january 24, 2005techno-sciences, inc and trx proprietary 1 location and communication systems for...

January 24, 2005 Techno-Sciences, Inc and TRX Proprietary

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Location and Communication Systems for Safety Workers

TechnoSciences Inc.

and

TRX Systems


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• Determines location of safety workers.

• Communicates vital signs to base

• Determines the presence of environmental factors hazardous to safety personnel

• Operates both indoors and outside

The Fire-Safe Locator System


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Hardware Components of the Fire-Safe Locator

• The Fire-Safe Locator System Components:– One central portable base station that is

carried or worn by command firefighter or placed in truck.

– Four substations placed at key locations at emergency site.

– Personal transceivers that are worn by individual safety personnel.


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System Illustration

Central Transceiver

Satellite Transceiver

Satellite Transceiver

SatelliteTransceiver

Gone Too Far!!!


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What the Fire-Safe Locator Does

Demonstrate by Example:

Fire alarm rings. Commander takes personal transceivers and the central unit to emergency site.

• Each firefighter wears a personal transceiver that transmits a unique code.

• The central unit knows which firefighter has which code.

• The central unit communicates with each firefighter sequentially.

• During the communication sequence, the location, the vital signs, and any environmental hazard are transmitted to the base station.

• An alarm sounds if a safety worker is in trouble.


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How it Works:Technical Summary

• Each transceiver and central unit are designed using state-of-the-art CMOS electronics

• Each transceiver and the central unit is preprogrammed with a unique code.

• Each transceiver in the system is numbered.• The user (fire-chief, etc.) tells the central unit the

name of the firefighter that has each transceiver. (Each firefighter is associated with a specific transceiver.)


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How it Works:Technical Summary

• Using a digital modulation scheme, the central unit and the transceiver communicate with each other at regular intervals. (Approximately once a second.)

• Using a set of state-of-the art location algorithms involving hardware and software, the central unit determines the location of the personal transceiver and hence the firefighter.

• We have designated our state-of-the-art location algorithms as ‘Integrated Positioning’


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How Integrated Positioning Works:

Integrated Positioning combines five different technologies:

1. Global Positioning System (GPS)2. Accelerometers and Numerical Integration3. Active Radar4. Received Signal Strength Indication (RSSI)5. Orthogonal Signal Phase Delay Positioning

(OSPDP)


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Technology I: GPS

• Each personal transceiver, base station and substation will be equipped with a GPS receiver.

• The GPS location of each personal transmitter will be transmitted to the base and substations.

• Upon going indoors the GPS operation will likely terminate.

• The final location and time before GPS terminates will be recorded by the network providing a coordinate origin for the particular safety worker.


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Tech 1: GPS Progress Details

GPS Receiver(Holux GM-210)

NMEA-0183

Microcontroller

(PIC16F628)

Data Packet

Transmitter

(LINX 433Mhz RM-Series)

Receiver

(LINX 433Mhz RM-Series)

Microcontroller

(PIC16F628)

Data Packet

Computer

RS-232


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Tech 1: GPS Progress Details

•The GPS receiver receives positioning data and sends it to the microcontroller using ASCII format and the NMEA-0183 protocol.

•Data Packet Structure:The data is arranged into 80 bit packets

•Bit Sync – Alternating patter of ones and zeroes to allow receiver to easily lock onto data stream.•Frame Sync – Allows the receiving microcontroller to lock on to the data stream and verify a valid packet’s arrival.•Data Bytes – Contain data bytes to be transmitted. •CRC – Cyclic Redundancy Check. An 8 bit checksum calculated by both transmitter and receiver. This allows only valid data to be displayed.•FEC bits – Forward Error Correction. Calculated for data bytes and CRC to correct single bit errors in any byte.

