Signal Identification Guide

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This wiki is intended to help identify radio signals through example sounds and waterfall images. Most signals are received and recorded using a software defined radio such as the RTL-SDR, HackRF, BladeRF, Funcube Dongle, USRP or others.

Anyone can edit this wiki, so if you see missing or wrong information please feel free to correct it by clicking the 'edit' button at the stop of the signals page. When doing an edit you will be asked to answer a very simple spam prevention question which will appear at the top of the screen after clicking on Save page.

You can also discuss the signals by using the discussion tab at the top of every page, or just by using the comments box at the bottom of this page.

If you would like to contribute an example signal, please contact me at rtlsdrblog__AT__gmail__DOT__com and send a waterfall image, sound or small IQ sample and any information about the signal that you have. If you want to add a signal yourself please consult the instructions here - Adding An Example Signal.

Known Reference Signals

Signal Type Description Frequency Mode Bandwidth Location Sample Audio Waterfall Image
AFSK Paging Link It is easier to transmit the FSK pager signal to the transmitter site as AFSK. It is changed to POCSAG format when re-transmitted. 72 MHz72,000,000 Hz
72,000 kHz
, 75 MHz75,000,000 Hz
75,000 kHz
NFM 9,000 Hz9 kHz
0.009 MHz
Worldwide AFSKPaging Waterfall.png
AMTOR/SITOR SITOR stands for Simplex Teletype Over Radio. Usually used to transmit maritime short messages, weather forecasts and warnings. AMTOR is the same but is used by amateur radio operators. 3 MHz3,000,000 Hz
3,000 kHz
USB 0 Hz0 kHz
0 MHz
Worldwide NO Waterfall.jpg
Aircraft Communications Addressing and Reporting System (ACARS) Short messages sent to and from aircraft. 129.125 MHz129,125,000 Hz
129,125 kHz
, 130.45 MHz130,450,000 Hz
130,450 kHz
, 131.125 MHz131,125,000 Hz
131,125 kHz
, 131.45 MHz131,450,000 Hz
131,450 kHz
, 131.475 MHz131,475,000 Hz
131,475 kHz
, 131.725 MHz131,725,000 Hz
131,725 kHz
, 136.7 MHz136,700,000 Hz
136,700 kHz
, 136.9 MHz136,900,000 Hz
136,900 kHz
, 136.85 MHz136,850,000 Hz
136,850 kHz
, 136.75 MHz136,750,000 Hz
136,750 kHz
, 131.85 MHz131,850,000 Hz
131,850 kHz
, 131.55 MHz131,550,000 Hz
131,550 kHz
, 130.025 MHz130,025,000 Hz
130,025 kHz
, 130.425 MHz130,425,000 Hz
130,425 kHz
, 131.525 MHz131,525,000 Hz
131,525 kHz
, 136.8 MHz136,800,000 Hz
136,800 kHz
AM 5,000 Hz5 kHz
0.005 MHz
Worldwide ACARS waterfall.png
Amplitude Modulation (AM) Long range commercial broadcast and international radio. Also used for aviation communications. 0.153 MHz153,000 Hz
153 kHz
, 0.279 MHz279,000 Hz
279 kHz
, 0.531 MHz531,000 Hz
531 kHz
, 1.611 MHz1,611,000 Hz
1,611 kHz
, 0.54 MHz540,000 Hz
540 kHz
, 1.61 MHz1,610,000 Hz
1,610 kHz
, 2.3 MHz2,300,000 Hz
2,300 kHz
, 108 MHz108,000,000 Hz
108,000 kHz
, 137 MHz137,000,000 Hz
137,000 kHz
, 26.1 MHz26,100,000 Hz
26,100 kHz
AM 10,000 Hz10 kHz
0.01 MHz
Worldwide AM Waterfall.jpg
Autocab This is an example of the Autocab Media Data Terminals used by cab companies all over the world. Also this could be the answer for unknown signal Unknown 469. 163.375 MHz163,375,000 Hz
163,375 kHz
NFM 12,500,000 Hz12,500 kHz
12.5 MHz
UK Autocab.png
Automatic Dependent Surveillance-Broadcast (ADS-B) Used by aircraft as an artificial radar. Broadcasts their latitude, longitude and altitude from GPS information. 1,090 MHz1,090,000,000 Hz
1,090,000 kHz
, 978 MHz978,000,000 Hz
978,000 kHz
None 50,000 Hz50 kHz
0.05 MHz
, 1,300,000 Hz1,300 kHz
1.3 MHz
Worldwide ADSB Waterfall.png
Automatic Identification System (AIS) Used by ships to broadcast position and vessel information. 161.975 MHz161,975,000 Hz
161,975 kHz
