How to transmit analog video wirelessly Using Radio Frequency (RF) Transmitters

In this tutorial, we will delve into the wireless transmission of analog video, specifically focusing on utilizing Video Receiver (VRX) and Video Transmitter (VTX) modules. This method is commonly employed in the realms of RC Cars and First Person View (FPV) Drones. To transmit video wirelessly, VRX and VTX modules play pivotal roles in establishing a seamless connection. VRX, functioning as the receiver, captures the analog video signals, while the VTX, as the transmitter, broadcasts these signals wirelessly. This technology is widely embraced in the RC hobbyist community, providing real-time video feeds for FPV applications, enhancing the immersive experience of piloting drones or controlling RC vehicles remotely. Understanding the intricacies of these modules is essential for enthusiasts seeking to harness the capabilities of wireless video transmission in their RC and FPV endeavors.

Several methods of wireless video transmission.

Wireless video transmission has become increasingly popular due to the convenience it offers in eliminating the need for physical cables. Several methods are used for wireless video transmission, each with its own strengths and weaknesses. Here are some common methods.

1. Wi-Fi:
   • Application: Wi-Fi is widely used for wireless video transmission in home networks, security cameras, and smart TVs.
   • Pros: Ubiquitous, supports high data rates, suitable for short to medium-range applications.
   • Cons: Susceptible to interference, range limitations.
2. Bluetooth:
   • Application: Bluetooth is commonly used for short-range wireless video transmission in devices like smartphones, tablets, and laptops.
   • Pros: Low power consumption, widely supported in consumer electronics.
   • Cons: Limited range, lower data transfer rates compared to Wi-Fi.
3. Wireless HDMI:
   • Application: Wireless HDMI transmits high-definition video and audio signals between devices, such as from a Blu-ray player to a TV.
   • Pros: High-quality video and audio, easy setup, no need for separate cables.
   • Cons: Limited range, potential for interference.
4. Miracast:
   • Application: Miracast is a standard for wireless display mirroring, allowing users to stream video from one device to another, such as from a smartphone to a TV.
   • Pros: Device-to-device streaming, supports HD video.
   • Cons: Limited range, device compatibility issues.
5. AirPlay:
   • Application: Developed by Apple, AirPlay allows wireless streaming of audio and video between Apple devices and compatible speakers or displays.
   • Pros: Seamless integration with Apple ecosystem, high-quality streaming.
   • Cons: Limited to Apple devices, may have latency in some scenarios.
6. Wireless USB:
   • Application: Wireless USB technology enables the wireless transmission of USB data, including video signals, between devices.
   • Pros: Similar functionality to a wired USB connection, suitable for various peripherals.
   • Cons: Limited range, potential for interference.
7. Radio Frequency (RF) Transmitters:
   • Application: RF transmitters can be used for wireless video transmission in applications like FPV (First Person View) for drones.
   • Pros: Can provide longer ranges, suitable for specific applications like FPV.
   • Cons: May require specialized equipment, potential for interference.
8. 5G Networks:
   • Application: With the advent of 5G technology, it is increasingly used for high-speed wireless video transmission, especially in mobile applications.
   • Pros: High data rates, low latency, supports various multimedia applications.
   • Cons: Limited coverage in some areas, infrastructure deployment challenges.

The choice of wireless video transmission method depends on factors such as the required range, data transfer rates, device compatibility, and the specific application or use case.

You can watch the following video or read the written tutorial below.

Overview

I use VTX (Video Transmitter) and VRX (Video Receiver) modules for this. With this, an analog video can be transmitted to a distance of 600m – 5km. The distance varies according to the trees, buildings, and environmental conditions in the environment. I am using RHCP 5.8G Circular Polarized Mushroom Antenna for VTX module and VRX module. The camera module I use is a Foxeer Razer Mini 1500 TVL FPV camera.

Components Needed

Before we begin, make sure you have gathered all the necessary components. The purchase links are in the description of my YouTube video.

• Analog FPV goggles ( I use EV800 5.8G FPV Goggles )
• Analog VTX ( I use Matek 5.8G VTX-HV Switchable Video Transmitter )
• FPV Camera ( I use Foxeer Razer Mini 1500 TVL FPV camera )
• Two RHCP 5.8G circular polarized mushroom antenna
• MMCX to SMA RF Cable ( This varies depending on the VTX used )
• Two 18650 Rechargeable Battery 3.7V
• 18650 Li-ion Battery Holder 2-Way

What is analog VTX?

