Receiving QRSS.

(within the H.F. amateur bands.)

Sample QRSS image.


Introduction

What do I need to receive QRSS?

Choosing a receiver.

Antennas for QRSS reception.

Software for receiving QRSS.

Where to look for QRSS.

What to look for.

Some QRSS captures/images.

When to look.

A QRSS sound sample.

Closing comments.
Introduction.
This is a brief introduction to receiving QRSS signals within the H.F. amateur bands based on my own experiences. The following text assumes the reader is already familiar with the theory of QRSS. If this is not the case then please have a look at What is QRSS? and the links contained within that page. After reading the theory and explanation of QRSS operation the following text should make more sense.



What do I need to receive QRSS?
Essentially four items are required for the successful reception of QRSS signals.

1) A suitable radio receiver.
2) A computer (P.C.) fitted with a sound card and capable of accepting audio signals from the receiver.
3) Suitable software to process the receivers audio and display the results on the P.C.s monitor.
4) Some knowledge of where to look in order to have a good chance of finding QRSS signals.



Choosing a receiver.
Many of the requirements for a QRSS receiver are much the same as for any other amateur bands receiver, good selectivity, good frequency stability and reasonable sensitivity consistent with good strong signal handling capability. However, what may prove to be a satisfactory receiver for more general amateur or short wave listener activities may prove to be very poor for QRSS applications. It is equally true that a simple home-brew receiver which may not be very good for general amateur use can prove highly successful for QRSS applications.

For best results when receiving QRSS signals perhaps the most important requirement is that the receiver should have good short/long term frequency stability. But what happens if the frequency stability is not as good as it should be? To answer that question let us assume for a moment that you have set-up your P.C. with suitable software (more on that later) and connected the P.C. sound-card I/P to your receiver. Let us further assume you have tuned your receiver to the correct frequency and that you have found some QRSS signals to display. If your receiver does not have satisfactory frequency stability you may find the results very unsatisfactory. I can demonstrate the results of poor frequency stability using screen captures taken from  Argo software running on my own P.C. Below are two images showing the result of poor LO/BFO stability within a receiver.
 
RX with poor frequency stability-1         RX with poor frequency stability-2

Notice how the QRSS signal appears to be going "downhill" in the above images due to the local oscillator and/or the BFO/carrier insertion oscillator frequency "drifting" with time. The image (above left) shows the level of drift soon after the receiver had been switched-on, the second image (above right) shows how the drift begins to reduce (less sloping of the signal) as the receivers internal temperature stabilizes. So, the gradient of the "slope" is directly related to the amount of LO/BFO drift in the receiver. The LO/BFO frequency drift causes the spectrum of audio frequencies presented to the P.C. to change in frequency with the result that the processed signals displayed on the P.C. monitor also appear to change in frequency over time. If the receiver LO/BFO drift becomes excessive then the signal will eventually drift outside of the display window requiring re-tuning of the receiver or adjustment of the display window to compensate for the error. Also in the first image (above left) notice the sudden jump in frequency (arrowed) which causes some distortion of the signals image. So, good frequency stability is a prime requirement for good QRSS reception. 

It is worth pointing out that while the receiver used in the examples above clearly gives less than optimum results for QRSS applications it has always performed well in general SWL and amateur service, I have listened to long CW/SSB contacts many times with little or no re-tuning required. The point is that it would be wrong to assume that a receiver which gives satisfactory results in general amateur service will give equally satisfactory results when used for QRSS.

Short term L.O./B.F.O. stability. 
Aside from the requirement for long term frequency stability there it is also desirable that the receiver exhibits good short term frequency stability. Poor short term frequency stability or "jitter" in the LO/BFO of the receiver causes the displayed signals to exhibit "wobbly" or "staggered" lines, this can be seen in the images above in which the receiver has both poor short and long term frequency stability. Possible causes of poor short term stability include poor mechanical construction or excessive phase noise in the LO/BFO due to poor design. The "jitter" in the receiver LO/BFO causes the audio output spectrum from the receiver to be equally jittery such that the audio signals presented to the PC sound card are jumping around in frequency. Following processing by the software this results in a "staggered" or distorted display on the PC monitor. In extreme cases of LO/BFO phase noise/jitter the signal can appear to be spread over a wider spectrum of frequencies than it actually is. This "spreading" of the signal also makes weak signal recovery less successful.

