COFDM Video Transmitter Parameters Explained

Complete Explanation of COFDM Video Transmitter Parameters

Understanding FREQ, बीडब्ल्यू, FEC, सैनिक, मानचित्र, ATTEN, UART, EVNE, and Channel Lock

When customers receive a COFDM video transmitter, they often notice a set of technical parameters displayed on the screen or OSD (ऑन-स्क्रीन डिस्प्ले). A typical example might look like this:

For many users, especially those who are not radio engineers, these values look confusing. तथापि, each of them plays a crucial role in how the COFDM transmitter sends stable, low-latency video over long distances.
This article explains all these parameters in detail, what they stand for, and how to adjust them correctly for your application — whether you are using COFDM transmitters for drones, वाहनों, or tactical video systems.

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FREQ — Frequency

Full Name: परिचालन आवृत्ति
उदाहरण: FREQ: 830MHz

This shows the RF center frequency used by the transmitter. It defines where in the radio spectrum the video signal is transmitted.

यह काम किस प्रकार करता है:
The transmitter modulates the digital video signal into an RF carrier. The receiver must tune to the exact same frequency to demodulate and decode the video.

Typical frequency ranges:

• 300–900 MHz for long-range, better penetration through obstacles.
• 1.2 गीगा, 2.4 गीगा, या 5.8 GHz for short-distance, higher data rate transmission.

Impact:

• Lower frequency (जैसे, 700–900 MHz): Better penetration and longer range, ideal for drones or mobile units in urban areas.
• Higher frequency (जैसे, 5.8 गीगा): Higher throughput, but shorter range and more easily blocked by buildings.

Practical Tip:
Always make sure the transmitter and receiver use exactly the same frequency. Even a 1 MHz difference will cause the receiver to lose lock.

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BW — Bandwidth

Full Name: चैनल बैंडविड्थ
उदाहरण: BW: 2MHz

Bandwidth defines how wide the transmitted signal is on the frequency spectrum. It determines how much data (वीडियो + नियंत्रण) can be transmitted at once.

Common values: 1 मेगाहर्ट्ज, 2 मेगाहर्ट्ज, 4 मेगाहर्ट्ज, 8 मेगाहर्ट्ज.

Explanation:

• ए wider bandwidth allows more data throughput, enabling higher-resolution or higher-frame-rate video.
• ए narrower bandwidth uses less spectrum and provides longer range and stronger penetration, but at the cost of data speed.

Example comparison:

बैंडविड्थ	आधार - सामग्री दर	श्रेणी	Suitable For
1 मेगाहर्ट्ज	कम	सबसे लंबे समय तक	Low bitrate or SD video
2 मेगाहर्ट्ज	Medium	Long	HD video over long distance
4 मेगाहर्ट्ज	उच्च	Medium	High-quality HD or low-latency video
8 मेगाहर्ट्ज	Very High	Short	Close-range or line-of-sight applications

Practical Tip:
For drone or tactical applications, 2 मेगाहर्ट्ज is often the best balance between range and quality.

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FEC — Forward Error Correction

Full Name: अग्रेषित त्रुटि सुधार
उदाहरण: FEC: 2/3

FEC adds redundant information to the transmitted signal so that the receiver can detect and correct errors caused by noise, दखल अंदाजी, or weak signal conditions.

Typical ratios: 1/2, 2/3, 3/4, 5/6.

Interpretation:

• 1/2 → Strong error protection (half of the data is error correction).
• 5/6 → Weaker error protection but higher throughput.

Effect on performance:

• Lower FEC ratio = more reliable link, less data rate.
• Higher FEC ratio = faster data rate, needs strong signal.

उदाहरण:
For long-distance drone transmission, FEC = 1/2 या 2/3 is ideal.
For short-range, high-quality streaming, you can use 3/4 या 5/6.

Practical Tip:
If your video occasionally freezes or breaks under weak signal, try lowering FEC to 1/2.

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GI — Guard Interval

Full Name: रक्षक मध्यांतर
उदाहरण: GI: 1/32

A guard interval is a short pause inserted between COFDM symbols to prevent inter-symbol interference caused by reflections or multipath signals.

Why it matters:
In real-world environments, radio signals bounce off walls, वाहनों, or the ground, creating multiple delayed copies of the same signal. Without a guard interval, these reflections would overlap and corrupt the next symbol.

Typical values: 1/4, 1/8, 1/16, 1/32.

Effect:

• Longer GI (जैसे, 1/4): Better resistance to echoes, ideal for urban or complex terrain, but slightly reduces data rate.
• Shorter GI (जैसे, 1/32): Higher speed, suitable for open field or direct line-of-sight links.

उदाहरण:
If you’re transmitting through buildings or around corners, set GI to 1/8 या 1/16.
If it’s a clear open field, 1/32 works fine.

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MAP — Mapping (Modulation Type)

Full Name: Constellation Mapping या Modulation Type
उदाहरण: MAP: QPSK

MAP defines how binary data (0s and 1s) are mapped onto the carrier wave — essentially, which modulation scheme is used.

