Editing Have Quick (section)

{{Short description|Frequency-hopping system}}
{{Use American English|date=October 2022}}
[[File:Arc-164-rt.jpg|thumb|200px|[[Aircraft station|UHF-Aircraft station]] [[AN/ARC-164]] ''HAVE&nbsp;QUICK&nbsp;II'']]

'''Have&nbsp;Quick''' (also '''HAVEQUICK''', short '''HQ''') is an [[electronic countermeasure|ECM-resistant]] [[frequency-hopping spread spectrum|frequency-hopping system]] used to protect military [[aeronautical mobile (OR) service|aeronautical mobile (OR)]] radio traffic.

Since the end of [[World War II]], U.S. and Allied military aircraft have used AM radios in the ''NATO harmonised  225&ndash;400&nbsp;MHz UHF band'' (part of ''NATO [[B band (NATO)|B band]]''<ref>{{cite web|url=http://www.akos-rs.si/files/Zakonodaja/Direktive_in_priporocila/mednarodni_sporazumi/CM-Ag.pdf|title=''NATO C3 Board, AC/322-N/0815, "The NATO Joint Civil/Military Frequency Agreement (NJFA), ANNEXD 1, page 1-7, harmonised NATO band type 1''".|publisher=|access-date=2016-11-16|archive-date=2016-03-04|archive-url=https://web.archive.org/web/20160304102758/http://www.akos-rs.si/files/Zakonodaja/Direktive_in_priporocila/mednarodni_sporazumi/CM-Ag.pdf|url-status=dead}}</ref>) for short range air-to-air and ground-to-air communications. During development and the procurement of UHF radios, military planners did not require features to secure communications for [[aircraft]] and [[helicopter]]s from jamming until the post-[[Vietnam War]] era. Progress in electronics in the 1970s reached a point where anyone with an inexpensive radio frequency scanner or receiver set could intercept military communications. Once the target frequencies were identified, radio frequency [[Radio jamming|jamming]] could easily be employed to degrade or completely disable communications.

The Have&nbsp;Quick program was a response to this problem. Engineers recognized that newer aircraft radios already included all-channel [[frequency synthesizer]]s along with keyboards and displays for data entry. The only other system requirements to achieve the desired [[electronic counter-countermeasures|anti-jam]] functionality were an accurate clock (for timed synchronization) and a [[microprocessor]] to add [[frequency-hopping spread spectrum|frequency hopping]] to existing radios.

Aircraft and ground radios that employ HAVE&nbsp;QUICK must be initialized with accurate ''time of day'' (TOD; usually from a [[GPS]] receiver), a ''word of the day'' (WOD), and a net identifier (providing mode selection and multiple networks to use the same word of the day). A word of the day is a [[transmission security key|transmission security variable]] that consists of six segments of six digits each. The word of the day is loaded into the radio or its control unit to key the HAVE QUICK system to the proper hopping pattern, rate, and dwell time.<ref>[http://www.globalsecurity.org/military/library/policy/navy/ntsp/ARC-182-A.htm Navy Training System Plan for the AN/ARC-182(V) Radio Set, N88-NTSP-A-50-8115D/A, March 2000, Section G.1.a.(3)]</ref> The word of the day, time of day and net identifier are input to a [[cryptographically secure pseudorandom number generator|cryptographic pseudorandom number generator]] that controls the frequency changes.

HAVE&nbsp;QUICK is not an [[encryption]] system, though many HAVE&nbsp;QUICK radios can be used with encryption; e.g. the KY-58 [[VINSON]] system. HAVE&nbsp;QUICK is not compatible with [[SINCGARS]], the VHF - FM radios used by ground forces, which operate in a different radio band and use a different frequency hopping method; however some newer radios support both.