Wireless cable television
by Deepak Bagai
WIRELESS cable TV has come in a big way in the global market for providing cable TV services. A lot of active development has taken place in this area of communication. The name “wireless cable” has emerged from a service known as multichannel multipoint distribution service. Here the satellite channels are transmitted over MMDS frequencies. Wireless cable technology makes use of super high frequency channels to transmit satellite programmes over the air instead of through underground or overhead cables.

Science Quiz
by J. P. Garg

And cars shall fly!
by Manoj Roorkiwal

RIGHT from the day when man came into existence he always dreamt of flying in the air like birds. He tried all sorts of tricks and carried out various experiments to come out with a contraption which could help him fly in open sky. Oliver Wright and Wilbert Wright (Wright brothers) were the first persons in the world to successfully fly in the air on an aeroplane. The success gave wings to the imagination of the people all round the world and people started coming out with various kinds of flying objects. Before the advent of the aeroplane the people flew in balloons. Earlier balloons used to be filled with hydrogen gas. Later on when these started catching fire people started using hot air in balloons. Nowadays hot air balloons are very advanced; they are fitted with a very sophisticated burner, which produces hot air on the flip of a button, whenever required. Today’s balloons are equipped with all sorts of scientific gizmos, which help the pilot to manoeuvre, the balloon very efficiently.

After the balloons another flying object came into existence and it was “the zeppelin”. Zeppelin is a balloon-like structure in the shape of plane, which has cockpit under its belly, in which the passengers can be carried. From this cockpit only the zeppelin can be controlled. The Germans pioneered the art of zeppelin-making and introduced some structural changes like the use of a wooden structure on which the outer surface of the balloon was pasted. During World War I the Germans used the zeppelin very effectively and extensively against their enemies. In the beginning of the war the Germans bombarded the targets effectively, but due to its slow speed the zeppelin was not able to move quickly. So it became the soft target for the enemy guns and after that the future of zeppelin was over.

With time new flying objects made their debut in the aviation history. First came the aeroplane and after a lot of research work the helicopter. The helicopter started a new phase in aviation; from this point onwards the aviation industry never looked back. Now the imagination of the people all over the world went wild and people started thinking of a plane, which can take off vertically almost like a helicopter and move like a plane at a lightning speed. This imagination gave birth to ‘Sea Harrier’ or British Harrier jump jet. Sea Harrier is a versatile plane, which can take off vertically and can work like a plane. It incorporates a thrust deflection vane system that redirects thrust, enabling it to hover or to take off and land vertically from almost any surface. Sea Harrier is the brainchild of the British Aerospace, the pioneer of the finest military and commercial aeroplanes in the world. This plane has two engines, which can move from a horizontal position to a vertical position. In the vertical position the engines make a cushion of air on which it takes off vertically, and once in the air the pilot can change the position of the engines to a horizontal one, which gives a thrust to the plane and it surges ahead at a high speed.

Who can forget the Arnold Shwareznegger and Jamie Lee Curtis starrer ‘True Lies’ in which Shwareznegger takes the US Air Force’s Sea Harrier plane to save his daughter. He did all sorts of stunts with that plane. He made the plane to take off vertically and hover around at a place continuously. He performed such stunts with that plane which can only be performed by a helicopter. This is the versatility of a Sea Harrier.

India also has a large fleet of Sea Harrier planes. Earlier, this fleet was stationed on the Indian Naval Ship Vikrant. Now Vikrant is decommissioned and this fleet is stationed on INS Viraat. Harrier jump jet is a very small combat craft whose wings can be folded. It requires very small space in the hangar.

At present there is a big boom in the Indian car industry. Every car manufacturer is launching one car or the other. There is Santro, Matiz, Indica in the small car segment and Hyundai LC, Fiat Sienna, Mitsubishi Lancer and an improved version of Opel Astra in the luxury sedan segment. Then there are Honda and Mercedes too. The advent of new and sophisticated cars has brought the price war also. Now car is no more a luxury item but a necessity.

Availability of cars at a cheaper price has given rise to choked roads and traffic jams. This situation has given rise to frustration in motorists and people now want a car which can fly and avoid all sorts of traffic hurdles like red lights, speed humps. This frustration in a way has guided the US engineer Paul Moller and his company Moller International to come out with a car, which will hover above the ground and could change the way people travel in the future. Can one imagine to reach point A to Point B in a fraction of the time and that too with no red lights, no traffic, and no hassle?

Paul Moller’s company, Moller International (California) has made a sky car which is Batmobile shaped, can seat four persons, do about five miles per litre of gas, has a top speed of over 600 mph and can take off vertically. Initially the sky car can rise to a height of six feet and is easily manoeuvrable in the air. It can hover and land like a Harrier jump jet.

Revolutionary ideas are not born overnight. Moller has been working on this project for the last 30 years. The concept of Sea Harrier has paved the way for the “Flying car M 400”. The car is hand made and can cost about $ 1 million. This car has yet to receive a licence from the Federal Aviation Administration (FAA).

