Ronja(Reasonable Optical Near Joint Access) Report

8/10/2019 Ronja(Reasonable Optical Near Joint Access) Report

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RONJA

(Reasonable Optical Near Joint Access)

A Seminar Report

Submitted by

RAGHAVENDRA.S.RAO

in partial ful fi lment for the award of the degree

of

BACHELOR OF TECHNOLOGY

IN

ELECTRONICS AND TELECOMMUNICATION

Guided by

Mr. B.B.WATTAMWAR

At

MAHARASHTRA INSTITUTE OF TECHNOLOGY

AURANGABAD

2013-14


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CERTIFICATE

This is to certify that, the report RONJA (Reasonable Optical Near Joint Access)

submitted by

Raghavendra.S.Rao

is a bonafide work completed under my supervision and guidance in partial fulfilment for

award of Bachelor Of Technology (Electronics and Telecommunication) Degree of

Maharashtra Institute Of Technology Aurangabad.

Place : Aurangabad

Date :

Dr. S. P. Bhosle

Principal

Maharashtra Institute Of Technology Aurangabad

Mr. B.B.Wattamwar

Guide

Mrs. V. M. Kulkarni

Head of the Department


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TABLE OF CONTENTS

CHAPTER TITLE PAGE

ABSTRACT 4

ACKNOWLEDGMENT

LIST OF ABBREVIATIONS

5

6

I INTRODUCTION

1.1 Introduction 7

1.2 Necessity and objectives 8

1.3 Theme and Organisation 9

II LITERATURE SURVEY

2.1 Point-to-Point Protocol (PPP) 10

2.2 Free Space Vs Radio 13

2.3 Optics 14

2.4 Signals 15

2.5 LED Vs Laser 24

III SYSTEM DEVELOPMENT

3.1 General Scrutiny 26

3.2 Block diagram and its Description

3.3 Models and their specifications

28

39

IV CONCLUSION

4.1 Applications and Future Scope 45

4.2 Pros & Cons 47

V REFERENCES 48


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ABSTRACT

RONJA (Reasonable Optical Near Joint Access)Allows one to make a free

space 10Mbps full-duplex Ethernet bridge between two points up to 1.4 km

away using visible incoherent light.

The transmitter sends a signal with a Light Emitting Diode (LED), the light rays

are collimated (paralleled) by a lens. On the other side of the bridge the receiver

uses another lens to focus light onto a photo diode. The Twister is the

electronics that cleans up the signal, adds a pulse when no data is being

communicated, and adds the link integrity pulse back to the Ethernet cable. The

pulse is used to keep the Receiver knowing what a signal is over noise.

This report covers the basic introduction to RONJA, Scrutiny of its system

functioning, advantages of RONJA along with its future improvements and

scopes.


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ACKNOWLEDGEMENT

I wish to express my deep gratitude and appreciation for the invaluable guidance of our

professors throughout the span of preparing this seminar. We are indebted to our college

Principal Dr. S. P. Bhosle.

I am also thankful to our HOD Mrs. V. M. Kulkarni and my Seminar Guide

Mr.B.B.Wattamwar for his precious and elaborate suggestions. Their excellent guidance

made me to complete this task successfully within a short duration.

The inspiration behind the every aspect of life constructs a way to get success, which I

have got from all the professors of the department.

No thanks giving would be complete without mentioning my parents and family

members, without their constant support and encouragement, this assignment wouldnt have

been successful.

RAGHAVENDRA.S.RAO


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LIST OF ABBREVIATIONS

SONET-Synchronous Optical Networking

ISP-Internet Service Provider

NBF-NetBIOS Frames protocol

DECnet-Digital Equipment CorporationNetworks

IPCP-IP Control Protocol

SSl-Secure Sockets Layer

SSH-Secure Shell

L2TP-Layer 2 Tunneling Protocol IEEE-Institute of Electrical and Electronics Engineers

FCC-Federal Communications Commission

ASCII-American Standard Code for Information Interchange

RX-Receiver

TX-Transmitter

PCB-Printed Circuit board

HDLC-High-Level Data Link Control

ADCCP-Advanced Data Communication Control Procedures

LAN-Local Area Network

LLC-Logical Link Control

MAC-Media Access Control

CSMA/MD-Carrier Sense Multiple Access with Collision Detection
http://en.wikipedia.org/wiki/Digital_Equipment_Corporationhttp://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/Digital_Equipment_Corporation


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INTRODUCTION

RONJAis afree-space optical communication system which transmits datawirelessly using

beams oflight.Ronja can be used to create a 10 Mbit/sfull duplexEthernetpoint-to-point

link, having a range of 1.4 km, through an optoelectronic device you can mount on your

house and connect your PC, home or office network with other network.

The device consists of a receiver andtransmitterpipe (optical head) mounted on a sturdy

adjustable holder. Twocoaxial cables are used to connect the rooftop installation with a

protocol translator installed in the house near acomputer orswitch.The range can be

extended to 1.9 km (1.2 mi) by doubling or tripling the transmitter pipe.

A complete RONJA system is made up of 2transceivers:2 opticaltransmitters and 2opticalreceivers.They are assembled individually or as a combination. The complete system

layout is shown in theblock diagram above.

The range of the basic configuration is 1.4 km (0.9 miles).

.
http://en.wikipedia.org/wiki/Free-space_optical_communicationhttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Full_duplexhttp://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Coaxial_cablehttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Transceivershttp://en.wikipedia.org/wiki/Transmittershttp://en.wikipedia.org/w/index.php?title=Optical_receiver&action=edit&redlink=1http://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/w/index.php?title=Optical_receiver&action=edit&redlink=1http://en.wikipedia.org/wiki/Transmittershttp://en.wikipedia.org/wiki/Transceivershttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Coaxial_cablehttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Full_duplexhttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Free-space_optical_communication


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NECESSITY AND OBJECTIVES

The Foundation of any Project lies in its need which defines its existence. In Todays Era of

Wireless Communication, there is an emerging trend which appeals the use of optical energy

to transfer information. Moreover, in it, the most efficient, most advantageous and secure

systems are preferred. Ronja is amongst those systems which can easily cater to all these

needs. The Demands of Full Duplex, high Speed, Energy efficient and point-to-point secure

transmission can be efficiently fulfilled by RONJA, thus proving its necessity and Objectives.


