--- In [email protected], "mail_adnan85" <[EMAIL PROTECTED]> wrote: > > I am planning to do my final year project on SDR. What i will be doing > is that i will make a simple Rf front-end and then demonstrate the SDR > concept by making two softwares, > 1-for FM reception > 2-for AM reception > > most of the people online and on this group talk of expensive kits > and all. I just wanted to ask you guys to help me with this and tell > me that can i do this project by the use of a DSP (alone no the > whole kit) and an analog to digital converter. I dont want to use > the sound card though. Help me out. I am kinda new. >
Hello ???? (usually messages are signed at least with the first name...) if you do not want to use the sound card, you must find another way to input your data into the PC, at a speed compatible with the bandwidth you want to be able to display in your SDR program. There are not too many alternatives : USB or IEEE1394. This latter is more complicated, hardware-wise, so let's suppose you will use USB. The steps you will have to do in hardware are : - Lowpass the RF signal to keep Nyquist happy. - Digitize the RF signal. Here you could, for the sake of your final year project, limit yourself let's say to the MW band. This will allow you to use an inexpensive ADC chip (the AD7760 comes to mind). - Now you have to do a digital down conversion to the final data rate you will send via the USB port to your software. Here the AD6620 could come of help. Or you can program an FPGA, if you so prefer. In the process of downconverting, of course you will have to generate the quadrature components I and Q - And finally you have to implement the USB interfacing. There are many chips for this on the market, albeit in this moment I can't suggest one off my mind. Software-wise, you will have to get data from the USB port, display the spectrum and/or a waterfall, bring to baseband the spectrum portion that contains your wanted signal, and apply the customary algorithms for demodulating (AM or FM) it. Things would be much easier if you would relax your requirement of not using the sound card. Then you could completely skip the hardware part by using one the inexpensive (about 15 USD) Softrock kits, and concentrate yourself exclusively on the software, which, BTW, would be simpler, not having to deal with the USB port. Just my 2 Eurocents. 73 Alberto I2PHD