, 162.025 MHz162,025,000 Hz
162,025 kHz
NFM 25,000 Hz25 kHz
0.025 MHz
Worldwide AIS Waterfall.jpg
Automatic Packet Reporting System (APRS) Packet system for real time data communications. Used by hams for location reporting, weather stations etc. 144.39 MHz144,390,000 Hz
144,390 kHz
, 144.575 MHz144,575,000 Hz
144,575 kHz
, 144.66 MHz144,660,000 Hz
144,660 kHz
, 144.93 MHz144,930,000 Hz
144,930 kHz
, 145.57 MHz145,570,000 Hz
145,570 kHz
, 145.525 MHz145,525,000 Hz
145,525 kHz
, 144.8 MHz144,800,000 Hz
144,800 kHz
, 145.175 MHz145,175,000 Hz
145,175 kHz
NFM 10,000 Hz10 kHz
0.01 MHz
Worldwide AFSK1200 Waterfall.png
Automatic Picture Transmission (APT) Used to by the NOAA weather satellites and some Russian weather satellites to transmit satellite weather photos. 137.62 MHz137,620,000 Hz
137,620 kHz
, 137.913 MHz137,912,500 Hz
137,912.5 kHz
, 137.1 MHz137,100,000 Hz
137,100 kHz
, 137.85 MHz137,850,000 Hz
137,850 kHz
, 137.3 MHz137,300,000 Hz
137,300 kHz
NFM 30,000 Hz30 kHz
0.03 MHz
Worldwide NOAAAPT Waterfall.png
Baby Monitor Wireless baby monitors often transmit NFM audio in the clear. 40 MHz40,000,000 Hz
40,000 kHz
, 49.5 MHz49,500,000 Hz
49,500 kHz
, 50 MHz50,000,000 Hz
50,000 kHz
, 27 MHz27,000,000 Hz
27,000 kHz
, 864 MHz864,000,000 Hz
864,000 kHz
NFM 15,000 Hz15 kHz
0.015 MHz
Worldwide No Audio File BabyMonitor Waterfall.png
Binary Phase Shift Keying (BPSK31) A digital amateur radio mode based on Phase Shift Keying (PSK) modulation. 7.035 MHz7,035,000 Hz
7,035 kHz
, 7.04 MHz7,040,000 Hz
7,040 kHz
, 10.142 MHz10,142,000 Hz
10,142 kHz
, 14.07 MHz14,070,000 Hz
14,070 kHz
, 21.08 MHz21,080,000 Hz
21,080 kHz
, 50.29 MHz50,290,000 Hz
50,290 kHz
, 144.144 MHz144,144,000 Hz
144,144 kHz
, 222.07 MHz222,070,000 Hz
222,070 kHz
, 432.2 MHz432,200,000 Hz
432,200 kHz
, 909 MHz909,000,000 Hz
909,000 kHz
, 1.838 MHz1,838,000 Hz
1,838 kHz
, 3.58 MHz3,580,000 Hz
3,580 kHz
, 18.1 MHz18,100,000 Hz
18,100 kHz
, 24.92 MHz24,920,000 Hz
24,920 kHz
, 28.12 MHz28,120,000 Hz
28,120 kHz
SSB 31 Hz0.031 kHz
3.1e-5 MHz
Worldwide BPSK31 Waterfall.png
Cuban Numbers Station HM01 Numbers stations are thought to transmit encoded information for various spy agencies around the world. They are recognized by a voice reading a sequence of numbers or words. This is a Cuban Numbers Station which has a data portion and a voice portion. 11.53 MHz11,530,000 Hz
11,530 kHz
, 16.18 MHz16,180,000 Hz
16,180 kHz
, 9.24 MHz9,240,000 Hz
9,240 kHz
AM 10,000 Hz10 kHz
0.01 MHz
Worldwide HM01 Waterfall.png
D-STAR Digital voice protocol used by ham radio. Is sometimes routed over the internet for international communications. 145.67 MHz145,670,000 Hz
145,670 kHz
NFM 6,250 Hz6.25 kHz
0.00625 MHz
Worldwide DStar Waterfall.jpg
Digital Audio Broadcasting (DAB) A type of digital broadcast radio signal, containing multiple digital radio stations in the signal. 239.2 MHz239,200,000 Hz
239,200 kHz
, 174.928 MHz174,928,000 Hz
174,928 kHz
, 1,452.96 MHz1,452,960,000 Hz
1,452,960 kHz
, 1,490.625 MHz1,490,625,000 Hz
1,490,625 kHz
None 1,537,000 Hz1,537 kHz
1.537 MHz
Worldwide No Audio File DAB Waterfall.jpg
Digital Audio Broadcasting + (DAB+) A type of digital broadcast radio signal, containing multiple digital radio stations in the signal. Here transmitted on channel 7D. 194.064 MHz194,064,000 Hz
194,064 kHz
None 1,500,000 Hz1,500 kHz
1.5 MHz
Switzerland No Audio File 193MHz Waterfall.png
Digital Radio Mondiale (DRM) A form of international digital shortwave radio. A digital alternative to AM shortwave radio. 1 MHz1,000,000 Hz
1,000 kHz
, 22 MHz22,000,000 Hz
22,000 kHz
USB 10,000 Hz10 kHz
0.01 MHz
Worldwide DRM Waterfall.png
