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Table of Contents

Introduction................................................................................................................................................1
Approach....................................................................................................................................................2
Raspberry Pi...............................................................................................................................................3
What you'll need to complete the assembly...............................................................................................3
Programming an SD Card..........................................................................................................................4
Setup......................................................................................................................................................4
Program SD Card..................................................................................................................................4
Install SD Card into Pi...........................................................................................................................5
Assemble WWoT and Pi............................................................................................................................6
Setup and Adjustment................................................................................................................................7
What You Need......................................................................................................................................7
Getting SSID and Passkey.....................................................................................................................8
Initial Setup...........................................................................................................................................8
Locate the Pi IP Address........................................................................................................................8
Setting WSPR Configuration..............................................................................................................10
Restart Pi.............................................................................................................................................11
Measure RF Output.............................................................................................................................11
IP Addresses........................................................................................................................................12
WWoT Schematic....................................................................................................................................12
Troubleshooting - It Doesn't Work ..........................................................................................................14
Appendix 1 - Communicating With the Pi over SSH..............................................................................16
Appendix 2 - Postprocessing Data..........................................................................................................17
WSPRnet Map.....................................................................................................................................17
Downloading Data...............................................................................................................................19
WSPR Data Filter................................................................................................................................19

Introduction

Thank you for purchasing the WSPR Without Tears transmitter (WWoT). We hope you'll be pleased
with it. WWoT is our attempt to put together a WSPR transmitter transmitter that avoids (hopefully)
most of the problems associated with building a fairly complicated digital mode transmitter. All of the
information, data and files are accessible through the TAPR website:
tapr.org/kits_WsprWithoutTears
WSPR stands for Weak Signal Propagation Reporter Network. It's a digital mode used by hams. The
process is similar to a beacon. WSPR is a wonderful communication mode created by Joe Taylor
(K1JT). WWoT is our attempt at simplifying 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.
TAPR (c) 2018-2019 "WSPR Without Tears"
WSPR Without Tears
1 Of 20
Version 2.1 05/20/2019

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Summary of Contents for TAPR WSPR Without Tears

  • Page 1: Table Of Contents

    WSPR Data Filter..........................19 Introduction Thank you for purchasing the WSPR Without Tears transmitter (WWoT). We hope you’ll be pleased with it. WWoT is our attempt to put together a WSPR transmitter transmitter that avoids (hopefully) most of the problems associated with building a fairly complicated digital mode transmitter. All of the information, data and files are accessible through the TAPR website: tapr.org/kits_WsprWithoutTears...
  • Page 2: Approach

    There are two problems with using the Pi for WSPR. First, the output signal is a square wave with harmonics from here out to next Tuesday. A low pass filter is necessary to keep other hams and the TAPR (c) 2018-2019 “WSPR Without Tears” 2 Of 20...
  • Page 3: Raspberry Pi

    The operating system (Linux) and all of the software are stored on a micro SD card. The SD card is plugged into the Pi. Set it and forget it. You need a card reader (<$10) and software (from the TAPR website) and an SD card to do this.
  • Page 4: Programming An Sd Card

    2. SD Card reader/writer. We've got a Targus Micro SD/T-F. It doesn't really matter what card reader/writer you use. It connects your SD card to a USB port. 1. Win32DiskImager – It's a freebee. Download it from: tapr.org/kits_WsprWithoutTears or sourceforge.net/projects/win32diskimager/.
  • Page 5: Install Sd Card Into Pi

    Installed in Pi). The SD card sorta slides in up side down. On Pi 2.0 it ratchets in (pops in then out a little and sorta locks in place). On Pi 3.0 there's a friction fit, so there's no locking. Figure Figure 2: Inserting SD Card into Pi TAPR (c) 2018-2019 “WSPR Without Tears” 5 Of 20 Version 2.1 05/20/2019...
  • Page 6: Assemble Wwot And Pi

    Attach the WWoT board to the Pi. The BNC connector is on the opposite side from the Pi USB connectors( Figure 4: WWoT and Pi Assembly). The micro USB power connector is coming out of the TAPR (c) 2018-2019 “WSPR Without Tears” 6 Of 20...
  • Page 7: Setup And Adjustment

