Audio

AM radio uses amplitude modulation, in which the amplitude of the transmitted signal is made proportional to the sound amplitude captured (transduced) by the microphone, while the transmitted frequency remains unchanged. Transmissions are affected by static and interference because lightning and other sources of radio emissions on the same frequency add their amplitudes to the original transmitted amplitude. In the early part of the 20th century, American AM radio stations broadcast with powers as high as 500 kW, and some could be heard worldwide; these stations' transmitters were commandeered for military use by the US Government during World War II. Currently, the maximum broadcast power for a civilian AM radio station in the United States and Canada is 50 kW, and the majority of stations that emit signals this powerful were grandfathered in (see List of 50kw AM radio stations in the USA). In 1986 KTNN received the last granted 50,000 watt license. These 50 kW stations are generally called "clear channel" stations (not to be confused with Clear Channel Communications), because within North America each of these stations has exclusive use of its broadcast frequency throughout part or all of the broadcast day.

Bush House, home of the BBC World Service.

FM broadcast radio sends music and voice with higher fidelity than AM radio. In frequency modulation, amplitude variation at the microphone causes the transmitter frequency to fluctuate. Because the audio signal modulates the frequency and not the amplitude, an FM signal is not subject to static and interference in the same way as AM signals. Due to its need for a wider bandwidth, FM is transmitted in the Very High Frequency (VHF, 30 MHz to 300 MHz) radio spectrum. VHF radio waves act more like light, traveling in straight lines; hence the reception range is generally limited to about 50–100 miles. During unusual upper atmospheric conditions, FM signals are occasionally reflected back towards the Earth by the ionosphere, resulting in long distance FM reception. FM receivers are subject to the capture effect, which causes the radio to only receive the strongest signal when multiple signals appear on the same frequency. FM receivers are relatively immune to lightning and spark interference.

High power is useful in penetrating buildings, diffracting around hills, and refracting in the dense atmosphere near the horizon for some distance beyond the horizon. Consequently, 100,000 watt FM stations can regularly be heard up to 100 miles (160 km) away, and farther (e.g., 150 miles, 240 km) if there are no competing signals. A few old, "grandfathered" stations do not conform to these power rules. WBCT-FM (93.7) in Grand Rapids, Michigan, USA, runs 320,000 watts ERP, and can increase to 500,000 watts ERP by the terms of its original license. Such a huge power level does not usually help to increase range as much as one might expect, because VHFfrequencies travel in nearly straight lines over the horizon and off into space. Nevertheless, when there were fewer FM stations competing, this station could be heard near Bloomington, Illinois, USA, almost 300 miles (500 km) away.^{[citation needed]}

FM subcarrier services are secondary signals transmitted in a "piggyback" fashion along with the main program. Special receivers are required to utilize these services. Analog channels may contain alternative programming, such as reading services for the blind, background music or stereo sound signals. In some extremely crowded metropolitan areas, the sub-channel program might be an alternate foreign language radio program for various ethnic groups. Sub-carriers can also transmit digital data, such as station identification, the current song's name, web addresses, or stock quotes. In some countries, FM radios automatically re-tune themselves to the same channel in a different district by using sub-bands.

Aviation voice radios use VHF AM. AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of weaker stations due to FM's capture effect). Aircraft fly high enough that their transmitters can be received hundreds of miles (or kilometres) away, even though they are using VHF.

Degen DE1103, an advanced world mini-receiver with single sideband modulation and dual conversion

Marine voice radios can use single sideband voice (SSB) in the shortwave High Frequency (HF—3 MHz to 30 MHz) radio spectrum for very long ranges or narrowband FM in the VHF spectrum for much shorter ranges. Narrowband FM sacrifices fidelity to make more channels available within the radio spectrum, by using a smaller range of radio frequencies, usually with five kHz of deviation, versus the 75 kHz used by commercial FM broadcasts, and 25 kHz used for TV sound.

Government, police, fire and commercial voice services also use narrowband FM on special frequencies. Early police radios used AM receivers to receive one-way dispatches.

