{
  "terms": [
    {
      "code": "AM",
      "category": "Betriebsart",
      "meaning": "Amplitudenmodulation — amplitude modulation.",
      "exam": true,
      "explanation": "The carrier amplitude follows the audio signal. Both sidebands and the carrier are transmitted, so AM needs more bandwidth and power than SSB."
    },
    {
      "code": "FM",
      "category": "Betriebsart",
      "meaning": "Frequenzmodulation — frequency modulation.",
      "exam": true,
      "explanation": "The carrier frequency follows the audio signal at constant amplitude. Robust against amplitude noise; the usual mode for VHF/UHF (UKW) voice and repeaters."
    },
    {
      "code": "PM",
      "category": "Betriebsart",
      "meaning": "Phasenmodulation — phase modulation.",
      "exam": true,
      "explanation": "The carrier phase follows the signal; closely related to FM and often used to generate it."
    },
    {
      "code": "DSB",
      "category": "Betriebsart",
      "meaning": "Doppelseitenbandmodulation — double-sideband modulation.",
      "exam": true,
      "explanation": "Both sidebands are transmitted. The carrier may be present, as in conventional AM, or suppressed, as in DSB-SC; suppressing one of the two sidebands produces SSB."
    },
    {
      "code": "SSB",
      "category": "Betriebsart",
      "meaning": "Einseitenbandmodulation — single sideband.",
      "exam": true,
      "explanation": "Only one sideband is transmitted and the carrier is normally suppressed. Compared with conventional AM, SSB uses about half the bandwidth and does not waste transmitter power on a full carrier, which is why it dominates analogue HF voice."
    },
    {
      "code": "USB",
      "category": "Betriebsart",
      "meaning": "oberes Seitenband — upper sideband.",
      "exam": true,
      "explanation": "SSB using the sideband above the suppressed carrier. Convention on HF above 10 MHz and on VHF/UHF."
    },
    {
      "code": "LSB",
      "category": "Betriebsart",
      "meaning": "unteres Seitenband — lower sideband.",
      "exam": true,
      "explanation": "SSB using the sideband below the suppressed carrier. Convention on the HF bands below 10 MHz (160/80/40 m)."
    },
    {
      "code": "CW",
      "category": "Betriebsart",
      "meaning": "Continuous Wave — Morsetelegrafie (A1A).",
      "exam": true,
      "explanation": "On/off keying of an unmodulated carrier. Very narrow bandwidth and excellent weak-signal readability."
    },
    {
      "code": "FSK",
      "category": "Betriebsart",
      "meaning": "Frequency Shift Keying — Frequenzumtastung.",
      "exam": true,
      "explanation": "Digital keying that shifts the carrier between discrete frequencies; the basis of RTTY."
    },
    {
      "code": "PSK",
      "category": "Betriebsart",
      "meaning": "Phase Shift Keying — Phasenumtastung.",
      "exam": true,
      "explanation": "Digital keying that encodes data in carrier phase shifts."
    },
    {
      "code": "ASK",
      "category": "Betriebsart",
      "meaning": "Amplitude Shift Keying — Amplitudenumtastung.",
      "exam": true,
      "explanation": "Digital symbols are represented by discrete carrier amplitudes. Simple on-off keying is the two-state special case; unlike FM or PSK, amplitude noise directly affects the keyed quantity."
    },
    {
      "code": "QAM",
      "category": "Betriebsart",
      "meaning": "Quadraturamplitudenmodulation — quadrature amplitude modulation.",
      "exam": true,
      "explanation": "Combines amplitude and phase modulation on two quadrature carriers to carry several bits per symbol."
    },
    {
      "code": "RTTY",
      "category": "Betriebsart",
      "meaning": "Radioteletype — Funkfernschreiben.",
      "exam": true,
      "explanation": "Classic teleprinter operation using frequency-shift keying and the five-bit ITA2 alphabet, commonly called Baudot. On amateur HF it is usually copied with software rather than a mechanical teleprinter."
    },
    {
      "code": "PSK31",
      "category": "Betriebsart",
      "meaning": "Phase Shift Keying at 31.25 baud — narrowband keyboard digital mode.",
      "exam": true,
      "explanation": "The name is conventionally rounded: the symbol rate is 31.25 baud. This live keyboard-to-keyboard HF mode is very narrow, but overdriving an SSB transmitter produces a needlessly wide, distorted signal."
