Voice of America Coverage Analysis Program VOACAP

VOACAP is free professional high-frequency (3-30 MHz) propagation prediction software from NTIA/ITS, originally developed for Voice of America (VOA). This online guide should get you well started with the software.

Need a user manual?

A more comprehensive discussion about the finer details of using the software can be found in George Lane's book Signal-to-Noise Predictions Using VOACAP. A User's Guide. The book is available on CD-ROM from Rockwell-Collins.

Need standalone VOACAP? Windows (Greg Hand) or Linux (Jim Watson).

Running any scripts to access VOACAP services is strictly prohibited unless agreed upon in advance with the VOACAP site owners.

Our services

VOACAP for Ham Radio

HF propagation predictions from 3.5 to 28 MHz.

VOACAP for Marine HF

HF propagation predictions from 2 to 25 MHz.

VOACAP for 11M

HF propagation predictions from 26 to 28 MHz.


HF propagation predictions for amateur radio DXpeditions.

VOACAP Greyline

Sun-related data for any given location, e.g. times for sunrise, sunset, dawn, dusk, solar midnight.

Space weather

Real-time Kyoto DST, Tromso A Index, Ap and Kp indices, and proton flux.