ONR WORKSHOP NOTES--

Universal Gateway Platforms

Working Group on Platforms and Sensors--Dan Frye & Jason Gobat

Universal Gateway Modem Specification & Performance Summary--Lee Freitag

Wireless Panel--Bob Heinmiller

Photos taken on January 21, 2001 (Sunday after the Workshop) This is for those of you who think the Cape doesn't get snow!!

Don Davison                        ONR                            Distributed Network Surveillance concept

Don Rosencranz                   SPAWAR                    tracking, submarine launcher systems

Michael Doctor                    CSS                             hand deployed systems, target detection

Chris Fletcher                      SPAWAR                    gateways, telesonar

Jody Wood-Putnam              CSS                             non-acoustic sensing, VSW

Chris Eagan                          NUWC                        UUV - submarine interface

Greg Duncan                        USSI                            sonobuoy systems

Adrien LaBoissonniere       Boeing                          LMRS - comms to vehicle

Clayton Jones                       WRC                           autonomous drifters, gliders

Mark Foresman                    USN                            career SEAL

Michael Wood                     USN                            Navy Special Warfare needs

Bill Stark                              Sippican                      A-size vehicles

Matt Lindel                           BAE                            offboard antenna concept, air deployed ASW

Ed Mozley                            SPAWAR                    env monitoring, air launched sondes, A-size XBT

Rick Nagle                           DSI                              EOD concepts

Steve Castelin                      CSS                             unmanned systems, VSM MCM, comm/nav relay

Sam Smith                            FAU                            AUV, comm/nav/tracking

Pierre-Philippe Beaujean     FAU                            AUV, comm/nav/tracking

Andres Folleco                    FAU                            AUV, comm/nav/tracking

Ron Merritt                          USN                            fleet support, integrate ASW/MCM

Al Manni                              NUWC                        sub-launch

Nick Venier                          NUWC                        sub-launch

Tony Matthews                     CSS                             Acomms

** Day 1 - Morning - Mission Definitions

1. ISR (Intelligence, Surveillance and Reconnaissance)

        100's of hours

        AUV or buoy deployed by air or sub 

        19 kbps from moving sensor

        Acomms - 50 kbps

        Range:     2-3 miles (repeater)

                        20+ miles

2. EOD/MCM (Explosive Ordnance Disposal/Mine Countermeasures):

       10 mile x 10 mile search

        group of AUVs

        report back acomms to multiple gateways - 5 mile or 25 mile

        64 kbps RF

        Acomm as allowed, minimum few 100 bps

3. Hydrographic reconnaissance

        Env. data - clandestine

        6-8 hours

        CTD, current, obstacles on bottom

        Modest data rate

        buoy offshore to OTH

4. Monitoring, ISR

       multiple sensors to monitor

        days to months duration

        average bit rate low

        real-time

5. pure Acomms to sub

        high acomms data rate

        long range, 75 - 100 miles

        may need repeater (RF)

        can use RF to aircraft link

6. 75 mile touch to UUV

        Reconnaissance

        ISR

        mine

7. Distributed network surveillance

        100,000 square nm

        1000 hours

        4-8 km acomm range

        network, sensor to sensor relay capability

        timely

        100's of gateways, 20 sensors each

        100 b/day heartbeat, 1000 b/intercept

8. Harbor penetration

        clandestine AUV

        listen, photos

        12 hours - weeks duration

        numerous sensors

** Day 1 - Afternoon - Mission requirements

1. ISR:

        Duration:       days to months

        Data rate:      Acomm peak 100 bps, 10  kB/minute video stills

                              RF comm = Acomm x 10

        Range:          12 miles Acomm

                              LOS and OTH RF

        Clandestine:    usually, RF LPI/LPD

        Environment:    harbors, VSW, cluttered, nearshore

        Deployment:     all options

                                 usually subsurface

                                 sometimes surface, air

        Network:          yes

2. Surveys - hydro/bathy/met - tactical:

        Duration:       6 hrs - 1 day - days

        Data rate:      low to moderate Acomms (at present)

