DekTec DTE-3114 IP to 4x QAM - Manual (Page 4)

DTE-3114 – Networked Quad QAM Modulator
USER MANUAL
4
1. Introduction
1.1 General description
The DTE-3114 is a compact four-channel QAM modulator with Transport Stream over IP (TSoIP)
inputs and a directly synthesized VHF/UHF output. The device can operate in DVB-C, J.83 Annex B
and J.83 Annex C mode, with support for the various QAM constellations and interleaver modes.
The unit accepts unicast and multicast streams over its Gigabit-Ethernet port, and modulates the four
TSoIP streams to four adjacent channels anywhere between 32 and 1006MHz. Key features include
de-encapsulation of UDP or RTP, accurate timing reconstruction using innovative algorithms to
overcome IP jitter, as well as error correction according to SMPTE 2022-1.
A significant innovation in the DTE-3114 is support for Power over Ethernet (PoE). When used with a
PoE compatible network, the modulator does not require a separate power feed, as it can draw its
power from the Ethernet network. A power jack is still offered where PoE is not available.
The DTE-3114 supports SNMP management and has an easy-to-use web-based user interface for
configuration purposes, as well as retrieving status information and performance statistics. The LCD
status display shows the user-programmable device identifier, current configuration information and
IP/MAC address.
1.2 Block diagram
Figure 1 shows the functional block diagram of the DTE-3114. Each of the four channels starts with
an IP filter that selects IP packets for the configured unicast or multicast address. The resulting IP
packets are converted to a Transport Stream, which will typically be a Multi-Program Transport
Stream (MPTS). In this block any lost packets are recovered in the FEC decoder and the input TS rate
is accurately estimated. Buffering with a configurable delay is included to be able to tolerate IP jitter.
Figure 1. Functional block diagram of the DTE-3114.
After reconstructing the Transport Stream its rate is converted to the rate corresponding to the
modulation settings (QAM constellation, symbol rate). Rate conversion comprises inserting null
packets and adjusting the PCR time stamps. Then the packets are QAM modulated according to the