Feedback
Apr 1, 2010 12:00 PM
Thoughts and viewpoints from Broadcast Engineering’s readers.
Aspect ratio clarification
Dear editor:
I am writing in response to a letter from Paul in the Feedback department of your February 2010 edition. I have no issue with Paul's personal opinion on aspect ratio and his conclusion in favor of a 4:3 aspect ratio for television. However, I feel that, for the record, some significant errors should be corrected.
The first error resides with Paul's statement: “My use of the word ‘gimmick’ is appropriate because it added nothing of real value, only extra background as the real action was still confined to the central 4:3 area.”
Nothing could be further from reality, as hundreds of major movies have fully exploited (and still do) the entire widescreen — in highly creative ways — with all sorts of action. Has Paul not heard of the sophisticated “pan and scan” function of the global telecines that transfer film-based movies to TV video, where they must track that action across the wider screens in order to judiciously extract his favorite 4:3 portion?
The second error is in Paul's statement: “I fail to understand the TV industry fascination with 16:9.”
This failure is probably because (a) Paul never participated in any of the standardization working groups back in the 1980s that produced the 16:9 standard for widescreen HDTV and SDTV; nor (b) did he ever study the highly learned research papers that validated the move to a wider screen in the new era of HDTV. This was psychophysical research on large numbers of humans that clearly established a preference for a wider screen. I would suggest that Paul find and read just one of these papers, perhaps starting with “Psychophysical Analysis of the Sensation of Reality Induced by a Visual Wide Field Display” by Hatada, Sakata and Kusaka (SMPTE Journal, August 1980).
The last error is within Paul's statement: “Most paintings from the great masters to modern works are approximately 4:3.”
Here, Paul is guilty of a significant inexactitude. I would gently suggest that he return to any major art gallery and take a more careful look.
Larry Thorpe
Canon
Ridgefield Park, NJ
Thinnet networks
Dear Brad Gilmer:
In your February 2010 article on networking hardware, you write:
“While RG-58 was much easier to work with … it required a BNC T and a 50V terminator on the back of every card, and you had to shut down the network to install or remove computers from the network.”
This is inaccurate. A bus topology thinnet network only requires a total of two 50V terminators, one on the BNC T of the first device on the bus, and one on the last device. Devices in the middle do not require termination because they have network cable connected to both legs of the T connector. This is why they are called terminators; they terminate the bus and stop signal reflection from the end of the cable.
Also, it is incorrect to state that the network had to be shut down for nodes to be removed or attached. This is true only if you have to physically disconnect the cable to insert a BNC T connector. Where existing T connectors are in place, nodes can be inserted and removed without any interruption in the network.
And finally, why are the features of the vampire tap and MAU labeled in German?
Jamie Campbell
Brad Gilmer responds:
Well spotted! You are absolutely correct. On 10BASE-T networks, a terminator is required only at the beginning and end of the network. There is a BNC T on the back of every NIC card. The RG-58 cable daisy-chains from one computer to the next via the T connectors. At the ends, a 50V terminator is required, as you correctly state, to eliminate reflections.
You are also correct to state that if you have had the foresight to install T connectors where you need computers in the future, then you do not need to shut down the network. Unfortunately, I never was smart enough to figure out six months or a year early where our network would need to be. In this case, the information in the article is correct: You have to break the network to add a computer, something you do not have to do with more modern networks.
In regard to the vampire tap, the picture of the vampire tap has German captions because vampire taps are so old that this is the only picture I could find that illustrated the connections I referred to in the article.
Thanks so much for your helpful comments and the correction regarding the terminators. I hope you find this column useful.
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