    },
    {
      "code": "FT8",
      "category": "Betriebsart",
      "meaning": "digitale Schwachsignal-Betriebsart (WSJT-X) — weak-signal digital mode.",
      "exam": true,
      "explanation": "A structured weak-signal mode with synchronized 15-second periods and short, highly constrained exchanges. It can decode signals far below the audible noise floor, but it is intended for brief contacts rather than conversation."
    },
    {
      "code": "WSPR",
      "category": "Betriebsart",
      "meaning": "Weak Signal Propagation Reporter — Bakenbetrieb zur Ausbreitungsforschung.",
      "exam": true,
      "explanation": "Very low-power beacon mode whose reception reports are pooled to map propagation."
    },
    {
      "code": "SSTV",
      "category": "Betriebsart",
      "meaning": "Slow Scan Television — Schmalband-Bildübertragung.",
      "exam": true,
      "explanation": "Sends still pictures slowly enough to fit a voice-bandwidth channel."
    },
    {
      "code": "ATV",
      "category": "Betriebsart",
      "meaning": "Amateurfernsehen — (fast-scan) amateur television.",
      "exam": true,
      "explanation": "Real-time video, typically on the higher bands because of its wide bandwidth."
    },
    {
      "code": "NBFM",
      "category": "Betriebsart",
      "meaning": "Schmalband-FM — narrowband FM.",
      "exam": true,
      "explanation": "FM with limited frequency deviation and occupied bandwidth. It is the normal analogue voice mode on VHF/UHF repeaters and simplex channels; channel spacing and occupied bandwidth are related but are not the same quantity."
    },

    {
      "code": "MF",
      "category": "Band",
      "meaning": "Medium Frequency — 300 kHz to 3 MHz (Mittelwelle).",
      "exam": true,
      "explanation": "The ITU band containing the amateur 630 m and 160 m allocations. In practice these low bands need large or electrically shortened antennas and are strongly affected by ground loss and nighttime propagation."
    },
    {
      "code": "KW",
      "category": "Band",
      "meaning": "Kurzwelle — shortwave, 3 to 30 MHz.",
      "exam": true,
      "explanation": "The German name for the ITU HF band. This is the classic long-distance amateur range, where ionospheric propagation can support regional or worldwide contacts."
    },
    {
      "code": "UKW",
      "category": "Band",
      "meaning": "Ultrakurzwelle — German name for 30 to 300 MHz.",
      "exam": true,
      "explanation": "Mostly line-of-sight propagation; home of FM voice and repeaters. In the BNetzA band names UKW is exactly VHF; 300 MHz to 3 GHz is UHF / Dezimeterwelle. Colloquially 'UKW' is sometimes stretched to mean VHF and up, but that is not the exam definition."
    },
    {
      "code": "VHF",
      "category": "Band",
      "meaning": "Very High Frequency — ITU band from 30 to 300 MHz.",
      "exam": true,
      "explanation": "The international designation corresponding to German UKW. The 2 m amateur band is the main practical example, used for local SSB/CW, FM simplex, repeaters, satellites and weak-signal work."
    },
    {
      "code": "UHF",
      "category": "Band",
      "meaning": "Ultra High Frequency — 300 MHz to 3 GHz.",
      "exam": true,
      "explanation": "Includes the amateur 70 cm, 23 cm and 13 cm bands. Propagation is mainly line of sight, although repeaters, satellites, tropospheric enhancement and reflection can extend the range."
    },
    {
      "code": "SHF",
      "category": "Band",
      "meaning": "Super High Frequency — 3 to 30 GHz (Mikrowellen).",
      "exam": true,
      "explanation": "Microwave range containing several amateur bands. Feed-line loss, connector quality and accurate antenna alignment become increasingly important, so the transverter or low-noise amplifier is often mounted near the antenna."
    },
    {
      "code": "EHF",
      "category": "Band",
      "meaning": "Extremely High Frequency — 30 to 300 GHz.",
      "exam": false,
      "explanation": "Millimetre-wave range containing experimental amateur allocations. Operation is specialized because atmospheric absorption, mechanical tolerances and feed-line losses are severe."
