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EISCAT Scientific Association

System and Subsystem Design Description

EISCAT3D_PfP

System and Subsystem Design Description 2016-06-30

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Table of Contents

1 SCOPE ........................................................................................................................................... 3

1.1 IDENTIFICATION .......................................................................................................................... 3 1.2 SYSTEM OVERVIEW ..................................................................................................................... 3 1.3 PURPOSE ..................................................................................................................................... 4 1.4 APPLICATION .............................................................................................................................. 4 1.5 DEFINITIONS AND ABBREVIATIONS ............................................................................................. 5

2 REFERENCES .............................................................................................................................. 6

3 SYSTEM-WIDE DESIGN DECISIONS ..................................................................................... 7

3.1 INTERACTIONS WITH SURROUNDING SYSTEMS ............................................................................ 7 3.2 PHYSICAL ENVIRONMENT ........................................................................................................... 9 3.3 BEHAVIORAL DESIGN .................................................................................................................. 9

3.3.1 Boot and re-boot ............................................................................................................. 10 3.3.2 Calibrate receive chain................................................................................................... 12 3.3.3 Transmit .......................................................................................................................... 13 3.3.4 Receive ............................................................................................................................ 14 3.3.5 Subsystem Shutdown ....................................................................................................... 15 3.3.6 Start an Experiment ........................................................................................................ 16 3.3.7 Calibrate transmit chain ................................................................................................. 17

3.4 OVERALL DESIGN DECISIONS .................................................................................................... 18

4 SYSTEM ARCHITECTURAL DESIGN ................................................................................. 19

4.1 SYSTEM COMPONENTS .............................................................................................................. 19 4.1.1 High level interfaces ....................................................................................................... 20 4.1.2 Pulse and Steering Control Unit ..................................................................................... 24 4.1.3 Network Components ...................................................................................................... 28 4.1.4 Antenna Unit ................................................................................................................... 29 4.1.5 Time and Frequency Unit ............................................................................................... 30 4.1.6 Cables and Connectors ................................................................................................... 32 4.1.7 Transmit unit container .................................................................................................. 32 4.1.8 Climate monitoring equipment ....................................................................................... 34 4.1.9 Subsystem Manager ........................................................................................................ 34 4.1.10 Transmit Unit ............................................................................................................. 35 4.1.11 Support Structure ....................................................................................................... 39 4.1.12 Instrument Container ................................................................................................. 39 4.1.13 First Stage Receiver Unit ........................................................................................... 42

4.2 CONCEPT OF EXECUTION ........................................................................................................... 46 4.3 INTERFACE DESIGN ................................................................................................................... 47

4.3.1 Data model ..................................................................................................................... 47 4.3.2 EROS/Subsystem Manager Message Protocol ............................................................... 50

5 REQUIREMENTS ALLOCATION.......................................................................................... 51

6 NOTES ......................................................................................................................................... 52

6.1 DESCRIPTION OF DIAGRAMS ..................................................................................................... 52


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1 Scope

1.1 Identification

This System and Subsystem Design Description (SSDD) applies to the EISCAT_3D

Test Sub-array, also called “Test Sub-array” throughout this document.

1.2 System overview

The Test Sub-array is a phased-array antenna radar system containing 91 crossed

dipole antenna elements, a beamformer, a receiver, a transmitter and other subsystems

for control, time-keeping et cetera. The purpose of the Test Sub-array is to serve as a

proof of concept for the planned EISCAT_3D incoherent scatter radar system.

Diagram 1: The whole system

This diagram displays the different subsystems of the Test Sub-array and also

displays, where applicable, where the subsystems are located physically.

EISCAT_3D Test Sub-array

nc: Network Components cc: Cables and Connectors

ss: Support Structure

au: Antenna Unitic: Instrument Container

fsru: First

Stage

Receiv er Unit

pscu: Pulse

and Steering

Control Unit

tfu: Time and

Frequency

Unit

ic sm: Subsystem Manager

cme: Climate

monitoring

equipment

tuc: Transmit unit container

tu: Transmit Unit


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The support structure contains the three physical main parts Instrument Container,

Transmit Unit and Antenna Unit. There are also Network Components, Cables and

Connectors to connect everything to a complete system.

The instrument container itself contains:

Time and Frequency Unit

First Stage Receiver Unit

Climate monitoring Equipment

Pulse and Steering Control Unit

Subsystem Manger (specific for the Instrument Container)

The Transmit Unit Container simply contains the Transmit Unit and The Transmit

Unit Container simply contains the Transmit Unit and the Antenna Unit contains the

antenna elements.

Note that the diagram only displays the Test Sub-array subsystems. External systems

(e.g. Computing System which is located inside of the Instrument Container) will not

be displayed.

1.3 Purpose

The purpose of this SSDD is to provide an overall description of the Test Sub-array

system, including its logical design as well as its physical architecture down to

subsystem level.

1.4 Application

This document may be used as information to the developers and suppliers during the

development, production, integration and verification processes for the Test Sub-array

subsystems and components. The SSDD may also be used for educational purposes.

To interpret the different types of diagrams displayed in this document, please see

section Description of Diagrams for further information.

Note that the SSDD is still under construction and its contents may change.


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1.5 Definitions and Abbreviations

Definition Description

AAF Anti-Aliasing Filter

ADC Analog to Digital Converter

CPU Central Processing Unit

dBm dBm (sometimes dBmW or decibel-milliwatts) is an

abbreviation for the power ratio in decibels (dB) of the

measured power referenced to one milliwatt (mW).

(wikipedia)

EROS EISCAT Realtime Operating System

LNA Low Noise Amplifier

M&C Monitoring and Control

PfP Preparation for Production

ps picoseconds

RC Radar Controller

RF Radio Frequency

SFDR Spurious Free Dynamic Range

SNR Signal to Noise Ratio

SSDD System and Subsystem Design Description

SSPA Solid State Power Amplifier

VSWR Voltage Standing Wave Ratio

WR White Rabbit


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2 References

The systems engineering work is based on the following documents:

Reference Title

[RCM] EISCAT_3D Radar Control and Monitoring

Subsystem Report

[NGTD] EISCAT_3D: The next generation

international atmosphere and geospace

research radar Technical Description

[Impl] Implementation of EISCAT_3D Test Sub-

Array Final Version June 2016

[MD] Milestone Document MC-1

Test sub-array sub-systems and interfaces.

[SysML] SysML Distilled

[WRS] White Rabbit Specification: version 2.0

[WRSw] White Rabbit Switch: User’s Manual wr-

switch-sw-v4.2


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3 System-wide design decisions

This chapter describes the requested behavior of the Test Sub-array and the context it

will operate in, including both the actual physical environment as well as the

surrounding systems that the Test Sub-array needs to interact with in order to provide

its assigned technical functions.