                              current, CTD, obstacles at 20 m resolution, hearbeat

                              RF higher in bursts

        Range:          12 miles acomm (multiple gateways)

                              OTH RF

        Clandestine:    preferred

                                 low vis acceptable

                                 acoustic trade-off     

        Environment:    coastal, shallow, VSW to 100 ft

        Deployment:        surface ok, but subsurface preferred

        Network:             yes

3. MCM app - VSW:

        Duration:             hours to days

        Range:                 2 - 12 miles acomm

                                    LOS and OTH RF

        Data rate:            command/control low

                                    survey/detection higher

                                    100's to 1000's bps reacquisition

                                    identify, stills infrequent

        Environment:       VSW 10' to 40', SW 40' to 300'

        Clandestine:        preferred, not required

                                    low observable

        Deployment:        RHIB ok, subsurface preferred, also air

        Network:             important

4. Distributed Large Area Network Surveillance - ASW:

        Duration:             1000 hours (40 days)

        Range:                 5 km or longer perhaps acomm

                                    LOS or aircraft LOS RF

        Rate:                    high rate burst (xmit only) acomm

                                    20000 b/day

        Environment:       50 - 500 m depth

        Clandestine:        preferred, antenna close to surface

        Network:             yes, many gateways, many sensors

        Deployment:        all means

5. Offboard antenna:

        Duration:       hours

        Rate:           2.5 - 20 kbps

        Range:          2 - 10 km

        Environment:    > 600'

        Clandestine:    yes

        Deployment:     submarine or aircraft

        Network:        RF possibly, acomm no

6. Breadcrumb relay:

        Duration:       day - few days

        Range:          Acomms limit

                        5 km minimum (total for n links)

        Rate:           low, voice desired

        Clandestine:    definitely

        Environment:    SW, VSW, harbor

        Deployment:     subsurface

** Day 2 - Morning - Mission Deployment and Platform Options

1. ISR:

        sensor AUV launched subsurface

        gateway launched subsurface

         popup preferred:        expendable capsules

                                        glider, possibly tethered

                                        winch

                                        float

        10 - 100 cycles

2. Tactical survey:

        subsurface delivery

        glider/AUV provides flexible GW placement - better comms?

        popups have fixed position - better nav?

        10 cycles

3. MCM:

        higher nav accuracy needs

        more surface time

        10 cycles

4. Distributed network surveillance:

        glider in deepwater

        moored glider - A-size for < 200 m

        surface high % of time (popdown rather than popup idea)

        10 cycles

        could be Air Glider deployed:

        250 lbs payload, 5" diameter, 50" length or larger (100”)

5. Offboard antenna:

        surface drifter

        A-size

        air deployed

        submarine deployed

** Day 2 - Afternoon - Power (not summarized), strawmen, hard parts, test plan

Hard parts:

        Glider:    environmental limits

                        potential for fouling while surfaced

                        minimum size to achieve required buoyancy

                        antenna

                        energy issues

                        packaging

        Popup mooring:  mechanical survivability/reliability

                        surface connection

                        potential for fouling/dragging

                        self deployment

                        recovery

                        energy issues

                        packaging

Test plan:

        repeated cycles (i.e., 10) in realistic environment consistent w/ mission

        realistic recovery option

        RHIB first deployment

        demonstrate compatibility with launch methods: sub, SDV, air

        mobility required to reach op area

** Day 1 - Morning - Mission Definitions

The group had a rather free form discussion of possible missions that

might fit into the gateway concept.  The list of missions that was ultimately

presented to the larger group was: ISR, tactical survey, MCM-EOD survey,

distributed network surveillance, breadcrumb relay, and offboard antenna.

