Simplest SDR

[kc2orw]

Found this one the other day figured I might fool around with this one too, just because... :)

TinySDR

http://www.qrz.lt/ly1gp/SDR/

Just for educational purposes I have been looking at the whole SDR topic working my way back from high level projects down to low level projects like TinySDR. I want to build some SDR homebrew projects as modules I can assemble together for testing purpose.

So I wonder what is the simplest vector modulation circuit that I can build is, any thoughts...

Sorry I am not experienced in vector modulators.

[kc2orw]

Sorry I am not experienced in vector modulators.
Me either Jerry but I keep researching the topic anyway. I just want to get down to the lowest level circuitry used in a number of SDR projects.

Here is a definition that I ran across:

Vector Modulation

A vector modulator implements a complex mathematical sum, multiplying two input signals with in-phase (e.g. cosine) and quadrature (e.g. sine) versions of the carrier and summing the result. If the input signals are arranged to be cos(w1t) and sin(w 1t), where w 1 is the desired frequency shift to be imposed on the carrier, then the output of the summing junction with be duly shifted by the required amount.
http://www.avren.com/Courses/TX_RX_Architectures_plain_files/image042.gif
With single chip implementations of a vector (quadrature) modulator now available (RFMD, Analog Devices, HP, Motorola, etc). this approach is gaining support, making the design of the carrier source (synthesiser) much simpler. In addition, the vector modulator is not limited to frequency modulation but can impose any complex modulation format (amplitude, frequency, phase) onto a carrier.

Oh well I will continue along

[kc2orw]

Here is a series of non SMT SDR projects I ran across.

Several variations on RX, two Xceiver circuits, and on TX all using non SMT components.

I am going to try a few of these out and probably breadboard them if it works out I may just finish them deadbug or ugly technique...
Don't feel like bothering with PCB boards and they look feasible for non PCB board construction techniques.
Oh yes the writeup is done by a non native English speaker/writer so you may need to re-read a few paragraphs. Still between circuit diagrams, block diagrams, and the text it is manageable to understand the writers information.

http://yu1lm.qrpradio.com/homebrew.htm

Have fun.