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Mobile Evolution and the Extinction Event

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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. 

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Legacy Transmission & Line Codes

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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+x7 , 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 brief run-through of legacy tranmission 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. 

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Lessons from the ‘Lockdowns’ for Business

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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.

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International Trading (Post Brexit)

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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.

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New Year, New Stock! ‘Dynanet’ Spares

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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
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Season’s Greetings

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It has been an unexpectedly challenging year, unprecedented times indeed!

Unfortunately, it seems likely that we will face more difficulties ahead. The global pandemic still needs to be beaten, and the U.K. leaving the EU will result in unpredictable trading conditions.

Having just celebrated our fifth anniversary, YellowsBest looks forward to continue working with our partners and assisting Customers’ businesses through the uncertain times ahead.

We wish you all the best for a safe, seasonal celebration.

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Celebrating our fifth anniversary!

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Five years of successful trading! Thanks to all our Customers and Suppliers.

@YellowsBestLtd has been in business for five years.

5 years of trading
5 years of trading

Our aim continues to be “Keeping Customers Operational”; understanding requirements and fulfilling them by providing a range of management services and solutions, including:

  • consultancy, for business development, sales and marketing
  • technical support, onsite engineering or 24/7 NOC remote assistance
  • systems supply, including legacy IT servers / workstations
  • spares for infrastructure, such as telecoms and CCTV cameras
  • repairs at module and component level, e.g. LED displayboards, PSUs
  • value recovery through reverse logistics, resale and recycling

As we continue to move forward, we’d very much like to understand what other services and solutions we can provide to our existing Customers, as well as what would be of interest to potential clients. We’re always keen to enhance our range of #business services, increase the #enterprise infrastructure we support and expand our mix of #sustainable solutions we offer for supply and maintenance of new and legacy #technologies and products.

Please get in touch to discuss your challenges; whether you’re implementing new systems or maintaining existing infrastructure to serve your operational business needs. We look forward to hearing from you.

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Maintenance of Legacy networks – Spares, Connectors and Cables

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Continued use of Legacy Telecoms  – Nokia PDH ‘Dynanet’

Public Operator and Private Network Customers across the Telecoms, Utilities, Transport and Public Safety markets maintain ‘legacy’ infrastructure for mission critical applications, which continue to deliver good operational service with high availability. 

Typical products utilised are those from the ‘Dynanet’ family of PDH Transmission telecoms products, which 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. 

In order to maintain these systems and networks, it’s still possible to supply spares from surplus stocks and refurbished items to keep networks operational. 

Don’t forget the Connectors and Cables!

One challenge for the continued use of existing infrastructure, particularly when installing replacement parts, is sourcing the appropriate specialised and often propriety connectors for cabling of interfaces and management connections.  

Regarding ‘Dynanet’, fortunately some products can still be produced, notably the Euro / SMB connectors, along with the DCN Adapter C4.0, related management software products and other items such as the TPS64 and NDUE. Listed here are a few of those currently available new:

Part NumberDescription
21475
SMB Connector for RD179 cable
21472
Euro Connector 3×32
21470
Euro Connector 3×7
Euro Connector 3×7 – 21470
Part NumberDescription
24201TPS Control Unit
24202TPS Channel Unit
T37882.02NDM DC Unit, enhanced (NDUE)
T31094.01DCN Adapter C4.0
DCNA
DCN Adapter C4.0 – T31094.01

We are able additionally produce a wide range of cable products to suit most connection requirements, utilising our UK-based manufacturing partner.  Bespoke cable assemblies, control boxes, harnesses, wiring looms, panels, fibre optic products are some of the network solutions available. 

@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), surplus stocks and refurbished items.

Hence, please check and if you do have any requirements, please let us know. We look forward to hearing from you.

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Solar Power – eCharger project – UPDATE #2

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FIX & UPGRADE – Restoration and increase of Solar Panel energy production

Project Re-cap

The project from 2 years ago, detailed here, built a solar energy charger using these system elements:  Solar Panel, Charge Controller, Battery, Inverter. Last year, an upgrade was performed to increase the batteries to provide more storage capacity, as described in Update #1.

Solar Panel Failure

The system has operated satisfactorily for almost exactly 2 years, but then it was observed that no energy was being produced. After investigation, it was discovered that the solar panel had developed a fault. The panel was a flexible’ model, and by slightly bending it, energy was intermittently produced. Hence clearly there was an internal breakdown of connectivity. 

