Glossary

Glossary

Plain‑language definitions of terms used throughout this manual and on the radio's screens.

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AGC (Automatic Gain Control) — Circuitry/DSP that keeps loud and soft signals at a comfortable listening level. Options: OFF, SLOW, MED, FAST. Use SLOW for SSB, FAST for CW.

ANR (Automatic Noise Reduction) — A DSP feature that reduces background hiss to make voices clearer.

Band stack — The radio's per‑band memory. Each band remembers its own last frequency, mode, and settings, so switching bands returns you to where you left off. Saved across power cycles.

BFO (Beat Frequency Oscillator) — An oscillator used to produce the audio tone from a received signal; the BFO offset control fine‑tunes audio pitch.

Bug — A semi‑automatic Morse key that makes dits automatically but dahs manually. The zBitx can emulate one (CW_INPUT → BUG).

Break‑in / QSK — CW operating where the radio drops to receive between elements/characters so you can hear the other station almost instantly. Controlled by CW_DELAY.

CAT (Computer Aided Transceiver) — A control interface that lets a computer read and set the radio's frequency, mode, and PTT. Used by logging and digital software. The zBitx has a built‑in hamlib‑compatible CAT server.

COMP (Compressor) — Speech processing that raises your average transmit power, improving voice readability — especially valuable at QRP.

CW / CWR — Continuous Wave (Morse code). CWR is the reverse‑sideband variant; pick whichever gives correctly‑pitched signals on your band.

DIGI / Digital mode — Data modes sent as audio tones (FT8, RTTY, PSK, JS8, etc.).

DRIVE — Your transmit power level setting.

DSP (Digital Signal Processing) — The math the Pi does to demodulate, filter, and clean up signals. Also the name of the main noise/processing toggle.

DX — A distant station or contact. "DX spots" are reports of active DX stations.

Dummy load — A resistor that safely absorbs transmit power so you can test transmitting without radiating a signal. Use one when you don't have an antenna connected.

FT8 — A popular weak‑signal digital mode using 15‑second timed transmissions. Decoded and transmitted on the radio itself. Requires an accurate clock.

Grid / Maidenhead locator — A short code (e.g. EM79) identifying your location, exchanged in FT8 and shown on the grid map.

Hamlib — A widely‑used library/standard for computer rig control. The zBitx's CAT server speaks it, so most logging and digital software can control the radio.

Headless — Running the Pi application without its graphical (GTK) window — the configuration used when the front panel and web interface are the control surfaces rather than a monitor on the Pi.

I2C — The two‑wire communication bus the Pi and the front‑panel Pico use to exchange field values and commands.

Iambic (mode A / B) — Paddle keyer behavior. Mode A and Mode B differ in what happens when you release both paddles mid‑character. Set via CW_INPUT.

IP address — The radio's address on your network (e.g. 192.168.1.42), shown on the WiFi status line. Type it into a browser to reach the web interface.

LSB / USB — Lower and Upper Sideband, the two SSB voice modes. LSB below 40 m by convention; USB on 20 m and up.

Macro — A stored message (CQ call, exchange, etc.) the radio can send for you in CW or FT8.

Notch filter — A filter that removes a single steady interfering tone (like a carrier) from your receive audio.

PTT (Push To Talk) — The control that switches the radio from receive to transmit.

QRP — Low‑power operating, generally 5 watts or less. The zBitx is a 5‑watt QRP radio.

RIT (Receiver Incremental Tuning) — Nudges your receive frequency without moving your transmit frequency — useful when a station is slightly off your frequency.

RR73 / 73 — Standard FT8/CW sign‑offs. RR73 means "received, roger, best regards" (confirms the QSO); 73 means "best regards."

SPAN — How wide a slice of the band the spectrum/waterfall displays (25 K / 10 K / 6 K / 2.5 K).

SSB (Single Sideband) — The main HF voice mode (USB or LSB).

STEP — How much the frequency changes per click of the tuning knob (10 K down to 10 Hz).

Straight key — A simple up/down Morse key. Select CW_INPUT → STRAIGHT.

SWR (Standing Wave Ratio) — A measure of how well your antenna is matched. 1:1 is perfect; keep it under about 2:1. High SWR means a poor match — retune or move frequency.

Sidetone — The tone you hear locally while sending CW (not transmitted). Set its pitch/level to taste.

TNPWR / TNDUR — Tune power and tune duration: the power level and time length of the tune carrier used to adjust an antenna tuner.

TXMON (Transmit Monitor) — Lets you hear your own transmitted audio to check quality.

Ultimatic — A keyer mode where holding both paddles sends a stream of the last‑pressed element. Select CW_INPUT → ULTIMAT.

UF2 — The file format used to flash firmware onto the RP2040 (Pico) by drag‑and‑drop. The front‑panel firmware is distributed as a .uf2.

VFO (Variable Frequency Oscillator) — Your tuning "dial." The radio has VFO A and VFO B, used for split operation and quick frequency swaps.

VNC — A way to view and control the Pi's graphical desktop remotely — here, inside your web browser via the VNC button.

Waterfall — The scrolling display beneath the spectrum that paints signal history over time, making intermittent signals easy to spot.

WFCALL — A former feature that transmitted your callsign as a visible pattern in the waterfall. Removed from later builds on some hardware.

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