3.1 Interactions with surrounding systems

The Test Sub-array will interact with a number of systems external to the Test Sub-

array. These interactions are displayed on the activity diagrams presented in chapter

Behavioral design.

The following diagram displays the surrounding systems the Test Sub-array will have

interfaces to.

Diagram 2: Operational domain

The diagram above shows the operational domain, i.e. the EISCAT_3D Test Sub-

array and its surrounding systems.

ibd [block] Operational domain [Operational domain]

Tromsö sitep74

p75

p73

p82

: EISCAT_3D

Test Sub-arrayp74

p75

p73

p82

: Antenna

Calibration

Tower

cs: Computing

System

: EROS

: EROS Power

switch

: Mains Power

1

Gb/s


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Antenna Calibration Tower

The Antenna Calibration Tower will be used during end-to-end calibration runs and

will either transmit or receive the RF signals that are sent through the receive chain

and transmit chain of the Test Sub-array. Any offsets (unexpected time delays) that

are discovered through the calibration test will be used as input to the beamformer for

example. The behavioral context of the Test Sub-array’s interactions with the Antenna

Calibration Tower is displayed on the calibrate diagrams in section "Subsystem

interaction".

The output of the beamformer is 20 (2x10) simultaneous beams which corresponds to

a data rate of about 67 Gb/s. This data is sent off for storage at the EISCAT Tromsö

site. The Tromsö site will be accessed through a wide area network (100 Mb/s

communication link using fiber Ethernet) connecting the Test Sub-array site to the

Tromsö University network.

Computing System

The computing system will, during the PfP phase, consist of a computer used to store

and process the measurement data from the First Stage Beamformer.

EISCAT_3D Test Sub-array



for control, time-keeping et cetera.

EROS

EROS (EISCAT real-time operating system) is an M&C software system that also

serves as the user interface of the Test Sub-array. EROS monitors and controls the

different subsystems through its communication with the Subsystem Managers that

are included in the subsystems. The communication consists of the exchange of

simple text messages.

EROS sends status commands inquiring about the health of the subsystems and also

sends non-time-critical control commands, for example commands related to system

startup and shutdown. These commands then initiate some kind of predefined

behavior, e.g. activities being carried out and/or information being returned. EROS

can also receive unprompted notifications from the Subsystem Manager if it detects

any anomalies.

EROS will be located inside the main building at the Tromsö site and will be accessed

through a wide area network (currently 100 Mb/s communication link using fiber

Ethernet) connecting the Test Sub-array site to the Tromsö University network. The

Slow Ethernet need will use a small part of this faster network.


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EROS Power switch

Remotely controlled independent networked power switch that allows EROS to

reboot SubMan, the software running on the Subsystem Manager computer, see

section Subsystem Manager for more information.

Mains Power

The power supply to the Test Sub-array site.

3.2 Physical environment

The site for the Test Sub-array is located in Ramfjordmoen outside of Tromsö,

Norway. Its climate has to be taken into consideration (risk of snow accumulation, et

cetera) when designing the different subsystems, and the parts of the system that have

direct interfaces with the environment also needs to be resilient to the kind of wildlife

that can be expected at the site.

3.3 Behavioral design

A smooth transition into the EISCAT_3D implementation phase as well as valuable

insights regarding system design and performance are expected through the

development and implementation of the Test Sub-array. One of the objectives is to

gain knowledge regarding how the different subsystems work together as a single Test

Sub-array, i.e. in terms of compatible interfaces, electromagnetic interference and

functionality, et cetera. The main activity of the system is simply to operate the Test

Sub-array. This activity can, in turn, be said to consist of a number of high-level sub

activities that are displayed in the following diagram:

Diagram 3: Function overview

The overall behavior of these sub activities is displayed through activity diagrams in

the following section.

Operate Test Sub-array

TransmitTransmit

Calibrate receiv e chainCalibrate receiv e chain Receiv eReceiv e

Start an ExperimentStart an ExperimentCalibrate transmit chainCalibrate transmit chain

Boot and re-bootBoot and re-boot

Subsystem ShutdownSubsystem Shutdown


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3.3.1 Boot and re-boot

The activity describes what, and which subsystems, is involved in the process of

booting and re-booting the Test Sub-array. The activity consists of two different

scenarios: one for a so called "cold start" following a mains power failure and one for

a "warm start" where SubMan is still running and can respect an exit command from

EROS.

Diagram 4: Warm Start Boot and re-boot

act [Function] Boot and re-boot [Warm Start Boot and re-boot]

Computer SubMan:EROS

Send exit

command

SubMan exitsComputer

restarts SubMan

is SubMan responding to exit command?

Terminate

process through

kill command

Shut down

SubMan

SubMan

restarts

yes

no


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Diagram 5: Cold Start Boot & re-boot after power has returned

act [Function] Boot and re-boot [Cold Start Boot & re-boot after power has returned]

:EROS Power switch Subsystem:Subsystem Manager

:Close external

power switch

:Automatic

computer boot-up

:Run SubMan

:Power up

This may or may not

occur.

:Close power

switch

If the SubMan's default behavior is

not to boot the hardware after

power failure then the hardware

needs to be booted explicitly by an

EROS command


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3.3.2 Calibrate receive chain


calibrating the receive chain of the Test Sub-array.

Diagram 6: Calibrate receive chain

act [Function] Calibrate receiv e chain [Calibrate receiv e chain]

:User:Computing System:First Stage Receiv er

Unit

:Antenna Calibration Tower

:Prepare

calibration tx

:Amplify low

signal

:Perform anti-

aliasing

:Digitize RF

signals

:Calculate offsets

etc

:Process

calibration

signals

Note that this reflects the

simplified flow and hence some

tasks and/or flows have been

omitted from this diagram

:Insert new

settings into the

Beamformer

:Receiv e

calibration

signals

:Implement new

settings

ActivityInitial

ActivityFinal


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3.3.3 Transmit

The activity describes what, and which subsystems, is involved in the Test Sub-array

transmit process: from the start signal to the radio frequency waves being emitted

from the Antenna Elements.

The “Transmit” diagram displays sequences of system tasks or activities that will be

carried out as well as the general flow between these activities over time as the Test

Sub-array is in its transmit phase. Each vertical partition represents an actor (a

subsystem, an external system or a user) that, during the transmit process, will carry

out one or several activities or tasks. The arrows on the diagram represent token flows

that simply indicate which activity is currently enabled during transmission.

Diagram 7: Transmit

act [Function] Transmit [Transmit]

:Antenna Unit:Pulse and Steering Control Unit Transmit unit

High Resolution

Trigger: Send

trigger signal

:Generate & send

RF signal

:Perform internal

system tasks

:Send Control

signals

:Switch to

transmit mode

:Receiv e

generated RF

signals

:Amplify and send

RF signals:Transmit RF

signals

Subsystems have

been primed by

EROS

Note that looping occurs until all

the scheduled transmission

waveforms have been looped

through. The behavior displayed on

this diagram is simplified and does

not explicitly describe for example

transitions to the receive state and

reception of transmission sample.