It uses rotapower engines and fans placed inside streamlined housings known as nacelles. The engines provide a high power to weight ratio at a reasonable cost and are very small for their power output. The 150 HP model rotapower engines used in the M400 sky car can be easily carried by one person. The fans inside the nacelles create an airflow that generates thrust. Each car will have a total of four nacelles to provide the power. At the rear of each nacelle is a set of vanes that can be angled downwards to generate lift as well as forward thrust.

Paul Moller had said that “the first sky cars will be fly-by-wire vehicles”. The pilot will only tell the craft what to do and the computer will actually do the flying, taking the vehicle’s rate of turn and altitude into account when it responds to instructions.

The M400 sky car (4-seat) production prototype is ready and is expected to fly within a few months. Its predecessor the M200X (2-seat), has made over 200 flights and had flown to a height of 40 feet.

The sky car M400 is perfectly safe as it has eight engines so that if one or more fail, it can still operate safely. It has three independent computers for flight management with only one needed to fly. It also has two backup airframe parachutes.

Actually a computer does the flying. The pilot has to only move the controls in the direction he wants to go so that little skill is required. Though it is easy to fly, the operator will need to have a private pilot’s licence until the ease of operation and safety are thoroughly demonstrated.

The sky car is made up of a composite airframe constructed mostly of FRP (Fibre reinforced plastic), while the engines are mostly aluminium. It will be available in a very limited numbers during the next 18 months.

The rotapower engines of M 400 sky car are multi-fuel capable. Though engines are typically configured to run on unleaded gasoline, but with a little modification they can run on diesel and natural gas also. These rotapower engines are not intended for use in automotive applications.

The sky car is user friendly — its all-rotating components are mounted within the nacelles to prevent human contact. Artificial stabilisation ensures that the normally more difficult take off and landing flight phase is routine.

Energy absorption techniques and materials will be used in the structure wherever possible to minimise the consequences of an accident. The low speed parachute will provide protection from almost any height provided that the sky car has some forward speed to accelerate the chute’s fill rate. One air bag will be used extensively within the sky car as well as at critical places on the exterior.

In 1992, Moller International received the only generic patent ever issued in the US on an entirely new aircraft. This unique design is also the only aircraft at present considered by the FAA (Federal Aviation Administration) for certification and the new “Powered Lift-Normal” category.

The sky car has the capability of averaging 300 MPH from take off to landing, which could reduce travel time to 40 hours per year for the average user.

A flying car is not a new idea but all the earlier flying cars were just conventional vehicles with wings bolted on top. Their wings had to be dismantled before the vehicle could run on roads.

Moller says “This is the first and only feasible, personally affordable, personal vertical take off and landing (VTOL) vehicle the world has ever seen”.

Though the car’s test flights are success but it would have to take off from what Moller calls a vertiport. Safety risks and deafening noise levels make it impractical to take off in the middle of the street but he believes that with minor futuristic modifications in the sky car the vertiports could be as common as corner shops.

Paul Moller says: No matter how you look at it, the automobile is only an interim step on our evolutionary path to independence from gravity. That’s all it will ever be.”

The sky car will be limited production (500 units per year) and it will sell for a price comparable to that of four-passenger high performance helicopter or airplane (approximately $ 1 million). As the volume of production increases substantially, its price can approach that of a luxury automobile.

Sixty years ago the founder for Ford Motors, Henry Ford predicted that one day a hybrid vehicle which will be a cross between an aeroplane and a car will rule the sky. His prediction was very true and Moller’s sky car is the first step towards that direction.

Wireless cable television
by Deepak Bagai

WIRELESS cable TV (WCTV) has come in a big way in the global market for providing cable TV services. A lot of active development has taken place in this area of communication. The name “wireless cable” has emerged from a service known as multichannel multipoint distribution service (MMDS). Here the satellite channels are transmitted over MMDS frequencies. Wireless cable technology makes use of super high frequency (SHF) channels to transmit satellite programmes over the air instead of through underground or overhead cables.

The household subscribing to the wireless cable TV service shall require a small antenna on the rooftop. In addition a down converter, including an addressable decoder and built in VHF/UHF tuner, will be needed. This facility will give the ability to tune on to broadcast channels without using MMDS channels. This also facilitates pay-per-view services, simplified channel blocking and premium channel activation/deactivation. A new converter is being introduced that will send all the channels out of the converter at once.

The optimum range for wireless cable systems is about 48 km. The range is dependent on the terrain, transmitting power, transmitting and the receiving equipment and many other factors. The transmitting and the receiving antenna have to be in the line of site. A range of about 150 km would be possible by using the concept of digital compression. The signal security is accomplished by encoding each channel and equipping the converter with a decoding device thereby making the system fully addressable. This further helps in enabling the concept of pay-per-view service.

Multichannel multipoint distribution service (MMDS) is an extension of multipoint distribution service (MDS) which could transmit only one or two channels. MMDS generally has two sets of four channels each. This type of service is known as “wireless cable”. An MMDS licensee leases transmission time to programmers. They, in turn, sell their programmes to the subscriber. The tests are being done in the 28 GHz band.

Wireless cable can have as many as 33 channels of broadcast and cable programming. This can go upto about 150 channels by using digital compression. With digital transmission the range will also increase by almost three times.

