Low Frequency (LF)

Click the name of a signal to see more detailed information, possible decoding, and additional sound and waterfall samples

Signal Name	Description	Frequency	Mode	Modulation	Bandwidth	Location	Sample Audio	Waterfall image
Accurate positioning by Low Frequencies (ALF)	Accurate positioning by Low Frequencies, a former German DGPS navigation system. No longer in use as of 2013.	123.7 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	PSKPhase-Shift Keying	2.1 kHzKiloHertz (kHz) 10^3 Hz	Germany
Amplitude Modulation (AM)	Long range commercial broadcast and international radio. Also used for aviation communications.	153 kHzKiloHertz (kHz) 10^3 Hz — 137 MHzMegaHertz (MHz) 10^6 Hz	AMAmplitude Modulation	AMAmplitude Modulation	10 kHzKiloHertz (kHz) 10^3 Hz	Worldwide
Amplitude Modulation Signalling System (AMSS)	Amplitude Modulation Signalling System (AMSS) is a DRM-based radiotext and data technology for AMAmplitude Modulation broadcasting, like RDS that is used for FMFrequency Modulation. It transmits as a subcarrier, phase-modulating the carrier frequency.	100 kHzKiloHertz (kHz) 10^3 Hz — 30 MHzMegaHertz (MHz) 10^6 Hz	SSBSingle-sideband modulation	AMAmplitude Modulation, PSKPhase-Shift Keying	200 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
BPC	BPC is the callsign of the Chinese low-frequency time broadcasting station, located near Shangqiu, Henan in China.	68.5 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	AMAmplitude Modulation	1 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	China
Coherent BPSK	Coherent BPSKBinary Phase-Shift Keying (1 bit per symbol), also known as C-BPSKBinary Phase-Shift Keying (1 bit per symbol), was an experimental amateur mode developed by Bill DeCarle VE2IQ.	138 kHzKiloHertz (kHz) 10^3 Hz — 18.081 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	PSKPhase-Shift Keying	200 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
DCF77	DCF77 is a German longwave time signal radio station based at 77.5 kHzKiloHertz (kHz) 10^3 Hz. DCF uses an AMAmplitude Modulation modulated carrier and phase modulation sidebands to transmit its time signal.	77.5 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	AMAmplitude Modulation, PSKPhase-Shift Keying	1.3 kHzKiloHertz (kHz) 10^3 Hz	Germany
Differential Global Positioning System (DGPS)	Differential GPS (DGPS), also known as M823 DGPS and SC-104 DGPS, is a supplementary correction signal used by GPS receivers to increase the accuracy of GPS based positioning.	283.5 kHzKiloHertz (kHz) 10^3 Hz — 2.95 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	MSKMinimum-Shift Keying (When Shift/Bd = 0.5. It is impossible to get this ratio to be lower than 0.5, hence it is called the 'Minimum' shift.)	150 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). — 250 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
EFR Teleswitch	Europäische Funk-Rundsteuerung (EFR) Teleswitch (European Radio Ripple Control GmbH (ERA) Teleswitch) is an energy management system operated via long-wave radio. Uses two transmitters in Germany and one in Hungary. Also known by DCF39, DCF49 and HGA22.	129.1 kHzKiloHertz (kHz) 10^3 Hz — 139.9 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	FSKFrequency-Shift Keying	1 kHzKiloHertz (kHz) 10^3 Hz	Europe
FST4W	FST4W is an amateur radio digital protocol designed particularly for the LFLow Frequency (30-300 kHz) and MFMedium Frequency (300-3000 kHz) bands, for quasi-beacon transmissions of WSPR-style messages. FST4W uses 4-GFSKGaussian Frequency-Shift Keying modulation and offers T/R sequence lengths of 120, 300, 900, and 1800 seconds.	136 kHzKiloHertz (kHz) 10^3 Hz — 1.839 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	4-GFSKGaussian Frequency-Shift Keying		Worldwide	—
GYN2 GBR	Transmitting site owned by the Ministry of Defense. Originally constructed in 1946 and was originally used as a shortwave radio station. In present time, the transmitting site is used by the British Navy in order to transmit encrypted messages to submarines at sea. The site is also capable of DRM and is beamed at 121°, towards Germany and Central Europe	81 kHzKiloHertz (kHz) 10^3 Hz				United Kingdom
