Beyond GPS: 5 next-gen tech­nolo­gies

Penny-sized in­er­tial sen­sors, pulsed lasers and tracked light­ning strikes are among novel ap­proaches to pro­vide pre­cise lo­ca­tion-based in­sights in GPS-de­nied ar­eas


It is dif­fi­cult to imag­ine the mod­ern world with­out the Global Po­si­tion­ing Sys­tem (GPS), which pro­vides real-time po­si­tion­ing, nav­i­ga­tion and tim­ing (PNT) data for count­less mil­i­tary and civil­ian uses. Thanks in part to early in­vest­ments that DARPA made to minia­turise GPS tech­nol­ogy, GPS to­day is ubiq­ui­tous. It’s in cars, boats, planes, trains, smart­phones and wrist­watches, and has en­abled ad­vances as wide-rang­ing as driver­less cars, pre­ci­sion mu­ni­tions, and au­to­mated sup­ply chain man­age­ment.

As rev­o­lu­tion­ary as GPS has been, how­ever, it has its lim­i­ta­tions. GPS sig­nals can­not be re­ceived un­der­ground or un­der­wa­ter and can be sig­nif­i­cantly de­graded or un­avail­able dur­ing so­lar storms. More wor­ri­some is that ad­ver­saries can jam sig­nals. GPS con­tin­ues to be vi­tal, but its lim­i­ta­tions in some en­vi­ron­ments could make it an Achilles’ heel if warfight­ers rely on it as their sole source of PNT in­for­ma­tion. To ad­dress this prob­lem, sev­eral DARPA pro­grammes are ex­plor­ing in­no­va­tive tech­nolo­gies and ap­proaches that could even­tu­ally pro­vide re­li­able, highly ac­cu­rate PNT ca­pa­bil­i­ties when GPS ca­pa­bil­i­ties are de­graded or un­avail­able.

“Po­si­tion, nav­i­ga­tion, and tim­ing are as es­sen­tial as oxy­gen for our mil­i­tary op­er­a­tors,” said Darpa Di­rec­tor Arati Prabhakar. “Now we are putting new physics, new de­vices, and new al­go­rithms on the job so our peo­ple and our sys­tems can break free of their re­liance on GPS.”

Darpa’s cur­rent PNT port­fo­lio in­cludes five pro­grams, fo­cused wholly or in part on PNT-re­lated tech­nol­ogy:

Adapt­able Nav­i­ga­tion Sys­tems (ANS) is de­vel­op­ing new al­go­rithms and ar­chi­tec­tures for rapid plug-and-play in­te­gra­tion of PNT sen­sors across mul­ti­ple plat­forms, with the in­tent to re­duce de­vel­op­ment costs and shrink de­ploy­ment time from months to days. ANS aims to cre­ate bet­ter in­er­tial mea­sure­ment de­vices by us­ing cold-atom in­ter­fer­om­e­try, which mea­sures the rel­a­tive ac­cel­er­a­tion and ro­ta­tion of a cloud of atoms stored within a sen­sor. The goal is to lever­age quantum phys­i­cal prop­er­ties to cre­ate ex­tremely ac­cu­rate in­er­tial mea­sure­ment de­vices that can op­er­ate for long pe­ri­ods with­out need­ing ex­ter­nal data to de­ter­mine time and po­si­tion. Ad­di­tion­ally, ANS seeks to ex­ploit non-nav­i­ga­tional elec­tro­mag­netic sig­nals—in­clud­ing com­mer­cial satel­lite, ra­dio and tele­vi­sion sig­nals and even light­ning strikes—to pro­vide ad­di­tional points of ref­er­ence for PNT. In com­bi­na­tion, th­ese var­i­ous sources are much more abun­dant and have stronger sig­nals than GPS, and so could pro­vide po­si­tion in­for­ma­tion in both GPS-de­nied and GPS-de­graded en­vi­ron­ments.

Mi­crotech­nol­ogy for po­si­tion­ing, nav­i­ga­tion and tim­ing (Mi­croPNT) lever­ages ex­treme minia­tur­i­sa­tion made pos­si­ble by Darpade­vel­oped mi­cro-electro­mechan­i­cal sys­tems (MEMS) tech­nol­ogy. Mi­cro-PNT com­prises a port­fo­lio of di­verse ef­forts col­lec­tively de­voted to de­velop highly sta­ble and pre­cise chip-scale gy­ro­scopes, clocks and com­plete in­te­grated tim­ing and in­er­tial mea­sure­ment de­vices. Darpa re­searchers have fab­ri­cated a pro­to­type with three gy­ro­scopes, three ac­celerom­e­ters and a highly ac­cu­rate master clock on a chip that fits eas­ily on the face of a penny. The self-cal­i­brat­ing, high-per­for­mance and cost-ef­fec­tive mi­croscale sen­sors that Darpa is de­vel­op­ing could of­fer tremen­dous size, weight and power (SWAP) im­prove­ments over ex­ist­ing sen­sors.

Quantum-As­sisted Sens­ing and Read­out (QuASAR) Quantum-as­sisted sens­ing and read­out (QuASAR) in­tends to make the world’s most ac­cu­rate atomic clocks—which cur­rently re­side in lab­o­ra­to­ries—both ro­bust and por­ta­ble. QuASAR re­searchers have de­vel­oped op­ti­cal atomic clocks in lab­o­ra­to­ries with a tim­ing er­ror of less than one sec­ond in five bil­lion years. Mak­ing clocks this pre­cise por­ta­ble could im­prove upon ex­ist­ing mil­i­tary sys­tems such as GPS, and po­ten­tially en­able en­tirely new radar, LI­DAR and metrol­ogy ap­pli­ca­tions.

The pro­gramme in ul­trafest laser sci­ence and en­gi­neer­ing (PULSE) ap­plies the lat­est in pulsed laser tech­nol­ogy to sig­nif­i­cantly im­prove the pre­ci­sion and size of atomic clocks and mi­crowave sources, en­abling more ac­cu­rate time and fre­quency syn­chro­ni­sa­tion over large dis­tances. Th­ese ca­pa­bil­i­ties are es­sen­tial to fully lever­age su­per-ac­cu­rate atomic clocks, as clocks such as those that QuASAR seeks to build are more pre­cise than our cur­rent abil­ity to syn­chro­nise be­tween them. If suc­cess­ful, PULSE tech­nol­ogy could en­able global dis­tri­bu­tion of time pre­cise enough to take ad­van­tage of the world’s most ac­cu­rate op­ti­cal atomic clocks.

The Spa­tial, Tem­po­ral and Ori­en­ta­tion in­for­ma­tion in con­tested en­vi­ron­ments (STOIC) pro­grammes seeks to de­velop PNT sys­tems that pro­vide GPS-in­de­pen­dent PNT with GPS-level tim­ing in a con­tested en­vi­ron­ment. STOIC com­prises three pri­mary el­e­ments that when in­te­grated have the po­ten­tial to pro­vide global PNT in­de­pen­dent of GPS: long-range ro­bust ref­er­ence sig­nals, ul­tra-sta­ble tac­ti­cal clocks, and mul­ti­func­tional sys­tems that pro­vide PNT in­for­ma­tion be­tween mul­ti­ples users. In time, de­pen­dence on GPS may be as unimag­in­able as is the idea to­day of liv­ing with­out it.

Darpa is pi­o­neer­ing the next-gen­er­a­tion of PNT ca­pa­bil­i­ties beyond GPS, which in­cludes us­ing minia­tur­i­sa­tion, pulsed lasers, quantum physics and even light­ning strikes for ex­ter­nal nav­i­ga­tional fixes

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