Booting the Clone
It starts with a click of the power button on the sleek LibreSDR B220 clone. The screen lights up with a reassuring green glow, and a soft chirp signals that the firmware is ready. The tiny desktop computer, a Raspberry Pi 4, boots up and launches CubicSDR almost instantly. I pull up the software, open the Control Panel, and hand the device a “mute, then read” order—a ritual that guarantees a clear listening window.
Setting the Frequency Dial
WSPR is all about those precise carrier tones. On the 2‑meter band, I slide the frequency dial to 145.000 MHz. The software draws the spectrum, and faint tones begin to appear like whispers in the static. The lock-in feature of CubicSDR keeps the local oscillator firmly anchored, preventing the slave processor from drifting during long receive runs.
Diving into the 70‑Centimeter Window
When I switch to the 70‑centimeter band, I set the SDR to 435.000 MHz. The scenery changes—the noise spectrum becomes richer, yet the WSPR signal remains strikingly narrow at 1 Hz bandwidth. The software’s narrowband filter, set to 10 kHz, isolates the carrier cleanly. After a few minutes, the plug‑in signals reveal the decoding hashes of distant stations, each line a testament to the deep‑space dreams of amateur radio enthusiasts.
Looking for the spectral ghosts on 23‑centimeters
I then venture into the 23‑centimeter band, tilting the dial to 1240.000 MHz. The device’s LF design tracks low‑frequency settles with finesse, providing a smooth sweep of the spectrum. The WSPR outbursts appear as soft glints in the top of the display, sporadically catching the eye. The moments between outbursts feel like breathing—short, but necessary.
Chasing the Transient in the 10‑Meter Band
The 10‑meter band reads around 280.000 MHz for WSPR. The software’s spectrum window shows sharp, narrow spikes that march up the frequency axis as the receive window rotates. The LNB converter’s gain, set to moderate, prevents overload while keeping sensitivity high. I note the offset difference each 10‑meter hop; it’s a small step, yet each station’s unique fuzzy message appears in the decoded log.
Grasping the Nuances of the 6‑Meter Frequency
On 50.000 MHz, the 6‑meter WSPR carriage carrying silent messages traverses the ionosphere. The SDR’s high‑band circuits, final‑stage amplifier and mixer, demonstrate robust performance in the higher frequency range. The spectral trace shows the precise 1‑Hz pulses, unspooled by CubicSDR into printable XYZ‑grid maps. My monitor fills the screen with an intricate lattice of dot traces that speak of a vast network around the world.
Calibration and Fine‑Tuning
Every measurement session starts with a calibration step. I lock the signal at 145.000 MHz and use a known reference tone—
A Quiet Morning and the LibreSDR B220 Clone
When the first rays of sunrise brushed the hills, I settled at my desk with a steaming mug of coffee and the LibreSDR B220 clone humming quietly on the bench. The device, a faithful reproduce of the original B220, gleams with a sturdy aluminum chassis and a single B‑and‑B connector, ready to dive into the world of shortwave and MF/HF bands. Its powerful 28‑bit, 24‑bit ADC and a 137 Hz‑resolution tuner make it an excellent tool for anyone exploring the WSPR-15 sphere, where whispers of near‑once‑in‑a‑million signals cross the air.
The WSPR-15 Band Hunt
WSPR-15 vectors as a **four‑tone push‑pulsed** methodology, perfect for weak‑signal experiments. The signal occupies an extremely narrow slice of the spectrum – about 2.4 kHz of bandwidth – which means we can span a wide range of amateur bands without being overwhelmed by interference. The equalization across the sweep is a defining characteristic of the clone, allowing it to lock onto a 15‑second burst with astonishing fidelity.
Guided by the latest recommendations from the amateur band plan, I started my sweep at the 160 m band, a favorite haunt for WSPR. The B220’s built‑in fine‑tuners slid the SDR to 2 397 kHz, placing the 20 Hz carrier exactly in the middle of the 2 380 kHz–2 440 kHz slot. Python‑based scripts then received the 15‑second frames and plotted the pattern in real time. The visible flares on the spectrogram matched the forum reports, confirming that the clone survives the **ITU‑regional allocation** with excellent clarity.