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3.3.4 Receive

The activity describes what, and which subsystems, is involved in the receive process

of the Test Sub-array: from the Antenna Elements receiving the echo signals to the

First Stage Beamformer outputting measurement data for processing and storage.

Diagram 8: Receive

act [Function] Receiv e [Receiv e]

:Pulse and Steering

Control Unit

:Computing System:First Stage Receiv er Unit:Transmit Unit:Antenna Unit

:Receiv e and

transfer RF

signals

:Receiv e

generated RF

signals

:Amplify low

signal

:Switch to receiv e

mode

:Perform anti-

aliasing

:Perform

beamforming

:Transfer beams

:Digitize RF

signals

:Send Control

signals

:Process

receiv ed beams

:Satellite echo

remov al from data

stream

ActivityInitial

ActivityFinal


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3.3.5 Subsystem Shutdown


shutting down a subsystem of the Test Sub-array.

Diagram 9: Subsystem Shutdown

act [Function] Subsystem Shutdown [Subsystem Shutdown]

:EROS Power switch Subsystem:Subsystem Manager:EROS

:Send power off

signal

:Execute

shutdown

process

:Open power

switch

:Perform

shutdown tasks

:Recycle power:Open power

switch

:Close external

power switch

ActivityFinal

ActivityInitial

SubMan responding?

YesNo


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3.3.6 Start an Experiment


starting a Test Sub-array experiment.

Diagram 10: Start an Experiment

act [Function] Start an Experiment [Start an Experiment]

:Transmit Unit:First Stage Receiv er Unit:Pulse and Steering Control Unit:Time and Frequency Unit:EROS

:Create and Send

Test Sub-array

start-up signal

:Initialize

streaming of

priming

commands

:Receiv e priming

commands

:Perform system

start-up tasks

:Receiv e priming

commands

:Perform system

start-up tasks

:Receiv e time

:Generate and

distribute time

Note that this reflects the simplified flow

and hence some tasks and/or flows have

been omitted from this diagram

:Receiv e priming

commands

:Receiv e time

:Receiv e priming

commands

Continuous flow

:Send subsystem

prepared signal

:Send subsystem

prepared signal

:Send subsystem

prepared signal

Activity final

ActivityInitial


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3.3.7 Calibrate transmit chain


calibrating the transmit chain of the Test Sub-array.

Diagram 11: Calibrate transmit chain

act [Function] Calibrate transmit chain [Calibrate transmit chain]

UserComputing system?:Antenna Calibration Tower:Pulse and Steering Control Unit :Transmit Unit:User

:Send trigger

signal

:Perform internal

system tasks

:Send Control

signals

:Generate & send

RF signal

:Receiv e

calibration signal

:Receiv e

generated RF

signals

:Insert new

settings

:Sav e and

process

calibration data

:Load calibration

pulse pattern

:Switch to

transmit mode

:Apply new

settings

The settings are applied

to the exciter, but how

this is done is TBD.


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3.4 Overall design decisions

Due to its nature, some of the subsystems of the Test Sub-array will have to be RF

shielded in order to protect them from the radiated fields in the array, as well as the

internally generated RF noise (e.g. clock signals). The following overall design

decisions have been taken to address this:

The Test Sub-array will contain two RF shielded instrument containers – one for

the Transmit System and one housing the First Stage Receiver Unit, the Pulse and

Steering Control Unit, and the Time and Frequency Unit. This solution will shield

the sensitive subsystems by preventing direct electromagnetic interference to these

from the Transmit Unit.

The design of the internal electronics will also include protection from internally

generated electromagnetic noise within the Test Sub-array


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4 System architectural design

This chapter describes the technical system that enables the behavior described in

section Behavioral design. The Test Sub-array consists of a number of subsystems

and these components are defined and described in this chapter.

This chapter displays a number of structural diagrams of the Test Sub-array and its

subsystems. See section Description of Diagrams for more information.

4.1 System components

The following diagram displays an overview of the technical subsystems of the Test

Sub-array. The arrowed lines represent the categories of interactions that have been

identified in between the subsystems. A category (e.g. status, time and RF) can

comprise a number of different signals or information flows. The external systems

that the Test Sub-array are interacting with are represented by the ports on the edge of

the diagram. For a more comprehensive view this diagram can be read together with

the "Operational Domain" diagram. Note that the diagram provides a simplified view,

thus all parts and components of the subsystems may not be visualized.


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for control, time-keeping et cetera.

Diagram 12: Test Sub-array Technical systems High level Overview

This diagram displays a high level overview of the technical subsystems of the Test

Sub-array.

4.1.1 High level interfaces

This section and following subsctions describe the highlevel interfaces of the system..

Information flows - First Stage Receiver Unit

Name Information Producer Interface

Producer

Consumer Interface

Consumer

c_73e4 EROS control

sac N/A fsr N/A

c_73e4 Status

fsr N/A sac N/A

c_73e4 Status inquiry

sac p14:Slow Ethernet fsr p04:Slow Ethernet

ibd [block] EISCAT_3D Test Sub-array [Test Sub-array Technical systems High lev el Ov erv iew]

p09: Slow Ethernet

pasc / d: Pulse and Steering Control Unit

p09: Slow Ethernet

tu / c: Transmit Unit

p79:

TBD

fsr / e: First Stage Receiv er Unit

p79:

TBD

taf / b: Time and Frequency Unitau / a: Antenna Unit

Control

Time & Sync.

Status & EROS control

Time & Sync.


Rx, Tx signals


Control, Rx


Power

Tx, Rx

External flow


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Producer

Consumer Interface

Consumer

c_75e7 Measurement data

fsr p07:Fast Ethernet EISCAT_

3D Test

Sub-array

p75:Fast Ethernet

c_89e79 TBD V

EISCAT_

3D Test

Sub-array

p89:Mechanical

and Electrical

Interface

fsr p79:TBD

c_b47e4 Time,

Synchronization

taf p47:Slow Ethernet fsr p04:Slow Ethernet

c_c31e3 Rx, Tx signals

tu N/A fsr N/A

c_d11e76 Control

pasc p11:TBD fsr p76:TBD


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Information flows - Transmit Unit


