Television

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Selecting the Right Television

Summary

Although most electronics are available with satisfactory performance in DCDirect current models, televisions (TVTelevision) are a different matter. Miniature TVs are available in DC but larger ones are all ACAlternating current. There are many different technical specifications between TVs but the goal for you and your guests is simply the experience of picture quality or what is called presence.

In a small sailboat or cruiser you are likely to prefer a DC model designed for recreational vehicles. In a larger powered boat, with a goal of minimising AC consumption and inverter size, a 50-inch 720-pixel (720p) LEDLight emitting diode-LCDLiquid crystal display with a 9-foot (ftFoot) viewing distance is probably optimum. Plasma delivers a better experience but is losing the market because LED-LCD is cheaper to manufacture and can deliver higher resolutions, with less energy consumption.

Displaymate has an excellent report discussing how to evaluate TV displays.

Television Types

There are four prevalent types of technology used by high-definition televisions (HDTVHigh-definition television):

• Plasma—Plasmas use ultraviolet (UVUltraviolet) light created by igniting pockets of gas to excite red, green, and blue phosphors in the screen.
• LCD—(Liquid Crystal Display) use color filters and LCDs to block or reveal light from an additional cold cathode fluorescent (CCFCold cathode fluorescent) backlight.
• LED-LCD—(Liquid Crystal Display-Light Emitting Diode) HDTVs use LED backlighting instead of the cold cathode fluorescent backlighting used by most other LCD.
• OLED—(Organic Light-Emitting Diode) passes electricity through certain organic materials that glow in red, green, and blue to create a TV image. No other TV technology creates light directly like this.

LCD with CCF are no longer manufactured and are only available used.

Over the Air

Over the air (OTAOver the air) reception requires an antenna or satellite dish and a tuner in the TV or a separate component. AAmpere (amp), SI unit of electrical current separate component will give the most flexibility. Historically for analogue broadcasts each country used one of three different broadcast standards: NTSC in North, Central and Andean South America; SECAM in France, the former USSR and Central West Africa; and PAL in Europe and most of the rest of the world.

However, the world is moving to Digital television (DTVDigital television) and proliferating an even larger number of standards. Most DTV OTA direct transmissions are low power and only useful at maximum distances of ~30 miles. The world is moving to streaming video via Internet and less and less by cable. Marine applications typically use satellite.

The DTV OTA standard in North America is ATSC.

Picture Quality

The most important aspects of picture quality are:

1. Contrast ratio
2. Colour saturation
3. Colour accuracy
4. Resolution

Although resolution is ranked fourth, the place to start is with resolution versus the size of the cabin, available space to locate the TV, and the viewing distance for your guests. In general, pick the largest flat-panel screen size that will fit comfortably into the space, subject to an affordable resolution, measured in pixels, for the viewing distance. TV screens are measured diagonally, and they range in size from fewer than 20 inches to more than 80 inches. For a given cost, a smaller higher resolution screen will give a more pleasurable experience than a larger lower resolution one, but you will have to sit closer. Overall, resolution trumps size. However, the devil is in the details.

If you have a super large cabin, you will want to consider a drop-down screen and an LCD, DLPDigital light processing or LCOSLiquid crystal on silicon projector instead of a flat-panel TV.

Resolution and Optimal Display Size

The optimal viewing distances at which the human eye can best process the details in a HDTV resolution is called the Lechner distance.

This can be confusing. The higher the resolution, the closer you need to sit to see all the detail in the image (details are smaller). There are specific distances at which the human eye has the best chance of processing all of the detail that HDTV resolution has to offer. At greater distances a 720p TV may be a better choice. An ultra-high definition 4k TV will have you sitting a few feet from a huge screen, craning your neck upwards, just like in the front row of the movie theatre.

Different types of TV have different capabilities in resolution:

• LED-LCD is easier to manufacture in higher resolutions
• Plasma has limits

According to Lechner the average home viewer sits 9 ft (2.7 mMetre, SI unit of length) from the TV and an optimum 1080 TV size at this distance would be 69 inches (180 cmCentimetre). The optimal viewing distance to a 42 inch (110 cm) 1080 HDHigh definition TV would be 5.5 feet (170 cm).