Induction cooker interference	RFRadio Frequency interference from nearby induction cooker can sometimes be mistaken for a real LFLow Frequency (30-300 kHz) or VLFVery Low Frequency (3-30 kHz) transmission.		USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	OOKOn-Off Keying Modulation		Worldwide
JJY	JJY, also known as JJY-40 and JJY-60, is the call sign for a pair of longwave Time Signal stations in Japan.	40 kHzKiloHertz (kHz) 10^3 Hz — 60 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	AMAmplitude Modulation	1 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Japan
LORAN	LORAN (short for LOng RAnge Navigation) is a hyperbolic radio navigation system.	100 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	PPMPulse Position Modulation	20 kHzKiloHertz (kHz) 10^3 Hz	Worldwide
Lentus	Lentus is an extremely slow QRPIn amateur radio, QRP operation refers to transmitting at reduced power while attempting to maximize one's effective range. mode developed by Patrick Lindecker F6CTE used to transmit QRPIn amateur radio, QRP operation refers to transmitting at reduced power while attempting to maximize one's effective range.'s at very low power. Each 43-character (75 bit) transmission takes roughly 5 minutes to transmit across 32 possible tones in a tight 25 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). bandwidth.	136.3 kHzKiloHertz (kHz) 10^3 Hz — 14.096 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	MFSKMultiple Frequency Shift-Keying	25 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
MSF	MSF is a time signal station in Anthorn, United Kingdom, which broadcasts the UK national time reference	60 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	OOKOn-Off Keying Modulation	5 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	United Kingdom, Europe
Morse Code (CW)	CWContinuous Wave Morse Code is the simplest form of transmission found virtually all over the RFRadio Frequency bands for a variety of uses. The most common use of this is for Call-sign Beacons by both Amateur and Military operators.	3 kHzKiloHertz (kHz) 10^3 Hz — 250,000 MHzMegaHertz (MHz) 10^6 Hz	CWContinuous Wave	OOKOn-Off Keying Modulation		Worldwide
Non-Directional Beacon (NDB)	A Non-Directional Beacon (NDB) is a ground-based, low frequency radio transmitter used as an instrument approach for airports and offshore platforms.	190 kHzKiloHertz (kHz) 10^3 Hz — 1.8 MHzMegaHertz (MHz) 10^6 Hz	CWContinuous Wave	A2A (AMAmplitude Modulation)	2 kHzKiloHertz (kHz) 10^3 Hz	Worldwide
PI4	PI4 (PharusIgnis4) is a 4-MFSKMultiple Frequency Shift-Keying mode designed for amateur radio beacons. It is designed to work via different propagation modes.	136 kHzKiloHertz (kHz) 10^3 Hz — 10,000 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	MFSKMultiple Frequency Shift-Keying	709 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
RBU	RBU is a time code radio station located in Moscow. It transmits a continuous 10 kW time code on 66.66 kHzKiloHertz (kHz) 10^3 Hz.	66.66 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	FSKFrequency-Shift Keying	650 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Russia
Radio Teletype (RTTY)	RTTYRadio TeleTYpe (Also known as Baudot or ITA2) uses the Baudot 5-bit alphabet with FSKFrequency-Shift Keying to send text messages over the shortwave. This mode is gradually dying out in favor of more robust modes like PSK31 in the amateur service.	147.3 kHzKiloHertz (kHz) 10^3 Hz — 28.15 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	FSKFrequency-Shift Keying	85 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). — 850 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
Russian overhead power line telemetry system	Russian telemetry system, transmitted over the overhead power lines.	50 kHzKiloHertz (kHz) 10^3 Hz — 1 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	FSKFrequency-Shift Keying	400 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Russia
SAS/SRC	Swedish navy transmitter for submarine communication. It shares the antenna with SAQ (Grimeton Radio)	40.4 kHzKiloHertz (kHz) 10^3 Hz		MSKMinimum-Shift Keying (When Shift/Bd = 0.5. It is impossible to get this ratio to be lower than 0.5, hence it is called the 'Minimum' shift.)		Sweden