For comparison purposes I have included a screen capture (below) of a signal received using an old Yaesu FT707 receiver which incorporates a VFO Because of the less than optimal stability of the VFO the resulting image of the QRSS signal displays the same "downhill" slope as the previous examples. What makes this example different is that the old FT707 has a much better VFO/LO/BFO performance than the receiver in the previous examples exhibiting much lower phase noise/jitter. The result is that while the displayed signal is sloping downhill due to the poor long term frequency stability the signal image is free of the "stagger" which was visible in the previous examples.

    FT707 example.

One of the simplest ways to improve the long term frequency stability of a receiver is to ensure good thermal stability of all the oscillators used in the receiver, this can be accomplished with the use of an "oven" to regulate and maintain the temperature of the oscillator circuits or frequency determining components within the oscillators. More on the subject of temperature stabilization of oscillators can be found here.  Crystal ovens for QRSS applications.

If the receiver you choose for QRSS reception does not have a temperature stabilized L.O./B.F.O. it may still give acceptable results if it is left to "warm-up" long enough such that the receivers internal temperature can stabilize. The Target HF3S I used for some of the example images shown above has acceptable frequency stability for QRSS reception if it is left to warm-up for about six hours! I found it also helps to keep the shack door closed as well in order to keep the room temperature stable.

AGC Problems. 
Generally AGC is a bad thing when it comes to QRSS reception, the reason for this is that quite frequently the wanted signal (QRSS) is very weak and probably just above the noise floor of the system. The receiver will (even in its narrow bandwidth setting) have an I.F./A.F. bandwidth of perhaps a few hundred Hz with the result that stronger signals within the I.F./A.F. pass band may cause the AGC to reduce the receiver gain. This reduction in receiver gain not only reduces the strength of the unwanted signal but also the strength of all signals within the pass band, this in turn can have an adverse effect on the displayed QRSS signal. The effect of the stronger unwanted signal which caused the AGC action on the weaker QRSS signal is sometimes called AGC "pumping" and has the effect of amplitude modulating the weaker signal. Since the amplitude of a QRSS signal is normally displayed as a change of  display intensity by the software the net result is that lighter and darker areas appear on the displayed images which correspond to the AGC action on the stronger signal. This effect can be seen in the two images shown below where the FSK-CW signal "fades" due to the action of the AGC, notice the Morse character "F" (left hand image below) has faded and part of the "M" pattern has also faded due to AGC action. The QRM signal used for the examples below was a locally generated CW signal with the "key down" every few seconds.

      AGC "pumping" 1          AGC "pumping" 2

Another undesirable "feature" of some receivers is the effect of distortion (I.M.D.) within the audio stages of the receiver. In normal amateur radio service the audio stages can have several percent of distortion and the effects often go unnoticed since they have little or no effect on the intelligibility of narrow bandwidth telephony (speech) or telegraphy (CW) but with QRSS those unwanted IMD products can manifest themselves as unwanted "ghost" signals when viewed on the PC running QRSS software. The image on the right (above) shows the effect of AGC "pumping" and also shows some of the IMD products caused by the strong signal used to induce the AGC action, the unwanted "ghost" signals are shown arrowed.

So, for best results when receiving QRSS use a narrow I.F. bandwidth setting and make sure the AGC is turned off. Reduced BW will help to reduce the effects off unwanted signals and improve QRSS reception. Since the QRSS sub-bands are generally no more than 100 Hz wide it is quite acceptable to use a BW of say 300 to 500 Hz as might be used in CW operation. If your chosen receiver does not have such narrow bandwidth settings you may still be able to obtain acceptable results with QRSS though much depends on the level of band activity and just how strong the QRM signals are.

So, to sum up, here are some of the desirable qualities for a good QRSS receiver which are additional to the requirements for regular amateur radio receivers.

1) Exceptionally good long term frequency stability.

2) Good short term frequency stability (No "jitter" in the LO/BFO etc)

3) Good sensitivity consistent with good dynamic range.

4) No AGC or AGC switched-off.

5) Low IMD in the audio stages.

6) A choice of I.F. bandwidths with at least one CW bandwidth setting of  500 Hz or less.

If after reading these notes you decide that nothing you currently have in your shack is suitable for QRSS reception then you may wish to consider home brewing a receiver. As indicated earlier, successful receivers for QRSS reception need not be complex and can be built using readily available components.
An example of a simple home brew direct conversion receiver for 30 Mtr QRSS reception can be found here.

