document_title: Two-way radio

question_text: what is the function of the ptt button on a two-way radio

question_tokens: what is the function of the ptt button on a two-way radio

text: Two-way radio

text: History[edit]

text: Installation of receivers and transmitters at the same fixed location allowed exchange of messages wirelessly. As early as 1907, two-way telegraphy traffic across the Atlantic Ocean was commercially available. By 1912 commercial and military ships carried both transmitters and receivers, allowing two-way communication in close to real-time with a ship that was out of sight of land.

text: The first truly mobile two-way radio was developed in Australia in 1923 by Senior Constable Frederick William Downie of the Victorian Police. The Victoria Police were the first in the world to use wireless communication in cars, putting an end to the inefficient status reports via public telephone boxes which had been used until that time. The first sets took up the entire back seat of the Lancia patrol cars.[4]

text: As radio equipment became more powerful, compact, and easier to use, smaller vehicles had two-way radio communication equipment installed. Installation of radio equipment in aircraft allowed scouts to report back observations in real-time, not requiring the pilot to drop messages to troops on the ground below or to land and make a personal report.

text: In 1933, the Bayonne, New Jersey police department successfully operated a two-way system between a central fixed station and radio transceivers installed in police cars; this allowed rapidly directing police response in emergencies.[5] During World War II walkie-talkie hand-held radio transceivers were extensively used by air and ground troops, both by the Allies and the Axis.

text: Early two-way schemes allowed only one station to transmit at a time while others listened, since all signals were on the same radio frequency – this was called "simplex" mode. Code and voice operations required a simple communication protocol to allow all stations to cooperate in using the single radio channel, so that one station's transmissions were not obscured by another's. By using receivers and transmitters tuned to different frequencies, and solving the problems introduced by operation of a receiver immediately next to a transmitter, simultaneous transmission and reception was possible at each end of a radio link, in so-called "full duplex" mode.

text: The first radio systems could not transmit voice. This required training of operators in use of Morse code. On a ship, the radio operating officers (sometimes shortened to "radio officers") typically had no other duties than handling radio messages. When voice transmission became possible, dedicated operators were no longer required and two-way use became more common. Today's two-way mobile radio equipment is nearly as simple to use as a household telephone, from the point of view of operating personnel, thereby making two-way communications a useful tool in a wide range of personal, commercial and military roles.

text: Types[edit]

text: Two-way radio systems can be classified in several ways depending on their attributes.

text: Conventional versus trunked[edit]

text: Conventional[edit]

text: Conventional radios operate on fixed RF channels. In the case of radios with multiple channels, they operate on one channel at a time. The proper channel is selected by a user. The user operates a channel selector (dial or buttons) on the radio control panel to pick the appropriate channel.

text: In multi-channel systems, channels are used for separate purposes.[6] A channel may be reserved for a specific function or for a geographic area. In a functional channel system, one channel may allow City of Springfield road repair crews to talk to the City of Springfield's road maintenance office. A second channel may allow road repair crews to communicate with state highway department crews. In a geographic system, a taxi company may use one channel to communicate in the Boston, Massachusetts area and a second channel when taxis are in Providence, Rhode Island. In marine radio operations, one channel is used as an emergency and calling channel, so that stations may make contact then move to a separate working channel for continued communication.

text: Motorola uses the term mode to refer to channels on some conventional two-way radio models. In this use, a mode consists of a radio frequency channel and all channel-dependent options such as selective calling, channel scanning, power level, and more.

text: Scanning in conventional radios[edit]

text: Some conventional radios scan more than one channel. That is, the receiver searches more than one channel for a valid transmission. A valid transmission may be a radio channel with any signal or a combination of a radio channel with a specific Continuous Tone-Coded Squelch System (CTCSS) (or selective calling) code.

text: There are a wide variety of scan configurations which vary from one system to another. Some radios have scan features that receive the primary selected channel at full volume and other channels in a scan list at reduced volume. This helps the user distinguish between the primary channel and others without looking at the radio control panel. An overview:

text:
A scanning feature can be defined and preset: when in scanning mode, a predetermined set of channels is scanned. Channels are not changeable by the radio user.
Some radios allow an option for user-selected scan: this allows either lockout of pre-selected channels or adding channels to a scan list by the operator. The radio may revert to a default scan list each time it is powered off or may permanently store the most recent changes.

text: In professional radios, scan features are programmable and have many options. Scan features can affect system latency. If the radio has a twenty channel scan list and some channels have CTCSS, it can take several seconds to search the entire list. The radio must stop on each channel with a signal and check for a valid CTCSS before resuming scanning. This can cause missed messages.

text: For this reason, scan features are either not used or scan lists are intentionally kept short in emergency applications. Part of APCO Project 16 set standards for channel access times and delays caused by system overhead. Scan features can further increase these delays. One study said delays of longer than 0.4 seconds (400 milliseconds) in emergency services are not recommended.[7] No delay from user push-to-talk until the user's voice is heard in the radio's speaker is an unattainable ideal.

text: Talk-back on scan[edit]

text: Some conventional radios use, or have an option for, a talk-back-on-scan function. If the user transmits when the radio is in a scan mode, it may transmit on the last channel received instead of the selected channel. This may allow users of multi-channel radios to reply to the last message without looking at the radio to see which channel it was on. Without this feature, the user would have to use the channel selector to switch to the channel where the last message occurred. (This option can cause confusion and users must be trained to understand this feature.)

text: This is an incomplete list of some conventional radio types:

text:
Commercial and Public Safety Radio
Marine VHF radio
Family Radio Service (sometimes referred to by the abbreviation FRS)
UNICOM
Amateur radio

text: Trunked[edit]

text: In a trunked radio system, the system logic automatically picks the physical radio frequency channel. There is a protocol that defines a relationship between the radios and the radio backbone which supports them. The protocol allows channel assignments to happen automatically.

text: Digital trunked systems may carry simultaneous conversations on one physical channel. In the case of a digital trunked radio system, the system also manages time slots on a single physical channel. The function of carrying simultaneous conversations over a single channel is called multiplexing.

text: Instead of channels, radios are related by groups which may be called, groups, talk groups, or divided into a hierarchy such as fleet and subfleet, or agency-fleet-subfleet. These can be thought of as virtual channels which appear and disappear as conversations occur.

text: Systems make arrangements for handshaking and connections between radios by one of these two methods:

text:
A computer assigns channels over a dedicated control channel. The control channel sends a continual data stream. All radios in the system monitor the data stream until commanded by the computer to join a conversation on an assigned channel.
Electronics embedded in each radio communicate using a protocol of tones or data in order to establish a conversation, (scan-based).

text: If all physical channels are busy, some systems include a protocol to queue or stack pending requests until a channel becomes available.

text: Some trunked radios scan more than one talk group or agency-fleet-subfleet.

text: Visual clues a radio may be trunked include the 1) lack of a squelch knob or adjustment, 2) no monitor button or switch, and 3) a chirp (made famous by Nextel) showing the channel is available and ready at the moment the push-to-talk is pressed.

text: This is an incomplete list of some trunked radio types:

text:
TETRA
Logic Trunked Radio (abbreviated LTR)
SmartZone and SmartNet
EDACS

text: Simplex versus duplex channels[edit]

text: Simplex[edit]

text: Simplex channel systems use a single channel for transmit and receive. This is typical of aircraft VHF AM, citizen's band and marine radios. Simplex systems are often legacy systems that have existed since the 1930s. The architecture allows old radios to work with new ones in a single network. In the case of all ships worldwide or all aircraft worldwide, the large number of radios installed, (the installed base,) can take decades to upgrade. Simplex systems often use open architectures that allow any radio meeting basic standards to be compatible with the entire system.

text:
Advantage: as the simplest system configuration, there is reliability since only two radios are needed to establish communication between them, without any other infrastructure.
Disadvantages: The simplex configuration offers communication over the shortest range or distance because mobile units must be in effective range of each other. The available channel bandwidth limits the number of simultaneous conversations, since "dead" air time cannot be easily used for additional communication.

