Range Measurement using Time-Difference-of-Arrival of the ATA8352

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AN4113

Range Measurement using Time-Difference-of-Arrival of the ATA8352

Introduction

The ATA8352 device is a low-power Ultra-Wideband (UWB) transceiver with an integrated security layer for secure distance bounding and point-to-point data communication. The ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver Data Sheet (DS70005450) and ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125) describe this distance bounding application using the Verifier and the Prover modes and the data communication with the RX and TX modes.

This application note describes the Time-Difference-of-Arrival (TDoA) mode of the ATA8352 device using the RX and TX modes for distance measurements and localization applications. During the TDoA mode operation, timestamps are captured when data telegrams are transmitted or received. For more details on the TDoA handling, refer to the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125). A TDoA demo application software to demonstrate the timestamp capturing is available for the UWB demo kit. Additionally, a Double-Sided Two-Way-Ranging (DS-TWR) application software is available to measure distances between the two demo kit nodes. At the Anchor node, the UWB node can act as a TDoA receiver or responder of the DS-TWR measurement. At the Tag node, the UWB node can act as a TDoA transmitter or initiator of the DS-TWR.

The distance measurement using the TDoA mode differs from the verifier and prover operation of the device, as

• The TDoA mode uses RX and TX modes, which do not use scrambled payload and, therefore, do not have the physical layer security as given by the VRs/VRso/PRs/PRso verifier and prover modes. For more details about physical layer security and payload scrambling, refer to the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125). Nevertheless, the host controller can encrypt the payload data to achieve security at the data layer.

• The application software running on the host controller controls the TDoA mode, and the UWB device controls the ranging operation in hardware while in Verifier and Prover mode.

Note: The TDoA functionality description provided in this document applies to both industrial ATA8352 and automotive ATA5352 devices.

Features

• ATA8352 Ultra-Wideband (UWB) Transceiver for Distance Bounding and Ranging Application

• Time-Difference-of-Arrival (TDoA) With ATA8352 Transceiver Device

• Angle-of-Arrival (AoA) Measurement

• Double-Sided Two-Way-Ranging (DS-TWR) With ATA8352 Transceiver Device

• Support for Wireless and Wired Synchronization

• Software Application for UWB Demo Kit

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1. Quick References

1.1 Reference Documentation

For further details, refer to the following:

• ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver Data Sheet (DS70005450)

• ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125)

• ATA8352 Demo and Evaluation Kit User's Guide (DS50003129)

• IEEE 802.15.4a-2007 Standard

• IEEE 802.15.4z-2020 Standard

1.2 Software Prerequisites

• Wireless TDoA Demo Software for ATA8352 Demo Kit

• Wired TDoA Demo Software for ATA8352 Demo Kit with Xplained Pro Extension Board and two ATA8352 Modules

• DS-TWR Demo Software for ATA8352 Demo Kit

1.3 Hardware Prerequisite

• ATA8352 UWB Demo Kit (refer to the ATA8352 Demo and Evaluation Kit User's Guide (DS50003129))

• ATA53UWB-XPRO Xplained Pro Extension Board with two UWB modules (to be attached to the SAM C21 Xplained Pro board)

1.4 Acronyms and Abbreviations

Table 1-1. Acronyms and Abbreviations

Acronym/Abbreviation Description

AoA Angle-of-Arrival

DS-TWR Double-Sided Two-Way-Ranging

FIFO First-In First-Out

IRQ Interrupt Request

IR-UWB Impulse-Radio Ultra-Wideband

MCU Microcontroller Unit

RTLS Real-Time-Location-Service

RX Receive

SNR Signal-to-Noise Ratio

TDoA Time-Difference-of-Arrival

ToA Time-of-Arrival

ToF Time-of-Flight

TWR Two-Way-Ranging

Quick References

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...continued

Acronym/Abbreviation Description

UWB Ultra-Wideband

Quick References

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2. Functional Overview

Ranging and localization applications can be summarized under the term “Multilateration”, which gives an overview about the methods and calculations. For the UWB demo kit, two demo applications are developed using the ATA8352’s TDoA capability. For more details, refer to the ATA8352 Demo and Evaluation Kit User's Guide (DS50003129).