A simple 30 Mtr direct conversion receiver for QRSS reception.

Here are two example images of several QRSS signals obtained using the simple (but very stable) direct conversion receiver mentioned above.

   A good QRSS rx example 1          DC RX sample image.

Antennas for QRSS reception.
In many cases the choice of antenna that will be used is dictated by an individuals QTH, personal preference, local restrictions or the space available for antennas. My preference for any receiving antenna is to have some form of "balanced" antenna such as a dipole. At my QTH local noise/QRM is a dominant feature on all of the H.F. bands up to about 22 MHz and I have found that the use of a balanced receiving antenna helps to reduce the local QRM considerably. If you happen to live in an electrically "quiet" QTH then an antenna which "captures" as much of the signal as possible may be your preference, you may even prefer to use a vertical antenna with a view to picking up more of the low angle radiation.

If you are new to QRSS and currently have no antenna for the 30 Mtr band then I would recommend a trusty dipole as a good starting point. Mount the dipole as high as you can and if possible keep it as far away from any known local QRM sources such as TV sets, Computers etc. Use a balanced feeder all the way back to the shack or a balun at the dipole center with a good quality coax feeder back to the shack. A very interesting design for a compact 30 Mtr dipole appears on the web pages of I2NDT (Claudio), this antenna is suitable for both RX and TX purposes. A link to his page appears below.

Interesting Dipole Antenna design by Claudio (I2NDT) 

If you are troubled by local noise then you could try a small active loop antenna. I use an active loop antenna here and have found it to be very successful at defeating local QRM. Several choices are possible, a passive resonant loop antenna which has a high "Q" and narrow BW, this helps to reduce the level out-of-band signals and helps to prevent IMD in the front end of the receiver which can arise from powerful SW BC stations. Even low levels of IMD can cause "ghost" signals to appear which can be mistaken for QRSS carriers. Another form of loop antenna is the compact "active loop" antenna, the "active" part is an RF pre-amplifier which is used to compensate for the small dimensions of the receiving loop. A compact active loop can also be made resonant and because of its small physical size it needs less space than other forms of antenna. A variation on the resonant active loop is the broad-band active loop, this is also a "balanced" antenna and therefore resistant to local QRM but has the added advantage of being able to cover the entire L.F./H.F. spectrum. This is good if you have limited space for antennas and wish to pursue QRSS and general SWL activities. This has been the case here at M0AYF where a broad-band active loop has been used for a couple of years now with good results. The possible disadvantage of the broad band active loop is that it risks IMD in the front end of the receiver due to the high strength of signals which are far removed from the frequency of interest. IMD has not been a problem here at M0AYF and if your chosen receiver has good IMD performance then the broad band loop may be a choice worth consideration. The physical location of the loop (be it active/passive/resonant or non-resonant) should be chosen with the same considerations as for the dipole mentioned earlier. If you are interested in experimenting with a "wide bandwidth active loop antenna" then follow the link below.

A Wide Bandwidth Active Loop Receiving Antenna.

Software for receiving QRSS.
Several pieces of software exist which are suitable for viewing QRSS signals but since this web page is intended for those with no prior experience of QRSS I will describe the use of just one such software package.
 
If you have never looked for QRSS signals before and you are completely new to QRSS then my advice would be to begin by downloading a copy of Argo
which can be downloaded from the web pages of I2PHD using the link below.

Link to Argo web site.

First read the instructions for that software to become familiar with its operation. Argo is well written and very easy to use, connection to the radio receiver is via the P.C. sound cards "Line I/P" the same as many of the other sound card based software packages currently available. For more information and advice on connecting your P.C. to your receiver have a look at these web pages.