This service can be made available to a scattered population and locations where it is expensive to build a traditional cable network. The savings so obtained can be passed on to the consumer thus making it affordable for the masses. Since the signal is transmitted over the air, it is not prone to the failure of cable. Furthermore the antennas are very similar to ordinary television antennas. Thus it has been proven beyond doubt that an efficient, flexible, reliable, safe and cost-effective wireless cable technology is the need of the day.

Science Quiz
by J. P. Garg

1. The German chemist Christian Friedrich Schonbein accidentally spilled some nitric acid while performing an experiment in his wife’s kitchen. He cleaned the acid with a cotton apron lying there. When he tried to dry the apron over the stove, it vanished with a smokeless bang. What had he discovered?

2. With the showing of World Cup on the silver screen by a theatre in Jaipur, the concept of electronic cinema has arrived in India. Which technology will soon replace the age-old celluloid film technology for projection which will be capable of one lakh screening as compared to about 100 of a celluloid film?

3. Acid rainfall causes serious pollution, soil erosion and may even damage buildings. Which main pollutants are there in acid rain and how are they produced?

4. Located deep inside the brain, this internal timer of the size of a pea regulates the production of hormones and provides signals to the body such as when to sleep, wakeup, work, play or even mate. What is this part of the brain called?

5. Excessive intake of chillies can not only be harmful but sometimes dangerous also. Which chemical is there in chillies that is pungent and to some extend poisonous?

6. To clear blockade in the coronary artery, doctors insert a tiny balloon into the artery and then inflate the balloon to clear the blockade. What is this technique called?

7. When the sand is extremely hot, shovel-snouted desert lizard lifts opposite pairs of is feet alternately so that they can cool in the air. What is this behaviour of the lizard called?

8. Animals like frogs and toads that live on land and in water are called amphibians, which plant group shows similar characteristics?

9. The British scientist Sir Isaac Newton is known for his wide ranging work in physics. To which branch of mathematics did Newton make a pioneering contribution?

10. ICRISAT is an institute in Andhra Pradesh engaged in modern agricultural research and training. What is the full name of this institute?

ANSWERS

1. Gun cotton (cellulose nitrate) 2. DVD (Digital Versatile Disc) 3. Suphur dioxide, oxides of carbon, hydrocarbons etc.; by burning of fossil fuels 4. Pineal gland 5.Capsaicin 6. Angiography 7. Thermal dancing 8. Bryophytes . Calculus 10. International Crops Research Institute for the semi-Arid Tropics.

GPS on your wrist
WITH Casio’s GPS, checking your location is as easy as glancing at your wrist. The watch displays the longitude and latitude of your current position, or the direction and distance to a present location. The 5.2-ounce watch measures 2.6 by 2.6 by 1.1 inches and is 60 per cent the size and weight of conventional hand-held units, says the company. The price is not yet set. (Popular Science)

Army guns to be fired virtually
British soldiers are using a virtual reality simulator for their training in tank warfare with sophisticated computers and software incorporated in the system.

The system would enable troops to carry out reconnaissance training without the environmental and cost implications usually associated with live artillery firing.

Called warrior observation post vehicle trainer (OPVT), the system comprises three simulators and a command module for an instructor.

It is being used to train tank crews who usually scout ahead of a military force to locate targets for long-range attack by artillery units.

Designed to duplicate the inside of a warrior tank, the OPVT incorporates all the communication equipment, artillery systems, thermal imaging for night vision and target acquisition radar found inside a vehicle, reports London Press Service.

Fire-retardant polymer
A new fire-retardant polymer, which releases water vapour when it catches fire, can be used in aircraft to reduce deaths in air crashes.

Forty per cent of people who survive an air crash ultimately die in the ensuing fire and toxic fumes from the burning polymers as the interior in most of the large commercial aircraft is built of combustible plastics.

The new polymer, called polyhydroxyamide (PHA), developed by researchers of University of Massachussets in Boston, decomposes into a rigid flame-resistant substance called polybenzoxazole (PBO).

While doing so, it releases water vapour into the atmosphere to help suppress a fire, reports New Scientist.

Carpets, overhead lockers, partitions and seat covers in aircraft are made of inflammable materials which release flammable gases and toxic fumes during a fire. The new polymer can act as a better substitute to these materials.

Robot repairers in sight
Researchers in Loughborough University in England are working on a system that can overcome many of the problems involved in using mobile robots in hazardous work areas like nuclear power stations.

Called “teleman”, the system can also be used for disposal of bombs and mines.

The system does not use radio links that are subject to interference or heavy cables which may become snagged or broken.

Instead, it uses laser and infrared (IR) links to remotely control a robot vehicle in hazardous environments where cable or radio communication is not feasible due to interference problems.

It uses appropriately-stationed relay robots to communicate around obstacles, reports London Press Service.

The communication link is designed by using a closed-circuit television (CCTV) camera tracking a laser point generated by the fibre optic network of the system.

When the tracking camera has this point in the centre of its picture, twin-receivers are mutually aligned with corresponding IR transmitters on the opposite unit.

The IR signal is then modulated to transmit commands between the units or to feed CCTV pictures or send the data back to the base station.