ICAO Selcal

From Signal Identification Wiki
Jump to: navigation, search
ICAO Selcal
ICAO Selcall sample.jpg
Frequencies 3 MHzMegaHertz (MHz) 10^6 Hz3,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
3,000 kHzKiloHertz (kHz) 10^3 Hz
,300 MHzMegaHertz (MHz) 10^6 Hz300,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
300,000 kHzKiloHertz (kHz) 10^3 Hz
3,000 kHzKiloHertz (kHz) 10^3 Hz
MHzMegaHertz (MHz) 10^6 Hz
300,000 kHzKiloHertz (kHz) 10^3 Hz
300 MHzMegaHertz (MHz) 10^6 Hz
Frequency Range MHzMegaHertz (MHz) 10^6 Hz3,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
3,000 kHzKiloHertz (kHz) 10^3 Hz
- 300 MHzMegaHertz (MHz) 10^6 Hz300,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
300,000 kHzKiloHertz (kHz) 10^3 Hz
Mode USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)
Modulation MFSKMultiple Frequency Shift-Keying
ACF
Bandwidth 1500 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).1.5 kHzKiloHertz (kHz) 10^3 Hz
0.0015 MHzMegaHertz (MHz) 10^6 Hz
1.5 kHzKiloHertz (kHz) 10^3 Hz
0.0015 MHzMegaHertz (MHz) 10^6 Hz
1.5 kHzKiloHertz (kHz) 10^3 Hz
0.0015 MHzMegaHertz (MHz) 10^6 Hz
Location Worldwide
Short Description ICAO Selcal (also known as AVCALL, ANNEX 10, or just SELCAL) is a HFHigh Frequency (3-30 MHz)/VHFVery High Frequency (30-300 MHz) aviation selective calling system used by ground stations to initiate radio communications with aircraft.
I/Q Raw Recording
Audio Sample
ICAO Selcal (also known as AVCALL, ANNEX 10, or just SELCAL) is a HFHigh Frequency (3-30 MHz)/VHFVery High Frequency (30-300 MHz) aviation selective calling system used by ground stations to initiate radio communications with aircraft. This mode is defined by the International Civil Aviation Organization (ICAO)

The first version of Selcal in 1985 used only 12 tones (A through M except I). In 1994, the standard was extended to have 16 tones, adding tones P, Q, R, and S. With the 16 tone format, the number of possible allowable codes was extended to 10,920. Selcal codes assigned to aircraft previously use a subset of only twelve letters/tones. Therefore, more than one aircraft may be designated by the same code

Aviation Spectrum Resources, Inc. (ASRI) is the worldwide International Civil Aviation Organization (ICAO) registrar for all Selective Calling (SELCAL) system codes (This was formerly done by Aeronautical Radio, Incorporated (ARINC).) To avoid confusion from two or more aircraft using the same SELCAL code, ASRI tries to assign code duplicates to aircraft that do not usually operate in the same region of the world or on the same HFHigh Frequency (3-30 MHz) radio frequencies. However, aircraft commonly move between different geographical regions and it is now routine for two aircraft with the same SELCAL code to be found flying in the same region. Therefore, air crew always verify both SELCAL and call sign (i.e., aircraft tail registration, or telephony designator and flight identification) to be sure their aircraft is the intended recipient.

Format[edit]

The ICAO Selcal signal itself is USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) modulated with a full carrier. The radio transmissions that follow a Selcal are typically USB modulated voice without a carrier.

The Selcal follows a 2 x 2 format. The first group comprises of two simultanious tones, made of 2 of the 16 availiable tones, and lasts for 1 second. Then there is a 200ms pause before the second group, which follows the same format as the first group. Essentially, every Selcal will have a XX-XX format, where the X's are the letter codes of the tones transmitted.

ICAO Table.png


The following is a sample group of 16 Selcalls, 4 Selcalls repeated 4 times each. The decoded tones for each selcall is: AB-CD, EF-GH, JK-LM, PQ-RS. This can be used to tune your decoder.

Samples[edit]

Selcal Sample
ICAO Selcall sample.jpg

Decoding Software[edit]

Hobby Level Software
  • Sorcerer in Selcall decoder Tone Selcalls, dropdown menu ICAO
  • MultiPSK Listed in Professional Modes as "SELCAL"
Professional Equipment/Software

Video Examples[edit]


Additional Links[edit]

Additional Images[edit]