Views / News – Blog

Operational Technology (OT) vs Information Technology (IT)

OT and IT: What’s the Difference?

Information Technology (IT)

Information Technology (IT) is a familiar concept to most modern office workplaces encompassing the products and networks providing data-centric computing, supporting various business functions such as finance, personnel, management and administration. This has grown to being fundamental to corporations large and small, and continues to rapidly develop in scale and capability.

Operational Technology (OT)

By contrast, Operational Technology (OT) is understood by utilities, transport, manufacturing and other industrial sectors, as encompassing an array of systems engineering, event monitoring and process control to facilitate operations. Historically, the technologies and products used to implement the required infrastructure have been bespoke and separate from other corporate systems.

The growth of standardisation

With the explosion of computing devices, the internet and communications generally, the underlying IT hardware and software have become ubiquitous and standardised. The majority of businesses now deploy products and networks which are interchangeable with most other global corporations, bringing overall costs down, increasing ease-of-use and enabling global inter-operations.

In recent years, there has been a trend to capitalise on these developments by seeking to replace old OT bespoke systems with widely available and deployed IT products.   

The problem with convergence

Despite the advantages brought by a move to using IT technologies to fulfil Operational infrastructure needs, there are some draw-backs. 

Although no-one wants systems to fail, and high performance is often a key requirement, in traditional OT systems, there is an emphasis on availability, reliability and ‘mission-critical’ operations, dictating deterministic technologies which standard IT products are not designed to provide. The packet-oriented ‘best-efforts’ nature of TCP/IP networking solutions is not sufficient to provide the performance required. Some operational systems have specific timing requirements, utilising PDH and SDH TDM-based technologies to deliver signalling and tele-protection information. 

For years, ‘security’ against ‘remote attacks’ was not an issue, because most OT systems were regionally based and not connected to the wider world. And even those with remote monitoring and control tended to use bespoke equipment which was not widely understood or utilised by non-specialists. With a move to going ‘on-line’, and utilising ‘standard’ IT equipment to fulfil OT requirements, this is no longer necessarily the case. Which brings the possibility of outages due to system or denial of service attacks. ‘Cyber-security’ in recent years has needed to become part of the considerations for OT infrastructure, learning from the experiences of threats to IT systems and ‘denial-of-service’ attacks. 

And whilst modern IT communications bring gigabit data bandwidths, OT data needs have remained modest, often to fulfil the unchanged monitoring requirements for an enormous existing deployed network of slow-speed kilobit data devices, such as pumps, valves and actuators. 

In short, the needs and desires of businesses for computing devices, networking systems and global communications to provide ever-increasing bandwidth and application support continues to diverge from the requirements of industrial operations, requiring availability, compatibility and mission-critical performance.  

Future trends

Whilst vendors of networks, computing and communications continue to develop advanced technologies to meet the growing needs of IT for businesses, the desired ‘convergence’ to replace OT systems continues to be a work-in-progress.

OT systems tend to be built with longevity as a priority over cost of ownership, due to the challenges of replacement once in continuous operation. Whereas IT products are often ‘written down’ and replaced over a much shorter timescale, with a view to taking advantage of continuous developments to provide higher performance and productivity.

Consequently, technologies that are considered ‘legacy’ by IT professionals continue to be maintained and even further deployed as trusted and proven OT systems to fulfil operational needs. 

Your operational systems requirements

@YellowsBestLtd would like to know your infrastructure goals, deployment experiences and maintenance challenges and how we may assist you to fulfil your OT and IT requirements, for both new and existing operational systems. We look forward to understanding your needs for technical support, solutions sourcing, repair services and equipment spares.

Optical Teleprotection Signalling (TPSO) Equipment (C37.94)

Electrical power systems protection

Teleprotection for power systems protection has been deployed by utility companies for many years. It’s purpose is to monitor the condition of the Electricity Grid, isolate faults, disconnecting faulty parts from the rest of the network and thereby prevent damage to critical parts of the power infrastructure.

Teleprotection is a physical interface between the telecommunications equipment and the electrical grid protection relays. When a fault occurs, the protection system switches on circuit breakers or reclosers to avoid a fault rippling through the network. Also, in the event of an outage, teleprotection helps restart power to a part of the grid.

Early teleprotection systems used voice-frequency signalling technologies. These were replaced by digital electrical Tele-Protection Signalling (TPS) equipment using 4 or 8 command channels encoded into a 64kbit/s standard digital data channel, in accordance with the ITU-T G.703 recommendations. This brought dependability and interoperability of systems, meaning that dedicated channels were no longer required as any standard digital transmission network could be used, separate from the power system.

This was later enhanced by the development of Tele-Protection Systems with Optical (TPSO) interfaces, which allowed the direct fibre connection between the teleprotection device and the primary multiplexer. 

The IEEE C37.94 standard for TPSO interfaces

The IEEE C37.94 standard defines an optical fibre interface for use between teleprotection systems and digital multiplexer equipment, operating at a data rate of nx64kbit/s. 

This allows the interconnection of different vendors teleprotection equipment with different vendors multiplexer equipment, without any restriction on the content of the nx64kbps data, using up to 2km of 50μm or 62.5μm multimode (or up to 20 km of 9μm single-mode) optical fibre.

Critical Systems deployment 

Teleprotection systems are typically installed in high-voltage transmission grids where distances are usually greater than in distribution grids and play a critical role in preventing instability in the grid and damage to expensive substation equipment.

