Let's build a Compact Low Power Automated WSPR Monitoring Station (Part 2)

Image: ZS1I WSPR Monitoring Station   

Part 1 of "Let's build a Compact Low Power Automated WSPR Monitoring Station" using a Raspberry Pi Zero 2 W and RTL / SDR Receiver is available HERE.

In this part we will be looking at the complete, comprehensive operation and reference manual for "The Automated Raspberry Pi Zero 2 W WSPR Monitoring Station".  The images below depict the final fitting of all the modules together to constitute the monitoring station.  It currently monitors the 40 Meter WSPR section of the band.  However I will  revert it back to the 6-meter "Magic Band" monitor background routine once everything is working as it should.  Hopefully I can provide more information in this regard in Part 3 and also the linking of a smartphone push alert hook-up to let me know of any band activities. I will also look at how this monitor station sends spots automatically to WSPRNET and other WSPR sites once it spot stations.  In Part 4, I envisage setting up an automated Raspberry Pi Zero 2 W WSPR Monitoring Station for FT8.  More on this in the future. 

This article (Part 2) pulls together all the working commands, custom configurations, and troubleshooting steps that successfully brought my node to life.

---

📘 Raspberry Pi Zero 2 W WSPR Monitor Station Reference Manual

This station is configured as a headless background listener using a Raspberry Pi Zero 2 W, an RTL-SDR Blog V4 receiver, and the C-optimized rtlsdr-wsprd decoding engine. It continuously tracks weak signals, logs them locally, and prepares to upload spots to the global network.

---

🔌 Hardware Configuration

• Host Processor: Raspberry Pi Zero 2 W (running Debian Bookworm Lite 64-bit)

• Receiver: RTL-SDR Blog V4 (with integrated 125 MHz upconverter architecture)

• Station Parameters:

  • Callsign:  ZS1I

  • Grid Locator:  KF15bt (Mossel Bay, South Africa)

  • RF Gain Baseline:  32.8 dB

---

🛠️ Section 1: Crucial Management Commands (Start, Stop & Status)

The monitoring program runs headlessly as a Linux background service called wspr-monitor.service. You can control it completely using these standard administrative commands over SSH.

⏹️ How to STOP the Background Monitor

Run this before changing frequencies, testing antennas manually, or shutting down your Pi to ensure the software safely releases control of the RTL-SDR Blog V4 dongle:

bash

sudo systemctl stop wspr-monitor.service

▶️ How to START the Background Monitor

Run this to fire the background listener engine back up into automated listening mode:

bash

sudo systemctl start wspr-monitor.service

🔄 How to RESTART the Background Monitor

If you change a configuration or want to clear the memory hooks, cycle the engine cleanly using:

bash

sudo systemctl restart wspr-monitor.service

Use code with caution.

🔍 How to Check the LIVE Operating Status

Run this to check if the background listener is healthy, actively running, and processing data:

bash

sudo systemctl status wspr-monitor.service

Tip: If this status display opens inside a text-viewing screen, press the q key on your keyboard to exit back to the normal command prompt.

---

📄 Section 2: Viewing Your Decoded Spots & System Logs

Because the background daemon runs silently, you can use these commands to peek behind the curtain and watch what it is decoding or processing.

📻 View Live Decoded Spots (ALL_WSPR.TXT)

Every successful over-the-air decode is appended into a local text log file. Use the tail command with the -f (follow) flag to stream new spots live to your screen as they occur:

bash

tail -f /home/pi/ALL_WSPR.TXT

⏱️ View System Countdown Timers (journalctl)

If no spots are printing, you can watch the software's internal clock sync loops, hardware connections, and 2-minute slot calculations tracking live via the Linux system journal:

bash

sudo journalctl -u wspr-monitor.service -f -n 20

---

⚡ Section 3: Safe Operating System Power Management

Because the Raspberry Pi handles files continuously in the background, cutting the physical power abruptly can corrupt the MicroSD card filesystem. Always use these safe software power loops.