    },

    {
      "code": "NF",
      "category": "Signal & Frequenz",
      "meaning": "Niederfrequenz — audio frequency (about 16 Hz to 20 kHz).",
      "exam": true,
      "explanation": "The baseband audio signal before modulation or after demodulation."
    },
    {
      "code": "HF",
      "category": "Signal & Frequenz",
      "meaning": "Hochfrequenz — German technical term for a radio-frequency signal.",
      "exam": true,
      "explanation": "In German circuit descriptions, HF contrasts with NF and can mean radio-frequency energy generally. In the international ITU band names, however, HF specifically means 3 to 30 MHz; the German exam normally calls that range KW. Context decides which use is intended."
    },
    {
      "code": "ZF",
      "category": "Signal & Frequenz",
      "meaning": "Zwischenfrequenz — German abbreviation for intermediate frequency.",
      "exam": true,
      "explanation": "The fixed frequency a superheterodyne receiver mixes the signal to, where most selective amplification and filtering happens."
    },
    {
      "code": "IF",
      "category": "Signal & Frequenz",
      "meaning": "Intermediate Frequency — English abbreviation for an intermediate frequency.",
      "exam": false,
      "explanation": "English-language manuals and schematics use this where German material uses ZF. A superheterodyne receiver converts the wanted signal to this fixed frequency for most of its filtering and gain."
    },
    {
      "code": "RF",
      "category": "Signal & Frequenz",
      "meaning": "Radio Frequency — English term for a radio-frequency signal.",
      "exam": false,
      "explanation": "The usual English label for signals and circuitry at radio frequencies. German schematics commonly label the same signal domain HF."
    },

    {
      "code": "VFO",
      "category": "Baugruppe",
      "meaning": "variabler Oszillator — variable frequency oscillator.",
      "exam": true,
      "explanation": "The tunable oscillator that sets the operating frequency of a transmitter or receiver."
    },
    {
      "code": "VCO",
      "category": "Baugruppe",
      "meaning": "spannungsgesteuerter Oszillator — voltage-controlled oscillator.",
      "exam": true,
      "explanation": "An oscillator whose frequency follows a control voltage; the tunable element inside a PLL."
    },
    {
      "code": "PLL",
      "category": "Baugruppe",
      "meaning": "Phasenregelschleife — phase-locked loop.",
      "exam": true,
      "explanation": "Locks a VCO to a stable reference by comparing phase, forming the basis of modern frequency synthesizers."
    },
    {
      "code": "DDS",
      "category": "Baugruppe",
      "meaning": "direkte digitale Synthese — direct digital synthesis.",
      "exam": true,
      "explanation": "Generates a signal numerically from a clock and a phase accumulator, giving fine, fast frequency steps."
    },
    {
      "code": "BFO",
      "category": "Baugruppe",
      "meaning": "Schwebungsoszillator — beat frequency oscillator.",
      "exam": true,
      "explanation": "Reinjects a carrier at the product detector so CW and SSB become audible."
    },
    {
      "code": "LO",
      "category": "Baugruppe",
      "meaning": "Lokaloszillator — local (mixing) oscillator.",
      "exam": false,
      "explanation": "Provides the frequency mixed with the received or transmitted signal. The sum or difference product is selected, for example to convert an amateur band to a fixed intermediate frequency."
    },
    {
      "code": "AGC",
      "category": "Baugruppe",
      "meaning": "automatische Verstärkungsregelung — automatic gain control.",
      "exam": true,
      "explanation": "Holds the receiver output roughly constant across strong and weak signals."
    },
    {
      "code": "ALC",
      "category": "Baugruppe",
      "meaning": "automatische Pegelregelung — automatic level control.",
      "exam": true,
      "explanation": "Limits transmitter drive to prevent overdrive and splatter."
    },
    {
      "code": "PA",
      "category": "Baugruppe",
      "meaning": "Endstufe / Leistungsverstärker — power amplifier.",
      "exam": true,
      "explanation": "The final transmitter stage that raises the RF signal to the required output power. It must be driven within its linear range for SSB and digital modes to avoid splatter and intermodulation."
