Topband: Performance of Softrock V6 on 160m

[Steve Ireland]

G'day Bill

You may like to pass this information along to those on the topband 
reflector who are interested in trying SoftRock V6 hardware for 
software defined weak signal reception with the Rocky software.

I am pleased to say the V6 looks about the best of the SoftRocks so 
far on the topband.  A SR V6 prototype (built by its designer Tony 
Parks, KB9YIG) was recently put through my friend VK6APH's lab and 
found to have a MDS of -125 dBm (0.12uV), measured using an M-Audio 
D44, with a noise floor of -126dBm.

Unfortunately, I forgot to test dynamic range on the V6 (!) but the 
earlier V4 to which it is fairly similar overloaded at about -17dBm, 
using a M-Audio Delta 44 soundcard.

The strong signal handling of the SoftRocks tends to be limited by 
the need to have quite a high level of gain after the sampling 
detector-type mixer, in order that the SoftRocks can work with a wide 
range of soundcards of differing gains.

The M-Audio Delta 44 has quite a lot of gain compared to an on-board 
soundcard and from memory, I am pretty sure it was the soundcard that 
was actually overloading, not the SoftRock's mixer, when the testing was done.

Vy 73

Steve, VK6VZ