1. TDoA application – To demonstrate the timestamp capturing with a transmitter (Tag) and receiver (Anchor) device. For more details on the TDoA application, refer to the IEEE 802.15.4a-2007 Standard.

2. DS-TWR application – To demonstrate the ranging measurement with a Tag node and an Anchor node. For more details on DS-TWR ranging, refer to the Annex D1 in the IEEE 802.15.4a-2007 Standard and section 6.9.1.2 in the IEEE 802.15.4z-2020 Standard.

2.1 TDoA

The following figure illustrates a typical TDoA application used for Real-Time-Location-Services (RTLS) in the industry that uses several Anchor nodes and Tag nodes. The Anchor nodes are fixed and the position is known, whereas the position of the mobile Tag nodes must be determined. In this application, the distances from the Tag node to the Anchor nodes must be determined, which is derived from the Time-of-Arrival (ToA) measurement and the propagation speed of light in free air.

Figure 2-1. TDoA Example Setup with Wired Clock Distribution and Synchronization

Anchor1 P1(x1,y1)

Anchor2 P2(x2,y2)

Anchor3 P3(x3,y3)

Tag PT(xt,yt) Clock,

Clock Sync, Data

TX timestamp

RX1 timestamp

RX2 timestamp

RX3 timestamp

UWB Coordinator

The ToA at the Anchor nodes with known positions is captured with timestamps to calculate the Tag position, which requires a synchronization of the clocks between the Anchor nodes to calculate the TDoA between the Anchor nodes.

The synchronization of the timestamp clock at the Anchor nodes is achieved using wired connections with synchronization pulses to synchronize the Anchor clocks (see Figure 2-1).

It is also possible to achieve synchronization with wireless communication using a reference Tag with a known position (see Figure 2-2). By measuring the ToA from the reference Tag in regular time intervals, the deviations of the timestamps at the Anchor nodes are determined. These deviations are, then, used in the TDoA calculation to correct the measured timestamps from the target Tag node.

Functional Overview

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Figure 2-2. TDoA Example Setup with Wireless Synchronization and Reference Tag

Anchor1 P1(x1,y1)

Anchor2 P2(x2,y2)

Anchor3 P3(x3,y3)

RX1 timestamp

timestampRX2

RX3 timestamp

Tag PT(xt,yt)

TX timestamp UWB

BLE, WiFi, UWB

BLE, WiFi, UWB Coordinator

Reference Tag PRT(xR,yR)

TX timestamp UWB

The following figure illustrates the timestamp capturing at the transmitter (Tag) TXT_i and the receiver (Anchor) RXA_i. The TDoA software application can display these values and the calculated differences of the timestamps in the PC terminal window. Both nodes are not synchronized and run at their own clock's frequency (f_CLKT and f_CLKA); therefore, the deviations between the subsequent ToF_i can be observed over time. This software is only for demonstration purposes, as there is only one Anchor node and no coordinator that performs the TDoA and multilateration calculations.

Figure 2-3. TDoA Demo Software Application Tag TX

(f_CLKT) t

t Anchor RX

(f_CLKA)

TXT₁ TXT₂ TXT₃

RXA₁

(TXT₁) RXA₂

(TXT₂)

RXA₃ (TXT₃)

dRXA₁ RXA₂-RXA₁ dTXT₁ TXT₂-TXT₁

dToF₁ ToF₂-ToF₁ dToF₂ ToF₃-ToF₂

dRXA₂ RXA₃-RXA₂ dTXT₂ TXT₃-TXT₂

= =

=

2.2 DS-TWR

The Double-Sided Two-Way-Ranging application exchanges a sequence of data telegrams between the nodes and captures the timestamps of these data telegrams at the transmitter and the receiver nodes to measure the distance between them. This data telegram sequence is necessary to compare the timestamps at each node and compensate for timestamp clock differences between the nodes.