    },
    {
      "code": "LNA",
      "category": "Baugruppe",
      "meaning": "rauscharmer Vorverstärker — low-noise amplifier.",
      "exam": true,
      "explanation": "A low-noise preamplifier, often at the antenna, to improve weak-signal reception on VHF and up."
    },
    {
      "code": "ATU",
      "category": "Baugruppe",
      "meaning": "Antennenanpassgerät — antenna tuning unit.",
      "exam": false,
      "explanation": "Matches the feed line to the transmitter so the PA sees a low SWR; it does not 'tune' the antenna itself."
    },
    {
      "code": "TRX",
      "category": "Baugruppe",
      "meaning": "Transceiver — combined transmitter and receiver.",
      "exam": true,
      "explanation": "Common shorthand in German amateur-radio diagrams and operating notes for a radio that shares controls and circuitry between transmit and receive."
    },
    {
      "code": "VOX",
      "category": "Baugruppe & Bedienung",
      "meaning": "Voice-Operated Transmit — sprachgesteuerte Sendeumschaltung.",
      "exam": true,
      "explanation": "Switches a transceiver to transmit when microphone audio exceeds a threshold. Set gain, delay and anti-VOX carefully so loudspeaker audio or room noise does not key the transmitter accidentally."
    },
    {
      "code": "Balun",
      "category": "Baugruppe",
      "meaning": "Symmetrierglied — balanced-to-unbalanced transformer.",
      "exam": true,
      "explanation": "Interfaces a balanced load, such as a dipole, with an unbalanced feed line such as coax. Common-mode suppression depends on the balun type: a suitable current balun or choke is needed when feed-line current must be blocked."
    },
    {
      "code": "LED",
      "category": "Bauteil",
      "meaning": "Leuchtdiode — light-emitting diode.",
      "exam": true,
      "explanation": "Emits light when forward biased and requires current limiting. In station equipment it is commonly used for status indication and display backlighting."
    },
    {
      "code": "FET",
      "category": "Bauteil",
      "meaning": "Feldeffekttransistor — field-effect transistor.",
      "exam": true,
      "explanation": "A voltage-controlled transistor with very high input impedance."
    },
    {
      "code": "MOSFET",
      "category": "Bauteil",
      "meaning": "Metall-Oxid-Halbleiter-FET — metal-oxide-semiconductor FET.",
      "exam": true,
      "explanation": "An insulated-gate FET; common in switching and RF power stages."
    },
    {
      "code": "BJT",
      "category": "Bauteil",
      "meaning": "Bipolartransistor — bipolar junction transistor.",
      "exam": false,
      "explanation": "A current-controlled transistor using both electron and hole conduction. NPN and PNP devices are used in switching and amplifier stages."
    },
    {
      "code": "IC",
      "category": "Bauteil",
      "meaning": "integrierter Schaltkreis — integrated circuit.",
      "exam": false,
      "explanation": "Many components and circuit functions fabricated on one semiconductor chip, from simple voltage regulators to complete mixers, synthesizers and processors."
    },
    {
      "code": "NTC",
      "category": "Bauteil",
      "meaning": "Heißleiter — thermistor with a negative temperature coefficient.",
      "exam": true,
      "explanation": "Its resistance falls as temperature rises; used for temperature sensing and inrush limiting."
    },
    {
      "code": "PTC",
      "category": "Bauteil",
      "meaning": "Kaltleiter — thermistor with a positive temperature coefficient.",
      "exam": true,
      "explanation": "Its resistance rises as temperature rises; used as a resettable fuse and for protection."
    },
    {
      "code": "LDR",
      "category": "Bauteil",
      "meaning": "Fotowiderstand — light-dependent resistor.",
      "exam": true,
      "explanation": "Its resistance decreases as illumination increases. It is useful for light sensing but is slower than a photodiode or phototransistor."
    },
    {
      "code": "VDR",
      "category": "Bauteil",
      "meaning": "spannungsabhängiger Widerstand (Varistor) — voltage-dependent resistor.",
      "exam": true,
      "explanation": "Resistance drops sharply above a threshold voltage; clamps surges and protects against overvoltage."