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THEME AND ORGANISATION

Ronja has a Theme of Pure Optical Communication in Synergy with Networking, associated

with it. It is all concerned about the transmission and reception of data within the boundaries

defined by its Design and Structural capabilities obeying all the necessary Protocols. Twilight

laboratories, Prague, Czech Republic, is the organization which is associated with RONJA


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LITERTURE SURVEY

Point-to-Point Protocol:

Point-to-Point Protocol (PPP) is adata linkprotocol used to establish a direct connection

between twonodes.It can provide connectionauthentication,transmissionencryption and

compression.

PPP is used over many types of physical networks includingserial cable,phone line,trunk

line,cellular telephone,specialized radio links, and fiber optic links such asSONET.PPP is

also used overInternet access connections.Internet service providers (ISPs) have used PPP

for customerdial-up access to theInternet,since IP packets cannot be transmitted over a

modem line on their own, without some data link protocol. Two derivatives of PPP,Point-to-Point Protocol over Ethernet (PPPoE) andPoint-to-Point Protocol over ATM (PPPoA), are

used most commonly by Internet Service Providers (ISPs) to establish aDigital Subscriber

Line (DSL) Internet service connection with customers.

PPP is commonly used as adata link layerprotocol for connection oversynchronous and

asynchronous circuits,where it has largely superseded the olderSerial Line Internet Protocol

(SLIP) and telephone company mandated standards (such asLink Access Protocol, Balanced

(LAPB) in theX.25protocol suite). The only requirement for PPP is that the circuit provided

beduplex.PPP was designed to work with numerousnetwork layerprotocols, including

Internet Protocol (IP),TRILL,Novell'sInternetwork Packet Exchange (IPX),NBF,DECnet

andAppleTalk.

PPP permits multiple network layer protocols to operate on the same communication link.

For every network layer protocol used, a separate network control protocol (NCP) is provided

in order to encapsulate and negotiate options for the multiple network layer protocols. It

negotiates network-layer information, e.g. network address or compression options, after the

connection has been established.

For example, Internet Protocol (IP) uses the IP Control Protocol (IPCP), and Internetwork

Packet Exchange (IPX) uses the Novell IPX Control Protocol (IPX/SPX). NCPs include

fields containing standardized codes to indicate the network layer protocol type that the PPP

connection encapsulates.

The phases of the Point to Point Protocol according are listed below:
http://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Protocol_%28computing%29http://en.wikipedia.org/wiki/Node_%28networking%29http://en.wikipedia.org/wiki/Authenticationhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Data_compressionhttp://en.wikipedia.org/wiki/Serial_cablehttp://en.wikipedia.org/wiki/Phone_linehttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Cellular_telephonehttp://en.wikipedia.org/wiki/SONEThttp://en.wikipedia.org/wiki/Internet_accesshttp://en.wikipedia.org/wiki/Internet_service_providerhttp://en.wikipedia.org/wiki/Dial-up_accesshttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_ATMhttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Data_link_layerhttp://en.wikipedia.org/wiki/Synchronous_circuithttp://en.wikipedia.org/wiki/Asynchronous_circuithttp://en.wikipedia.org/wiki/Serial_Line_Internet_Protocolhttp://en.wikipedia.org/wiki/LAPBhttp://en.wikipedia.org/wiki/X.25http://en.wikipedia.org/wiki/Duplex_%28telecommunications%29http://en.wikipedia.org/wiki/Network_layerhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/TRILL_%28computing%29http://en.wikipedia.org/wiki/Internetwork_Packet_Exchangehttp://en.wikipedia.org/wiki/NetBIOS_Frames_protocolhttp://en.wikipedia.org/wiki/DECnethttp://en.wikipedia.org/wiki/AppleTalkhttp://en.wikipedia.org/wiki/IPCPhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPCPhttp://en.wikipedia.org/wiki/AppleTalkhttp://en.wikipedia.org/wiki/DECnethttp://en.wikipedia.org/wiki/NetBIOS_Frames_protocolhttp://en.wikipedia.org/wiki/Internetwork_Packet_Exchangehttp://en.wikipedia.org/wiki/TRILL_%28computing%29http://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Network_layerhttp://en.wikipedia.org/wiki/Duplex_%28telecommunications%29http://en.wikipedia.org/wiki/X.25http://en.wikipedia.org/wiki/LAPBhttp://en.wikipedia.org/wiki/Serial_Line_Internet_Protocolhttp://en.wikipedia.org/wiki/Asynchronous_circuithttp://en.wikipedia.org/wiki/Synchronous_circuithttp://en.wikipedia.org/wiki/Data_link_layerhttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_ATMhttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Dial-up_accesshttp://en.wikipedia.org/wiki/Internet_service_providerhttp://en.wikipedia.org/wiki/Internet_accesshttp://en.wikipedia.org/wiki/SONEThttp://en.wikipedia.org/wiki/Cellular_telephonehttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Phone_linehttp://en.wikipedia.org/wiki/Serial_cablehttp://en.wikipedia.org/wiki/Data_compressionhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Authenticationhttp://en.wikipedia.org/wiki/Node_%28networking%29http://en.wikipedia.org/wiki/Protocol_%28computing%29http://en.wikipedia.org/wiki/Data_Link_Layer


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Link Dead: This phase occurs when the link fails, or one side has been told to disconnect (e.g.

a user has finished his or her dialup connection.)

Link Establishment Phase: This phase is where Link Control Protocol negotiation is

attempted. If successful, control goes either to the authentication phase or the Network-Layer

Protocol phase, depending on whether authentication is desired.

Authentication Phase: This phase is optional. It allows the sides to authenticate each other

before a connection is established. If successful, control goes to the network-layer protocol

phase.

Network-Layer Protocol Phase: This phase is where each desired protocols'Network Control

Protocols are invoked. For example,IPCP is used in establishing IP service over the line.

Data transport for all protocols which are successfully started with their network control

protocols also occurs in this phase. Closing down of network protocols also occur in this

phase.

