When it comes to choosing the best digital TV modulator, which would meet your needs, you should pay attention to some important issues: how easy the product is to use, what features each model has and how well it works. The quality of picture and sound is satisfactory and how well the product works with your other equipment is a baseline for most consumers; however there are other options, features, and mitigating factors that also drive consumers to more expensive units. The fact being is TV Modulators are not all one in the same; one of the biggest factors consumers face is which kind of encoding chip is in the unit; the chip is one of most important pieces as its the "engine" that makes the vehicle go.
Best Digital TV Modulator
We would like to recommend a handful of interesting options from the Thor Broadcast catalog to illustrate the options from Pro-DVB down to Prosumer grade units:
Support CC (Closed Caption) EIA608 (from CVBS input)
1-4 CATV RF Output up to 4 Adjacent channels
QAM-256/64, DVB-T & ATSC formats available
Fully IP Control and Network Management through browser
Front Panel LCD local control
IPTV Output Unicast or Multicast IGMP UDP, RTP / RTSP
ASI Output multiplexer with cherry picking
Low Latency available 300/500/800ms delay via different modes - IP will always be closer to 800ms due to the decoding (these values are end to end, not just the encoding speed)
Dolby AC3 or MPEG1/2 Audio Encoding
MPEG2 or MPEG4 H.264 Video Encoding
Firmware for ATSC, DVB-T, DVB-S2 Available
VCT (Virtual Channel Table) support for DVB-C and ATSC
This unit has 2 HDMI and 2 SDI inputs with RF CATV QAM and ATSC output. You can broadcast over existing coaxial cabling to an unlimited number of televisions in FULL HD
Features
Convert 2 HDMI & 2 SDI HD Video Content programs to Perfect QAM Channels simultaneously
Any 2 HDMI & 2 SDI Inputs up to 720p/1080i/1080p
Licensed HDMI inputs
2 HDMI and 2 BNC cables FREE
Support DD AC3 (2.0/5.1/7.1) passthrough(for HDMI interface only)
Support CC (Closed Caption) EIA608,and EIA708 on SDI’s
1-4 CATV RF Output up to 4 Adjacent channels
QAM-256/64, DVB-T, & ATSC formats available
Fully IP control and Network Management through browser
Front Panel LCD local control
IPTV Output Unicast or Multicast IGMP UDP/RTP/RTSP
ASI Output with multiplexer cherry picking
Low Latency available 300/500/800ms delay via different modes - IP will always be closer to 800ms due to the decoding (these values are end to end, not just the encoding speed)
Dolby AC3 Audio encoding and Doby AC3, 5.1 Pass-Trough
MPEG2 Video or MPEG4 H.264 Encoding
Firmware for DVB-C, ATSC, DVB-T, DVB-S2, ISDB-T Available
VCT (Virtual Channel Table) support—for DVB-C ATSC and DVB-T
This Device has 12 Indpepndent SDI to CATV RF Video inputs.This unit is a Coax Modulator and IP Video Encoder. It Provides IPTV MPEG2 and H.264 Encoding. With this Device you can provide SDI Video distribution over COAX and IP
Features
12 HD-SDI inputs with MPEG2 & MPEG4 AVC/H.264 Encoding
1 RF tuner input for re-mux The tuner - base model support ATSC but QAM or DVB-T or ISDB-T tuner could be requested
256 IP(DATA1 port only) input over UDP and RTP protocol
MPEG1 Layer II, MPEG2-AAC, MPEG4-AAC, Dolby Digital AC3 (2.0) encoding AC3 (2.0/5.1) passthrough
16 groups multiplexing /Scrambling/ DVB-C QAM or ATSC modulating
8 groups multiplexing / DVB-T modulating---Optional
16 MPTS IP (DATA2 port only) output over UDP, RTP/RTSP
8 MPTS IP (DATA2 port only) output over UDP, RTP/RTSP--only for DVB-T RF out
PID remapping/ accurate PCR adjusting/PSI/SI editing and inserting
Thor Universal multi-channel SDI and HDMI Modulator with QAM, ATSC, DVB-T, or ISDB-T coax RF output
Features
8 Independent HDMI and SDI Inputs - (individually selectable for each of the 8 channels you can output)
HDMI is HDCP compliant for use with any source
SDI Inputs include support for Closed Caption 708
Outputs 8 separate Clear CATV RF channels QAM / ATSC - 8VSB / DVB-T / ISDB-T (selectable in the GUI)
RF output on each of the 8 RF channels can be individually set to a frequency and modulation standard (2 on QAM, 3 on ATSC, 4 on ISDBT, etc)
DVB-C Annex A and B - QAM 64, QAM 256
Supports full HD video up to 1080p/59.94/60, other resolutions included are 1080i, 720p, 480i also supported
Low Latency supported; 2 different latency settings - 500/1000ms
Video encoding rate up to 25Mbps
MPEG2 Video Encoding
Dolby AC3 and MPEG1 Layer 2, & AAC audio encoding
VCT - Virtual channel number and Name supported
Frequency - 50Mhz to 900Mhz
NMS web interface controllable
Easy to use web Gui Interface (setup and status)
LED's Status on front panel shows HDMI in blue or SDI in green for easy to see video detect link
LCD Display and front panel control buttons for setup, control and status
Powerful processing with the best MPEG2 video encoding chip
First High Density HDMI and SDI input modulator on the market
Lowest cost per channel in perfect HD resolution for any application from Live Sports, House of Worship, Concerts, Theaters, Malls, Airports, Hotels, Military, Private Enterprise
This Modulator is an All In One Device Integrating HD MPEG2 encoding with AC3 Dolby Audio and Closed Captioning Input. Device Converts HD Audio and Video signals from any device into DVB-C/T / ATSC / ISDB-T RF Output. This Unit is a Digital HDMI Encoder and RF CATV ATSC Modulator with Closed Captioning Input and Network Ethernet browser contol.