🔄 How to Reboot the Station Cleanly

bash

sudo reboot

🔌 How to Safely Shut Down the Station for Storage/Moving

Run this command, wait roughly 30 seconds for the tiny green LED on the Pi Zero 2 W to stop flashing and turn off completely, then unplug the micro-USB power cord safely:

bash

sudo poweroff

---

🏗️ Appendix: Original Installation & Compilation Summary

For your records, here are the step-by-step technical layers compiled onto your system image to make the RTL-SDR Blog V4 and decoder compatible:

1. Core Build Dependencies Installed:

bash

sudo apt update
sudo apt install git cmake build-essential libusb-1.0-0-dev curl autoconf 

libcurl4-openssl-dev libfftw3-dev -y

2. DVB-T TV Tuner Blockade (Blacklisting):

To ensure the Linux OS hands raw control of the RTL chip directly to the radio software instead of viewing it as a TV antenna:

bash

echo "blacklist dvb_usb_rtl2832u" | sudo tee /etc/modprobe.d/blacklist-rtl.conf

3. Official RTL-SDR Blog V4 Driver Compilation:

Compiled from source to resolve the [R82XX] PLL not locked! frequency matching errors:

bash

# Variable-safe cloning used to counter terminal truncation bugs
U_PROTO="https:"
U_DOM="github.com"
U_USER="rtlsdrblog"
U_REPO="rtl-sdr-blog"
git clone "${U_PROTO}//${U_DOM}/${V4_USER}/${V4_REPO}.git" rtlsdr-blogv4
cd rtlsdr-blogv4 && mkdir build && cd build
cmake -DINSTALL_UDEV_RULES=ON -DDETACH_KERNEL_DRIVER=ON ..
make && sudo make install && sudo ldconfig

4. WSPR Daemon Compilation:

bash

U_REPO_WSPR="rtlsdr-wsprd"
git clone "${U_PROTO}//${U_DOM}/Guenael/${U_REPO_WSPR}.git"
cd rtlsdr-wsprd
make && sudo make install

5. Automated System Service Template Location:

Saved at /etc/systemd/system/wspr-monitor.service, the configuration targets the core HF testing band:

• 40m Core Test Dial Frequency: 7.0386M

• 6m Core Propagation Monitor Frequency: 50.293M

   

Installing the Waveshare ETH/USB HUB HAT (B)  -  AI Version  

Unlike basic Ethernet extensions that communicate over slow SPI pins, the HAT (B) uses a Realtek RTL8152B controller chip. This means it functions as a high-speed USB-to-Ethernet controller coupled directly to an onboard USB Hub chip. Because it maps onto the system using standard USB protocols, the configuration strings we use must instruct the Raspberry Pi Zero 2 W's micro-USB data port to activate its OTG Host Controller Layer (dwc2). Without this specific instruction, the HAT will only draw power, leaving the Ethernet port and the 3 extra USB slots completely dead. 

🛠️ Step 1: Configure the OTG USB Host and Disable Wi-Fi 

1. SSH into your Pi Zero 2 W using your current Wi-Fi link. 

2. Open the system hardware boot configuration file: 

 bash

 sudo nano /boot/firmware/config.txt 

3. Scroll all the way down to the very bottom of the file and paste this block. It turns on the mandatory USB host tracking layer for the Waveshare hub and turns off the internal Wi-Fi/Bluetooth circuits to minimize RF noise near your receiver: 

text 

# Waveshare ETH/USB HUB HAT (B) Core USB Activation dtoverlay=dwc2,dr_mode=host

# Turn off built-in Wi-Fi and Bluetooth to lower shack RF noise 

dtoverlay=disable-wifi 

dtoverlay=disable-bt 

4. Save and exit the file (Ctrl + O, then Enter, then Ctrl + X). 

🏗️ Step 2: Physical Mounting and Pogo Pin Care 

The Waveshare HAT (B) uses spring-loaded gold pogo pins underneath to press directly against the testing pads on the bottom of your Pi Zero 2 W. This avoids needing extra connector wires, but it means physical alignment must be perfect. 

