10 April 2015


HF Data Link (HFDL) protocols are defined in the ARINC (Aeronautical Radio, Inc.) Specification 635-3, published on December 29, 2000. The development of HF Data Link service builds on the experiences of ACARS (Aircraft Communications Addressing and Reporting System), therefore HFDL is also known as HF-ACARS.
HF Data Link employs M-ary Phase Shift Keying (M-PSK) to modulate a carrier centered at RF+1440 Hz, where RF is the nominal HF carrier frequency and the characteristic single tone pre-key. The carrier is modulated with 1800 symbols per second (Baud). ACF value is 25 mSec.

ACF value
HFDL frame

Although the 1800 Bd speed, the rate at which user data is transmitted can be selected to be 300, 600, 1200 or 1800 bps. 
1800 Bd - BPSK

1800 Bd - QPSK

300 bps user data rate

No comments:

Post a Comment