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40M WSPR Without Tears)

Raspberry Pi WSPR Without Tears (WWoT) TX Shield 40 Meters (Assembled)

Nowadays, one of the most impressive QRP modes is Joe Taylor, K1JT's WSPR (pronounced "whisper") mode. WSPR stands for "Weak Signal Propagation Reporter." Programs written for WSPR mode are designed for sending and receiving low-power transmissions to test propagation paths on the MF, HF and recently, UHF bands. The process is similar to a beacon. Users with Internet access can watch results in real time at wsprnet.org.

WSPR Without Tears is Bruce Raymond, ND8I's project to simplify the process of getting an actual transmitter up and running so you can enjoy working with WSPR and avoid dealing with the headaches associated with building a working system. What makes it really interesting is that WSPR is optimized for operating at very low power. The WWoT board puts out a whopping 200 mW which is capable of reaching impressive distances even with a bad antenna (see the map above for typical response using an-end fed dipole in an attic).

The WWoT board (or shield as referred by the community today) is an inexpensive way of turning a Raspberry Pi (Pi) single-board computer into a WSPR transmitter.

Our approach uses a Raspberry Pi computer ($35) to generate WSPR transmissions. Our board plugs into a Raspberry Pi and amplifies and filters the output (the Raspberry Pi output is a very low power square wave that would be illegal to transmit due to its harmonic content). The Raspberry Pi generates the WSPR signal in software and utilizes timing data from the Internet to calibrate its internal clock and transmit frequency, so you don't have to do it.

So join the group of Whispering Raspberries on 40 meters by ordering a TAPR 40M-WSPR-Pi today.

Pablo, WA6RSV, alerted us to the fact that not everyone realizes what a Raspberry Pi is. He said, "One week ago I thought a Raspberry Pi was a dessert! (I like apple pie!). Nobody explained to me that it is a normal computer just like your Mac or PC." It comes without a monitor, mouse or keyboard (you don't need them for this application). You program a microSD card (from a file listed below on this webpage), plug it into the Pi and you have a powerful single board computer. The microSD card contains the operating system (linux) and all of the software.

NOTE:"WSPR Without Tears" kit does not include the Raspberry Pi, power supply, microSD card or antenna.

Ordering Information

The price for the 40M WWoT is:

  • $ 29 USD

(Place Web Order)

A note regarding email addresses: When checking out please use an email address other than @earthlink.net, @hotmail.com, @live.com, @msn.com, @outlook.com. For some reason these domains reject email from tapr.org

Shipping and Handling

Shipping and Handling within the US will be by USPS Priority Mail.

International shipping costs are calculated as closely as possible. If the actual cost exceeds the estimate by more than $10.00, TAPR will contact you to get approval for the additional funds. TAPR uses insured Priority Mail International, unless the purchaser requires something else.


40M WSPR Without Tears Installation and Operation
TAPR WSPR Executables
40M WSPR SD Card Image (large file, 564M)
Win32DiskImager download

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