Teleprotection systems monitor conditions on transmission lines and coordinate tripping of the transmission lines to quickly isolate faults. 

A teleprotection system usually has two components: a protection relay, which executes the actual switching; and the teleprotection equipment itself, which is the interface to the mission-critical communications network. 

Typical Teleprotection Systems Network

To ensure that the power systems are properly protected, real-time exchange of status information messages and commands between teleprotection equipment must be reliably transferred with tightly-controlled latency over a deterministic mission-critical communications network, traditionally composed of TDM multiplexers and optical PDH or SDH equipment. 

Nokia ‘Dynanet’ TPSO 24204

An example of a vendor’s multiplexer is the Nokia ‘Dynanet’ equipment family. This utilises the TPSO 24204 interface unit for connecting the teleprotection devices directly to the primary multiplexer. This provides four IEEE C37.94 standard interfaces, with nx64kbit/s optical data channels (where n is 1 to 12).

TPSO – 24204

Because of the direct connection, there is no need for a separate converter to change the optical connection to electrical. This eliminates electrical interference and data corruption caused by disturbances from the high voltage power line.

Your operational systems requirements

Let us know how we can assist you to keep your new and legacy systems operational with technical support, repair services and equipment spares. We look forward to hearing from you.

New and Legacy communication issues

Challenges with maintaining Legacy systems

It can make perfect sense to continue to run existing reliable and proven systems, especially if operational requirements have not changed. Alas, the developing nature of technology means that from time-to-time, issues arise. 

Changes to email encyption protocols 

Modern computer communication services support the Transport Layer Security (TLS) encryption protocol. This aims to protect the information sent and received over a standard Simple Mail Transfer Protocol (SMTP) connection between two computers while ensuring that they both agree and understand the method of data transfer.   

However, the earlier versions of TLS 1.0 and 1.1 have been deemed by the industry to be not secure enough and have been superseded by versions 1.2 and 1.3. You and/or your service provider may have already transitioned to the latest protocols. However, if you have old hardware running legacy software, as support from service providers is withdrawn, you may find your email stops working.

How you can tell if it’s an issue

If you’re using an Apple Mac then the Safari Browser has supported TLS 1.2 for web traffic protection since version 7 in 2013. However, if you’re still running ‘El Capitan’ OSX 10.11 with Apple Mail 9.3, it won’t support TLS 1.2 for email. Other computer hardware and software combinations may also run into problems.

Most browsers including Safari ended support for TLS 1.0 and 1.1 in March 2020, and various service providers have either already dropped or soon will withdraw operation of the older TLS protocols.

For instance, one.com will stop support of TLS 1.0 and 1.1 on 17th August 2021. Other service providers may have different end of life dates. If you’re using the one.com service then there’s an easy way to check:

send an email to:

protocol@tls-check.one.com.

This will provide an automated reply telling you what protocol you’re using (works with iPhones and iPads too), like this:

{
            “started”: true,
            “protocol”: “TLSv1.2”,
            “cipher”: “ECDHE-RSA-AES256-GCM-SHA384”,
            “keysize”: 256
}

Other service providers may have similar methods of verifying the protocols, so it’s worth checking with them. Failing that, you may be able to examine the headers of your emails, to look for something like this:

version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128

Solutions if you’re affected

To ensuring your email continues to function, the options include: 

  1. Updating your operating system. In the case of Apple Mail on Mac computers, this means moving to ‘Sierra’ OSX 10.12 as Mail cannot be separately upgraded.
  2. Using a different email client with TLS 1.2 support, e.g. Mozilla Thunderbird.
  3. Using a browser based solution for your email
  4. Changing your settings to send and receive email without encryption (not recommended) 

Balancing New Requirements and Legacy Support

If you want to stick with your current hardware and software choices, this does present a problem, particularly if you’re otherwise happy with your setup and are unable to upgrade.

Alas if you want full compatibility (and security) with the latest industry supported functionality, whilst retaining operation of other  legacy applications, consideration has to be made to invest in new hardware to run in parallel with older systems, which continue to be maintained to perform dedicated compatibility functions.

YellowsBest: Keeping Customers Operational

If you have similar or other new requirements and legacy maintenance needs, please get in touch to discuss how we may be of assistance to keep you operational.

Challenging times demand time for a change!

New “UK” launch

It’s been a challenging time for businesses generally, and particularly in the United Kingdom, with Brexit in many cases adding cost and time to trading, and Covid-19 restricting travel and networking.

So it seemed an appropriate time to launch a new varient of the Yellows Best Limited website, now additionally utilising “.co.uk” as a signifier of commitment to our home market location.  

Keeping Customers Operational

The new YellowsBest.co.uk promotes the same blend of Services and Solutions for “Keeping Customers Operational”, but presented in a different and modern single-page layout, making it particularly mobile device-friendly where ‘vertical scrolling’ is more appealing than using the traditional ‘horizontal tabbed’ layout.

We hope this provides Customers old and new with a welcome alternative, though the original YellowsBest.com will continue to be maintained, along with it’s associated blog for ‘informal’ views and news updates.

Assisting with your requirements

It would be interesting to receive feedback as to how useful you may find this additional site, and whether there is anything else you’d like to see featured.

