Mode VDES

VDES: ASM frames decoded, VDE-TER bursts logged and classified.

Group	Maritime
Default frequency	161.9 MHz
Default sample rate	1 Msps
In the mode list	Maritime, VHF

Step-by-step: Tutorial-VDES

What VDES is

VDES is the successor and extension of AIS, adding terrestrial and satellite data channels in the maritime VHF band.

Frequencies and settings

VHF Data Exchange System (ITU-R M.2092): ASM on 161.975 / 162.025 MHz, VDE-TER on the 100 kHz channels at 157.2 and 161.8 MHz.

Setting	Value
Start frequency	161.9 MHz
Tuning range of the mode table	150 to 165 MHz
Sample rate asked	1 Msps
Lowest working rate	400 ksps
Channel width	400 kHz

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is Maritime, VHF.

What OnAir shows

ASM frames decoded (GMSK 9.6 kbit/s, AIS framing, CRC-16 checked, payload as hex). VDE-TER bursts detected and logged with bandwidth (25 / 50 / 100 kHz), level and a modulation class (pi/4-QPSK, 8PSK, 16QAM); their content is not decoded.

The mode's own tab has these screens: ASM messages, VDE-TER bursts. The other tabs (Overview, Receiver, Scan, History) are described on the Main window page.

Tips and caveats

• Checked with generated signals and impairments; recordings of real signals welcome.
• Which radio: Usually yes for narrowband signals: an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: Receiving ship and coast-station broadcasts is legal in many countries, with limits on using or passing on private traffic. OnAir is a receiver. Check the rules where you live. See Legal.

Related pages

• All modes, Maritime
• Supported radios, Troubleshooting, FAQ
• More in Maritime: AIS, NAVTEX, DSC, Weather fax