Programmable delay of radar pulse
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Technion-Israel Institute of Technology Electrical Engineering Department. Programmable Delay of Radar Pulse. Final Presentation of Part A Project number: d1022 November 2003. Students: Guy Apelbaum Yoel Taran Supervisors: Miki Izkovitz Yosi Hipsh. Project Goal.

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Programmable Delay of Radar Pulse

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Programmable delay of radar pulse

Technion-Israel Institute of Technology

Electrical Engineering Department

Programmable Delay of Radar Pulse


Final presentation of part a project number d1022 november 2003

Final Presentation of Part AProject number: d1022November 2003

Students: Guy Apelbaum

Yoel Taran

Supervisors: Miki Izkovitz

Yosi Hipsh


Project goal

ProjectGoal

Delayed Pulse to RF switch

Pulse

Implementation of an accurate delay system(DS)

System receives a pulse as input and transmits it delayed with a given value to RF switch

DelaySystem

In

Out

Delay Value


Specifications

Specifications

  • Pulse’s appearance frequency lower then 1.5 MHz

  • Delay value : at range of 1 to 256 nsec

  • Delay resolution : 0.5 nsec

  • Pulse width greater then 30 nsec

  • System operates with pulses at TTL level


General guidelines

General Guidelines

  • DS implemented as layout

  • Connected to a PC to communicate with a user

  • The connection is available through a control system


Control system

Control System

Main Functionality : Connection between user and DS

Features :

Transferring value of delay from PC to DS

Performing different delay modes

User’s

PC

Control

System

Delay

System


Project flow

Project Flow

Start

Definition of Problem

Solution Proposal

Implementation

Of Chosen Solution

Hardware

Implementation

Software

Implementation


Background

Background

The DS implemented here will be a part of ECM system

Radar(we trick) works as follows : Time*Velocity = Position

where

Time = (time of propagation to the target)

Velocity = speed of wave

Position = distance from radar to the target


Programmable delay of radar pulse

DS : delays the signal and shifts the Time calculated by radaradditionally, it increases the energy of the delayed pulsethus, constantly delaying pulses we make radar follow the wrong destination !


Possible solutions for ds

Possible Solutions for DS

Use of high-frequencyclock (~1 GHz)

  • The clock starts counting while receiving pulse at input

  • When reaching the desired delay value pulse is created and is sent to RF switch

Pulse IN

Pulse OUT

Clk(~1GHz)

Counter

Pulse Generator


Programmable delay of radar pulse

Advantages:No pre-calibration of the DS is required Clocks satisfying the desired resolution are available Disadvantages:The demand for 0.5 nsec resolution requires creating pulses with short t_riseImplementation of successful pulse generator is problematic and requires use of high speed digital technology Radar pulse’s shape is unknown – what shape to generate?


Programmable delay of radar pulse

Use of delay lines

Two delay lines connected in cascade

First line :delay range from 1 to 256 nsec

resolution of 1 nsec

Second line : delay range from 1 to 64 nsec

resolution of 0.25 nsec

Result :

1 to 256 nsec range is achieved

Resolution of the total delay is 0.25 nsec

First Line

X +/- Dev

Second Line

X + Y

Desired Delay

X+Y

X

Y -/+ Dev


Programmable delay of radar pulse

Advantages:

No need in creating pulse , the original one is just delayed

Original pulse’s shape is maintained

Delay lines answering given specifications are available&cheap

Disadvantages:

The DS need to be calibrated before operating

Calibration data need to be stored = additional memory


The chosen one

Delay Lines!

The chosen one ?

And that’s because of :

Simplicity of algorithm used to achieve desired resolution

Avoidance of dealing with high speed technology

Relatively cheap prices for DS future components


Programmable delay of radar pulse

Implementation of the chosen solution:

Hardware implementation

circuit connecting between PC , controller and DS

at first – implementation as wire-up circuit

then – implementation as printed layout circuit

Software implementation

programming the controller which will watch after proper functioning of the system


Schematic view of the wire up to be built

Schematic view of the wire-up to be built

For test proposals – manual controller implemented by dip switches was added

In

Delay System

Out

Delay Data

PC

Controller

OR

gate

DIP switches


Functionality s description

Functionality’s Description

Delay Lines

3D7408-1 and 3D7408-0.25 lines

manufactured by Data Delay Devices

Function :

delaying pulse at given value

3D7408-1

3D7408-0.25

8 bit input data is all needed for delay lines to function properly The rest of pins are under stable logic value