Link Termination Phase: This phase closes down this connection. This can happen if there is

an authentication failure, if there are so many checksum errors that the two parties decide to

tear down the link automatically, if the link suddenly fails, or if the user decides to hang up

his connection.
http://en.wikipedia.org/wiki/Network_Control_Protocolhttp://en.wikipedia.org/wiki/Network_Control_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocol_Control_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocol_Control_Protocolhttp://en.wikipedia.org/wiki/Network_Control_Protocolhttp://en.wikipedia.org/wiki/Network_Control_Protocol


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Many protocols can be used totunnel data over IP networks. Some of them, likeSSL,SSH,

orL2TP create virtualnetwork interfaces and give the impression of a direct physical

connections between the tunnel endpoints. On aLinux host for example, these interfaces

would be called tun0.

As there are only two endpoints on a tunnel, the tunnel is a point-to-point connection and PPP

is a natural choice as a data link layer protocol between the virtual networks interfaces. PPP

can assign IP addresses to these virtual interfaces, and these IP addresses can be used, for

example, to route between the networks on both sides of the tunnel.
http://en.wikipedia.org/wiki/Tunneling_protocolhttp://en.wikipedia.org/wiki/Secure_Sockets_Layerhttp://en.wikipedia.org/wiki/Secure_Shellhttp://en.wikipedia.org/wiki/L2TPhttp://en.wikipedia.org/wiki/Network_interfacehttp://en.wikipedia.org/wiki/Linuxhttp://en.wikipedia.org/wiki/Linuxhttp://en.wikipedia.org/wiki/Network_interfacehttp://en.wikipedia.org/wiki/L2TPhttp://en.wikipedia.org/wiki/Secure_Shellhttp://en.wikipedia.org/wiki/Secure_Sockets_Layerhttp://en.wikipedia.org/wiki/Tunneling_protocol


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Free Space vs. Radio

Radio (Such as IEEE 802.11) can also be used to create a network bridge. Free Space Optics

have some advantages and disadvantages compared to Radio.

1. Eavesdropping

Because of the nature of radio waves, it is harder to contain where the radio waves go, even

in directional point to point networks a signal can still be eavesdropped over a large area. For

example a typical parabolic antenna has a beam width of 16, at 1.4km one would still be

able to receive the signal 194 meters on either side of where it is pointing. The signal can also

be listened to behind the intended location. With a free space network you must intercept the

light beam, this is much more difficult and can be detected.

2. Interference

Radio waves can interfere with each other. This interference is one of the reasons the FCC

licenses spectrum. There are blocks of spectrum free to use, but other devices are also using

them. As an example if you used the public block in the 2.4GHz range, your signal can get

interference from portable phones, wireless access points, microwave ovens, car alarms, and

security cameras. This can make your signal less dependable.

Free space optic networks are free from these types of interference.

3. Distance

Radio waves have improved distance over free space optics. Free space optics is limited to

how far it can travel through the atmosphere because of absorption.

4. Fresnel Zones

The Fresnel zone of light is very small compared to radio waves. If there is an obstruction in

the first Fresnel zone it will produce interference.


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Optics

Geometric:

The RONJA uses a double convex spherical lens, which is typical found in magnifying

glasses. As shown in Figure 2, the RONJA uses the lens to take light from a LED and

collimate it, as well as take incoming light into a point.

The Transmitter side takes light from a LED and it will collimate it towards the Receiver

side.

The Receiver will take incoming parallel light and will focus it into a point using a double

Convex Lens.


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Signals

Information in a computer is stored as a set of hi/lo values or binary. For example, an ASCII

a is represented as 01100001. This can be communicated as two sets of different voltages,

or like in the RONJA blink on and blink off. There are many ways to encode the information

to make it more resistant to noise or to make sure that timings are synchronized. The next

subsections go over some of the encodings used in Ethernet 10BASE-T and 100BASE-TX.

The RONJA currently supports 10BASE-T.

NRZ Encoding

NRZ (Non-Return to Zero) is a simple encoding, hi for 1 and lo for 0, each bit delimited by

time (See Figure 6). In NRZ, clock timing is important and is often used internally when

everything is operating off the same clock. Imagine a long stream of 1s there would not be

any indication of how to set your clock between bits. If this information is sent to another

system that has a slightly different clock, it could easily become out of sync.


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Manchester Encoding

An Ethernet 10Base-T network sends its data in a Manchester encoding. A property of the

Manchester encoding is that it needs twice the bandwidth of the data com-pared to NRZ, thus

a response capable of 10 MHz is needed (1 Hz/bit). Our LED and photo diode are capable of

handling these response times.

Encoding a Data Byte:

Encoding is the process of adding the correct transitions to the message signal in relation to

the data that is to be sent over the communication system. The first step is to establish the

data rate that is going to be used. Once this is fixed, then the mid-bit time can be determinedas of the data rate period. In our example we are going to use a data rate of 4 kHz. This

provides a bit period of 1/f = 1/4000 = 0.00025s or 250 s. Dividing by two gives us the mid-

bit time (which we will label T) of 125 s. Now let's look at how we use this to encode a

data byte of 0xC5 (11000101b). The easiest method to do this is to use a timer set to expire or

interrupt at the T interval. We also need to set up a method to track which bit period we are

currently sending. Once we do this, we can easily encode the data and output the message

signal.

1. Begin with the output signal high.

2. Check if all bits have been sent, If yes, then go to step 7

3. Check the next logical bit to be coded

4. If the bit equals 1, then call ManchesterOne(T)

5. Else call ManchesterZero(T)


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6. Return to step 2

7. Set output signal high and return

Implementation of ManchesterOne(T)

1. Set the output signal low

2. Wait for mid-bit time (T)

3. Set the output signal high


5. Return

Implementation of ManchesterZero(T)

6. Set the output signal high


8. Set the output signal low


10. Return

These easy routines will provide an output at the microcontroller pin that exactly encodes the

data into a Manchester message signal at the desired data rate. The accuracy of the data rate

and duty cycle depends on the accuracy of the clock source and the method used to create the

wait times.


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Manchester Decoding

Decoding is where most people attempting to work with Manchester have questions. There

are several ways to approach this and each has unique benefits. This section will describe

how to implement two different methods. To start we will look at the steps that are needed for

either methodology.

1. The data rate clock must be either known or discovered (we will assume a known value)

2. We must synchronize to the clock (distinguish a bit edge from a mid-bit transition)

3. Process the incoming stream and recover the data using the previous two steps.

4. Buffer or store this data for further processing.

This provides the basic outline for how we will perform Manchester decoding. All that

remains is to implement this in software. As mentioned, we have two different options for

consideration.

One is based on timing while the other utilizes sampling.


