Radio terms
These definitions are sufficient for following the operating guides. The linked pages contain the technical detail.
| Term | Meaning in SimTX | Read more |
|---|---|---|
| TX / RX | Transmit / receive. A transmitter sends a signal; a receiver tunes to it. | SimTX Transmitter |
| Server | The shared simulation to which transmitters and receivers connect. Both must use the same server to share signals. | Getting Started |
| Callsign | The station name shown with a transmission. It is not the account sign-in. | Station Configuration |
| Frequency | Where the signal is placed on the radio dial. 1000 Hz = 1 kHz; 1000 kHz = 1 MHz. 4625000 Hz = 4625 kHz = 4.625 MHz. | Modulation Modes |
| Modulation | How information is carried by a radio signal. The receiver needs a compatible mode, such as AM or USB. | Modulation Modes |
| Bandwidth | How wide a signal or receiver channel is, measured in Hz. It is different from the centre frequency and the sample rate. | Modulation Modes |
| Power (W) | Requested transmitter output in watts. Actual output can fall because of antenna mismatch or heating. | Power Amplifier Behaviour |
| Audio gain | The level of the audio fed into the transmitter. It is not the same control as radio output power. | Transmission Sources |
| Antenna | The simulated structure that radiates or receives the signal. Its size and orientation affect reception. | Antenna System |
| SWR / VSWR | A measure of antenna matching. Closer to 1 means less reflected power; it does not measure distance or audio quality. | SWR and Transmitter Protection |
| FWD / REF | Forward power leaving the transmitter / power reflected by the antenna mismatch. | Transmitter Interface |
| PA / ALC | Power amplifier / automatic level control. These describe output-stage behavior, not separate audio sources. | Advanced Transmitter Settings |
| dB / dBi | Decibels express ratios. dBi expresses antenna gain relative to an ideal reference in a direction. | Antenna Calculations |
| Azimuth | A compass direction: 0° north, 90° east, 180° south, 270° west. | Antenna System |
| Propagation | How the signal travels from transmitter to receiver, including ground and ionospheric paths. | Propagation Basics |
| IQ | Two components of a complex signal. External IQ already describes a radio waveform, rather than ordinary sound for AM or FM to encode. | Transmission Sources |
| Session | One transmission with its own state and controls. Pressing Start TX creates a new session. | Sessions and Queueing |
| Lua extension | An installed package that adds features. Using one does not require programming. | Lua extensions |
| API / manifest | An API defines functions available to extension code. A manifest describes a package and its requirements. | Creating Lua extensions |