text: Duplex[edit]

text: Duplex channel systems transmit and receive on different discrete channels. This defines systems where equipment cannot communicate without some infrastructure such as a repeater, base station or Talk-Through Base. Most common in the US is a repeater configuration where a base station is configured to simultaneously re-transmit the audio received from mobile units. This makes the mobiles, or hand-helds, able to communicate amongst one another anywhere within reception range of the base station or repeater. Typically the base or repeater station has a high antenna and high power, which allows much greater range, compared with a ground vehicle or hand-held transceiver.

text: Duplex systems can be divided into two types. The term half-duplex refers to systems where use of a push-to-talk switch is required to communicate. Full duplex refers to systems like mobile telephones with a capability to simultaneously receive and transmit. Repeaters are by nature full duplex, most mobiles and almost all handhelds are half duplex.

text:
Advantage: duplex channels usually allow repeater operation which extends range (in most cases due to increased transmit power and improved aerial location / height) – especially where hand-held radios are in use.
Disadvantage: If a radio cannot reach the repeater, it cannot communicate.

text: Hybrid simplex/duplex[edit]

text: Some systems use a mix of the two where radios use duplex as a default but can communicate simplex on the base station channel if out-of-range.[8] In the US, the capability to talk simplex on a duplex channel with a repeater is sometimes called talk-around, direct, or car-to-car.

text: Push-to-Talk (PTT)[edit]

text: In two-way radios with headsets, a push-to-talk button may be included on a cord or wireless electronics box clipped to the user's clothing. In fire trucks or an ambulance a button may be present where the corded headset plugs into the radio wiring. Aircraft typically have corded headsets and a separate push-to-talk button on the control yoke or control stick. Dispatch consoles often have a hand-operated push-to-talk buttons along with a foot switch or pedal. If the dispatcher's hands are on a computer keyboard, the user can step on the foot pedal to transmit. Some systems have muting so the dispatcher can be on a telephone call and the caller cannot hear what is said over the radio. Their headset microphone will mute if they transmit. This relieves the dispatcher of explaining every radio message to a caller.

text: In some circumstances, voice-operated transmit (VOX) is used in place of a push-to-talk button. Possible uses are handicapped users who cannot push a button, amateur radio operators, firefighters, crane operators, or others performing critical tasks where hands must be free but communication is still necessary.

text: Analog versus digital[edit]

text: One example of analog radios are AM aircraft radios used to communicate with control towers and air traffic controllers. Another is a Family Radio Service walkie talkie. Analog equipment is less complex than the simplest digital.

text:
Advantage: In high-quality equipment, better ability to communicate in cases where a received signal is weak or noisy.
Disadvantage: Only one conversation at a time can occur on each channel.

text: Examples of digital communication technologies are all modern cellphones plus TETRA considered to be the best standard in digital radio and being the baseline infrastructure for whole of country networks, including manufacturers such as DAMM, Rohill, Cassidian, Sepura and others, APCO Project 25, a standard for digital public safety radios, and finally other systems such as Motorola's MotoTRBO, HQT's DMR, Nextel's iDEN, Hytera's DMR, EMC's DMR, and NXDN implemented by Icom as IDAS and by Kenwood as NEXEDGE. Only NXDN and Mototrbo are proprietary DMR is an ETSI open standard.

text:
Advantage: More simultaneous talking paths are possible and information such as unit ID, status buttons, or text messages can be embedded into a single digital radio channel. The interoperability standard of TETRA means that any brand TETRA radio can work with any Brand TETRA infrastructure, not locking the user into expensive and proprietary systems.
Disadvantage: Radios must be designed to the same, compatible standard, radios can become obsolete quickly (although this is mitigated by properly implemented interoperability standards such as those set down by ETSI for TETRA), cost more to purchase, and are more complicated.

text: Data over two-way radio[edit]

text: In some cases, two-way radio is used to communicate analog or digital data. Systems can be simplex or duplex and may employ selective calling features such as CTCSS. In full-duplex systems, data can be sent real-time between two points. In simplex or half-duplex, data can be sent with a time lag between many points.

text: Some two-way digital systems carry both audio and data over a single data stream. Systems of this type include NXDN and APCO Project 25. Other more advanced systems under the TETRA standard are capable of joining time slots together to improve data bandwidth, allowing advanced data polling and telemetry applications over radio. The method of encoding and decoding the audio stream is called a codec, such as the AMBE or the ACELP family of codecs.

text: After market GPS tracking and mobile messaging devices can be interfaced with popular two-way radio models providing a range of features.

text: Analog[edit]

text: Analog systems may communicate a single condition, such as water level in a livestock tank. A transmitter at the tank site continually sends a signal with a constant audio tone. The tone would change in pitch to indicate the tank's water level. A meter at the remote end would vary, corresponding to the tone pitch, to indicate the amount of water present in the livestock tank. Similar methods can be used to telemeter any analog condition. This type of radio system serves a purpose equivalent to a four-to-twenty milliampere loop.[9] In the US, mid-band 72–76 MHz or UHF 450–470 MHz interstitial channels are often used for these systems. Some systems multiplex telemetry of several analog conditions by limiting each to a separate range of tone pitches, for example.[10]

text: Digital[edit]

text: Digital systems may communicate text messages from computer-aided dispatch (CAD). For example, a display in a tow truck may give a textual location for a call and any related details. The tow truck driver may press an acknowledge button, sending data in the opposite direction and flagging the call as received by the driver. They can be used for analog telemetry systems, such as the livestock tank levels, as described above. Another possibility is the lubricating oil pressure in a transit bus engine, or the current speed of the bus. Analog conditions are translated into data words. Some systems send radio paging messages which can either 1) beep a paging receiver, 2) send a numeric message, or 3) send a text message.[11]

text: Digital systems typically use data rates in the 1,200–19,200 kilobit-per-second rates and may employ modulation schemes such as frequency shift keying, audio frequency shift keying, or quadrature phase shift keying to encode characters. Modern equipment have the same capabilities to carry data as are found in Internet Protocol. Working within the system's protocol constraints, virtually anything can be sent or received.

text: Engineered versus not engineered[edit]

text: Engineered systems are designed to perform close to a specification or standard. They are designed as systems with all equipment matched to perform together. For example, a modern, local government two-way radio system in the US may be designed to provide 95% area coverage in an urban area. System designers use radio frequency models, terrain models, and signal propagation modeling software in an attempt to accurately estimate where radios will work within a defined geographic area. The models help designers choose equipment, equipment locations, antennas, and estimate how well signals will penetrate buildings. These models will be backed-up by drive testing and actual field signal level measurements. Designers adjust antenna patterns, add or move equipment sites, and design antenna networks in a way that will accomplish the intended level of performance.[12]

text: Some systems are not engineered. Legacy systems are existing systems which were never designed to meet a system performance objective. They may have started with a base station and a group of mobile radios. Over a period of years, they have equipment added on in a building block style. Legacy systems may perform adequately even though they were not professionally designed as a coherent system. A user may purchase and locate a base station with an expectation that similar systems used in the past worked acceptably. A City Road Department may have a system that works acceptably, so the Parks Department may build a new similar system and find it equally usable. General Mobile Radio Service systems are not usually engineered.

text: Options, duty cycle, and configuration[edit]

text: 1940s tube-type land mobile two way radios often had one channel and were carrier squelch. Because radios were costly and there were fewer radio users, it might be the case that no one else nearby used the same channel. A transmit and receive crystal had to be ordered for the desired channel frequency, then the radio had to be tuned or aligned to work on the channel. 12-volt mobile, tube-type radios drew several amperes on standby and tens-of-amperes on transmit. Equipment worked ideally when new. The performance of vacuum tubes gradually degraded over time. US regulations required an indicator lamp showing the transmitter had power applied and was ready to transmit and a second indicator, (usually red,) that showed the transmitter was on. In radios with options, wire jumpers and discrete components were used to select options. To change a setting, the technician soldered an option jumper wire then made any corresponding adjustments.

text: Many mobile and handhelds have a limited duty cycle. Duty Cycle is the ratio of listening time to transmit time and is generally dependent on how well the transmitter can shed the heat from the heat sink on the rear of the radio. A 10% duty cycle (common on handhelds) translates to 10 seconds of transmit time to 90 seconds of receive time. Some mobile and base equipment is specified at different power levels – for example 100% duty cycle at 25 watts and 15% at 40 watts.[13]

text: The trend is toward increasing complexity. Modern handheld and mobile radios can have capacities as high as 255 channels. Most are synthesized: the internal electronics in modern radios operate over a range of frequencies with no tuning adjustments. High-end models may have several hundred optional settings and require a computer and software to configure. Sometimes, controls on the radio are referred to as programmable. By changing configuration settings, a system designer could choose to set up a button on the radio's control panel to function as:

text:
turn scan on or off,
alert another mobile radio, (selective calling),
turn on an outside speaker, or
select repeater locations.

