North of Germany, operational subordinated to 2nd Allied Tactical Air Force used HQ net-group 1, whereas the southern units, subordinated to 4th Allied Tactical Air Force, used HQ net-group 2. The co-ordination of HQ radio frequency channels in the NATO-harmonised UHF-band, the design of the so-called HQ hop-sets, is provided in NATO-Europe in responsibility of the NATO Allied Radio Frequency Agency (ARFA) in Brussels. For training and exercises, HQ operates in peacetime mode with limited frequency access. Four net-numbers may be used overlapping in net-group 1 and 2. However, in tactical operation mode this limitation might be lifted. Some HQ-features are compatible to encryption hardware; e.g. to the KY-58 VINSON-family. Utilization in the US and NATO HAVE QUICK was well adopted, and as of 2007 is used on nearly all U.S. military and NATO aircraft. Improvements include HAVE QUICK II Phase 2, and a "Second generation Anti-Jam Tactical UHF Radio for NATO" called SATURN''. The latter features more complex frequency hopping. See also AN/PRC-152 AN/ARC-164 AN/PRC-117F AN/ARC-182 AN/ARC-210 B band (NATO) Combat-net radio Spread spectrum References External links AN/ARC-164 HAVE QUICK II Software Enables Radio Family Ties Airscene HAVE QUICK II Military radio systems Military radio systems of the United States Military electronics of the United States