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108-508: IBOC relies on unused areas of the existing spectrum to send its signals. This is particularly useful in North America style FM, where channels are widely spaced at 200 kHz but use only about 50 kHz of that bandwidth for the audio signal. In most countries, FM channel spacing may be as close as 100 kHz, and on AM it is only 10 kHz. While these all offer some room for additional digital broadcasts, most attention on IBOC

216-451: A phase reversal or phase inversion implies a 180-degree phase shift. When the phase difference φ ( t ) {\displaystyle \varphi (t)} is a quarter of turn (a right angle, +90° = π/2 or −90° = 270° = −π/2 = 3π/2 ), sinusoidal signals are sometimes said to be in quadrature , e.g., in-phase and quadrature components of a composite signal or even different signals (e.g., voltage and current). If

324-924: A simple harmonic oscillation or sinusoidal signal is the value of φ {\textstyle \varphi } in the following functions: x ( t ) = A cos ⁡ ( 2 π f t + φ ) y ( t ) = A sin ⁡ ( 2 π f t + φ ) = A cos ⁡ ( 2 π f t + φ − π 2 ) {\displaystyle {\begin{aligned}x(t)&=A\cos(2\pi ft+\varphi )\\y(t)&=A\sin(2\pi ft+\varphi )=A\cos \left(2\pi ft+\varphi -{\tfrac {\pi }{2}}\right)\end{aligned}}} where A {\textstyle A} , f {\textstyle f} , and φ {\textstyle \varphi } are constant parameters called

432-419: A transition band the gain is not specified. In this case, the filter bandwidth corresponds to the passband width, which in this example is the 1 dB-bandwidth. If the filter shows amplitude ripple within the passband, the x  dB point refers to the point where the gain is x  dB below the nominal passband gain rather than x  dB below the maximum gain. In signal processing and control theory

540-733: A comprehensive trial of HD Radio technology in December 2006. The aim of the trial was to assess the coverage potential of the HD Radio system and to make a recommendation on the suitability of the technology for adoption. The first HD Radio station in the Philippines began broadcasting on November 9, 2005. The Philippines National Telecommunications Commission finalized its rules for FM digital radio operations on November 11, 2007. An HD Radio trial began in Warsaw in 2006 in order to demonstrate

648-400: A cycle. This concept can be visualized by imagining a clock with a hand that turns at constant speed, making a full turn every T {\displaystyle T} seconds, and is pointing straight up at time t 0 {\displaystyle t_{0}} . The phase φ ( t ) {\displaystyle \varphi (t)} is then the angle from

756-455: A digital signal where the C-QUAM system would put the analog stereo decoding information. Digital Radio Mondiale has had much more success in creating an AM system, and one that could be much less expensive to implement than any proprietary HD Radio system, although it requires new frequency. It is the only one to have been accepted mediumwave but also shortwave (and possibly longwave ) by

864-507: A full period. This convention is especially appropriate for a sinusoidal function, since its value at any argument t {\displaystyle t} then can be expressed as φ ( t ) {\displaystyle \varphi (t)} , the sine of the phase, multiplied by some factor (the amplitude of the sinusoid). (The cosine may be used instead of sine, depending on where one considers each period to start.) Usually, whole turns are ignored when expressing

972-411: A full turn: φ = 2 π [ [ τ T ] ] . {\displaystyle \varphi =2\pi \left[\!\!\left[{\frac {\tau }{T}}\right]\!\!\right].} If F {\displaystyle F} is a "canonical" representative for a class of signals, like sin ⁡ ( t ) {\displaystyle \sin(t)}

1080-837: A higher bitrate in Sirius satellite radio, see Digital Audio Radio Service ), but in August 2003 a switch to HDC (based-upon ACC) was made to rectify these problems. HDC has been customized for IBOC, and it is also likely that the patent rights and royalties for every transmitter and receiver can be retained longer by creating a more proprietary system. Digital Radio Mondiale is also developing an IBOC system, likely to be used worldwide with AM shortwave radio, and possibly with broadcast AM and FM. Neither of those have been approved yet for ITU region 2 (the Americas). Both AM and FM IBOC signals cause interference to adjacent-channel stations, but not within

1188-421: A microphone. This is usually the case in linear systems, when the superposition principle holds. For arguments t {\displaystyle t} when the phase difference is zero, the two signals will have the same sign and will be reinforcing each other. One says that constructive interference is occurring. At arguments t {\displaystyle t} when the phases are different,

