Power and Antenna subsystem in satellite communication

Power Systems

We know that the satellite present in an orbit should be operated continuously during its life span. So, the satellite requires internal power in order to operate various electronic systems and communications payload that are present in it.

Power system is a vital subsystem, which provides the power required for working of a satellite. Mainly, the solar cells (or panels) and rechargeable batteries are used in these systems.

Solar Cells

Basically, the solar cells produce electrical power (current) from incident sunlight. Therefore, solar cells are used primarily in order to provide power to other subsystems of satellite.

We know that individual solar cells generate very less power. So, in order to generate more power, group of cells that are present in an array form can be used.

Solar Arrays

There are two types of solar arrays that are used in satellites. Those are cylindrical solar arrays and rectangular solar arrays or solar sail.

• Cylindrical solar arrays are used in spinning satellites. Only part of the cylindrical array will be covered under sunshine at any given time. Due to this, electric power gets generated from the partial solar array. This is the drawback of this type.
• The drawback of cylindrical solar arrays is overcome with Solar sail. This one produce more power because all solar cells of solar sail are exposed to sun light.

Rechargeable Batteries

During eclipses time, it is difficult to get the power from sun light. So, in that situation the other subsystems get the power from rechargeable batteries. These batteries produce power to other subsystems during launching of satellite also.

In general, these batteries charge due to excess current, which is generated by solar cells in the presence of sun light.

Antenna Subsystems

Antennas are present in both satellite and earth station. Now, let us discuss about the satellite antennas.

Satellite antennas perform two types of functions. Those are receiving of signals, which are coming from earth station and transmitting signals to one or more earth stations based on the requirement. In other words, the satellite antennas receive uplink signals and transmit downlink signals.

We know that the length of satellite antennas is inversely proportional to the operating frequency. The operating frequency has to be increased in order to reduce the length of satellite antennas. Therefore, satellite antennas operate in the order of GHz frequencies.

Satellite Antennas

The antennas, which are used in satellite are known as satellite antennas. There are mainly four types of Antennas. They are:

• Wire Antennas
• Horn Antennas
• Array Antennas
• Reflector Antennas

Now, let us discuss about these antennas one by one.

Wire Antennas

Wire antennas are the basic antennas. Mono pole and dipole antennas come under this category. These are used in very high frequencies in order to provide the communication for TTCM subsystem.

The length of the total wire, which is being used as a dipole, if equals half of the wave length (i.e., l = λ/2), such an antenna is called as half-wave dipole antenna.

Wire antennas are suitable for covering its range of access and to provide signal strength in all directions. That means, wire antennas are Omni-directional antennas.

Horn Antennas

An Antenna with an aperture at the end can be termed as an Aperture antenna. The edge of a transmission line when terminated with an opening, radiates energy. This opening which is an aperture, makes it as an aperture antenna.

Horn antenna is an example of aperture antenna. It is used in satellites in order to cover more area on earth.

Horn antennas are used in microwave frequency range. The same feed horn can be used for both transmitting and receiving the signals. A device named duplexer, which separates these two signals.

Array Antennas

An antenna when individually can radiate an amount of energy, in a particular direction, resulting in better transmission, how it would be if few more elements are added it, to produce more efficient output. It is exactly this idea, which lead to the invention of Array Antennas or Antenna arrays. Array antennas are used in satellites to form multiple beams from single aperture.

Reflector Antennas

Reflector antennas are suitable for producing beams, which have more signal strength in one particular direction. That means, these are highly directional antennas. So, Parabolic reflectors increase the gain of antennas in satellite communication system. Hence, these are used in telecommunications and broadcasting.

If a Parabolic Reflector antenna is used for transmitting a signal, the signal from the feed, comes out of a dipole or a horn antenna, to focus the wave on to the parabola. It means that, the waves come out of the focal point and strikes the Paraboloidal reflector. This wave now gets reflected as collimated wave front.

If the same antenna is used as a receiver, the electromagnetic wave when hits the shape of the parabola, the wave gets reflected onto the feed point. The dipole or the horn antenna, which acts as the receiver antenna at its feed, receives this signal, to convert it into electric signal and forwards it to the receiver circuitry.

Fire Safety And Pollution Control While Cooking

Cooking releases several pollutants as well as particulate matter into the air.

Deepshikha Shukla

When such pollutants are exhausted from a kitchen, these can release smoke, grease and odours in outdoor air. Exposure to contaminated air may lead to such health problems as asthma, cough and respiratory tract infections.

Most victims of fires die due to inhalation of smoke or toxic gases rather than burns. Cooking is the primary cause of home fires. Smart sensors, powerful chimneys, smoke detectors and alarms can be added to the kitchen for safety purposes. Keeping a fire extinguisher near the kitchen for the worst cases and learning how to use it can come in handy in case of emergencies.