    4. SSID and passkey for your router (see below if you don't have these) 5. PC connected to your network 6. Optional: USB WiFi adapter for Pi 2.0 (Pi 3.0 has WiFi built in) TAPR (c) 2018-2019 “WSPR Without Tears” 7 Of 20 Version 2.1 05/20/2019...
  • Page 8: Getting Ssid And Passkey

    Locate the Pi IP Address 1. Working from your PC, download WSPR Executables (zip file) from the web site (tapr.org/kits_WsprWithoutTears), unzip the zip file, and extract the program WSPR_Locate.exe to a suitable work area. 2. Execute WSPR_Locate.exe. The program will take about five minutes to execute and will (hopefully) give you the IP address of the Pi.
  • Page 9 After setting the WiFi portion of the WSPR configuration (see Figure 7: WSPR Configuration Screen), WSPR_Locater will display inet addr for eth0 if the Ethernet cable is still connected and inet addr for wlan0, the WiFi connection. TAPR (c) 2018-2019 “WSPR Without Tears” 9 Of 20 Version 2.1 05/20/2019...
  • Page 10: Setting Wspr Configuration

    WSPR Without Tears Setting WSPR Configuration Figure 7: WSPR Configuration Screen TAPR (c) 2018-2019 “WSPR Without Tears” 10 Of 20 Version 2.1 05/20/2019...
  • Page 11: Restart Pi

    RF Level and Gnd. This should be in the range of 3-5 volts, indicating the WSPR transmitter is generating full power. TAPR (c) 2018-2019 “WSPR Without Tears” 11 Of 20 Version 2.1...
  • Page 12: Ip Addresses

    Ethernet cable if you’re planning on using WiFi. WWoT Schematic The WWoT schematic is shown in Figure 8: WWoT Schematic. Congratulations! Connect an antenna and you're done. TAPR (c) 2018-2019 “WSPR Without Tears” 12 Of 20 Version 2.1 05/20/2019...
  • Page 13 WSPR Without Tears Figure 8: WWoT Schematic TAPR (c) 2018-2019 “WSPR Without Tears” 13 Of 20 Version 2.1 05/20/2019...
  • Page 14: Troubleshooting - It Doesn't Work

    Keep in mind that we're using a cheap DVM, you're probably using a cheap DVM, and component tolerances could be all over the place. This means that if your readings are within, say 10%-20% of ours that they're probably okay. TAPR (c) 2018-2019 “WSPR Without Tears” 14 Of 20 Version 2.1...
  • Page 15 If you find voltages that differ significantly from what's listed on the schematic, start by looking for bad solder joints. If that fails, let us know because we're probably looking at a bad component, which we will be happy to replace. TAPR (c) 2018-2019 “WSPR Without Tears” 15 Of 20 Version 2.1...
  • Page 16: Appendix 1 - Communicating With The Pi Over Ssh

    2. Get the IP address of the Pi from WSPR_Locater. 3. Run the KiTTY and enter the IP address for the Pi. This will open a command window. 4. Username: pi Password: wspr TAPR (c) 2018-2019 “WSPR Without Tears” 16 Of 20 Version 2.1 05/20/2019...
  • Page 17: Appendix 2 - Postprocessing Data

    Time Period to 24 hours, click on the Day/Night overlay checkbox if you want to see it and then click on the Update button. You can pan and zoom to see how far your signal has gotten. TAPR (c) 2018-2019 “WSPR Without Tears” 17 Of 20 Version 2.1...
  • Page 18 Database in the upper left and change Band to the appropriate band (30m, 40m, etc) and add your callsign. Click the Update button. Figure 11: WSPRnet Database TAPR (c) 2018-2019 “WSPR Without Tears” 18 Of 20 Version 2.1...
  • Page 19: Downloading Data

    (part of the executables file). The program removes everything but your contacts from the downloaded data making it a much more reasonably-sized file. Figure 12: WSPR Data Filter TAPR (c) 2018-2019 “WSPR Without Tears” 19 Of 20 Version 2.1...
  • Page 20 1. Download a month's worth of data from WSPRnet.org. 2. Unzip the file (these are big files – it will take some time). 3. Download Run WSPR_Data_Filter (download from tapr.org/kits_WsprWithoutTears, click on WSPR Executables and extract the program from the .zip file).

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