The importance of a low noise floor


Alan Wheable TV-Bay Magazine
Read ezine online

The Noise Floor of a piece of T&M equipment is the inherent noise (or intrinsic jitter) introduced by the equipment itself. The level of inherent noise affects the accuracy and repeatability of jitter measurements that can be made, especially when measuring low levels of jitter. With the permitted 100KHz jitter on a 12G-SDI signal being only 0.3UI, it is important to establish the total level of jitter in the signal path to ensure that it does not exceed this limit and cause data errors.

Jitter can be assumed to be additive so the inherent noise of the measurement circuit is added to the jitter on the SDI signal itself. The effect of the inherent noise is to increase the width and shape of the Gaussian distribution obtained when analysing Random Jitter.

Random Jitter is noise that cannot be predicted as it has no discernible predictable pattern and due to its random nature will have a typical Gaussian distribution over time as seen on a jitter histogram.

The measured jitter is effectively the peak to peak value obtained from the Gaussian distribution of samples. The spread of the Gaussian distribution is determined by the level of jitter on the signal and the time taken to measure the jitter (i.e. the number of jitter samples made within the sample period). Ideally the sample period should be infinite to capture all of the possible random jitter events, but this is not practical so typically measurement is made by capturing in excess of 50,000,000 independent samples, multiple times per second then aggregating sample sets to provide the jitter value.

If the Noise Floor is higher than the SDI signal jitter, then it can be difficult to accurately measure the signal jitter is due to the combined SDI signal jitter and the Noise Floor. Here the Gaussian distribution will be wide compared to that of a low Noise Floor, where the Gaussian distribution will be narrower. The peak to peak value, over an infinite sample period, is effectively the same for both high or low Noise Floors. Over short time spans, however, subsequence measurements may be different due to the random nature of jitter.

With more and more 12G-SDI equipment and converter boxes on the market, some without the re-clocking stipulated by SMPTE, the need to be able to accurately measure the accumulated Jitter Transfer in the signal path is vital.

The Omnitek Ultra 4K Tool Box was the first on the market back in September 2015 with the only viable 12G-SDI Physical Layer Analysis measurement equipment which used the chip technology available at that time. The latest generation of the Omnitek Ultra 4K Tool Box (Model G) benefits from the latest chip technology so now the Ultra 4K Tool Box can once again boast the lowest Noise Floor of any currently available T&M equipment of its type. This benefits new, and existing, customers alike as they can get the best possible jitter measurement.

The new Model G has a lower Noise Floor compared to competing solutions, and previous models, which means that lower levels of 12G-SDI signal jitter can be more reliably measured with improved repeatability. The new circuit design minimises the need for unit calibration, reduces the calibration cost and therefore reduces the cost of ownership. There is an upgrade path available to all existing customers of Ultra 4K Tool Boxes with the 12G-SDI and PHY options. Contact a local Omnitek dealer or by visit the Omnitek web site for details.


Tags: iss119 | omnitek | test and measurement | intrinsic jitter | Alan Wheable
Contributing Author Alan Wheable

Read this article in the tv-bay digital magazine
Article Copyright tv-bay limited. All trademarks recognised.
Reproduction of the content strictly prohibited without written consent.

Related Interviews
  • Omnitek Updates for Ultra 4k Toolbox at NAB 2018

    Omnitek Updates for Ultra 4k Toolbox at NAB 2018

  • Omnitek Ultra TQ at IBC 2017

    Omnitek Ultra TQ at IBC 2017

  • Omnitek Consultancy and Design Services at IBC 2017

    Omnitek Consultancy and Design Services at IBC 2017

  • Omnitek at IBC 2016

    Omnitek at IBC 2016

  • Omnitek at NAB 2016

    Omnitek at NAB 2016

  • Omnitek at BVE 2016

    Omnitek at BVE 2016

  • Omnitek Ultra 4K Tool Box at IBC 2015

    Omnitek Ultra 4K Tool Box at IBC 2015

  • Phabrix RX2000 at NAB 2013

    Phabrix RX2000 at NAB 2013

  • Phabrix at BVE 2012

    Phabrix at BVE 2012

  • Sencore at IBC2011

    Sencore at IBC2011

  • Leader at IBC2011

    Leader at IBC2011

  • Murraypro at IBC2011

    Murraypro at IBC2011

  • Hamlet at IBC2011

    Hamlet at IBC2011

  • Tektronix at IBC2011

    Tektronix at IBC2011

  • Phabrix at IBC2011

    Phabrix at IBC2011


Articles
The Future of Broadcast Technology
Sebastian Richter

Spotlight on Sebastian Richter, Vice President Media Systems at Rohde & Schwarz.

We are currently in the middle of a transition phase with migration to several new technologies, from the move to IP-based infrastructure and the shift from linear to video-on-demand (VOD).
The question for all of us is how long that transition phase will last; it is going to be faster for some customers then for others – national broadcasters, for example – it will be a slower process.

Tags: broadcast | 5g | 5g broadcast | rohde and schwarz | Sebastian Richter
Contributing Author Sebastian Richter Click to read
Spotlight on James Gilbert, Director of Product and Solution Management
James Gilbert

Over the next eight years we are going to be in transition, and within that there will be vastly different rates of change among content owners and media organisations. As a technology provider the onus is on us to be flexible and adaptable to meet this wide range of requirements from our customers.

Tags: | James Gilbert
Contributing Author James Gilbert Click to read
Spotlight on Karl Mehring, Director of Professional Services, Broadcast, Amplifier and Media
Karl Mehring

How has the role of Professional Services evolved in recent years and what vision do you have of the broadcast technology business? Covering new opportunities that the move to remote brings, new technologies such as 5G broadcast & the impact on the broadcast industry, and the challenges for broadcasters and how can they overcome them.

Tags: COTS | cloud | remote production | distribution | 5g broadcast | Karl Mehring
Contributing Author Karl Mehring Click to read
The Future of Broadcast Technology
Manfred Reitmeier

Now that OTT and VOD have become more mainstream, many commentators talk about traditional broadcast methods, like terrestrial transmission, being a thing of the past. With so many new platforms and non-traditional content services carving out a growing slice of the market, you can be forgiven for thinking that linear over-the-air television is on its way out. The reality is that the industry must strike a balance between meeting consumers’ shifting habits and the business and operational needs of content providers.

Tags: Rohde Schwarz | 5g broadcast | Manfred Reitmeier
Contributing Author Manfred Reitmeier Click to read
A switch in time: how KVM can unlock the future of broadcasting
Chris Smeeton

One of the major changes for broadcasters during the pandemic has been the shift towards remote production; by no means a new phenomenon in an IP environment, yet accelerated under lockdown to accommodate travel and gathering restrictions. A 2021 report found that almost 40% of broadcast professionals now employ remote production, up 9% on the previous year.

Tags: KVM | ARGOSY | GDSYS | KVM Tech | Chris Smeeton
Contributing Author Chris Smeeton Click to read