Signal and QRSS
(A complete rebuild of
this site is well overdue! However I am not sure when I will
have the time to do that.)
NB - My former call sign (VK6DI) is
no longer assigned to me. Current operations are limited to
'receive only' as VK2DDI. My sole antenna is a PA0RDT
Mini-whip. I receive very well on all bands up to approx 10
QTH is near Berry
Mountain New South Wales (Elevation 512M ASL). QRSS and WSPR
uploads are ongoing dependant of course upon
local lightning or lack thereof.
of my receive activities can be accessed from here.
update as VK6DI (Near Perth) - April 13, 2009:
NB - All activity
from this location has now ended. With a little luck a new
site will replace this one later in the year.
Thanks go to all who have contributed to my success in receiving
milliwatt level (and less) signals, both QRSS & WSPR.
The current QRPp
DX record to this location is held by WB3ANQ.
Larry's 0.5 mW QRSS, & 1
signals have been received here many times.
Several other stations are not too far behind Larry's record.
Their sub-20 mW DX signals have been
decoded here using the WSPR mode on 30M.
are due to Alan
VK2ZAY who has
generously provided both disk space & bandwidth to archive my
old VK6DI web pages for future visitors.
LF-NDB / SDR-IQ file archive available
Guide to 30M QRSS reception, view or download from here.
My (West Australian)
(date sorted) as PDF
(freq sorted) as PDF
2006, 1200 hours local time: 80 Nanowatt
test as per previous details with VK6JY (see below).
(Update: 4 May 2006, signals were detected at 50 nW)
April 2006, 1450 hours local time: 200
Nanowatt tests as per previous details with VK6JY (see below).
March, 2006, 1736
hours local time: NVIS 40M QRPp tests
VK6JY produced good results at powers down to 50 uW. See
below. John is located in Albany at grid square OF84wx and is
some 383 Kms south of me. Powers below 50 uW were not
attempted due to time limitations. Clearly success
reduced power levels would have been possible.
VK6JY 50 uW
Simple low dipole antennas were used at both ends of the path.
March 17, 2006, 1000 hours local time: Further tests on 80M
VK6JY at 63 uW and 16 uW revealed results similar to previous 40M tests
a few days earlier.
VK6JY 16 uW
John's TX antenna was an 80M dipole at 8M above ground level
(AGL). My RX antenna was an 80M full wave loop at 5M AGL.
Feb 1, 2006: 30M QRSS experiments were
WB3ANQ using a
measured power output of 961 microwatts into Larry's outgoing 50
ohm coax line. (Lets call it 1 mW!) Full details of
end of the operation are available from WB3ANQ.
time Skype VoIP communications
propagation times enabled Larry and myself to accurately determine that
band conditions were favourable for an attempt to break the 1 mW
barrier into VK6 at a time near to my local sunrise. Larry's
power output was gradually reduced as conditions were seen to improve,
and eventually I was fortunate enough to capture Larry's weak 1 mW Argo
Australia. Later in the day, and near to sunset my time,
1 mW signal was also detected on the long path.
surprisingly previous 1 mW tests
with WB3ANQ had
proved unsuccessful using my low 40M dipole as a RX antenna.
The balance of the equation was tipped in our favour on this occasion,
due I believe, to the recent erection of 50 foot high 30M inverted V
dipole at my end of the path. Interestingly Larry's similar
dipole had at the time of this test been damaged by high
Larry eventually decided to switch to an alternate dipole some 20 feet
lower. Once that was done, Larry's signal appeared from out
the noise amid much rejoicing at each end.
1 mW and 1 Watt signals can
be seen as
waveforms slowly sweeping between 10140065 and 10140070 Hz in the 2
captures hereunder -
WB3ANQ at 961 uW
at 1 Watt
the lower 1 Watt
comparative image was received on my
40M dipole some weeks prior to the 1 mW test.
Due to the minimal signal strengths involved,
Larry's periodic CWID was not visible in any of the 1 mW
Clearly such minimal signals are also well below any receiver's audible
noise floor, and so cannot be detected by ear. It was
only due to Argo's effective 0.34 Hz QRSS3 bandwidth that this signal
short path #1
short path #2
short path #3
mW short path #4
mW long path #5
tests run with Larry, WB3ANQ have since yielded a weak trace at 500
An older example of the results obtainable using minimal TX power, can
be seen in the 30M QRSS long path screen capture shown below as also
received from Larry, WB3ANQ's
signal generator (QRSS3
My receiving antenna
at that time was a low 40M dipole. (Yes I do mean a 40M
Ray Experiments on 40M (VK6DI)
I2PHD / IK2CZL
(Weak signal and other Software)
link to VK6DI is
Please report any