Distributed Power Unit (DPU) Distributed power refers to the placing of an extra locomotive at an intermediate point in the middle section of a train. This locomotive unit is remotely controlled from the lead locomotive, and greatly increases both the pulling and stopping power of longer trains. 457.925 MHz457,925,000 Hz
457,925 kHz
NFM 0 Hz0 kHz
0 MHz
Seattle Distributed Power Unit (DPU).png
EDACS96 Radio trunking control channel. 860 MHz860,000,000 Hz
860,000 kHz
NFM 10,000 Hz10 kHz
0.01 MHz
Worldwide EDACS96 Waterfall.png
Emergency Action Message (EAM) This is a system used by the US Military to direct nuclear capable forces to execute an operation. This sound file was recorded at 11.175 KHz (Female Voice, Mainsail to Skyking) on 05-20-14 at 0035 UTC. 0.0112 MHz11,175 Hz
11.175 kHz
USB 0 Hz0 kHz
0 MHz
Seattle EAM Waterfall.png
End of Train (EOT) Transmits train telemetry such as brake status and accidental seperation information to the head locomotive. 457.938 MHz457,937,500 Hz
457,937.5 kHz
NFM 0 Hz0 kHz
0 MHz
Seattle EOT Waterfall.png
European Radio Messaging System (ERMES) A European radio paging system. 169 MHz169,000,000 Hz
169,000 kHz
NFM 0 Hz0 kHz
0 MHz
Europe Ermes desktop.jpg
FLEX Pager digital signal. 169 MHz169,000,000 Hz
169,000 kHz
NFM 5,000 Hz5 kHz
0.005 MHz
Worldwide Flex1600bps2level.png
FUNcube-1 Telemetry The Funcube-1 is a Cubesat amateur radio satellite. 145.935 MHz145,935,000 Hz
145,935 kHz
USB 2,000 Hz2 kHz
0.002 MHz
Worldwide Funcube1 Waterfall.jpg
GSM Downlink (Non-Hopping) GSM Cell Phone Downlink (Non Hopping Signal). Audio sample used NFM mode. 900 MHz900,000,000 Hz
900,000 kHz
, 450 MHz450,000,000 Hz
450,000 kHz
, 850 MHz850,000,000 Hz
850,000 kHz
, 1,800 MHz1,800,000,000 Hz
1,800,000 kHz
None 200,000 Hz200 kHz
0.2 MHz
Worldwide GSMNonHopping Waterfall.png
GSM Hopping GSM hopping cell phone signal. 900 MHz900,000,000 Hz
900,000 kHz
, 450 MHz450,000,000 Hz
450,000 kHz
, 850 MHz850,000,000 Hz
850,000 kHz
, 1,800 MHz1,800,000,000 Hz
1,800,000 kHz
None 200,000 Hz200 kHz
0.2 MHz
Worldwide No Audio File GSMHopping Waterfall.jpg
GSM Uplink Initial GSM connection sent from a cell phone. 900 MHz900,000,000 Hz
900,000 kHz
, 450 MHz450,000,000 Hz
450,000 kHz
, 850 MHz850,000,000 Hz
850,000 kHz
, 1,800 MHz1,800,000,000 Hz
1,800,000 kHz
None 200,000 Hz200 kHz
0.2 MHz
Worldwide No Audio File GSMUplink Waterfall.png
High Frequency Data Link (HFDL) An Aircraft Communications Addressing and Reporting System (ACARS) data link that aircraft use to communicate short messages over long distances using HF signals. 2.9 MHz2,900,000 Hz
2,900 kHz
, 22 MHz22,000,000 Hz
22,000 kHz
USB 2,800 Hz2.8 kHz
0.0028 MHz
Worldwide HFDL Waterfall.png
ILS Marker Beacon Used by aircraft for Instrument Landing Systems, transmitted by an upward-facing directive antenna at known distances along the approach path. There are three types of marker beacon: Outer Marker (400 Hz dashes), Middle Marker (1020 Hz dot-dashes), Inner Marker (3000 Hz dots). The latter is installed only in ILSs having decision heights of less than 200 feet (60 m). If the Outer Marker is combined with a NDB (Non Directional Beacon), the two make a "Locator Outer Marker", or LOM. They trigger a three-lights indicator and a togglable aural warning in the cockpit when the aircraft flies directly over them. 75 MHz75,000,000 Hz
75,000 kHz
AM 3,000 Hz3 kHz
0.003 MHz
Worldwide LOM Waterfall.png
ISM Band Power Meter A wireless electricity power monitor. 433 MHz433,000,000 Hz
433,000 kHz
AM 20,000 Hz20 kHz
0.02 MHz
Worldwide ISMBandPowerMeter Waterfall.png
Integrated Digital Enhanced Network (IDEN) A technology developed by Motorola. It is a type of trunked radio with cellular phone benefits. 154.463 MHz154,463,000 Hz
154,463 kHz
NFM 18,540 Hz18.54 kHz
0.0185 MHz
Worldwide No Audio File IDEN Waterfall.jpg
Japanese Slot Machine (XSL) Known as the Japanese Slot Machine. Thought to be data originating from the Japanese Navy. 3 MHz3,000,000 Hz