Of course, @YellowsBestLtd online content ultimately serves the purpose of highlighting the types of services and solutions we can provide. Customers may therefore be prompted to get in touch to discuss their specific requirements, which we can usually assist with.

Rest assured, if you use either contact address:

enquiries@yellowsbest.co.uk

enquiries@yellowsbest.com

we’ll receive your message and will be in touch by return. We look forward to hearing from you! 

eTrike Conversion Project

More fun going electric

With the combination of moving to a more sustainable future along with a fitness drive encouraging people to be more active, one thing growing in popularity is the “eBike”, which supplements the efforts of the rider with a low speed assistance from an electric motor.

eBike

This means you don’t need to be young or super-fit to enjoy getting out and about, with good speeds and longer distances very achievable. And if you want a challenge, you can always switch the assistance off!

Ebikes come ready built to ride away, but an existing machine can be converted.

The three-wheeler challenge 

Given the benefits to two-wheeled cycling from going electric, a similar upgrade to an existing 3-wheeled recumbent trike was called for.

eTrikeOriginal
eTrike awaiting conversion

In principle, this is ‘simply’ a matter of adding an electric motor and a battery, which is indeed what was done, but there were a few challenges along the way.

Step 1: choosing the electric motor location

The first major decision to make when converting or purchasing any electric cycle is the location of the motor; there are three options: front-wheel, rear-wheel or bottom-bracket mount. For the Trike, with its two small forward wheels, front mounting is not possible. The rear option would require the replacement of the wheel with one with a hub motor, and anyway this can be considered an inferior location given that the motor drive is separate from the rider’s push of the pedals. 

Consequently, a bottom-bracket motor was selected, which confusingly on a recumbent trike is not a ‘centre mount’ because it is located at the front, ahead of the front wheel.

Step 2: Motor selection

There are now an expanding number of manufacturers of electric cycle motors, but some of these are only built into new bicycles, and others are prohibitively expensive kits. However, some very affordable Chinese products are available via AliExpress. The selection of the Tongsheng 36V 250W Tsdz2 model from pswpower was made.

TSDZ2
Tongsheng Tsdz2

Given the restriction in the UK of a maximum speed of 15.5 mph for powered assistance and limit of 250W, this unit is perfectly adequate for the intended task.

Step 3: Bottom Bracket ‘special’ fit

The ‘Bottom Bracket’ is the place on all cycles which enables the pedals to rotate, with bearings facilitating the movements of cranks. However, there are many ‘standards’ of different manufacturers models, so getting a motor to fit in place is not necessarily straight-forward. The existing Trike had what is known as an Ashtabula or ‘American’ one-piece crank’ (OPC) Bottom Bracket, whereby the cranks for the pedals on each side are formed from a single unit and uses a 51.3mm bearing cup pressed into the frame.

OnePeiceCrank
American style one-piece-crank


CrankRemoval
Removal of the cranks

Unscrewing the crank retaining nut was aided by use of a Park Tool HCW-18 spanner. One of the pedals was taken off, the bearings teased out, and the crank fed out. Then a brass drift punch bar helped to hammer out the mounting cups from each side.

The difficultly then came that the mounting shaft of the Tsdz2 motor is smaller than the bottom bracket diameter, and is also offset. Fortunately, there is a perfect conversion solution to this problem already available, called the Eccentric BB adapter. This converts the Ashtabula empty shell to standard BSA size 34mm diameter (68mm width), but also is asymmetrical mounting which perfectly accommodates the offset motor shaft. This though is somewhat tricky to source; eventually located at Luna Cycle in CA, USA.

eccentricBBadapter
Eccentric BB American to BSA adapter

Fitting the adapter required careful insertion either side, being a close fit and needing gentle assistance with a mallet, also ensuring that the rotation of two halves lined up.

BBadapter
Eccentric Adapter in place

But once fitted, the motor was slid in and the offset mounting ensured that the shaft located without difficulty or fouling of the frame. The retaining bracket was fitted to the motor and secured with two M5x16 bolts, and then the M33 retaining nut was screwed into place and tightened using the special ring spanner tool supplied with the motor.

MotorInPlace
Securing the Motor

The fixing block was then attached with an M8x40 bolt, and the motor assembly secured in place using the bridge-plate, needed to prevent the possibility of the motor rotating in the crank when being powered in operation.

Step 3: Cranks and pedals

The cranks then fitted to the motor spindles either side. The supplied 170mm long parts were too long for the recumbent machine, being designed for a standard bicycle, and hence a pair of 152mm cranks were sourced, which matched the length of the original ones, which being an all-in-one unit couldn’t be reused. Neither could the pedals, which were a different screw size, and so standard gauge replacements were fitted.

CrankFitment
Fitting the Cranks

These feature a reverse thread for the left-hand side, which therefore was secured by anti-clockwise rotation, whilst the right hand naturally secures clockwise. 

Step 4: Battery fitment

Next came the addition of the 36V 13Ah Lithium-Ion power source. There are various types that can be used on standard bicycles, including down-tube or top-tube units, and bottle-type, but the recumbent trike doesn’t have space for any of these. Instead, it was necessary to add a rear carrier, mounting over the rear wheel, to house a rack mounting battery purchased through eBay from 167-tradeworld-uk. This wasn’t a completely straight-forward fit, as first the rear axle position had to be slightly centralised to accommodate the brackets, and then 16mm pipe clips were needed be added to the frame behind the seat for attaching the front stays to secure the rack. This ensured that the rack didn’t slide or rotate forwards or backwards in use with the weight of the battery.