http://www.w5bbr.com/soundbd.html

http://www.qsl.net/wm2u/interface.html

http://www.arrl.org/news/features/1999/0701/2/?nc=1

http://www.ik3qar.it/rtty/1/

http://www.waypoint.com/users/~discobay/Sound_Card_Presentation.htm

Having connected your radio receiver to your P.C.s sound card you should now check that the P.C. is getting the audio signal from your receiver. This can be done in several ways but perhaps the easiest method is to "loop through" the sound card and check you can hear the sound from your radio receiver also coming out of your P.C.'s speakers. The sound should be set to a reasonable level such that it is loud enough to be heard but not distorted. Having confirmed that the receivers sound is reaching the P.C. correctly you can now attempt to tune in a test signal with which to check the operation of Argo Look for a weak broadcast station carrier or other stable signal that is weak but constant and set the receiver so you get an audio "beat note" with a pitch of around 800 Hz. Now launch Argo and using Argo's "Full Band View" you should see a vertical white line (or thick white bar) running vertically down the screen at around 800 Hz. You should find that by adjusting the clarifier control the pitch of the "beat note" changes and the position of the white line/bar also changes. This will indicate that the receiver/P.C. sound card connections are correct. If you have problems then re-check the connections to your receiver/P.C. sound card and/or consult the instruction manuals for your P.C./Sound card and receiver.

Where to look for QRSS.
If you don't know exactly where to look for QRSS signals then its like "looking for a needle in a haystack" so if your new to QRSS I would suggest looking around 10.140 MHz but before you do so please check the calibration of your receiver. The indicated frequency on the receivers frequency display is no proof that it is the true frequency being received. An error of only 100 Hz could mean the difference between successful reception of QRSS or not seeing anything at all. An error of  +/- 100 Hz may be fully acceptable for CW/SSB working but for QRSS reception an error of  +/- 10 Hz would be more acceptable. To check your receivers frequency display accuracy you can use one of the methods listed below for calibration.

1) One of the many frequency standard broadcasts (MSF on 60 kHz, WWV on 10 MHz etc)
2) A GPS disciplined crystal oscillator.
3) Use an existing QRSS signal of known accuracy as a comparative reference.
4) Take the horizontal synchronizing pulses from a TV broadcast and use them to phase lock a crystal reference oscillator.
5) Use one of the "Propagation Beacons" for frequency calibration. (Beware of this method!)

 1) One of the many frequency standard broadcasts (MSF on 60 kHz or WWV on 10 MHz)
The short list of options above are intended only as a guide, you may prefer to use a different option. My own current preference is to use a harmonic of a 10 kHz square wave signal derived from a divided down 6 MHz crystal oscillator which is phase locked to MSF on 60 kHz. The design I use is based on a design built by Andy (G4OEP) which can be found here. MSF "Off-Air" Standard.  My version of the MSF phase locked reference can be found here.

An MSF Locked Frequency Standard for QRSS Calibration.

2) A GPS disciplined crystal oscillator.
The second option above is becoming increasingly popular due to the falling cost and availability of GPS systems. Many of the units available provide an O/P which is phase locked to the atomic clocks used in the GPS satellites. More information on this option can be found here.
 
A GPS Disciplined Oscillator.

3) Use an existing QRSS signal of known accuracy as a comparative reference.
Of the four possible methods listed above number three is perhaps the simplest but you have to be sure that the QRSS signal you choose has a known frequency and is very stable.

4) Take the horizontal synchronizing pulses from a TV broadcast and use them to phase lock a crystal reference oscillator.
The line timebase synchronizing pulses for analog television broadcasting are generally derived from a very stable source so by phase locking a crystal oscillator to these pulses it is possible to make a very accurate and stable reference source for frequency calibration. The signal can be taken from the composite video O/P of a SCART connector or the phono (RCA socket) composite video O/P found on the back of some TV sets. A word of caution, it seems that with the move towards digital broadcasting you may find that the composite video O/P of a digital TV receiver/decoder has some "irregularities" in the recovered synchronizing pulses which make it unsuitable for frequency calibration purposes. You would have to check the technical details of the chosen broadcaster before building a unit based on the use of synchronizing pulses. Here in the UK we still have analog TV broadcasting and the BBC transmissions use synchronizing pulses which are locked to an atomic standard so they would be entirely suitable as a reference for calibration purposes. However, over the next few years the move towards "all digital" TV means that synchronizing pulses derived from an all digital system may not be suitable for calibration purposes.

