His single-knob ESP32 radio can tune Argentina from Germany after shrinking the audio fourfold
A physical knob was the goal; packet diagnostics exposed why making the buffer larger could not cure the missing audio.
The radio in Germany was listening through a receiver in Argentina, and the sound kept cutting out. Adding more waiting room to the audio buffer helped only so far. ESPica32 needed less audio data arriving through the narrow part of the system.
The maker’s Spanish-language account describes a minimal physical client for KiwiSDR receivers: an ESP32, an OLED, one rotary encoder and an audio amplifier. The point was to turn a knob and hear a band without keeping a computer or phone in the listening loop.
The receiver itself still lives elsewhere. ESPica32 connects over Wi-Fi to a KiwiSDR and plays that receiver’s stream. Calling it a little shortwave receiver without that explanation would suggest a local antenna and radio front end that this build does not supply. The knob travels; the antenna stays home.
The author tried a larger buffer and clock-drift compensation, then added diagnostics that classified interruptions. That panel showed about 13.5 packets arriving per second against 23.4 needed in the reported case. A buffer cannot permanently manufacture the packets that never make it through at the required rate.
The fix used ADPCM compression at the Kiwi end and decompression on the ESP32. The maker reports reducing the audio stream from roughly 24 kB/s to 6 kB/s and obtaining clean audio. Those are results from this build and connection, rather than a guarantee for every distant receiver.
The arithmetic gives the story its practical bite: 24 ÷ 6 = 4, so the stated compressed rate is one quarter of the former rate. The exact figures are approximate. Turning that into a promise of four times better sound quality would be a different calculation entirely (and a very ambitious volume knob).
The ESP32-WROOM-32, OLED, encoder and MAX98357A amplifier also preserve a satisfyingly physical interface. Clicks move the encoder’s focus, and longer gestures change other settings. One knob saves parts while making the interaction vocabulary more important.
A builder trying the project could begin with the documented receiver configuration and a nearby stream before testing a distant one. That would help separate basic setup trouble from the long-distance audio problem the author describes. Replacing the knob because the network drops audio would be an unusually hands-on misunderstanding.
The transferable idea is to make interruptions explain themselves before repeatedly enlarging buffers. A measured arrival deficit points toward a data-rate or delivery problem; a sporadic scheduling delay can call for a different response. The diagnostic labels turned an audible annoyance into a choice between plausible fixes.
The project’s unfinished additions include a printed enclosure and frequency favorites. Those are useful next steps, but the little client already delivers its central trick: a familiar control connected to a receiver on another continent. A proper case can wait for the audio to finish crossing the ocean.
Now that is remote control.