1. Shut down your Pi safely from the terminal: 

bash 

sudo poweroff 

2. Unplug the micro-USB power cord when the green LED turns completely dark. 

3. Carefully align the Pi Zero 2 W on top of the Waveshare HAT (B). Make sure the gold pogo pins sit flush against the copper contact pads on the bottom of the Pi. 

4. Tighten the included plastic standoffs and screws firmly. If the screws are loose, the pogo pins won't make a solid connection, and your Ethernet chip will lose contact. 

5. Connect your network LAN cable from your router directly into the HAT's RJ45 port. 

 6. Crucial Power Rule: Plug your micro-USB power supply cable into the port labeled USB PWR on the Waveshare HAT, rather than into the Pi Zero itself. The HAT will supply stable power up through the pins to the Pi and ensure the RTL-SDR dongle doesn't starve for current. 

🔎 Step 3: Boot Up and Track the Wired Link 

1. Plug the power supply into the wall. You will see the red PWR indicator light illuminate on the HAT. 

2. After a few seconds, the green ACT network light on the RJ45 port will begin flashing as it pulls a new IP address from your router.

3. Give it 1 minute, open your network scanner app, and search for the Pi's new wired connection profile. 

4. SSH back into your Pi using the new IP address or your local hostname:

bash

ssh pi@6m-monitor.local 

5. Run this command to check that the network traffic is routing purely through your new Realtek wired adapter interface (eth0): 

bash 

ip a 

The automated WSPR monitor (wspr-monitor.service) will fire up automatically, detect the wired connection, and continue logging the /RX spots to the local file and uploading them to WSPRnet over the network cable! 

Now that the 40 meter setup is completely dialed in, automated, and feeding the global maps under its own clean identity, you can let it run headlessly to test it's stability.  My setup has been running flawlessly!

I will now be moving onto the next part of the project in Part 3 as mentioned Supra.

Images:  Click on images for larger view.

 

# AI Contribution Acknowledgement

**Project Title:** Compact Low Power Automated WSPR Monitoring Station
**AI Tool Used:** Google Gemini (Alphabet Inc.)
**Date of Usage:** August 23, 2026


### 1. Nature of the AI Assistance
Google Gemini was utilized as a technical research and design collaborator during the initial conceptualization and planning phases of this project. Specifically, the AI assisted with:
* **System Architecture:** Brainstorming hardware component combinations optimized for low power consumption.
* **Component Selection:** Evaluating trade-offs between microcontrollers, single-board computers (SBCs), and software-defined radio (SDR) receivers.
* **Software Workflow:** Outlining the software stack required for automated signal capture, decoding, and data uploading.

### 2. Specific Prompts Utilized
The primary prompts used to guide the AI session included:
* *"What are the hardware options for building a ultra-low-power automated WSPR monitoring station?"*
* *"Compare using a Raspberry Pi Zero 2 W vs an ESP32 for decoding WSPR signals."*
* *"Outline a compact automated software workflow for a Linux-based WSPR receiver."*

### 3. Human Integration and Verification
While Google Gemini provided architectural frameworks, component suggestions, and structural outlines, all engineering decisions, physical assembly, circuit design, and final code verification were executed entirely by the human author ZS1I. The AI's outputs served strictly as a structural guide to accelerate development. 

### 4. Final Responsibility Statement
The author (ZS1I) has independently reviewed, verified, and tested all technical data, schematic choices, and software configurations suggested during the AI session. The author assumes full responsibility for the ZS1I contents, safety, regulatory compliance (amateur radio licensing), and operational outcomes of the final ZS1I monitoring station.

Lets build a Compact Low Power Automated WSPR Monitoring Station (Part 1)

Image:  Current ZS1I test setup (Click on image for larger view.) 

As mentioned before I am busy gearing up for the next 6 Meter DX Season soon to open in South Africa. There is little to no activity in the Mossel Bay,  Southern Cape area where I live.  So why not create activity?  I decided to embark on "The ZS1I - 6 Meter Magic Band Project in the Southern Cape Area of South Africa".  I am currently getting my equipment ready for this venture.  

