Digital DVB-T modulators – assortment and applications

The conversion of baseband audio-video (A/V) signals to radio frequency (RF) channel is called modulation. The process allows for the distribution of signals coming from all kinds of sources, such as computers, DVD players, security cameras etc. through antenna systems. The device used for this purpose (modulator) is equipped with one pair or a set of A/V inputs (SCART, RCA, HDMI) and an RF output. The output signal injected into the antenna system is available in the distribution network as an additional TV channel (or multiplex - in the case of a DVB-T modulator) that can be received by any suitable television connected to the RF network.

RF modulators can be divided into several groups, depending on the character of the output signal. Modulators with analog TV channels are coming out of general use, replaced by digital DVB-T and DVB-C modulators. Other sub-divisions may be based on the kind and number of inputs and channels, output frequency range, support for HDCP protocol etc.

Digital modulators with DHCP support cost more, but thanks to the support for the protocol, the source signals may come from a variety of devices: multimedia players, DVD or Blu-ray players, PCs, STBs. Generally, digital modulators have a number of advantages associated with the distribution of the signals in digital form (good and identical image quality in the whole network, possibility of distributing HD content, effective use of RF spectrum - several A/V signals can be distributed within one RF channel). DVB-T modulators converting the audio/video signals provided through A/V (RCA) connectors ensure the standard SD quality, and DVB-T COFDM modulators equipped with HDMI inputs can distribute over an RF network even Full HD 1920x1080_60p content.

HDMI modulators are ideal for hospitals, shopping malls, supermarkets or electronics stores, where content from one or two sources is delivered to multiple TV sets. The device can also be used in RF/SAT system integrated with monitoring systems – it can be used to transmit signals from a DVR (up to a dozen or so camera images) to all terminal outlets.

RF modulators are not used only in antenna systems (MATV/SMATV). Sometimes, the distribution of signal A/V signals via coaxial cable (after conversion to RF signal) is much simpler and less expensive than other solutions - especially in situations where the signal has to reach multiple points (receivers). An example is an electronics store, where an HDMI -> DVB-T modulator eliminates the problems with splitters and tens of HDMI cables that could be used for the distribution of the demonstration content to tens of televisions.

The table below shows differences between some DVB-T modulators: Signal-420 R86700, WS-7992 R86702, and WS-7990 R86704.

Digital HDMI-DVB-T modulator R86301 is dedicated to small systems in single-family houses. Compact size, competitive price, simple installation, and intuitive configuration using buttons on the front panel are features that every installer and user will appreciate.

Signal-420 R86700 is an excellent substitute for systems based on splitters and HDMI cables. It has HDMI and RF input, which can be used to sum the output signal with other TV signal.

WS-7992 R86702 and WS-7990 R86704 multi-channel modulators are multipurpose devices that convert HDMI or baseband A/V signals into DVB-T multiplexes. Additional RF input (ANT IN) can be used for combining the output RF signal with other TV signals.

The injection of the video information from IP CCTV cameras into an RF distribution network (a private or shared antenna system, (S)MATV/CATV network etc.) requires application of intermediate devices. In the case of using an NVR with HDMI output, these usually are Full HD HDMI DVB-T/C modulators. Installers can choose from single-channel and multichannel (max 4) models.

In the case of direct introduction of IP camera signals into the RF/SAT system, the MI520P R81609, mix440 R81611 or miq440 R81631 IP modulator can be used. The MI520P R81609 receives an IP stream with a maximum bit rate of up to 80 Mbps (e.g., from a dozen or so IP cameras) and creates any 2 adjacent multiplexes with the maximum bit rate characteristic of the standard specification. Meanwhile, the mix440 R81611 and miq440 R81631 modulators receive an IP stream with a maximum bit rate of up to 200 Mbit/s (e.g., from a dozen IP cameras) and create any 4 adjacent multiplexes with a maximum throughput characteristic of the specification of the standard. The system administrator selects channels of interest from a given IP stream, then creates any two packets (MUXes) in the selected standard: DVB-T, DVB-C.

If you want to inject signals from AHD or IP cameras into a TV/SAT system, you can use one of the above modulators (Digital modulators table) HDMI-DVB-T (Full HD 1080P/60 Hz). The device is used in integrated RF/SAT systems for CCTV monitoring, it can be used to transmit signals from a DVR or NVR to multiple TV receivers via coaxial cable. Signal digital modulators enable conversion of the incoming Full HD (1920x1080-60p) signal fed to HDMI to the DVB-T COFDM standard, thus providing an excellent alternative to systems based on splitters and HDMI cables.

The Signal R86301 modulator is a multifunctional device that modulates the input signal in Full HD resolution (1920x1080-30p) fed to the HDMI connector in DVB-T COFDM standard. The diagram below shows distribution of HD signal from any HDMI source and terrestrial DVB-T2 TV in coaxial cable with an example application of Signal R86301 modulator.