On 11/21/2010 2:41 PM, Andy Talbot wrote:
There are plenty of receiver packages for Softrock.
clones and similar - now how about more SDR transmitter
software.
Giuliano I0CG and myself presented a working prototype of such a
project at the Castelfeder (near Bozen, North-East Italy)
meeting, last October. The PDF of my presentation is here :
http://www.i0cg.com/presentazione_i2phd.pdf
Unfortunately it is in Italian, but with some fantasy and guesswork
maybe it can be understood.
Giuliano is the author of the hardware project, while I wrote the
DSP software for the dsPIC.
Synthetically, the audio signal coming from the microphone is
digitized by the on-board ADC converter of a dsPIC chip at a
sampling
rate of 15501 Hz, then upsampled to 248,016 Hz, then sent through an
SPI interface to an AD-9957 device, which is dynamically programmed
to provide an SSB output that can range continuously from about zero
up to more than 100 MHz (the final sampling frequency is 250 MHz).
It was tested on the air in SSB QSOs with the US on the 20m band,
and received unsolicited comments about the very good quality
of the modulation.
Some more info on the page of Giuliano :
http://www.i0cg.com/ad9957_dds.htm
73 Alberto I2PHD
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