Remote Sensing System

Elements of EMR

In the context of remote sensing, an EMR (electromagnetic radiation) system is a device that is used to detect and measure electromagnetic radiation emitted by objects or substances in the environment. EMR systems can operate over a wide range of frequencies, from radio waves to gamma rays, and can be used for a variety of applications, including mapping the Earth’s surface, studying the atmosphere, and monitoring the health of crops.

There are several key elements that make up an EMR system used in remote sensing:

1. Antenna: An antenna is used to collect electromagnetic radiation emitted by objects or substances in the environment and transmit it to the receiver. The type of antenna used in an EMR system depends on the frequency range of the radiation being measured.
2. Receiver: The receiver is responsible for converting the collected electromagnetic radiation into a form that can be processed and analyzed by the system. This typically involves amplifying the signal and demodulating it to extract the information contained within it.
3. Processor: The processor is responsible for processing the received electromagnetic radiation and extracting useful information from it. This may involve applying algorithms to the data to extract features or patterns, or creating maps or images based on the data.
4. Storage and display: The processed data must be stored somewhere, typically in a computer or other device, so that it can be accessed and analyzed later. The data may also be displayed on a screen or other output device, such as a printer or plotter, to allow the user to view and interpret the results.

Wavelength Region

In the context of remote sensing, the wavelength region refers to the range of wavelengths of electromagnetic radiation that can be detected and measured by the system. Different remote sensing systems are designed to operate over different wavelength ranges, depending on the specific application and the type of information being sought.
Some common wavelength regions used in remote sensing include:

1. Visible light: This wavelength region is the portion of the electromagnetic spectrum that is visible to the human eye and ranges from about 400 to 700 nanometers (nm).
2. Near-infrared (NIR): This wavelength region is just beyond the visible spectrum and ranges from about 700 to 2500 nm. NIR radiation is often used to study vegetation and soil moisture content.
3. Shortwave infrared (SWIR): This wavelength region ranges from about 1.4 to 3 micrometers (μm) and is often used to study minerals and water content in soil and vegetation.
4. Thermal infrared (TIR): This wavelength region ranges from about 8 to 14 μm and is used to measure the temperature of objects and surfaces.
5. Microwave: This wavelength region ranges from about 1 mm to 1 m and is used to study the Earth’s surface and atmosphere, as well as to detect water and other subsurface features.

Each of these wavelength regions has its own unique characteristics and is suited to different types of applications in remote sensing.

Energy Interaction in Atmosphere

In the context of remote sensing, the energy interaction of electromagnetic radiation (EMR) with the atmosphere refers to the way in which EMR is absorbed, scattered, or reflected by the various gases, particles, and other substances that make up the Earth’s atmosphere. These interactions play a key role in determining the characteristics of the EMR that is detected by remote sensing systems and are an important factor to consider when interpreting remote sensing data.

There are several types of energy interactions that can occur in the atmosphere, including:

1. Absorption: This occurs when EMR is absorbed by the gases or particles in the atmosphere, reducing the amount of radiation that reaches the Earth’s surface. Absorption is most pronounced in the ultraviolet and infrared regions of the electromagnetic spectrum.
2. Scattering: This occurs when EMR is scattered by particles or gases in the atmosphere, causing it to change direction and become more diffuse. Scattering is most pronounced in the visible and near-infrared regions of the spectrum and can lead to hazy or cloudy conditions.
3. Reflection: This occurs when EMR is reflected by the Earth’s surface or atmospheric particles and returns to the atmosphere. Reflection is most pronounced in the visible and near-infrared regions of the spectrum and is an important factor in the albedo, or reflectivity, of the Earth’s surface.

Understanding the energy interactions that occur in the atmosphere is important in the field of remote sensing because it can help scientists and researchers to interpret the data collected by remote sensing systems and understand the characteristics of the objects and substances being studied.