    },

    {
      "code": "dB",
      "category": "Messgröße & Leistung",
      "meaning": "Dezibel — logarithmic ratio.",
      "exam": true,
      "explanation": "For power ratios use 10·log₁₀(P₂/P₁); for voltage or current ratios under the same impedance use 20·log₁₀. +3 dB is about twice the power and +10 dB is ten times. Plain dB is relative, unlike dBm or dBW."
    },
    {
      "code": "dBi",
      "category": "Messgröße & Leistung",
      "meaning": "Gewinn über Isotropstrahler — gain relative to an isotropic radiator.",
      "exam": true,
      "explanation": "An antenna gain reference, not transmitter power. Because a half-wave dipole has about 2.15 dBi gain, a value in dBi is 2.15 dB higher than the same gain stated in dBd."
    },
    {
      "code": "dBd",
      "category": "Messgröße & Leistung",
      "meaning": "Gewinn über Dipol — gain relative to a half-wave dipole.",
      "exam": true,
      "explanation": "0 dBd = 2.15 dBi; the dipole already has 2.15 dBi of gain over isotropic."
    },
    {
      "code": "dBm",
      "category": "Messgröße & Leistung",
      "meaning": "Pegel bezogen auf 1 mW — power level referenced to 1 milliwatt.",
      "exam": true,
      "explanation": "An absolute level: 0 dBm = 1 mW, 30 dBm = 1 W."
    },
    {
      "code": "dBW",
      "category": "Messgröße & Leistung",
      "meaning": "Pegel bezogen auf 1 W — power level referenced to 1 watt.",
      "exam": true,
      "explanation": "An absolute logarithmic power level: 0 dBW = 1 W and 10 dBW = 10 W. To convert dBW to dBm, add 30 dB."
    },
    {
      "code": "SWR",
      "category": "Messgröße & Leistung",
      "meaning": "Stehwellenverhältnis — standing wave ratio.",
      "exam": true,
      "explanation": "Normally the ratio of maximum to minimum RF voltage along a feed line. 1:1 is a perfect match; a higher value indicates a larger reflection, but does not by itself identify whether the antenna, feed line or another component causes the mismatch."
    },
    {
      "code": "ERP",
      "category": "Messgröße & Leistung",
      "meaning": "effektive Strahlungsleistung — effective radiated power.",
      "exam": true,
      "explanation": "Radiated power referenced to a half-wave dipole. In linear units, multiply power delivered to the antenna by antenna gain relative to a dipole; in decibel units, subtract feed losses and add gain in dBd."
    },
    {
      "code": "EIRP",
      "category": "Messgröße & Leistung",
      "meaning": "äquivalente isotrope Strahlungsleistung — equivalent isotropically radiated power.",
      "exam": true,
      "explanation": "Radiated power referenced to an ideal isotropic radiator. For the same station, EIRP is 1.64 times ERP; when both powers are expressed logarithmically, EIRP is 2.15 dB higher."
    },
    {
      "code": "PEP",
      "category": "Messgröße & Leistung",
      "meaning": "Spitzenleistung — peak envelope power.",
      "exam": true,
      "explanation": "The average power over one RF cycle at the peak of the modulation envelope; the standard rating for SSB transmitters."
    },
    {
      "code": "RMS",
      "category": "Messgröße & Leistung",
      "meaning": "Effektivwert — root mean square.",
      "exam": true,
      "explanation": "The equivalent DC value that produces the same heating; for a sine wave it is the peak divided by √2."
    },
    {
      "code": "Q",
      "category": "Messgröße & Leistung",
      "meaning": "Güte — quality factor of a resonant circuit.",
      "exam": true,
      "explanation": "At resonance, Q = 2π times the energy stored divided by the energy lost per cycle; equivalently it is approximately resonant frequency divided by bandwidth. Higher Q gives a narrower response but also a smaller usable bandwidth."
    },
    {
      "code": "SNR",
      "category": "Messgröße & Leistung",
      "meaning": "Signal-Rausch-Verhältnis — signal-to-noise ratio.",
      "exam": true,
      "explanation": "Compares wanted signal power with noise power, normally in dB and for a stated bandwidth. Narrowing the receiver bandwidth reduces admitted noise and can improve readability even though the received carrier power is unchanged."