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1296-417: A periodic soundwave recorded by two microphones at separate locations. Or, conversely, they may be periodic soundwaves created by two separate speakers from the same electrical signal, and recorded by a single microphone. They may be a radio signal that reaches the receiving antenna in a straight line, and a copy of it that was reflected off a large building nearby. A well-known example of phase difference

1404-431: A shifted and possibly scaled version G {\displaystyle G} of it. That is, suppose that G ( t ) = α F ( t + τ ) {\displaystyle G(t)=\alpha \,F(t+\tau )} for some constants α , τ {\displaystyle \alpha ,\tau } and all t {\displaystyle t} . Suppose also that

1512-503: A shifted version G {\displaystyle G} of it. If the shift in t {\displaystyle t} is expressed as a fraction of the period, and then scaled to an angle φ {\displaystyle \varphi } spanning a whole turn, one gets the phase shift , phase offset , or phase difference of G {\displaystyle G} relative to F {\displaystyle F} . If F {\displaystyle F}

1620-423: A sonic phase difference occurs in the warble of a Native American flute . The amplitude of different harmonic components of same long-held note on the flute come into dominance at different points in the phase cycle. The phase difference between the different harmonics can be observed on a spectrogram of the sound of a warbling flute. Phase comparison is a comparison of the phase of two waveforms, usually of

1728-435: A system of frequency response H ( f ) {\displaystyle H(f)} is the bandwidth of an ideal filter with rectangular frequency response centered on the system's central frequency that produces the same average power outgoing H ( f ) {\displaystyle H(f)} when both systems are excited with a white noise source. The value of the noise equivalent bandwidth depends on

1836-408: A transmitter that multiplexes them all into one ensemble with the same coverage area (though many FM stations are already diplexed in large cities such as New York). [1] A further concern to FM station operators was that AM stations could suddenly be in competition with the same high audio quality, although FM would still have the advantage of higher data rates (300 kbit/s versus 60 kbit/s in

1944-495: Is a "canonical" function for a class of signals, like sin ⁡ ( t ) {\displaystyle \sin(t)} is for all sinusoidal signals, then φ {\displaystyle \varphi } is called the initial phase of G {\displaystyle G} . Let the signal F {\displaystyle F} be a periodic function of one real variable, and T {\displaystyle T} be its period (that is,

2052-581: Is a "canonical" function of a phase angle in 0 to 2π, that describes just one cycle of that waveform; and A {\displaystyle A} is a scaling factor for the amplitude. (This claim assumes that the starting time t 0 {\displaystyle t_{0}} chosen to compute the phase of F {\displaystyle F} corresponds to argument 0 of w {\displaystyle w} .) Since phases are angles, any whole full turns should usually be ignored when performing arithmetic operations on them. That is,

2160-528: Is a function of an angle, defined only for a single full turn, that describes the variation of F {\displaystyle F} as t {\displaystyle t} ranges over a single period. In fact, every periodic signal F {\displaystyle F} with a specific waveform can be expressed as F ( t ) = A w ( φ ( t ) ) {\displaystyle F(t)=A\,w(\varphi (t))} where w {\displaystyle w}

2268-631: Is a less meaningful measure in wideband applications. A percent bandwidth of 100% corresponds to a ratio bandwidth of 3:1. All higher ratios up to infinity are compressed into the range 100–200%. Ratio bandwidth is often expressed in octaves (i.e., as a frequency level ) for wideband applications. An octave is a frequency ratio of 2:1 leading to this expression for the number of octaves, log 2 ⁡ ( B R ) . {\displaystyle \log _{2}\left(B_{\mathrm {R} }\right).} The noise equivalent bandwidth (or equivalent noise bandwidth (enbw) ) of

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2376-440: Is also used in spectral width , and more generally for the extent of functions as full width at half maximum (FWHM). In electronic filter design, a filter specification may require that within the filter passband , the gain is nominally 0 dB with a small variation, for example within the ±1 dB interval. In the stopband (s), the required attenuation in decibels is above a certain level, for example >100 dB. In

2484-458: Is also used to denote system bandwidth , for example in filter or communication channel systems. To say that a system has a certain bandwidth means that the system can process signals with that range of frequencies, or that the system reduces the bandwidth of a white noise input to that bandwidth. The 3 dB bandwidth of an electronic filter or communication channel is the part of the system's frequency response that lies within 3 dB of