Rear Rack and Battery

With the rack secured, the purpose-built battery housing was screwed in place on the lower row of the carrier. Then the battery was slid into place and secured with its key lock. Charging of the battery can be made in situ, though it can also be removed for this purpose. This was fully charged using the dedicated mains / 36V power supply adapter.

Step 5: Display mounting

An important part of the electric conversion system is the incorporation of a display, which connects the power and controls the cycling assistance, whilst also providing useful data such as speed, distance and charge remaining.

VLCD5 Display

For this project, a VLCD5 display was chosen, ideal for the purpose. Due the limited room and mounting options, given that there are no high up handlebars or top tube on the recumbent trike, the display was mounted centrally on the low steering crossbar. This was secured via the two horizontal attachment loops, thus in use being positioned between the rider’s legs.

Optional remote button control

The optional remote button control was additionally located on the left handle grip, though this was subsequently found to be of no practical use in operation.  

Step 6: Wiring up

With all the main components in place, all that was left was to make the various wiring connections, starting with linking the battery to the motor. The battery came with an XT-60 socket, whereas the motor has 4mm bullet connectors. Also, due to the forward mounting location of the motor, a cable of approximately 1m was needed to link the parts, converting the connection types in the process. 

Next, the speed sensor was fitted to the left-hand rear wheel stay and accompanying magnet to the spokes, by means of cable ties. This is the means by which the control unit calculates and therefore displays the speed and distance travelled.

Speed Sensor and Wheel Magnet

The attached cable contains a splitter which is used to connect to both the display unit and also optional front and rear lights. Chosen for this purpose was an AXA Echo 15 switch for the front, and a Lynx rack mounting e-bike red LED for the rear, both of which fortunately accepted the 2.8mm mini spade connectors on the wiring harness.

Front and Rear lights

This combination cable was again too short to link the display with the sensor, so an additional 1m speed sensor extension N58B cable was added, this having the required 6-pin male/female connectors to plug into the splitter cable and the corresponding motor connection.

Step 7: Powering up and Configuring

The final step was to switch on the battery using the key and control panel with a press of the power button, and then set about configuring the system parameters.

Display switched on

The wheel size was set to 20 inches, and the distance measurement to miles. The i-button on the display module cycles the modes from ODO (total distance), TRIP, AVG (speed) and TIME. The +/- buttons increase/decrease the selected assistance level from ECO (minimum), TOUR, SPEED to TURBO (maximum).

The front and rear lights can be switched on and off with a short press of the power button. The rear battery light can be additionally manually switched on.

A long press of the power button switches the display off.

Finishing up and testing 

To finalise the build, some cable sheaths were added to tidy up the wiring, and cable ties secured all the leads. The original flag (useful for visibility for such a low-down vehicle) was cable tied in position against the rear rack.

eTrike complete with Flag

The eTrike frame was adjusted for the right seating position. Now was time for a test ride! 

Completed eTrike project

The completed machine performed perfectly well, providing, as most electric cycles do, assistance from a stationary start up to the legal maximum of 15.5 mph. Pedalling effort is still required by the rider, but the effect is to ‘flatten’ hills (and reducing the need for gear changes), making the experience less strenuous and more enjoyable, maintaining a greater average speed and achieving longer ride distances.  

In conclusion, the eTrike conversion was relatively straight-forward, once all the necessary component parts had been identified and sourced. Since recumbent trikes are a somewhat specialised form of cycle, and tend not to be alike, then it is to be expected that a degree of customisation is required to achieve the build of a suitable electric conversion.  

Your transformation projects

@YellowsBestLtd assists customers in developing their business and improving and maintaining their infrastructure. Should you have any requirements or plans, please get in touch to discuss how we may be of assistance. 

Mobile Evolution and the Extinction Event

When Giants ruled … mobile communications

A long time ago, great “Dinosaur beasts” of Mobile Communications were supreme.  The beginnings were in the 1970’s with the launch of a Motorola handset weighing 2kg. This was followed by other barely portable products with huge batteries such as the Nokia Talkman. Only for the ‘new adopters’ who had to be in touch all the time.

Then came the ‘Bricks’ 

From these humble beginnings, soon a range of solid, reliable but ‘bricklike’ big and heavy phones appeared, like the Nokia 2110 and the Motorola Dynatac 8000X, as featured in the 1987 movie “Wall Street”. Designed for upwardly mobile business people.

Diverse expansion 

Then came a period of rapid expansion with a diverse range of more affordable products to suit wide consumer tastes. Various forms, colours and accessories became more and more important, with slide phones like the Nokia 8110 as featured in the 1999 film “The Matrix” and flip phones like the Motorola Razr, providing a ‘Star Trek’ appeal.

Feature explosion

An expansion of more and more features to make mobiles do more fuelled the explosion of product ranges. Cameras and music players were added to increase the functionality of these increasingly sophisticated and compact pocket-sized devices, such as the Nokia 6230.

6230
Nokia 6230

A glance at the 2004 Carphone Warehouse catalogue shows how varied mobiles had become, with the top 10 dominated by Nokia, Sony-Ericsson, Siemens and Motorola as the biggest manufacturers of the time.