Civil and military HF (high frequency) voice services use shortwave radio to contact ships at sea, aircraft and isolated settlements. Most use single sideband voice (SSB), which uses less bandwidth than AM. On an AM radio SSB sounds like ducks quacking, or the adults in a Charlie Brown cartoon. Viewed as a graph of frequency versus power, an AM signal shows power where the frequencies of the voice add and subtract with the main radio frequency. SSB cuts the bandwidth in half by suppressing the carrier and one of the sidebands. This also makes the transmitter about three times more powerful, because it doesn't need to transmit the unused carrier and sideband.

TETRA, Terrestrial Trunked Radio is a digital cell phone system for military, police and ambulances. Commercial services such as XM,WorldSpace and Sirius offer encrypted digital Satellite radio.

Uses of radio

Early uses were maritime, for sending telegraphic messages using Morse code between ships and land. The earliest users included the Japanese Navy scouting the Russian fleet during the Battle of Tsushima in 1905. One of the most memorable uses of marine telegraphy was during the sinking of the RMS Titanic in 1912, including communications between operators on the sinking ship and nearby vessels, and communications to shore stations listing the survivors.

Radio was used to pass on orders and communications between armies and navies on both sides in World War I; Germany used radio communications for diplomatic messages once it discovered that its submarine cables had been tapped by the British. The United States passed on President Woodrow Wilson's Fourteen Points to Germany via radio during the war. Broadcasting began from San Jose, Californiain 1909,^[17] and became feasible in the 1920s, with the widespread introduction of radio receivers, particularly in Europe and the United States. Besides broadcasting, point-to-point broadcasting, including telephone messages and relays of radio programs, became widespread in the 1920s and 1930s. Another use of radio in the pre-war years was the development of detection and locating of aircraft and ships by the use of radar (RAdio Detection And Ranging).

Today, radio takes many forms, including wireless networks and mobile communications of all types, as well as radio broadcasting. Before the advent of television, commercial radio broadcasts included not only news and music, but dramas, comedies, variety shows, and many other forms of entertainment (the era from 1930 to the mid-1950s is commonly called radio's "Golden Age"). Radio was unique among methods of dramatic presentation in that it used only sound. For more, see radio programming.

History Main article: History of radio

Many physicists, inventors, engineers, developers, and businessmen contributed to produce modern radio systems. The origins and 'invention' are multiple and controversial. Early radio designs could not transmit sound or speech and were called the "wireless telegraph".

Development from a laboratory demonstration to a commercial entity spanned several decades and required the efforts of many practitioners. In 1878, David E. Hughes noticed that sparks could be heard in a telephone receiver when experimenting with his carbon microphone. He developed this carbon-based detector further and eventually could detect signals over a few hundred yards. He demonstrated his discovery to the Royal Society in 1880, but was told it was merely induction, and therefore abandoned further research.

Tesla demonstrating wireless transmissions during his high frequency and potential lecture of 1891. After continued research, Tesla presented the fundamentals of radio in 1893.

In 1895, Guglielmo Marconi built a wireless system capable of transmitting signals at long distances (1.5 mi./ 2.4 km).^[3][4] In radio transmission technology, early public experimenters had made short distance broadcasts.^[5] Marconi achieved long range signalling due to a wireless transmitting apparatus and a radio receiver claimed by him.^[6][7] From Marconi's experiments, the phenomenon that transmission range is proportional to the square of antenna height is known as "Marconi's law".^[8] This formula represents a physical law that radio devices use. Marconi's experimental apparatus proved to be a complete, commercially successfulradio transmission system.^[7][9][10] According to the Proceedings of the United States Naval Institute in 1899, the Marconi instruments had a "[...] coherer, principle of which was discovered some twenty years ago, [and was] the only electrical instrument or device contained in the apparatus that is at all new".^[11]

Telephone Herald in Budapest, Hungary(1901).

