FROM EDN EUROPE: 3/6-GHz signal generator features twin channels

You can generate signals to test all of the major mobile radio standards, including GSM EDGE, and 3GPP (Third-Generation Partnership Project) FDD (frequency division duplexing), as well as to produce complex multicarrier signals for base-station-amplifier tests with Rohde and Schwarz's SMU200A vector-signal generator (Picture). The instrument's architecture features two complete signal paths: two signal sources and two (or one) I/Q baseband processors. It lets you perform applications that previously called for two generators with only one generator. The instrument is modular both in concept and in construction; you set up the signal path you require by interconnecting functional blocks on a graphical user interface. The primary RF path can come with a source running at 2.2, 3, 4, or 6 GHz maximum; the second can run at 2.2 or 3 GHz. At baseband, you can specify two real-time signal-generation or arbitrary-waveform generators. The device includes digital addition of the baseband paths, and you can set up a frequency offset between the two. Having two paths in one instrument means that the device can internally resolve synchronisation issues. You can, therefore, create wanted and interfering signals in one unit. Or, stored arbitrary data from one source can generate a fixed multicarrier signal, and you can insert a signal channel of "active" data from the other signal path. The instrument includes online and context-sensitive help.

R&S quotes typical phase-noise performance of –135 dBc, measured in a 1-Hz bandwidth 20 kHz away from a 1-GHz signal. Power levels are –145 to +26 dBm with a fully electronic (wearfree) attenuator. The company quotes level uncertainty of less than 0.5 dB to as much as 3 GHz but says that, in many tests, level repeatability is extremely important and assesses it at 0.05 dB. The instrument meets the requirements of adjacent-channel power measurements for today's base-station designs and has margins to handle even more stringent level specifications; the company quotes a typical ACLR (adjacent-channel leakage-ratio) figure of 70 dB. You can use the 200A for repetitive or production measurements, thanks to its frequency-setting time of 3 msec; you control it over a GPIB or Ethernet connection. Depending on options, prices for the SMU200A start at €22,500.

At the other end of the price scale, R&S has introduced the second device in its portable, modular-construction "Smart" instrument series. The SM300 signal generator covers 9 kHz to 3 GHz. It lets you generate digital signals for mobile-radio standards, and you can use it as a general-purpose signal source. I/Q bandwidth is 40 MHz, and phase noise is better than –95 dBc, measured as for the SMU200A. The instrument can produce levels reaching 13 dBm with a level uncertainty of less than 1 dB. As with other "Smart" instruments, R&S builds the 200A around a USB backplane, and you control it externally by a PC via a USB connection. These features add up, R&S says, to a unique specification for a generator in this price range, which is €6500.

Rohde and Schwarz, +49 89 4129 11765, www.rohde-schwarz.com.