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Timing Based Manchester Decode

In this approach we will capture the time between each transition coming from the

demodulation circuit. The Input Capture function on a micro-controller is very useful for this

because it will generate an interrupt, precise time measurements, and allow decision

processing based on the elapsed counter value.

1. Set up timer to interrupt on every edge (may require changing edge trigger in the ISR)

2. ISR routine should flag the edge occurred and store count value

3. Start timer, capture first edge and discard this.

4. Capture next edge and check if stored count value equal 2T (T = data rate)

5. Repeat step 4 until count value = 2T (This is now synchronized with the data clock)

6. Read current logic level of the incoming pin and save as current bit value (1 or 0)

7. Capture next edge

a. Compare stored count value with T

b. If value = T

i. Capture next edge and make sure this value also = T (else error)

ii. Next bit = current bit

iii. Return next bit

c. Else if value = 2T

i. Next bit = opposite of current bit

ii. Return next bit

d. Else

i. Return error

8. Store next bit in buffer

9. If desired number of bits are decoded; exit to continue further processing

10. Else set current bit to next bit and loop to step 7


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MLT-3(multi-level transmit)

MLT-3 is a encoding used in Ethernet 100BASE-TX. It changes from its current state to the

next every time there is a high. It has 3 states: typically positive, zero, and negative. A reason

to use this encoding is to reduce the frequency by four (one cycle: hi-med-lo-med) compared

to something like Manchester. This makes it easy to be transferred in copper cable. It reduces

the frequency traveling through copper cable for the 100BASE-TX to 31.25 MHz. This is of

no help in reducing the frequency when you have only two states on and off. Creating a third

state with the LED alone (such as half intensity), would reduce the range.


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BiPhase

BiPhase adds a level of complexity to the coding process but in return includes a way to

transfer the bit frame data clock that can be used in the decoding to increase accuracy.

BiPhase coding says that there will be a state transition in the message signal at the end of

every bit frame. In addition, a logical 1 will have an additional transition at the mid-bit.


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Modulation

Modulation refers to the act of adding the message signal to some form of carrier. The carrier,

by definition, is a higher frequency signal whose phase, frequency, amplitude, or some

combination thereof, is varied proportionally to the message. This change can be detected and

recovered (demodulated) at the other end of the communication channel. There are a number

of ways this can be done but for simplicity we will only look at Amplitude Modulation (AM),

On-Off Keying (a variation on AM), and Frequency Modulation (FM). Modulation is

typically carried out in hardware.

Amplitude Modulation

In amplitude modulation, the amplitude of the carrier is changed to follow the message

signal. In this case we can see a ripple on the carrier, its envelope contains the message.

This can be demodulated using an extremely simple envelope detector that captures this

ripple as a low frequency response.


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On-Off Keying

This form of modulation takes the amplitude modulation as described above to the extreme.

In this instance, we have only two states: Carrier and No Carrier. This approach lends itself

nicely to the transmission of digital data because the carrier can be simply switched on or

off depending on the state of the data being sent. The demodulated output is either high or

low depending on the presence of the carrier.

Frequency Modulation

Frequency modulation is more complicated but provides the benefit of constant output power

independent of the message being sent. With this approach, the frequency of the carrier is not

constant but varies in relation to the message. This requires a much more complicated

demodulation circuit typically implemented using a Phase Lock Loop (PLL).


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LED vs LASER

A common response to those introduced to the RONJA is that a LASER should be used

instead of a LED. This section will try to compare a LASER vs LED.

1 Response Time

The LASER has an advantage of shorter response times than the LED. The LASER diode is

stimulated to emit instead of spontaneous like the LED. LASER diodes with less than 1ns

(1Ghz) response times are available. It is hard to find diodes with less than 20ns (50Mhz)

response times. The LED response time works fine for the RONJA(10Mhz), if we wanted to

make a faster link, this is where the LASER could have an advantage.

2 Monochromatic

A LASER tends to emit a beam more monochromatic ( 24nm

FWHM), it makes it easier to add filters to the optics to only allow the light from the LASER

wavelength reducing ambient noise, and possibility of photo diode saturation from outside

sources. There are also disadvantages, because of the narrow wavelengths emitted by the

laser there could be conditions where that wavelength is absorbed, such as certain ice crystals

in the air that absorb certain narrow bands of wavelength. With the LED you are emitting a

much broader set of wavelengths. If some of it gets absorbed, you still have the rest to fall

back on.

3 Scintillation

Scintillation can be far worse for a LASER than the LED because the LASER is more

coherent than the LED. As the beam travels through the air, it will hit packets of air of

different temperature which have adifferent index of refraction causing constructive and

destructive interference which can ruin your signal. This effect can be especially bad

depending on the terrain it travels over. Asphalt, ponds, fountains, all create temperature

differences that will contribute to scintillation.


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4 Safety

LASERs can be dangerous. Devices sold to the market place that contain lasers must go

through the FDA. Even low powered lasers should have extra safety precautions such as auto

shutoff if there is a beam break. For lasers rated higher than IIIa/3R protective eye goggles

are needed when working with them. Even light reflected after it has hit a object can be

enough to damage the eye depending on the power and wavelength of the LASER.


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SYSTEM DEVELOPMENT

General Scrutiny

One Ronja device is a single long-distance optical transceiver that is capable of runningagainst the same or compatible device on the other side of the link. The topology is point-to-

point.

Building a Ronja is rather lenghty job (this will hopefully change in future) that however

pays off in a reliable and performant device that is capable of delivering steady connectivity

with little maintenance and can be run freely without a need of authorities' approval. Also a

possibility of interference and eavesdropping is negligible. Dropouts are infrequent and

determined solely by weather and are thus foreseeable.

He who wants to enjoy the adrenaline sport of driving primitive retail parts into flawless

cooperation to provide the uncurbed full duplex connectivity experience must withstand these

nuisances:

Ronja is somewhat labor expensive. Things have been made much easier by putting

the most complicated electronics on a PCB. The cost of parts is negligible in

comparison with the labor, for example the components for the whole Ronja 10M

Metropolis cost just 1500CZK. Further reduction in labor demands is planned by

putting RX and TX on PCB too.

The user must possess certain basic manual skills as soldering, drilling, painting, and

technical drawing/schematic reading. But people without any previous experience

with soldering have built a piece that worked on the first try!


