling acceptance disputes can determine the smooth closure of the project more than the acceptance criteria themselves.

Translate acceptance criteria as "conditional method evidence"

Each key indicator should be written in a three-stage executable form. For example, the patchwork index should not only write "≤ 0.88mm", but should write:Test conditions(at the nearest operating seat distance at the project site and under normal ambient light);Testing method(Display pure white/pure black/grid test chart, visual and supplemented by feeler gauge or image measurement);Delivery of evidence(Acceptance record form with photos/measured values, signed by both parties).

The acceptance of display quality can refer to the five-level damage score of subjective evaluation of image quality in GB 50198-2011 "Civil Closed Circuit Surveillance Television System Engineering Technical Specification", which is required to reach more than four levels. Signal access and networking shall meet the relevant requirements of GB/T 28181-2022. Indicators such as switching time and fault recovery shall be based on the measured values agreed in the contract, not the nominal values of the supplier.

Handling process for not passing acceptance

The following shall be agreed in advance in the Contract or Acceptance Plan:(1) Qualitative problem-When the acceptance fails, the problem phenomenon shall be recorded in writing first, and the qualitative basis shall be the category of "product defect, installation accuracy, signal link and function not realized" according to the contract standard, and the qualitative basis shall be the test record and the contract index;(2) Rectification period-- How long the responsible party completes the rectification;(3) Time limit for re-inspection-- How long shall Party A organize the re-inspection after the rectification is completed;(4) Payment Processing-The undisputed part shall be paid in advance, and the disputed part shall be paid after the re-inspection is passed;(5) Late acceptance-- If Party A delays the acceptance without justifiable reasons and does not raise a written objection, the conditions of "deemed to be passed" shall be agreed. Without this mechanism, no matter how detailed the acceptance criteria are, they may fall into an indefinite "rectification-re-inspection" cycle.

9. Quotation Boundary: Five Items Most Easily Missed in Public Security Projects

If the quotation of the public security command center is only higher than the "unit price per screen", the later increase will almost inevitably occur. The following five items are the boundaries of high-frequency omissions in the proposal quotation, which should be confirmed "with/without" item by item at the quotation stage ".

Authorization of signal access and the cost of joint adjustment. When the display system is connected to the video networking platform, GIS system, and service platform, interface authorization, account opening, and coordination of third-party manufacturers may be required on the platform side. Who will bear this part of the workload and costs should be specified in the quotation.
The configuration range of the KVM agent system. The number of seats, the number of KVM nodes, whether inter-seat collaboration and permission management are required, and whether the display and keyboard mouse at the seat end are included-these are easily missed by "large screen quotation.
Network supporting (distributed project). Whether the switch, optical fiber/network cable, optical module, cabinet space and network management software required for distributed architecture are included in the quotation. If the network is provided by the owner, the interface boundary and the responsibility of the joint debugging shall be clarified.
Commissioning and preparation of plan. Commissioning should not only include "signal communication and bright picture", but also include the configuration and optimization of the plan (daily duty, emergency response, major security and other scenarios). The workload and revision rounds of the preparation of the plan shall be agreed in the quotation.
Warranty starting and spare parts supply. The warranty period starts from "acceptance" or "delivery"? Is the list of spare parts included in the quotation? Does the supply life of the spare parts of the panel/module cover the service life of the project? These terms directly affect the long-term cost.

Falling point of quotation verification: All bidders are required to fill in the same sub-template, focusing on checking whether the above five items are clearly listed in the three paragraphs of "equipment and boards, integration and construction, service and delivery. Any subject written as "standard", "according to the actual" and "discussed separately" shall require written clarification at the bid evaluation stage and be attached to the contract.

10. FAQ

What is the number of screen wall rows in the public security command center?

First measure the available width and height of the wall surface (excluding maintenance on both sides, bottom cabinet and top reservation), divide by the width and height of a single screen respectively, and round down to obtain the number of candidate columns and rows. Then check the elevation angle with the nearest seat distance (it is recommended not to exceed 15-20), and check the readability of the information with the farthest seat distance. The number of rows is not determined by budget or "momentum", but by the common constraint of "wall capacity x seat sight.