Producer

Consumer Interface

Consumer

c_73c28 EROS control

sac N/A tu N/A

c_73c28 Status

tu N/A sac N/A

c_a1c27 RF

tu N/A au N/A

c_a1c27 RF

au N/A tu N/A

c_c31e3 Rx, Tx signals

tu N/A fsr N/A

c_cd8 Control, Rx

pasc N/A tu N/A

Information flows - Time and Frequency Unit


Producer

Consumer Interface

Consumer

c_73b47 EROS control

sac N/A taf N/A

c_73b47 Status

taf N/A sac N/A

c_b47e4 Time,

Synchronization

taf p47:Slow Ethernet fsr p04:Slow Ethernet


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Information flows - Pulse and Steering Control Unit


Producer

Consumer Interface

Consumer

c_73d9 EROS control

sac N/A pasc N/A

c_73d9 Status

pasc N/A sac N/A

c_cd8 Rx, Control

pasc N/A tu N/A

c_d11e76 Control

pasc p11:TBD fsr p76:TBD


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Information flows - EROS


Producer

Consumer Interface

Consumer

c_73b47 EROS control

sac N/A taf N/A

c_73b47 Status

taf N/A sac N/A

c_73c28 EROS control

sac N/A tu N/A

c_73c28 Status

tu N/A sac N/A

c_73d9 EROS control

sac N/A pasc N/A

c_73d9 Status

pasc N/A sac N/A

c_73e4 EROS control

sac N/A fsr N/A

c_73e4 Status inquiry

sac p14:Slow Ethernet fsr p04:Slow Ethernet

c_73e4 Status

fsr N/A sac N/A

Information flows - Antenna Unit


Producer

Consumer Interface

Consumer

c_a1c27 RF

tu N/A au N/A

c_a1c27 RF

au N/A tu N/A

4.1.2 Pulse and Steering Control Unit


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The Test Sub-array subsystems are able to operate together as intended through

different control pulses or triggers that determine when the different subsystems begin

their different tasks.

The Pulse and Steering Control Unit contains the Radar Controller, the Exciter(s), a

Subsystem Manager, Power supply and an Interlock Control.

Diagram 13: Pulse and Steering Control Unit

The Subsystem Manager provides slow control input, mainly during system start-up,

and system status monitoring, see EROS in section Interactions with surrounding

systems and section Subsystem Manager for more information.

4.1.2.1 Subsystem

Exciter

The exciter generates RF signals that will be amplified and converted to analog before

distributed to the antenna elements. The signals include all information about the

frequency, phase and polarization. The exciter is also time synchronized through the

WR system.

Interlock Control

The Interlock control is an autonomous system that supervises the timing of critical

signals (e.g. the sequence in which the components are initiated and that everything is

loaded correctly) that can severely damage the hardware if not in the correct

sequence. If anything incorrect is detected the gating to the SSPA is turned off which

in turn turns off the transmit mode. Input: all signals that control the radar.

Power supply

The power supply TBD.

p11:

TBD

p08: TBD

p09:

Slow

Ethernet

p13: Slow

Ethernet

p12:

TBD

p10:

Mechanical

and

Electrical

Interface

ibd [block] Pulse and Steering Control Unit [Pulse and Steering Control Unit]

p11:

TBD

p08: TBD

p09:

Slow

Ethernet

p13: Slow

Ethernet

p12:

TBD

p10:

Mechanical

and

Electrical

Interface

e: Exciter[1..*] rc: Radar Controller[1]

sm: Subsystem Manager[1]

ic: Interlock Control[1]

: High resolution

trigger

ps: Power supply

there will be 182 (91x2)

exciter signals but the

number of physical

exciter units has not

been decided

400 V

Time,

SynchronizationTime,

Synchronization

Status

EROS

control

Interlock

control

Interlock

control Prompting

Control

RF +2

dBm Control

182182

Listens

to

{Control}


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Radar Controller

The radar controller (RC) will produce the control signals that run the radar

operations. The most important trigger is the one equal to the start of the transmitted

pulse. This trigger can be fitted with symmetric offsets – for example that the SSPA

(in the Transmit Unit) shall get its power feed before the RF begins and must hold a

bit longer than the RF signal. Also of high importance is the pulse containing the

length of the waveform. This pulse controls the Test Sub-array subsystems that are

active during the transmitting phase, whereas its offsets (so called “pre-triggers”)

control the Test Sub-array subsystems that are not active during the transmitting

phase. Radar control signals are not sent over Ethernet but via separate connectors or

industrial bus through hubs. The RC is time synchronized through the WR system.

Subsystem Manager

The Subsystem Manager consists of a network server program, “SubMan”, and a

Linux computer that SubMan runs on.

The Subsystem Manager provides a network-accessible interface between its

associated subsystem (a block of hardware with basic software and firmware that

implements a set of specific radar functionality) and EROS. The Subsystem Manager

implements SubMan that EROS communicates with in order to control and monitor

the subsystem. This is enabled by the Subsystem Manager providing a TCP socket

listener at a fixed (but configurable) network address.

SubMan receives EROS control commands that specify what the subsystem is

expected to do and SubMan also receives Status inquiry commands that specify

specific information that EROS needs SubMan to return in the form of a Status

message. SubMan also issues Notifications to EROS, without being explicitly

prompted by EROS, if it detects an anomaly of some kind, e.g. if some predefined

conditions are met (e.g. temperature exceeding a set maximum value).


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4.1.2.2 Informationflows

Name Information Producer Interface Consumer Interface

c13 RF +2 dBm

e N/A Pulse and

Steering

Control

Unit

p08:TBD

c15 Status

sm N/A Pulse and

Steering

Control

Unit

p09:Slow Ethernet

c15 EROS control

Pulse and

Steering

Control

Unit

p09:Slow Ethernet sm N/A

c16 400 V

Pulse and

Steering

Control

Unit

p10:Mechanical

and Electrical

Interface

ps N/A

c18 Control

rc N/A Pulse and

Steering

Control

Unit

p11:TBD

c22 Time,

Synchronization

Pulse and

Steering

Control

Unit

p13:Slow Ethernet e N/A

c23 Time,

Synchronization

Pulse and

Steering

Control

Unit

p13:Slow Ethernet rc N/A

c24 Interlock control

ic N/A Pulse and

Steering

Control

Unit

p12:TBD


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4.1.2.3 Interfaces

Name Type Information

p08 TBD

p09 Slow Ethernet

p10 Mechanical and

Electrical

Interface

p11 TBD to

*Transmit unit

*beamformer unit

examples:

*ack?

p12 TBD

p13 Slow Ethernet

4.1.3 Network Components

Network Components are TBD.


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4.1.4 Antenna Unit

The Antenna Unit includes the Antenna Elements, Cables and Connectors and the

Mechanical Attachment Interface to Support Structure.

The purpose of the antenna array of the Test Sub-array is to transduce the RF signals

to electromagnetic waves (or vice versa if in receive mode). The hexagonally shaped

antenna array will consist of 91 crossed-dipole Antenna Elements, hence adding up to

a total number of 182 dipoles to be sampled. The dipoles are tilted back towards the

ground plane (inverted v-shape) to enable good steering without excessive changes in

polarization ratio or antenna terminal impedance.