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The user must not cut the corners during the building

Butthere are also certain conveniences:

The parts are chosen to be of the widest availability possible and equivalents are

provided where applicable

Innovative approach is used to speed up the work and make it convenient. Sector

codes are present to make the population easy. Drilling is simplified by drilling

templates - just print and no measurement is necessary in the workshop!

The device is based on the KISS rule (Keep It Simple, Stupid) which makes the

device plug-and-play immediately after the building provided the user hasn't botched

anything.

The design is rugged and over dimensioned to withstand variations in the

components. As a consequence, the resulting device is rock solid in steady

performance and provides outstanding electromagnetic interference immunity and

electromagnetic compatibility. Withstands -20C as well as direct sunlight and heat

with obvious margin. During a lightning storm, lightning strike in proximity usually

doesn't generate even a single lost bit.

In case of device failure (direct lightning strike), the measuring points can be

inspected and bad components replaced without a need to throw the whole device out.


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gates. Therefore the 74AC04 is operating as a structured powerCMOSswitch completely in

analog mode.

This way the LEDjunctionis flooded and cleared ofcarriersas quickly as possible, basically

byshort circuitdischarge. This pushes the speed of the LED to maximum, which makes the

output optical signal fast enough so that the range/power ratio is the same as with the faster

red HPWT-BD00-F4000 LED. The side effects of this brutal driving technique are: 1) the

LED overshoots at the beginning of longer (5 MHz/1 MHz) impulses to about 2x brightness.

This was measured to have no adverse effect on range. 2) A blockingceramic capacitorbank

backing up the 74AC04 switching array is crucial for correct operation, because charging and

discharging the LED is done by short circuit. Under dimensioning this bank causes the

leading and trailing edges of the optical output to grow longer.
http://en.wikipedia.org/wiki/CMOShttp://en.wikipedia.org/wiki/CMOShttp://en.wikipedia.org/wiki/CMOShttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/CMOS


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Optical Receiver - Preamplifier stage:

The usual approach in FSO (Free Space Optics)preamplifiersis to employ atransimpedance

amplifier.A transimpedance amplifier is a very sensitivebroadbandhigh-speed device

featuring afeedback loop.

Following is the brief scrutiny of a transimpedance amplifier:

The transimpedance amplifier as shown above presents a low impedance to the photodiode

and isolates it from the output voltage of the operational amplifier. In its simplest form a

transimpedance amplifier has just a large valued feedback resistor, Rf. The gain of the

amplifer is set by this resistor and because the amplifier is in an inverting configuration, has a

value of -Rf. There are several different configurations of transimpedance amplifiers, each

suited to a particular application. The one factor they all have in common is the requirement

to convert the low-level current of a sensor to a voltage. The gain, bandwidth, as well as

current and voltage offsets change with different types of sensors, requiring different

configurations of transimpedance amplifiers.

This transimpedance amplifier inside a ronja system also makes use of a PIN diode.

A PIN diode is adiode with a wide, undopedintrinsic semiconductor region between ap-type

semiconductor and ann-type semiconductor region. The p-type and n-type regions are

typically heavilydopedbecause they are used forohmic contacts.A PIN diode operates

under what is known as high-level injection. In other words, the intrinsic "i" region is flooded

with charge carriers from the "p" and "n" regions.
http://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Intrinsic_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/N-type_semiconductorhttp://en.wikipedia.org/wiki/Doping_%28semiconductor%29http://en.wikipedia.org/wiki/Ohmic_contacthttp://en.wikipedia.org/wiki/Ohmic_contacthttp://en.wikipedia.org/wiki/Doping_%28semiconductor%29http://en.wikipedia.org/wiki/N-type_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/Intrinsic_semiconductorhttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Preamplifier


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Its function can be likened to filling up a water bucket with a hole on the side. Once the water

reaches the hole's level it will begin to pour out. Similarly, the diode will conduct current

once the flooded electrons and holes reach an equilibrium point, where the number of

electrons is equal to the number of holes in the intrinsic region. When the diode is forward

biased, the injected carrier concentration is typically several orders of magnitude higher than

the intrinsic level carrier concentration. Due to this high level injection, which in turn is due

to thedepletion process,the electric field extends deeply (almost the entire length) into the

region. This electric field helps in speeding up of the transport of charge carriers from P to N

region, which results in faster operation of the diode, making it a suitable device for high

frequency operations.

Ronja however uses a feedback-less design where the PIN has a high workingelectrical

resistance(100kilohms)which together with the total input capacitance (roughly 7 pF, 5 pF

PIN and 2 pF inputMOSFETcascade)makes the device operate with apassbandon a 6

dB/oct slope of low pass formed by PIN working resistance and total input capacitance. The

signal is then immediately amplified to remove the danger of contamination bysignal noise,

and then a compensation of the 6 dB/oct slope is done by derivator element on the

programming pins of an NE592 video amplifier. The NE592 video amplifier is a monolithic,

two-stage, differential output, and wideband video amplifier. It offers fixed gains of 100 and

400 without external components and adjustable gains from 400 to 0 with one external

resistor. The input stage is designed so that with the addition of a few external reactive

elements between the gain select terminals, the circuit can function as a high-pass, low-pass,

or band-pass filter.
http://en.wikipedia.org/wiki/Depletion_regionhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/MOSFEThttp://en.wikipedia.org/wiki/MOSFEThttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/MOSFEThttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Depletion_region


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This feature makes the circuit ideal for use as a video or pulse amplifier in

communications, magnetic memories, display, video recorder systems, and floppy

disk head amplifiers. It is available in an 8-pin version with fixed gain of 400 without

external components and adjustable gain from 400 to 0 with one external resistor.

Due to this implementation, a surprisingly flat characteristic is obtained in the

receiver section of the RONJA. If the PIN diode is equipped with 3 kworking

resistor to operate in flat band mode, the range is reduced to about 30% due tothermal

noisefrom the 3 k resistor.
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Transceiver - Ronja Twister:

An optical transceiver module configured for long wave optical transmission is disclosed.

Significantly, the transceiver module utilizes components formerly used only for shortwave

optical transmission, thereby reducing new component production and device complexity. Inone embodiment, the transceiver module includes a transmitter optical subassembly including

a laser capable of producing an optical signal. A consolidated laser driver/post amplifier

including a first bias current source provides a bias current to the laser for producing the

optical signal. A means for amplifying the bias current provided to the laser by the first bias

current source is also included as a separate component from the laser driver/post amplifier.