2004 Carphone Warehouse “Top 10”

‘Tyrannosaurus’ functionality heavyweights 

For a while, the king of the land was the bulky, terrifyingly expensive but impressive (for its time) Nokia Communicator, offering phone, text, email and even fax. Opening up to reveal a full QWERTY keyboard, the range started with the 9000 which appeared in the 1997 film “The Saint” and had evolved by 2007 into the even more powerful E90.  

LegacySmartPhone
Nokia E90 Communicator

Extinction Event: The Death of the incumbents

But then came biggest shock to the world of mobile communications: the launch of the first Apple iPhone on 9th January 2007.

Like a meteorite striking the earth, this shock spelt the end for many mobile types which couldn’t compete with the sudden demand for ‘touch-screen’ devices using apps.

Indeed companies like Nokia, once the biggest of them all, couldn’t adapt and died a death, as well documented in the BBC documentary “The Rise and Fall of Nokia

Survival of the fittest

The ‘smartphones’ from Apple and later Android-based from the likes of Samsung became an increasing hit, wiping out much diversity and seeing a seismic shift away from many form factors to the now standard “slate” style of device.

Apple iPhone 4
Apple iPhone 4

Some ‘featurephones’ as they came to be known have lingered on, and in recent years companies like HMD global, who under licence have taken some iconic Nokia designs such as the 3310 and made a successful relaunch. Diversity is now finally creeping back with new variants such as the ‘folding’ Samsung Galaxy Z Fold2.

Your Paradigm shifts

Any memories or stories to tell? @YellowsBestLtd would be keen to hear your thoughts and experiences of sudden technology ‘paradigm shifts’. Let us know if we can be of any assistance with your future solution or services requirements. 

Legacy Transmission & Line Codes

Before Fibre, there was copper!       

It’s almost difficult to believe that not so very long ago (ok, going back maybe more than 50 years) there were no optical fibre or digital transmission paths of any flavour of technology providing our communications infrastructure.

Analogue FDM

From early to mid 20th Century, an extensive core copper cable network was rolled out, based on analogue FDM (frequency Division Multiplexing) over coaxial pairs, with the valve-based technologies occupying a lot of space and consuming much power. 

Digital PCM

The late 1960s saw the introduction of digital PCM (Pulse Code Modulation) sampling at 8kHz. The ITU-T (International Telecommunication Union – then known as CCITT) standardised 30-channels at 64kbit/s in a 2.048Mbit/s multiplexing system, using 8-bit A-law algorithm (the USA adopted 24-channel 1.544Mbit/s with μ-law algorithm).

Problems with high bit-rates

The higher bit rates gave rise to crosstalk interference problems on many existing cables. Also, data signals transmitted as voltage levels in unipolar NRZ (Non-Return to Zero) format are not self clocking and have a significant DC component, wasting power. Bipolar RZ (Return-to-Zero) type AMI (Alternate Mark Inversion) coding prevents the build up of the DC-component for longer distance and addresses the issue of data containing multiple ones. However, long sequences of zeros still present problems with a lack of transitions causing difficulties maintaining synchronisation.

Introduction of Line Codes

Line Coding of the format mB-nB was introduced to overcome these issues. Initially 4B3T (four Binary, three Ternary) was used. This encodes each 4-bit input group into a 3 symbol output using the three states of positive, negative and no pulses.

e.g. ‘0000’ is coded as ‘+0-‘

This improved efficiency in terms of bit per symbol over AMI, which itself is an example of a 1B1T code. Improvements in transverse screened cables were also made. However, transmission problems with high-speed digital data were still encountered due to unsuitable copper cabling which needed to be addressed.

PDH Higher Order Multiplexing

By the late 1970s, the UK had adopted the ITU-T recommended PDH (Plesiochronous Digital Hierarchy) of E-carrier higher-order multiplexing at 8Mbit/s, 34Mbit/s (in the US, T-carrier at 6Mbit/s, 45Mbit/s) and 140Mbit/s. 

The lower rates of the E-carrier system adopted HDB3 coding, which replaces 4 ‘0’s with ‘000V’ or ‘B00V’ (or in the US for T1, B8ZS coding which replaces 8 ‘0’s with ‘000VB0VB’).

CMI (Coded Mark Inversion) was included in the ITU-T standards for higher-order PDH at 140Mbit/s PCM (as well as SDH at 155Mbit/s electrical STM-1). This is a 1B2B type of NRZ coding where a ‘0’ is represented by ’01’ and a ‘1’ as an alternatively ’00’ and ’11’, with +V and -V representing the coding levels.  

The advantage of the coding is it makes clock recovery by the receiver simple and for maintaining synchronisation alignment with a long sequence of ‘0’s or ‘1’s.     

Line Coding examples

Optical fibre systems

From the beginning of the 1980s, early optical-fibre multi-mode systems operating at 850nm were deployed, and later single mode at 1300nm, using the PDH multiplexing capacities. 

Typical of long-haul PDH optical-fibre systems, the 2 Mbit/s, 8 Mbit/s and 34 Mbit/s ‘Dynanet’ products from Nokia have ITU-T G.703 compliant digital interfaces using the HDB3 code, but using an optical transmission Line Code of 5B6B. This is another type of mB-nB code, where in this case 5 bit data words are coded using 6-digit code words

e.g. ‘00000’ being represented as ‘100111’. 