In 1896, Marconi was awarded British patent 12039, Improvements in transmitting electrical impulses and signals and in apparatus there-for, for radio. In 1897, he established a radio station on the Isle of Wight, England. Marconi opened his "wireless" factory in Hall Street, Chelmsford, England in 1898, employing around 50 people. Shortly after the 1900s, Marconi held the patent rights for radio.

On Christmas Eve, 1906, Reginald Fessenden used a synchronous rotary-spark transmitter for the first AM radio program broadcast, from Ocean Bluff-Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible. This was, for all intents and purposes, the first transmission of what is now known as amplitude modulation or AM radio.

Radio broadcasting

The first radio news program was broadcast August 31, 1920 by station 8MK in Detroit, Michigan, which survives today as all-news format station WWJ under ownership of the CBS network. The first college radio station began broadcasting on October 14, 1920, from Union College, Schenectady, New York under the personal call letters of Wendell King, an African-American student at the school.^[12] That month 2ADD, later renamed WRUC in 1947, aired what is believed to be the first public entertainment broadcast in the United States, a series of Thursday night concerts initially heard within a 100-mile (160 km) radius and later for a 1,000-mile (1,600 km) radius. In November 1920, it aired the first broadcast of a sporting event.^[12][13] At 9 pm on August 27, 1920, Sociedad Radio Argentina aired a live performance of Richard Wagner's Parsifal opera from the Coliseo Theater in downtown Buenos Aires. Only about twenty homes in the city had receivers to tune in this radio program. Meanwhile, regular entertainment broadcasts commenced in 1922 from the Marconi Research Centre at Writtle, England.

Sports broadcasting began at this time as well, including the first broadcast college football game.^[14]

Patent rights after the 1900s.

American girl listens to radio during theGreat Depression.

One of the first developments in the early 20th century was that aircraft used commercial AM radio stations for navigation. This continued until the early 1960s when VOR systems became widespread.^[15] In the early 1930s, single sideband andfrequency modulation were invented by amateur radio operators. By the end of the decade, they were established commercial modes. Radio was used to transmit pictures visible as television as early as the 1920s. Commercial television transmissions started in North America and Europe in the 1940s.

In 1954, the Regency company introduced a pocket transistor radio, the TR-1, powered by a "standard 22.5 V Battery". In 1955, the newly formed Sony company introduced its first transistorized radio.^[16] It was small enough to fit in a vest pocket, and able to be powered by a small battery. It was durable, because it had no vacuum tubes to burn out. Over the next 20 years, transistors replaced tubes almost completely except for very high-power transmitter uses. By 1963, color television was being regularly broadcast commercially (though not all broadcasts or programs were in color), and the first (radio) communication satellite, Telstar, was launched. In the late 1960s, the U.S. long-distance telephone network began to convert to a digital network, employing digital radios for many of its links. In the 1970s, LORAN became the premier radio navigation system. Soon, the U.S. Navy experimented with satellite navigation, culminating in the invention and launch of the GPS constellation in 1987. In the early 1990s, amateur radioexperimenters began to use personal computers with audio cards to process radio signals. In 1994, the U.S. Army and DARPA launched an aggressive, successful project to construct asoftware-defined radio that can be programmed to be virtually any radio by changing its software program. Digital transmissions began to be applied to broadcasting in the late 1990s.

एसएलसीको मार्कसिट ढिला आउने

असार, काठमाडौँ । प्रवेशिका परीक्षा एसएलसी परीक्षाको मार्कसिट केही ढिला गरी आउने भएको छ ।

परीक्षा नियन्त्रण कार्यालय सानोठिमीले मार्कसिट र प्रोभिजनल सर्टिफिकेट सँगै दिनुपर्ने भएकाले मार्कसिट आउन ढिलाई हुने जनाएको छ । परीक्षाफल प्रकाशित भएको मितीले १५ दिनभित्र मार्कसिट र प्रोभिजनल सँगै दिने तयारीमा परीक्षा नियन्त्रण कार्यालय लागेको छ ।