Common modulation types:

• QPSK (Quadrature Phase Shift Keying): Transmits 2 bits per symbol; very stable, suitable for weak signals and long range.
• 16QAM: Transmits 4 bits per symbol; higher throughput, but needs strong signal.
• 64QAM: Transmits 6 bits per symbol; maximum data rate but most sensitive to noise.

Effect:

मॉड्यूलेशन	Bits/Symbol	आधार - सामग्री दर	Signal Tolerance
QPSK	2	कम	उत्कृष्ट
16QAM	4	Medium	मध्यम
64QAM	6	उच्च	कम

Practical Tip:
For long-range, गतिमान, or drone systems, QPSK is the best option.
If your system is fixed and the signal is strong, 16QAM can improve throughput.

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ATTEN — Attenuation

Full Name: Transmit Power Attenuation
उदाहरण: ATTEN: 0dB

This parameter adjusts the output RF power of the transmitter.
Attenuation simply means how much the signal is reduced before transmission.

यह काम किस प्रकार करता है:

• 0 डीबी = full output power (no reduction).
• Higher dB value = signal power reduced by that amount.

Effect:

• Lower attenuation (जैसे, 0 डीबी): maximum power, longest range.
• Higher attenuation (जैसे, 10 डीबी): reduced power, useful for short-range testing or avoiding interference.

उदाहरण:
When testing indoors, set ATTEN to 10–20 dB to prevent saturating the receiver.
For actual flight or field use, उपयोग 0 डीबी to maximize range.

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UART — Universal Asynchronous Receiver/Transmitter

उदाहरण: UART: 19200

UART refers to the serial communication interface used to configure or control the COFDM module through a data cable or host controller.

19200 represents the बॉड दर — the communication speed between the transmitter and the controlling device.

Common baud rates: 9600, 19200, 38400, 115200.

Purpose:

• Parameter configuration (आवृत्ति, शक्ति, बैंडविड्थ, आदि।)
• Firmware upgrades
• Status feedback (सिग्नल क्षमता, temperature, आदि।)

Practical Tip:
When connecting to a PC or microcontroller, ensure both ends use the same baud rate and parity settings (see “EVNE” below).

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EVNE — Even Parity

उदाहरण: EVNE या EVEN

This refers to the parity bit used in UART communication. It’s a simple form of error detection that ensures data integrity.

विकल्प:

• EVEN (EVNE): Even parity
• ODD: Odd parity
• NONE: No parity bit

समारोह:
Parity bits help detect transmission errors during serial communication.
If the parity doesn’t match between the transmitter and the connected device, data may appear as random symbols.

Practical Tip:
Set the same parity (EVEN/ODD/NONE) on both devices to ensure stable communication.

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Channel Lock

Display Example: “Channel Lock” or “Lock OK”

This message indicates that the receiver has successfully locked onto the transmitter’s COFDM signal — meaning all parameters (आवृत्ति, बैंडविड्थ, FEC, सैनिक, and modulation) match correctly.

If it shows “Unlocked” or “No Lock”:

• Check that both devices have the same आवृत्ति, बैंडविड्थ, FEC, सैनिक, तथा मॉडुलन.
• Verify antennas are properly connected.
• Ensure signal strength is above the threshold.

Once “Channel Lock” appears, the receiver can decode the video and output stable image.

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Summary Table

पैरामीटर	Full Name	उदाहरण	समारोह	Key Effect
फ्रीक	आवृत्ति	830 मेगाहर्ट्ज	Sets RF operating frequency	Must match TX/RX
बीडब्ल्यू	बैंडविड्थ	2 मेगाहर्ट्ज	Defines channel width	Affects data rate & range
FEC	अग्रेषित त्रुटि सुधार	2/3	Adds redundancy for reliability	Balances speed & स्थिरता
सैनिक	रक्षक मध्यांतर	1/32	Reduces multipath interference	Shorter GI = higher speed
मानचित्र	Modulation Mapping	QPSK	Sets modulation scheme	Impacts throughput & signal robustness
ATTEN	Attenuation	0 डीबी	Adjusts transmit power	Higher ATTEN = lower power
UART	Serial Interface	19200	Communication port	Used for control & स्थापित करना
EVNE	Even Parity	EVEN	UART parity setting	Prevents serial errors
Channel Lock	—	Locked/Unlocked	RF synchronization status	Must lock before video output

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अक्सर पूछे जाने वाले प्रश्नों (सामान्य प्रश्न)

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निष्कर्ष

Understanding these COFDM parameters is essential for getting the best performance from your wireless video system.
Each setting—FREQ, बीडब्ल्यू, FEC, सैनिक, मानचित्र, ATTEN, UART, EVNE—affects how your transmitter balances between range, स्थिरता, and video quality.

For most long-range drone and tactical video applications, the following configuration is recommended:

• फ्रीक: within 700–900 MHz
• बीडब्ल्यू: 2 मेगाहर्ट्ज
• FEC: 2/3
• सैनिक: 1/16
• मानचित्र: QPSK
• ATTEN: 0 डीबी

With correct configuration and antenna alignment, COFDM technology can provide robust, कम अव्यक्ता, non-line-of-sight video transmission in challenging environments.