The means for amplifying in one embodiment is a field-effect transistor that is operably

connected to the laser driver/post amplifier and configured to provide an additional bias

current to the laser diode such that sufficient lasing operation of the laser is realized.


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Physical Layer:

In the seven-layerOpen Systems Interconnection model (OSI) ofcomputer networking,the

physical layer or layer 1 is the first (lowest) layer. The implementation of this layer is often

termed PHY. The physical layer consists of the basicnetworking hardware transmission

technologies of anetwork.It is a fundamental layer underlying the logical data structures of

the higher level functions in a network. Due to the plethora of available hardware

technologies with widely varying characteristics, this is perhaps the most complex layer in

the OSI architecture. The physical layer defines the means of transmitting raw bits rather than

logicaldata packets over a physicallink connectingnetwork nodes.Thebit stream may be

grouped into code words or symbols and converted to a physicalsignal that is transmitted

over a hardwaretransmission medium.The physical layer provides an electrical, mechanical,and procedural interface to the transmission medium.

The major functions and services performed by the physical layer are:

Bit-by-bit orsymbol-by-symbol delivery

Providing a standardized interface to physicaltransmission media,including

Mechanical specification ofelectrical connectors andcables,for example maximum

cable length

Electrical specification oftransmission linesignal level andimpedance

Radio interface, includingelectromagnetic spectrumfrequency allocation and

specification ofsignal strength,analogbandwidth,etc.
http://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Networking_hardwarehttp://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Network_packethttp://en.wikipedia.org/wiki/Data_linkhttp://en.wikipedia.org/wiki/Network_nodehttp://en.wikipedia.org/wiki/Bit_streamhttp://en.wikipedia.org/wiki/Signal_%28electronics%29http://en.wikipedia.org/wiki/Transmission_mediumhttp://en.wikipedia.org/wiki/Symbol_%28data%29http://en.wikipedia.org/wiki/Transmission_mediahttp://en.wikipedia.org/wiki/Electrical_connectorhttp://en.wikipedia.org/wiki/Cablehttp://en.wikipedia.org/wiki/Transmission_linehttp://en.wikipedia.org/wiki/Signal_levelhttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Frequency_allocationhttp://en.wikipedia.org/wiki/Signal_strengthhttp://en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29http://en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29http://en.wikipedia.org/wiki/Signal_strengthhttp://en.wikipedia.org/wiki/Frequency_allocationhttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Signal_levelhttp://en.wikipedia.org/wiki/Transmission_linehttp://en.wikipedia.org/wiki/Cablehttp://en.wikipedia.org/wiki/Electrical_connectorhttp://en.wikipedia.org/wiki/Transmission_mediahttp://en.wikipedia.org/wiki/Symbol_%28data%29http://en.wikipedia.org/wiki/Transmission_mediumhttp://en.wikipedia.org/wiki/Signal_%28electronics%29http://en.wikipedia.org/wiki/Bit_streamhttp://en.wikipedia.org/wiki/Network_nodehttp://en.wikipedia.org/wiki/Data_linkhttp://en.wikipedia.org/wiki/Network_packethttp://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Networking_hardwarehttp://en.wikipedia.org/wiki/Computer_network


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Specifications forIR overoptical fiber or a wireless IR communication link

Modulation

Line coding

Bit synchronization in synchronousserial communication

Start-stop signaling andflow control inasynchronous serial communication

Circuit switching

Multiplexing

Establishment and termination ofcircuit switched connections

Carrier sense andcollision detection utilized by some level 2multiple access

protocols

Equalization filtering,training sequences,pulse shaping and othersignal processing

of physical signals

Forward error correction for example bitwise convolutional coding

Bit-interleaving and otherchannel coding
http://en.wikipedia.org/wiki/Infrared_radiationhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Line_codinghttp://en.wikipedia.org/wiki/Bit_synchronizationhttp://en.wikipedia.org/wiki/Serial_communicationhttp://en.wikipedia.org/wiki/Start-stop_signallinghttp://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/Asynchronous_serial_communicationhttp://en.wikipedia.org/wiki/Circuit_switchinghttp://en.wikipedia.org/wiki/Multiplexinghttp://en.wikipedia.org/wiki/Circuit_switchedhttp://en.wikipedia.org/wiki/Carrier_sensehttp://en.wikipedia.org/wiki/CSMA/CDhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/Equalizationhttp://en.wikipedia.org/wiki/Training_sequencehttp://en.wikipedia.org/wiki/Pulse_shapinghttp://en.wikipedia.org/wiki/Signal_processinghttp://en.wikipedia.org/wiki/Forward_error_correctionhttp://en.wikipedia.org/wiki/Bit-interleavinghttp://en.wikipedia.org/wiki/Channel_codinghttp://en.wikipedia.org/wiki/Channel_codinghttp://en.wikipedia.org/wiki/Bit-interleavinghttp://en.wikipedia.org/wiki/Forward_error_correctionhttp://en.wikipedia.org/wiki/Signal_processinghttp://en.wikipedia.org/wiki/Pulse_shapinghttp://en.wikipedia.org/wiki/Training_sequencehttp://en.wikipedia.org/wiki/Equalizationhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/CSMA/CDhttp://en.wikipedia.org/wiki/Carrier_sensehttp://en.wikipedia.org/wiki/Circuit_switchedhttp://en.wikipedia.org/wiki/Multiplexinghttp://en.wikipedia.org/wiki/Circuit_switchinghttp://en.wikipedia.org/wiki/Asynchronous_serial_communicationhttp://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/Start-stop_signallinghttp://en.wikipedia.org/wiki/Serial_communicationhttp://en.wikipedia.org/wiki/Bit_synchronizationhttp://en.wikipedia.org/wiki/Line_codinghttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Infrared_radiation


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Data link layer:

The data link layer is the protocol layer that transfers data between adjacent network nodes in

wide area network or between nodes on the samelocal area networksegment.The data link

layer provides the functional and procedural means totransfer data between network entities

and might provide the means to detect and possibly correct errors that may occur in the layer.

Examples of data link protocols areEthernet for local area networks (multi-node), thePoint-

to-Point Protocol (PPP),HDLC andADCCP for point-to-point (dual-node) connections. The

data link layer is concerned with local delivery offramesbetween devices on the same LAN.

