User's Manual

Table Of Contents

18 2. System Description

The Event-HD ODU RF Up/Down Converter provides the interface to the antenna. The

transmit section up converts and amplifies the modulated Intermediate Frequency (IF) of

350 MHz from the IF Processor and provides additional filtering. The receive section down

converts the received signal, provides additional filtering, and outputs an IF of 140 MHz

to the IF Processor.

The Event-HD digital radio modem performs QPSK, 16-QAM, 32-QAM, 64-QAM, and 128-

QAM modulation and demodulation of the payload and forward error correction using

advanced modulation and coding techniques. Using all-digital processing, the IF Modem

uses robust modulation and forward error correction coding to minimize the number of

bit errors and optimize the radio and network performance. The IF Modem also

scrambles, descrambles and interleaves/deinterleaves the data stream in accordance

with Intelsat standards to ensure modulation efficiency and resilience to sustained burst

errors. The modulation will vary by application, data rate, and frequency spectrum. The

highest order modulation mode supported is 128 Quadrature Amplitude Modulation

(QAM). Table 2-5 summarizes the TCM/convolutional code rates for each modulation type

supported by the Event-HD.

Table 2-5. Event-HD TCM/Convolutional Code Rates

Modulation Type Available Code Rates

QPSK 1/2, 3/4, 7/8

16-QAM 3/4, 7/8,

32-QAM 4/5, 9/10

64-QAM 5/6, 11/12

128-QAM 11/12

The major functions of the SDIDU

can be summarized as follows:

• I/O Processing – Event-HD digital radio comes with a standard I/O capability that

includes support for up to 16xT1/E1 and 2x100Base-TX user payloads, 2x100Base-TX

for SNMP, and voice orderwire. In addition, option cards for DVB-ASI,

DS-3/E3/STS-1, 1-2 x STM-1/OC-3, and 4xDS-3/E3/STS-1 may be added. The Event-

HD architecture is flexible and allows for the addition of other I/O types in the future.

• Switch/Framing – The Event-HD digital radio includes an Ethernet Switch and a

proprietary Framer that are designed to support 1+1 protection switching, ring

architecture routing, and overall network control functions.

• Network Processor – The Event-HD digital radio includes a Network Processor which

performs SNMP and Network Management functions.

• Modem/IF – The Event-HD digital radio modem performs forward-error-correction

(FEC) encoding, PSK/QAM modulation and demodulation, equalization, and FEC

decoding functions. The IF chain provides a 350 MHz carrier and receives a 140 MHz