** Day 1 - Afternoon - Mission Requirements

For each of the missions defined in the morning session the group tried to refine the

requirements in the areas of: duration, range (acomms and RF), data rate (acomms and RF),

need for clandestine operation, environment, deployment mechanisms, need for networkability. 

The consensus was that networkability and clandestine operation were at least desireable

in all missions; duration ranged from hours to 40 days; most missions had

a conceptual need for both LOS and OTH RF ranges; required acomms ranges

were a few km to 12 miles; data rate were the most difficult to quantify

but given limitations already reported by the RF and Acomms working groups

most or all of the missions could work within the existing limits.

** Day 2 - Afternoon - Power (not summarized), strawmen, hard parts, test plan

The session began with an attempt to state some of the power requirements

of the various missions to get an idea of required battery sizes.  Given

the broad range of duty cycles, platform energy requirements (particularly for

buoyancy driven gliders and popups), etc. the consensus became that the

resulting range of power requirements was too broad to be useful.

The group then moved on to defining strawmen cartoons for each of the two

platforms: glider/AUV and subsurface popup.  The resultant glider design looks

like current glider technology.  The popup design had a line (with acomms

array) from the bottom to an optional subsurface fixed buoyancy unit.  The

popup unit then only needed to rise to the surface from this subsurface buoyancy.

The group concluded its effort by listing some of the important test requirements for such platforms.

Universal Gateway Modem Specification & Performance Summary - Lee Freitag

Packaging and Platform Considerations

Most of the discussion in the acoustic communications working group used the assumption that the platform would be relatively small. The smallest platform sizes considered included: ·

• A-size sonobuoy package
• Submarine Trash Disposal Unit (TDU) size (similar to the A-size sonobuoy)
• Submarine three-inch launcher size

Based on these constraints and the size of typical existing electronics used for several commercial and research modems the following size specifications were suggested as reasonable:

• A-size: about 4-in max width
• 3-in launcher: about 2.5-in max width.
• Length (typical): about 5-in (1 channel).
• Length (max): about 10-in (8 channels).

Assuming the use of standard, inexpensive ceramic the following notes may be made about the projector:

• A-size: 4.5-in ceramic yields 8 kHz resonance
• 3-in launcher: 2.75-in ceramic yields 13 kHz resonance.
• Higher frequencies are easily supported, lower harder.

It should be noted that there are other options available for acoustic sources, in particular composite technologies. However, the cost of these technologies may be higher.

The receive sensor used for the gateway modem in the proposed platforms might be:

• Same ceramic as projector in minimum-sized package.
• Several omni-directional hydrophones mounted on a vehicle. ·
• Multi-element vertical array for moored buoy. (Packed size of 8-element, 8 m array is less than 12-in within A-size tube.)

Based upon discussions of existing systems and with some extrapolation to what might fit into the proposed platforms the power required by the modem falls into these ranges:

• Power (peak): 10-100 W RMS for packet length of 1-10 seconds
• Power (receiver): 0.2-5 W (electronics). Scales with capability and thus is application-dependent.
• Power (standby mode): several mW or less.

The proposed data interface is RS-232.

Performance Estimates

The performance of the acoustic link depends upon many factors, including source level, receive array aperture, propagation conditions, Doppler shift and spread, background noise, etc. However, in order to assist in developing applications the following rules of thumb were agreed upon for primarily horizontal links in the 7-20 kHz. The link metric used was 90% or higher packet success.

• VSW max range may be about 5 km.
• SW max range may be about 10 km.

However, it should be noted that maximum ranges of 1-2 km in shallow water or very shallow water have been observed under certain propagation conditions.

Increasing the range of a point to point link requires lowering the frequency. It has been shown that ranges of 15-30 km are possible under ducted conditions at 3-5 kHz. However, signals in the 3-5 kHz band are also detectable at long ranges. Links of 12 nmi (22 km) using the 7-20 kHz band require multiple-hops. If closest node is 2 km offshore, 4 hops at 5 km each are required. It should be noted that an LPI requirement drives the maximum range and rate as well.