2592-965: Is currently testing HD Radio in Beijing in contemplation for acceptance in that country. Caracol Radio began testing of the HD Radio technology in both the AM and FM bands in early 2008. El Salvador will be choosing HD Radio as its digital radio standard. In September 2007 the European HD Radio Alliance (EHDRA) was formed by broadcasters and other interested groups to promote the adoption of HD Radio technology by European broadcasters, regulators and standards organizations. France began broadcasting an HD Radio signal in March 2006 and plans to multicast two or more channels. The radio stations that use IBOC HD in France are SIRTI and NRJ Group. The owner of

2700-449: Is defined as the ratio of the upper and lower limits of the band, B R = f H f L . {\displaystyle B_{\mathrm {R} }={\frac {f_{\mathrm {H} }}{f_{\mathrm {L} }}}\,.} Ratio bandwidth may be notated as B R : 1 {\displaystyle B_{\mathrm {R} }:1} . The relationship between ratio bandwidth and fractional bandwidth

2808-514: Is defined the same way, except with "360°" in place of "2π". With any of the above definitions, the phase φ ( t ) {\displaystyle \varphi (t)} of a periodic signal is periodic too, with the same period T {\displaystyle T} : φ ( t + T ) = φ ( t )  for all  t . {\displaystyle \varphi (t+T)=\varphi (t)\quad \quad {\text{ for all }}t.} The phase

2916-631: Is either identically zero, or is a sinusoidal signal with the same period and phase, whose amplitude is the difference of the original amplitudes. The phase shift of the co-sine function relative to the sine function is +90°. It follows that, for two sinusoidal signals F {\displaystyle F} and G {\displaystyle G} with same frequency and amplitudes A {\displaystyle A} and B {\displaystyle B} , and G {\displaystyle G} has phase shift +90° relative to F {\displaystyle F} ,

3024-428: Is equal to the upper cutoff frequency of a low-pass filter or baseband signal, which includes a zero frequency. Bandwidth in hertz is a central concept in many fields, including electronics , information theory , digital communications , radio communications , signal processing , and spectroscopy and is one of the determinants of the capacity of a given communication channel . A key characteristic of bandwidth

3132-828: Is far less expensive and less complicated to implement, needing only to be plugged into the existing exciter , and requiring no licensing fees. FMeXtra has generally all the user features of HD Radio, including multicast capability, the ability to broadcast several different audio programs simultaneously. It uses the aacPlus (HE-AAC) codec. FMeXtra can restrict listening with conditional access and encryption . Digital Radio Mondiale allows for simultaneous transmission of multiple data streams alongside an audio signal. The DRM mode for VHF provides bandwidths from between 35 kbit/s to 185 kbit/s and up to four simultaneous data streams, allowing 5.1 surround DVD quality audio to be broadcast alongside other multimedia content - images, video or HTML content are typical examples. While it

3240-410: Is for all sinusoidal signals, then the phase shift φ {\displaystyle \varphi } called simply the initial phase of G {\displaystyle G} . Therefore, when two periodic signals have the same frequency, they are always in phase, or always out of phase. Physically, this situation commonly occurs, for many reasons. For example, the two signals may be

3348-490: Is given by, B F = 2 B R − 1 B R + 1 {\displaystyle B_{\mathrm {F} }=2{\frac {B_{\mathrm {R} }-1}{B_{\mathrm {R} }+1}}} and B R = 2 + B F 2 − B F . {\displaystyle B_{\mathrm {R} }={\frac {2+B_{\mathrm {F} }}{2-B_{\mathrm {F} }}}\,.} Percent bandwidth

In-band on-channel - Misplaced Pages Continue

3456-408: Is half its maximum value (or the spectral amplitude, in V {\displaystyle \mathrm {V} } or V / H z {\displaystyle \mathrm {V/{\sqrt {Hz}}} } , is 70.7% of its maximum). This figure, with a lower threshold value, can be used in calculations of the lowest sampling rate that will satisfy the sampling theorem . The bandwidth

3564-718: Is in the FM band in North American systems; in Europe and many other countries, entirely new bands were allocated for all-digital systems. Digital radio standards generally allow multiple program channels to be multiplexed into a single digital stream. In North American FM, this normally allows two or three high-fidelity signals combined in one channel, or one high-fidelity signal plus several additional channels at medium-fidelity levels that are much higher quality than AM. For even greater capacity, some existing subcarriers can be taken off