Programmable delay of radar pulse

Controller –implemented by PIC 18f252 manufactured by Microchip

Functions :

communication with user’s PC

communication with delay lines

write/read operations with external memory

storage of several delay modes applied to DS

PIC 18f252

28 I/O pins

2 Mb Program Memory

USART,I^2C modules


Pic as a controller of the system detailed view

PIC as a controller of the system - Detailed View

ICD 2 Plus demonstration board

PC’s

GUI

EEPROM

PIC 18f252

RS-232

USART

I^2C

Oscilator

Power

3D7408-1

3D7408-0.25


Programmable delay of radar pulse

PC – any personal computer with RS232 serial port availableFunctions :read/write operations to/from controllerpresentation of essential information on the screen


Programmable delay of radar pulse

Hardware Characteristics

Voltage and Power

All units operate of 5 V DC

Current driven by the circuit – 350 mA

Implementation: Power Source of 9 V AC driving 400 mA entering 5 V DC voltage regulator

Speed Rates

1.5 MHz – delay lines max speed

4 MHz – PIC clock frequency


Programmable delay of radar pulse

Memory

2 Mb program memory on PIC

256 bytes x 5 RAM on PIC

256 Kbytes x 8 EEPROM on demo board

Interfaces

GUI : PC – user interface. Implemented by Terminal v1.9b

UART : PC – PIC interface. Implemented by USART module

located on PIC . Communication via RS232 port


Program flow

Program Flow

Idle

initialization

Prompts:

1-Calibration

2-Delay

1

Storage of

Delay Values

2

Delay

Modes


Calibration

Calibration

Prompts:

1-Manually

2-Automatic

Storage of

Delay Values

1

User enters value

It is stored in RAM

2

Data file sent

It is stored in RAM


Programmable delay of radar pulse

Notes for Calibration:

The process is done offline

Precedes delay operations

The data is stored in RAM (at this point)

The data will be stored in EEPROM(soon)


Delay

Delay

Prompts:

1-Constant Delay

2-Changing Delay(Ch.D)

3-Manually Ch.D

Delay

Modes

1

Pulse Delayed

By a Constant

Value

2

Pulse Delay

Is Changed

With a Given Step

3

Value of Delay

Is Manually

Entered


Programmable delay of radar pulse

Notes for Delay operations:

After user transfers delay value it is assigned to

delay lines pins by PIC

“Enter” pushed during any mode = back to main menu


Programmable delay of radar pulse

Software Specifications

Development tool to program PIC – ICD 2 Plus demo board

compiler – MPLAB C18

emulator – MPLAB ICE 2000

debugger – MPLAB ICD 2

programmer – PICSTART +


Testing

Testing

Delay line

tested by Tektronix 500 MHz Digital Scope

good performance – in limitation of measuring equipment

Pulse

Generator

Digital Scope

3D7408-1

3D7408-0.25

TP1

TP3

8 DIP Switches

8 DIP Switches


Programmable delay of radar pulse

PIC

Testing performed on demo board connected to PC

Value of PIC output pins matched the desired result


Scheme of complete system testing

Scheme of complete system testing

Digital Scope

Pulse

Generator

3D7408-1

3D7408-0.25

TP1

TP3

PC

PIC 18f252

PORT B

PORT C


To sum up part a of project

To Sum Up Part A of Project

The prototype of the layout was build as wire-up circuit concluding delay lines

The controller was programmed to perform specific delay functions and to communicate with user

Tests showed that delay lines drove by controller do delay pulses at values closed to expected


Conclusion

Conclusion

  • As expected – delay lines were functioning well and this gives a reason to be optimistic approaching to design the layout circuit

  • To gain desired resolution one needs to consider high speed effects presented on a line connecting delay devices.To prevent these, impedances should be matched and both delay lines should be placed on a layout

  • To measure the actual delay with needed grade of precision high-frequency (greater then 1 GHz) should be used


Part b goals

Part B Goals

  • calibration becomes automatic – tables of desired delay values are filled from scope measurements without users interference

  • delay lines are placed on a layout – to prevent reflections

  • calibration data stored in EEPROM(external memory)


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