The Antenna Elements are mounted on a meshed metallic support structure described

in section Support Structure.

Diagram 14: Antenna unit

The diagram above simply shows the Antenna Unit containing the antenna Element.

4.1.4.1 Subsystem

Antenna Element

Dual polarized crossed inverted V-dipole. Proposed to meet IEC-norms used for

outdoor antennas with an expected lifetime of more than 15 years before service.

p02: Mechanical

Attachment Interface

p01:

TBD

ibd [block] Antenna Unit [Antenna unit]

p02: Mechanical


p01:

TBD

ae / b: Antenna Element[91]

fc:

233.3

MHz

233.3 MHz

+ 57 dBm

182182


(53)



c1 fc: 233.3 MHz

ae N/A Antenna

Unit

p01:TBD

c1 233.3 MHz + 57

dBm

Antenna

Unit

p01:TBD ae N/A

4.1.4.3 Interfaces


p01 TBD

p02 Mechanical

Attachment

Interface

4.1.5 Time and Frequency Unit

White Rabbit (WR) is a protocol developed to synchronize nodes in a packet-based

network with sub-nanosecond accuracy. The WR network consists of a set of different

so called boundary and ordinary clocks in addition to a grand master clock. WR

provides the link delay information and clock syntonization (frequency transfer) over

the physical layer with Synchronous Ethernet (SyncE). In the SyncE scheme, the WR

master (using the reference clock) encodes the outgoing data stream. The same clock

is retrieved on the other side of the physical link, and the retrieved frequency can be

further distributed. The recovered clock is also always looped back to the WR Master

(via the WR Switch) for clock phase alignment with the master.

The reference clock uses a GPS clock as the time and frequency standard (TBD). The

WR Master functions as the grand master clock and is the source of time and

frequency for the other WR clocks in the network. The WR Switch is a boundary clock

that synchronizes and syntonizes to the master clock. The reference signals retrieved

by the switch are redistributed to syntonize other slave clocks connected to its ports.

The WR Slave is an ordinary clock which retrieves the reference signals sent over a

link by the WR Master (via the WR Switch) and uses the recovered reference clock

(after a phase adjustment) for all its operations.


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Diagram 15: Time and Frequency Unit

In summary, the reference clock provides a reference phase for the transmitted and

received signals. The WR Master uses a traceable clock to encode data over SyncE.

The WR Switch then distributes the clock signal over a 1 Gbit/s Ethernet network (the

same network will also be used for inputs and outputs of EROS). The clock is then

recovered by the WR Slave which bases its timekeeping on it. The subsystems that

are time dependent can retrieve the required time and synchronization to ensure that

the system stays synchronized.

The Subsystem Manager provides slow control input, mainly during system start-up,

and system status monitoring, see section EROS for more information.

Note that this subsystem may be subject to change.


p17:

Mechanical

and

Electrical

Interface p47: Slow Ethernet

ibd [block] Time and Frequency Unit [Time and Frequency Unit]

p17:

Mechanical

and

Electrical

Interface p47: Slow Ethernet

wrm: WR Masterrc: Reference

clock

: WR Switch

Status and EROS

control sent using

SNMP protocol

230 V

230

V

EROS

control

Status

Time,

Synchronization


(53)


Status

wrm p18:Slow Ethernet Time and

Frequenc

y Unit

p47:Slow Ethernet

EROS control

Time and

Frequenc

y Unit

p47:Slow Ethernet wrm p18:Slow Ethernet

c28 230 V

Time and

Frequenc

y Unit

p17:Mechanical

and Electrical

Interface

rc p45:Mechanical

and Electrical

Interface

c32 230 V

Time and

Frequenc

y Unit

p17:Mechanical

and Electrical

Interface

wrm p26:Mechanical

and Electrical

Interface

c44 Time,

Synchronization

p21:Slow Ethernet Time and

Frequenc

y Unit

p47:Slow Ethernet

4.1.5.2 Interfaces


p17 Mechanical and

Electrical

Interface

p47 Slow Ethernet WR time

4.1.6 Cables and Connectors

The Test Sub-array also includes the Cables and Connectors necessary to connect the

different subsystems. The system component includes:

the technical solution to send the Radar control signals throughout the system

the technical solution to send the Interlock control signals throughout the

system

Note that the cables and connectors for the Antenna Elements are included in the

Antenna Unit as described in section Antenna Unit.

4.1.7 Transmit unit container

The Transmit Unit Container is container containing equipment for the transmit unit.


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Diagram 16: Transmit unit container

The diagram shows the Transmit Unit Container and its external interfaces. The

container contains the Trasmit Unit.

RF from exciter

(s): TBD

Control:

TBD

1 Gb: Slow

Ethernet

RF (Rx and

Tx signals):

TBD

3-phase:

Mechanical

and

Electrical

Interface

RF (Tx and Rx): TBD

p55: Mechanical Attachment

Interface

ibd [block] Transmit unit container [Transmit unit container]

RF from exciter

(s): TBD

Control:

TBD

1 Gb: Slow

Ethernet

RF (Rx and

Tx signals):

TBD

3-phase:

Mechanical

and

Electrical

Interface

RF (Tx and Rx): TBD

p55: Mechanical Attachment

Interface

p30

p31

p27p28p29

p32

tu: Transmit Unit

p30

p31

p27p28p29

p32


(53)

4.1.7.1 Interfaces


1 Gb Slow Ethernet

3-phase Mechanical and

Electrical

Interface

Control TBD

p55 Mechanical

Attachment

Interface

RF (Rx

and Tx

signals)

TBD

RF (Tx

and Rx)

TBD

RF from

exciter(s)

TBD

4.1.8 Climate monitoring equipment

This unit will monitor the temperature and humidity inside the Instrument Container

described in section Instrument Containers, and will send this information to the

container Subsystem Manager.

4.1.8.1 Interfaces


p49

p50 TBD

4.1.9 Subsystem Manager












(53)





4.1.9.1 Interfaces


p65 TCP socket First Stage Receiver Unit

p66 Mechanical and

Electrical

Interface

First Stage Receiver Unit. Subsystem Manager to the external

power switch.

p67 TBD First Stage Receiver Unit

p68 TBD First Stage Receiver Unit

p88 Listening TCP

socket

4.1.10 Transmit Unit

The main purpose of the Transmit Unit is to produce high-power RF pulses that are

radiated into space by the Antenna Elements. The subsystem consists of power

amplifiers, T/R switches, power supply units and a Subsystem Manager (see EROS in

section Interactions with surrounding systems and Subsystem Manager for more

information).

The power amplifiers are used to amplify the RF waveform for transmission and the

SSPA is a power amplifier that supports long pulses and high duty cycle waveforms.