Solar Panel Replacement & Upgrade

Since a replacement was needed, it was decided to purchase a more robust, ‘fixed (i.e. non-flexible) solar panel, which has a solid frame and securely mount onto a brick wall. Taking advantage of the overall lower cost of fixed vs flexi panels, it was decided to opt for an increase to 100W for the replacement.

RatingInformation
Rating Information

This will bring the advantage of producing more energy during sunny periods, which will compensate for the need to mount the panel on a wall where it receives slightly less direct sunlight hours. 

100W Solar Panel
100W Solar Panel (mounted)

The installation of the replacement panel was relatively straight-forward, using ‘Z-brackets’ to affix to the wall.

zbrackets
Z Brackets

It came with MC-4 connector terminated cable ‘tails’, which were plugged into the existing positive and negative connections.

Connector Block & MC4 tails
Connector Block & MC4 tails

Power generation was resumed immediately, with an extremely healthy 4A (roughly double of the previous 50W panel, as expected) confirming the success of the remedy. 

Charge Display
Charge Display

Conclusions

Alas, it transpires that the originally chosen ‘flexi’ type of solar panel is not very ‘robust’ and consequently is only warranted for 1 year. It is somewhat disappointing that only such a short life-span is achieved, especially since it had been mounted on shed-type roof without experiencing disturbance or damage. 

Happily, the replacement ‘fixed’ type of solar panel is warranted for 10 years, so should operate for a considerably longer time. And given that like-for-like it is less expensive, then it is concluded that this should be selected to ensure maximum lifetime and collection capacity for the same outlay. 

@YellowsBestLtd we are always looking to expand our portfolio services for #business development and #enterprise support, and increase the mix of solutions for #sustainable systems and maintenance of new and legacy #technologies and products for our customers. Please get in touch to discuss your requirements; we look forward to hearing from you.

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Remaining stocks of Nokia ‘Dynanet’ spares – Update

Posted on by Bernard Smart — No Comments ↓

Surplus and Refurbished Items for continued operational service

Many Customers have ‘legacy’ telecommunications networks which are continuing to provide good operational service. Particularly where functional requirements have not changed, it makes sense to avoid or delay costly and time-consuming change-out replacement projects, by obtaining spare parts.

@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).

Stocklist of Nokia ‘Dynanet’ Spare Parts – Available for immediate supply

For the ‘Dynanet’ family of PDH Transmission telecoms products, which has provided 20+ years of service, we still have a few spare units are in stock and available for immediate supply. These items have been mostly retrieved from operational service during Customers’ decommissioning projects, and have been refurbished, tested and are warranted for working operation.

Given that production of the majority of the product range was ceased in 2019 or before, it is recommended to consider purchasing spare parts whilst there is still availability.

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
CC 24011DB2 2 Mb/s Switching Unit (X2), 75ohm
CC 24101DN2 2×2 Mb/s Interface Unit (IU2), 75ohm
CC 24111DN2 Control Unit (CU), 75 ohm
CF 24186DN2 19in Subrack
CF 24186.09DN2 19in Subrack, grey-L91 EMC
CG 24170DN2 Bus Power Unit (BPU)
CG 24171DN2 Extended Bus Power Unit (EBPU)
CU 24013Data Interface Unit (DIU) 2M, nx64k: G.703/704, 75ohm
D-21470Euro Connector, 3×7
D-24204Optical Teleprotection Interface Unit, C37.94
T30506.0917-slot DYNANET Subrack
T30851.02Subrack Power Adapter (SPA)
T31094.01DCN Adapter C4.0
DCNA
DCN Adapter C4.0 – T31094.01
Part NumberDescription
T37870.01NDM 19in 17-slot Subrack
T37871.01NDM DN2 19in 17-Slot Subrack
T37882.01NDM DC Unit (NDU)
T37882.02NDM DC Unit (NDUe)
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
T65520.01ACL2 RM DC Power Gen
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
TC 21301DM8 Multiplex Equipment, 75ohm
TC 21705Supervisory Substation
TC 21710.01TMS Adapter
TG 21261Ring Generator 25HZ 15W
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: 2xe&m/vf
TU 21255.01Channel Switch, 4 port
TV 21640.08Power Interface Adapter DC
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