VTX typically stands for “Video Transmitter,” which is commonly associated with the drone and FPV (First Person View) communities. Analog VTX refers to a video transmitter that sends analog video signals, as opposed to digital signals.

An analog VTX is a crucial component in FPV systems, particularly in drones and remote-controlled vehicles where real-time video feedback is essential for the operator. Here’s a brief description of the key aspects of an analog VTX:

1. Functionality:
   • The primary function of an analog VTX is to transmit video signals wirelessly from a camera on the drone or vehicle to a receiving device, such as FPV goggles or a monitor.
2. Frequency Bands and Channels:
   • Analog VTX systems operate on specific frequency bands and channels within those bands. Common frequency bands include the 5.8 GHz and 2.4 GHz bands. Pilots often need to select a channel that is not in use to avoid interference.
3. Power Output:
   • Analog VTX systems come in various power output options, typically ranging from 25mW to 800mW or more. Higher power allows for longer-range transmission, but regulations and guidelines may restrict the maximum power output in certain regions.
4. Adjustable Output Power:
   • Many analog VTX modules offer adjustable power settings to comply with local regulations or adapt to the specific needs of the flight environment.
5. Channels and Bands Switching:
   • VTX modules often feature a button or digital interface that allows users to switch between different channels and bands. Some advanced VTX models may even support SmartAudio or Tramp protocols, enabling remote channel adjustments through the flight controller.
6. Antenna Connector:
   • Analog VTX modules typically come with an SMA or RP-SMA connector for attaching an antenna. The choice of antenna can significantly affect the signal range and quality.
7. Input Voltage and Current:
   • Analog VTX modules have specific input voltage requirements, and understanding these is crucial to ensure compatibility with the overall power distribution system in the drone.

What types of antennas are used for analog VTX and VRX goggles?

For analog video transmitters (VTX) and video receivers (VRX), several types of antennas are commonly used in the FPV (First Person View) and drone racing communities. The choice of antenna can significantly impact signal range, coverage, and overall video quality. Here are some commonly used antenna types:

1. Linear Polarized Antennas:
   • Dipole Antennas: Dipole antennas are simple and straightforward. They consist of a straight wire or pair of wires, and they emit a linearly polarized signal. They are easy to manufacture and provide good performance for short to medium-range applications.
   • Pagoda Antennas: Pagoda antennas are a type of circularly polarized (CP) antenna, but they are often used with linear polarized antennas in a diversity setup. They offer good rejection of multipath interference and can enhance the video signal quality.
2. Circular Polarized Antennas:
   • Cloverleaf Antennas: Cloverleaf antennas are popular circularly polarized (CP) antennas. They come in various designs, such as 3-leaf or 4-leaf clovers. Circular polarization helps mitigate signal polarization mismatches, leading to improved video quality and reduced signal fading during flight.
   • Patch Antennas: Patch antennas are directional and can provide increased range in a specific direction. They are often used as the receiving antenna on the VRX, pointing towards the direction of the drone or FPV vehicle.
3. Helical Antennas:
   • Helical antennas are directional and circularly polarized. They are often used when a higher gain, more directional signal is needed for longer-range flights. Helical antennas can have a higher degree of complexity but offer better performance in specific scenarios.
4. Patch Arrays:
   • Patch arrays consist of multiple patch antennas arranged in an array. They are commonly used for long-range FPV setups, providing both directional focus and gain.
5. Crosshair Antennas:
   • Crosshair antennas are another directional option that provides increased gain in a specific direction. They are suitable for medium to long-range FPV applications.
6. Helix Antennas:
   • Helix antennas are similar to helical antennas but are simpler in design. They provide circular polarization and are often used in FPV setups where compactness is essential.

It’s important to note that when setting up an FPV system, using a combination of different antenna types in a diversity setup (e.g., combining a linear antenna with a circular antenna) can enhance signal reception in various flight conditions. Additionally, the choice of antennas may depend on the specific requirements of the drone or FPV system and the pilot’s preferences.

