It turns out that the ability to send messages using very low power is related to the bandwidth of the signal. Bandwidth is a function of speed of sending so to decrease the bandwidth of your transmissions you can slow the sending speed way down. For an example if a "dit" in Morse takes 6 seconds to send an "H" , - - - -, would take 24 seconds just for one letter plus the time for the spaces between the elements. A message consisting of a 5 digit callsign and a 6 digit maidenhead location may take up to 5 - 6 minutes to send. So, remembering that a slow speed transmission requires less bandwidth, we realize that slow messages like this can be be sent using very low power transmitters. It is not unusual for a transmitter to have under 200 mW of power when using this mode. 100 mW is about 20 dbm while 23 dbm is about 200 mW of RF power. Many QRSS transmitters operate within that range and some have ventured even lower.
QRSS signals can be detected by computers and displayed visually using some clever software. The displays are captured by grabber receivers usually at 10 or 20 minute intervals and are sent to a server on the internet that displays the screenshot for anyone who is interested to see. Owners of the small transmitters use these server sites to confirm distance and direction that their signals have travelled. The transmitted messages usually contain information specific to the owner like calllsign and location. They also show the time and location of the reception and usually the site has thumbnails of the latest 10 or so captures so the viewer can call up previous periods other than the latest one.
Screenshot of QRSS signals on 30 meter band.
This all sounds pretty involved and possibly expensive but neither is true. A small transmitter built from a kit, a battery or good, clean power supply, and a wire antenna cut to the desired frequency is just about all that an operator needs to start sending QRSS signals. QRP (low power) operators are familiar with kits that can be assembled in a few hours and the frequencies that are recognized as QRSS hang outs. The bandwidth of these areas is usually very small but 30 meters uses 10.139.750 to 10.140.100 MHz so the band is pretty wide. Other bands usually have a chosen frequency +/- 100 Hz. So, it is a good thing that QRSS transmissions are very narrow and take up very little space.
When the QRSS bug bites a ham operator can do little to resist. The idea that a few mW of power can travel huge distances when propagation conditions are good is interesting to many and QRSS is a good way to experience and learn about these facets of ham radio. Also, building a simple kit and digesting the material that accompanies it will contribute to a ham's knowledge of how radios work including filtering of signals, power amplification and antenna tuning. The kits usually are microprocessor based and a program is "burned" into the memory by the kit maker. However, there usually is the capability to change the program and add or subtract any features that the users requires. Doing this can increase one's knowledge of how these little intergrated circuits are programmed and illustrate the capabilities they have.
Ultimate 3S Transmitter with GPS Option
Much like WSPR, QRSS can also be used as a tool. Ham operators like to experiment with things like antennas and since most bands have a QRSS section they can test the design and build using the transmitter. If you have cut a wire antenna for a certain frequency and you find that your meager transmission is heard 1,000 miles away that is a good indication that you have it right. Also, you can compare different types of antennas. If you have a dipole for one frequency and a EFHW for the same band you can compare their ability to be heard and see which one performs better. WSPR has been a boon to weak signal experimentation and QRSS can only complement these efforts.
U3S in various stages of completion.
Is QRSS used for rag chews or DXing? No, these types of operating require more power, possibly SSB modes and a wider bandwidth. QRSS, it seems, lends itself to experimentation and owner designed and built equipment. If that is part of your ham radio interests you should take a look at the resource list below and consider QRSS.
Resource List
Kits:
QRP Labs: https://www.qrp-labs.com/. A definite leader in small kit design. Made in Eastern Europe and China the kits have been the standard for years now. Delivery can take a few weeks but it is worth the wait.
Zach Tek: https://www.zachtek.com/. This small Swedish company designs and builts kits for WSPR and also some test equipment like signal generators and frequency standards. They can't be beat for quality and customer service.
Web Sites:
David Hassall, Wa5DJJ: http://www.zianet.com/dhassall/. A retired engineer living in southern New Mexico, David has built and maintains a "Super Grabber" facility that monitors QRSS transmissions and sends them to a server site where transmitter owners can check their propagation into that area of the world. You can read about David's journey into the QRSS area on his website and you can see examples of received signals here: https://www.qsl.net/wa5djj/.
QRSS Plus: https://swharden.com/qrss/plus/. Scott Harden, AJ4VD and Andy, G0FTD maintain a website that at any time may include representations of 65 -80 receivers of QRSS signals. Owners of the receivers submit the data to the site at predetermined intervals which are pretty timely so a transmitter owner can verify his signal soon after transmission. They have 148 stations that submit data but not all are active all of the time. In addition to the signal reports this site includes loads of information about QRSS and the hams who are involved in the low power sport.
QRSS And You, KA7OEI: http://www.ka7oei.com/qrss1.html This great site is packed with information about low power operations. It includes the software packages that are commonly used for receiving and decoding QRSS transmissions.
QRSS Knights: https://groups.io/g/qrssknights/messages. A great forum and gathering place for those who build and operate the stations involved in QRSS. It is the first place to stop by and get basic information and advice with troubleshooting and antenna construction. The "Files" section even contains the latest firmware for QRP Labs products.
There are other sites that contain valuable insights to QRSS and we will add them to this listing if we think they contain different and important information. Remember that GOOGLE is our friend. Until then, get a kit, build a single frequency wire antenna and go for it.
