Regarding the current situation in Ukraine

AGC Systems strives to conduct business at the highest level of competence, fairness, and ethics.  We routinely evaluate our relationship with customers, clients, and sponsors, and consider whether any change is needed in those relationships.

We are horrified at the current situation in Ukraine, and condemn its invasion by Russian military forces. 

It has come to our attention that one of our sponsors is known to have headquarters in Russia. While we are led to understand that they have no connection with the Russian government or any person or entity under U.S. and European sanctions, we cannot ignore the fact that the net result of our endorsement of the company and its products would be financial input into the Russian economy.

In addition, the State of New Jersey has enacted laws limiting or prohibiting dealings with businesses associated with Belarus or Russia.

For these reasons, and as a show of support for both the government and people of Ukraine and the governments of the United States and the State of New Jersey, we are immediately suspending endorsement and promotion of that company and its products and services. If any of these factors should change in a positive fashion, we will reconsider our position.

I know that all of my colleagues here and around the world pray for peace and are against all types of violence whatsoever.

Aldo Cugnini
President, AGC Systems LLC

8 March 2022

Image Stacking — Sky & Telescope, April 2022 — Errata

The following errata correct the April 2022 Sky & Telescope Article, Image Stacking Demystified, by Richard S. Wright, Jr.

  1. Mathematically, the shot noise from the imager and associated electronics can be considered to be added to the signal.
  2. The shot noise is proportional to the square root of the number of frames being stacked.
  3. The horizontal axis in both graphs on p.56 should be labeled “number of stacked frames,” and the vertical axis should be labeled “quantity.”

EXPLANATION

  1. The S&T author writes, “It’s important to bear in mind that this noise is not something that gets added so much as something that’s missing.” This is incorrect.  The mathematical modelling and analysis of signals with noise accounts for each of these elements as an added component; there is nothing “missing” from the original signal, which still exists in the image capture.  In practice, this can be readily seen by using a spectrum analyzer, which will show that the signal and noise are separate components.  The shot noise from the imager and associated electronics should be considered to be added to the signal.
  2. The S&T author writes, “Shot noise is also quantifiable — it’s simply the square root of the signal value.” This is incorrect, as are the numerical examples that follow the statement.1 The noise and signal components are separate entities, and one cannot say that one of them is a function (square root) of the other.  (Actually, some systems do have an interaction between the two, but those are usually 2nd-order, minor effects, and are not relevant in the image stacking situation.)  The noise value is completely determined by the physics of the imaging device and the transistors in the related electronics, and is independent of the signal – it’s even there when there is no signal (e.g., a dark frame).  The incorrect statement would imply that a dark frame has zero noise, which is not true: in addition to fixed pattern noise (which we can reduce by subtracting a dark frame when doing advanced image processing), the dark frame will have its own random noise, too.

What is really happening is the following.  When we stack multiple images, we are literally adding the images together, pixel-by-pixel.  That means that the signal components get added together, and so do the noise components.  When the images are properly aligned (registered), the signal components at each pixel from one frame to the next add together as correlated data, since they are part of the same image. This combination is literally a simple addition, so image stacking increases the signal component in proportion to the number of frames being stacked.

However, the noise component at each pixel from frame to frame is uncorrelated, because it is a random process.  The noise components add together as orthogonal vectors, which means that the noise value increases by the square root of the number of frames being added together.  (The stacked images are then re-scaled, so that the resulting image doesn’t get progressively brighter everywhere – but this, of course, scales the noise by the same amount.)  The signal-to-noise ratio improvement is therefore proportional to the square-root of the number of frames that are stacked.

  1. The graphs on p.56 are labeled incorrectly. The horizontal axis in both graphs should be labeled “number of stacked frames,” and the vertical axis should be labeled “quantity,” as it represents either signal or noise in the left-hand graph, and signal-to-noise ratio in the right-hand graph.

—agc


FOOTNOTE (1):

There is a different quantity, known as photon noise, which is characterized as the square root of the photon signal, but this is not the dominant factor in our calculation of signal-to-noise ratio, because we are considering the net effect over a set of stacked frames.


REFERENCES:

Wikipedia: Shot Noise – note the discussion regarding “square root of the expected number of events.”

Wikipedia: Gaussian Noise – “values at any pair of times are identically distributed and statistically independent (and hence uncorrelated).”

Philippe Cattin, Image Restoration: Introduction to Signal and Image Processing.

Robert Fisher, et al, Image Synthesis — Noise Generation.

 

 

ITU-R PUBLISHES TWO DOCUMENTS on PLANNING and TESTING of ATSC 3.0 SERVICE

AGC Systems Key Participant in ITU-R Rapporteur Group and ATSC Planning Teams

The International Telecommunications Union (ITU) has published two new documents that support the planning and testing of ATSC 3.0 systems.  The documents are:

  • ITU-R Recommendation BT.2033-2 : Planning criteria, including protection ratios, for second generation of digital terrestrial television broadcasting systems in the VHF/UHF bands.
  • ITU-R Report BT.2495 : Methods for laboratory and field measurements for the assessment of ATSC 3.0 reception quality.