Data-link frames, as theseprotocol data units are called, do not cross the boundaries of a local

network. Inter-network routing and global addressing are higher layer functions, allowing

data-link protocols to focus on local delivery, addressing, and media arbitration. In this way,

the data link layer is analogous to a neighborhood traffic copy; it endeavors to arbitrate

between parties contending for access to a medium, without concern for their ultimate

destination. When devices attempt to use a medium simultaneously, frame collisions occur.

Data-link protocols specify how devices detect and recover from such collisions, and may

provide mechanisms to reduce or prevent them.

Delivery of frames by layer 2 devices is effected through the use of unambiguous hardware

addresses. A frame's header contains source and destination addresses that indicate which

device originated the frame and which device is expected to receive and process it. In contrast

to the hierarchical and routable addresses of the network layer, layer-2 addresses are flat,

meaning that no part of the address can be used to identify the logical or physical group to

which the address belongs.

The data link thus provides data transfer across the physical link. That transfer can be reliable

or unreliable; many data-link protocols do not have acknowledgments of successfulframe

reception and acceptance, and some data-link protocols might not even have any form of

checksum to check for transmission errors. In those cases, higher-level protocols must

provideflow control,error checking, and acknowledgments and retransmission.

In some networks, such asIEEE 802 local area networks, the data link layer is described in

more detail withmedia access control (MAC) andlogical link control (LLC) sub layers; this

means that theIEEE 802.2 LLC protocol can be used with all of the IEEE 802 MAC layers,

such as Ethernet,token ring,IEEE 802.11,etc., as well as with some non-802 MAC layers

such asFDDI.Other data-link-layer protocols, such asHDLC,are specified to include both

sub layers, although some other protocols, such asCisco HDLC,use HDLC's low-level

framing as a MAC layer in combination with a different LLC layer. In theITU-TG.hn
http://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Network_segmenthttp://en.wikipedia.org/wiki/Transfer_%28computing%29http://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/ADCCPhttp://en.wikipedia.org/wiki/Frame_%28networking%29http://en.wikipedia.org/wiki/Protocol_data_unitshttp://en.wikipedia.org/wiki/Data_framehttp://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/IEEE_802http://en.wikipedia.org/wiki/Media_access_controlhttp://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/IEEE_802.2http://en.wikipedia.org/wiki/Token_ringhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/FDDIhttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/Cisco_HDLChttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/G.hnhttp://en.wikipedia.org/wiki/G.hnhttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/Cisco_HDLChttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/FDDIhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Token_ringhttp://en.wikipedia.org/wiki/IEEE_802.2http://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/Media_access_controlhttp://en.wikipedia.org/wiki/IEEE_802http://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/Data_framehttp://en.wikipedia.org/wiki/Protocol_data_unitshttp://en.wikipedia.org/wiki/Frame_%28networking%29http://en.wikipedia.org/wiki/ADCCPhttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Transfer_%28computing%29http://en.wikipedia.org/wiki/Network_segmenthttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Wide_area_network


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MODELS

Ronja Tetrapolis: Range of 1.4 km (0.87 mi), red visible light. Connect

with8P8Cconnector into anetwork cardor switch.

Ronja 10M Metropolis: Range of 1.4 km (0.87 mi), red visible light. Connects

toAttachment Unit Interface.

Ronja Inferno: Range of 1.25 km (0.78 mi), invisible infrared light.

Ronja Bench-press: A measurement device for developers for physical measurement of

lens/LED combination gain and calculation of range from that

Ronja Tetrapolis:

Ronja Tetrapolis is a device for optical communication with 10Mbps full duplex speed over

1.4km. The device terminates an optical path. To operate a complete link, two devices are

necessary.

Ronja Benchpress:

This is a Ronja model that is not a communication device, but a bench for measuring lens

properties. You insert a combination of LED and lens into the bench and measure exact

transmitter gain of the lens+LED combination in decibels. You can then use this value to

calculate precise range of the device. This is handy for evaluating new types of LEDs, new

types of lenses or if you have doubts if your lens is of adequate quality for the device (for

example due to greenish haze).

Ronja 10M Metropolis:

This is another variant of Ronja similar to Ronja Tetropolis, but varying in its technical

specifications.

Ronja Inferno:

Ronja Inferno is a device for optical communication with 10Mbps full duplex speed over

1.25 km using infraredlight. The device terminates an optical path. To operate a complete

link, two devices are necessary
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Technical specifications:

Ronja Inferno:

Gross data rate 10 Mbps

Transmission

modeFull duplex (half duplex also supported)

Nominal range1.25 km with 130mm RX loupe lenses and 90mm TX loupe lenses. The switch or cad has

to havewell implemented PLL.

Minimum

operating distance

1/4 of nominal range. Further manual reduction possible by change of two passive

components in receiver.

Data interface

Connects with RJ45 jack into IEEE 802.3 UTP interface. Must be plugged

directly into data terminal equipment (DTE, PC or a switch) using the integral

1m cable. Auto negotiation not supported, not transparent for auto negotiation

signals.

The preamble is chopped off more than specified by IEEE 802.3 which could

cause a problem when Ronja is connected into a cascade of pure hubs. However

hubs almost don't exist today anymore so it is not a problem.

Doesn't comply to IEEE 802.3 regarding not transmitting when link integrity is

not yet established. This violates page 303 14.2 g) - but IEEE 802.3 compliantdevices must work with it. Complying to it would make Ronja Tetrapolis more

complicated

Power

consumption

335mA @12VDC (4.02W) from wall cube, 2W from external heating power supply

(switchable off).

Typical Maximum

Idle 225mA 285mA

Full data load (both directions) 275mA 335mA

Operating

wavelengthInfrared, 875nm wavelength, 37nm spectral width

Optical output 30mW
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Ronja Tetrapolis:


Transmission

modeFull duplex (half duplex also supported)

Nominal range 1.4km with 130mm lenses. The switch or cad has to havewell implemented PLL.

Minimum

operating distance



Data interface

Connects with RJ45 jack into IEEE 802.3 UTP interface. Must be plugged directly

into data terminal equipment (DTE, PC or a switch) using the integral 1m cable.

Auto negotiation not supported, not transparent for auto negotiation signals.

