Rohde & Schwarz demonstrated a complete system for generating and analyzing user-defined and standard independent Orthogonal Frequency Division Multiplex (OFDM) signals at its booth (2407) at the International Microwave Symposium. The system consists of R&S signal generators and a signal analyzer using OFDM specific measurement software and covers microwave frequencies up to 40 GHz with a signal bandwidth up to 100 MHz.

The OFDM modulation scheme is getting more and more important. It is used by an increasing number of current and emerging wireless systems such as LTE and WiMAX. Moreover existing and upcoming broadcast standards such as DVB-T or DVB-T2 employ OFDM. In aerospace and defense applications there is a trend to use OFDM signals as well, and in most cases these signals differ from existing and known standards, so are often proprietary.

To address these growing requirements, Rohde & Schwarz developed a generic OFDM measurement software, R&S FSQ-K96. This software allows to analyze any kind of OFDM or OFDMA based signal with any PSK or QAM modulation scheme. In addition to center frequency and level, general OFDM parameters such as guard interval and FFT length are adjustable. The structure of the preamble, position and value of the pilots, and position and modulation type of the data carriers can be user-defined as well. With this analysis tool design engineers now have the possibility to analyze their own user-defined OFDM signals. Furthermore it is possible to generate a waveform file for R&S signal generators. Thus the R&S FSQ-K96 option is an invaluable tool as it supports development engineers in the analysis of pro¬prietary signals and in the initial phases of forthcoming OFDM standards.

In addition to the applications mentioned above, the software is well suited to working with signals for systems being proposed by the Multimedia over Coax Alliance (MoCA). MoCA also uses non-standard OFDM signals and is developing specifications for home networking over coaxial cable, the most common interconnect medium for connecting residential entertainment equipment such as televisions and cable set-top boxes. The alliance’s goal is to allow home networking on existing coaxial cable in the 1 GHz microwave band at 100 Mb/s using OFDM modulation, without the need for new connections.

The demonstration at IMS 2009 featured a complete system for generating and analyzing non-standard OFDM based MoCA signals. The R&S SMBV100A vector signal generator generates the MoCA signal and an external mixer with LO input provided by the R&S SMF100A microwave signal generator upconverts the signal to microwave frequencies. The R&S FSQ signal analyzer downconverts and analyzes the signal using the R&S FSQ-K96 software. It is the only such system available for these applications.