5) Use of "Propagation Beacons" for frequency calibration (Beware of this method!).
Before we go any further, a cautionary note. In my own early experiments with QRSS viewing I had been using the IK3NWX propagation beacon on 10.1418 MHz as a frequency calibration source. The receiver I was using at the time was a Target HF3S, this is the same receiver used for the examples of a poor frequency stability receiver shown above. Because of the wide I.F. B.W. of the receiver (around 4 kHz or more) I was able to see the IK3NWX beacon using Argo in "Full BW" mode while simultaneously being able to see the QRSS sub-band. By adjusting the receiver BFO such that IK3NWX appeared at around 2.5 kHz in Argo I would then know to look for QRSS between 700 and 800 Hz which equates to 10.140000 - 10.140100 MHz. This worked quite well but on some occasions it was evident that I was "missing" part of the QRSS band. It turned out that it was the IK3NWX beacon which had "drifted" very slightly in frequency. So, if you choose a propagation beacon for frequency calibration then first check up on its frequency stability. It is only fair to point out that the IK3NWX propagation beacon does not drift very much and by most standards actually has excellent frequency stability. The very slight changes in frequency of the beacon only become apparent when compared to other more stable frequency sources. If you are in the EU then using the IK3NWX propagation beacon would help to put you in the right "ball park" for QRSS viewing in the absence of one of the other frequency calibration methods listed above.  I should also like to add that the IK3NWX propagation beacon is an excellent indication of propagation conditions and at this location (IO93oj) it has proved to be a very accurate indicator for the possibility of receiving EU QRSS signals at any given time. I have found that if IK3NWX is weak but detectable in Argo then it is fair to assume that other EU QRSS signals will be detectable here in the UK.

Probably 90% of the QRSS activity takes place in the 30 Mtr amateur band between 10.140000 and 10.140100 MHz (100 Hz window), this is not an "official" sub-band, it simply happens to be where most of the QRSS activity takes place. The propagation conditions on this band are such that contacts from just a few hundred kilometers to thousands of kilometers are possible even with modest antennas and low power levels. Activity also takes place (to a lesser extent) in the 40, 80 and 160 Mtr bands. The exact frequencies are often linked to readily available crystals, for example QRSS signals in the 80 Mtr band are often located around 3.580 MHz and in the 40 Mtr band 7 MHz crystals are often used so the signal can be located within the first 100 Hz or so just above 7 MHz. There has also been activity in Italy within the 10 Mtr band using very low power (a few mW) from "canned" crystal oscillator modules. There are no fixed rules on the exact frequency or bands used for QRSS but given the nature of QRSS it makes sense to co-ordinate activity as much as possible with other enthusiasts in order to have the best chance of receiving other peoples signals or having your own signals received by others. To that end there is a very active mailing list on the Internet dedicated to QRSS activity which can be found here.

Details for subscribing to the QRSS mailing list can be found here.

In addition to the QRSS mailing list there is also a QRSS "clip-board" which details some (though not all) of the current QRSS activity at any given time, both of these resources can be very useful in identifying QRSS signals. The QRSS clip-board can be found here.
A number of QRSS enthusiasts have HF receivers connected to a PC uploading real-time screen captures of qrss signals to the web. Since both the number and status of these on-line resources may vary IK0VVE has created a "HF Aggregator page" which brings together as many of the on-line grabbers as possible onto a single page. Because of the unpredictable nature of radio propagation we do not promise you will see QRSS signals every time you view the grabbers so its worth checking back from time-to-time.

Link to IK0VVE's "HF Aggregator" page.
More QRSS related resources can be found on my links page here.
What to look for.
As already indicated the greatest QRSS activity will be found to be in the 30 Mtr band between 10.140000 to 10.140100 MHz. First tune your receiver to 10.140 MHz (USB). Using a stable test carrier or signal generator set to 10.140 MHz  and loosely coupled to the receiver antenna adjust the BFO/Clarifier control to give a "beat note" of around 800 Hz.. The choice of 800 Hz for the beat note is not critical, its just a fair bet that 800 Hz will be well within the audio bandwidth limits of the receiver/sound card. If the beat note is set to low (say 250 Hz) it could be attenuated slightly by the receivers audio filtering, if the beat note is set to high (say 3000 Hz) then it will fall outside of Argo's working window. At this point it is also a good idea to check Argo's settings are the same as those in the image below. For general QRSS viewing these settings have been found to be optimal for most conditions and are recommended as a good starting point.

Argo settings.

