The ni_proc VI that we used in Exercises 2 and 3 provides the basic functionality we need for receiving AM signals, but the limitations of the MFJ preselector or the Elenco radio as a "front end" effectively limit our choice of received signals to the AM braodcast band.
For this week's lab, we will use a Ten-Tec RX320D receiver as our front end. This is a computer controlled "black-box" radio which uses a PC based GUI rather than physical knobs and buttons. It combines an analog triple-conversion superhet architecture with a DSP chip demodulator. Since it brings out the final IF signal on a rear-panel connector, it makes an ideal companion for a Labview based IF processor/demodulator.
The figure below is a simplified block diagram of the RX320 receiver. Image rejection and bandlimiting are provided by analog filtering, so we can simply digitize the 12 kHz out signal and begin processing. For additional information on the RX320 hardware, refer to the Schematics and the Programming Manual.