As the following figure shows, one node is called Tag node, which initiates the message sequence, and the other node is called Anchor node, which responds to the message sequence. In the end, all timestamp information must be captured at least at the Anchor node to perform the distance calculation.

Functional Overview

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Figure 2-4. DS-TWR Example Setup

Anchor Tag

UWB UWB

Distance d

ToF Measurement

The following figure shows the message sequence with data telegrams and captured timestamp information.

Figure 2-5. DS-TWR Message Sequence and Timestamp Capture

Tag

(f

_CLKT

) t

Anchor t (f

_CLKA

)

TXT

₁

RXT

₂

TXT

₃

RXA

₁

(TXT

₁

) TXA

₂

RXA

₃

(TXT

₃

, RXT

₂

)

T_round1

T_round2 T_reply2

T_reply1

(TXT₁) (TXA₂) (TXT_3,RXT₂) T_round1= RXT₂– TXT₁

T_reply2= TXT₃– RXT₂ T_reply1= TXA₂– RXA₁ T_round2= RXA₃– TXA₂

Calculation at anchor:

The first data telegram is transmitted from the Tag to initiate the measurement. The timestamp TXT₁ is captured at the Tag when the first UWB pulse of the data telegram is transmitted. At the Anchor node, this data telegram is received and the timestamp RXA₁ is captured with the reception of the first pulse after the synchronization word of the data telegram (refer to the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003129) for a description of the data telegram format). With the reception of the data telegram, the Anchor node also receives the timestamp information TXT1 from the Tag in the payload of the data telegram. After a reply time (T_reply1), the Anchor node responds with a data telegram and captures the timestamps TXA₂ at the Anchor node and RXT2 at the Tag node. This is followed by a third telegram from the Tag node to the Anchor node and timestamp information TXT₃, RXT₂ and RXA₃. With the third telegram, all timestamps were received by the Anchor node to perform the calculation of the time differences Tround1, Treply1, Tround2 and Treply2.

The timestamp differences at the Tag node and the Anchor node are, then, calculated as:

Equation 2-1. Tround1

T_round1= RXT₂− TXT₁ Equation 2-2. T_round2 T_round2= RXA₃− TXA₂

Functional Overview

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Equation 2-3. T_reply1 T_reply1= TXA₂− RXA₁ Equation 2-4. T_reply2 T_reply2= TXT₃− RXT₂

With these timestamp differences, the Time-of-Flight (ToF) and the distance between the two nodes can be calculated as described in Equation 2-6 by:

Equation 2-5. Time-of-Flight (ToF)

ToF = T_round1* T_round2 − T_reply1 * T_reply2 T_round1 + T_round2 + T_reply1 + T_reply2 Equation 2-6. Distance

Distance = ToF * c

Where, c is the propagation speed of light in free air with 299766 km/s.

This measurement is implemented in the DS-TWR demo application software for the UWB demo kit.

Functional Overview

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3. Demo Kit – Software Applications

The TDoA and DS-TWR demo applications are running on the ATA8352 demo kit. For more details, refer to the ATA8352 Demo and Evaluation Kit User's Guide (DS50003129). The following figure shows that one node is used as the Tag node and the other node is the Anchor node.

The demo applications are developed using Microchip Studio 7 for the SAM C21 MCU. Both nodes are connected to a PC with a USB cable, and the virtual COM port connection is used by a PC terminal application to log the measurement data. For the COM port connection, the setup is:

• Data rate = 115.2 kBaud

• Data = 8-bit

• Parity = No

• Stop bit = 1

Figure 3-1. ATA8352 Demo Kit for TDoA and DS–TWR Application

In the wireless TDoA demo application, the Tag node transmits data telegrams every 2 seconds and the Anchor node shows the received information in the PC terminal application (see the following figure).

This demo application uses the wireless synchronization to generate an internal synchronization pulse every 170 µs. For more details on the wireless synchronization, refer to the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125).

