Time from the sky

When Journal contributor Charles Curry first started using the US-based Global Positioning System (GPS) in the mid-1980s in the oil industry, there were only seven GPS satellites giving just one hour per day when you could get a fix. Nowadays, nearly every smart phone and tablet has a multi-constellation 30-channel Global Navigation Satellite System (GNSS) receiver embedded.

GPS was conceived in 1973 by the US Department of Defence to address defence navigation and the first experimental satellite launched in 1978. Today there are 31 operational GPS satellites orbiting with 24 needed for full coverage. But GPS is not alone. The Russians created their equivalent as did Europe, China, Japan and India with varying degrees of coverage and maturity.

So how does a navigation system disseminate precise time? All GNSS satellites have atomic clocks on board. These are continuously monitored by ground stations and provide the triangulation capability and accuracy for navigation and positioning. (Consider that light travels approximately 30cm in a nanosecond and then one has the basis for slaving a local oscillator to visible GNSS satellites.)

By the mid-1990s GPS started to be used as a timing reference for telecoms. In the UK, BT were the first carrier to adopt GPS to frequency stabilise Rubidium atomic and quartz oscillators at major switch sites. GPS was not the primary reference source; this was, and still is, a cluster of Caesium atomic clocks.

Timing performance can be measured quite easily and displayed using an ITUstandardised metric known as Maximum Time Interval Error – i.e. the time interval error over varying observation periods and relative to a higher stability reference.

GPS is indeed a great achievement and it became somewhat taken for granted. In 1996, when GPS was starting to become accepted as the solution for frequency stability in telecom networks, the time aspect had yet to emerge. However, in the early 2000s, 2G mobile phone technology was emerging which, for some 2G standards, needed precise time at the base station as well as frequency stability. 3G, 4G and 5G also need precise time. Clusters of small cells need to communicate with each other in a synchronous manner which requires precise time at the edge. This need coincided with the transition from Synchronous Digital Hierarchy to Carrier Ethernet-based networks and the development of Synchronous Ethernet to provide traceability to the central reference clocks. An alternative to Synchronous Ethernet is the use of IEEE Precision Timing Protocol as the mechanism for transporting time and frequency over Ethernet networks. Although this is proving a successful technology for frequency, it is not quite so effective for time; it may yet be necessary to deploy GPS at the edge.

GPS at the edge seems the ideal solution but there are a number of issues.

  • The cost of deploying roof antennas is a major concern.
  • Reliability and continuity are critical for mobile networks but, in order to reduce the price of GPS receivers to meet the edge of network cost model, holdover stability is the first casualty, resiliency the second.
  • There is an emerging threat from lowcost GPS jammers which are readily available although their use in the UK contravenes the Wireless Telegraphy Act.
  • Space weather can disrupt the GPS service with unpredictable results.
  • Spoofing is another threat – a concept based on rebroadcasting the GPS signal with different time and position information.

One potential solution, at least for fixed infrastructure, is the terrestrial transmission of a complementary Positioning Navigation and Timing service known as eLoran. It works indoors and is not vulnerable to the same jamming and spoofing threat as GNSS. It does, however, have geographical limitations. eLoran is at a different technology readiness level to GPS and can’t yet be relied upon for synchronisation and timing.

Where will we be in another 10 or 20 years? If the lessons of the past including cost reduction, miniaturisation and technology hybridisation are to be learned we will have eLoran-type receivers embedded in all fixed infrastructure applications. We won’t have to worry about roof antenna installations and the whole thing will be less than a few dollars.

This is an executive summary of the full article by Prof Charles Curry, BEng, CEng, MITP, FIET Charles, Managing Director of Chronos Technology, which appeared in The Journal, Volume 10, Part 1 – 2016. 


NAW 2016: Crissi Williams, ITP apprenticeship scheme

Crissi Williams is Senior Commercial Manager at the ITP and manages the organisation’s apprenticeship scheme. She tells us what it involves…

  1. How does the ITP apprenticeship scheme work? 

The ITP Apprenticeship Scheme is an 18-month course.  Apprentices attend college for a total of eight weeks and learn the rest whilst they are at work earning a living.  An apprenticeship gives young people the opportunity to see what it is really like to work in their chosen industry and once they have completed they also have experience – you don’t get that if you go to University!

  1. What do you look for when recruiting apprentices?

We are not looking for any experience in particular.  We are looking for someone who wants to work in the telecoms industry, demonstrates a knowledge of what it takes         and has a sparkle!

  1. Does the employer get involved in the recruitment process?

Absolutely!  We believe it is imperative that we work with the employer throughout.  The employer provides us with a job description and the ITP will carry out initial screening.  Then we invite the candidates along to an assessment day at the client’s premises where we get to know them through a series of tasks.  We find assessment days a far better way of recruiting apprentices as you get to see how they react in different situations.

  1. How do you support apprentices once they are in post?

We are always on hand to support our apprentices.  We will assist them with any college or work aspect that they ask for help in.  We set up this scheme to give young people more chance – we want them to  succeed!

  1. Why should businesses consider apprentices?

Without new talent, the telecoms industry will struggle – and apprentices are the best solution to that problem.  We aren’t the only people that think that – a recent survey of 500 firms showed that:

  • 77% of employers believe apprenticeships make them more competitive
  • 76% of those employers who employ apprentices agree they make the workplace more productive
  • 81% of consumers favour using a company which takes on apprentices.
  1. How will the new apprenticeship levy affect the telecoms industry?

