QRSS
(Send slower, no really, slower)
Communicating at .8 WPM
Welcome to the slow lane of Ultra QRP
March, 2011 by Michael Seedman, AA6DY
With special thanks to Hans Summers, G0UPL
QRSS – The basic idea

The slower you send, the less information you’re transmitting, the less bandwidth you
need.

The less bandwidth you need, the better the SNR.

A good way to think of this - as you minimize the bandwidth at your receiver, the less
noise makes it through along with the signal of interest.

The result of this is increasing the distance you can communicate with a given amount of
power.

We all know that it takes less power to communicate in CW that in SSB. Take this a step
further and it makes sense that by using slower CW, it would take less power to
communicate with 1 second dots, or 3 second dots, or 10 second dots…

So milliwatts sent with 3 second dots and 9 second dashes can be heard around the
world – even with simple antennas. Think about this – milliwatts traveling around the
world!

In the world of QRSS, one watt of power would be considered extreme QRO!
How does it work?

Shannon’s Law – Considering all possible multi-level and multi-phase encoding techniques, the
Shannon–Hartley theorem states the channel capacity , meaning the theoretical tightest upper bound
on the information rate (excluding error correcting codes of clean (or arbitrarily low bit error rate) data
that can be sent with a given average signal power S through an analog communication channel
subject to additive white Gaussian noise of power N, is:

C is the channel capacity in BPS:

B is the bandwidth of the channel in Hz (passband bandwidth in case of a modulated signal;

S is the total received signal power over the bandwidth (in case of a modulated signal, often denoted
C, i.e. modulated carrier, measured in watts or volt^2.

N is the total noise or interference power over the bandwidth, measured in watt or volt2; and

S/N is the signal to noise ration (SNR) or the carrier to noise ration (CNR of the communication signal
to the Gaussian noise interference expressed as a linear power ratio (not as log db)
Theoretical improvements in
SNR when slowing speed
CW Speed
Bandwidth
SNR
improvement
Equivalent
Power
SSB
2.4 kHz
-24dB
1200 Watts
12 WPM CW
10 Hz
0dB
5 Watts
8 WPM CW
6.67 Hz
+1.8dB
3.3 Watts
4 WPM CW
3.33 Hz
+4.8dB
1.3 Watts
QRSS 1s/dit
1 Hz
+10dB
500 milliwatts
QRSS 3s/dit
.33 Hz
+14.8dB
133 milliwatts
QRSS 10s/dit
.1 Hz
+20dB
50 milliwatts
*Relative to 12 WPM CW (0dB)
Most QRSS activity is beacon
operation – know as MEPT
 MEPT stands for “Manned Experimental Propagation
Transmitters”
 Sending “599 IL AA6DY K” would take about 7 minutes. The
other side of the Q would take another 7 minutes or so,
making the entire QSO about 14 minutes long. So, we don’t
really do too much of this.
 Although there are people that have ‘true’ QSO’s, much of
the QRSS operation is as a beacon.
 All of my QRSS operation has been on 10.140000Mhz to
10.140100Mhz (100 Hz wide band) using 7 Hz frequency
shift keying
How do you QSL?
 A QSL in QRSS land is a screen shot of my signal in
some far away land.
The Receiver
 Any receiver with a 1Hz filter will work. The problem is that
receivers with 1Hz filters are hard to come by.
 So, we use a computer with some spectrum analysis
software. The output of the receiver is fed to the input of the
sound card. The computer does FFT’s on the signal (many
times too faint to hear with your ears)
 There are quite a few capable software packages available.
The one I’ve used is called Argo. Simple and it works.
 Argo accumulates the signal strength in sub-Hz buckets,
displaying it on the screen as the tape slides sideways.
CW is one mode, but there
are others
Plain old CW is the classic QRSS
mode, but there are others:
A. Slow CW – actually ON OFF keying
of one frequency.
B. Slow Hellschreiber – shift carrier to
generate the pattern
C. FSK-CW – CW encoded with two
frequencies about 6 or 7 Hz apart
D. Soundcard Modes – sent as SSB
signals – reverse of a Fourier
Transform
E. Pattern
F. Pattern – Easy to generate pattern.
Easy to spot, but no ID
G. Shows a ghost of the image due to
propagation
H. Notice drift and the signal bouncing
off something above.
The QRSS Transmitter

They’re typically simple home built “handful of parts” transmitters that generate 500
milliwatts or less, and can transmit two tones around 10.140 MHz – 7Hz apart.

Most QRSS transmitters are crystal controlled, and the small frequency shift is controlled
by using a varactor diode – in fact, a reverse biased LED makes a fine varactor diode.

Drift is a big deal. Crystals aren’t exactly ‘rocks’ as we know them. Temperature can
make crystals drive a few tens of hertz, which shows up in the receivers display. Many
builders put their transmitter in some kind of insulated container to keep the drift down.

Even Crystals ‘Chirp’ (although not much). At 1Hz, it can be clearly seen on the display.

The only input to the transmitter is a single bit. Transmit the low frequency, or transmit
the high frequency.

Where am I transmitting? Even a crystal can be off by more than the 100 Hz band where
people are watching. An accurate frequency counter is pretty helpful.
My First QRSS Transmitter
QRSS Transmitter Rev 1.0
I’ve built three QRSS transmitters. My first one, using a 2N5109 in the
PA, puts out about 500 milliwatts.
Here’s the signal from QRSS
Rev 1.0
P = E^2/R
10.85V p-p
X .5
= 5.4V p-p
X .707
= 3.8V rms
Squared = 14.7
Divide by 50
= 290 mW
Arduino as the Controller
 I used an Arduino as a controller for the QRSS
transmitter. If you’ve not heard of it, or played with one,
go get one. There are libraries for just about
everything. You can go to Sparkfun.com and purchase
the board for about $30. You can download the
environment free at arduino.cc.
Arduino Shields as QRSS
Transmitters
 An Arduino shield is a daughter board that fits on the
Arduino computing platform. There are lots of
prototype shields available. I used one from Sparkfun
to build Rev 2.0. Same circuit, different form factor.
My Latest QRSS Transmitter
 Arduino + DDS + Amplifier + Filter = fully
programmable QRSS Transmitter.
 I use an Arduino to speak I2C to the direct digital
synthesis (DDS) board built for a different project to
generate a square wave at the right frequency.
 The DDS square wave feeds to a schmitt trigger, and
into 4 small 2N7000 FETs.
 The voltage for the PA is controlled by an LM317
adjustable voltage regulator.
QRSS Rev 3.0
Arduino Code for Rev 3.0
 Although there are a ‘few’ lines supporting the DDS and
communications to the DDS, here’s the core of the
Arduino Code:
QSL from ON5SL in Belgium
What’s next?
I’m planning to put Rev 4 in a
new enclosure
And, while I’m at it, I was
thinking I could stretch the
bounds of QRSS
 10,860 Miles/Watt x 1500 Watts = 16,290,000 Miles
and still be under legal limit.
So, I’m going to add some
power
Introducing the new
Alpha 9590
Capable of communicating 16,290,000 miles!
Questions about
QRSS
-or
Alpha Amplifiers?