text: In most modern radios these settings are done with specialized software (provided by the manufacturer) and a connection to a laptop computer.

text: Microprocessor-based radios can draw less than 0.2 amperes on standby and up to tens-of-amperes on high-powered, 100 watt transmitters.

text: Base stations, repeaters, and high-quality mobile radios often have specifications that include a duty cycle. A repeater should always be continuous duty. This means the radio is designed to transmit in a continuous broadcast without transmitter overheating and resulting failure. Handhelds are intermittent duty, mobile radios and base station radios are available in normal or continuous duty configurations. Continuous duty is preferred in mobile emergency equipment because any one of an entire fleet of ambulances, for example, could be pressed into service as command post at a major incident. Unfortunately budgets frequently get in the way and intermittent duty radios are purchased.

text: Time delay is always associated with radio systems, but it is apparent in spacecraft communications. NASA regularly communicates with exploratory spacecraft where a round-trip message time is measured in hours (like out past Jupiter). For Apollo program and Space Shuttle, Quindar tones were used for transmit PTT control.

text: Life of equipment[edit]

text: Though the general life term for the two way radio is 5 to 7 years and 1 to 2 years for its accessories but still the usage, atmosphere and environment plays a major role to decide its life term (radios are often deployed in harsh environments where more fragile communication equipment such as phones and tablets may fail). There are so many speculations on the life term of two way radios and their accessories i.e. batteries, chargers, head set etc.

text: In government systems, equipment may be replaced based on budgeting rather than any plan or expected service life. Funding in government agencies may be cyclical or sporadic. Managers may replace computing systems, vehicles, or budget computer and vehicle support costs while ignoring two-way radio equipment. Equipment may remain in use even though maintenance costs are unreasonable when viewed from an efficiency standpoint.[14]

text: Different system elements will have differing service lifetimes. These may be affected by who uses the equipment. An individual contacted at one county government agency claimed equipment used by 24-hour services wears out much faster than equipment used by those who work in positions staffed eight hours a day.

text: One document says "seven years" is beyond the expected lifetime of walkie-talkies in police service. Batteries are cited as needing replacement more often. Twelve-year-old dispatch consoles mentioned in the same document were identified as usable. These were compared to problematic 21-year-old consoles used elsewhere in the same system.[15]

text: Another source says system backbone equipment like consoles and base stations are expected to have a fifteen-year life. Mobile radios are expected to last ten years. Walkie talkies typically last eight.[16] In a State of California document, the Department of General Services reports expected service life for a communications console used in the Department of Forestry and Fire Protection is 10 years.[17]

text: Two-way radio frequencies[edit]

text: The examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject. You may improve this article, discuss the issue on the talk page, or create a new article, as appropriate. (October 2012) (Learn how and when to remove this template message)

text: Two-way radios can operate on many different frequencies, and these frequencies are assigned differently in different countries. Typically channelized operations are used, so that operators need not tune equipment to a particular frequency but instead can use one or more pre-selected frequencies, easily chosen by a dial, a pushbutton or other means. For example, in the United States, there is a block of 5 channels (pre-selected radio frequencies) are allocated to the Multiple Use Radio System. A different block of 22 channels are assigned, collectively, to the General Mobile Radio Service and Family Radio Service. The citizen's band radio service (""CB"") has 40 channels.

text: In an analog, conventional system, (the simplest type of system) a frequency or channel serves as a physical medium or link carrying communicated information. The performance of a radio system is partly dependent on the characteristics of frequency band used. The selection of a frequency for a two-way radio system is affected, in part, by:[18]

text:
government licensing and regulations.
local congestion or availability of frequencies.
terrain, since radio signals travel differently in forests and urban viewsheds.
the presence of noise, interference, or intermodulation.
sky wave interference below 50–60 MHz and tropospheric bending at VHF.
in the US, some frequencies require approval of a frequency coordination committee.

text: A channel number is just a shorthand notation for a frequency. It is, for instance, easier to remember "Channel 1" than to remember "26.965 MHz" (US CB Channel 1) or "462.5625 MHz" (FRS/GMRS channel 1), or "156.05 MHz" (Marine channel 1). It is necessary to identify which radio service is under discussion when specifying a frequency by its channel number. Organizations, such as electric power utilities or police departments, may have several assigned frequencies in use with arbitrarily assigned channel numbers. For example, one police department's "Channel 1" might be known to another department as "Channel 3" or may not even be available. Public service agencies have an interest in maintaining some common frequencies for inter-area or inter-service coordination in emergencies (modern term: interoperability).

text: Each country allocates radio frequencies to different two-way services, in accordance with international agreements. In the United States some examples of two-way services are: citizen's band radio, Family Radio Service (FRS), General Mobile Radio Service (GMRS), Multi-Use Radio Service (MURS), Business Radio Service (BRS), and PMR446.

text: Amateur radio operators nearly always use frequencies rather than channel numbers, since there is no regulatory or operating requirement for fixed channels in this context. Even amateur radio equipment will have "memory" features to allow rapidly setting the transmitter and receiver to favorite frequencies.

text: UHF versus VHF[edit]

text: The most common two-way radio systems operate in the VHF and UHF parts of the radio spectrum. Because this part of the spectrum is heavily used for broadcasting and multiple competing uses, spectrum management has become an important activity of governments to regulate radio users in the interests of efficient and non-interfering use of radio. Both bands are widely applied for different users.

text: UHF has a shorter wavelength which makes it easier for the signal to find its way through smaller wall openings to the inside of a building. The longer wavelength of VHF means it can transmit further under normal conditions. For most applications, lower radio frequencies are better for longer range and through vegetation. A broadcasting TV station illustrates this. A typical VHF TV station operates at about 100,000 watts and has a coverage radius range of about 60 miles. A UHF TV station with a 60-mile coverage radius requires transmitting at 3,000,000 watts. Another factor with higher frequencies (UHF) is that smaller sized objects will absorb or reflect the energy more which causes range loss and/or multipath reflections which can weaken a signal by causing an "Out of Time/Out of Phase" signal to reach the antenna of the receiver (this is what caused the "Ghost" image on old over the air television).

text: If an application requires working mostly outdoors, a VHF radio is probably the best choice, especially if a base station radio indoors is used and an external antenna is added. The higher the antenna is placed, the further the radio can transmit and receive.

text: If the radios are used mainly inside buildings, then UHF is likely the best solution since its shorter wavelength travels through small openings in the building better. There are also repeaters that can be installed that can relay any frequencies signal (VHF or UHF) to increase the communication distance.

text: There are more available channels with UHF. Since the range of UHF is also not as far as VHF under most conditions, there is less chance of distant radios interfering with the signal. UHF is less affected than VHF by manmade electrical noise. So as you see, radio technology is very dynamic and you must make the choice of what to use based on your individual situation.

text: Range[edit]

text: The useful direct range of a two-way radio system depends on radio propagation conditions, which are a function of frequency, antenna height and characteristics, atmospheric noise, reflection and refraction within the atmosphere, transmitter power and receiver sensitivity, and required signal-to-noise ratio for the chosen modulation method. An engineered two-way radio system will calculate the coverage of any given base station with an estimate of the reliability of the communication at that range. Two-way systems operating in the VHF and UHF bands, where many land mobile systems operate, rely on line-of-sight propagation for the reliable coverage area. The "shadowing" effect of tall buildings may block reception in areas within the line-of-sight range which can be achieved in open countryside free of obstructions. The approximate line-of-sight distance to the radio horizon can be estimated from : horizon in kilometers = 3.569 times the square root of the antenna height in meters.

text: There are other factors that affect the range of a two-way radio such as weather, exact frequency used, and obstructions.[19]

text: Other two-way radio devices[edit]

text: Not all two way radios are hand-held devices. The same technology that is used in two way radios can be placed in other radio forms. An example of this is a wireless callbox. A wireless callbox is a device that can be used for voice communication at security gates and doors. Not only can they be used to talk to people at these entry points, personnel can remotely unlock the door so the visitor can enter. There are also customer service callboxes that can be placed around a business that a customer can use to summon help from a two-way radio equipped store employee.