As well as its use on electrical systems, CMI Line Coding has also been popular for use on short-haul optical-fibre transmission such as ’tactical’ fibre optical systems operating at 2 Mbit/s.

SDH / SONET – A different approach

For optical SDH systems, STM-1 and above, scrambling is employed instead of line codes to ensure the incoming bit stream contains sufficient transitions for maintaining synchronisation. This works by combining the data signal with a pseudo-random bit sequence generated by a scrambler polynomial generator.

i.e. with a sequence of length of 127, the generating polynomial is 1+x6+x, leading to input data ‘00000000001111111111’ being scrambled as ‘11111110000001000001’.

Optical PDH still serving

In most cases higher-order optical PDH has been decommissioned, but optical transmission at 2Mbit/s is still in operation for many low-data rate applications, where costly replacement with SDH, WDM or carrier Ethernet would bring no advantage. An example product is the Nokia DF2-8 which continues to offer reliable access services, particularly in the Utilities and Transportation industries.

DF2-8 – TA 21518

Copper systems still in operation 

Though core copper electrical transmission systems have now been discontinued, much of ‘last mile’ telephony and related broadband connections are still copper access. For extended data transmission applications, copper systems are still deployed and maintained. Such products include the Nokia DSL2i copper line equipment (including power feeding repeaters) using SHDSL (Single-pair High-speed Digital Subscriber Line). This uses TC-PAM (Trellis-Coded Pulse-Amplitude Modulation) which is a 4B1H Line Coding, since translates 4 binary digits into 1 Hexadecimal (16) levels. It improves range, especially when used with regenerative repeaters, and improved ADSL (Asymmetric Digital Subscriber Line) compatibility. 

ACL2i PF GEN – T65580

Feedback and assistance

This has been a necessarily very brief run-through of legacy transmission and some of the Line Codes employed. @YellowsBestLtd would be keen to hear your experiences and knowledge of transmission systems and performance of Line Codes. If we can be of any assistance with your solution requirements, including both new and legacy technologies, then please get in touch

Lessons from the ‘Lockdowns’ for Business

Seeking the ‘new normal’

Most workplaces have seen some considerable disruption over the last year due to the restrictions necessary to deal with the global Covid-19 virus pandemic. Hopefully things are going to get easier over the coming months. But before we race to ‘get back to normal’ (if that’s indeed possible), let’s consider some unexpected benefits we might want to hang onto.

Work is what you do, not where you do it

Commuting has always been a drag. The time wasted driving, not to mention the cost, in order to reach an office in which documents are written, emails are read and replied to, and phones calls are made. Or instead, various ‘productivity’ applications are used. All of which could be done from home. What is needed is a ‘mind-shift’ to recognise that “I’m off to work” can mean engaging in an activity rather than physically travelling somewhere. 

What’s the point of an office?

The broad acceptance that an office is where ‘work happens’ is due to the familiarly of their existence over a number of years. Once upon a time there were good reasons why work had to be so: people needed the facilities they provided, including main-frame computers, desk telephones, fax machines, printers, typing-pools (yes, really – people once didn’t type their own documents!) And memos – remember those ‘internal mail’ envelopes? But now, with laptops and mobile phones and broadband internet, it’s no longer critical to all share the same space.

People ‘like’ keeping in touch

The reality of the office is that it’s no longer a critically functional resource hub, but there are some social benefits over working remotely. It’s a place to meet and greet, share ideas and stories, help each other and generally contribute to high morale. People enjoy discussing last night’s TV or the football. Lasting bonds and relationships are formed, sometimes even being introduced to future partners. Not sure all employers would see this to be their ‘role’; the social side can of course be achieved in other ways. Anyway, flexible remote working offers the opportunity for better work-life balance.

Meanwhile, bosses like collecting their workers in one place as then it’s easier to ‘manage by walking about’. There’s a trust element: how can the staff be really hard at work if they’re not visible, aka ‘chained to the desk’. But following McGregors’s ‘Theory X (authoritarian) and Theory Y’ (participative) style of management, you either micromanage them because they’re not motivated, or trust people to take pride in their work and get the job done. So forcing people into an office isn’t the answer to productivity. Rather, pick the right people, train and support them, give them ownership of their tasks. Let them work where and when they need to. Use performance reviews as a tool (not a chore) to keep on track and set rewarding goals.   

Quantity or Quality

The crazy thing about the 9-5 office culture is people vary between not having enough time to get a job done, and piloting a desk ‘looking busy’, because they’re supposed to be ‘in’. Flexible working on the other hand recognises that people have lives with things that need scheduling from time to time, around varying business demands and commitments. Allowing people the discretion to manage their work-life balance means better motivated and focussed staff who will put the extra effort in when needed. Or else, managers need to take strong decisions on appropriate resources and team composition. Working ‘smarter not harder’ certainly doesn’t mean forcing everyone into an office and making them work all hours.

Meetings expand to fill the time available

It seems like ‘work’ to spend hours in meetings showing each other an endless supply of presentation slides. Discussions often arise involving only a few participants while others wait passively. The reality is very little is accomplished that couldn’t have been better reviewed remotely, in one-to-one conversations or communicated more broadly via team or company-wide bulletins.

Keep your germs to yourself!