नेपालमा एसएलसी परीक्षा सुरु भएको ७६ वर्षपछि परीक्षा नियन्त्रण कार्यालयले यस वर्षदेखि पहिलोपटक एसएलसी परीक्षामा उत्तीर्ण विद्यार्थीलाई ‘मार्कसीट’सँगै मूल प्रमाणपत्र दिन लागेको हो ।

यसअघि परीक्षाफल प्रकाशित भएको लामो समयसम्म पनि विद्यार्थीले मूल प्रमाणपत्र पाउन नसकेको गुनासो बढेपछि ‘मार्कसीट’सँगै प्रोभिजनल सर्टिफिकेट पनि दिन लागिएको परीक्षा नियन्त्रक सूर्यप्रसाद गौतमले जानकारी दिनुभयो ।

‘एक्समेन-फस्ट क्लास’ कलाकारको भूतसँग जम्काभेट

निर्माणाधिन हलिउड फिल्म ‘एक्समेन-फस्ट क्लास’ का कलाकारहरुले शुटिङ्का क्रममा भूतले तर्साएको बताएका छन् । सन ८०० ताका बनेको बेलायतको बर्क्ससायरस्थित एजन्लफिल्ड नामक महलमा ६ हप्ते लामो बसाइका क्रममा भूतहरुसँग रात विताउनु परेको उनीहरुले खुलासा गरेका छन् । हरेक रात भूतहरु घरभित्र ओहोरदोहोर गर्ने गरेको उनीहरुले अनुभव साटे ।

‘राती धेरै भूतहरु महलभित्र यताउता हिडडुल गर्दथे,’ फिल्मका नायक जेम्स मिकाभोएले एक कहालीलाग्दो रात सम्झदै भने, ‘मसँग वास्तवमै भेट भएको भूत सर प्याटि्रक स्टेवार्ड थियो । जसको भूमिका म फिल्म म खेलिरहेको छु ।’ अचम्म लाग्दो कुरा के छ भने फिल्ममा स्टेवार्डको भूमिका नराम्रो गरेकोले भूतले स्कटिस नायक जेम्सलाई तर्साएको स्रोतले बताएको छ ।

देवता र भूतको अस्तित्वमा विश्वास नगर्ने नास्तिक ब्यक्तिहरुलाई भने यो घटनाबारे विश्वास गर्न गाहृै छ । यो घटना कतै फिल्म प्रचार गर्ने नौलो तरिका त हैन ?

मिल्ने भन्दा भाँड्ने कसरतमा दलहरु

समाचार टिप्पणी । तीन महिना संविधानसभाको म्याद थपेर फुर्सदिला भएका दल र नेताहरुका पछिल्ला गतिबिधिले मुलुकलाई ठ्याक्कै जेठ १४ अघिकै स्थितिमा फर्काएको छ ।

संविधानसभाको म्याद थप्दा भएको पाँचबुँदे सहमति कार्यान्वयनमा दलहरुले सिन्कै भाँचेनन् भनौं भने संविधानको मस्यौदा र सेना समायोजनको कार्यतालिका तयार भएको छ । हैन काम भयो, अब त पक्कै केही गर्ने भए भनौं भने शान्ति र संविधानको मेलोमा हलो जहाँ अड्केको थियो, त्यही बिन्दूमा छ । अड्केको हलो झिकेर मेलो सार्न फेरि पनि दलहरुका अडान, अभिव्यक्ति र असहिष्णु व्यवहार नै बाधक बनेका छन् ।