Absorption

In the context of remote sensing, absorption refers to the process by which electromagnetic radiation (EMR) is absorbed by the gases or particles in the atmosphere, reducing the amount of radiation that reaches the Earth’s surface. Absorption is most pronounced in the ultraviolet and infrared regions of the electromagnetic spectrum and is caused by the interaction of EMR with the molecules or atoms of the absorbing substance.
Absorption can have a significant impact on the characteristics of the EMR detected by remote sensing systems, and it is an important factor to consider when interpreting remote sensing data. For example, absorption in the ultraviolet and infrared regions of the spectrum can be used to study the composition and temperature of the Earth’s atmosphere, as well as to detect the presence of certain gases or substances.
In addition to its role in the atmosphere, absorption is also an important factor in the interaction of EMR with the Earth’s surface and the objects and substances on it. Different materials and substances absorb EMR to different degrees, depending on their chemical composition and physical properties, and this can be used to study and identify these materials using remote sensing techniques.

Scattering

In the context of remote sensing, scattering refers to the process by which electromagnetic radiation (EMR) is scattered, or deflected, by particles or gases in the atmosphere, causing it to change direction and become more diffuse. Scattering is most pronounced in the visible and near-infrared regions of the electromagnetic spectrum and is caused by the interaction of EMR with the molecules or atoms of the scattering substance.
There are several types of scattering that can occur in the atmosphere, including:

1. Elastic scattering: This occurs when the EMR is scattered by particles or gases in the atmosphere, but the frequency and wavelength of the radiation remain unchanged.
2. Inelastic scattering: This occurs when the EMR is scattered by particles or gases in the atmosphere, but the frequency and wavelength of the radiation are changed.

Scattering can have a significant impact on the characteristics of the EMR detected by remote sensing systems, and it is an important factor to consider when interpreting remote sensing data. For example, scattering can cause the EMR to become more diffuse, leading to hazy or cloudy conditions, or it can cause the EMR to be scattered in different directions, leading to shadows or other visible effects.
In addition to its role in the atmosphere, scattering is also an important factor in the interaction of EMR with the Earth’s surface and the objects and substances on it. Different materials and substances scatter EMR to different degrees, depending on their chemical composition and physical properties, and this can be used to study and identify these materials using remote sensing techniques.

Atmospheric Window

In the context of remote sensing, the atmospheric window refers to the portion of the electromagnetic spectrum that is least absorbed by the Earth’s atmosphere and is therefore most suitable for remote sensing applications. The atmospheric window is characterized by relatively low levels of absorption and scattering, which allows the EMR to pass through the atmosphere with minimal loss or distortion, making it easier to detect and measure from space.
There are several atmospheric windows that are commonly used in remote sensing, including:

1. Visible light: This wavelength region is the portion of the electromagnetic spectrum that is visible to the human eye and ranges from about 400 to 700 nanometers (nm). The visible light window is the most widely used atmospheric window in remote sensing and is used to study the Earth’s surface, vegetation, and other features.
2. Near-infrared (NIR): This wavelength region is just beyond the visible spectrum and ranges from about 700 to 2500 nm. The NIR window is used to study vegetation and soil moisture content, as well as to detect the presence of certain minerals.
3. Shortwave infrared (SWIR): This wavelength region ranges from about 1.4 to 3 micrometers (μm) and is used to study minerals and water content in soil and vegetation.
4. Thermal infrared (TIR): This wavelength region ranges from about 8 to 14 μm and is used to measure the temperature of objects and surfaces.

Each of these atmospheric windows has its own unique characteristics and is suited to different types of applications in remote sensing. By selecting the appropriate atmospheric window for a given application, scientists and researchers can maximize the amount of useful information that can be obtained from remote sensing data.

Terrestrial Interaction

In the context of remote sensing, terrestrial interaction refers to the way in which electromagnetic radiation (EMR) interacts with the Earth’s surface and the objects and substances on it. These interactions play a key role in determining the characteristics of the EMR that is detected by remote sensing systems and are an important factor to consider when interpreting remote sensing data.
There are several types of terrestrial interaction that can occur, including:

1. Absorption: This occurs when EMR is absorbed by the materials and substances on the Earth’s surface, reducing the amount of radiation that is reflected back into the atmosphere. Absorption is most pronounced in the ultraviolet and infrared regions of the electromagnetic spectrum and is dependent on the chemical composition and physical properties of the absorbing substance.
2. Scattering: This occurs when EMR is scattered, or deflected, by the materials and substances on the Earth’s surface, causing it to change direction and become more diffuse. Scattering is most pronounced in the visible and near-infrared regions of the spectrum and is dependent on the chemical composition and physical properties of the scattering substance.
3. Reflection: This occurs when EMR is reflected by the Earth’s surface and returns to the atmosphere. Reflection is most pronounced in the visible and near-infrared regions of the spectrum and is an important factor in the albedo, or reflectivity, of the Earth’s surface.