The Internet of Things (IoT) is making possible a new wave of smart kitchen gadgets, from sensors that maintain a favourable temperature to those that keep track of activities on the stove. Here is a roundup of safety devices for your kitchen.

Smoke detectors

A smoke detector keeps an eye on things and can send alerts about a problem at home to users anywhere in the networked world. It can be used anywhere in the house, but is especially useful in the kitchen, where it can check for gas buildup from a leaky or forgotten stove.

A smoke detector, like Birdi, monitors smoke, carbon-monoxide, pollen, particulates, temperature and humidity. If any of these rise to worrisome levels, it alerts the users and anyone else who is authorised (friends, family or neighbours) via text message, or an automated call to the cellphone or landline. This way users know something is wrong even when they are not at home to hear the alarm.

Multiple devices can also repeat alarms from other rooms or even other houses if the neighbours connect their device to the users’.

Some smart fire alarm devices like Nest Protect also follow voice commands.

There are two types of smoke detectors, namely, battery-powered ones and those that can be connected to the main electric supply. Some can also be integrated with other smart home devices. The best ones, however, are the dual sensor alarms, which are a combination of ionisation and photoelectric technology.

Chimneys

For a smoke-free and healthy cooking experience, there are various chimneys available in the market in variable sizes and power. These provide control at one touch, or motion of the hand, with the help of touch and motion sensors. Motion sensor feature enables chimneys to be switched on with just a wave of the hand.

A heat sensor enables the chimney to start automatically when cooking starts. An LPG sensor switches on the chimney if there is any leakage in the kitchen and throws all the gas out of the kitchen. A motor with thermal overload protector ensures that, in case of overheating, the motor does not burn out. Suction power of the chimney leads to the removal of combustion products, odour, fumes, steam, smoke, heat and grease that develop during cooking.

Auto clean feature cleans the oil and residue collected in the chimney automatically. This makes their working and maintenance easier. Size and power of the chimney depend on the size of the kitchen, the kind of cooking and how often cooking is done in a day.

Three chimneys with the desired features are:

• Glen Auto Clean Chimney 6063 SS. Has 90cm width, 230W motor, 1200m3/hr suction power, baffle filters, touch sensor, heat auto-clean function with noise level less than 58dB

• Hindware Alicia Plus. Has 90cm width, auto-clean chimney, 1200m3/ hr suction power, touch control with motion sensor, double-layer SS filter, noise level less than 58dB, 215W motor

• Faber Primus Energy. Has 90cm width, 1500m3/hr suction power, baffle filter, thermal auto-clean, metal blower, touch control, noise 58dB, 250W motor power

Remote control feature allows users to operate the chimney remotely if they are caught up with other tasks. 2D filter technology has two filters placed in two directions, horizontally and vertically, which, when combined, filter the air comprehensively. The filters ensure that every particle, oil and residue is trapped effectively for a smoke-free clean kitchen. The metal blower eliminates the task of replacement of filters at regular intervals.

A timer-enabled chimney helps in effortlessly managing cooking time by auto-setting the duration of various functions. The timer automatically switches off the chimney after the set time. A chimney with a powerful motor having high suction capacity, longer operational life, less power consumption and less noise works wonders.

Smart sensors for safe cooking Safera Sense.

It allows you to connect the stove to a smart home ecosystem. It can immediately recognise the temperature if it rises to a dangerously high level. If this happens, the device will send an alarm signal and automatically shut down the power supply before the oil bursts into flames. This device has over ten sensors to measure stove temperature, activities and air quality.

Inside the device, a processor continuously analyses the data to monitor possible events. In addition, all recorded data is sent to the mobile device. The device monitors stove temperature, power consumption and human presence. It prevents cooking fires by triggering the alarm and, if necessary, turning off the stove.

The connected Safera app gives live diagnostics of house temperature, humidity and air quality. In turn, it notifies the users as to when to increase stove ventilation, or even open a window. The second the users start cooking, it creates a cooking timeline in Safera app. It recognises various cooking events and sets up automatic timers for each of them. For example, if the users do not remember how long they have been cooking the pasta, they can simply check the app and scroll back to past events. It enables them to control the stove using voice commands. It is designed to measure a variety of air quality levels, including air quality index, temperature, humidity and 

Daily updates 9 October 2019

           National

1. AIIMS & Health ministry launches "eDantSeva"

• The All India Institute of Medical Sciences in collaboration with the Union Health Ministry launched the 1st-ever website and mobile application on oral health awareness "eDantSeva".
• The digital platform contains information about the National Oral Health Programme and a detailed list of all the dental facility and colleges, Information, Education and Communication (IEC) material.
• It also constitutes a unique feature called the 'Symptom Checker'. The website also provides GPRS route and satellite images of the facility for easier access to the people.
• A Braille booklet and voice-over on oral health education for visually impaired was also released on the occasion.