शीर्ष नेताहरुले तयार पारेको कार्यतालिमा मुख्य दलका नेताहरुकै असहमति छ । कांग्रेसका नेताहरु संविधानभन्दा पहिले शान्ति प्रकृया टुंग्याउनुपर्ने बताउँछन् । माओवादीको एक खेमा संविधानको मस्यौदा तयार भएपछि मात्र शान्ति प्रकृया टुंग्याउनपर्ने अडानमा छ । यस्तै राष्ट्रिय सहमतिको सरकार बन्ने साईत र प्रकृया के भन्नेमा सबै अन्योलमा छन् । सहमतिको आधारबारे सबैका आआफ्नै शर्त, स्वार्थ र अडान छन् । जेठ १४ अघि जस्तो अवस्था थियो, त्यसमा खासै परिवर्तन आएको छैन । न नेताहरुका भाषण परिवर्तन भएका छन्, न व्यवहार र कार्यशैली । एकअर्कालाई आरोपप्रत्यारोप गर्ने उनीहरुका पुरानो बानी सुधार हुन नसक्दा फेरि पनि अलमल र अन्योल बढाएको छ ।

सहमतीय राजनीतिको टड्कारो खाँचो रहेको वर्तमान अवस्थामा विमतीको खाडल झन्झन् बढ्दैछ । जुन कुरा केही नेताहरुका पछिल्ला अभिव्यक्तिबाट थाहा हुन्छ । विशेष समितिले सेना समायोजनको काम अघि बढाईरहेको बेला रक्षामन्त्री विष्णु पौडेलले सेनाको समूहगत प्रवेश हुन सक्दैन भनेर विवाद बढाउने काम गरे । कांग्रेसका नेताहरु त झन् माओवादी र उसका सेनाप्रति बढी नै आक्रोशित देखिन्छन् । शीर्ष नेताहरुको दोहोरो सुरक्षा हटाएर माओवादीले सकारात्मक कदम अगाडि बढाईरहेको बेला कांग्रेस नेताहरु अब उसलाई निशस्त्रीकरण नै गर्नुपर्ने अभिव्यक्ति दिईरहेका छन् । भदौ १४ सम्म शान्ति प्रकृया टुंग्याउने सहमतिमा कांग्रेसले आफैं हस्ताक्षर गरेको छ, अनि त्यो अघि नै सहमतिको सरकार बन्नुपर्ने उसकै माग छ । सहमतीय सरकार बनाउँदा त्यसमा माओवादी पनि अट्नुपर्छ । तर माओवादी पूर्ण रुपमा निशस्त्र नहुँदासम्म सरकारमा जान हुँदैन भनेर कांग्रेसले अड्डी लिएको लियै छ ।

अहिल्यै सहमतिको सरकार पनि बन्नुपर्ने, माओवादी पनि निशस्त्र हुनुपर्ने हो भने शान्ति प्रकृयाको लागि भदौ १४ सम्म किन पर्खनुपथ्र्यो ? आफ्ना तर्कमा परस्पर विरोधी कुरा छन् भन्ने जान्दाजान्दै पनि कांग्रेस नेताहरुले पुरानो रटान लगाउन छाडेका छैनन् । अनि भदौ १४ सम्म जसरी भएपनि संविधानको मस्यौदा र शान्ति प्रकृया टुंग्याउने काममा लाग्छौं भन्नुपर्नेमा कांग्रेसले सबैलाई उछिन्ने गरी आन्दोलन गर्छौं भनेर निर्णय गरिसक्यो ।

माओवादीको खोईरो खन्न एमालेका नेताहरु पनि कम छैनन् । केही दिनअघि मात्रै बरिष्ठ नेता माधवकुमार नेपालले शान्ति प्रकृयामा माओवादी ईमान्दार नभएको र उसको पुच्छर बनेर हिंड्न नहुने भन्दै रीस पोखे । जसले माओवादी नेताहरुलाई आक्रोशित बनाउने काम मात्रै गर्यो ।