The T/R Switch shifts the radar system from transmit mode (when the Transmit Unit

needs to be connected to the Antenna Unit and disconnected from the receiver) to

receive mode (when the T/R Switch will connect the incoming RF signals to the

receiver) or vice versa.

The following diagram displays the Transmit Unit, its parts, and its external

interfaces.


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Diagram 17: Transmit Unit

The diagram displays all external interfaces. When the subsystem is in transmitting

mode, the RF signal from the Pulse and Steering Control Unit is received by the

SSPA unit. After amplification the RF signal is sent to the Antenna Elements via the

T/R Switch and a, much attenuated, copy of the RF signal is also sent to the Front End

of the First Stage Receiver Unit. During receive mode the incoming RF signal is

received by the First Stage Receiver Unit via the T/R Switch.

4.1.10.1 Subsystem

Power supply


SSPA Unit

The SSPA Unit contains the T/R Switch, and is installed and operated inside the

container below the support structure for the antenna sub-array. The SSPA also

contains supervisor functions for output power, excess reflected power, excess

temperature, and other critical parameters.

Subsystem Manager









p32:

TBD

p28: Slow Ethernetp29: Mechanical and Electrical

Interface

p31:

TBD

p30:

TBD

p27:

TBD

Interlock control

interface

ibd [block] Transmit Unit [Transmit Unit]

p32:

TBD

p28: Slow Ethernetp29: Mechanical and Electrical

Interface

p31:

TBD

p30:

TBD

p27:

TBD

Interlock control

interface

sm: Subsystem Manager ps: Power supply

su: SSPA Unit

s1: SSPA[182] trs: T/R switch[182]

RF +2 dBm

Control

400 VStatus

EROS

control

fc: 233.3

MHz

233.3 MHz + 57 dBm

fc: 233.3 MHz

182 182

182 182

182

182


(53)









c37 EROS control

Transmit

Unit

p28:Slow Ethernet sm N/A

c41 Control

Transmit

Unit

p30:TBD su N/A

c42 fc: 233.3 MHz

su N/A Transmit

Unit

p31:TBD

c43 fc: 233.3 MHz

su p34:TBD Transmit

Unit

p32:TBD

c43 233.3 MHz + 57

dBm

su N/A Transmit

Unit

p32:TBD


(53)

4.1.10.3 Interfaces


Gating section 3.11.12 in the Implementation of EISCAT_3D Test

Sub-Array

Interlock

control

interface

p27 TBD

p28 Slow Ethernet Status examples:

*voltage

*temperature

p29 Mechanical and

Electrical

Interface

400 V, 3 phase

p30 TBD

p31 TBD according to section 3.11.12 in the Implementation of

EISCAT_3D Test Sub-Array Tx sample A and Tx sample B

should be -30 dB

p32 TBD

RxProtect milestone doc

T/R value


(53)

4.1.11 Support Structure

As previously described, the Antenna Elements are mounted on a meshed metallic

support structure approximately two meters above the ground, thus protecting the

elements from snow accumulation and interference caused by vegetation and wildlife.

The solution will also enable better conditions for maintenance and will provide a

support structure for the Instrument Containers described in the following section.

Diagram 18: Support Structure

The support structure diagram contains the instrument container transmit unit

container and antenna unit.

4.1.11.1 Interfaces


p46 Mechanical

Attachment

Interface

p52 Ground

Attachment

Interface

4.1.12 Instrument Container

Some of the sensitive systems and equipment are placed in an instrument container to

aid with temperature and humidity control and RF shielding (to protect the internal

electronics). Environmental and power monitoring equipment will also be placed in

the container to enable remote monitoring and control. The electrical systems located

inside the container will also include remote control capabilities to for example allow

powering down failed or interfering units. Maintenance and cost are two major factors

that will affect the design of the internal layout of the container. The Transmit Unit is

placed in its own container in order to meet the requirements described in section 3.7

Overall design decisions. To monitor the state of the Instrument Container, it will

house its own Subsystem Manager.

p46: Mechanical

Attachment Interface[91]

p52: Ground


ibd [block] Support Structure [Support Structure]

p46: Mechanical

Attachment Interface[91]

p52: Ground

Attachment Interfaceau: Antenna Unitic: Instrument Container

tuc: Transmit unit container


(53)

Diagram 19: The Instrument Container including the systems and components it is housing

The above diagram displays the instrument container and the subsystems located

inside of it. The rectangles representing the technical subsystems are dashed to reflect

that they are not parts of the instrument container.

4.1.12.1 Subsystems

Climate monitoring equipment

This unit will monitor the temperature and humidity inside the Instrument Container

described in section Instrument Containers, and will send this information to the

container Subsystem Manager.

Subsystem Manager

See section Subsystem Manager.

4.1.12.2 Interfaces


Control TBD

Measurement

data: Fast

Ethernet

RF to Transmit

unit: TBD

Time, Synch, EROS

exchange: Slow

Ethernet

RF (Rx and

Tx signals):

TBD

Control: TBD

p51: Mechanical


p53: Mechanical and

Electrical Interface

ibd [block] Instrument Container [The Instrument Container including the systems and components it is housing]

Measurement

data: Fast

Ethernet

RF to Transmit

unit: TBD

Time, Synch, EROS

exchange: Slow

Ethernet

RF (Rx and

Tx signals):

TBD

Control: TBD

p51: Mechanical


p53: Mechanical and

Electrical Interface

p07p03

p04p05

fsru: First Stage Receiv er Unit

p07p03

p04p05

p08

p11

p09p10

pscu: Pulse and Steering Control Unitp08

p11

p09p10

p47

p17

tfu: Time and Frequency Unit

p47

p17

p41

arbeta

bort

p66

ic sm: Subsystem Manager

p41

arbeta

bort

p66

cme: Climate monitoring

equipment: Computing System


(53)


Measure

ment data

Fast Ethernet

p51 Mechanical

Attachment

Interface

p53 Mechanical and

Electrical

Interface

RF (Rx

and Tx

signals)

TBD

RF to

Transmit

unit

TBD

Time,

Synch,

EROS

exchange

Slow Ethernet


(53)

4.1.13 First Stage Receiver Unit

The First Stage Receiver Unit consists of the following main subsystems: the receiver

Front End, Analogue-to-Digital converter unit, and the First Stage Beamformer. The

receiver Front End receives the wide-band, noisy signals from all the individual

antenna elements and conditions them so that they are suitable for sampling and

further digital processing. The conditioning includes frequency-band limitation by an

Anti-aliasing Filter and amplification with a Low Noise Amplifier. The conditioned

signals are then sampled with analogue-to-digital converters (ADC) and fed to the