    },

    {
      "code": "AC",
      "category": "Strom & Spannung",
      "meaning": "Alternating Current — Wechselstrom; also used for alternating voltage.",
      "exam": true,
      "explanation": "Current whose direction changes periodically. Station mains supplies are AC; power supplies rectify and smooth it to provide the DC required by most transceivers."
    },
    {
      "code": "DC",
      "category": "Strom & Spannung",
      "meaning": "Direct Current — Gleichstrom; also used for direct voltage.",
      "exam": true,
      "explanation": "Current with constant polarity. Most mobile amateur equipment is designed for a nominal 13.8 V DC supply, where correct polarity and adequate cable size are essential."
    },

    {
      "code": "MUF",
      "category": "Ausbreitung",
      "meaning": "höchste brauchbare Frequenz — maximum usable frequency.",
      "exam": true,
      "explanation": "The highest frequency that is refracted back to Earth for a specified path and time. Above it, that ionospheric path normally fails; the value changes with distance, solar conditions, season and time of day."
    },
    {
      "code": "LUF",
      "category": "Ausbreitung",
      "meaning": "niedrigste brauchbare Frequenz — lowest usable frequency.",
      "exam": true,
      "explanation": "The lowest frequency that still provides the required signal quality on a specified path. Below it, ionospheric absorption and atmospheric noise usually dominate; it is an operational limit, not a fixed band boundary."
    },
    {
      "code": "NVIS",
      "category": "Ausbreitung",
      "meaning": "Steilstrahlung — near-vertical incidence skywave.",
      "exam": true,
      "explanation": "Uses high-angle HF radiation refracted back to Earth for regional communication, typically on 160, 80, 60 or 40 m depending on conditions. It can cover the skip zone of lower-angle paths, but coverage is never guaranteed."
    },

    {
      "code": "DMR",
      "category": "Digital & Daten",
      "meaning": "Digital Mobile Radio — digitale Sprach- und Datenbetriebsart.",
      "exam": true,
      "explanation": "An ETSI digital mobile-radio standard using two-slot TDMA on a 12.5 kHz carrier. Amateur Tier II operation is common on repeaters and hotspots; talkgroups and timeslots must be selected correctly."
    },
    {
      "code": "D-STAR",
      "category": "Digital & Daten",
      "meaning": "Digital Smart Technologies for Amateur Radio — digital voice and data system.",
      "exam": true,
      "explanation": "An open amateur-radio specification developed through JARL. Callsign routing and reflector linking are common in practice; Icom is a major equipment vendor, not part of the abbreviation."
    },
    {
      "code": "C4FM",
      "category": "Digital & Daten",
      "meaning": "Continuous 4-Level Frequency Modulation — four-level digital modulation.",
      "exam": true,
      "explanation": "Maps dibits to four frequency deviations. Yaesu System Fusion uses C4FM, but the modulation name and the complete network/system are not synonymous."
    },
    {
      "code": "APRS",
      "category": "Digital & Daten",
      "meaning": "Automatic Packet Reporting System — Positions- und Telemetriedaten über Packet.",
      "exam": false,
      "explanation": "Shares position, status, telemetry, messages and objects, commonly as 1200-baud packet on 144.800 MHz in Europe. Use an appropriate path and beacon rate to avoid unnecessary channel congestion."
    },
    {
      "code": "TNC",
      "category": "Digital & Daten",
      "meaning": "Terminal Node Controller — Packet-Radio-Modem.",
      "exam": false,
      "explanation": "Interfaces a computer or terminal with a radio and handles packet framing and modulation. Modern APRS stations often implement the same functions in software."
    },
    {
      "code": "AX.25",
      "category": "Digital & Daten",
      "meaning": "Amateurfunk-Datenprotokoll — amateur packet-radio link protocol.",
      "exam": false,
      "explanation": "Amateur adaptation of X.25 used for packet radio and APRS frames. It carries amateur callsigns in the link-layer addresses and can support connected or unconnected operation."
