Software defined DDS controlled HF radio project

The SDR Transceiver Version 2 is basically just progress in the vein of my SDR TRX 1st version. The biggest change in SDR2 is that it will be working at intermediate frequency of around 8.4 MHz.

Most important changes are:

SDR working with intermediate frequency of around 8.4 MHz and thus only one calibration values needed for QSD and QSE, no imbalances caused from chanching the operation frequency (as with direct sampling QSD and QSE).

Better DDS or Si570 DSPLL

Bandpass filters that are specific for HAM bands, no general coverage RX anymore.

The Minimization of the amount of relays used in the whole transceiver, QSK.

Update 11.2.2010

Lots of stuff has happened since the last update. Have been so busy with the SDR2 that haven't had time to update these pages, hi.

The QSD+QSE and front end boards are finished. After small tweaking (adjusting the biases of the pre- and post amplifier) I was able to get quite good noise figure and premilinary IP3 values (estimated by defining the 1 dB comp point), both seem to match the calculated values.

Next mission is to design tight band pass filters. The goal is to get 100 dB image rejection, which will be really hard task, but you gotta set some goals!

My digicam battery seems always to be low when I need it. Pictures will come really soon.

Update 18.5.2009

The design is finnished: The intermediate frequency is 8.4 MHz. The mixer before QSD is switch mode mixer, which has theoretical IP3 close to +35 dBm and insertion loss of 6 dB, thus giving very good dynamic range. At least block schematic will appear soon. The board also has option for roofing -kind of filter in the front of QSD which has BW of only around 300kHz. I will test and see if this improves the performance of the receiver.

Update 10.9.2008

Project started. Desinging features mentioned in the "General Description".