LED modules cannot draw an image on their own. The receiving card takes the signal sent by the controller and decides how often and how brightly each LED on the module lights up. Even with the same modules, a different receiving card or controller means different refresh rate, grayscale, brightness uniformity and fault handling. That is why we carry receiving cards (DH7508-S / DH7512-G) in our lineup separately from modules.
This article explains what control components do and what to look for in quotes and specifications.
1. What a receiving card does
One per cabinet, driving several modules.
A receiving card is a board that receives the video signal from the controller (sender) and drives the modules attached to its cabinet. Each card has a fixed pixel capacity (e.g. 512×384) and number of module ports (8–16 HUB75), so the number of cards needed is calculated from the screen size and pitch. Refresh rate, grayscale, storage of brightness and color correction (calibration) values, and per-module brightness uniformity are all handled here.
Irregular modules (trapezoidal, triangular) or irregular layouts require a receiving card that supports custom arrangements. The Cheongdo Market arch was one such case, where choosing the receiving card went hand in hand with module design.
2. Controllers — synchronous vs. asynchronous
Asynchronous for permanent operation, synchronous for events and live use.
There are two kinds of controllers: synchronous controllers that send the PC screen in real time (stages, events, live broadcasts), and asynchronous controllers that store content, play it independently and allow remote publishing from the cloud (outdoor promotion, information). When a large screen exceeds the pixel capacity of one controller (e.g. 1.3, 2.6 or 6.5 million pixels), several are combined. Operation is covered in detail in the Content operation article.
3. What to check in specs
Compare these items on receiving card and controller spec sheets.
| Item | Meaning · standard |
|---|---|
| Pixel capacity / ports | Max pixels and module ports (HUB75) one receiving card drives. Screen size ÷ pixel capacity = cards needed |
| Refresh rate | At 3,840Hz or higher, no banding on camera. 1,920Hz is fine for promotional use |
| Grayscale | 12–16 bit. Gradation in dark scenes and gradients |
| Calibration support | Whether per-module and per-pixel brightness and color correction values are stored |
| Irregular layout support | Trapezoidal, triangular and round modules; rotated and free-form mapping |
| Redundancy / loopback | Signal stays up via the adjacent cabinet path even if one cable is cut |
| Monitoring | Remote reporting of temperature, voltage, fan and signal status |
| Compatibility | Pairing of module driver IC and controller maker (same manufacturer family recommended) |
4. Why choose them as a "set"
It is safest to match modules, receiving cards and controllers within one manufacturer family.
Calibration and advanced features (HDR, low-grayscale correction) only work when the module driver IC, receiving card firmware and controller software are compatible. If you buy and combine them separately, the screen may turn on, but uniformity correction may not work or firmware updates may be blocked. That is why we supply modules and receiving cards together.
With replacement and expansion in mind, it is good to keep spare receiving cards equal to 5–10% of the screen's cabinet count. A single faulty receiving card shows up as an entire cabinet going dark, and with a spare on hand it can be replaced on site in 10 minutes.
① Common symptoms and control components
With these symptoms, check the control side before the modules.
| Symptom | Suspected part |
|---|---|
| An entire cabinet goes dark | Receiving card or data cable |
| Part of the image shifts or overlaps | Receiving card mapping settings |
| Banding when filmed | Low refresh rate → receiving card and driver settings |
| Brightness or color differs by module | Calibration values lost → recalibrate receiving card |
| Whole screen black or blue | Controller, input signal or network |
② Purchase checklist
Check that these items are stated in the quote.
Receiving card model, quantity (incl. spares), pixel capacity and ports- Controller type (sync/async), pixel capacity and quantity
- Refresh rate, grayscale and calibration support
- Manufacturer compatibility across module, receiving card and controller
- Redundancy (loopback) and monitoring
- Firmware updates and remote support method
Receiving card role and selection: Guide to NovaStar LED Receiving Card · How to Choose a NovaStar Receiving Card · EagerLED, MRV412-N Receiving Card / Controllers: Linsn, Synchronous vs Asynchronous · Dynamo, Controller Hardware / Spec terms: Ledman, Decode LED Display Specs. Spare parts ratios and symptom handling are based on LO-GIN IT after-sales service records. No domestic competitor materials were cited; figures vary by manufacturer, model and site.
Recommended specs for this guide
- Receiving cards: 1 per cabinet + 5–10% spares
- Controller: async for permanent / sync for events
- Refresh 3,840Hz · grayscale 12-bit or higher
- Module, receiving card, controller from the same family