First Stage Beamformer. The First Stage Beamformer performs the first few stages of

the digital signal processing that ultimately gives the antenna array its characteristic

directional sensitivity (“forms the antenna beams”)

Diagram 20: First Stage Receiver Unit

As shown on the diagram, the First Stage Receiver Unit consists of a Front End

(containing filters and power supply), a First Stage Beamformer, a Multichannel ADC

(and its power supply), a WR Slave, and a Subsystem Manager. The Subsystem

Manager implements SubMan that EROS communicates with in order to control and

monitor the subsystem. Note the ADC has been placed between the Front End and the

First Stage Beamformer in the diagram but it is up to the designer of the First Stage

Receiver Unit if placed inside the Front End or inside of the First Stage Beamformer.

p79: TBD

p07: Fast

Ethernet

p05:

Mechanical

and

Electrical

Interface

p04:

Slow

Ethernet

p03:

TBD

p76: TBD

ibd [block] First Stage Receiv er Unit [First Stage Receiv er Unit ]

p79: TBD

p07: Fast

Ethernet

p05:

Mechanical

and

Electrical

Interface

p04:

Slow

Ethernet

p03:

TBD

p76: TBD

p61

p63

p64 p62

p70

p77

fsb / k: First Stage Beamformer

p61

p63

p64 p62

p70

p77

p57

p59

p58

p69

fe / h: Front End

p57

p59

p58

p69

aaf: Anti-aliasing

filter

lna: LNA

ps: Power supply

LNA: Power

supply

p80

p81

adc / j : Multi channel

ADC 14 or 16 bit

p80

p81

p85

p91

ADC / n: Power supply

p85

p91

p19

WRS / m: WR Slav e

p19

p65

p68

p67

p66p88

p90

smfsr / p: Subsystem

Manager First Stage

Receiv erp65

p68

p67

p66p88

p90

TBD V

TBD

V

TBD V

TBD V

Time,

Synchronization

Status inquiry,

EROS control

Time,

Synchronization

fc: 233.3 MHz

fc: 233.3

MHzMeasurement

data

Control

14 or 16 bit data

Status

SubMan controlPower on/off

Notification, Status

Status

SubMan

control

c99


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4.1.13.1 Subsystem

First Stage Beamformer

The First Stage Beamformer is used for signal processing and provides discrete spatial

filtering across the aperture of the radar array. The system is responsible for sampling

the signals from the Antenna Elements and filtering and forming multiple receive

beams. Beamforming can, as previously mentioned, reduce the interference signals

(external electromagnetic interference) but only if the receiver chain associated with

each antenna element remains fairly linear.

The First Stage Beamformer introduces carefully calculated, antenna element specific

time delays to each of the digitized signals coming from the elements; sums the

signals coherently, that is, adds them in the voltage domain rather than in the power

domain; and performs the so called IQ-detection which converts a real-valued signal

into a complex-valued signal that represent only one side of the original two-sided

spectrum. In IQ-detection, the data flow rate, typically expressed in units of a million

samples per second (MS/s), is converted from type “NN MS/s real” to “NN/2 MS/s

complex”. Depending on the used IQ-detection method, the First Stage Beamformer

may also shift the signal to near the zero frequency. In addition, the First Stage

Beamformer may further reduce the bandwidth of the signal and the data flow rate in

a process called decimation.

The IQ-detection processing is required to produce a complex-valued sample stream

that represents information coming from a particular direction in the sky, that is, the

stream corresponds to a particular beam. It is required that up to 10 beams, in

different pointing directions, are produced simultaneously. The Beamformer

accomplishes this by using the same data samples from the Front End as above, but by

using up-to nine other sets of the element-specific time delays and repeating the

calculations. Taking into account the available two antenna polarization, a data stream

corresponding to up to 20 full bandwidth beams (in 10 directions) will be produced

out of the First Stage Beamformer.

Front End

The band-pass filtering done in the Front End has two main functions. First, it ensures

that the signal bandwidth in front of the ADC is compatible with the sampling

frequency in terms of the Nyquist criterion for bandpass sampling. The criterion states

that the periodic spectral replicas of the analog band, by the sampling frequency, must

not overlap. The other task is to prevent unwanted, often very strong, neighboring

electromagnetic signals, the out-of-band interference, of entering the digital

processing chain. This protection task of the filter can only succeed if the low noise

amplifier in front of the filter can tolerate all the extra load caused by the out-of-band

interference without losing its linearity, so that no spurious signals are generated

directly into the measurement band.

Multi channel ADC 14 or 16 bit

The ADC digitizes the signals from the Front End and outputs them to the First Stage

Beamformer.

Power supply


(53)


Subsystem Manager First Stage Receiver















WR Slave

The WR Slave extracts the time and synchronization from the 1 Gb Ethernet network

and provides it to the subsystem. The WR Slave consists of specialized WR node

cards.


(53)



c10 TBD V

First

Stage

Receiver

Unit

p05:Mechanical

and Electrical

Interface

fsb N/A

c12 Measurement data

fsb N/A First

Stage

Receiver

Unit

p07:Fast Ethernet

c2 fc: 233.3 MHz

First

Stage

Receiver

Unit

p03:TBD fe p58:TBD

c4 Time,

Synchronization

First

Stage

Receiver

Unit

p04:Slow Ethernet fe N/A

c41 Notification,

Status

smfsr p65:TCP socket First

Stage

Receiver

Unit

p04:Slow Ethernet

c42 Status inquiry,

EROS control

First

Stage

Receiver

Unit

p04:Slow Ethernet smfsr p88:Listening

TCP socket

c46 TBD V

First

Stage

Receiver

Unit

p79:TBD smfsr p66:Mechanical

and Electrical

Interface

c51 Control

First

Stage

Receiver

Unit

p76:TBD fsb p77:TBD

c7 TBD V

First

Stage

Receiver

Unit

p05:Mechanical

and Electrical

Interface

fe N/A

c8 TBD V

First

Stage

Receiver

Unit

p05:Mechanical

and Electrical

Interface

fe N/A


(53)


c99 Time,

Synchronization

First

Stage

Receiver

Unit

p04:Slow Ethernet fsb p62:TBD

4.1.13.3 Interfaces


p03 TBD Interface for receiving RF signals from the Transmit Unit.

p04 Slow Ethernet Interface for exchanging information with EROS and

receiving WR Time and Synchronization.

p05 Mechanical and

Electrical

Interface

Interface with the Mains Power.

p07 Fast Ethernet Specification TBD.

p76 TBD Interface to the Radar Controller in the Pulse and Steering

Unit.

p79 TBD External Interface to Remotely Controlled Power Switch.

Power to the Subsystem Manager.

4.2 Concept of execution

TBD. This section will display any necessary state machines and/or sequence diagram

when the information needed has been gained.


