In this tutorial you will use [[RF.Spice]]'s black-box virtual blocks to model a Quadrature Amplitude Modulation (QAM) communication system and construct a pair of transmitter and receiver circuits. Then you will use a long lossy transmission line as the channel to connect the transmitter and receiver circuits. You will simulate the transmission of a binary data packet through this communication link.
== Overview of the COMM FMCW Radar System Architecture==
Quadrature Amplitude Modulation (QAM) is In an FMCW radar system, a digital modulation scheme that chirp signal is similar in nature to launched into the analog AMfree space using a transmit antenna. A binary data sequence chirp signal is converted to an FM-modulated signal of a pulse train that serves as the baseband known stable frequency whose instantaneous frequency varies linearly over a fixed period of time by a modulating signal of the communications system. The baseband transmitted signal is split into two equal parts hits at the target and reflect back to a receive antenna. The frequency difference between the two parts are mixed with synchronous cosine receive signal and sine versions of the carrier frequency f<sub>c</sub>. The up-converted signals are then summed together transmit signal increases with opposite signs delay, and the resulting QAM signal delay is sent linear proportional to the channel. The figure below shows range, that is the basic simplified architecture of distance between the QAM communications system. There can be additional blocks including gain stages radar and signal shaping filters, which have been omitted here for the sake of simplicitytarget. Â On the receiver side, the received QAM signal Echoes from the channel is split into two equal parts and the two parts target are then mixed with synchronous cosine and sine versions of the carrier frequency f<sub>c</sub>. The down-converted signals are then summed together with opposite signs and the resulting transmitted signal goes through to produce a peak detector. The output analog beat signal then passes through a comparator to recover which will give the transmitted binary sequencedistance of the target after demodulation.
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