Following the Trail Across Bands
Next came the 80 m band. By
The Day the Radio Beckoned
In a small apartment on the third floor, Alex found an old power supply in the attic—a relic that hummed quietly. He pulled it out, wiped the dust, and when the glow of the screen flickered, a story began: a story of waves, frequencies, and a quiet network of voices that shared a language of dots and dashes.Setting the Receiver
The heart of the tale is a LibreSDR B220 clone, a device that feels like a bridge to the unseen. Alex started by tightening the SMA connector on the antenna strap, letting the iron straps embrace the fine copper. He turned the software to “RTL-SDR → PortaFOE” and pulled the frequency slider to 146.520 MHz, the magical starting point of FT‑8’s first starburst on the 2 m band. A gentle click echoed, and the display bloomed with a silvery sweep of the band. For a refined listening experience, he tuned the RF gain to a moderate level, ensuring that the narrow 6.25‑kHz sub‑band for FT‑8 remained crisp. The software’s waterfall plot revealed a faint rose as the signal gulped in, a preamble that only a few could notice without the right eye.Hunting the Silent Signals
The B220’s capacitive divider, at its heart, allowed a shimmer of the 14 MHz band to reach Alex’s screen. He shifted the frequency to 7.052 MHz to listen for FT‑8 mooncake signals on the 40 m band, a practice he had read about on a recent ham radio forum thread where enthusiasts batch‑saved a real‑time feed of global ham signals. When the tuner drifted to 21.052 MHz on the 15 m band, the quiet chatter of the open band called his attention. The spectral density of the background noise lowered to a bath of electric grey, and the soft chirp of FT‑8 nodes broke through like an echo in the canyon.Decoding the Language of FT‑8
With Fldigi added to his toolkit, Alex set the mode to FT‑8, tuned the audio scaling to match the SDR’s 48 kHz sample rate, and listened. The sounds were like Morse in digital form, a tinny burst of 40 Hz spikes that the software turned into readable grids. Each burst—formed on the 15‑second cycle—brought a new station identity, a new call sign that appeared in the log. He noted that the staples of FT‑8 use frequencies at the three billionths jumps: 14.629 MHz, 21.629 MHz, and 28.629 MHz for 20 m, 15 m, and 10 m respectively. The LibreSDR’s gentle stability meant these nodes would appear almost verbatim, and Alex recorded a full session with a sharp accuracy that surpassed his previous digital attempts.The Global Call
When the sun rose over the horizon, a new set of nodes kept popping in from worlds away. In a particularly bright afternoon, Alex received a wave from VK9TS in Australia, a compressed burst in the vexillated 8 Hz band that fluttered just above 14.585 MHz. His screen glowed red, and his logbook filled with a packet that would later be gleamed back to a lunar echo. The B220’s simplicity allowed Alex to see the patterns. He found the more elaborate graphs from recent discussions on the LibreSDR user community—a notebook that listed bandwidth for FT‑8 as only 6.25 kHz. By sliding the block bandwidth window, he could isolate each packet and examine the spectral peaks that heralded each transmission.A New Chapter Begins
With a few more hours of tuning between 146.520 MHz on the 2 m band and 21.052 MHz on the 40 m band, Alex wrapped up his session. The old power supply flickered one last time, and the silence that followed was a promise of more voices to come. The LibreSDR B220 clone, a humble valley of circuitry, had opened a bridge to a network of silent radio stars. And Alex knew that the next day would carry another story, another relay of signals on this vast digital canvas.Unveiling the FT‑4 Signals
When the sun dips below the horizon over the high‑rolling hills, the sky becomes a canvas painted with fleeting bursts of radio energy. As an amateur radio enthusiast who lives for those intermittent glimmers, I was eager to use the LibreSDR B220 clone to chase the elusive FT‑4 signals that have recently been discussed in the latest July Amateur Radio Journal.
Setting Up the LibreSDR B220 Clone
First, I soldered the B220’s tiny SMA connector to a rugged 9‑inch dipole tuned to the 70‑centimeter band around 446 MHz. The clone’s 28 MHz to 24.5 GHz front‑end was later calibrated with its built‑in calibration signal, ensuring the mixer stage maintained a flat response across the entire 70‑cm and 2‑meter allocations.
Discovering the Frequencies
Guided by the recent journal notes, I began scanning the 2‑meter band for the FT‑4 carriers that are believed to sit between 144.030 MHz and 144.045 MHz. A shortbut intense burst of wideband bursts at about 144.036 MHz appeared on the waterfall, accompanied by an FM sweep that matched the time‑stamp of a satellite pass noted in the logbook. Meanwhile, the 70‑centimeter band revealed a faint pulsed burst at precisely 446.750 MHz, confirming the dual‑band operation of the FT‑4 system.
Charting the Spectrum
With the SDR software’s demodulation kit running, I captured a full hour of spectrum data. The FT‑4 bursts exhibited a digital phase‑shift keying modulation, each symbol lasting about 2.5 ms. Using the clone’s software‑defined quadrature demodulator, I extracted the message log and cross‑referenced it with the frequency database supplied by the recently published Free Amateur Bands 2024 guide.
Why the B220 Clone Works So Well
The clone’s low‑noise amplifier and the ability to program the frequency offset directly in the firmware means I could tweak the gain to a point where the faint FT‑4 tones were no longer a background hiss but a crisp, audible signal. The 300 kHz bandwidth of the B220’s internal mixer was perfectly suited to the FT‑4 bandwidth of 250 kHz, allowing all the sub‑carrier information to pass through without distortion.
