sig_proc_SigGen_SC.asciidoc

+== https://es.technikum-wien.at/openlab/openlab_wiki/wikis/home[Home] | https://es.technikum-wien.at/openlab/openlab_wiki/wikis/sig_proc_osci_SC[<Signal Processing Front-End (soundcard-Oscilloscope)] | https://es.technikum-wien.at/openlab/openlab_wiki/wikis/sig_proc_SigGen_FPGA[OSignal processing Back-End (FPGA-Signal Generator)>]
+
+Consumer sound cards are not intended to supply a lot of power. They serve as signal source
+or sink for external audio systems and operate on voltages of a few volts. Line level for consumer
+cards is defined as -10 dB at a reference voltage of 1 VRMS, which equals 447 mVpeak
+for sine waves. As manufacturers push the limits to advertise the loudness of their devices,
+many devices actually provide more, including all devices the user application was tested on.
+Measurements yielded peak voltages between 1-2Vpeak, which exceeds the nominal line level
+by far. Still, for a signal generator higher amplitudes are desirable. Therefore an analog output
+stage was developed. The output stage amplifies the signal and provides variable DC offsets.
+It is connected by a 3.5mm TRS audio jack to the sound card. This ensures a maximum of
+compatibility. A USB connector provides the necessary power. In the this diagram, the functionality
+is shown schematically. More details about individual parts can be found in the following
+sections.
+
+{empty} +
+
+image::https://es.technikum-wien.at/openlab/openlab_wiki/wikis/img/sig_proc_siggen_sc/Sig_proc_schematic.PNG[caption="Figure 3: ",title="Functional block diagram",height=250,align="center"]
+
+{empty} +
+
+Just to control a DAC, a microcontroller seems to contradict the low-cost goal, but since the here
+designed hardware is subject for later integration on a final printed circuit board (PCB) with the
+sound card oscilloscope of the OpenLab project, it is possible to share some resources. Hence
+a microcontroller, namely an ATmega16U2 from Atmel [1], could be utilized without increasing
+the final price too much.
+
+{empty} +
+
+== Bibliography +
+
+The content of his chapter is taken from the master thesis "_Development of a Sound Card Based Arbitrary Waveform Generator_" by Jakob Kriegbaum, MSc, May 2017.
+
+. ATMEL: _8-bit Microcontroller with 8/16/32K Bytes of ISP Flash and USB Controller_, 2012 
+
+{empty} +
+
+== https://es.technikum-wien.at/openlab/openlab_wiki/wikis/home[Home] | https://es.technikum-wien.at/openlab/openlab_wiki/wikis/sig_proc_osci_SC[<Signal Processing Front-End (soundcard-Oscilloscope)] | https://es.technikum-wien.at/openlab/openlab_wiki/wikis/sig_proc_SigGen_FPGA[OSignal processing Back-End (FPGA-Signal Generator)>]
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