Due to the emphasis on ‘attendance’ (perhaps ingrained in people from their school years), there’s often a culture of ‘bravely struggling in’ when ill with a cold, thus almost guaranteeing the sharing amongst all colleagues. Above all else, the pandemic has shown the sense in keeping people separated to reduce the spread of illness. 

Better for you, better for the environment

Not everyone can work from home, and certain tasks can’t be done remotely. But it’s time for a re-evaluation of what journeys are ‘necessary’ and what are the most productive work patterns, both in terms of getting the job done (without sitting in traffic jams for hours) and maintaining a flexible, motivated workforce. Not least because of the unsustainable effect on our planet’s finite resources and impact of climate change due to limitless business activities and excessive travel.

Are you ready for the ‘paradigm shift’?

@YellowsBestLtd we’d be interested to hear your thoughts and feelings about the changes brought about by Covid-19, and how you see habits changing for the future. Will you be rushing back to the office, or reaping new flexibility from remote working? Please get in touch, and let us know how we can help with your continuing business requirements. We look forward to hearing from you.

International Trading (Post Brexit)

New rules for Business

It’s been an uncertain period leading up to the United Kingdom (UK) leaving the European Union (EU). Now that that ‘Brexit’ has happened, as of 1st January 2021, businesses are having to work out the practical changes having an impact on international trading.

The reality of the situation is that it will take time to fully understand the new rules and what effect they have on imports and exports. Due to this uncertainty, some companies are choosing to curtail international activities, which is having an effect on availability of supply.

So this is a subject that will need to be revisited as experience is gained. What seems likely is that there will be more administration and higher costs.

@YellowsBestLtd has a 5-year history of trading not just within the EU, but globally, and it’s this experience which is helpful in understanding the adjustments needed. Put simply, all import and export business within and beyond the EU is now ‘similar’ in principle in terms of customs and tax, with or without government ‘trade deals’ being agreed.

VAT charging and reclaim in the UK

It’s helpful to first understand how VAT works on a national level. In the UK, it’s charged on the sale of many goods where ‘value has been added’ at a rate of 20% of the selling price. To consumers, that’s just a tax they pay within the total purchase price. For businesses, that element of the sale is ‘collected’ on behalf of the government, totaled and paid quarterly via their tax return. However, VAT-registered businesses are able to ‘claim back’ the taxed paid on their own purchases. The logic being, that when you’re ‘trading’ i.e. buying and selling, the amount of tax due on goods is that relating to the ‘value add’ – so the difference between the tax charged on the cost price and that charged on the selling price. Which of course should be more, if you’re making any kind of profit.     

How VAT previously applied for UK businesses trading within the EU

To avoid the complications of how to ‘settle’ the collection and claiming back of taxes on purchases made between EU member states, an arrangement is in place such that each country is responsible for  their own VAT affairs.  Here’s how charging for VAT works for businesses when trading within the EU:

  1. The goods are zero-rated for VAT, from suppliers that are VAT-registered. This means that the export invoice, stating “intra-community supply”, charges VAT at 0%.
  2. The VAT-registered buyer (importing company) then declares the ‘acquisition’ on their VAT return (in “Box 2”)
  3. The buyer simultaneously also ‘reclaims’ the VAT (included in “Box 4”) on the same VAT return
  4. The logic behind these transactions is that the purchaser acts as both the “seller and the buyer”, for VAT purposes, Hence the transaction is accounted for entirely within one member state, and no funds need to be transferred to or from the tax authorities.  

When these arrangements applied to UK businesses selling goods to buyers in EU member states, a ‘VAT EC Sales List” also needed to be completed and sent to the HMRC.      

VAT and trading globally

Now the UK is ‘outside’ the EU, the ‘intra-community’ arrangement for VAT no longer applies from 1st January 2021. Instead, all international trading follows the same process, for all countries both within and beyond the EU.

UK businesses making global purchases receive an invoice from their international supplier which has no VAT added. But the UK government will separately charge VAT at 20%; this amount needs sending directly to HMRC. Typically, this amount will be collected by the courier physically transporting the goods, and normally an administration fee will be additionally charged for this transaction. If an agreement hasn’t been made with the seller, it is often the case the buyers find they need to pay these additional costs before the imported goods will be released from customs and delivered. Reclaiming of import VAT will then be made via the VAT return as an input tax, following the normal rules for UK-paid VAT. 

Alternatively, import VAT can be accounted for using “postponed VAT accounting” on the VAT-return, which essentially is a similar scheme to the EU “intra-community” arrangement. This requires ensuring that the courier is advised how import VAT will be accounted, so they can complete the customs declaration appropriately.

Similarly, UK businesses selling goods internationally don’t add VAT to their invoices, but are likely to have import taxes added by the authorities in the receiving country. If the buyer has not agreed to include these additional costs within their purchase order, this can mean that the seller needs to settle these charges as part of their cost of supply, typically being charged by the courier used to deliver the goods. The difficulty is knowing in advance what is likely to be charged.

Customs Duty and Commodity Codes

In addition to VAT, businesses trading internationally need to take into account Customs Duty (and for certain products, Excise Duty as well) that may be charged on imports.

For UK businesses, this means checking with the HMRC and specifying the correct ‘Commodity Code’ for the goods, which will determine how much is charged. Unfortunately, there are thousands of such codes, covering all manner of products, so identifying the right code can take some searching.

