The Synth300S and Synth300D are 1- to 300-MHz single/dual-channel direct digital synthesis (DDS) PC cards that come economically priced at $1495/$1995, respectively. Each is separately programmable in increments of about 0.223 Hz. Besides single- and dual-tone generation (500 mV into 50 Ω), they can be used to generate frequency-swept signals with user-defined sweep rates. Also, by utilizing the four independent user-defined frequency/phase profiles associated with each synthesizer card, frequency and/or phase-modulated waveforms (FSK, PSK) can be generated and controlled by software or external hardware. Delivery is within 30 days.