Understanding the terrestrial interaction of EMR is important in the field of remote sensing because it can help scientists and researchers to interpret the data collected by remote sensing systems and understand the characteristics of the objects and substances being studied.

Spectral Reflectance Curve

In the context of remote sensing, a spectral reflectance curve is a graph that shows the percentage of electromagnetic radiation (EMR) that is reflected by an object or substance as a function of wavelength. Spectral reflectance curves are used to study the reflectance properties of materials and substances on the Earth’s surface and are an important tool in the interpretation of remote sensing data.
Spectral reflectance curves are typically plotted on a graph with wavelength on the x-axis and reflectance on the y-axis. The shape of the curve is determined by the chemical composition and physical properties of the object or substance being studied, and can be used to identify and classify different materials and substances.
For example, a spectral reflectance curve for a vegetation canopy might show a peak in the visible and near-infrared regions of the electromagnetic spectrum, indicating that the canopy reflects a large percentage of the EMR in these wavelengths. This can be used to study the health and biomass of the vegetation, as well as to detect the presence of certain minerals in the soil.
Spectral reflectance curves are an important tool in the field of remote sensing because they allow scientists and researchers to study the characteristics of the Earth’s surface and the objects and substances on it in great detail, providing insights into the composition, structure, and dynamics of these systems.

Active and Passive Remote Sensing

Remote sensing refers to the collection of data about the Earth’s surface and atmosphere using sensors and instruments on platforms such as satellites, aircraft, and drones. Remote sensing can be divided into two main categories: active remote sensing and passive remote sensing.

Active remote sensing:

Active remote sensing involves the use of an external energy source, such as a laser or radar, to emit a signal or beam of electromagnetic radiation (EMR) towards the Earth’s surface. The EMR is then reflected back to the sensor by the surface or objects on it, and the characteristics of the reflected EMR are used to study the surface and its features. Active remote sensing systems are typically able to penetrate clouds and other atmospheric conditions, making them useful for studying the Earth’s surface in a variety of conditions. Examples of active remote sensing systems include lidar and radar systems.

Passive remote sensing:

Passive remote sensing involves the detection and measurement of naturally occurring EMR, such as sunlight, reflected or emitted by the Earth’s surface and objects on it. Passive remote sensing systems do not require an external energy source and rely on the natural emission or reflection of EMR to obtain data. Passive remote sensing systems are useful for studying the Earth’s surface in clear conditions, but they may be less effective in cloudy or hazy conditions. Examples of passive remote sensing systems include multispectral and hyperspectral imaging systems.
Both active and passive remote sensing systems have their own unique characteristics and are suited to different types of applications in remote sensing. By selecting the appropriate type of remote sensing system for a given application, scientists and researchers can maximize the amount of useful information that can be obtained from remote sensing data.

Indian Remote Sensing Centers and their Activities

India has a number of remote sensing centers that are responsible for conducting research and development in the field of remote sensing and providing remote sensing data and services to a wide range of users. Some of the major Indian remote sensing centers and their activities are:

• Indian Space Research Organization (ISRO): ISRO is the national space agency of India and is responsible for the development and application of space technology in the country. ISRO operates a number of remote sensing satellites, including the Indian Remote Sensing (IRS) series, which are used for a wide range of applications, including mapping, resource management, and disaster management.
• National Remote Sensing Centre (NRSC): NRSC is a unit of ISRO and is responsible for the processing and dissemination of remote sensing data from Indian and foreign satellite systems. NRSC provides a range of remote sensing data and services, including satellite imagery, digital elevation models, and geospatial products, to users in the government, academia, and the private sector.
• Indian Institute of Remote Sensing (IIRS): IIRS is a training and research institute that is focused on the development of remote sensing technology and its applications in India. IIRS conducts research on a wide range of topics, including land cover mapping, natural resource management, and environmental monitoring, and offers training programs and courses on remote sensing and related technologies.
• North Eastern Space Applications Centre (NESAC): NESAC is a regional remote sensing center that is focused on the development of remote sensing applications in the north-eastern region of India. NESAC conducts research on a wide range of topics, including agriculture, forestry, and natural resource management, and provides remote sensing data and services to users in the region.