•RS-232 Conversion to Computer achieved with MAX232 Level converter•Microcontroller: Microchip PIC, programmed in assembly language


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Tech. I: GPS-Receiver Interface


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Tech I: GPS Transmitter Interface (1)


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Tech. I: GPS Transmitter Interface (2)


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GPS Location Portable Display


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Prototyped GPS Data Transmitter/Receiver Pair


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Prototyped GPS Data Transmitter/Receiver Pair

With Integrated GPS Receiver and Digital Data

Transmitter


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Prototype PC Board to Integrated GPS/Digital Data Receiver


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Microprocessor Computer Interface Board for Coding Digital Data for Transmission


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Prototyped GPS and Digital Data Portable Display


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Prototyped Digital Data Translator Board Interface to Digital Transmitter


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Prototyped Accelerometer Digital Data Board


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Technology II: Accelerometers and Numerical Integration

• Equip firefighter with 3 dimensional accelerometer board (size = 3cm) and microprocessor

• Accelerometer provides instantaneous acceleration (a(t))

• Use microprocessor to numerically integrate two times to obtain instantaneous position of firefighter. (x(t) = ∫∫ a(t) dt2 + xo)

• Communicate instantaneous position to base station.


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Tech 2: AccelerometerFunctions by pulse-width modulationPulses are integrated in analog hardware.Result is fed into micro-controller to quickly obtain acceleration


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Technology III: Active Radar

• Determines distance using GHz clocks, RF pulses and the speed of light.

• Substation sends RF pulse and starts GHz clock (super high speed) at same time.

• Firefighter’s transceiver receives and returns RF pulse to substation.

• Substation receives back RF pulse and stops its clock.• Distance from Firefighter to substation calculated

Distance = (speed of light) x (elapsed clock time)• Elapsed clock time is on order of nanoseconds realized by

high speed CMOS electronics• Use 3 substations to triangulate and get precise coordinates


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UWB Pulse Generator

UWB Pulse Transmitter

GHz Clock

UWB Pulse Receiver

μCPU & Distance/ Location

RF out

RF in

Active Radar Functional Diagram

Start

Stop


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GENERATION and TRANSMISSION OF

WIDE BAND PULSES


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Clockpulse

High Pass Filter

CounterANDgate

AND

gatePower

Amp

Binary÷4

÷8

VERY NARROW PULSES

BASIC BLOCK DIAGRAM


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HIGH PASS FILTER

R = 10 KC = 1 pF

• The clock is given to the buffer• Buffer is used to get the required time delay•The high pass filter is made of MOSFET, resistor and capacitor


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Time (µs)

Time (µs)

Clock Frequency = 1 MHz

Input Clock

High Pass Filter Output

V (

Vol

ts)

V (

Vol

ts)

HIGH PASS FILTER OUTPUT


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COUNTER

• The clock is given to a binary counter• Two (÷4) and (÷8) outputs from the binary counter are given to the AND gate to generate <50% Duty Cycle Output


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COUNTER OUTPUTS

÷8 Counter Output

÷4 Counter Output

(÷4) AND (÷8) Output

Input Clock

Time (µs)

V (

Vol

ts)


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COMPLETE CIRCUIT


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Input Clock

High Pass Filter Output

Counter Output

Final Strobe Output

Time (µs)

V (

Vol

ts)

CIRCUIT OUTPUTS


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volts

STROBE OUTPUT

Time (µs)

V (

Vol

ts)Time (µs)

V (

Vol

ts)

PULSE WIDTH ~ 5 ns


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Digitally-triggered source of 1-5ns wideband pulses

A prototype a device which, when digitally triggered, will produce a very short RF signal for the purpose of calculating the distance between two units in a network, and thus their relative position.


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Schematics(simplified core)


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Principle of operation(simplified core of the circuit; monostable multivibrator)

• The circuit starts in a state where Trig is low (ground), transistor Q1 is off and transistor Q3 is on. This results in capacitor C being charged with a voltage difference of approximately [Vcc-0.7V], and the collector of Q3 is pulled low, which then turns off Q2.

• As soon as Trig goes high, Q1 is turned on. This means C begins to discharge through Q1, and thus current flows through C away from the base of Q3. Q3 then is briefly turned off, which makes the voltage on its collector go high, and current begins to flow through R4, thus turning on transistor Q2. This accelerates the discharge of C.

