Programmable Delay of Radar Pulse Technion-Israel Institute of Technology Electrical Engineering Department

Final Presentation of Part A Project number: d1022 November 2003 Students: Guy Apelbaum Yoel Taran Supervisors: Miki Izkovitz Yosi Hipsh

Project Goal Implementation of an accurate delay system(DS) System receives a pulse as input and transmits it delayed with a given value to RF switch Delay System InOut Delay Value Pulse Delayed Pulse to RF switch

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 DS implemented as layout Connected to a PC to communicate with a user The connection is available through a 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 Start Definition of Problem Solution Proposal Hardware Implementation Software Implementation Of Chosen Solution

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

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

Possible Solutions for DS Use of high-frequency clock (~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 Counter Clk(~1GHz) Pulse Generator Pulse IN Pulse OUT

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_rise Implementation of successful pulse generator is problematic and requires use of high speed digital technology Radar pulse’s shape is unknown – what shape to generate?

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 LineSecond Line X X +/- Dev Y -/+ Dev X+Y Desired Delay

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 ? 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 Delay Lines!

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 Delay System PC InOut Controller Delay Data OR gate DIP switches For test proposals – manual controller implemented by dip switches was added

Functionality’s Description Delay Lines 3D and 3D lines manufactured by Data Delay Devices Function : delaying pulse at given value 3D D bit input data is all needed for delay lines to function properly The rest of pins are under stable logic value

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 18f I/O pins 2 Mb Program Memory USART,I^2C modules

PIC as a controller of the system - Detailed View ICD 2 Plus demonstration board PIC 18f252 RS-232 Oscilator Power PC’s GUI 3D D EEPROMEEPROM USART I^2C

PC – any personal computer with RS232 serial port available Functions : read/write operations to/from controller presentation of essential information on the screen

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

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 Idle initialization 1 Storage of Delay Values 2 Delay Modes Prompts: 1-Calibration 2-Delay

Calibration Storage of Delay Values Prompts: 1-Manually 2-Automatic 1 User enters value It is stored in RAM 2 Data file sent It is stored in RAM

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 Modes Prompts: 1-Constant Delay 2-Changing Delay(Ch.D) 3-Manually Ch.D 3 Value of Delay Is Manually Entered 2 Pulse Delay Is Changed With a Given Step 1 Pulse Delayed By a Constant Value

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

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 Delay line tested by Tektronix 500 MHz Digital Scope good performance – in limitation of measuring equipment Digital Scope 3D D TP1TP3 8 DIP Switches Pulse Generator

PIC Testing performed on demo board connected to PC Value of PIC output pins matched the desired result

Scheme of complete system testing Digital Scope 3D D TP1TP3 Pulse Generator PIC 18f252 PORT BPORT C PC

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 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 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)