text: Another use of two-way radio technology is for a wireless PA system. A wireless PA is essentially a one-way two way radio that enables broadcasting messages from handheld two-way radios or base station intercoms.

text: Two-way radio rental business[edit]

text: As two-way radios became the leading method of two-way communication, industries like movie and television production companies, security companies, event companies, sporting events and others needed to find a solution to use two way radios that was cost-effective and economically smart. Instead of buying two-way radios these companies began renting two-way radios short term and long term. The two-way radio rentals is a significant and important component of two-way radio businesses. Many have become reluctant to buy two way radios because of the duration of their event or the necessity to save money. Renting two way radios has brought comfort to customers in renting two way radios because the price and non commitment to owning such two way communication devices. Customers can rent anything from two-way radios to two-way radio equipment like speaker microphones or repeaters.


document_title: Bad and Boujee

question_text: who sings the chorus in bad and boujee

question_tokens: who sings the chorus in bad and boujee

root

text: Bad and Boujee

text: Critical reception[edit]

text: Complex placed it at number 24 on its The 50 Best Songs of 2016 list, saying; "The track is lurching and confident, the kind of song that's sure of its own appeal but knows not to step outside of the pocket. It seems like an unlikely hit, but try listening just once".[6] Pigeons & Planes ranked it at number 43 on their Best Songs of 2016 list, saying that the "track is really all about Offset".[7] The Fader ranked the song at number 25 on its The 115 Best Songs of 2016 list.[8] Fact named it as one of the 20 best rap and R&B tracks of 2016.[9] Vulture favorably compared "Bad and Boujee" to James Brown's song "Super Bad".[10]

tag: p

text: Chart performance[edit]

text: The song reached number one on the Billboard Hot 100, making it the first chart-topping single for both Migos and Lil Uzi Vert. A week after its peak, it was dethroned by Ed Sheeran's "Shape of You", but retrieved its peak position the following week and stood there for two more weeks before being replaced by "Shape of You" again, until the latter was surpassed by Kendrick Lamar's "Humble".[11]

text: "Bad and Boujee" has also peaked at number five in Canada, making it Migos and Lil Uzi Vert's first charted single in that country. As of June 20, 2017, the song has sold 4,000,000 units in the United States.[12] The song was certified 4× Platinum by the Recording Industry Association of America (RIAA).

text: Music video[edit]

text: The Daps-directed music video for "Bad and Boujee" premiered via Migos' YouTube channel on October 31, 2016.[13] It features cameo appearances from rappers Travis Scott and OG Maco.[13]

text: In an interview with Kiss FM Kenya, director Daps revealed the inspiration behind the concept of the viral music video: "The concept came about from the title really. 'Bad' is good looking so we needed pretty ladies and 'boujee' is stuck up so we needed them to play that part. I like having juxtapositions in my videos as it makes the art stand out. The contrast between these ladies dressed in high fashion but having them in regular environments grasped me. Then it was about adding in little elements after that — the doves, the noodles, ace of spades, silk shirts on a dirt bike."[14]

text: As of October 2017[update], the video on YouTube has over 500 million views.[15]

text: Response to Takeoff's omission[edit]

text: While he can be seen in one of the background scenes in the music video, Takeoff is not featured nor credited on the song. Takeoff himself has stated that he was not featured because he was busy at the time. On June 24, 2017, during filming of Complex's Everyday Struggle, he was questioned about his absence, to which he replied, "Do it look like I'm left off 'Bad and Boujee'?"[16] Since the interview numerous Internet memes have appeared, mocking his response as the interviewers could not hear him properly, asking him to repeat the answer and leaning towards him to hear better. They later stated that the reason they could not hear his answer was because there was a lot of noise around them and he was not speaking loud enough, but fans have made jokes that he was not speaking clearly, often jokingly posting excessively misspelled quotes of the response on social media, implying that Takeoff mumbled while responding to the question.

text: Live performances[edit]

text: On January 17, 2017, Migos performed the song on Jimmy Kimmel Live!.[17] On February 20, they performed it on The Ellen DeGeneres Show.[18]

text: Media usage[edit]

text: The song is featured in the television show Black-ish.

text: Charts[edit]

text:
Chart (2016–17)
Peak
position

Australia (ARIA)[19]
34

Australia Urban (ARIA)[20]
3

Belgium (Ultratop 50 Flanders)[21]
50

Belgium (Ultratip Wallonia)[22]
25

Canada (Canadian Hot 100)[23]
5

Czech Republic (Singles Digitál Top 100)[24]
69

Denmark (Tracklisten)[25]
39

France (SNEP)[26]
91

Germany (Official German Charts)[27]
65

Ireland (IRMA)[28]
40

Netherlands (Single Top 100)[29]
41

New Zealand (Recorded Music NZ)[30]
17

Norway (VG-lista)[31]
29

Philippines (Philippine Hot 100)[32]
47

Portugal (AFP)[33]
34

Scotland (Official Charts Company)[34]
87

Sweden (Sverigetopplistan)[35]
37

Switzerland (Schweizer Hitparade)[36]
31

UK Singles (Official Charts Company)[37]
30

US Billboard Hot 100[38]
1

US Hot R&B/Hip-Hop Songs (Billboard)[39]
1

US Mainstream Top 40 (Billboard)[40]
31

US Rhythmic (Billboard)[41]
1

tag: table

text: Certifications[edit]

text:
Region
Certification
Certified units/Sales

Australia (ARIA)[42]
Platinum
70,000^

New Zealand (RMNZ)[43]
Gold
15,000*

United Kingdom (BPI)[44]
Silver
200,000

United States (RIAA)[45]
4× Platinum
4,000,000

*sales figures based on certification alone
^shipments figures based on certification alone
sales+streaming figures based on certification alone


document_title: Constituent Assembly of India

question_text: who was appointed as the chairman of the drafting committee of the constitution

text: Constituent Assembly of India

text: Description [edit]

text: The Constituent Assembly, consisting of indirectly elected representatives, was established to draft a constitution for India (including the now-separate countries of Pakistan and Bangladesh). It existed for almost three years, the first parliament of India after independence in 1947. The Assembly was not elected on the basis of universal adult suffrage, and Muslims and Sikhs received special representation as minorities. The Muslim League boycotted the Assembly after failing to prevent its creation. Although a large part of the Constituent Assembly was drawn from the Congress Party in a one-party environment, the Congress Party included a wide diversity of opinions—from conservative industrialists and radical Marxists to Hindu revivalists—all of whom participated in the process.

text: The Assembly met for the first time in New Delhi on 9 December 1946, and its last session was held on 24 January 1950.[1] During this period (two years, eleven months and eighteen days) the Assembly held eleven sessions, sitting for a total of 166 days.[2] The hope of the Assembly was expressed by Jawaharlal Nehru:

text: The first task of this Assembly is to free India through a new constitution, to feed the starving people, and to clothe the naked masses, and to give every Indian the fullest opportunity to develop himself according to his capacity. This is certainly a great task. Look at India today. We, are sitting here and there in despair in many places, and unrest in many cities. The atmosphere is surcharged with these quarrels and feuds which are called communal disturbances, and unfortunately we sometimes cannot avoid them. But at present the greatest and most important question in India is how to solve the problem of the poor and the starving. Wherever we turn, we are confronted with this problem. If we cannot solve this problem soon, all our paper constitutions will become useless and purposeless. Keeping this aspect in view, who could suggest to us to postpone and wait?

text: Background and election[edit]

text: The Constituent Assembly was established while India was still under British rule, following negotiations between Indian leaders and members of the 1946 Cabinet Mission to India from the United Kingdom. Provincial assembly elections were held early in 1946. Constituent Assembly members were elected indirectly by members of the newly elected provincial assemblies, and initially included representatives for those provinces which formed part of Pakistan (some of which are now in Bangladesh). The Constituent Assembly had 299 representatives, including nine women.

text: The Interim Government of India was formed on 2 September 1946 from the newly elected Constituent Assembly. The Congress held a large majority in the Assembly (69 percent of the seats), and the Muslim League held nearly all the seats reserved in the Assembly for Muslims. There were also members of smaller parties, such as the Scheduled Caste Federation, the Communist Party of India and the Unionist Party.