• This state persists until C is discharged. Then Q3 is turned back on, and its collector is pulled low. It will remain low until Trig goes back low and stays so for a time interval determined largely by the time constant of R1 and C.

• The whole cycle looks like a short voltage spike on the collector of Q3 which occurs after a high transition on Trig.


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Simulated output of a general monostable multivibrator circuit


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• This circuit can be adjusted to produce faster pulses• An output stage is added to match the output to a 50

Ohm load• RF chokes (inductors) are added to filter out low

frequency components• Every transistor is biased closer to its transition

points to accelerate response• RC constants in the circuit are reduced by reducing

the resistance and capacitance values


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Schematics (improved pulse source)


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Prototyped Analog Pulse Generator Board


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Simulated input & output


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Output, direct

The low frequency triangular spike between pulses is due to the low transition of the trigger propagating through the circuit. The oscillations are because of extra parasitic inductance added by wires on the output


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Output, high-passed through 1pF

A high-pass of the signal shows only the fast pulse, which occurs on every high-transition of the input signal, in this case is a square wave from a function generator


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FAST PULSE CONCLUSIONS

•The output pulse width obtained using High Pass Filter parameters R = 10K and C = 1pF was 5 ns.

• By changing the value of R and C we can get narrower pulses


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LNA∫ dt

Threshold Detector

Local UWB Signal

RECEIVEING FAST PULSES


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Test board for commercial high frequency mixer chips


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Technology IV: Received Signal Strength Indicator (RSSI) Overview

• The base station, substations and personal transceivers will all be equipped with an RSSI circuit that indicates the power of the signal that the firefighter is transmitting to the base station, substations (and other figherfighters).

• From the signal strength we will obtain information as to how far away a specific firefighter is from a base or substation.

• To aid in this process, local RSSI’s can be placed at known locations indoors at emergency site to monitor signal strengths’ of safety workers as well.

• RSSI information will then be transmitted to base station.


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Technology IV: Received Signal Strength Indicator (RSSI): Progress Details

LINXRXM-916-ES RF

Receiver

PIC16F88 Microcontroller

Adjustable VREF –

Adjustable VREF+

Connector for RS-232 Output


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Technology IV: Received Signal Strength Indicator (RSSI): Progress Details

•Linx receiver contains RSSI indicator corresponding to output voltage of 1.1 to 2.9V.

•PIC micro-controller has 10-bit A/D converter

•RSSI output of receiver fed directly to micro-controller

•Micro-controller outputs digital words using RS232 protocol at 9600bps.


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Tech. IV: RSSI


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Max232


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Technology V: Orthogonal Signal Phase Delay Positioning (OSPDP): Overview

• OSPDP uses synchronization of continuous pseudo-random signals to determine position.

• Suppose at time T=0, two clocks are synchronized and they both start generating a the same continuous signal.

• One clock is at the substation, and another is on the personal transmitter.

• The firefighter then moves away from the substation and both continue to generate the same continuous signal.

• Now the substation will receive the firefighter’s signal, but there will be a delay because now the firefighter’s signal must travel a finite distance to reach the substation.

• By comparing the phase difference between the two signals using inner product formulation, the distance between the substation and the fireman will be determined.

• This will be achieved with three independent substations to triangulate the precise coordinates of the firefighter.


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Tech V: Progress Phase Detector


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RF Amplifier


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1.) Distance: 0.9144 m, Phase Delay: 112.0 ns


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ResultsPhase vs. Distance

-10.00

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

0 5 10 15 20

Meters

De

gre

es Observed

Theory

Linear (Observed)


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Integrated Positioning Summary

1. We are developing a system for indoor and outdoor position detection by integrating five different technologies

2. Each technology will independently provide values for the specific location of a safety worker

3. These independent values will be transmitted to the central base station.

4. Using a voting algorithm that we are developing, the central base station will use the data from the five independent technologies to decide the most likely location of the safety personnel.