Final Thoughts
In the end, the mission of quiet monitoring paid off. The LibreSDR B220 clone proved its worth not only as a cost‑effective replacement for commercial SDR hardware, but as a reliable partner in unlocking the secrets of the FT‑4 amateur radio frequencies. With the 144.036 MHz and 446.750 MHz footprints now archived, the next step is to stack the observed data into a public database, giving the community a new source of insight into these fleeting transmissions.
The Open Sky of 2024
On a quiet Saturday morning, the old wooden radio shack was suddenly alive with the humming of a brand‑new LibreSDR B220 clone. The little box—a faithful replica of the original SDRplay RSP1—stretched from 1.7 MHz to 2 400 MHz, and I felt the urge to explore that vast frequency earth as if it were a hidden world waiting to be charted.
Fine‑Tuning the Receiver
With SDR#.net opened beside a glass slab of digiscale, I set the center frequency to the 28 MHz band, a region most ham enthusiasts call the “11‑meter band.” A sweep revealed a pattern of faint, regular beats that pulsed in sync with a digital burst—just the hint of MT‑63, a modern weak‑signal mode popular among amateur radio operators for its resilience in noisy places.
MT‑63 is not a single frequency; it thrives where the signal carriers fall within defined sub‑bands. The most common stations on the 28 MHz band lie between 28.45 MHz and 28.70 MHz. I concentrated on 28.579 MHz, a traffic‑hot spot on the local repeater, where the MT‑63 data packets swelled to their full glory. The LibreSDR’s 5 MHz bandwidth was more than enough to capture the entire set of lower‑ and upper‑sidebands, while the GNU Radio flow‑graph I streamed into the mixer gave me a clean, real‑time spectrum.
Curiosity led me beyond the morning fog. On the 2 m band (144.300 MHz–144.350 MHz) I switched the tuner to 144.315 MHz, a favourite for weak‑signal networks. The “MT‑63 burst” repeated every minute, along with a nearby JT9 chirp. When I turned the frequency higher to the 70 cm band (420.000 MHz–420.375 MHz), I found a second MT‑63 chatter on 420.225 MHz—an unexpected echo from a distant club in the Midwest. These frequencies, though separated by more than a thousand megahertz, were linked by the same robust modulation technique
The Unexpected Find
A crisp winter morning in early 2026, I unboxed the LibreSDR B220 clone, a marvel of open‑hardware engineering that promised a broad frequency range reaching from 3 MHz to 50 MHz. When I first powered it on, the tiny display flickered to life, and I was immediately drawn to the idea of sipping the airwaves that had carried ham‑radio dreams since the 1920s. No emoticons, no bullet lists – just a quiet anticipation as the SDR's firmware rolled out the latest updates for better tuner resolution and reduced interference.
Preparing the Workspace
I set my B220 against the wall of my makeshift ham shack, its steel chassis humming with a faint, static‑free tone. While the SDR was impressive, the real magic lay in the combination of a low‑noise preamplifier from the little workshop in town and a carefully tuned 1‑µm coaxial cable that carried the signal from the antenna to the SDR's dish‑shaped input. In my mind, I imagined the signal traveling across 10 MHz ∼ 30 MHz, traversing the loft, and arriving at the SDR’s heart where it would be decoded into tiny data bursts.
Learning the PSK‑31 Dance
PSK‑31, the beloved 31 Hz phase‑shift keying mode, roams the 10 m, 15 m, 20 m, and 40 m amateur bands—exactly where the B220 excels. In the United States, the FCC has carved out the following segments for PSK‑31: on 10 m, from 28.941 MHz to 28.959 MHz; 15 m, from 21.074 MHz to 21.106 MHz; 20 m, from 14.074 MHz to 14.106 MHz, and 40 m, from 7.048 MHz to 7.090 MHz. The B220’s wide‑band tuner makes it effortless to slide across each block, while the accompanying software allows for real‑time demodulation of the delicate 31‑Hz pace.
Into the Current Vein
With the SDR calibrated, I locked onto 28.956 MHz—a prime spot on the 10 m band, just a few hertz away from the upper edge of the allowed PSK‑31 range. The screen filled with a waterfall of frequency bins, and a faint tweedle‑tweedle noise emerged from the tranquil background. Then, a soft chirp crackled: a call to 8 O1A, pinging the 10 m channel. I responded in the same quiet, measured pressure, sending a brief exchange of latitude and longitude. The B220’s minimal latency meant we never missed a beat; the waveform stayed crisp, the phase jumps precise, and the RF noise barely drenched our link.
Reflections Over a Quiet Night
When the dawn broke on that winter day, I turned off the B220 and placed it back on the shelf, wiping the dust off the grid of tiny capacitors. The day had proven that a LibreSDR B220 clone is more than a piece of hardware; it is a bridge between generations—linking the daring pioneers who carved the 10 m band to the modern operators who now beam their PSK‑31 signals with digital precision. From the tinny quiet of the 7.050 MHz corner of 40 m to the fine‑tuned ladder of 28.957 MHz, the SDR’s comfort makes every staff, every call, and every silent burst a celebration of amateur radio’s enduring spirit.
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