Typical burst rates are very difficult to estimate. However, a rough guide is:

• 50-150 bps at max range noted above or difficult channel, single receiver.
• 150-1000 bps at close range or easy channel, single receiver.
• 1000-10000 bps may be possible using vertical receiver array.

The energy efficiency of the link is estimated to have the following range. The difference of two orders of magnitude matches the typical two order of magnitude variation in signal strength due to spreading and absorption losses.

• 1 bit/Joule (max range, difficult channel).
• 100 bits/Joule (close range, easy channel).

Navigation

During navigation discussions the following points were made:

• Incorporate LBL beacon capability with modem.
• The modem can also operate as USBL homing beacon.
• Synchronous acoustic navigation is option if needed, though this requires accurate clocks or a surface expression.

Networking

The physical layer must support the data layer and the network layer. In addition, the hardware (transducer and DSP) are presumed able to handle required software and protocols.

Modem Positioning

The placement of the transducers in the water column is very important in determining performance. Modems on AUVs or adjustable moorings can operate at the depth that maximizes range. Mooring modems may need to span a large section of the water column. It should also be noted that AUVs may close range to increase data rate.

Gateway Workshop - Wireless Panel --Bob Heinmiller, Facilitator

Keith von der Heydt - Recorder

Guidelines

We proceeded on the assumption that the need was for data telemetry in coastal operations (out to 200 km), not in the open ocean.

Range, power, equipment cost, operating costs, and size/weight were considered to be significant factors.

Other -- hard to quantify -- considerations were reliability, robustness, and adaptability to covert operations.

Applications

The aim is to get data from a floating gateway platform in the coastal operations area to a facility where it can be processed and analyzed.  That facility could be ashore or on a manned vehicle (aircraft, surface vessel, or submarine).  The following are generalized scenarios:

·       Gateway to surface vessel or shore installation

·       Gateway to aircraft

·       Gateway to submarine

·       Gateway to gateway

·       Submarine to gateway to surface vessel or shore installation

Potentially, we would like to imagine a wireless LAN, on TCP/IP, with every gateway platform, vehicle, and shore facility a node on the network.  In other words, a wireless internet.  However, for our present purposes, we considered single point-to-point links.

Capabilities

The Capabilities Matrix (spreadsheet) attempts to summarize the characteristics of five options for data communications within the coastal zone. 

The options considered were:

·       High Frequency Groundwave

·       Line-of-site UHF

·       Line-of-site UHF with aircraft destination/reply

·       L- and C-band satellite

·       UHF military satcom

Only one option, line-of-sight UHF, is limited to the close inshore (20 km) zone.  Line-of-sight UHF with an aircraft replay and HF ground wave will extent to the 200 km limit, and the two satellite options (L/C band and UHF satcom) are, of course, very long range.

The matrix might be polished into a useful tool for evaluating and comparing wireless communications options in the coastal zone.

(Another, longer term option that was not discussed by the panel, but was recently suggested by Keith von der Heydt, might be spread spectrum VHF.  Oddly enough, with all the emphasis on SS in ISM bands and higher data rates and/or many channels (cell phone), the VHF band is perhaps becoming underutilized.  The necessary VHF infrastructure has been put in place for ASW purposes.  Consider the possibility of having P3 antenna's adapted for bi-directional operations in the sonobuoy band.  If the data rate of VHF SS is scaled from what we know on commercial systems such as Freewave and the like -- 26 MHZ/915 MHZ  ~  4.5 MHz/160 MHz -- what falls out is that the VHF band might well  support a 4 kbit/s SS link, allowing multiple channel use as do the Freewave-like systems.   In comparison, when scaled to a standard 375 KHz BW sonobuoy channel, we would be comparing a 1200 bps link to 56 kbps.  The digital side of the house is the same, albeit reduced rate.  The antennas on the gateway are sonobuoy-like.  There is homework to be done on the rf.  The rates are significantly lower but the infrastructure is more or less in place and the battery power would be manageable.)