3,000 kHz
, 9 MHz9,000,000 Hz
9,000 kHz
USB? 2,000 Hz2 kHz
0.002 MHz
Worldwide JSM Waterfall.png
LoJack LoJack is a vehicle tracking system that allows vehicles to be tracked by police, with the aim of recovering them in case of theft via a small radio transceiver clandestinely installed in a vehicle 173.075 MHz173,075,000 Hz
173,075 kHz
USB 0 Hz0 kHz
0 MHz
Seattle LoJack Signal.png
Logic Trunked Radio Control Control channel for a logic trunked radio system. 164.3 MHz164,300,000 Hz
164,300 kHz
NFM 0 Hz0 kHz
0 MHz
Austria LogicTrunkedRadio Waterfall.jpg
MOBITEX A packet-switched data network used often by public safety.  ???  ??? NO Waterfall.jpg
MPT1327 Radio trunking control channel. 420 MHz420,000,000 Hz
420,000 kHz
NFM 10,000 Hz10 kHz
0.01 MHz
Worldwide MPT1327 Waterfall.png
MotoTRBO Motorola digital voice protocol. 860 MHz860,000,000 Hz
860,000 kHz
NFM 10,000 Hz10 kHz
0.01 MHz
Worldwide DMRMOTOTRBO Waterfall.png
Motorola 2F1D Radio trunking control channel. 860 MHz860,000,000 Hz
860,000 kHz
NFM 8,000 Hz8 kHz
0.008 MHz
Worldwide Motorola2F1D Waterfall.png
Nexedge NXDN Trunking Radio trunking control channel. 171.3 MHz171,300,000 Hz
171,300 kHz
NFM 8,000 Hz8 kHz
0.008 MHz
Worldwide NXDNTrunking Waterfall.png
Nissan Car Key Wireless entry rolling code car key. 315 MHz315,000,000 Hz
315,000 kHz
, 433 MHz433,000,000 Hz
433,000 kHz
AM/FM 40,000 Hz40 kHz
0.04 MHz
Worldwide NissanCarFob Waterfall.png
Orbcomm Orbcomm satellites are used for monitoring and sending short text messages. 137 MHz137,000,000 Hz
137,000 kHz
, 150 MHz150,000,000 Hz
150,000 kHz
NFM 15,000 Hz15 kHz
0.015 MHz
Worldwide Orbcomm Waterfall.jpg
Over the Horizon Radar (OTH) Used by militaries for very long range radar systems. 6 MHz6,000,000 Hz
6,000 kHz
None 0 Hz0 kHz
0 MHz
Worldwide OTHRadar Waterfall.png
Overlapping RTTY Multiple overlapping RTTY signals sent by hams. 5,346 MHz5,346,000,000 Hz
5,346,000 kHz
USB 8,000 Hz8 kHz
0.008 MHz
Worldwide OverlappingRTTY Waterfall.png
PAL TV Analogue TV Signal. Now phased out in most of the world. 60 MHz60,000,000 Hz
60,000 kHz
None 5,000,000 Hz5,000 kHz
5 MHz
Worldwide No Audio File PALTV Waterfall.jpg
POCSAG Pager digital signal. 151 MHz151,000,000 Hz
151,000 kHz
, 960 MHz960,000,000 Hz
960,000 kHz
, 138 MHz138,000,000 Hz
138,000 kHz
, 153 MHz153,000,000 Hz
153,000 kHz
, 153.5 MHz153,500,000 Hz
153,500 kHz
, 454 MHz454,000,000 Hz
454,000 kHz
, 173 MHz173,000,000 Hz
173,000 kHz
, 466.075 MHz466,075,000 Hz
466,075 kHz
, 169.625 MHz169,625,000 Hz
169,625 kHz
, 35.22 MHz35,220,000 Hz
35,220 kHz
, 35.58 MHz35,580,000 Hz
35,580 kHz
, 43.22 MHz43,220,000 Hz
43,220 kHz
, 43.58 MHz43,580,000 Hz
43,580 kHz
, 152.008 MHz152,007,500 Hz
152,007.5 kHz
, 152.48 MHz152,480,000 Hz
152,480 kHz
, 157.45 MHz157,450,000 Hz
157,450 kHz
, 158.1 MHz158,100,000 Hz
158,100 kHz
, 158.7 MHz158,700,000 Hz
158,700 kHz
, 163.25 MHz163,250,000 Hz
163,250 kHz
, 454.013 MHz454,012,500 Hz
454,012.5 kHz
, 454.5 MHz454,500,000 Hz
454,500 kHz
, 462.75 MHz462,750,000 Hz
462,750 kHz
, 465 MHz465,000,000 Hz
465,000 kHz
, 929.988 MHz929,987,500 Hz
929,987.5 kHz
, 931.988 MHz931,987,500 Hz
931,987.5 kHz
, 931.438 MHz931,437,500 Hz
931,437.5 kHz
, 931.938 MHz931,937,500 Hz
931,937.5 kHz
, 148.338 MHz148,337,500 Hz
148,337.5 kHz
, 450.375 MHz450,375,000 Hz
450,375 kHz
, 450.325 MHz450,325,000 Hz
450,325 kHz
, 465.97 MHz465,970,000 Hz
465,970 kHz
, 152.27 MHz152,270,000 Hz
152,270 kHz
, 462.925 MHz462,925,000 Hz
462,925 kHz
, 929.013 MHz929,012,500 Hz
929,012.5 kHz
, 931.013 MHz931,012,500 Hz
931,012.5 kHz
NFM 9,000 Hz9 kHz
0.009 MHz
Worldwide POCSAG Waterfall.png