In practice it'sSecond probably easiest to figure out the location of the TV and seating arrangement in the cabin, and use the viewing distance to select an optimal TV size and resolution from Table 1 or 2 below.

Table 1 - 1080p Resolution

Viewing Distance		TV Size
feet	metres	inches
4.5	1.37	32
5.0	1.52	37
6.0	1.83	42
6.5	1.98	46
7.0	2.13	50
7.5	2.29	55
8.5	2.59	60
9.0	2.74	65
9.5	2.90	70
10.5	3.20	75

You can also approximate this for 1080p with the formula:

TV Size [inches] = (Viewing distance [ft]/1.6)*12

Table 2 gives size and distance for 720p resolution.

Table 2 - 720p Resolution

Viewing Distance		TV Size
feet	metres	inches
6.5	1.98	32
7.0	2.13	37
8.0	2.44	42
8.5	2.59	46
9.5	2.90	50
10.5	2.20	55
11.5	3.51	60
12.2	3.73	65

Contrast Ratio

The contrast ratio of a TV screen is the ratio of the luminance of white and black. A high contrast ratio is desirable. Because TVs can mostly achieve the same brightness of white, the contrast ratio really represents how dark black will be, and a higher number will mean darker blacks instead of a washed-out grey. Contrast is difficult to measure and manufacturers exaggerate so check the findings of reviewers.

On your TV, contrast controls only the bright parts of the image. Set this too high, and you’ll wash out detail in clouds, snow, etc. Set it too low, and the image will look flat and dark.

Different types of TV have different contrast profiles. CNET recommends:

• Plasma if you watch TV in a dark room or at night because the added contrast of plasma will be very cinematic
• LED-LCD if you watch a lot of TV during the day because of its brightness
• LED-LCD with some kind of local or zone dimming for intra-scene contrast ratio and good light output

The picture quality of plasma and LCD is very similar but plasma panels are known for their better contrast ratios, rendering of rich colors and deeper blacks. Plasma screens are available in larger sizes and have a better refresh rate, which makes them better for action viewing and sports with little to no ghosting effects. Plasma screens can suffer from burn-in caused by static images such as logos down in the corner.

LCD is well known for motion blur. LCDs can show ‘ghosting’ trailing after a fast-moving image.

However, LCD has taken over the market and are made in a wider range of sizes than plasma screens. The sweet spot targeted by LCD manufacturers is 42 to 50 inches.

The viewing angle of both is similar. However, the image quality of a plasma TV is good when viewed off to the side; whereas an LCD TV will lose contrast or brightness and colour accuracy. This is an important consideration in a salon with fixed furniture. If you have a wide viewing area plasma will give a better experience. But overall, LCDs are up to four times brighter, so better for daytime viewing.

Colour Saturation

Saturation is an aspect of colourfulness. LCD colour saturation is not as good as plasma. Blacks are not pure black, and stray back light reduces colour saturation.

Colour Accuracy

Colour accuracy is an extremely complex subject, and impossible to gauge in a store. Absolute color and gray scale accuracy is necessary to display digital photos on your TV. Colour accuracy is intertwined with many other factors, including brightness and viewing angle. Overall, considering colour accuracy combined with viewing angle, plasma is much better.

Connectors

TV connectors have evolved many types. For HDTV the main types are HDMI and USBUniversal serial bus. More is better. Older types that may be found are component video, SWetted surface-video, RF or coaxial cable, and separate audio connectors.

HDMI

A High-Definition Multimedia Interface (HDMI) connection is the go-to connector on a HDTV for high-definition digital video and audio signals. Maximum cable runs are 16 feet (5 meters).

HDMI is compatible with DVI video. You may need an HDMI-to-DVI adapter plug if your source device only has a DVI connector (but you must connect audio separately). HDMI supports High-bandwidth Digital Content Protection (HDCPHigh-bandwidth digital content protection).

USB

A universal serial bus (USB) connector standardizes the connection of keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapter) to personal computers and HDTV, both to communicate and to supply electric power.

An example use is to display digital photos on the TV, or to provide power to a streaming media device such as a Roku stick.

Energy Consumption

A TV consumes around 400 watts (see also ElectricalCapacityAC). Plasma screens consume more energy and they generate a lot of heat because they burn phosphors to display images, requiring cooling fans.