    },
    {
      "code": "CTCSS",
      "category": "Signalisierung & Bedienung",
      "meaning": "Continuous Tone-Coded Squelch System — subaudible tone squelch.",
      "exam": false,
      "explanation": "A continuous low audio-frequency tone, typically 67 to 254 Hz, that allows a repeater or receiver to open only for the selected tone. 'Subaudible' means it is normally filtered from the loudspeaker audio, not that it lies below the human hearing range."
    },
    {
      "code": "DTMF",
      "category": "Signalisierung & Bedienung",
      "meaning": "Dual-Tone Multi-Frequency — Mehrfrequenzwahlverfahren.",
      "exam": false,
      "explanation": "Each key sends one tone from a low group and one from a high group. Amateur stations use it mainly for repeater control, link commands and legacy telephone interconnects."
    },
    {
      "code": "DCS",
      "category": "Signalisierung & Bedienung",
      "meaning": "Digital-Coded Squelch — digitale Rauschsperrencodierung.",
      "exam": false,
      "explanation": "Sends a continuous low-rate digital code with analogue FM so a receiver opens only for the selected code. It serves a similar access-filtering purpose to CTCSS but is not a digital voice mode."
    },
    {
      "code": "PTT",
      "category": "Baugruppe & Bedienung",
      "meaning": "Push To Talk — Sendetaste.",
      "exam": true,
      "explanation": "Keys the transmitter while pressed. Confirm that the frequency is clear before using it, and allow a brief pause after keying a repeater so the first syllable is not clipped."
    },
    {
      "code": "SDR",
      "category": "Digital & Daten",
      "meaning": "Software Defined Radio — softwaredefiniertes Funkgerät.",
      "exam": true,
      "explanation": "Implements functions such as mixing, filtering and demodulation in software or programmable logic. An SDR still needs suitable analogue RF filtering, gain control and conversion hardware."
    },
    {
      "code": "RIT",
      "category": "Baugruppe & Bedienung",
      "meaning": "Receiver Incremental Tuning — Empfänger-Feinverstimmung.",
      "exam": true,
      "explanation": "Shifts only the receive frequency while leaving transmit frequency unchanged. It is useful when the other station is slightly off frequency; reset it afterward to avoid later tuning confusion."
    },

    {
      "code": "ITU",
      "category": "Organisation & Vorschrift",
      "meaning": "Internationale Fernmeldeunion — International Telecommunication Union.",
      "exam": true,
      "explanation": "UN agency that allocates spectrum worldwide and defines the three ITU regions."
    },
    {
      "code": "IARU",
      "category": "Organisation & Vorschrift",
      "meaning": "Internationale Amateur-Radio-Union — International Amateur Radio Union.",
      "exam": true,
      "explanation": "Worldwide federation of national amateur-radio societies; coordinates band plans and represents amateurs at the ITU."
    },
    {
      "code": "CEPT",
      "category": "Organisation & Vorschrift",
      "meaning": "Europäische Konferenz der Verwaltungen für Post und Telekommunikation.",
      "exam": true,
      "explanation": "Its recommendations let an amateur licensee operate temporarily in other member countries without applying for a separate licence."
    },
    {
      "code": "BNetzA",
      "category": "Organisation & Vorschrift",
      "meaning": "Bundesnetzagentur — the German telecommunications regulator.",
      "exam": true,
      "explanation": "Issues amateur licences and call signs in Germany and supervises the service."
    },
    {
      "code": "EMV",
      "category": "Organisation & Vorschrift",
      "meaning": "elektromagnetische Verträglichkeit — electromagnetic compatibility (EMC).",
      "exam": true,
      "explanation": "The ability of equipment to operate without causing or suffering undue interference."
    },
    {
      "code": "EMVU",
      "category": "Organisation & Vorschrift",
      "meaning": "elektromagnetische Umweltverträglichkeit — EMF exposure compliance.",
      "exam": true,
      "explanation": "Assessment and limits for human exposure to the electromagnetic fields a station produces."
    },
    {
      "code": "AFu",
      "category": "Organisation & Vorschrift",
      "meaning": "Amateurfunk — amateur radio.",
      "exam": false,
      "explanation": "Common German written abbreviation in terms such as AFuG and AFuV. It is mainly documentation shorthand rather than something spoken during a contact."
    }
  ]
}