Police Idling Walkie Talkie Radio Signal I found out what Unknown 453 was, the one that I posted a few weeks ago, it is a police idling signal, apparently the police signal belongs to the remote SDR I was listening to, but I got my own SDR now. So yeah, it is an idling signal for a police walkie-talkie 453.6 MHz453,600,000 Hz
453,600 kHz
 ? 0 Hz0 kHz
0 MHz
Unknown Police idling.png
Portable Traffic Lights Signals sent from portable traffic lights that are often used at roadworks. 154.463 MHz154,463,000 Hz
154,463 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide PortTrafLight Waterfall.png
Project 25 (P25) Digital voice signal. 860 MHz860,000,000 Hz
860,000 kHz
, 500 MHz500,000,000 Hz
500,000 kHz
NFM 10,000 Hz10 kHz
0.01 MHz
Worldwide P25 Waterfall.png
Project 25 Trunking (P25) Radio trunking control channel. 860 MHz860,000,000 Hz
860,000 kHz
NFM 12,500 Hz12.5 kHz
0.0125 MHz
Worldwide P25Trunk Waterfall.png
Pulse Coded Modulated (PCM) RC Toy Signal used for remote control (RC) Toys. 27.145 MHz27,145,000 Hz
27,145 kHz
, 49 MHz49,000,000 Hz
49,000 kHz
None 0 Hz0 kHz
0 MHz
Worldwide PCMRCToy Waterfall.png
Robot 72 SSTV SSTV is short for slow scan television. A method that hams and radio pirates use to transmit low resolution images. This particular image is from a fleetsatcom pirate. 252.15 MHz252,150,000 Hz
252,150 kHz
NFM 12,000 Hz12 kHz
0.012 MHz
Worldwide Robot72SSTV Waterfall.jpg
STANAG 4285 Standardization Agreement (STANAG) 4285. NATO standard for HF communication. 1.89 MHz1,890,000 Hz
1,890 kHz
, 22.7 MHz22,700,000 Hz
22,700 kHz
USB 2,500 Hz2.5 kHz
0.0025 MHz
Worldwide Stanag4285 Waterfall.png
Slow Scan Television (SSTV) Slow-scan television (SSTV) is a method for picture transmission used by amateur radio operators to transmit and receive images. 0.0142 MHz14,230 Hz
14.23 kHz
USB 0 Hz0 kHz
0 MHz
Seattle SSTV Example.png
Swedish POCSAG Minicall A short POCSAG 1200 signal used in electric plants and remote transformer and insulation stations. 161 MHz161,000,000 Hz
161,000 kHz
NFM 20,000 Hz20 kHz
0.02 MHz
Sweden SwedishMinicallPocsag Waterfall.png
Terrestrial Trunked Radio (TETRA) A professional mobile radio and two-way transceiver (walkie-talkie) specification 380 MHz380,000,000 Hz
380,000 kHz
, 430 MHz430,000,000 Hz
430,000 kHz
NFM 25,000 Hz25 kHz
0.025 MHz
Europe TETRA Waterfall.png
Toyota Car Key Wireless entry rolling code car key. 315 MHz315,000,000 Hz
315,000 kHz
, 433 MHz433,000,000 Hz
433,000 kHz
AM/FM 40,000 Hz40 kHz
0.04 MHz
Worldwide ToyotaCarFob Waterfall.png
Upper Sideband Voice Single side band, specifically upper side band. Used in the HF band by amateur radio hams and aircraft weather reports. 6 MHz6,000,000 Hz
6,000 kHz
USB 1,900 Hz1.9 kHz
0.0019 MHz
Worldwide USB Waterfall.png
VHF Data Link (VDL2) A modern version of ACARS. 136.975 MHz136,975,000 Hz
136,975 kHz
USB 25,000 Hz25 kHz
0.025 MHz
Worldwide VDL2 Waterfall.jpg
Vaisala RS92SGP Weather Balloon (Radiosonde) Weather balloon (radiosonde) telemetry data. 400 MHz400,000,000 Hz
400,000 kHz
NFM 5,500 Hz5.5 kHz
0.0055 MHz
Worldwide RS92SGP Waterfall.png
Voice Frequency Telegraph (VFT) Consists of multiple RTTY channels over one audio bandwdith. 7.454 MHz7,453,500 Hz
7,453.5 kHz
USB 8,000 Hz8 kHz
0.008 MHz
Worldwide VFT Waterfall.jpg
Weatherfax Used by mariners for receiving fax weather reports. Also Kyodo News, a Japanese newspaper transmits entire pages via Weatherfax. 3 MHz3,000,000 Hz
3,000 kHz
, 16 MHz16,000,000 Hz
16,000 kHz
NFM 5,500 Hz5.5 kHz
0.0055 MHz
Worldwide Weatherfax Waterfall.png
Wideband FM (WFM) Used for typical broadcast radio, and in some wireless headsets and speakers. 87.5 MHz87,500,000 Hz
87,500 kHz
, 108 MHz108,000,000 Hz
108,000 kHz
, 65 MHz65,000,000 Hz
65,000 kHz
, 74 MHz74,000,000 Hz
74,000 kHz
, 76 MHz76,000,000 Hz
76,000 kHz
, 90 MHz90,000,000 Hz
90,000 kHz
, 860 MHz860,000,000 Hz
860,000 kHz
WFM 54,000 Hz54 kHz
0.054 MHz
Worldwide No Audio File WFM Waterfall.jpg