@YellowsBestLtd typically imports a range of telecommunications spare parts, and can therefore advise that for similar requirements the following is applicable: Commodity Code: 8517620000

Commodity Code: 8517620000

According to the HMRC website, sales of these goods should have no Duty to pay on imports. It’s less clear what may need to be paid on exports since this will vary by country. The ongoing concern is trying to anticipate these costs in advance, but by making an excessive allowance for them can mean an uncompetitive offer, causing a loss of business.    

Your Experiences and Questions

We’d like to hear about your concerns or practical experiences of international trading, both before and after Brexit, within and beyond the EU. Please get in touch, and let us know how we can help with your continuing business requirements. We look forward to hearing from you.

New Year, New Stock! ‘Dynanet’ Spares

Nokia ‘Dynanet’ PDH Transmission products

For many years, the ‘Dynanet’ family of PDH Transmission telecoms products have well served Public Operator and Private Network Customers across the Telecoms, Utilities, Transport and Public Safety markets with high availability mission critical infrastructure, and indeed some networks are continuing to provide good operational service.

They were first introduced by Nokia over 20 years ago, and were continued in recent years by DNWP. Production of the majority of the product range was ceased in 2019. 

Spare parts for continued operational service

@YellowsBestLtd satisfies world-wide customer product sourcing requirements for current and ‘legacy’ equipment technologies from a wide range of Original Equipment Manufacturers (O.E.M.s).

For the ‘Dynanet’ range, we have recently obtained of a number of additional  refurbished and surplus equipment items. Hence, for those customers continuing to maintain their networks, there now exists the opportunity to increase stocks of spare parts to take advantage of the current availability.

Stocklist of items for immediate supply

Here is a list of the main items currently in stock, though there may be a few additional parts that can be supplied.  Hence, please check and if you do have any requirements, please let us know. We look forward to hearing from you.

Part NumberDescription
CC 24002DB2 2×2 Mb/s Branching Unit (B2), 75ohm
B2
DB2 B2 – CC 24002
Part NumberDescription
CC 24011DB2 2 Mb/s Switching Unit (X2), 75ohm
X2
DB2 X2 – CC 24011
Part NumberDescription
CC 24101DN2 2×2 Mb/s Interface Unit (IU2), 75ohm
IU2
DN2 IU2 – CC 24101
Part NumberDescription
CC 24111DN2 Control Unit (CU), 75 ohm
CG 24170DN2 Bus Power Unit (BPU)
CG 24171DN2 Extended Bus Power Unit (EBPU)
CU 24013Data Interface Unit (DIU) 2M, nx64k: G.703/704, 75ohm
nx64k
DIU nx64k – CU 24013
Part NumberDescription
D-21470Euro Connector, 3×7
3x7
Connector 3×7 – D-21470
Part NumberDescription
D-24204Optical Teleprotection Interface Unit, C37.94
C37.94
C37.94 – D-21470
Part NumberDescription
T31094.01DCN Adapter C4.0
DCNA
DCN Adapter C4.0 – T31094.01
Part NumberDescription
T37870.01NDM 19in 17-slot Subrack
Subrack
19in Subrack – T37870.01
Part NumberDescription
T37871.01NDM DN2 19in 17-Slot Subrack
T37882.02NDM DC Unit (NDUe)
NDUe
NDUe – T37882.02
Part NumberDescription
T37885.01NDM Ring Generator
Ring Generator – T37885.01
Part NumberDescription
T37885.02NDM Ring Generator + DC/DC converter
Ring Generator – T37885.02
Part NumberDescription
T37889.01NDM Backup Unit (NBU)
NDM Backup Unit – T37889.01
Part NumberDescription
T65580.01ACL2i PF GEN Line Terminal Card
ACL2i PF GEN – T65580
Part NumberDescription
TA 21513Optical Line Terminal Repeater (DF2-8), 1300 nm LED MM/SM
TA 21516Optical Line Terminal Repeater (DF2-8), 1300 nm LASER SM
TA 21518Optical Line Terminal Repeater (DF2-8), 1300 nm LASER LP
DF2-8 – TA 21518
Part NumberDescription
TC 21101DM2 Multiplexing Unit, 75ohm
DM2
DM2 – TC 21101
Part NumberDescription
TC 21301DM8 Multiplex Equipment, 75ohm
TC 21705Supervisory Substation
TC 21710.01TMS Adapter
TU 21122.5Data Interface Unit (DIU) 48..64k, V.11, 10ch
TU 21124Data Interface Unit (DIU) nx64k, V.11/V.35/X.21, 2ch
TU 21124.05Data Interface Unit (DIU) nx64k, V.11/V.35/X.21, sync
TU 21125Data Interface Unit (DIU) 48..64k with sync, X.21
DIU X.21 – TU 21125
Part NumberDescription
TU 21205Channel Unit SUB/SUB
TU 21206Channel Unit SUB/SUB
Channel Unit Subscriber / Subscriber – TU 21206
Part NumberDescription
TU 21215Channel Unit SUB/EXCH
TU 21216Channel Unit SUB/EXCH
Channel Unit Subscriber / Exchange – TU 21216
Part NumberDescription
TU 21234.20Channel Unit E&M/VF-P, 10 ch, 20 E&M ch
TU 21236.10Channel Unit 8ch E&M/uP: 1xUKe&m/VF
VF E&M
VF E&M – TU 21236.10
Part NumberDescription
TU 21255.01Channel Switch, 4 port