Features
HDMI Input - HDCP compliant ( works with any HDMI device )
10/100 Ethernet NMS port for control, setup, and monitoring
RF output could be set to any CATV format as QAM, ATSC, DVB-T, or ISDB-T
RF output power is +24dbmv; enough for distributing HDTV video to 100's TV over the existing coax cable network
RF power could be controlled over the network via NMS Gui (Proprietary)
MPEG2 video encoding
AC3 Audio encoding
Video bit rate 1-19.5Mbps can be managed over the network
Supports any CATV RF agile channels from 57-1000Mhz, channels 2 -135,
Supports output resolutions up to 1080p
Easy to set up via NMS.
Small size and lightweight
Includes wall-mount type rack ears
Install multiple units onto your TV system
The powerThe supply is included
The HDMI cable is included
Additional optional accessories:
H-PS-12X16 - Rackmount 19" Power Supply 16 port 12V 1.5A DC
The video output from the camera is fed into the video input of the modulator, which is set to an RF channnel where you wish the video to appear on the televisions in the system. When you think about it, a modulator is a tiny, cheap, low power TV station capable of broadcasting on a selected UHF or cable TV channel. It takes a baseband video signal and a monaural audio signal and converts them to a broadcast RF television signal on an off air UHF channel or a cable television channel. Modulators allow multiple baseband video sources to work with the same coax. A modulator is a device that performs modulation. A demodulator (sometimes detector or demod) is a device, which performs demodulation - the inverse of modulation. A modem (from modulator–demodulator) can perform both operations.
Why do you need a Digital TV Modulator
Digital modulation is used to transfer a digital bit stream over an analog channel at a high frequency. This enables users to transmit signals generated in a digital circuit across a physical medium. This is possible because digital signals can be handled with higher security and digital systems are widely available. The main advantages of the digital modulation over analog modulation include available bandwidth, high noise immunity and permissible power. Digital Modulation provides more information capacity, high data security, quicker system availability with great quality communication. Hence, digital modulation techniques have a greater demand for their capacity to convey larger amounts of data than analog modulation techniques.
Why do you need a Demodulator
Demodulation is the process of recovering the original signal from the modulated wave. At the broadcasting station, modulation is done to transmit the audio signal over larger distances to a receiver. When the modulated wave is picked up by the radio receiver, it is necessary to recover the audio signal from it. This process is accomplished in the radio receiver and is called demodulation. The wireless signal consists of radio frequency (high frequency) carrier wave modulated by audio frequency (low frequency). The diaphragm of a telephone receiver or a loud speaker cannot vibrate with high frequency. Moreover, this frequency is beyond the audible range of human ear. So, it is necessary to separate the audio frequencies from radio- frequency carrier waves.
How does a Digital TV Modulator work
In digital modulation, an analog carrier signal is modulated by a discrete signal. Digital modulation methods can be considered as digital-to-analog conversion and the corresponding demodulation or detection as analog-to-digital conversion.
The most fundamental digital modulation techniques are based on keying:
PSK (phase-shift keying): a finite number of phases is used
FSK(frequency-shift keying): a finite number of frequencies is used
ASK (amplitude-shift keying): a finite number of amplitudes is used
QAM (quadrature amplitude modulation): a finite number of at least two phases and at least two amplitudes is used
In all of the methods mentioned above, each of these phases, frequencies or amplitudes has assigned an unique pattern of binary bits. Usually each phase, frequency or amplitude encodes an equal number of bits. This number of bits comprises the symbol that is represented by the particular phase, frequency or amplitude.
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