Now one need a few handy "tools" to assist you in "playing" on the 50 Mhz band.  In future articles I will explain what I am using and how I set it all up.  Apart from a radio, computer, firmware, antennas etc.  I was looking for an easy and relative cheep way to spot openings on the 6 Meter band and also to monitor WSPR signals.  The setup must be fully automated and be able to send spots to WSPRNET.  Another must have was the function to use a Telegram phone alert bot that pushes an instant notification to my smartphone the exact millisecond the monitor intercepts an opening on 6 Meters.

Now what is a Compact Low Power Automated WSPR Monitoring Station?

An automated WSPR Monitoring Station is a compact, low-power radio receiver setup. It listens for specific Weak Signal Propagation Reporter (WSPR) radio signals transmitted by amateur radio operators globally.

Image:  Raspberry Pi Zero 2 W  (Click on image for larger view.)

Here is a breakdown of what it is and what it is used for:

What It Is

• The Brain: A Raspberry Pi Zero 2 W microcomputer running automated listening software like rtlsdr-wspr or WSJT-X.
• The Operation: It runs 24/7, automatically tuning to specific radio frequencies, decoding digital WSPR signals, and uploading the data to the internet via Wi-Fi.

What It Is Used For

• Atmospheric Testing: It measures how well radio waves travel through Earth's ionosphere at any given moment.
• Antenna Benchmarking: It helps operators see how well their antennas perform by checking if their signals can reach your station.
• Space Weather Tracking: It monitors how solar flares, sunspots, and day/night cycles affect global radio communications.
• Data Crowdsourcing: It automatically uploads reports to WSPRnet, contributing to a live, global map of radio propagation.
• Catching Band Openings: It acts as an early warning system, instantly detecting when changing atmospheric conditions suddenly allow signals to travel thousands of kilometers on a previously "dead" frequency. 

Here is how the system works from the antenna to your phone.

Image:  RTL SDR Receiver V4  (Click on image for larger view.) 

1. Recording the Spots

• The Radio: Your SDR dongle constantly listens to a set radio frequency (like 14.0956 MHz for the 20-meter band).
• The Software: Digital software on the Pi cuts the audio into strict two-minute windows.
• The Decode: The software processes the audio to extract the caller's call sign, grid square, and signal strength.The Local Log: Every successfully decoded message is instantly written to a local text file called ALL_WSPR.TXT.

2. Sending Spots to WSPRnet

• The Upload: Right after writing to the local log, the software uses your Wi-Fi to bundle the data.
• The Network: It sends an automated internet request to the central WSPRnet database.
• The Map: Your station’s data joins thousands of others to update global propagation maps in real time.

Image:  Telegram Bot  (Click on image for larger view.)

3. Connecting Smartphone Push Alerts (Telegram)

To get instant alerts when a specific distance or rare call sign is logged, you connect a custom script to your log file:

• Create the Bot: You message @BotFather on Telegram to create a free bot and get an API Token.
• Get Your ID: You message @userinfobot to find your personal Telegram Chat ID.
• Monitor the Log: You run a lightweight Python or Bash script on the Pi that actively watches (tails) the ALL_WSPR.TXT file for new entries.
• Trigger the Alert: The script checks each new line. If it meets your criteria (e.g., a signal from > 5,000 km away), it sends a web request to Telegram, and your phone buzzes instantly. 

Beneath is a few decodes on 40 meters run with the current test setup: 

 

Images:  Decodes  (Click on image for large view.

I have ordered a few "goodies" that will be used to complete the project.  In Part 2 we will be looking at the setup and use of the WSPR Monitoring Station.  I will also look at setting up an automated band monitor for FT8. Very similar to the WSPR Monitoring Station except that we need much more processing power and a wider bandwidth.  More on this in a future posting.

Update: The ZS1I - 6 Meter Magic Band Project in the Southern Cape Area of South Africa. (Part 2)

Image:  AI  (Click on image for larger view.)

My mind has been filled with many projects that I would like to construct in the next few years.  Only time will tell if this will be possible as many unforeseen things can happen that prevent me from completing projects.  Now one of the projects that I work on from time to time is the 6 Meter Magic Band Project in the Southern Cape Area of South Africa.  Read more HERE about this project.

