An Overview of WSPR and its use

I have been enjoying using an interesting low power mode called WSPR lately. WSPR stands for “Weak Signal Propagation Reporter” and it can be used in several ways.

The software was developed by Joe Taylor, K1JT, who is a Princeton University professor who has won the Nobel Prize in Physics in 1993 for discovering a new type of pulsar, which opened up ways of studying gravitational waves.

Because of Taylor’s work in Astro-physics, and his interest in ham radio, he has been personally involved in amateur radio moon bounce projects. His contribution has been the development of extremely powerful moon bounce communication programs for the amateur community, which he provides for free.

From his moon bounce software, Taylor has recently developed a group of software packages that are intended for use in amateur bands, particularly HF (though VLF, LF and VHF/UHF/SHF applications also can be used.)

You can find his free software and documentation at his website

K1JT has also developed the very popular FT-8 and JT-65 weak signal modes from his moon bounce work, and the software that supports those, and other weak signal modes (check out his very popular WSJT-X software on the same site – I will cover those modes in my next posting here.)

First, let me outline how the program works. It is a free software program that works with any SSB transceiver, a  computer (Windows or Linux or Mac OS 10.0), a computer software program that synchronizes your computer clock to an atomic clock (easy to find and almost always free – needed for accurate time synchronization with other stations), and a computer/transceiver sound card/CAT interface.

As the name implies, high power is not needed. 5 Watts or less (and we are talking really less, as in micro-watts is desirable), and a connection to the Internet.

The reason for the Internet connection lays in what makes it a unique piece of software and operating mode. It is not used for communicating in the conventional sense, but you do communicate and connect with other hams.

This information is collected and collated at When you run the software, and transmit, your information (call, frequency, location, power) is sent to the wsprnet site.

When one or more stations with the WSPR software receives your signal, with its information, that information is sent off to wsprnet as well. That information is further collated into three forms.

A map showing the location  all of the active stations around the world and whom they are connected to. (See the feature map at the top of the page for a portion of the image from that map.)

A list of all of the stations who have been using the wspr program and the band/frequency they are on.

WSPR Activity

Portion of the data base available showing wspr stations, the band that they are operating on, the frequency they are transmitting on, and their call signs

An historical summary of all of the stations you have connected to, which you can organize by various categories.

Wspr Sept 24 2017 20 m

Historic data of contacts for one or more stations, based on search criteria. In this case, it is one hour of transmitting using my transciever on 20 meters using 5 watts to a vertical antenna.  15 stations recieved the signal and reported it to, where the information is stored in thea database. The satistics show; date, time, my call, frequency, the signal to noise rating of my signal when recieved by the other station, the amount of shift in my frequency when recieved, the amount of drift in my frequency when recieved, my location (using Maidenhead grid coordinates), call sign of the station who recieved my signal, their location (using Maidenheat grid coordinates), distance of recieving station form my own in km, az – azmuth heading from my station to the recieving station. 

From this information you can measure a number of things:

  • The general propagation characteristics for a given band at a different times, from within an hour to over a period of time.
  •    The efficiency of your antenna set up on different bands vs. different conditions.
  •    The potential for other stations to hear you based on your current antenna configuration (eg is your antenna configuration favoring a particular direction [especially if you have a wire antenna rather than a beam], or are there directions that are ‘blocked’ due to structures, such has hills.)

The software can be used on any ham band, and there are now a set of unique frequencies that have been voluntarily accepted in the ham community (as the bandwidth used is very narrow.*

[* The modulation method used in WSPR uses 4FSK (frequency shift keying.) This is a binary mode, but rather than just using 2 bits (0 and 1) it uses 4 bits (00 01 10 11) as a result, 4FSK can carry double the data of 2FSK. In addition to FSK’s ability to carry data digitally, it is also very resistant to noise. Today, 4FSK is used in data modes such as PSK, as well as audio modes, such DMR.]

Set up and operation of the software is very simple. After running the software once to install it, all you need to do is put in your call sign, your location as a Maidenhead coordination number (either four or six digits) and the settings for your CAT and sound card settings.

(You should also have the atomic clock synchronization software running as well. As mentioned, it is very important for the time on your computer and those of other hams who are using the same program, to be as closely synced as possible.This is due to the way that the software sends and receives the data, as well as decodes it. Accurate data decoding is very dependent on accurate timing.)

Once that has been done, all you need to do is connect the software to your transceiver by the modem deice that you use (e.g. SoundBlaster) and set the transceiver to USB mode (used for all bands), select the proper WSPR frequency for the band you are using, and have the power at 5 watts or less.

WSPR program

The WSPR software dashboard – showing the main features

Then you just sit back and let the software do all the work. Setting the TX % will determine how often you transmit (25% is about the best. 100% means you are transmitting with only very brief gaps and no monitoring time.)

After you have transmitted a couple of times, you can go to and view your statistics (they are generated in real time.) You will also see a listing of the stations you connected to and their information on the dashboard of the wspr software (see the photo with call outs with an explanation of the information that you are seeing.)

The operation of WSPR focused completely on sending out information and receiving information, and transferring that information to the website. There is no provision for altering the information or having any kind of a QSO with it.

You could, if you wanted to, QSL to a station who has connected to you, if you feel so inclined, but at this point I do not know what the agreed upon practice is. Again, the primary purpose of the software is to measure propagation under low power conditions and to allow people to measure the performance of their equipment using low power.

However, as an adjunct of QRP, I can see some applications. For example, the new LF ham band, which has not been explored as much as it should, is restricted to one watt input power. Using WSPR to research propagation with different antenna systems is a potentially useful application of the software and mode (the software and collects data from contacts on that band.)

Do try out this mode if you are set up for digital operation as it is free and is very interesting to see the results on different bands. It is something that can be set up and left to its own as there is no need to monitor it.

The only thing that is missing in the software design is an ability to set up a schedule or a sequence of frequencies, in order to test propagation over time and band. Other than that, I have no issues.

If you have any questions, please feel free to get in touch with me.


Joe Cooper​


About VE3FMQ

Have been a licensed Canadian Amateur Radio operator for 50 years and have have Advanced and CW endorsement. I can cover all bands from 160 Meters to 70 cm. My favorite modes are FT8 and FS8Call.
This entry was posted in Digital Modes, WSPR and tagged . Bookmark the permalink.

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s