User's Manual Part 1

CL1TC-4 400W DVB-H Transmitter Product Description
Product Manual, Rev. 1 15
2.3.4 Modulator
T
he modulator includes
DVB-H modulator
Amplifier
Bandpass filter
GPS receiver
I/O extension board
System controller
Power to the modulator is protected using a UPS power backup (see Figure 2-6
). This will
ensure site monitoring will continue during a power outage as well as continued signal
generation to ensure a fast recovery time once power is restored.
2.3.4.1 DVB-H Modulator
The module performs DVB-H signal encoding,
OFDM waveform generation and has
the ability to synchronize with other stations to provide Single Frequency Network
(SFN) operation.
The module performs the frequency conversion of the OFDM signal into the required
L-Band channel frequency, to drive the high power amplifier (HPA).
Digital Linear and Non-linear pre-correctors provide compensation for the group
delay introduced by the HPA output filter and the non-linear distortions produced by
HPA.
The DVB-H Modulator receives a MPEG-2 structured Transport Stream on the ASI input or
an IP encapsulated MPEG-2 structured Transport Stream on either of the RJ-45 Ethernet
ports. The IP input is according to MPEG PRO CoP #3 FEC / SMPTE 2022 protocol.
The modulator converts the digital input streams (ASI or IP) to an OFDM waveform in
accordance with DVB-T/H standards. A direct conversion process provides a single analog
RF output from 1670 MHz to 1675 MHz, suitable for amplification in the high power amplifier
(HPA).
Digital linear and non-linear pre-correctors (pre-distorters) significantly improve the
performance of the high power amplifier. The Non-linear pre-corrector compensates for the
HPA non-linearity and is able to provide separate adjustment for the low and high frequency
shoulders of the wide channel spectrum. The Linear pre-corrector compensates for the
group delay created by an output filter.
2.3.4.2
Amplifier
The amplifier provides up to
20 dB of gain, allowing the modulator to provide an RF output
power level from -10 dBm to 0 dBm with shoulders >
55dBc.