Specification to be had in FPV cameras used for analog VTX

The FPV (First Person View) camera used in conjunction with an analog video transmitter (VTX) for drone racing and FPV flying is a critical component for providing real-time video feedback to the operator. Here’s a description of a typical FPV camera used with analog VTX systems:

FPV Camera:

1. Sensor Type:
   • FPV cameras often use small-sized sensors such as 1/3-inch or 1/4-inch CCD (Charge-Coupled Device) or CMOS (Complementary Metal-Oxide-Semiconductor). These sensors are lightweight and well-suited for the compact form factor of FPV drones.
2. Resolution:
   • FPV cameras generally have lower resolutions compared to consumer cameras, typically ranging from 600TVL (TV lines) to 1200TVL. The emphasis is on low latency and real-time video transmission rather than ultra-high resolution.
3. Lens Type:
   • FPV cameras commonly use wide-angle lenses, often with a focal length between 2.1mm and 2.8mm. The wide-angle helps provide a broad field of view, crucial for navigating obstacles and maintaining situational awareness during fast-paced flights.
4. Aspect Ratio:
   • FPV cameras typically have a 4:3 aspect ratio, which is common in the FPV community. Some cameras may support switchable aspect ratios to accommodate different preferences.
5. Field of View (FOV):
   • The field of view of FPV cameras is an important factor. A wide FOV, often exceeding 120 degrees, allows pilots to have a more immersive and comprehensive view of their surroundings.
6. Dynamic Range:
   • FPV cameras are optimized for fast changes in lighting conditions commonly encountered during drone racing. While dynamic range is essential, these cameras may not have the same level of dynamic range as consumer cameras designed for photography or videography.
7. WDR (Wide Dynamic Range):
   • Some FPV cameras come with Wide Dynamic Range capabilities to handle challenging lighting situations, such as flying from a shaded area into bright sunlight.
8. Weight and Size:
   • FPV cameras are designed to be lightweight and compact to minimize the impact on the drone’s overall weight and balance.
9. Power Requirements:
   • FPV cameras typically operate on low voltage and have a wide voltage input range. This is crucial for compatibility with the power distribution systems of FPV drones.
10. Mounting Options:
    • FPV cameras often feature standard mounting options, making them compatible with various drone frames. They are commonly mounted on adjustable brackets to allow pilots to customize the camera angle based on their flying style.
11. Low Latency:
    • Low latency is a critical aspect of FPV cameras to ensure that the video feed is as real-time as possible, minimizing the delay between the camera capturing the image and the pilot seeing it on their FPV goggles or monitor.

It’s important to note that the specifications and features of FPV cameras can vary among different models and manufacturers. Pilots often choose FPV cameras based on factors such as latency, field of view, and overall performance that align with their specific flying preferences and needs.

What are Analog VRX goggles and VRX Display?

Analog VRX (Video Receiver) typically refers to a dedicated device or module responsible for receiving analog video signals transmitted by the VTX (Video Transmitter) on a drone or FPV vehicle. This component is equipped with an antenna and can either be a standalone module or integrated into FPV goggles. The primary function of the analog VRX is to capture and process the incoming video signal, making it suitable for connection to various displays, including FPV goggles or external monitors. On the other hand, VRX Goggles, or Video Receiver Goggles, encompass FPV goggles equipped with built-in VRX functionality. These goggles serve as an all-in-one solution, integrating the Video Receiver to capture and display the analog video feed in real-time, providing an immersive experience for drone pilots during flights.

In the context of analog FPV systems, the term “VRX display” might be considered redundant as the VRX is specifically responsible for receiving and processing the video signal, while the display refers to the screen or monitor where the video feed is presented. The display is an integral part of FPV goggles, showcasing the real-time analog video feed to the drone pilot. Therefore, when dealing with analog FPV setups, the VRX and display components work in tandem within the FPV goggles to deliver a comprehensive and immersive experience for the operator during drone flights.

Connect the Antenna to the Matek SYS VTX

To connect the RHCP (Right-Hand Circular Polarized) 5.8G circular polarized mushroom antenna to the Matek SYS VTX, you’ll first need to use an MMCX to SMA RF Cable. Begin by identifying the MMCX connector on the Matek VTX and insert the MMCX end of the cable into the corresponding port securely. Ensure a firm connection to minimize signal loss. On the other end of the cable, connect the SMA connector to the RHCP 5.8G circular polarized mushroom antenna. This step usually involves screwing the SMA connector onto the antenna’s SMA port until snug. This configuration ensures a proper link between the VTX and the antenna, allowing for the effective transmission of analog video signals from your drone or FPV vehicle. It’s crucial to secure the connections snugly to prevent any potential signal interference or disconnection during flight, ensuring a reliable and stable FPV experience.