Requested Signals

If you have these signals (or any other not on the list) please either add the waterfall image and sample sound as an MP3 to the wiki and edit the page, or email me at rtlsdrblog__AT__gmail__DOT__com for addition. Please consult the instructions here - Adding An Example Signal.

Automatic Link Establishment (ALE)
Continuous Wave (CW)
Emergency Managers Weather Information Network (EMWIN)
Multi Frequency Shift Keying (MFSK)
Radio Teletype (RTTY)
Tire Pressure Monitoring System (TPMS)
Voice Inversion Scrambling

Unidentified Signals

If you have an unidentified signal that you would like the wiki readers to take a look at please either email me at rtlsdrblog__at__gmail__dot__com or add it as a page yourself with the Category:UNID. Include as much information about the signal as you can including frequency, waterfall images, MP3 sound samples, location, bandwidth and anything else you can think of. Please add the signal using the correct template so that it will show up properly on the main page. Please consult the instructions here - Adding An Example Signal.

If you happen to be able to identify a signal, please either edit the wiki, make a note in the wiki discussion page (in the signal page click the discussion tab at the top), or email me at rtlsdrblog__at__gmail__dot__com.

Signal Type Description Frequency Mode Bandwidth Location Sample Audio Waterfall Image
Unknown 158 I found this signal on 158.665 MHz, which according to Industry Canada belongs to our local public works department. 158.665 MHz158,665,000 Hz
158,665 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide Unknown158 Waterfall.jpg
Unknown 167 I've recieved this signal at 167,400MHz and recorded it as NFM (Bandwidth 8000). Location: Madrid, Spain. 167.4 MHz167,400,000 Hz
167,400 kHz
NFM 8,000 Hz8 kHz
0.008 MHz
Madrid, Spain Unknown 167.png
Unknown 173 None. 173.262 MHz173,262,000 Hz
173,262 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide Unknown173 Waterfall.png
Unknown 20 IDENTIFIED - This is very likely to be Over the Horizon RADAR. 20 MHz20,000,000 Hz
20,000 kHz
 ? 0 Hz0 kHz
0 MHz
Worldwide OTH Ex2 Waterfall.jpg
Unknown 40 Hi,I found a strange signal on 40.693mhz, maybe you know what this is and/or could add this to your sample list. It has a bandwidth of about 4000-5000 hz and the low part repeats about every 2,5 seconds, the high part every 5 seconds (as shown in picture 1 rec1.png). Sometimes (2-3 times an hour) this signal has some variations - show in picture 2 rec2.png. I also provided you an audio sample of about 20 seconds, recorded in RAW. Do you know what this signal could be? Its online 24/7 since a month now. regards, Auge 409.6 MHz409,600,000 Hz
409,600 kHz
NFM 5,000 Hz5 kHz
0.005 MHz
Worldwide Unknown40 Waterfall.jpg
Unknown 40 2 Last Thursday I received some digital signals very close to each other that I have never heard before, it looked like this: and on NFM it sounded like this: appeared during sporadic E conditions and I heard a lot of people from the UK on the 50MHz band. It could very well be a signal originating from the UK, I received the signal in the south of The Netherlands. 40 MHz40,000,000 Hz
40,000 kHz
NFM 0 Hz0 kHz
0 MHz
South of The Netherlands Unknown40 2 Waterfall.jpg
Unknown 40 3 Sounds like a ringing phone. 40.672 MHz40,672,000 Hz
40,672 kHz
NFM 0 Hz0 kHz
0 MHz
Unknown40 3 Waterfall.jpg
Unknown 409 Unknown chirping like sound. 409.6 MHz409,600,000 Hz
409,600 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide Unknown409 Waterfall.jpg