SAS2	Swedish navy transmitter for submarine communication. It shares the antenna with SAQ (Grimeton Radio) and is activated less often as the other Swedish transmitters used for VLFVery Low Frequency (3-30 kHz) submarine communication. Usually, it works with reduced power.	42.5 kHzKiloHertz (kHz) 10^3 Hz		MSKMinimum-Shift Keying (When Shift/Bd = 0.5. It is impossible to get this ratio to be lower than 0.5, hence it is called the 'Minimum' shift.)		Sweden
SAS3	Swedish navy transmitter for submarine communication. It shares the antenna with SAQ (Grimeton Radio).	44.2 kHzKiloHertz (kHz) 10^3 Hz		MSKMinimum-Shift Keying (When Shift/Bd = 0.5. It is impossible to get this ratio to be lower than 0.5, hence it is called the 'Minimum' shift.)		Sweden
SHR	Swedish navy transmitter for submarine communication. It shares the antenna with SAQ (Grimeton Radio).	38 kHzKiloHertz (kHz) 10^3 Hz		MSKMinimum-Shift Keying (When Shift/Bd = 0.5. It is impossible to get this ratio to be lower than 0.5, hence it is called the 'Minimum' shift.)		Sweden
STANAG 5065	STANAGNATO Standardization Agreement (STANAG), defines processes, procedures, terms, and conditions for common military or technical procedures or equipment between the member countries of the North Atlantic Treaty Organization (NATO). 5065 is defined as "Minimum Standards for Naval Low Frequency (LFLow Frequency (30-300 kHz)) Shore-To-Ship Surface Broadcast Systems", with two primary protocols, FSK75 and MSK300.	50 kHzKiloHertz (kHz) 10^3 Hz — 160 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	FSKFrequency-Shift Keying, MSKMinimum-Shift Keying (When Shift/Bd = 0.5. It is impossible to get this ratio to be lower than 0.5, hence it is called the 'Minimum' shift.)	235 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). — 360 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
Single frequency russian overhead power line telemetry system	Russian telemetry system, transmitted over the overhead power lines.	50 kHzKiloHertz (kHz) 10^3 Hz — 1 MHzMegaHertz (MHz) 10^6 Hz	SSBSingle-sideband modulation	AMAmplitude Modulation	300 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Russia
Sonne	Sonne (Called Consol by the Britons) was a low-frequency radio range based radio navigation system used for long range navigation.	250 kHzKiloHertz (kHz) 10^3 Hz — 350 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	OOKOn-Off Keying Modulation	1 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
Switch-mode power supply interference	Switch-mode power supplies, used in many types of electronic devices, can generate RFRadio Frequency noise on wide frequency ranges.	10 kHzKiloHertz (kHz) 10^3 Hz — 200 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)			Worldwide
TDF	TDF, also known as ALS162, is a time signal transmitted on the former carrier of France's France Inter longwave AMAmplitude Modulation radio station on 162 kHzKiloHertz (kHz) 10^3 Hz.	162 kHzKiloHertz (kHz) 10^3 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	PSKPhase-Shift Keying	1 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	France
UK AM Data System (UK-AMDS)	UK AMAmplitude Modulation Data System (UK-AMDS) was developed by BBC Research and Development in 1984 as a way to transmit low bitrate data on BBC Radio 4's LFLow Frequency (30-300 kHz) AMAmplitude Modulation carrier. Elements of this system were adopted into ETSIEuropean Telecommunications Standards Institute. An independent, not-for-profit, standardization organization in the telecommunications industry in Europe, developing global telecommunications standards.'s AMSS.	198 kHzKiloHertz (kHz) 10^3 Hz	SSBSingle-sideband modulation	AMAmplitude Modulation, PSKPhase-Shift Keying	85 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	United Kingdom
WSPR	Weak Signal Propagation Reporter.	136 kHzKiloHertz (kHz) 10^3 Hz — 1,296.5 MHzMegaHertz (MHz) 10^6 Hz	USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)	MFSKMultiple Frequency Shift-Keying	6 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	Worldwide
WWVB	WWVB is the lowest frequency time signal in the USA.	60 kHzKiloHertz (kHz) 10^3 Hz	CWContinuous Wave	AMAmplitude Modulation	1 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).	United States