The preamble is chopped off more than specified by IEEE 802.3 which could cause

a problem when Ronja is connected into a cascade of pure hubs. However hubs

almost don't exist today anymore so it is not a problem.

Doesn't comply with IEEE 802.3 regarding not transmitting when link integrity is

not yet established. This violates page 303 14.2 g) - but IEEE 802.3 compliant

devices must work with it. Complying to it would make Ronja Tetrapolis more

complicated

Power

consumption

285mA @12VDC (3.42W) from wall cube, 2W from external heating power supply

(switchable off).

Typical Maximum

Idle 185mA 245mA

Full data load (both directions) 225mA 285mA

Operating

wavelengthvisible, 625nm, 100nm spectral width (618nm perceived wavelength, red-orange)

Optical output 17.2mW

Divergence cone

half angle1.9mrad (130mm aperture transmitter lens)

Estimated Optical

EIRP

20kW (130mm aperture transmitter lens, HPWT-BD00-F4000)
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Operating

temperature-30...+70degC (outdoor part - optical heads, RX, TX), 0...+55degC (indoor part - Twister2)

Operating

humidity

Up to 100% (condensing) with lens heating on (outdoor part), up to 95% with lens heating

off (and indoor electronics).

Weight 15.5kg (one side of a link, on a welded parallel console)

Required visibility 4km at maximum range.

Optical

modulation

BPSK (as on AUI aka Manchester) plus 1MHz asynchronous 50% duty cycle square wave

between packets. The transmitter appears to shine permanently and steadily no matter if data

pass or not.

Indicators LEDs Power, Receive Packet, Transmit Packet

Aiming systemVisual, retro reflector for transmitter and DC voltage signal strength monitor port for

receiver.

Mechanical

Installation

Constraints

Possible mount places:

PlaceIs drilling

necessary?

Railing, round or rectangular No

Wall Yes

Corner of wall Yes

Chimney No

Horizontal or tilted surface of masonry or

masonry covered with tin, foil etc.Yes

Ceiling Yes

Max. 1m from RJ45 connector is a grounded metal box with dimensions

180x123x62 mm.

Cable distance between RJ45 connector and optical head mounting points is max.

100m


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Ronja Benchpress:

Operating ambient temperature 0+55C

Usage environment Indoor

Operating humidity 0-95% noncondensing

Ronja 10M Metropolis:


Transmissionmode

Full duplex only

Nominal range1.4km with HPWT-BD00-F4000 and 130mm lenses. The switch or cad has to havewell

implemented PLL.

Minimum

operating

distance



Data interface

IEEE 802.3 Attachment Unit Interface (AUI). Connector male DB-15 with screws instead of

AUI mechanical latch. AUI cable not supported - integrated cable length 1m. The preamble is

chopped off more than specified by IEEE 802.3 which could cause a problem when Ronja is

connected into a cascade of pure hubs. However hubs almost don't exist today anymore so it is

not a problem.

Power

consumption300mA @12VDC (3.6W) from AUI, 2W from external heating power supply (switchable off)

Operating

wavelengthvisible, 625nm, 100nm spectral width (618nm perceived wavelength, red-orange)

Optical output 17.2mW

Divergence

cone half angle1.9mrad (130mm aperture transmitter lens)

Estimated

Optical EIRP

20kW (130mm aperture transmitter lens, HPWT-BD00-F4000)
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Operating

temperature-30+70C (outdoor part - optical heads, RX, TX), 0+55C (indoor part - AUI interface)

Operating

humidity

Up to 100% (condensing) with lens heating on, up to 95% with lens heating off.

Weight 15.5kg (one side of a link, on a welded parallel console)

Required

visibility4km for uninterrupted operation at full range.

Optical

modulation

BPSK (as on AUI) plus 1MHz asynchronous 50% duty cycle square wave between packets.

The transmitter appears to shine permanently and steadily no matter if data pass or not.

Indicators LEDs Power, Receive Packet, Transmit Packet

CONCLUSION

The Twibright Ronja datalink thus, can network neighbouring houses with cross-street

ethernet access, solve the last mile problem for ISPs, or provide a link layer for fast

neighbourhood mesh networks.


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Our LED has a max response of 20ns (50 MHz). So we would run into a problem if we

wanted to increase the speed to 100Mbits/s by transmitting in a similar manner with the LED.

There are a few solutions. We could use a LASER which has much faster response rates than

LEDs and read in the MLT-3 and transmit NRZ at max frequency of 62.5 MHz, with the

receiver converting NRZ back to MLT-3. We can also communicate in parallel instead of

serial, we would require several transmitters and receivers. For example if we had three

transmitters/receivers then each transmitter could handle a maximum frequency of 21Mhz.

Using multiple transmitters/receivers brings up several issues: noise from other transmitters,

4B5B would not guarantee a hi-lo transition for each detector, mounting space issues. One

thing is certain making a 100Mbit/s network would be easy.

PROS AND CONS

Pros:


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1) The parts were chosen to be of the widest availability possible and equivalents are

provided where applicable.

2)

Innovative approach is used to speed up the work and make it convenient. Sector

codes are present to make the population easy. Drilling is simplified by drilling

templates - just print and no measurement is necessary in the workshop!

3)

Withstands -20C as well as direct sunlight and heat with obvious margin. During a

lightning storm, lightning strike in proximity usually doesn't generate even a single

lost bit.

4) In case of device failure (direct lightning strike), the measuring points can be

inspected and bad components replaced without a need to throw the whole device out.

Cons:

1) Ronja is somewhat labor expensive. Things have been made much easier by putting

the most complicated electronics on a PCB. The cost of parts is negligible in

comparison with the labor, for example the components for the whole Ronja 10M

Metropolis cost just 1500CZK. Further reduction in labor demands is planned by

putting RX and TX on PCB too.

2)

The user must possess certain basic manual skills as soldering, drilling, painting, and

technical drawing/schematic reading. But people without any previous experience

with soldering have built a piece that worked on the first try!

3)

The user must not cut the corners during the building.

REFERENCES


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Twibright Labs. Ronja. .

Kenneth Krane. Modern Physics Second Edition. John Wiley &

Sons, Inc.

www.wikipedia.org

Twibright Labs. Making Ronja on short tracks.

.
http://www.wikipedia.org/http://www.wikipedia.org/http://www.wikipedia.org/

Documents

Ronja(Reasonable Optical Near Joint Access) Report