Unknown 433 Hello! I was listening in the 433MHz band and saw this blip (about 1-2sec) on the waterfall on 433.873 (Millville, MA). It repeats about every 30-50 seconds, though doesn’t seem to be the same every time. Maybe a wireless instrument of some type (weather or something?). The only clear sound of it I could get was with AM, about a 4.2kHz wide filter (rtl-sdr, gqrx linux). Any ideas? Thanks!. 433 MHz433,000,000 Hz
433,000 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide [[Image:|150x250px]]
Unknown 445 Unknown. Sent from video clip.  ? 0 Hz0 kHz
0 MHz
UK Unknown445 Waterfall.png
Unknown 446 I've found a strange signal on 446 MHZ Band in Italy, it seems like a multi channel signal (maybe RTTY?). I'm attaching an image and a 2 seconds IQ sample. 446 MHz446,000,000 Hz
446,000 kHz
USB 0 Hz0 kHz
0 MHz
Worldwide Unknown446 Waterfall.jpg
Unknown 455 None. 455 MHz455,000,000 Hz
455,000 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide Unknown455 Waterfall.png
Unknown 469 Found on 469.975 FM on my ICOM HT can't get waterfall cause I don't have my RTL-SDR here. When I'll have a better recording I'll send it. It sounds like the portable traffic lights but it not the same... 469.975 MHz469,975,000 Hz
469,975 kHz
FM 0 Hz0 kHz
0 MHz
Israel [[Image:|150x250px]]
Unknown 550 Unknown FSK? 550.06 MHz550,060,000 Hz
550,060 kHz
USB 5,000 Hz5 kHz
0.005 MHz
Worldwide Unknown550 Waterfall.jpg
Unknown 72 hi I'm french I live in france. Recorded in NFM mode 72.855 MHz72,855,000 Hz
72,855 kHz
NFM 0 Hz0 kHz
0 MHz
France Unknown72 Waterfall.png
Unknown 83 Unknown 83.7 MHz83,700,000 Hz
83,700 kHz
 ? 0 Hz0 kHz
0 MHz
Unknown Unknown83 Waterfall.jpg
Unknown 856 The antenna has a Yagi pointed to West from 23.5° South latitude, 47.46° West longitude. The signal can be local or from the sky. The signal is horizontal polarized. 856 MHz856,000,000 Hz
856,000 kHz
Unknown 0 Hz0 kHz
0 MHz
Worldwide No Audio File Unknown856 Waterfall.jpg
Unknown ALE Possibly an ALE type signal?. Potentially some sort of 2G ALE signal. Similar signal shown in balints HF tour video. Also supposed as a 4xFSK from China. 6 MHz6,000,000 Hz
6,000 kHz
USB 0 Hz0 kHz
0 MHz
Worldwide UnknownALE Waterfall.png
Unknown Chirping 2 Continuous bursts. Audio sample recorded in NFM. Comment: Transmitted by a company that has water purifiers near my city. I know because i’ve done 2 stages in this company and i’ve seen the radio. It should recive the water level from the tanks and other things. 162.863 MHz162,863,000 Hz
162,863 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide UnknownChirp2 Waterfall.png
Unknown Data Chirping Continuous signal. Audio sample recorded in NFM. 152.652 MHz152,652,000 Hz
152,652 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide UnknownDataChirp Waterfall.png
Unknown Musical Signal often spotted on Sunday between morning between the 8 and 14th hour of the day. 21.07 MHz21,070,000 Hz
21,070 kHz
, 27.08 MHz27,080,000 Hz
27,080 kHz
USB 200 Hz0.2 kHz
2.0e-4 MHz
Germany Unknown Musical.jpg
Unknown Pager-Like Unknown signal that sounds similar to a POCSAG pager, but seems not to be. 26.65 MHz26,650,000 Hz
26,650 kHz
NFM 10,000 Hz10 kHz
0.01 MHz
Worldwide UnknownPagerLike Waterfall.jpg
Unknown Pulsing Periodic pulses. Sound sample recorded in USB mode. Possibly a GlobeWireless signal. 6 MHz6,000,000 Hz
6,000 kHz
USB 0 Hz0 kHz
0 MHz
Worldwide UnknownPulsing Waterfall.png
Unknown Ringing Repeats every minute. 154.646 MHz154,646,000 Hz
154,646 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide UnknownRinging Waterfall.jpg
Unknown Thin Pulsing Unknown thin pulses. 0 MHz0 Hz
0 kHz
NFM 10,000 Hz10 kHz
0.01 MHz
Unknown UnknownThinPulses Waterfall.png
Unknown Trunking Sounds like Motorola Type II smartnet, but Unitrunker does not recognize. 452.325 MHz452,325,000 Hz
452,325 kHz
NFM 0 Hz0 kHz
0 MHz
Worldwide UnknownTrunking Waterfall.png