The information and counters refer to the description in the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125) for the TDoA counters bb_t_cnt, sync_cnt and the calculated time

differences (see Figure 2-3). The receive terminal window can also show false data telegram receptions, indicated by a ‘dot (.)’. These data telegrams are recognized as invalid because of incorrect payload information. After each data telegram reception (valid or invalid), the receiver is immediately restarted.

Demo Kit – Software Applications

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Figure 3-2. Example of Measurement Data for Wireless TDoA Demo Application

Tag TX Terminal Window

Anchor RX Terminal Window

Distance between Tag and Anchor = 43 measurement every 2s (timestamp triggered)

(timestamp offset is not compensated)

The dot indicates an invalid received telegram

cm

In the DS-TWR demo application (refer to the IEEE 802.15.4z–2020 Standard), the Tag node initiates the data telegram sequence every 2 seconds and the Anchor node responds to it and shows the received information and calculated ToF and distance in a PC terminal application (see the following figure).

Figure 3-3. Example of Measurement Data of the DS-TWR Demo Application

Tag Trigger Terminal Window

Anchor Measurement Terminal Window

Distance between Tag and Anchor = 43 cm Measurement every 2s

The DS-TWR demo software application uses the message sequence described in the Figure 2-5 but uses a fourth data telegram to transmit the timestamp RXT₂ to the Anchor node. This implementation ensures the same telegram length and link budget conditions for all data telegrams. This demo application uses wireless synchronization, as described earlier.

The Tag PC terminal window shows the data telegram number and the telegram sequence for each measurement cycle. In addition, the Anchor PC terminal window shows the calculated time differences T_round1, T_reply1, T_round2 and Treply2 with a resolution of 0.1 ns together with the calculated ToF and the distance in cm. With a time resolution of

~165 ps (refer to the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125)), a distance resolution of 4.5 cm is achievable.

Another Xplained Pro Extension board is available for the Anchor node, which includes two ATA8352 modules and the logic to create a combined 48 MHz clock/synchronization signal for the wired TDoA synchronization, as described in the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125). This allows synchronization of both modules to one clock and synchronization signal generated by the host controller

Demo Kit – Software Applications

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MCU in the software application. The following figure illustrates the Anchor node with the Xplained Pro Extension board and two attached antennas.

Figure 3-4. Anchor Node for Wired TDoA Application

UWB Anchor Node

UWB modules

UWB PCB Antennas UWB Break-out board

Xplained Pro

SAM C21 Xplained Pro

OLED1 Xplained Pro

The wired TDoA software application that has to be programmed in the Anchor node uses both modules and determines the timestamp difference between these modules. The following figure illustrates the PC terminal

application window with the recorded information from both modules and the timestamp difference and mean value of the timestamp difference. This mean value is calculated from the latest 10 measurements and shows a stable value after the first 10 values of mean_diff = -9 * 165 ps = -1.485 ns, as shown in following figure at position Tag# 18.

The timestamp difference depends on the distance between the two antennas, the cable connection to the ATA8352 antenna connectors and the Tag node's position to the antennas. In the example from the preceding figure, the two antennas had a distance of 55 cm. This timestamp difference calculates the angle between the Tag node and the baseline of the two anchor antennas. The application behind is also known as the Angle-of-Arrival (AoA) measurement.

Demo Kit – Software Applications

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Figure 3-5. Example of Measurement Data for Wired TDoA Demo Application

The following figure illustrates the details for the AoA measurement and how to determine the angle (α), and Table 3-1 provides the resulting angle α for measured ToF difference values.

Figure 3-6. Angle-of-Arrival Measurement Setup

α = AoA ToF difference: dToF

Tag RF Signal

UWB-Antenna 1 Antenna Distance: d UWB-Antenna 2 Angle-of-Arrival: cos α = dToF*c / d

c is speed of light.

