Deploying a Packet Based Bidirectional TDD Telemetry Link System

Abstract

Conversion of telemetry links to packet-based Ethernet communications is underway with both unidirectional and bi-direction links being deployed. For both test range and other applications, the user community has embraced the simplicity of bridging Ethernet test article and ground networks. With bidirectional packet based solutions, the adaptation of existing telemetry physical layer systems is often preferred. Most of these applications use Frequency Division Duplex (FDD) as long as co-site interference can be mitigated and two frequencies are obtained. A Time Division Duplex (TDD) solution requires only a single frequency and has no co-site bidirectional inter-link interference. The TDD approach requires some amount of design effort by the communications hardware provider to convert to a switched based system, though once done the benefits over FDD are realized by the end user. A deployed TDD bidirectional Ethernet system is presented and changes to the streaming telemetry system.