Topband: Software defined radio receiver for 160m

[Steve Ireland]

Hi Bill

Those on the topband reflector who are interested 
in trying a cheap high-performance software 
defined radio for 160m may be interested in the following.

Kits of parts (including PCB) for the SoftRock 
Version 6 with 160m components will be available 
from Tony KB9YIG by mid-March and if anyone is 
interested, they can email Tony at 
<mailto:raparks at ctcisp.com>raparks at ctcisp.com 
.  Tony believes this is the best version so far 
for 160m operation.  The kit costs $14 US/Canada 
and $15 for DX – and contains some surface mounted device components

I have been using a Softrock Version 4.0 on 160m 
for a couple of months now, using VE3NEA’s free 
Rocky software – see 
<http://www.dxatlas.com/rocky/>http://www.dxatlas.com/rocky/ 
- and a Pentium 4 PC.  An 24-bit M-Audio D44 
soundcard is used for the analogue to digital 
conversion and provides a bandwidth of 
96KHz.  The combination of Rocky and the Softrock 
provides a highly sensitive bandscope, using a 
polyphase fast Fourier transformation algorithm 
that enables you to clearly see S2 or S3 signals 
and that you can spread across your computer 
screen, and a digital filter that is variable 
from 500 down to 60Hz by a ‘drag’ of a mouse.

The version 4 of this little SDR ‘sampler’ 
provides a dynamic range of 98dB and has replaced 
my FT1000 for searching 160m for weak 
signals.  For every four weak signals I can see 
on Rocky, I can usually only find one of them by 
careful tuning of the FT1000 (unless I cheat and 
peek at the Rocky bandscope).  The 
‘sensitivity’/ability of the Softrock to find 
weak signals on 160m is as good as my FT1000.

If you want to try SDR, these little kits are 
great fun – although a watchmaker’s 
eyeglass/magnifying glass is a useful accessory for making/checking joints.

Vy 73

Steve, VK6VZ