(53)

4.3 Interface design

This section will list the different information items that have been identified (see

section System components) or proposed for each Information item category.

4.3.1 Data model

The table below describes the information exchanged between the interfaces in the

system. In the table symbols △and ◆ are used to define generalisation respectively

aggregation. Generalisation can be interpreted as "a sort of" and aggregation as "part

of".

Element IK Description

Control

Time critical control signals from the Radar Controller to the

subsystems.

The Control category could be comprised of information items

such as:

* Gating from Pulse and Steering Control Unit to Transmit Unit

* T/R value (logical) from Pulse and Steering Control Unit to

First Stage Receiver Unit and Transmit Unit

* Tx_on signal from Pulse and Steering Control Unit to Transmit

Unit

* Tx_ack signal from Transmit Unit to Pulse and Steering

Control Unit

* Rx_protect from Pulse and Steering Control Unit to Transmit

Unit

* Freq. ctrl signal internal to the Pulse and Steering Control Unit

* Delay ctrl signal internal to the Pulse and Steering Control Unit

* Ampl. ctrl signal internal to the Pulse and Steering Control

Unit

* Phase ctrl signal internal to the Pulse and Steering Control Unit

Note that an exact specification of the signals is TBD and thus

the information in this section may be subject to change.


(53)

EROS control

The EROS control category is comprised of the following

information items(EROS control command signals):

* Test Sub-array start-up signal

* Subsystem prime command

* Subsystem start-up signal

* Subsystem shut-down signal

* TBD…

EROS control signals are sent from EROS to the Subsystem

Managers and enable remote controlling of for example system

start-up and shut-down. The EROS control signals use the Tcl

wire protocol and are sent over the slow Ethernet network. After

receiving an EROS control signal, the subsystem is expected to

behave in some predefined manner.

Note that an exact specification of the signals is TBD and thus

the information in this section may be subject to change.

Measurement data

67 Gb/s stream of measurement data containing the resulting

beams (2x10 beams) from the signal processing of the First Stage

Beamformer.

RF

Radio Frequency signal

Rx

△RF

Received signal.

Status

The Status category is comprised of a number of status signals

containing the status information requested by the Status inquiry

commands.

Status signals are sent from the Subsystem Managers to EROS

and provides the information needed for EROS to determine the

health of the subsystems.

The Status signals use the Tcl wire protocol and are send over

the slow Ethernet network.

Status inquiry

The Status inquiry command category is comprised of the

following information items (status inquiry command signals):

* Excess temperature from Transmit Unit

* Excess reflected power from Transmit Unit

* LNA_V_in

* LNA_I_in

* ADC_I_in


(53)

* ADC_V_in

* Beamformer_I_in

* Beamformer_V_in

* Instrument Container Temperature

* Instrument Container Humidity

* Transmit Unit Operating temperature, T_TU_op

* Anti-aliasing operating temperature, T_AAF_op

* LNA ambient temperature, T_LNA_amb

* Response time, t_re, for subsystem ___

* Component failure, F_comp

* Transmit Unit Storage Temperature, T_storage

* TBD…

Status inquiry commands are sent from EROS to the Subsystem

Managers and enable the overall monitoring of the health of the

Test Sub-array subsystems. The Subsystem Manager receives the

status inquiry command, retrieves the requested information and

then returns it back to EROS through status signals.

The Status inquiry command signals use the Tcl wire protocol

and are sent over the slow Ethernet network.

TBD V

Electric power supply voltage.

Time,

Synchronization

Time signal containing frequency and synchronization (e.g.

pulse-per-second) references used for timekeeping and time

measurement.

Tx signals

△RF

Samples of transmitted signal.


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4.3.2 EROS/Subsystem Manager Message Protocol

EROS communicates with SubMan via a single, configurable network address (IP

address and port number) by using the Tcl wire protocol, see

https://core.tcl.tk/tcllib/doc/trunk/embedded/www/tcllib/files/modules/comm/comm_

wire.html

The general structure of a command from EROS to SubMan is a Unicode UFT-8

encoded string of space-separated words – consisting of command name followed by

flags, options, and command arguments:

command = name parameter parameter …

The command structure is compatible with the standard C library routine getopt. The

Tcl wire protocol embeds the command string into a communication frame,

terminating in the line feed character (UNIX: “\n”). The entire message string

normally has the following structure:

message = { instruction transaction_id { command } } LF

The Tcl wire protocol supports three different instruction words, and SubMan

supports at least two of them: send and async.

instruction = send | async

Send means that SubMan performs the required task and then sends an explicit reply

to the involved EROS client (which is blocked during the execution of the task). Note

that everything described in this section must be carried out according to the Tcl wire

protocol.

Async means that SubMan performs the required task but it will not send a reply of

any kind and the involved EROS client will not be blocked and is proceeding

immediately after sending its command to SubMan. The async command may for

example be used to launch a long-living action in the subsystem.

https://core.tcl.tk/tcllib/doc/trunk/embedded/www/tcllib/files/modules/comm/comm_wire.html




(53)

5 Requirements Allocation

Requirements and requirement allocation are found in the Technical Specification for

each subsystem.


(53)

6 Notes

The diagrams in this document are created using SysML modeling language. The

diagram presents a view of the system or subsystem and may not display all of the

information that is available in the underlying system or subsystem model.

6.1 Description of Diagrams

In this document both structural and behavioral diagrams are included.

In structural diagrams, the different subsystems and components are represented by

rectangles that each displays the type of system, the name of that instance, as well as

any subsystems (parts) that are of contextual importance. A diagram can also display

the interactions between the systems and these interactions are represented by lines.

The lines can be arrowed which displays the direction of the flow (that composes the

interaction, e.g. flows of information, matter, etc.) and the type of flow (for example

“control” if control signals are sent between some systems) may also be displayed.

The diagram below exemplifies a number of different items that can appear on a

structural diagram, as described in the previous paragraph. External interfaces, if

displayed, are represented by small squares on the diagram edges of the subsystems.

Activity diagrams are used to specify behaviors, with a focus on the flow of control

and the transformation of inputs into outputs through a sequence of actions. Activity

partitions (visualized as the vertical ”swimlanes” on the diagrams) enable you to

allocate system behaviors to system structures (for example subsystems and users),

i.e. displaying who will do what in which order.

The arrows represent the flow between the different actions (“subactivities” or tasks)

of the activity. On the activity diagrams in this SSDD, the flows simply indicate

which action is currently enabled during the execution of the activity. Activity

diagrams express the order in which actions are performed as well as which structure

performs each action, but they do not offer any mechanism to express which structure

invokes each action.

In summary, the activity diagram can be said to provide a dynamic view of the system

that displays sequences of system tasks or activities that will be carried out, as well as

the general flow between these activities over time. [SysML]


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Diagram 21: Interpretation of structural diagrams

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