Cecil,
I agree with you 100%. The concept of a "Software Defined Radio" means just that. The function of the radio is defined by software. SDR does not restrict what sort of hardware the operative software operates on. A CPU (optimized for DSP or not) may execute instructions that define how the radio signal is processed (demodulated, filtered, decimated or whatever). By the same token, a FPGA may be configured (utilizing Verilog or other language) in such a manner that the FPGA also processes a digitized radio signal. The processing may include those sorts of processes that a dedicated CPU may perform albeit usually much more efficiently and at higher speeds. Then there is the concept of a soft CPU that is defined within a FPGA. That CPU could be of a CISC or RISC architecture and could execute essentially the same programs an equivalent stand-alone processor could while the remainder of the FPGA is configured to perform some other dedicated tasks. If a radio's functionality is defined by software it is a SDR with no distinction being made whether the hardware that performs the signal processing is a general purpose CPU, a CPU optimized for DSP functions or a FPGA configured to perform certain signal tasks. I get the impression the original poster is confusing a "software controlled radio" with a "software defined radio". There is indeed a world of difference between those two. A "software controlled radio" may be a conventional receiver constructed with analog parts that is controlled in the sense that some CPU commands the selection of filter bandwidths, the selection of oscillator frequencies, the selection of gain settings or whatever. They key concept is that the RF signal processing in this case is by means of conventional analog approaches and the CPU only controls certain settings of the hardware. This is in contrast to a SDR where the software is the radio. (change the software and change the signal processing). 73 Ray WB6TPU Disclaimer: yes I work for Xilinx, a major FPGA provider, but that doesn't have any effect on my previous statements. ________________________________ KD5NWA wrote: >My answer is very short. >Words have meaning. >Software >Defined >Radio >Software defines how the radio functions. It's not a CPU Defined >Radio or a Program Running Defined Radio. There are people that argue >that a DSP is not a computer, but they are plain wrong. >Verilog and VHDL are programming languages that can run on your PC or >define how a FPGA functions. If the FPGA controls the radio, your >Verilog software is defining how your radio behaves hence SDR. >But so be it, don't put FPGA's in your SDR radio, I will. At 07:45 AM 6/14/2006, you wrote: >>I have listed where I have got it and where anybody can get it from, >>read it and understand what SDR is. >> >>Why do you think it is restrictive? >> >>SDR is an evolution of the traditional concept of a radio. >>Therefore we have to make some distinctions to come to a more >>detailed understanding of what it is. >> >>For a long time we had analogic radio circuitry only. >>Then some parts have been digitalised as e.g. the VFO with the >>advent of PLL and its programmable divider stages, the >>electrooptical tuning knob etc.. >>Note, having something digital in a electronic circuit doesn't mean >>to have software running! >> >>Next it has been introduced the microcontroller to control display >>circuitry, to electronically switch of various functions (already >>made of analogic circuits) as mode, PTT, tune and some sort of >>telecontrol through an interface port (often a RS-232). >> >>At this stage of the radio evolution, SDR is not involved, yet, due >>to the fact there is still no software signal processing but >>(tele)control of the radio's hardware parts only. >> >>The successive step relates to the first DSP applications on >>processing to filter the audio signals coming from the BF stages of a RTX. >> >>This can be considered the first phase of Software Defined Radio >>because *software processes*, and not simply digital circuits >>technology!, substitutes a part of the radio circuit. >> >>The further step, and second SDR implementation phase, has been made >>by the introduction of DSP into the IF stages due to availability of >>more powerful DSP cores. >> >>I'll underline that remote as local control of circuits has nothing >>to do with SDR either if it is performed by a PC or by local >>processors in the RXT box! >> >>SDR is the technology of elaborating the to be received signals >>through software running on one or more microprocessing units (it is >>unimportant if it resides on the PC or on a DSP in the radio box). >> >>As I've stated in my precedent e-mails FPGAs are reconfigurable >>hardware circuits, not software processing units! For this reason >>FPGA cannot be considered part of an SDR. >>They are *hardware substituting some other hardware* and convenient >>in a context of a reconfigurable hardware radio. >>The fact they are reconfigured (reprogrammed) using some software on >>a PC doesn't mean that FPGAs process radio related signals by running software. >> >>In other words, local or remote radio control is not SDR. >>SDR is treating, converting, modifying a received signal by the use >>of a software program instead of traditional electronic circuitry, >>nothing else. >> >>If this concepts, in your opinion, aren't still addressing the >>points then I apology for this and invite you to take a view to the >>rich documentation I have mentioned before. >> >>vy 73s de Andreas Troschka - ik2wqi >> >[EMAIL PROTECTED] <mailto:kd5nwa%40cox.net> wrote: >> > You missed my point, where did you get your definition of a SDR radio, >> > it seems awfully restrictive. >> > >> > A PC, A DSP, and a FPGA are all controlled by "Software" that defines >> > what they do, so they are all "Software Defined Radios" >> > [Non-text portions of this message have been removed] ------------------------ Yahoo! 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