This brings the total number of new ATSC-related documents to five, which includes the Handbook on Digital Terrestrial Television Broadcasting networks and systems implementation, which was updated last year.

Several ATSC-3.0-related documents are also in the ITU-R deliberation process, which are expected to result in additional publications. AGC Systems has been involved in this process for several years, and leads several initiatives to develop these documents.


The International Telecommunication Union is the United Nations specialized agency for information and communication technologies (ICTs). Founded in 1865 to facilitate international connectivity in communications networks, ITU allocates global radio spectrum and satellite orbits, develops technical standards that ensure networks and technologies seamlessly interconnect, and strives to improve access to ICTs to underserved communities worldwide.

The Advanced Television Systems Committee, Inc. is an international, non-profit organization developing voluntary standards for digital television.  ATSC member organizations represent the broadcast, broadcast equipment, motion picture, consumer electronics, computer, cable, satellite, and semiconductor industries.  The ATSC mission is to create and foster implementation of voluntary Standards and Recommended Practices to advance terrestrial digital television broadcasting, and to facilitate interoperability with other media.

# # #

WNET Group will be First NEXTGenTV Broadcaster in New York City

The WNET Group has announced plans to launch NEXTGEN TV service in New York City and surrounding areas – the #1 television market in the country encompassing approximately 7.45 million TV households.

AGC Systems is one of the key organizations supporting The WNET Group with extensive engineering testing and operational planning based on the ATSC 3.0 suite of NextGenTV technologies.

Neal Shapiro, President & CEO of The WNET Group, expects that this transition “will modernize the New York City broadcast market infrastructure to deliver high-quality broadcasts with the latest technology available.”

For more information, see the WNET Press Release.

# # #

KEY ATSC 3.0 TECHNOLOGIES SELECTED BY BRAZIL

The Fórum Sistema Brasileiro TV Digital Terrestre (SBTVD Forum) has recommended to the Brazilian government the selection of several technologies proposed by ATSC for Brazil’s next-generation terrestrial digital television standard.  AGC Systems has been actively involved in the proposal and testing process, on behalf of several clients, resulting in adoption of the SL-HDR1 High Dynamic Range system and MPEG-H Audio coding.

ATSC President Madeleine Noland congratulated the ATSC IT-4 Brazil Implementation Team, of which AGC Systems’ Aldo Cugnini is a member. “IT-4 members have been diligently supporting ATSC technologies throughout the process and will continue their efforts in the upcoming phases of the SBTVD evaluation process.”

The SBTVD development of “TV 3.0” specifications and additional testing will continue over the course of the next two years.

For more information, see the ATSC Press Release.

# # #

Cugnini to Present Talk on New Audio/Video Technologies

AGC Systems’ President Aldo Cugnini will deliver an online talk, entitled “New Audio/Video/Wireless Technologies For Home Entertainment.”  Scheduled for Thursday, November 18, 2021, 6:30PM EST, and hosted by the IEEE Consultants’ Network of Northern New Jersey, the talk will explain how new technologies like UHDTV, HDR, and HEVC enable audio and video devices to efficiently deliver the latest entertainment to consumers.

The talk is free, and can be accessed by registering here.


This presentation is partly sponsored by Elecard.  Click here for more information on their video and stream analysis tools.

FCC Proposes to Reinstate Amateur Radio Service Fees

The FCC has proposed in an NPRM to impose license fees on Radio Amateurs.  I urge you to send your comments to the FCC arguing against the reinstatement of those license fees.

You may not be aware of the public good this service provides in times of emergency, as it has during the recent hurricanes.  The decrease of new applicants in recent years is not helped by this mercenary proposal.

You may also not know that amateur radio is often a leading developer of new technologies.  Just one example is the recent development of a low-cost vector network analyzer — the NanoVNA.  Originally developed by and for radio amateurs, this breakthrough device is now being used in the broadcast and other wireless industries, as written up by broadcast engineer Doug Lung in the last two issues of IEEE BTS Magazine and in TV Technology.

The NPRM can be found at FCC MD Docket No. 20-270Comments are due by November 16, 2020.

The ARRL will be filing comments, and their position can be found at this link; you may be interested to see my filed comments.

73’s,

Aldo, W2AGC

Video Pioneers Remember Historic HDTV Debut

Grand Alliance Prototype

Twenty-five years ago this week, the world’s first HDTV broadcast system was unveiled in Las Vegas at the 1995 NAB Show.  AGC Systems’ Aldo Cugnini was there, as one of the many engineers who developed the “Grand Alliance” digital HDTV system.  Then at Philips, Aldo had a leadership role in the system’s development, which went on to become the ATSC digital television system.

Click here to see historic videos of the debut of HDTV.