EMRFD Message Archive 6875

Message Date From Subject
6875 2011-11-24 08:37:09 jasonb1963 Portable Software Defined Transceiver
I put together an architectural diagram of the simplest highly portable software defined transceiver I can think of that should still offer good performance. Here is the link to the document: http://dl.dropbox.com/u/17650857/Portable%20Software%20Defined%20Transceiver.pdf

Highlights are as follows:

o Single band for simplicity
o Targetting 75mA current draw at 12V for receive
o Targetting +30-37dBm of output power (Class C/E)
o Based on a 40-MIPS DSPic33 MCU
o "Pluggable" GUI -- use with an Android, iOS, or detachable
touchscreen display depending on user's preference.
o VFO to use SI-571 for excellent phase noise performance and
flexibility with tuning/modulation
o RX based on switched I/Q mixer using a high-speed bus switch
(tpd around 250 picoseconds). Should provide respectable
OIP3 performance.
o MCU-controlled AGC implemented with PGAs with 0-60dB of gain
which when combined with the 12-bit ADCs gives a theoretical
dynamic range of up to 132 dB.
o TX capable of any type of FSK or PSK modulation (but lack of
linear output capability probably limits BPSK use, although
OQPSK should work well).
o Addition of I/Q TX mixer possible but would compromise
efficiency of RF PA (can't use Class C/E) and would
complicate the design of the TX in exchange for gaining
no limits on possible digital transmit modes (practically
speaking you would add QAM and your BPSK output could be
filtered to eliminate splatter).

I'm curious to know if anyone else in the group has similar interests and would like to collaborate on this or a similar project? There are so many different aspects to this project (Android/iOS "App" development, DSP programming, circuit design, construction, etc.) that its a bit overwhelming to consider doing the entire thing on my own.

6883 2011-11-24 20:07:45 dan edwards Re: Portable Software Defined Transceiver
have you seend the 'SDR to Go'? from the AQRP guys...a 'look ma, no computer'  approach to SDR?


(scroll down...)
73, w5xz, dan

6885 2011-11-24 22:00:31 jasonb1963 Re: Portable Software Defined Transceiver
Hi Dan,

Thanks for the reference. I just downloaded their user manual. The SDR2GO looks similar to what I have in mind. The main differences are that I would like to focus on digital modes and I would like to have swappable user interfaces depending