Given all factors, and aiming at the greatest flexibility, we suggest that, in general, the preferred options are the HF ground wave and UHF line-of-sight with the aircraft relay.  In terms of development, both represent moderate risk.

Development Issues

The main development issues for our preferred options are:

·       Collapsible HF antennas and system integration for HF groundwave

·       Line-of-site aircraft relay system integration

In both cases, if we assume deployment from a submarine, the deployment package is also an issue.  That is, packaging the system so that it can be launched through either the three-inch tube or the trash disposal unit (TDU) on a submarine.

If a decision is made that a system can be air-dropped or thrown over the side of surface craft, this would not be an issue, of course (although some air deployment scenarios have their own size limits).  However, this would reduce the flexibility in operational use of that option.  This seems unwise.  We do not believe submarine deployment requirements pose major problems.  The HF antennas are the most difficult item in this regard, and this problem seems capable of solution.

Apart from our preferred options, there are development and integration issues in both  L-Band and C-Band systems, as noted in the matrix.

There are two development items that are independent of the wireless option chosen.

·       Standards - Intra-platform communications (plug-and-play)

We assumed that a gateway platform could be looked at as being made up of a command/control module, an acoustic comms module, and a wireless comms module.  The intra-platform communications should be standardized, and the modules should be "plug-and-play" to the extent possible. 

That is, it should be possible to make a choice of a wireless mode based on the location, data rate, etc. and plug in the appropriate module, without having to go through an elaborate configuration process each time.

RS-232 was seen by many in the panel as a simple standard for inter-module communications.  However, we suggest here that an platform-local Ethernet may be a more promising approach, and work more seamlessly with the inter-platform networking discussed in the next item.

·       Multiple-node platform and vehicle networking

Although, as noted above we considered the wireless problem in simple point-to-point mode, there was agreement that it is important to develop true multi-node routed networking among gateways, surface vessels, submarines, aircraft, and shore-based installations.  This is essential in the future utilization of gateway platforms in a network-centric battlespace. 

In other words, we envision a local internet (with or without a gateway to a wider area internet) using standard or modified TCP/IP protocols. 

An important point here is that any extra-platform communications protocols should not be designed with simple point-to-point applications in mind, lest we paint ourselves into a corner and create obstacles for future multiple-node networking.

The Navy is developing policies and standards for wireless radio-LANs.  We strongly urge that people involved in that effort be contacted, so as not to re-invent the wheel and to insure interoperability.  A good point of contact is Rex Buddenberg at the Naval Postgraduate School in Monterey, California (budden@nps.navy.mil - 831-656-3576).

Development Scenarios

We looked at five development scenarios and made rough estimates on how long each would take and for how much money.

Some of these scenarios turn out to be primarily integration jobs, others need more elaborate development, at least in certain sub-systems.  One common element was the development of deployment packages.

UHF (Freewave) Line-of-Sight

·       Repackage/integrate

·       Deployment package development

·       Test

·       Pilot project

6 months

< $0.5M

UHF (Freewave) Line-of-Sight with Aircraft Relay for Over-the-Horizon

·       Repackage/integrate

·       Aircraft UHF antenna development

·       Deployment package development

·       Test

·       Pilot project

9 months

< $0.75M

L/C-Band Satellite

·       Get carrier

·       Modify COTS hardware/software

·       Integrate/test

·       Develop deployment package

·       Test

·       Pilot project

1 year

$0.5-1.0M

C-Band Antenna (Power Reduction)

·       Integrate

·       Develop deployment package

·       Test

·       Pilot project

6 months

< $0.5M

HF Ground Wave

·       Develop collapsible antenna

·       RF transmitter/receiver/control

·       Short term over-water functional test

·       Develop deployment package

·       Test deployments

·       Pilot project

1 year

$0.75M

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