A video transmitter (also known as a wireless video transmitter , AV transmitter, or audio video transmitter ) is a device that allows you to wirelessly transmit audio or video signals from one location to another.
There is an enormous range of transmission methods for such devices. Just like analog ( radio ), digital (wide spectrum, WLAN , ultra-broadband) and digital with cable (power line communication). There are other, not so widespread methods, such as those that use existing Ethernet networks.
Most video transmitter systems consist of three components, a transmitter , a receiver and a remote control system (also known as magic eye or IR blaster). The transmitter is responsible for transmitting the signal from the connected signal source. The receiver then forwards the received signal to the connected television set. The remote control relay then makes it possible to work with the infrared remote control of the connected device.
Analog systems without cables
Analog systems have the advantage that they can be manufactured inexpensively because the audio and video signals are simply modulated in the 2.4 GHz or 5.8 GHz range. They have the detrimental effect of causing a reduced bandwidth of the local WiFi networks and, in some cases, of causing interference in the images of the video broadcast signal. To avoid this, some video transmitters are now using a process that expands the spectrum and can work well with wireless networks and share the available bandwidth.
There are normally four FM transmission channels A, B, C and D with stereo audio at 6.0 MHz and 6.5 MHz as subcarriers to the basic video tape. These different channels can often be used to turn off the effects on nearby WiFi networks.
The returning remote control channel is usually rated at 433.92 MHz, modulating carrier waves over 34 kHz to 45 kHz in the infrared. Amplitude shift keying (ASK) with the on-off keying schemes ((OOK)) such as RC5 and RC6, work best with the RF link, since the receiver has a data slicer and an automatic one Automatic gain control (AGC) with Manchester coding used.
Analog wireless video transmitters have a typical working distance of up to 60 meters (clear line of sight) with DVD quality (720 × 576 video resolution) and stereo sound.
Digital systems without cables
Digital video transmitters have quickly become the most widely used solutions, combining the use of a system on a chip (used for audio and video encoding and decoding) with a carrier for signal transmission such as extended spectrum, WiFi and ultra-wideband.
The first digital video transmitter models typically broadcast DVD quality, but newer models are also capable of up to 720p and 1080p HD resolutions.
Spread spectrum is a process that deliberately distributes a signal across the frequency response, resulting in a wider bandwidth. For the video transmitter market, this means that interference with WLAN will decrease significantly.
WIRELESS INTERNET ACCESS
Video transmitters that work with existing WLANs have already been developed and use another interference-free method for the transmission of sound and images. The available spectrum is used by the video transmitter and all other connected devices, although older network methods can cause problems.
Ultra-wideband is a technique to distribute information over a wide bandwidth (> 500 MHz) and is usually used for short ranges (10 meters or less) where a simple connection between the source device and monitor or television is required. It is therefore generally not suitable for video transmitter applications that are to transmit a signal to another room.
Various video transmission methods , such as wired communication and HDBaseT , which were previously developed to use existing networks, serve a wired video transmitter solution for audio, video and Internet connections within the house.
Power line communication
Video transmitters with wired communication use existing power lines to transmit the audio and video signals. They essentially correspond to powerline communication .
In 2010 a new standard for wired applications for end users was introduced, which was named "HDBaseT", a technology and commercial connection method for the transmission of uncompressed and highly defined (HD) video, audio, home network, Ethernet, USB - and some control signals via a cable of a common category (Cat5e or higher) with a common plug (RJ45).
The wireless transmission requires that a product is tested for relevant permitted standards and generally limited to 100 mW. A license is required for more powerful devices used in the broadcast industry. The exception for a license is distribution via LAN or similar IP technologies such as the Internet. Supervision is carried out by the Federal Communications Commission in the USA, which is responsible for the bandwidth efficiency of radio.