2. CBDT launches Faceless e-Assessment scheme

• The Central Board of Direct Taxes has launched "Faceless e-Assessment scheme" that eliminates physical interface between an assessing officer and an assessee. They also inaugurated the National e-Assessment Centre (NeAC).
• The "Faceless e-assessment scheme" is expected to bring in a “paradigm shift” in taxation by eliminating human interface in the income tax assessment system.
• A total of 2,686 officials of the I-T department have been deputed for implementation of the scheme. With NeAC, there would be no physical interface between the tax payers and the tax officers.
• Also, the above will bring transparency and efficiency and will improve the quality of assessment and monitoring.
• There would be a NeAC in Delhi to be headed by Principal Chief Commissioner of Income Tax.
• There are 8 Regional e-Assessment Centres (ReAC) set up at Delhi, Mumbai, Chennai, Kolkata Ahmedabad, Pune, Bengaluru and Hyderabad which would comprise Assessment unit, Review unit, Technical unit and Verification units.

Static/Current Takeaways Important For IBPS RRB Clerk Mains:

• Chairman of CBDT: P.C. Mody.

3. India receives 1st Rafale fighter jet built for Indian Air Force

• India has got the 1st Rafale fighter jet "RB-001" built for the Indian Air Force (IAF) in France. Defence Minister Rajnath Singh received the 1st Rafale combat jet aircraft at Production Unit of Dassault Aviation in France.
• However, the first batch of jets will arrive in India only in May 2020. Defence Minister also held the Annual Defence dialogue with his French counterpart Florence Parly.
• The RB in the aircraft designation stands for IAF Chief Air Chief Marshal R.K.S. Bhadauria who as then Deputy Chief of IAF led the Indian negotiation team and had a major role in the contract negotiations.

4. Air Force Day: 8th october

• Air Force Day is celebrated every year by the Indian Air Force on 8th of October. This year Indian Air Force celebrated its 87th anniversary. The IAF was founded on October 8, 1932.
• On the occasion of 87th anniversary of Indian Air Force, a scintillating air display by various aircraft was organized as the hallmark of the Air Force Day Parade-cum-Investiture Ceremony.
• The display commenced with flag bearing skydivers of the famous AKASH GANGA Team dropping out of an AN-32 aircraft in their colourful canopies.
• Indian Air Force officers who participated in the Balakot airstrike, flew three Mirage 2000 aircraft and two Su-30 MKI fighter aircraft in Avenger formation during the event.

Static/Current Takeaways Important For IBPS RRB Main 2019:

• Air Force Chief: Rakesh Kumar Singh Bhadauria.

International News

5. Antonio Costa re-elected as the PM of Portugal

• Antonio Costa has been re-elected as the Prime Minister of Portugal after winning the general elections.
• Antonio Costa, the Socialist leader and incumbent prime minister, got the most votes in Portugal’s general election, leaving it poised to continue leading the government for another four years.

Awards

6. The Nobel Prize in Physiology or Medicine 2019

• The Nobel Assembly has announced the 2019 Nobel Prize in Physiology or Medicine at Karolinska Institutet.
• The prize will be awarded jointly to William G. Kaelin, Sir Peter J. Ratcliffe and Gregg L. Semenza. They have been nominated for the prize for their discoveries of how cells sense and adapt to oxygen availability.
• The prize committees are currently working carefully and independently to select the recipients of the 2019 Nobel Prize and the laureates for other fields: Physics, Chemistry, Literature, Peace Prize and the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel.
• The recipient for above prizes will be announced as per the schedule between 8th to 14th October, 2019.

7. The Nobel Prize in Physics 2019

• The Nobel Assembly has announced the 2019 Nobel Prize in Physics. The prize will be awarded to James Peebles, Michel Mayor and Didier Queloz.
• James Peebles was honoured for his contributions to the understanding of the evolution of the Universe and Earth's place in the cosmos. Michel Mayor and Didier Queloz were awarded the prize for finding 51 Pegasi b, a gas giant orbiting a star 50 light-years away.
• It was the first exoplanet to be discovered orbiting a star like our own.

8. "Spirit Of Kerala" wins People's Choice Award

• Short film from Kerala "Spirit Of Kerala" has won the People's Choice Award at the recently concluded My Rode Reel film competition.
• The film won the honour beating 1,680 entries. The short film is based on a boat race and directed by Arun Joseph.
• My Rode Reel film competition is touted as the ‘world’s largest short film competition’.