Now using Argo's "Full Band View" look for a continuous vertical line between 800 and 900 Hz, this is your test signal. The appearance of a vertical line between 800 and 900 Hz assumes you have set your receiver to 10.140 MHz, checked the receivers frequency calibration and also set the receivers audio beat note to 800 Hz. Now position the mouse pointer on the vertical line and "click" the left mouse button, this should then change Argo's display to a horizontally scrolling window just over 100 Hz wide. After a few minutes you should see a horizontal white line appear on the display which corresponds to your test signal. How straight this line appears depends on the stability of your receiver/test signal. Now switch off the test signal and go back to Argo's "Full Band View" and look for similar (though possibly weaker) vertical lines and again position the mouse pointer on one of the vertical lines and "click" the left mouse button to change Argo's display to the horizontally scrolling window. After a few minutes you should have enough of the signal to look at to decide if it is a QRSS signal or not.  Do not be discouraged if you don't see QRSS signals on your first attempts, a great deal depends on propagation, current levels of QRSS activity, QRM levels etc.
 
Some examples of QRSS signals are shown below, they will give you an idea of the sort of signals you might expect to see and the various modes that are sometimes used. Various patterns are popular in QRSS operation because they "stand out" better under poor conditions and the patterns used are also a good way to "personalize" a QRSS transmission, a sort of QRSS signature.

Click on any of the thumbnails below to see a higher resolution image.

FSK-CW   Slant-CW   MT-Hell   DSB-Hell

Multimode-QRSS   M0AYF and G0UPL Patterns.   I0CG pattern-2

The "Skater" (DL6NL)   QRSS slow ramp.   IZ2EEQ SIN wave pattern.
Another "Hell" capture thumbnail.A WSPR ("Whisper") capture thumbnail.


WSPR (pronounced "whisper")
The WSPR (pronounced "whisper") capture shown above is a recent development in the world of QRSS which uses software running on a PC to generate a number of audio tones with frequency spacing of only a few Hertz. These tones can be fed into the microphone input of an SSB transmitter in order to transmit a very narrow bandwidth (less than 10 Hz) coded signal. While the coded signals can be viewed using Argo (or similar software) the signals are intended for decoding using the WSPR software. The coding of the signals conveys information such as call sign and signal-to-noise ratio.

The software was written by Joe Taylor (K1JT) who also wrote the very successful WSJT software used for meteor scatter experiments. At the time of writing (April 2008) the software is still developing with many innovations and improvements still to come. A full description of this mode is not possible because of the speed with which new developments to the software keep appearing so for the latest information please go to Joe Taylor's WSPR download and information page.

Link to WSPR download and information page.

Most WSPR activity within the 30 Mtr band is (by voluntary agreement) located in the 100 Hz segment directly above the10.140000 to 10.140100 MHz QRSS sub-band. So for WSPR activity look around 10.1400100 to 10.140200 MHz though (at the time of writing) a number of stations are operating outside of these limits due to the "congestion" on the band from other WSPR operators, such is the popularity of this mode. A number of operators are also using equipment with poor stability (by QRSS standards) so they tend to "drift" outside of the agreed limits. Also (at the time of writing) many of the WSPR operators are using far to much power, WSPR is a very sensitive mode requiring very low power (500 mW is normally enough) but many new WSPR operators who are also new to QRSS are running several Watts! To be fair this can be due to the use of commercial equipment which is not capable of power reduction below a few Watts but the result of using to much power is to "swamp" the screens of QRSS viewers.

 
When to look.
A good time to look is at the week end when activity is normally at its highest. There is sometimes activity during the week to but if you are new to QRSS and looking for the first time then the week end offers the greatest possibility of success. The time to look depends on the the time of year, propagation conditions etc so its a good idea to learn about the propagation characteristics of the 30 Mtr band. I also recommend checking some of the on-line resources mentioned towards the end of the "Where to look for QRSS" section so you will know what the level of activity is likely to be.

QRM from contest stations (both CW and RTTY) can be a problem so try to avoid those week ends when the contests are running. Though we share the 30 Mtr band with other radio amateurs the QRM is normally not to bad with the exception of contest week ends already mentioned. It is not unusual for the odd CW or RTTY QSO to appear right in the middle of the QRSS segment but generally (with the exception of contests) the operators finish the QSO within minutes and move on. The slow nature of QRSS means that over a period of a few hours several QRSS signals may be copied with only sporadic interruptions by other band users. Most of the time the other band users are unaware of the QRSS signals because they are often sub-audible.

My own success at receiving QRSS was very slow to start with, this was partly due to my lack of experience with this mode and partly due to the use of a receiver that had excessive frequency drift. It took me several weeks before I saw my first confirmed QRSS signals. Following my first successfully received QRSS signals the search process became much quicker and easier, within a few more days finding and capturing QRSS images became almost routine. 


