Jean-Claude:
You are correct, the mere use of a CPU or FPGA in a radio does not automatically make the device a SDR. I think the key is in understanding that if the RF signal processing functions following the A/D (i.e. decimation, filtering, demodulation etc. ...) are performed in a programmable/configurable device such as a CPU or a FPGA then you have the basis for a SDR. If the FPGA or CPU performs only some ancillary tasks such as audio filtering (even IF filtering), signal generation by way of DDS, display functions, encoder interface etc. .... Then the mere inclusion of a CPU or a FPGA to perform these tasks does not create a true SDR. In my mind, a SDR has some sort of A/D at the front end (could be a sound card) which feeds the main digital signal processing chain ( down conversion, demodulation etc.). The signal processing chain may be realized as code running in a PC, on a DSP chip or a FPGA configured to perform the required functions. If the signal processing functions are accomplished by analog means you probably don't have a SDR (unless you are using one of those software configurable analog processing chips that came out a few years ago,( but that is a stretch). -Ray WB6TPU >Right. Can a radio with DSP be called a SDR? I have a FT-897, it has >an audio DSP with autonotch, noise reduction, different filters and >could be called a SDR, but a very primitive one. Myself I would not >call it a SDR. The fact I can control it by software to tune, change >band, mode ... does not make it a SDR either. IC-746 and up, Ten-Tec >radio are SDRs. For Ten-Tec you don't even have to send it back to >upgrade the firmware. >> >> 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. >It all depends on what the FPGA does. A rig with microprocessors to >control the display, read the different buttons, read the VFO encoder >is not a SDR, but there is software in there. The same for a FPGA, it >all depends on what it does. For example if you implement a DDS in the >FPGA it does not make the rig a SDR. You can even have a FPGA >reconfigurable on the fly while using it but it won't necessary be a SDR. >You should give an example of what you intend to implement with a FPGA. >Jean-Claude PJ2BVU [Non-text portions of this message have been removed] ------------------------ Yahoo! Groups Sponsor --------------------~--> Everything you need is one click away. Make Yahoo! your home page now. http://us.click.yahoo.com/AHchtC/4FxNAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
