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I have to write a thesis about digital communications, and I don't want to write something stupid in it. I also wrote that "most of the digital modulations and signal processing nowadays are done via software". So, are these sentences true? Thanks a lot

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    \$\begingroup\$ I suggest you read a lot more on Google Scholar before you write unless that's into a search engine ;) \$\endgroup\$ Commented Dec 9, 2020 at 4:07
  • \$\begingroup\$ Name a platform that does complex digital anything that doesn't run on software. There's not many. Maybe only one: an FPGA. Meaning that doing something on an FPGA doesn't count as doing something in software. \$\endgroup\$
    – DKNguyen
    Commented Dec 9, 2020 at 4:39
  • \$\begingroup\$ In practice "Software Defined Radio" tends to loosely mean "DSP Radio" regardless if that's done in a fixed operation numerical processor, a flexible one like an FPGA, a programmable DSP, or a programmable general purpose processor. But to say that most digital modulation is done by "software" seems false, at least in terms of "stored program microcomputer" type software. \$\endgroup\$ Commented Dec 9, 2020 at 4:54

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It is true, that "FPGAs and DSPs are widely used for modulation and demodulation of signals in communications". That means, that the data link level in a canonical OSI model is implemented purely in hardware or with a strong hardware support. The reason for this is that modern high-speed communications require the processing speed, that a pure software implementation can not support.

Here you have to take into account, that, backed up by wikipedia, "a digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing". That means that a computation-intensive operations are performed with the help of specialized hardware as a part of a DSP (mainly, hardware multiplication).

An obvious example is GbE, where you have to transmit 1 billion bits per second. And even for that, modern FPGAs include dedicated hardware modules called transceivers (an example for Intel).

In a simpler cases (i.e. slower interfaces), the hardware implementation of a low-level modulation-demodulation is still much preferred. The reason for that is that to keep the link up you will need to serve it constantly, which can potentially occupy the most of the processor clocks, when implemented as a software.

It follows, that the statement "most of the digital modulations and signal processing nowadays are done via software" can be considered false.

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