5. Vital signs and environmental factors will also be transmitted to base station. An alarm will sound if the safety worker is experiencing too high a danger factor.


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Environmental Sensors

1. Temperature

2. Infrared


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Sensors: Infrared


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Sensors: Temperature


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Computer Modeling of Radio Frequency (RF) Indoor

Location Signals


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Computer Modeling of Indoor RF Signals

• Much of indoor location is based on propagation of radio frequency (RF) electromagnetic waves.

• We have developed a unique algorithm for emulating the propagation of indoor RF.

• This capability provides a unique advantage to our Integrated Positioning Technology

• The method has been published in academic journals and received enthusiastic response.

• The technique is called the Finite Difference Time Domain Alternating Direction Implicit Method for Solving Maxwell’s Equations (FDTD-ADI).

• Maxwell’s Equations are a complicated set of partial differential vector equations that describe RF waves.

• The following slides show results of these calculations indicating how RF waves propagate inside buildings.


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Source

With Metal Stud

Wood Wall

Back

Front

Rig

ht

Lef

t

room 1

room 2

Hall Way

Simulation Geometry


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Simulation Geometry• Two Rooms: 4mx4.5m each;

• Wall • conductivity: 0.0005 S/m• Permittivity: 10 o• Thickness: 12 cm for inner wall; 20 cm

for outer wall.

• Wood Door• Conductivity: 0 S/m• Permittivity: 42 o• Cross-section: 90cmx6cm.

• Metal Stud• Conductivity: 10^7 S/m• Permittivity: o• Cross-section: 5cmx8cm• Stud spacing: 30 cm

• Otherwise: Vacuum• Conductivity: 0 S/m• Permittivity: o

Simulation Configuration

Simulation Facts

• Grid resolution 1.0 cm; 1100x750 grids are used in XY plane.

• Time step 6.0e-11 sec. Radiation source is placed at the center of the right room.

• Scenario 1:

Sinusoidal current source with f= 433 MHz.

Jz Sin(2ft) for sec

Then, switch to 0 for the rest time.

Both with and without metal wall studs are simulated

• Scenario 2:

Sinusoidal current source with f= 2.4 GHz.

Jz Sin(2ft) for sec

Then, switch to 0 for the rest time.

Both with and without metal wall studs are simulated


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433MHzWood Wall

433MHzWith metal Stud

Average Power Map of RF Signal

(Sum and average)


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2.4 GHzWith metal Stud

2.4GHzWood Wall

Average Power Map

Metal Studs cause interference pattern. Leaking power is generally less for wall with metal studs.Leaking power for 2.4Ghz excitation is larger.


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Detect First Dip Delay for signal to subside

Detecting Emitted Signal and Estimating Distance


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Wood Wall f = 433 MHz Wall with Studs f = 433 MHz

Monitoring Points: We place monitoring points on 4 sides outside the wall: 0.5m to the wall, 1.0m apart. We record the arrival time of the first dip in the received signal at the monitoring point.

Plots: The delay time dt is used to estimate the distance between the transmitter and receiver by using c x dt. In the above plots: We plot estimated distance vs. actual distance with color-coded symbols. The color represents the monitoring points on different sides as indicated in the legend. The blue line show the scenario if the estimated distance equals actual distance.


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Wood Wall f = 2.4 GHz Wall with Studs f = 2.4 GHz

Estimation error is different for monitoring at different sides.Estimation Errors due to multi-path propagation delay: F= 433 MHz: Wood Wall: Maximum Error=0.4m for distance=7.6m.

Wall with metal studs: Maximum Error=0.9m for distance=8.3m.F=2.4 GHz: Wood Wall: Maximum Error=1.0m for distance=8.3m.

Wall with metal studs: Maximum Error=1.4m for distance=8.3m.Error can be minimized by monitoring from optimized location and use magnitude info. (Stronger signal means closer to the source; near side is with less error.)

january 24, 2005techno-sciences, inc and trx proprietary 1 location and communication systems for...

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