The new levy will not just affect the telecoms industry, it will affect every industry.  I hope that this will only encourage more employers to give young people a chance!

The ITP apprenticeship scheme is unique and has created more than 50 roles in the telecoms industry since its launch in 2013. Get involved.

NAW 2016 apprentice stories: Michael Lewsey, TATA Communications

Name: Michael LewseyMichael Lewsey photo
Job title: Telecommunications Network Apprentice
Company: TATA Communications

1. How long have you been working as an apprentice?

Since October 2015, so five months.

2. How do you find the role that you’re in?

Through www.apprenticeships.gov.uk

3. What are the benefits of being an apprentice?

The real experience of working with colleagues and being in a working environment is great, as well as the things you learn from other experienced colleagues who always give advice when you face challenges.

4. What do you enjoy most about your job?

Working in a team to complete jobs and the variety of skills I have been picking up from other employees.

5. What would you say to employers who may be considering apprenticeships?

It’s worth it;  young people are more willing and able to learn new skills than most people think.

6. What advice would you give to others looking for an apprenticeship scheme?

Make sure you research, and once you’ve found one you know you’ll enjoy, don’t hesitate to apply for it.

Find out more about the ITP apprenticeship scheme.

NAW 2016 apprentice stories: Joe Kimber, Executive Support, ITP


The ITP’s apprenticeship scheme was launched in 2013 and has since created over 50 different jobs in the telecoms industry. We kickstart National Apprenticeship Week 2016 with an interview with the ITP’s very own apprentice, Joe Kimber. 

Name:  Joe Kimber
Job title:  Executive Support 
Company: ITP

  1. How long have you been working as an apprentice?

I have been in my apprenticeship for 7 months.

  1. How did you find the role you are in?

I found the role on the website Indeed; but I also previously used many other websites such as not going to uni and Reed.

  1. What are the benefits of being an apprentice?

Learning key skills whilst also achieving a qualification after the completion.

  1. What do you enjoy most about your job?

I enjoy having a flexible job specification, this allows me to work on several different projects so my knowledge and understanding will always be developing.

  1. What would you say to employers who may be considering apprenticeships?

I would recommend employing apprentices, as they are keen to learn and are enthusiastic workers.

  1. What advice would you give to others looking for apprenticeship schemes?

It is a great opportunity to gain a greater understanding of work.  I would also recommend setting out a day each week to complete your units, as this will ensure that you will not fall behind in completing your qualification.

The ITP recruit apprentices, with input from employers, and also take care of  administration and training –  providing mentors and assessors throughout the apprentice’s journey. For more information about the scheme please see www.theitp.org/itp_apprentices

ITP launches Ninth Annual Apprentice Awards during National Apprenticeship Week

Celebrating their ninth year, the ITP Apprentice Awards will open for entries during National AWARD IMAGEApprenticeship Week  (14th – 18th March 2016) -offering employers the chance to recognise talent within the telecoms industry.

Who are they open to? 

They are open to all apprentice members of the ITP including those on the ITP’s own Apprenticeship Scheme, which was launched in 2013 in response to the demand for specific telecoms apprentices.

Did you know…

  • The scheme has created more than 50 jobs in the telecoms industry since its launch.
  • The scheme is unique in the fact that it helps organisations to recruit, train, mentor and support apprentices throughout their career journey.
  • Works with SME employers, including Level 3 Communications, Green Telecom, Sematron and Horizon Telecom amongst others.
  • Past apprentices have gone on to be nominated for national apprentice awards, Freemans Guild awards and have undertaken further training to degree level with the support of their employer.

What are the categories? 

The ITP awards recognise those who have excelled as part of the Apprenticeship Scheme. Categories include:

  • Apprentice of the Year in 4 categories: SME Apprentice of the Year, Intermediate, Advanced and Higher Apprentice of the Year, and The Christopher Mills Award.
  • Other categories on the night include Mentor of the Year and The Chris Seymour Award for Women in Telecoms.

The prestigious ceremony will take place on the 7th December at The Radisson Blu Hotel, Portman Square.

SME Apprentice of the year 2015 winner James Tuck told us “My greatest achievement before winning the award was finding an apprenticeship in the industry I love with a brilliant company, surrounded by an excellent team of people who want to help me succeed. Winning the award is just the icing on the cake.”

How can you enter? 

Apprentices can apply via the ITP site at https://www.theitp.org/itp_apprentices/apprentices/itp_awards.

Managers wishing to nominate an apprentice should contact apprentice@theitp.org

ITP members go behind the scenes at the BBC

Twenty-two ITP members were recently treated to a behind the scenes look at the BBC and Salford University as part of our quarterly ‘Insight’ days.

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The tour included backstage access to the BBC Breakfast studio, the BBC’s largest soundstage, one of the biggest studios in Europe (where The Voice is filmed), a sneak peek at future technology (OLED / drones etc), and a visit to the Radio 5 Live studio. Members heard how the site is managed, and how the telecoms systems are operated.  The day ended with a visit to the University of Salford’s campus where they teach future BBC employees.
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ITP CEO Adam Oliver said “It was fascinating to see how the BBC manages such a large and complex site, and to understand the role of telecoms within this vast organisation. I’m delighted to have been able to give our members this unique opportunity.”
Insight events are available to members on a quarterly basis. For a list of upcoming events visit: https://www.theitp.org/calendar/

For all the photos from the day, see our Facebook album.