Table 3-1. Angle Resolution for Antenna Distance = 55 cm

dToF (165 ps) dToF (cm) α (°)

1 4.5 85.3

2 9.0 80.6

3 13.5 75.8

Demo Kit – Software Applications

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...continued

dToF (165 ps) dToF (cm) α (°)

4 18.0 70.9

5 22.5 65.9

6 27.0 60.6

7 31.5 55.1

8 36.0 49.1

9 40.5 42.6

10 45.0 35.1

11 49.5 25.8

12 54.0 10.9

Due to the time resolution of 165 ps for the timestamps, a distance resolution of about 4.5 cm is achieved. Depending on the antenna distance (d), an angle can be calculated using the AoA formula shown in the preceding figure. The table shows that the angle resolution depends on the measured angle and is between 4.7° and 14.9°. The antenna distance can change this angle resolution; that is, a larger antenna distance gives a better resolution and vice versa.

Demo Kit – Software Applications

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4. ATA8352 TDoA Implementation

The following sections describe the TDoA implementation details. For more details, refer to the ATA8352

Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver Data Sheet (DS70005450) and ATA8352 Impulse-Radio Ultra- Wideband (IR-UWB) Transceiver User's Guide (DS50003125). The TDoA operation is controlled by an additional register A29 and uses the RX and TX data communication with timestamp capturing and specialized header and footer sections as well as payload format. The timestamp capturing occurs at different positions while transmitting or receiving a TDoA data telegram. The TDoA implementation also supports wired and wireless synchronization with scheduled data telegram transmission.

The Anchor nodes within a TDoA system requires a synchronized clock to determine the timestamp differences. This can be achieved with the help of wired or wireless synchronization.

In wired synchronization, a common system clock is distributed to all Anchor nodes, which includes the system clock and the synchronization signal. This is achieved by omitting one clock pulse in the distributed clock signal at regular intervals. The following figure shows such a 48 MHz clock signal with an omitted clock pulse occurring at every 10 ms.

Figure 4-1. External 48 MHz Clock Signal with Synchronization Pulse

sync pulse

t V

_{IN_XTAL}

1.25V

0V

20.8

48 MHz External Clock Signal

ns

In wireless synchronization, each Anchor node has its own 48 MHz clock source. The synchronization is performed with internally-generated sync pulses occurring every 170 µs and requires a calibration at regular intervals with a reference Tag device.

The UWB demo kit, as shown in Figure 3-1, supports only wireless synchronization. A specialized UWB TDoA demo kit with two ATA5352-EB2 modules and clock/synchronization logic supports the generation of the wired synchronization signal, as shown in the preceding figure.

The following figure shows the hardware implementation of the UWB TDoA demo kit necessary to generate the combined clock/synchronization signal for the two ATA8352 UWB transceiver modules mounted on the demo kit PCB.

ATA8352 TDoA Implementation

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Figure 4-2. UWB TDoA External Clock/Synchronization Signal

48 MHz Clock / Synchronisation Generation

Q Q

SET

CLR

D

Q Q

SET

CLR

D

48 MHz Sync_Ena

nReset

48 MHz Sync

XTALP pin (1.25V) R1

R2 OR AND

Buffer Inverter

TX3-Q25MR-48.000M (48 MHz TXCO)

D-FlipFlop

XTALN pin Clock/Sync

Sync 48MHz

Clock/Sync Sync_Ena nReset

The Sync_Ena signal is a high pulse generated within the software application of the host MCU with a typical duration of ~10 µs and it is generated in regular intervals of about 10 ms. The synchronization pulse hardware generates the combined Clock/Sync signal on the ATA53UWB-XPRO base board, which is distributed to the two UWB ATA5352-EB2 modules with the ATA8352 UWB device. A resistor divider on the module adapts the 3.3V Clock/Sync signal to the 1.25V core domain voltage.

The captured timestamp information from the payload data during TX and RX operation is built with the two counter bb_t_cnt and sync_cnt, as described in the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125) in section 5.6 and equation 5-19 with a resolution of ~165 ps. In the case of a missing synchronization pulse in the wired mode, this equation may result in the wrong timestamp information from different devices supplied with the combined clock/synchronization signal. In such a case, it might be sufficient to use only the bb_t_cnt value, but ensure that all modules have recognized the latest sync pulse. This can be checked by reading the actual sync counter value from register A20 ID = 111 before and after the sync signal.