A QRSS sound sample.
If you find you are having difficulty in finding or tuning into QRSS signals then perhaps the following 6 minute QRSS sound sample might help. Because of local QRM at the time the recording was made you may find that locating the QRSS signals is "challenging" but this recording serves as a good example of what to expect in a "noisy" environment and should provide a good signal to explore the features of Argo with. This is a large "Zipped" Windows "wav" format file (4.57 M/bytes) which you can download, un-zip and then replay on your own P.C.

When you have successfully downloaded (using the link below) and unzipped the file the next step is to select Argo's "Setup" menu, then go into the "Select Input" menu followed by "Choose real time input" sub-menu. Now select the "What U hear" option and make sure all other inputs to your P.C. sound card are disconnected. If you now play the sound file you should be able to hear the sound playing in the speakers of your P.C. while at the same time you should be able to view the results in Argo as if it was "live" audio from your receiver. Listening to the sound file you will hear a faint "buzzing" sound which is the QRM from local T.V.'s and P.C.'s etc. You will also hear some static from distant thunderstorms and if you have exceptional hearing you may be able to hear the faint whistle of the QRSS signals at around 1660 Hz, I cannot hear anything but QRM and static but after processing with Argo the QRSS signals will be easily detected and perfectly visible. To download the "Zipped" QRSS sound sample click on the link below.

"Zipped" QRSS audio sample for downloading. Warning, large file (4.57 M/Bytes)

The sound sample was recorded on Monday the 23rd of October 2006 at around 11:00 UTC using my QRSS 30 Mtr direct conversion receiver.
Because of the direct conversion receivers local oscillator offset the QRSS band appears centered around 1660 Hz. If you select  Argo's "Full Band View" and look in the area of 1660 Hz you will see a couple of unbroken vertical lines, they are the QRSS signals. You will also see many more broken vertical lines which are of much greater signal strength from around 400 to 1900 Hz. They are caused by local TV QRM and my own P.C. monitors harmonics. Now position the mouse pointer at a point corresponding to 1660 Hz and "click" the left mouse button, this should then change Argo's display to a horizontally scrolling window just over 100 Hz wide. You should now have a horizontal scrolling display which shows the QRSS band between 10.140000 to 10.140100 MHz just as I viewed it here at the time/date shown above. If you want the horizontal display to show the correct frequency then enter the following frequency offset (see Argo's instructions) of 10138385 into Argo after which the horizontal window will then show the correct 30 Mtr band frequency plus or minus any small tolerance in the frequency of your sound cards clock oscillator. You should be able to resolve two FSK CW QRSS signals (plus QRM from TV/Computer etc), the FSK CW signal uppermost (about 10.140080 MHz) is that of G4OEP, notice the "spreading" of the signal probably due to multiple signals with some Doppler shift. For me (here in the UK) this was a "short skip" signal and happens quite frequently. The lower signal (about 10.140027 MHz) is that of DL6NL which is also an FSK CW signal and remained visible for most of that day.

I played the audio clip a few hours after the recording was made to check it was valid and also took a screen capture of the recorded signals using Argo,s screen capture feature. The captured image is shown below and this is what you should see if you replay the audio clip as described above.
Sound sample capture.


 Closing comments.
The information presented here is by no means exhaustive or complete but hopefully it will give you some idea of the requirements for successful QRSS reception. Based on my own experience it is possible to receive QRSS signals with very modest equipment and worry about refinements later. For example, a receiver which has a modest amount of frequency drift will often still produce good results if the user is willing to accept that it may need constant re-tuning over a period of time. Such a receiver only becomes problematic when you want to leave the system "capturing" images automatically over extended periods. In such a case of "unmanned" operation it may be found that the signals drift outside of the capture window and with no one around to correct the tuning some of the QRSS signals may be missed.

I hope this has been helpful but if you still have unanswered questions then please feel free to contact me and I will be happy to try and answer any questions relating to QRSS. Alternatively have a look at the "links" section of this web site and also take a look at some of the other QRSS "Knights" web sites, this may help you to see the subject of QRSS from a different perspective. If you decide that QRSS is for you then "welcome aboard" and good luck with any QRSS projects you may undertake.



Well, that’s about it, thank you for reading this and please send any questions, comments or "heckles" etc to the e-mail address linked below.

e-mail QSL

73,s

Des (M0AYF)