These are just a few examples of the Indian remote sensing centers and their activities. In addition to these organizations, there are many other research institutes, universities, and private companies in India that are involved in the development and application of remote sensing technology.

New Satellite Programs of India

India has a number of satellite programs that are focused on the development and operation of satellite systems for a variety of applications, including remote sensing, communication, meteorology, and navigation. Some of the new satellite programs that India is currently working on include:

• GSAT-30: GSAT-30 is a communication satellite that was launched in January 2020 and is being used to provide satellite-based telecommunications services to India and the surrounding region.
• GSAT-20: GSAT-20 is a communication satellite that was launched in May 2020 and is being used to provide satellite-based telecommunications services to India and the surrounding region.
• GSAT-32: GSAT-32 is a communication satellite that was launched in February 2021 and is being used to provide satellite-based telecommunications services to India and the surrounding region.
• GSAT-30: GSAT-30 is a communication satellite that was launched in January 2020 and is being used to provide satellite-based telecommunications services to India and the surrounding region.
• GSAT-29: GSAT-29 is a communication satellite that was launched in November 2018 and is being used to provide satellite-based telecommunications services to India and the surrounding region.
• INSAT-3D: INSAT-3D is a meteorological satellite that was launched in July 2013 and is being used to provide weather forecasting and environmental monitoring services to India and the surrounding region.

These are just a few examples of the new satellite programs that India is currently working on. In addition to these programs, India is also involved in a number of other satellite programs and projects, including the development of satellite-based navigation systems, earth observation satellites, and scientific research satellites.

National Geospatial Policy

The National Geospatial Policy is a policy framework that outlines the principles and guidelines for the development and use of geospatial information and technologies in India. Geospatial information refers to data and information that is related to the location and spatial relationships of objects, features, and phenomena on the Earth’s surface. Geospatial technologies are tools and techniques that are used to acquire, process, analyze, and disseminate geospatial information.
The National Geospatial Policy is designed to promote the responsible and sustainable development and use of geospatial information and technologies in India, with the goal of supporting the country’s economic, social, and environmental development. The policy aims to ensure that geospatial information and technologies are used in an integrated, coordinated, and transparent manner, and that they are accessible to all stakeholders.
The National Geospatial Policy is guided by a number of principles, including:

• Open data: The policy promotes the principles of open data, which means that geospatial data should be made available to all stakeholders in a timely and transparent manner.
• Interoperability: The policy promotes the interoperability of geospatial data, which means that data from different sources should be able to work together seamlessly.
• Security: The policy promotes the security of geospatial data, which means that data should be protected from unauthorized access and use
• Privacy: The policy promotes the privacy of individuals, which means that geospatial data should not be used to infring

Governing Remotely Sensed Data

Remotely sensed data is data that is collected about the Earth’s surface and atmosphere using sensors and instruments on platforms such as satellites, aircraft, and drones. Remotely sensed data is an important resource for a wide range of applications, including mapping, resource management, environmental monitoring, and disaster management.
There are a number of issues that need to be considered when governing remotely sensed data, including:

• Accessibility: Remotely sensed data should be made available to all stakeholders in a timely and transparent manner.
• Interoperability: Remotely sensed data should be able to work seamlessly with other data sources and be compatible with different software and systems.
• Quality: Remotely sensed data should be of high quality and accuracy, and should be properly calibrated and validated.
• Security: Remotely sensed data should be protected from unauthorized access and use, and appropriate measures should be in place to ensure its security.
• Privacy: Remotely sensed data should not be used to infringe on the privacy of individuals, and appropriate measures should be in place to protect personal data.

To address these issues, it is important to have a clear and effective policy framework in place that outlines the principles and guidelines for the development and use of remotely sensed data. This policy framework should be developed in consultation with all relevant stakeholders and should be regularly reviewed and updated to ensure that it is responsive to the changing needs and requirements of the community.