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.
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
modulators. Other sub-divisions may be based on the kind and number of inputs and channels, output frequency range, support for HDCP protocol etc.
The HDCP (High-bandwidth Digital Content Protection) protocol developed by Intel is designed to secure copyrighted multimedia files by encrypting high-definition signals, etc. HD-DVD, Blu-Ray, and thus protect content against copying at every stage of transmission. Subscribers pay a fixed annual fee and a variable extra rate depending on the number of produced devices.
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.
The modulators with HDMI inputs provide excellent solutions for hospitals, stores and shopping malls, supermarkets and electronics stores in which HD content from one or two sources should be delivered to multiple TVs. Such devices are also ideal for MATV/SMATV systems integrated with video surveillance systems - they can distribute the CCTV signal from a modern DVR, containing up to 16 images from security cameras. The images can be watched on any HD television connected to the antenna system. The modulators used for this purpose do not need to support the HDCP protocol.
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
|Number of channels
|720x576_50i PAL), 720x480_60i (NTSC),
|720x576_50i (PAL), 720x480_60i (NTSC),
| 50-860 MHz
|Max. output level [dBμV]
High-definition signal with resolution up to Full HD can be distributed within RF network with the use of one-channel modulator Signal-420 R86700
. It makes a perfect alternative for HDMI distribution network based on HDMI switches and cables. The modulator has HDMI and RF inputs. The RF input provides RF loop function that is used to combine the modulated signal with other TV signals.
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)
The MI520P R81609
transmodulator eliminates the need for an NVR. The device receives IP stream from the IP cameras with bit rate up to 80 Mbps and converts it to two configurable DVB-T COFDM, DVB-C/J.83B/ISDB-T multiplexes, with a maximum bit rate depending on the selected standard. The administrator of the system selects the required channels from the IP stream and creates any two DVB-T/DVB-C/J.83B/ISDB-T multiplexes (MUXes). The output RF signals are provided to televisions connected to the antenna system.
A video presenting the Terra MI520P R81609
modulator along with the installation procedure
Video from the IP CCTV cameras is enters the MI520 R81609
modulator and is distributed from its output in the form of DVB-T signal in a SMATV system. The image from each camera is available in the system as a separate DVB-T channel.
If we want to introduce the signals from AHD or IP cameras into an antenna installation, we can use the cheapest digital HDMI modulator on the market - DVB-T (Full HD 1080P / 60Hz) R86111
. The device allows for cost-effective integration of CCTV video surveillance systems with shared/(S)MATV antenna systems to distribute Full HD (1920x1080) signal from the HDMI output of a DVR or NVR to many televisions connected to the RF distribution network based on common RF splitters, taps, and coaxial cables.
HDMI to DVB-T Encoder/Modulator (Full HD 1080p/60Hz) R86111
encodes and modulates Full HD (1920x1080-60p) signal provided to its HDMI input to RF signal in accordance with DVB-T standard (COFDM). The output DVB-T multiplex contains one channel modulated by the source signal. This way the source signal from a DVR/NVR can be distributed to multiple televisions connected to the antenna system. It makes an attractive alternative to installations based on HDMI splitters and cables.
View of the HDMI to DVB-T R86111
encoder/modulator (RF OUT side).
The DIP switches allow the user to select a TV channel.
In the example above, the digital Signal R86111 modulator has beeen provided with Full HD video signal coming from the HDMI output of the DVR. The output RF signal in DVB-T standard is combined by the E2094 combiner with the terrestral TV and radio signals. The signals are received by the A2670, A0710, and A0221 antennas (of course, the antennas can be replaced by other models operating in FM, VHF, bands, depending on the local reception conditions). The outdoor antenna amplifier TERRA MA080L R82022 has three band inputs: FM (88-108 MHz), VHF (174-230 MHz), and UHF (470-790 MHz). Each path of the amplifier has individual gain adjustment, and the UHF path is equipped with LTE 800 filter. The MRP-508 R68508 multiswitch provides 12 VDC supply voltage option that has been activated (switched on) for powering the MA080L R82022 amplifier. The RI-2/1 F E2094 combiner passes the DC voltage to the amplifier.
Application of digital HDMI-DVB-T modulator with additional HDMI output
The MHD002P R86104
modulator is a multifunctional device that encodes and modulates the input HDMI signal with resolution up to Full HD (1920x1080-30p) into DVB-T COFDM RF channel. In the MHD002P R86104
model, the HDMI output can transfer the input HDMI signal to a local monitor
Example of using the Terra R86104
MHD002P digital modulator.
The source signal (from Blu-Ray player) is modulated to DVB-T channel
and can be viewed on any TV connected to the distribution network.
The original HDMI signal is directly monitored on the "local" TV.
An example of installation using a digital HDMI-DVB-T modulator
RF distribution sytem implemented in one of electronics stores. Thanks to the application of the Signal-751 R86751 DVB-T modulator, the commercials in HD quality are distributed to tens of televisions located throughout the store. Additionally, the analog TV modulator TERRA MT-47 R871747 allows for distribution of SD video from any A/V source. The both signals are combined and amplified by the MA-024 R821101 broadband amplifier.