text: In June 1947 delegations from Sindh, East Bengal, Baluchistan, West Punjab and the North West Frontier Province withdrew to form the Constituent Assembly of Pakistan, meeting in Karachi. On 15 August 1947 the Dominion of India and Dominion of Pakistan became independent nations, and members of the Constituent Assembly who had not withdrawn to Karachi became India's Parliament. Twenty-eight members of the Muslim League joined the Indian Assembly, and 93 members were later nominated from the princely states; the Congress Party secured a majority of 82 percent.

text: Constitution and elections[edit]

text: At 11 am on 9 December 1946 the Assembly began its first session, with 208 members attending.  By early 1947, representatives of the Muslim League and princely states joined, and the Assembly approved the draft constitution on 26 November 1949. On 26 January 1950 the constitution took effect (commemorated as Republic Day), and the Constituent Assembly became the Provisional Parliament of India (continuing until after the first elections under the new constitution in 1952).

text: Organization[edit]

text: Dr. Sachchidananda Sinha was the first chairman (temporary) of Constituent Assembly. Later Dr. Rajendra Prasad was elected as the president and Its vice-president was Harendra Coomar Mookerjee, a Christian from Bengal and former vice-chancellor of Calcutta University. Also chairing the assembly's Minorities Committee, Mookerjee was appointed governor of West Bengal after India became a republic. Jurist B. N. Rau was appointed constitutional adviser to the assembly; Rau prepared the original draft of the constitution, and was later appointed a judge in the Permanent Court of International Justice in The Hague.

text: The assembly's work had five stages:

text:
Committees presented reports on issues.
B.N. Rau prepared an initial draft based on the reports and his research into the constitutions of other nations.
The drafting committee, chaired by B. R. Ambedkar, presented a detailed draft constitution which was published for public discussion.
The draft constitution was discussed, and amendments proposed and enacted.
The constitution was adopted, with a committee of experts led by the Congress Party (known as the Congress Assembly Party) played a pivotal role.[3]

tag: ul

text: Timeline[edit]

text:
9 December 1946: The first meeting of the Constituent Assembly was held in the constitution hall (now the Central Hall of Parliament House). Demanding a separate state, the Muslim League boycotted the meeting. Sachchidananda Sinha was elected temporary president of the assembly, in accordance with French practice.
11 December 1946: Rajendra Prasad was elected as president and H. C. Mukherjee was elected as vice-president of the constituent assembly. B. N. Rau was appointed as its constitutional adviser.
13 December 1946: An 'Objective Resolution' was moved by Jawaharlal Nehru in the assembly, laying down the underlying principles of the constitution. It finally became the Preamble of the constitution.
22 January 1947: Objective resolution unanimously adopted.
22 July 1947: National flag adopted.
15 August 1947: Indian independence achieved as the Dominion of India.
29 August 1947: Drafting Committee appointed with Dr. B. R. Ambedkar as the Chairman.
16 July 1948: Along with Harendra Coomar Mookerjee V. T. Krishnamachari was also elected as second vice-president of Constituent Assembly.
26 November 1949: Constitution passed and accepted by the assembly.
24 January 1950: "Jana Gana Mana" adopted as the national anthem, with the first two verses of "Vande Mataram" the national song. Rajendra Prasad elected the first president of India.

text: The assembly was chaired by Dr. Rajendra Prasad when it met as a constituent body, and by G. V. Mavlankar when it met as a legislative body. It completed the task of drafting a constitution in two years, eleven months and eighteen days, at a total expenditure of ₹6.4 million.

text: Committees of the Constituent Assembly[edit]

text: The Constituent Assembly appointed a total of 22 committees to deal with different tasks of constitution-making. Out of these, eight were major committees and the others were minor committees.

text: Major Committees

text:
Drafting Committee – Dr. B.R. Ambedkar
Union Powers Committee – Jawaharlal Nehru
Union Constitution Committee – Jawaharlal Nehru
Provincial Constitution Committee – Sardar Patel
Advisory Committee on Fundamental Rights, Minorities and Tribal and Excluded Areas – Sardar Patel.	This committee had the following subcommittees:
Fundamental Rights Sub-Committee – J.B. Kripalani
Minorities Sub-Committee – Harendra Coomar Mookerjee,
North-East Frontier Tribal Areas and Assam Excluded & Partially Excluded Areas Sub-Committee – Gopinath Bardoloi
Excluded and Partially Excluded Areas (Other than those in Assam) Sub-Committee – A V Thakkar
Rules of Procedure Committee – Dr. Rajendra Prasad
States Committee (Committee for Negotiating with States) – Jawaharlal Nehru
Steering Committee – Dr. Rajendra Prasad

tag: ol

text: Prominent members[edit]

text:
B. R. Ambedkar, Minister for Law; Chairman of Drafting Committee
B. N. Rau, Constitutional Advisor
Jawaharlal Nehru, first Prime Minister of India
Sardar Vallabhbhai Patel, first Deputy Prime Minister and Home Minister
Maulana Abul Kalam Azad, Minister for Education
Rajendra Prasad, President of Constituent Assembly
C. Rajagopalachari, Governor-General of India
Sarat Chandra Bose, Barrister and Indian independence activist
Krishna Sinha, first Chief Minister, Bihar
Binodanand Jha,  Minister, Bihar
Shyam Nandan Prasad Mishra
Anugrah Narayan Sinha, Deputy Chief Minister and Finance Minister, Bihar
Rafi Ahmed Kidwai
Asaf Ali
Syama Prasad Mookerjee, Industries Minister, President, Hindu Mahasabha
Moturi Satyanarayana, Freedom Fighter
Rajkumari Amrit Kaur, Health Minister
Hansa Mehta, President, All India Women's Conference
N. G. Ranga
Deep Narayan Singh, Minister, Bihar
Gopinath Bordoloi, Prime Minister of Assam[4]
Sir Syed Muhammad Saadulla, Assam
P. Subbarayan
Kailashnath Katju
N. Gopalaswami Ayyangar
T. T. Krishnamachari
Rameshwar Prasad Sinha
Durgabai Deshmukh
K. M. Munshi
Krishana Ballabh Sahay
Frank Anthony, Anglo-Indian representative
Sarvepalli Radhakrishnan
John Mathai,first railway minister of India
Pratap Singh Kairon
L. Krishnaswamy Bharati - Madras Province
Chidambaram Subramaniam
Jaipal Singh Munda, Former Indian Hockey captain, and Tribal leader

text: Members (by province/state)[edit]

text:
Madras:
Annie Mascarene, O. V. Alagesan,
Mrs. Ammu Swaminathan,
M. Ananthasayanam Ayyangar,
Moturi Satyanarayana,
Mrs. Dakshayani Velayudhan,
Mrs. G. Durgabai,
Kala Venkatarao,
N. Gopalaswamy Ayyangar,
D. Govinda Das,
Revd. Jerome D'Souza,
P. Kakkan,
T.M. Kaliyannan Gounder,
K. Kamaraj,
V. C. Kesava Rao,
T. T. Krishnamachari,
Alladi Krishnaswamy Iyer
L. Krishnaswami Bharathi,
P. Kunhiraman,
Mosalikanti Thirumala Rao,
V. I. Munuswamy Pillai,
M. A. Muthiah Chettiar,
V. Nadimuthu Pillai,
S. Nagappa,
P. L. Narasimha Raju,
B. Pattabhi Sitaramayya,
C. Perumalswamy Reddy,
T. Prakasam,
S. H. Prater,
Raja Swetachalapati Ramakrishna Renga Roa of Bobbili,
R. K. Shanmukham Chetty,
T. A. Ramalingam Chettiar,
Ramnath Goenka,
O. P. Ramaswamy Reddiar,
N. G. Ranga,
Neelam Sanjeeva Reddy,
Sheik Galib Sahib,
K. Santhanam,
B. Shiva Rao,
Kallur Subba Rao,
U. Srinivasa Mallya,
P. Subbarayan,
C. Subramaniam,
V Subramaniam,
M. C. Veerabahu Pillai,
P. M. Velayudapani,
A. K. Menon,
T. J. M. Wilson,
Mohamed Ismail Sahib,
K. T. M. Ahmed Ibrahim,
Mahboob Ali Baig Sahib Bahadur,
B. Pocker Sahib Bahadur, pattam Tanupillai