I have been reading every single day to gain as much knowledge and information as possible on the various projects that I am busy constructing or putting together.  What a great privilege to still have good health and eye sight  that makes reading and learning possible.

Awhile ago I completed the 6 Meter CW Beacon but it is still not on the air.  One reason for this is I will have to relinquish other RF radio systems to ensure that I have optimal "conditions" in and around the shack for 6 Meter operations.   I also need to use current antenna poles to install 6 Meter antennas.  I need to remove the 2 Meter antenna pole to be used for 6 Meters. 

Be as it may my brain runs in "overdrive" when it comes to amateur radio ideas and projects.  I came up with the following question:

Which mode, CW or WSPR is better for a 6 meter magic band project? The ZS1I 6 meter magic band project for amateur radio involves building or using equipment (radios, antennas) to exploit the unique, unpredictable long-distance propagation (Sporadic-E, F2 skip, Aurora) on the 50-54 MHz frequency, offering both short-range VHF and surprise HF-like DX (long-distance) contacts, often using simple DIY antennas like halo loops or Moxons for great results and rewarding challenges. Projects focus on maximizing these propagation modes, especially during peak seasons like summer (Sporadic-E) and solar maximums (F2).

I was interesting to find out what mode will provide the "better"  outcome taking into account the local factors in the Southern Cape and the equipment I will be using to achieve ultimate success with the 6m project.

I decided to call on AI to answer my question: 

"The question of whether a WSPR (Weak Signal Propagation Reporter) beacon or a traditional CW (Morse Code) beacon is "better" for the 6-metre band (50 MHz) depends entirely on how you plan to monitor the band and what equipment you want to use.

---

Direct Comparison

Feature	WSPR Beacon	CW Beacon
Sensitivity	Superior (Decodes down to -28 to -31 dB SNR)	Inferior (Human ear cuts off around -10 to -15 dB)
Required Equipment	Radio + Computer/Interface or dedicated digital transmitter	Just a standard receiver (and your ears)
Reporting Network	Automated logging to WSPRnet	Dependent on the Reverse Beacon Network or manual logs
Bandwidth	Ultra-narrow (~6 Hz per signal)	Narrow (~100-200 Hz)
Time to Results	2-minute fixed transmission cycles	Instantaneous identification

---

Why WSPR is Better

• Extreme Weak-Signal Decoding: WSPR is specifically designed to dig deep below the static. It can decode signals as low as -31 dB SNR. This allows you to spot micro-openings or tropospheric ducting paths on 6 metres that a human ear scanning a CW frequency would completely miss.

• Set-and-Forget Automation: When you leave a WSPR beacon running, automated listening stations worldwide upload the data directly to WSPRnet. You can pull up a live map on your phone or PC to see exactly where your 6-metre signal is landing without relying on anyone manually copying your Morse code.

• Ultra-Low Power: Because of its heavy forward error correction (FEC), you can run a 6-metre WSPR beacon on just a few milliwatts to 1 Watt and still get spots thousands of miles away.

Why CW is Better

• Instant Band Awareness: 6 metres is known as the "Magic Band" because it can open to sporadic-E propagation instantly. WSPR takes exactly 2 minutes per transmission cycle to decode. If you are actively sitting at your desk waiting for a band opening to make contacts (like FT8 or SSB), listening to a cycling CW beacon provides immediate auditory confirmation the second the band pops open.

• No Computer Required: You don’t need an interface, software (like WSJT-X), or precise GPS time-syncing to use a CW beacon. You just spin the dial to the 50.000–50.100 MHz beacon sub-band and listen.

• Indicator of Communication Readiness: If you can hear a CW beacon with your ears, the band is open enough to support live, two-way human communications (SSB, CW, or FT8). WSPR signals can be decoded even when the path is too weak to support a normal conversation.

---

The Verdict

• Choose WSPR if your goal is long-term propagation research, antenna testing, or seeing if a path exists when the band appears "dead".

• Choose CW if you are an active operator waiting to jump on the radio the moment 6 metres opens up for live voice or Morse code contacts."

Many modern beacon builders actually combine the two by setting up a transmitter that alternates—sending a 2-minute WSPR cycle followed by a brief CW identification so that both digital systems and human ears can utilize the signal!

