Reference
Glossary
Short explanations of the radio words used in the app and in these pages.
- AGC
- Automatic gain control. Keeps the volume even when a signal gets stronger or weaker. Fast, Medium and Slow set how quickly it reacts.
- Bias-T
- A 5 V supply sent up the antenna cable to power an LNA or an active antenna.
- CW
- Continuous wave: Morse code sent by switching a carrier on and off. You hear it as beeps.
- De-emphasis
- Broadcast FM boosts the high tones before it is sent. De-emphasis lowers them again at the receiver. It is 50 µs in Europe and 75 µs in the Americas.
- LNA
- Low-noise amplifier. A small amplifier next to the antenna that helps weak signals.
- NFM, WFM
- Narrow FM (a channel about 12.5 kHz wide, used for walkie-talkies, marine and amateur radio) and wide FM (about 180 kHz, broadcast radio).
- Notch
- A very narrow filter that removes one frequency, such as a whistle.
- ppm
- Parts per million. How much a stick's clock is off. Fix it with the frequency correction.
- RDS
- The data sent with a broadcast FM station: its name and a line of text.
- rtl_tcp
- A way to share an RTL-SDR over the network. A computer with a stick runs it; SDRSowa on your phone connects to it.
- SAM
- Synchronous AM. AM with a detector locked to the carrier, which sounds steadier when the signal fades.
- SNR
- Signal-to-noise ratio, in dB. How far the signal stands over the noise. More is better.
- Spectrum, waterfall
- The spectrum shows how strong signals are at each frequency. The waterfall shows the same over time, newest at the top.
- SSB (USB, LSB)
- Single sideband. A voice mode used by radio amateurs and on shortwave. USB is the upper sideband, LSB the lower one.
- Squelch
- Keeps the speaker quiet until a signal is strong enough.
- VFO
- Variable frequency oscillator. In the scanner, one VFO is one channel you hear. SDRSowa can hold up to 3 at the same time.