text:
Bombay:
Balchandra Maheshwar Gupte,
Hansa Mehta,
Hari Vinayak Pataskar,
Dr. B. R. Ambedkar,
Joseph Alban D'Souza,
Kanayalal Nanabhai Desai,
Keshavrao Marutirao Jedhe,
Khandubhai Kasanji Desai,
Bal Gangadhar Kher,
M.R. Masani,
K.M. Munshi,
Narahar Vishnu Gadgil,
S. Nijalingappa,
S. K. Patil,
Ramchandra Manohar Nalavade,
R. R. Diwakar,
Shankarrao Deo,
G. V. Mavalankar,
Vallabhbhai Patel,
Abdul Kadar Mohammad Shaikh,
A. A. Khan

text:
West Bengal:
Monomohan Das,
Arun Chandra Guha,
Lakshmi Kanta Maitra,
Mihir Lal Chattopadhyay,
Satis Chandra Samanta,
Suresh Chandra Majumdar,
Upendranath Barman,
Prabhudayal Himatsingka,
Basanta Kumar Das,
Renuka Ray,
H. C. Mukherjee,
Surendra Mohan Ghose,
Syama Prasad Mookerjee,
Ari Bahadur Gurung,
R. E. Platel,
K. C. Neogy,
Raghib Ahsan,
Somnath Lahiri,
Jasimuddin Ahmad,
Naziruddin Ahmad,
Abdul Hamid,
Abdul Halim Ghuznavi

text:
United Provinces:
Ajit Prasad Jain,
Algu Rai Shastri,
Balkrishna Sharma,
Banshi Dhar Misra,
Bhagwan Din,
Damodar Swarup Seth,
Dayal Das Bhagat,
Dharam Prakash,
A. Dharam Dass,
R. V. Dhulekar,
Feroz Gandhi,
Gopal Narain,
Krishna Chandra Sharma,
Govind Ballabh Pant,
Govind Malviya,
Har Govind Pant,
Harihar Nath Shastri,
Hriday Nath Kunzru,
Jaspat Roy Kapoor,
Jagannath Baksh Singh,
Jawaharlal Nehru,
Jogendra Singh,
Jugal Kishore,
Jwala Prasad Srivastava,
B. V. Keskar,
Kamala Chaudhry,
Kamalapati Tripathi,
J. B. Kripalani,
Mahavir Tyagi,
Khurshed Lal,
Masurya Din,
Mohan Lal Saksena,
Padampat Singhania,
Phool Singh,
Paragi Lal,
Purnima Banerjee,
Purushottam Das Tandon,
Hira Vallabha Tripathi,
Ram Chandra Gupta,
Shibban Lal Saxena,
Satish Chandra,
John Matthai,
Sucheta Kripalani,
Sunder Lall,
Venkatesh Narayan Tiwari,
Mohanlal Gautam,
Vishwambhar Dayal Tripathi,
Vishnu Sharan Dublish,
Begum Aizaz Rasul,
Hyder Hussain,
Hasrat Mohani,
Abul Kalam Azad,
Muhammad Ismail Khan,
Rafi Ahmad Kidwai,
Mohd. Hifzur Rahman,
Z H Lari

text:
East Punjab:
Bakshi Tek Chand,
Jairamdas Daulatram,
Thakurdas Bhargava,
Bikramlal Sondhi,
Yashwant Rai,
Ranbir Singh Hooda,
Lala Achint Ram,
Nand Lal,
Baldev Singh,
Giani Gurmukh Singh Musafir,
Sardar Hukam Singh,
Sardar Bhopinder Singh Mann,
Sardar Rattan Singh Lohgarh
Chaudhry Suraj Mal

text:
Bihar:
Nasif Arafat,
Amiyo Kumar Ghosh,
Anugrah Narayan Sinha,
Banarsi Prasad Jhunjhunwala,
Bhagwat Prasad,
Boniface Lakra,
Brajeshwar Prasad,
Chandika Ram,
K. T. Shah,
Devendra Nath Samanta,
Dip Narain Sinha,
Guptanath Singh,
Jadubans Sahay,
Jagat Narain Lal,
Jagjivan Ram,
Jaipal Singh Munda,
Kameshwar Singh of Darbhanga,
Kamaleshwari Prasad Yadav,
Mahesh Prasad Sinha,
Krishna Ballabh Sahay,
Raghunandan Prasad,
Rajendra Prasad,
Rameshwar Prasad Sinha,
Ramnarayan Singh,
Sachchidananda Sinha,
Sarangdhar Sinha,
Satyanarayan Sinha,
Binodanand Jha,
P. K. Sen,
Sri Krishna Sinha,
Sri Narayan Mahtha,
Syamanandan Mishra,
Hussain Imam,
Syed Jafar Imam,
Latifur Rahman,
Mohammad Tahir,
Tajamul Hussain,
Choudhry Abid Hussain.
Hargovind Mishra

text:
Central Provinces and Berar:
Ambica Charan Shukla,
Raghu Vira,
Rajkumari Amrit Kaur,
B.A. Mandloi,
Brijlal Nandlal Biyani,
Thakur Cheedilal,
Seth Govind Das,
Hari Singh Gour,
Hari Vishnu Kamath,
Hemchandra Jagobaji Khandekar,
Ghanshyam Singh Gupta,
Lakshman Shrawan Bhatkar,
Panjabrao Shamrao Deshmukh,
Ravi Shankar Shukla,
R. K. Sidhva,
Shankar Trimbak Dharmadhikari,
Frank Anthony,
Kazi Syed Karimuddin,
Ganpatrao Dani

text:
Assam:
Nibaran Chandra Laskar,
Dharanidhar Basu-Matari,
Gopinath Bardoloi,
J. J. M. Nichols-Roy,
Kuladhar Chaliha,
Rohini Kumar Chaudhury,
Muhammad Saadulla,
Abdur Rouf

text:
Orissa:
Biswanath Das,
Krishna Chandra Gajapati Narayana Dev,
Harekrushna Mahatab,
Laxminarayan Sahu
Lokanath Mishra,
Nandkishore Das,
Rajkrishna Bose,
Santanu Kumar Das,
Yudhishir Mishra

text:
Delhi:
Deshbhandhu Gupta

text:
Ajmer-Merwara:
Mukut Bihari Lal Bhargava

text:
Coorg:
C. M. Poonacha

text:
Mysore:
K.C. Reddy,
T. Siddalingaiya,
H. R. Guruv Reddy,
S. V. Krishnamurthy Rao,
K. Hanumanthaiya,
H. Siddaveerappa,
T. Channiah

text:
Jammu and Kashmir:
Sheikh Muhammad Abdullah,
Motiram Baigra,
Mirza Mohammad Afzal Beg,
Maulana Mohammad Sayeed Masoodi

text:
Travancore-Cochin:
Pattom A. Thanu Pillai,
R. Sankar,
P. T. Chacko,
Panampilly Govinda Menon,
Annie Mascarene,
P.S.Nataraja Pillai,
K.A. Mohamed

text:
Madhya Bharat:
Vinayak Sitaram Sarwate,
Brijraj Narain,
Gopikrishna Vijayavargiya,
Ram Sahai,
Kusum Kant Jain,
Radhavallabh Vijayavargiya,
Sitaram S. Jajoo

text:
Saurashtra:
Balwant Rai Gopalji Mehta,
Jaisukhlal Hathi,
Amritlal Vithaldas Thakkar,
Chimanlal Chakubhai Shah,
Samaldas Laxmidas Gandhi

text:
Rajasthan:
V. T. Krishnamachari,
Hiralal Shastri,
Sardar Singhjhi of Khetri,
Jaswant Singhji,
Raj Bhadur,
Manikya Lal Varma,
Gokul Lal Asava,
Ramchandra Upadhyaya,
Balwant Sinha Mehta,
Dalel Singh,
Jainarain Vyas

text:
Patiala and East Punjab States Union:
Ranjit Singh,
Sochet Singh,
Bhagwant Roy

