USB vector signal generator spans 100 MHz–2.5 GHz for under $500

May 26, 2015 // By Graham Prophet
Signal Hound, maker of USB-based RF test and measurement products, recently announced announced a vector signal generator that is USB-powered and weighs just 130 grams; the VSG25A costs $495 and features a frequency range of 100 MHz to 2.5 GHz with digital pattern generation.

Output amplitude is -40 dBm to +10 dBm, with 100 MHz of modulation bandwidth. The VSG25A covers most telecom frequencies and two major ISM bands (902 MHz-928 MHz and 2.4 GHz-2.5 GHz). Covering FM broadcast bands, it can be used down to 80 MHz with reduced amplitude accuracy.

Digital modulation comes as part of the VSG25A. Specific protocols are not supported—however, the modulation behind those protocols is supported. These include BPSK, QPSK, DQPSK, OQPSK, π/4 DQPSK, 8PSK, 16PSK, 16QAM, 64QAM, and 256QAM. Symbol rates from 4 kHz to 45 MHz are supported.

Noise power ratio testing for telecoms; measuring intermodulation distortion is critical for the telecommunications industry. Two-tone IP3 testing is useful for narrowband applications, but does not do a very good job of simulating actual channel conditions on a multi-carrier system, which more closely resembles bandwidth-limited white noise. Noise power ratio (NPR) testing traditionally consists of a broadband Additive White Gaussian Noise (AWGN) source covering the entire bandwidth to be tested, and a deep, narrow notch filter somewhere within this bandwidth (typically 10% or less of the total bandwidth). The noise power ratio is the ratio of the signal power density to the power density of the notch, which is a combination of thermal noise and intermodulation products. While a band pass filtered noise source and notch filter may work in some cases, there is a much easier way that also adds greater flexibility. A modern vector signal generator is the foundation of up-to-date NPR testing. With a 100 MHz of bandwidth and capability of producing synthetic noise sets of 1000+ tones (having random-phase relationships combined with the absence of tones in the test pattern’s centre), the VSG25A offers a solution. Until now, these generators would cost thousands or even tens of thousands of dollars.

VSG25A sells for $495 or local equivalent subject to shipping, import taxes, and currency fluctuations. The purchase price includes software. An API (Application Programmer