Connect power to the VTX

The input voltage of VTX I use can be given from 7 to 27. I supply the voltage from two 18650 Li-ion batteries. This is often used in RC cars and FPV drones. They are powered by Li-po batteries, and a Li-po battery from 2S to 6S can be connected to it. The antenna must be connected before powering the VTX. Otherwise the VTX will be damaged.

Connect the FPV Camera to the VTX

When connecting the camera, the voltage to be given to it should be checked. Most FPV cameras require a voltage of 5V. The Foxeer Razer mini camera I use can supply 4.5V to 25V.

• Connect 5V of VTX to VCC of FPV Camera.
• Connect GND of VTX to GND of FPV Camera.
• Connect Vid of VTX to VID of FPV Camera.

VTX Band, Channel and Output power setting

To configure the settings of your VTX (Video Transmitter), including Band, Channel, and Output Power, follow a general set of steps that may vary slightly based on the brand and model of your VTX. Typically, access the VTX menu through a button on the VTX itself or via a connected flight controller. Navigate through the menu options using the button, looking for settings related to Band, Channel, and Power. Select the appropriate Band for your region, such as “A,” “B,” “E,” “F,” or “R.” Within the chosen band, select a specific Channel numbered from 1 to 8. Finally, choose the desired Output Power for your flying environment, such as 25mW, 200mW, 600mW, or higher. Once configured, save the settings, usually by long-pressing the button or selecting a “Save” option in the menu. After saving, verify that the VTX is transmitting on the selected Band, Channel, and Power by checking the FPV feed on your goggles.

Always consult the user manual of your specific VTX for precise instructions, as details can vary between models. Additionally, ensure that the chosen settings comply with local regulations and frequency allocation standards to avoid interference with other FPV systems. Proper configuration of these parameters is crucial for optimal performance and adherence to legal requirements, contributing to a smooth and reliable FPV experience during your flights.

Configure band and channel settings on your VRX to match the VTX

When configuring the Band and Channel settings on your VRX (Video Receiver) to match the VTX (Video Transmitter), follow a standard set of steps, although specifics may vary based on your VRX model. Access the VRX menu using the designated button or interface as outlined in your VRX user manual. Navigate through the menu options, selecting the same frequency Band on the VRX as you set on the VTX; common bands include A, B, E, F, and R. Within the chosen band, select the specific Channel corresponding to the one configured on the VTX, usually numbered from 1 to 8. Optionally, some VRX units offer an auto-search feature to automatically scan and lock onto the strongest signal, aiding in ease of setup. After configuring the Band and Channel, save the settings per your VRX manual’s instructions.

Verification of reception is crucial; check your FPV goggles or display to ensure a clear video feed. If reception is suboptimal, consider fine-tuning the settings or adjusting the positioning of your FPV antennas. Always refer to the user manual of your specific VRX for precise instructions, as the interface and menu structure can vary between models. Additionally, ensure that the frequency settings align with local regulations and standards to avoid interference and ensure a stable and reliable FPV experience during your flights.

Conclusion

In conclusion, establishing a seamless and reliable analog video transmission system for RC cars and FPV drones involves a comprehensive setup that includes key components such as VTX, VRX, FPV camera, and antennas. Careful attention to detail during the connection process is crucial, from linking the RHCP 5.8G circular polarized mushroom antenna to the Matek SYS VTX using an MMCX to SMA RF Cable to the meticulous wiring of power and video signal connections between the VTX and FPV camera. Configuring the VTX and VRX settings, including Band, Channel, and Output Power, plays a pivotal role in ensuring optimal performance and compliance with local regulations. This comprehensive approach, encompassing hardware connections and thoughtful configuration, sets the foundation for an immersive and responsive FPV experience, making it well-suited for a range of applications, from RC car enthusiasts to FPV drone racing enthusiasts, all within the specified voltage and frequency parameters to guarantee a safe and enjoyable flying experience.