LC DELTA: Low Cost Digitally Enhanced Loran for Tactical Applications

Transcription

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2 LC DELTA: Low Cost Digitally Enhanced Loran for Tactical Applications Tom Celano Dr. Ben Peterson Chuck Schue 2

3 outline introduction / soapbox what is lc delta, aka tactical loran? requirements for tactical loran historical perspective scenarios for using lc delta alternative deployment methods key components Conclusions questions possibly some answers 3

4 what is lc delta? similar to fixed loran (site), but deployable, expeditionary, mobile, portable, relocatable, transportable all point to tactical capability additionally, works on moving vessels not entirely a new idea; however uses latest eloran technology builds upon loran recap effort prefers, but doesn t require tot control has lower cost than a fixed system fixed, en route, and terminal pnt data channel capability 4

5 requirements? small size, weight, & power (swap) easily transportable configuration rapid installation & de-installation significantly lower cost easy to use technology equivalent to strategic sites Signal specification Enhanced data channel formats hardware/software equivalent reliability & robustness 5

6 previous tactical systems loran-d (sperry gyro) 1960s 1970s 15 cycle generators pps 400-foot quick erecting tower air transportable loran system 1960s 1987 an/fpn-44 tube-type transmitter 400+ kw 625-foot tlm 6

7 previous tactical systems st mary s river mini-chain (megapulse) 1970s low power solid-state transmitters low power 150-foot rohn guyed antenna pulse/8 (racal) 1970s 1980s Low power solid-state transmitter 1kw 300-foot antenna none deployed on moving vessels 7

8 scenarios for tactical loran augmentation to improve poor coverage portable locally positioned stations single station network of stations augmentation to test station relocation port clarence to nome additional stations localized stratum-1 source component solution(s) system less antenna used during station recap 8

9 why might we need lc delta? 9

10 was nature mad at the east coast? 10

11 charley the warning shot 11

12 frances jupiter & malone i 12

13 ivan this dog will hunt! 13

14 jeanne jupiter & malone ii 14

15 or were there political factors! Accessed from the WWW. 15

16 lorsta jupiter tlm damage 16

17 last week in port clarence 17

18 last week in port clarence 18

19 sample scenario off southern fl Loran-C Station Jupiter 19

20 sample scenario off southern fl high operational interest illegal immigration drug traffic large areas of shallow water at long ranges from land the lack of loran coverage could an adversary deny gps and exploit the advantage? what could we do in response? tactical loran site land based or vessel based 20

21 50 25 sample scenario off southern fl Curves of Repeatable Accuracy in meters, Noise 52dB re 1uv/m, min SNR -10dB Carolina B Curves of Repeatable Accuracy in meters, Noise 52dB re 1uv/m, min SNR -10dB Carolina B Grangevlle + Malone Grangevlle 25 + Malone Jupiter mondvll Jupiter MobileTran Existing 7980 Coverage 7980 Coverage with Tactical Loran 21

22 sample scenario off southern fl Signal strength from MobileTran in db re 1uv/m for 10kW Loran-C Station Jupiter MobileTran Tactical Loran Asset

23 alternate deployment vessels aerostats (tethered) airships (untethered) fixed-wing aircraft large navigational buoys offshore platforms 23

24 moored aerostat 24

25 aerostat aloft 25

26 sea based aerostat 26

27 Lc delta airship aloft over city LC DELTA 27

28 tacamo vlf/lf capable aircraft 28

29 large navigational buoy 12 Meter Discus Mitch? 29

30 offshore platforms 30

31 key components: antenna tlm, slt, tip (component scenario) loop not practical quick erecting feet trailing wire smaller power = shorter antenna 31

32 key components: power prime power generator set whole/partial ups 32

33 key components: receiver mods presume 9 th pulse data channel two messages currently defined utc time & station identification differential & loran corrections 3rd not defined - early skywave warning four new proposed messages Aviation mounted transmitters two new message types one message for north data one message for east data an occasional message for emission delay maximum speeds up to 256 m/s (498 knots) maximum acceleration of 3.1 m/s 33

34 key components: receiver mods fixed transmitters same two messages as aviation transmitters set north acceleration word to non-valid number most of comms bandwidth available to support differential loran 34

35 key components: receiver mods ship-borne transmitters reference message and emission delay message sent often enough to limit time to first fix otherwise, position and velocity can fit in one message Saturation of velocity word occurs at eight m/s (15.6 knots) no acceleration data (presume modest ship maneuvers!) 35

36 key components: time recovery & signal generation Timing Subsystem Source? 10 MHz 1 PPS LORAN Signal Generation Transmitter Drive Signals Transmitter To Antenna 10 MHz 1 PPS Timing Front End Meas & Control Correction Data 36

37 key components: transmitter Predicted Loran signal strength for conductivity of 3 mmhos/meter 400 kw NSSX W 10 kw 400 kw 100 db re 1uv/m /15 kw DIGITAL AM nm 1 MW DX- LW DIGITAL LONG WAVE 37

38 conclusions the technology exists today another use of loran recap technology another use for loran data channel the cost is an order of magnitude less than a full-scale fixed site alternative deployment possibilities proof-of-concept could be done physically & fiscally possible today! questions? / comments? 38

39 GOT LORAN? 39