Farhan Shahid wrote: > [snip] > I want to make this into a transmitter as well. My questions are: > > 1) Which modulation scheme should i use?
I think that SSB would be adequate. Better yet, you could show the flexibility of the SDR approach by making the modulation scheme chengeable with just a nmenu choice. > 2) What will the range be(i dont mind if its not far though, anything > from 5 to 10 meters of ground distance is sufficent) Then you don't need more than 100mW, or maybe even less, easily obtainable with a general puprpose transistor used as final amplifier, like the 2N2222A, or the 2N3906. > 3) What modifications will i have to make in the software, hardware? This depends on how you have structured your present software. Basically (copying from a my past posting on this group), what you need is an NCO (Numerically Controlled Oscillator), which generates an audio frequency (e.g. 15 kHz) as an analytic signal, i.e. with the two I and Q components. This signal is fed to a software mixer (nothing more than a multiplication of complex numbers) together with the audio samples from the digitization of the microphone signal. The two I/Q output signals are then converted to analog form by the sound card DAC. From this point hardware will carry on, and an upconversion to the operating frequency must be done using either a QSD mixer, or a more conventional type (in this case it must be a double mixer, for the image cancelling function, which the QSD gives natively). > 4) How do i know which channels i am sending the signal on? This depends on the final step outlined above, i.e. the conversion done in hardware to the final frequency. > 5) What sort of Antennas and RF end be needed at both ends? Given the modest distance you want to cover, a simple string of wire will do on HF, and also the RF frontend doesn't need to be much sophisticated. > 6) Any websites/links that could help me acheive this? If you do a search with Google for "Software Defined Radio" you will find a lot of information. A good point to start is to give a look at how the transmitting part has been implemented inthe SDR-1000 project http://www.flex-radio.com/download_files/index.htm 73 Alberto I2PHD ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/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/