text:
Bombay States:
Vinayakrao Balshankar Vaidya,
B. N. Munavalli,
Gokulbhai Daulatram Bhatt,
Jivraj Narayan Mehta,
Gopaldas A. Desai,
Paranlal Thakurlal Munshi,
B. H. Khardekar,
Ratnappa Bharamappa Kumbhar

text:
Orissa States:
Lal Mohan Pati,
N. Madhava Rau,
Raj Kunwar,
Sarangadhar Das,
Yudhishthir Mishra

text:
Central Provinces States:
R. L. Malaviya,
Kishorimohan Tripathi,
Ramprasad Potai

text:
United Provinces States:
B. H. Zaidi,
Krishna Singh

text:
Madras States:
V. Ramaiah,
Ramakrishna Ranga Rao

text:
Vindhya Pradesh:
Avdesh Pratap Singh,
Shambu Nath Shukla,
Ram Sahai Tiwari,
Mannulalji Dwidedi

text:
Cooch Behar:
Himmat Singh K. Maheshwari

text:
Tripura and Manipur:
Girja Shankar Guha

text:
Bhopal:
Lal Singh

text:
Kutch:
Bhawani Arjun Khimji

text:
Himachal Pradesh:
Yashwant Singh Parmar

text: Members who later withdrew after partition[edit]

text:
East Bengal:
Abdullah al Mahmood,
Maulana Mohd Abdullah el Baqui,
Abdul Hamid,
Abdul Kasem Khan,
Mohammad Akram Khan,
A. Hamid,
Azizuddin Ahmad,
Muhammad Habibullah Bahar,
Prem Hari Barma,
Raj Kumar Chakraverty,
Sris Chandra Chattopadhyaya,
Abdul Matin Chaudhary,
Murtaza Raza Choudhry,
Hamidul Haq Chowdhury,
Akhay Kumar Das,
Dhirendra Nath Datta,
Bhupendra Kumar Datta,
Ebrahim Khan,
Fazlul Huq,
Fazlur Rahman,
Ghayasuddin Pathan,
Begum Shaista Suhrawardy Ikramullah,
Liaquat Ali Khan,
Mafizuddin Ahmad,
Mahmud Hussain,
Jnanendra Chandra Majumdar,
A. M. Malik,
Birat Chandra Mandal,
Jogendra Nath Mandal,
Mohammed Ali,
Khwaja Nazimuddin,
M.A.B.L. Nur Ahmed,
Nurul Amin,
Ishtiaq Hussain Qureshi,
Sri Dhananjoy M.A. B.L. Roy,
Maudi Bhakesh Chanda,
B.L. Serajul Islam,
Maulana Shabbir Ahmad Osmani,
Shahabudin Khwaja,
H.S. Suhrawardy,
Harendra Kumar Sur,
Tamizuddin Khan,
Kawivi Kerwar Datta,
Ghulam Mohammed

text:
West Punjab:
Mian Mumtaz Mohammad Khan Daultana,
Ganga Saran,
Zafarullah Khan,
Iftikhar Hussain Khan,
Mian Muhammad Iftikharuddin,
Muhammad Ali Jinnah,
Sheikh Karamat Ali,
Nazir Ahmad Khan,
Sardar Abdur Rab Nistar,
Feroz Khan Noon,
Omar Hayat Malik,
Shah Nawaz Begum Jahan Ara,
Sardar Shaukat Hyat Khan,

text:
Northwest Frontier Province:
Khan Abdul Ghafar Khan,
Khan Sardar Bahadur Khan,
Sardar Asad Ullah Jan Khan

text:
Sindh:
Abdus Sattar Abdur Rahman,
Alhajj Muhammad Hashim Gazder,
M.A. Khuhro

text:
Balochistan:
S. B. Nawab Mohammad Khan Jogezai

text: Gallery[edit]

text:
Jawaharlal Nehru and other members taking pledge during the midnight session of the Constituent Assembly of India held on 14 and 15 August 1947.

Dr. Babasaheb Ambedkar Chairman, Drafting Committee of the Indian Constitution with other members on Aug. 29, 1947.

Dr. Babasaheb Ambedkar, chairman of the Drafting Committee, presenting the final draft of the Indian Constitution to Dr. Rajendra Prasad on 25 November, 1949.

B. R. Ambedkar in Constituent Assembly of India.

Jawaharlal Nehru addressing the constituent assembly in 1946.


document_title: Cabinet of Malawi

question_text: who is the minister of agriculture in malawi

text: Cabinet of Malawi

text: This article needs to be updated. Please update this article to reflect recent events or newly available information. (May 2017)

text:
Malawi

This article is part of a series on the
politics and government of
Malawi

Constitution[show]

Human rights

Government[show]

President (list)

Peter Mutharika

Vice-President

Saulos Chilima

Cabinet

Legislature[show]

National Assembly

Speaker: Richard Msowoya

Elections[show]

General

1964 1971 1976 1978 1983 1987 1992 1994 1999 2004 2009 2014

Referendums

1993

Political parties

Administrative divisions[show]

Regions
Districts

Foreign relations[show]

Minister of Foreign Affairs
Diplomatic missions

of Malawi
to Malawi

Passport

Visa requirements

National symbols[show]

Flag
Anthem

Other countries
Atlas

v
t
e

text: The Cabinet of Malawi is the executive branch of the government, made up of the President, Vice President, Ministers and Deputy Ministers responsible for the different departments.[1]

text: Current Cabinet[edit]

text:
Party key

Democratic Progressive Party

United Democratic Front

text:
Cabinet of Malawi: June 2014 – Present[2]

Portrait
Portfolio
Incumbent
Term began

President
Minister of Defence
Commander-in-chief of the Armed and Police forces

H.E. Peter Mutharika
31 May 2014 –

Vice President
Minister for Civil Service

Rt. Hon. Saulos Chilima
31 May 2014 –

Minister of Agriculture and Irrigation

Hon. Allan Chiyembekeza MP
19 June 2014 –

Minister of Education, Science and Technology

Hon. Emmanuel Fabiano MP
19 June 2014 –

Minister of Finance, Economic Planning and Development

Hon. Goodall Gondwe
06 June 2014 –

Minister of Foreign Affairs and International cooperation

Hon. George Chaponda MP
19 June 2014 –

Minister of Gender, Children, Disability and Social Welfare

Hon. Patricia Kaliati MP
23 June 2014 –

Minister of Health

Hon. Peter Kumpalume MP
19 June 2014 –

Minister of Home Affairs

Hon. Paul Chibingu MP
23 June 2014 –

Minister of Information, Tourism and Civic Education

Hon. Kondwani Nankhumwa MP
19 June 2014 –

Minister of Justice and Constitutional Affairs

Hon. Samuel Tembenu
19 June 2014 –

Minister of Labour

Hon. Henry Mussa MP
19 June 2014 –

Minister of Lands, Housing and Urban Development

Hon. Bright Msaka
23 June 2014 –

Minister of Local Government and Rural Development

Hon. Trasizio Gowelo MP
23 June 2014 –

Minister of Natural Resources, Energy and Mining

Hon. Atupele Muluzi MP
23 June 2014 –

Minister of Trade and Industry

Hon. Joseph Mwanamveka MP
23 June 2014 –

Minister of Transport and Public works

Hon. Francis Kasaila MP
19 June 2014 –

Minister of Youth, Sports and Culture

Hon. Grace Chiumia MP
19 June 2014 –

Deputy Ministers

Deputy Minister of Defence

Hon. Jappie Mhango MP
23 June 2014 –

Deputy Minister of Education Science and Technology

Hon. Vincent Ghambi MP
23 June 2014 –


document_title: Dew point

question_text: relative humidity calculation from dew point and temperature

text: Dew point

text: Humidity[edit]

text: Given that all the other factors influencing humidity remain constant, at ground level the relative humidity rises as the temperature falls. This is because less vapor is needed to saturate the air so, vapor condenses as the temperature falls. Dew point temperature is never greater than the air temperature because relative humidity cannot exceed 100%.[4]

text: In technical terms, the dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates.[5] At temperatures below the dew point, the rate of condensation will be greater than that of evaporation, forming more liquid water. The condensed water is called dew when it forms on a solid surface, or frost if it freezes. The condensed water is called either fog or a cloud, depending on its altitude, when it forms in the air.