Feel free to make comments about unidentified signals that you might know or anything else here.

Anonymous user #1

44 days ago
Score 0+-
unknown 469 is a signal from wireless alarm monitoring services. Homes and businesses with alarm systems can have a wireless transmitter for backup or for locations without a phone line.

Anonymous user #2

44 days ago
Score 0+-
unknown 550 is most likely noise from the USB interface of a PC or noise from a monitor. I have seen a very similar signal and found it to be noise from the PC.

Anonymous user #3

36 days ago
Score 0+-

I'd like to put in a request for info and signal sample on RD-LAP and also on the Motorola MDT signals that preceded the 19.2 kbps rdlap, such as MDC4800.

This is sold by Motorola as part of their DataTAC network package. It used to be active as part of the ARDIS network nationwide, but I believe that has all been retired (maybe still used somewhere? Not 100% sure)

Also, it is still used by some police departments and others with private datatac networks.


32 days ago
Score 0+-

'Unknown Lines' must be LTR Standard/LTR PassPort/LTR Net

I've submitted some samples to the admin, I think, he will put them here soon

Anonymous user #4

27 days ago
Score 0+-
Unknown chirping 2 I've been seeing something very similar on 936.924MHz USA Virginia.

Anonymous user #5

27 days ago
Score 0 You
Unknown Pager-Like is a variant of a FLEX pager.

Anonymous user #6

13 hours 40 minutes ago
Score 0+-
Unknown Musical is JT65
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