9. The Nobel Prize in Chemistry 2019

• The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry 2019.
• The prize will be awarded jointly to John B. Goodenough, M. Stanley Whittingham and Akira Yoshino. They have been nominated for the prize for the development of lithium-ion batteries.
• This lightweight, rechargeable and powerful battery is now used in everything from mobile phones to laptops and electric vehicles.

Business News

10. Reliance MF renamed as "Nippon India Mutual Fund"

• Reliance Mutual Fund has been renamed as "Nippon India Mutual Fund". The organization was renamed following the purchase of 75% stake in Reliance Nippon Life Asset Management by Nippon Life Insurance.
• Nippon India Mutual Fund has become the largest foreign-owned Asset Management Company in India. Sundeep Sikka will continue to lead company as the CEO.

11. Infosys bags digital transformation services deal from Volvo

• Infosys has been selected as the main supplier to deliver Volvo Cars’ digital transformation services for its enterprise digital commercial operations applications and products.
• Infosys will offer next generation application services leveraging its global delivery model (GDM), agile delivery, automation and other service optimisation levers to deliver effective service operations.
• Based on the Scale Agile Framework (SAFe), Infosys will enable transformation of application management and application development deliveries to a 100% agile operating model.

Ranks and Reports

12. India ranks 68th on WEF's Global Competitiveness Index

• World Economic Forum has released the Global Competitiveness Index report. In total, there are 103 indicators distributed across the 12 pillars on which the performance of the countries was evaluated.
• As per the WEF's released report, India has moved down 10 places to rank 68th on an annual global competitiveness index which was topped by Singapore.
• India is among the worst-performing BRICS nations along with Brazil which is ranked 71st this year.
• WEF stated that India ranks high in terms of macroeconomic stability and market size, while its financial sector is relatively deep and stable despite the high delinquency rate, which contributes to weakening the soundness of its banking system.
• Here is the detailed ranking of India in individual pillars across which the performance of the countries was evaluated:

Sl. No.	Pillars	Rank
1.	Institutions	59
2.	Infrastructure	70
3.	ICT Adoption	120
4.	Macroeconomic Stability	43
5.	Health	110
6.	Skills	107
7.	Product Market	101
8.	Labour Market	103
9.	Financial System	40
10.	Market Size	3
11.	Business Dynamism	69
12.	Innovation Capability	35

Important Days

13. World Habitat Day: 7 October

• The United Nations designated the first Monday of October of every year as World Habitat Day. The Day is observed to remind the world that we all have the power and the responsibility to shape the future of our cities and towns.
• The focus of this year’s World Habitat Day is promoting the contribution of innovative frontier technologies to sustainable waste management to achieve Sustainable Development Goal 11: inclusive, safe, resilient and sustainable cities.
• Theme for 2019: Frontier Technologies as an innovative tool to transform waste to wealth.
• This year’s Global Observance of World Habitat Day will be held in Mexico City.

Static/Current Takeaways Important For IBPS RRB Clerk Mains:

• Headquarters of United Nations: New York, USA; Founded: 24 October 1945.
• Secretary General of the United Nations: Antonio Guterres.

14. World Post Day: 9 October

• United Nations celebrates World Post Day every year on 9 October. The purpose of World Post Day is to bring awareness to the Post’s role in the everyday lives of people and businesses, as well as its contribution to global social and economic development.
• The Posts in many countries use the event to introduce or promote new postal products and services.
• The day marks the establishment of the Universal Postal Union in 1874 in the Swiss Capital, Bern. It was declared World Post Day by the UPU Congress held in Tokyo, Japan in 1969.

Sports

15. Simone Biles wins 15th world title

• Simone Biles has clinched a record-extending 15th World Gymnastics Championship title in Stuttgart, Germany. With the victory, she has become the event's most decorated woman.
• Simone Biles won a record 21st medal at the world gymnastics championships as the United States retained their women's team all-around title.
• Biles played a key role in a commanding performance by the USA, earning the most points in three of the four disciplines: the vault, balance beam and floor.

Miscellaneous

16. Day Care Recreation Centre inaugurated in Leh

• The 1st Government-sponsored and operated Day-Care cum Recreation Centre for senior citizens has been inaugurated in Leh.
• The day care Centre, co-sponsored by Government and the District Legal Service Authority will provide a raft of medical facilities including geriatric care, health consultations and check-ups, physiotherapy to the senior citizens. It would also provide legal service, the senior citizens would require on various legal issues.
• The premise would be a one stop-shop for entertainment, medical services and legal aid for the aged people of the Ladakh region.