text: A high relative humidity implies that the dew point is closer to the current air temperature. A relative humidity of 100% indicates the dew point is equal to the current temperature and that the air is maximally saturated with water. When the moisture content remains constant and temperature increases, relative humidity decreases.[6]

text: General aviation pilots use dew point data to calculate the likelihood of carburetor icing and fog, and to estimate the height of a cumuliform cloud base.

text: At a given temperature but independent of barometric pressure, the dew point is a consequence of the absolute humidity, the mass of water per unit volume of air. If both the temperature and pressure rise, however, the dew point will increase and the relative humidity will decrease accordingly. Reducing the absolute humidity without changing other variables will bring the dew point back down to its initial value. In the same way, increasing the absolute humidity after a temperature drop brings the dew point back down to its initial level. If the temperature rises in conditions of constant pressure, then the dew point will remain constant but the relative humidity will drop. For this reason, a constant relative humidity with different temperatures implies that when it is hotter, a higher fraction of the air is present as water vapor compared to when it is cooler.

text: At a given barometric pressure but independent of temperature, the dew point indicates the mole fraction of water vapor in the air, or, put differently, determines the specific humidity of the air. If the pressure rises without changing this mole fraction, the dew point will rise accordingly. Reducing the mole fraction, i.e., making the air less humid, would bring the dew point back down to its initial value. In the same way, increasing the mole fraction after a pressure drop brings the relative humidity back up to its initial level. Considering New York (33 ft or 10 m elevation) and Denver (5,280 ft or 1,610 m elevation),[7] for example, this means that if the dew point and temperature in both cities are the same, then the mass of water vapor per cubic meter of air will be the same, but the mole fraction of water vapor in the air will be greater in Denver.

text: Relationship to human comfort[edit]

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text: When the air temperature is high, the human body uses the evaporation of sweat to cool down, with the cooling effect directly related to how fast the perspiration evaporates. The rate at which perspiration can evaporate depends on how much moisture is in the air and how much moisture the air can hold. If the air is already saturated with moisture, perspiration will not evaporate. The body's thermoregulation will produce perspiration in an effort to keep the body at its normal temperature even when the rate it is producing sweat exceeds the evaporation rate, so one can become coated with sweat on humid days even without generating additional body heat (such as by exercising).

text: As the air surrounding one's body is warmed by body heat, it will rise and be replaced with other air. If air is moved away from one's body with a natural breeze or a fan, sweat will evaporate faster, making perspiration more effective at cooling the body. The more unevaporated perspiration, the greater the discomfort.

text: A wet bulb thermometer also uses evaporative cooling, so it provides a good measure for use in evaluating comfort level.

text: Discomfort also exists when the dew point is low (below around −30 °C or −22 °F).[citation needed] The drier air can cause skin to crack and become irritated more easily. It will also dry out the airways. The US Occupational Safety and Health Administration recommends indoor air be maintained at 20–24.5 °C (68–76 °F) with a 20–60% relative humidity, equivalent to a dew point of −4.5 to 15.5 °C (24 to 60 °F).[citation needed]

text: Lower dew points, less than 10 °C or 50 °F, correlate with lower ambient temperatures and the body requires less cooling. A lower dew point can go along with a high temperature only at extremely low relative humidity, allowing for relatively effective cooling.

text: People inhabiting tropical and subtropical climates acclimatize somewhat to higher dew points. Thus, a resident of Darwin or Miami, for example, might have a higher threshold for discomfort than a resident of a temperate climate like London or Chicago. Those accustomed to temperate climates often begin to feel uncomfortable when the dew point reaches between 15 and 20 °C (59–68 °F), while others might find dew points below 18 °C (64 °F) comfortable. Most inhabitants of these areas will consider dew points above 21 °C or 70 °F oppressive and tropical-like.

text:
Dew point
Human perception[6]
Relative humidity at 32 °C (90 °F)

Over 26 °C
Over 80 °F
Severely high, even deadly for asthma related illnesses
73% and higher

24–26 °C
75–80 °F
Extremely uncomfortable, oppressive
62–72%

21–24 °C
70–74 °F
Very humid, quite uncomfortable
52–61%

18–21 °C
65–69 °F
Somewhat uncomfortable for most people at upper edge
44–51%

16–18 °C
60–64 °F
OK for most, but all perceive the humidity at upper edge
37–43%

13–16 °C
55–59 °F
Comfortable
31–36%

10–12 °C
50–54 °F
Very comfortable
26–30%

Under 10 °C
Under 50 °F
A bit dry for some
25% and lower

text: Measurement[edit]

text: Devices called hygrometers are used to measure dew point over a wide range of temperatures. These devices consist of a polished metal mirror which is cooled as air is passed over it. The temperature at which dew forms is, by definition, the dew point. Manual devices of this sort can be used to calibrate other types of humidity sensors, and automatic sensors may be used in a control loop with a humidifier or dehumidifier to control the dew point of the air in a building or in a smaller space for a manufacturing process.

text: Extreme values[edit]

text: A dew point of 33 °C (91 °F) was observed at 14:00 EDT on July 12, 1987, in Melbourne, Florida. A dew point of 32 °C (90 °F) has been observed in the United States on at least two other occasions: Appleton, Wisconsin, at 17:00 CDT on July 13, 1995, and New Orleans Naval Air Station at 17:00 CDT on July 30, 1987. A dew point of 35 °C (95 °F) was observed at Dhahran, Saudi Arabia, at 15:00 AST on July 8, 2003, which caused the heat index to reach 81 °C (178 °F), the highest value recorded.

text: Calculating the dew point[edit]

text: A well-known approximation used to calculate the dew point, Tdp, given just the actual ("dry bulb") air temperature, T (in degrees Celsius) and relative humidity (in percent), RH, is the Magnus formula:

text: The more complete formulation and origin of this approximation involves the interrelated saturated water vapor pressure (in units of millibars, also called hectopascals) at T, Ps(T), and the actual vapor pressure (also in units of millibars), Pa(T), which can be either found with RH or approximated with the barometric pressure (in millibars), BPmb, and "wet-bulb" temperature, Tw is (unless declared otherwise, all temperatures are expressed in degrees Celsius):

text: For greater accuracy, Ps(T) (and therefore γ(T, RH)) can be enhanced, using part of the Bögel modification, also known as the Arden Buck equation, which adds a fourth constant d:

text: where

text: There are several different constant sets in use. The ones used in NOAA's presentation[8] are taken from a 1980 paper by David Bolton in the Monthly Weather Review:[9]

text: These valuations provide a maximum error of 0.1%, for −30 °C ≤ T ≤ 35°C and 1% < RH < 100%. Also noteworthy is the Sonntag1990,[10]

text: Another common set of values originates from the 1974 Psychrometry and Psychrometric Charts, as presented by Paroscientific,[11]

text: Also, in the Journal of Applied Meteorology and Climatology,[12] Arden Buck presents several different valuation sets, with different minimum accuracies for different temperature ranges. Two particular sets provide a range of −40 °C to +50 °C between the two, with even greater minimum accuracy than all of the other, above sets (maximum error at extremes of temperature range):

text: Simple approximation[edit]

text: There is also a very simple approximation that allows conversion between the dew point, temperature, and relative humidity. This approach is accurate to within about ±1 °C as long as the relative humidity is above 50%:

text: This can be expressed as a simple rule of thumb:

text: For every 1 °C difference in the dew point and dry bulb temperatures, the relative humidity decreases by 5%, starting with RH = 100% when the dew point equals the dry bulb temperature.

text: The derivation of this approach, a discussion of its accuracy, comparisons to other approximations, and more information on the history and applications of the dew point are given in the Bulletin of the American Meteorological Society.[13]

text: For temperatures in degrees Fahrenheit, these approximations work out to

text: For example, a relative humidity of 100% means dew point is the same as air temp. For 90% RH, dew point is 3 °F lower than air temperature. For every 10 percent lower, dew point drops 3 °F.

text: Frost point[edit]

text: The frost point is similar to the dew point, in that it is the temperature to which a given parcel of humid air must be cooled, at constant barometric pressure, for water vapor to be deposited on a surface as ice without going through the liquid phase. (Compare with sublimation.) The frost point for a given parcel of air is always higher than the dew point, as the stronger bonding between water molecules on the surface of ice requires higher temperature to break.[14]