समस्या माओवादीभित्र पनि चर्को छ । सहमतिको वातावरण नबन्दासम्म खनाल नेतृत्वको सरकारले राजिनामा दिन हुन्न भनेर पार्टी नेतृत्वले भनिरहेको बेला माओवादी उपाध्यक्ष डाक्टर बाबुराम भट्टराई, नेता देवेन्द्र पौडेल लगायतका नेताहरु राजिनामा दिनुपर्छ भन्दै हिंडिरहेका छन् । सेना समायोजन, राष्ट्रिय सहमतिको सरकार र संविधानका अन्तर्वस्तुबारे माओवादीका नेतापिच्छेका फरक कुरा छन् । अरु दललाई मात्रै होईन, माओवादीका एक खेमा आफ्नै नेतृत्वको कुरा काट्दै हिंडिरहेका छन् । दोहोरो सुरक्षा हटाउने पार्टी निर्णयलाई वैद्य पक्षले नोट अफ डिसेन्ट मात्रै लेखेन, अटेर नै गरेर जित्यो ।

दलहरुबीच सहमतिको वातावरण निर्माण गर्नुपर्ने बेला माओवादी नेताहरु आफ्नै पार्टीभित्र एकअर्का बिरुद्ध खोईरो खन्न व्यस्त छन् । संविधानसभाको म्याद थप्ने बेला भएको सहमति अनुसार भदौ १४ सम्म संविधानको मस्यौदा र शान्ति प्रकृया टुंग्याउन संविधानसभामा प्रतिनिधित्व गर्ने सबै दल त्यसमा पनि माओवादी, कांग्रेस र एमाले एक ठाउँमा उभिनैपर्छ ।

उनीहरुबीच सहमति नजुट्दासम्म न संविधानको मेलो अघि सर्छ, न शान्ति प्रकृयाको । यो कुरा आम मानिसलाई मात्र होईन, यी तीनवटै दलका नेताहरुलाई पनि राम्रोसँग थाहा छ । तर घुमिफिरी रुम्जाटार भनेजस्तै तीन दल अझै तीनतिर फर्केर बाँसुरी बजाउनमै मग्न छन् ।

ऐश्वर्या गर्भवति

ऐश्वर्या राय बच्चनलाई अहिले आमा बन्न लागेको खुसी एकातिर छ भने गर्भवती भएको कुरा सार्वजनिक होला कि भन्ने अर्को ठूलो चिन्ता छ । केहि समयअघि एक कार्यक्रमको सिलसिलामा फ्रान्समा रहँदा ऐश्वर्या आफ्नो प्रेग्नेन्सीलाई लुकाउन लुज फिटिङको पहिरनमा देखापरेकी थिइन् ।

यति मात्र हो र, ऐश्वर्याले हरेक पटक फोटोग्राफरसामू तस्विर खिचाउँदा आफ्नो बढ्दो पेटलाई हात वा कपडाले छोपेको प्रष्ट देखिन्थ्यो । आखिर उनी के लुकाउन खोज्दै छिन् ? उनको यस्तो अनौठो ब्यवहारले उनी गर्भवती भएको हल्ला सहि ठहरिएको बलिउड उद्योगमा चर्चा चलेको छ ।

फ्रान्सबाट घर फर्केपछि एक सार्वजनिक कार्यक्रममा आफ्नी आमा बृन्दासँग उपस्थित हुँदा पनि ऐश्वर्याले सारीको एक छेउको मदत लिई पेटलाई छापेकी थिइन् ।

आफ्नो आगामी फिल्म ‘हिरोइन’ को छायांकनमा ब्यस्त रहेकी ऐश्वर्य गर्भवती हुने सोचमा नभएकै कारण पनि उनले यस्तो गरेको हुन सक्ने धेरैले अड्कल काटेका छन् ।

ऐश्वर्य वा उनको बच्चन परिवारबाट आधिकारिक धारणा सार्वजनिक नभएसम्म उनी साँच्चै गर्भवती हुन वा होइनन्, यो निर्क्योल गर्न कठिन छ ।

त्यतिजेलसम्म तपाई ऐश्वर्यले चनाखोपूर्वक पेट लुकाएको तस्विर हेरी अडकलबाजी गर्न सक्नुहुनेछ । के यी तस्विरहरुमा ऐश्वर्यले फुच्चे बच्चनलाई लुकाउने प्रयास गरेकी हुन त ?  तस्वीरः एजेन्सी