There you have it.  I will have to make a decision as to whether I will be going the WSPR or CW "route".   The decision is quite simple.  

AI makes it easy: 

"Operating from KF15BT (located in the beautiful but radio-isolated Southern Cape region of South Africa, near Mossel Bay/George), you are uniquely positioned for long-distance DXing via interesting propagation modes, but you face the classic "lonely ham" problem. Because there is little to no local 50 Mhz activity to keep the band warm, you must rely entirely on automated "triggers" to tell you when a long-distance opening is happening. 

Given your excellent gear (6 Meter Yaesu Radio, Moxon, Delta Loop) and your homebrew Arduino/ESP32 hardware, digital modes (specifically FT8 for contacts and WSPR for monitoring) are absolutely the way forward. 

Here is the exact strategic blueprint for conquering the "Magic Band" completely solo from your grid square.

The Strategy: Digital over CW

    • The FT8 Reality: 95% of global 6m DX hunting is concentrated on 50.313 MHz (FT8). If the band opens from South Africa to Europe, South America, or up into Africa, those stations will be parked on FT8 waiting for signals. 

    • The Problem with CW: If you sit and text CQ on CW, no one will hear you unless their beam is pointed directly at KF15. Most European or DX stations leave their rigs automated on FT8 overnight or during the day to catch rare openings. "

For raw technical performance and automated global tracking, WSPR is vastly superior. However, for real-time human monitoring and instant "radio-in-hand" notification of sporadic-E band openings, CW beacons remain highly essential."

These last three lines is the crux of my question and answer. I will be using WSPR which is vastly superior and will hopefully provide the best outcome for the project. Along the way I will however also make use of CW. Time to get to work!

Is this possibly the end of the road for the ZS1I AllStar RF Link on 145.550 Mhz in Mossel Bay?

Image: AI (Click on the image for larger view.)

Is this possibly the end of the road for the ZS1I AllStar RF Link on 145.550 Mhz?  For the time being the ZS1I AllStar RF Link on 145.550 Mhz in Mossel Bay has been switched off and will not be available until further notice.

The following reasons are being presented as to why this decision has been taken:

1.  The 145.550 Mhz RF Link is solely being used by yours truly in and around the household.  Running at 25 watts output power this is a waste of RF energy and unnecessary stress on equipment.  To those that do not talk but listen (gooi varkoor) unfortunately you will have to find another source to listen.

2.  I have the following radio equipment running every day in the shack.

• DMR Repeater
• WSPR Beacon
• 2m RF Simplex Link
• 6 cm CW Beacon
• 70 cm RF Simplex Link (at times when necessary)
• 2 x WiFi Routers
• 5.8 Ghz AREDN Node 

I am getting ready for the 6 Meter "Magic Band" Season that will soon commence.  I want to keep RF levels in and around the shack as low as possible.  This will entail switching of other RF radio equipment that does not get used regularly.  

3.  I have indicated before that I want to concentrate more on DMR and 6 Meter Operation. Well the time has arrived for just doing that.  Unfortunately I will have to relinquish other systems to ensure that I have optimal "conditions" in and around the shack for DMR and 6 Meter operations.

4.  I also need to use current antenna poles to install 6 Meter and 70 cm antennas.  I will therefor remove the 2 Meter antenna pole to be used for 6 Meters.

5.  The current EMI / Ground Level Noise is running quite high in the shack due to various outside factors.  I need to lower this noise factor and need to eliminate the source of this noise if possible.  I will use the process of elimination to hopefully solve the high noise level. 

6.  I intend using separate TX and RX equipment for 6 Meters.  Power output will also differ depending on the mode of communication.  I do not want to run any equipment that is not being utilized regularly.  I will run all equipment from solar power, hopefully noise free!

There you have it.   Will the ZS1I AllStar Hub in Mossel Bay still be available and operational for use by radio amateur?  YES, it will work as before, just without the 2m RF Link on 145.550 Mhz.  I will monitor the running systems and might utilize the 145.550 Mhz RF Link again in future when the need arise.