4.1 Measurement Accuracy

The measurements of the timestamps at the transmitter and receiver is performed at a frequency of 6.048 GHz that results in a time resolution of ~165 ps, which corresponds to the distance resolution of +/-4.5 cm. Due to physical effects like jitter and channel effects for the wireless transmissions, the achievable accuracy is less, i.e., the distance measurement variations are higher. The following figure shows a measurement distribution of 1000 measurements at a distance of 100 cm. The mean value for the distance is 97.2 cm with a standard deviation of 6.2 cm.

ATA8352 TDoA Implementation

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Figure 4-3. DS-TWR Measurements at 100 cm Distance

0 20 40 60 80 100 120 140

1 21 41 61 81 101 121 141 161 181 201 221 241 261 281 301 321 341 361 381 401 421 441 461 481 501 521 541 561 581 601 621 641 661 681 701 721 741 761 781 801 821 841 861 881 901 921 941 961 981

distance in [cm], tof in [0.1 ns

samples

tof [0.1 ns] dist [cm]

DS-TWR @ 100 cm real distance Mean distance = 97.2 cm (std = 6.2 cm)

Mean tof = 2.74 ns (std = 0.21 ns)

In addition to the distance, the figure shows the measured time-of-flight in the figure with a mean value of 2.74 ns and a standard deviation of 0.21 ns.

The Time-of-Flight (ToF) in this example does not include the distance between the ATA8352 device and the antenna, which is an offset of about 2 * 6.5 cm = 13 cm, corresponding to a ToF offset of 0.43 ns. The calculated distance shown in the preceding figure includes this offset of 13 cm.

For larger distances or in situations with low Signal-to-Noise Ratio (SNR), an additional offset occurs due to the shift of the first path signal necessary to capture the timestamps (refer to the Figure 5-23 in ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide (DS50003125)). The following figure shows the histogram of the measured distances with mean value and standard deviation.

ATA8352 TDoA Implementation

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Figure 4-4. Histogram for DS-TWR Measurements at 100 cm Distance

mean dist = 97.2 cm @ std dev = 6.2 cm

Histogram of distance measurement @ 100 cm

ATA8352 TDoA Implementation

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5. Document Revision History

Revision Date Section Description

A 07/2021 Document Initial revision

Document Revision History

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Adjacent Key Suppression, AKS, Analog-for-the-Digital Age, Any Capacitor, AnyIn, AnyOut, Augmented Switching, BlueSky, BodyCom, CodeGuard, CryptoAuthentication, CryptoAutomotive, CryptoCompanion, CryptoController, dsPICDEM, dsPICDEM.net, Dynamic Average Matching, DAM, ECAN, Espresso T1S, EtherGREEN, IdealBridge, In-Circuit Serial Programming, ICSP, INICnet, Intelligent Paralleling, Inter-Chip Connectivity, JitterBlocker, maxCrypto, maxView, memBrain, Mindi, MiWi, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, PowerSmart, PureSilicon, QMatrix, REAL ICE, Ripple Blocker, RTAX, RTG4, SAM-ICE, Serial Quad I/O, simpleMAP, SimpliPHY, SmartBuffer, SMART-I.S., storClad, SQI, SuperSwitcher, SuperSwitcher II, Switchtec, SynchroPHY, Total Endurance, TSHARC, USBCheck, VariSense, VectorBlox, VeriPHY, ViewSpan, WiperLock, XpressConnect, and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.

The Adaptec logo, Frequency on Demand, Silicon Storage Technology, and Symmcom are registered trademarks of Microchip Technology Inc. in other countries.

GestIC is a registered trademark of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries.

All other trademarks mentioned herein are property of their respective companies.

ISBN: 978-1-5224-8553-7

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Quality Management System

For information regarding Microchip’s Quality Management Systems, please visit www.microchip.com/quality.

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Range Measurement using Time-Difference-of-Arrival of the ATA8352

AN4113