Access to thousands of road monitoring, decoder to buy how many road?

You cannot buy the total number of cameras. First, according to "key parts 1:3, non-key parts 1:8" to estimate the monitor capacity that needs to be on the screen at the same time, and then according to "single screen division number x screen number" to calculate the number of concurrent decoding paths. For example, 800-way monitoring, key 240-way, non-key 560-way, it is estimated that about 150-way can be seen at the same time; If the weighted average of 12 screens is divided into 6, the decoding requirement is about 72, and then the number of units is determined according to the decoder's single-machine capability and the number of output interfaces. The resolution and frame rate under full decoding and whether the output interface covers the number of screens must be checked together.

Does patchwork have to be 0.88mm?

Due to high-frequency cross-screen tracking and map research and judgment, the public security command center usually recommends giving priority to the evaluation of 0.88mm and below, because the "visual fracture" at the splicing seam has obvious influence in close operation. However, 0.88mm is not unconditionally established: if the nearest operating seat distance is more than 3 meters and video rounds are the main ones, 1.8mm may be enough; If the construction team has no experience in ultra-narrow side installation, the 0.88mm may be discounted due to uneven splicing. The exclusion judgment shall be made in combination with the distance, content and construction capacity, and the prototype verification shall be made under the real distance.

Does multi-level cascade only need to see the superior/subordinate picture?

Not enough. The cascade in public security combat is two-way: the superior can push pictures and scheduling instructions to the subordinate, and the subordinate can actively upload key pictures to the superior. The acceptance shall test the response time of push/pull, the smoothness of window opening and scaling of cross-level pictures on the local large screen, the synchronization of cascade signals and local signals on the screen at the same time, and whether the cascade session can be automatically rebuilt after the network interruption is restored.

Centralized and distributed, how to choose the public security command center?

"Distributed More Advanced" is not preset ". For projects with fewer screens, signal concentration, and unclear expansion requirements, the stability, lossless picture quality, and cost advantages of a centralized processor are more practical. The value of distributed nodal expansion and fault isolation can only be realized for projects with many screens, frequent cross-floor/cross-regional, multi-level two-way scheduling, and high complexity of agent collaboration. The decision is based on "whether the expansion demand is real and predictable" and "whether the network and operation and maintenance capabilities are supported", rather than the old and new technical terms.

How to test the "double hot standby" acceptance?

You can't just look at whether there is a "dual power supply" in the equipment list ". Fault injection test should be carried out: unplug the main power supply and observe whether the standby power supply switching causes the screen interruption and the switching time; Simulate the downtime of the control platform and observe whether the large screen keeps the last screen; Disconnect all the input signals and observe whether the backup signal takes over automatically. The switching time and picture holding status shall be recorded in the acceptance report, and the measured value agreed in the contract shall be taken as the basis for judgment, rather than the nominal value of the supplier.

XI. Conclusion

The complete judgment chain of the design of the splicing screen scheme of the public security command center can be compressed into five steps:

Set the number of rows and columns for the wall surface calibration seats → calculate the number of decoding paths according to the "key/non-key ratio × number of divisions" → set the seam according to the "distance content construction capability" → select the structure according to the "expansion demand network conditions" → write 7 × 24 and fault recovery as acceptance clauses that can be injected into the test.

The particularity of the public security scene is not at the quantitative level of "more signals", but atThe scheduling logic of multi-level two-way cascade, the coupling process of agent KVM and large screen, and the hard constraints of 7 × 24 fault recovery.. These three things will in turn change the screen wall size, decoding configuration and architecture choice. The professionalism of the scheme is not reflected in the length of the parameter table, but inThere is an explainable calculation behind every key number, and there is an executable test method for every reliability promise.. Only when the number of rows and columns and the number of decoding paths are calculated correctly, the stitching and structure are selected correctly, and the acceptance conditions of cascading, seating and fault recovery are locked into the contract, can the scheme stand the test of actual combat.

First calculate, then select the type; First determine the nature, then determine the responsibility; The screen of the command center is designed, not piled up.

Design Points of LCD Splicing Screen Scheme for Public Security Command Center