3672-592: Is inconsequentially larger. For wideband applications they diverge substantially with the arithmetic mean version approaching 2 in the limit and the geometric mean version approaching infinity. Fractional bandwidth is sometimes expressed as a percentage of the center frequency ( percent bandwidth , % B {\displaystyle \%B} ), % B F = 100 Δ f f C . {\displaystyle \%B_{\mathrm {F} }=100{\frac {\Delta f}{f_{\mathrm {C} }}}\,.} Ratio bandwidth

3780-422: Is not backwards compatible with existing FM receiver equipment, with broadcasts digitally encoded using HE-AAC or xHE-AAC , this ability to operate within the internationally agreed FM spectrum of 88-108 MHz makes DRM a viable candidate for future adoption if countries begin to eliminate their analog broadcasts. iBiquity also created a mediumwave HD Radio system for AM, which is the only system approved by

3888-679: Is now widespread in dense urban markets like Toronto , Vancouver and Ottawa , with some use on the AM band as well. Initial testing of the HD Radio system commenced in Prague in February 2007. In China, Hunan Broadcasting Company started FMeXtra transmissions in Changsha in April 2007, and plans to put others throughout the Hunan province. SARFT (State Administration for Radio, Film and Television)

3996-412: Is occupied by TV channels 7 to 13 and the amateur radio 1.25 meter (222 MHz) band. The stations currently occupying that spectrum did not wish to give up their space, since VHF offers several benefits over UHF: relatively lower power, long distance propagation (up to 100 miles (160 km) with a rooftop antenna), and a longer wavelength that is more robust and less affected by interference. In Canada,

4104-459: Is often quoted relative to the frequency of operation which gives a better indication of the structure and sophistication needed for the circuit or device under consideration. There are two different measures of relative bandwidth in common use: fractional bandwidth ( B F {\displaystyle B_{\mathrm {F} }} ) and ratio bandwidth ( B R {\displaystyle B_{\mathrm {R} }} ). In

4212-411: Is that any band of a given width can carry the same amount of information , regardless of where that band is located in the frequency spectrum . For example, a 3 kHz band can carry a telephone conversation whether that band is at baseband (as in a POTS telephone line) or modulated to some higher frequency. However, wide bandwidths are easier to obtain and process at higher frequencies because

4320-402: Is the test frequency , and the bottom sine signal represents a signal from the reference. If the two frequencies were exactly the same, their phase relationship would not change and both would appear to be stationary on the oscilloscope display. Since the two frequencies are not exactly the same, the reference appears to be stationary and the test signal moves. By measuring the rate of motion of

4428-415: Is the difference between the upper and lower frequencies in a continuous band of frequencies . It is typically measured in unit of hertz (symbol Hz). It may refer more specifically to two subcategories: Passband bandwidth is the difference between the upper and lower cutoff frequencies of, for example, a band-pass filter , a communication channel , or a signal spectrum . Baseband bandwidth

In-band on-channel - Misplaced Pages Continue

4536-400: Is the length of shadows seen at different points of Earth. To a first approximation, if F ( t ) {\displaystyle F(t)} is the length seen at time t {\displaystyle t} at one spot, and G {\displaystyle G} is the length seen at the same time at a longitude 30° west of that point, then the phase difference between

4644-487: Is the most widely used system, with approximately 1,560 stations transmitting HD radio in the US, plus over 800 new multicast channels (as of Jan 2010). There is a one-time license fee to iBiquity Digital, for the use of its intellectual property, as well as costs for new equipment which range from $ 50,000 to $ 100,000 US (2010) per station. The other system is FMeXtra by Digital Radio Express, which instead uses subcarriers within

4752-551: Is the only digital technology approved by the FCC for digital AM and FM broadcasting in the US. Over 60 different HD Radio receivers are on sale in over 12,000 stores nationwide, including Apple, Best Buy, Target, and Wal-Mart. As of May 2007, FMeXtra is on several dozen stations. Several hundred stations belonging to the Idea Bank consortium will also have FMeXtra installed. [2] Bandwidth (signal processing) Bandwidth

4860-480: Is the total bandwidth (i.e. the maximum passband bandwidth of the carrier-modulated RF signal and the minimum passband bandwidth of the physical passband channel), and W {\displaystyle W} is the positive bandwidth (the baseband bandwidth of the equivalent channel model). For instance, the baseband model of the signal would require a low-pass filter with cutoff frequency of at least W {\displaystyle W} to stay intact, and

4968-620: Is usually defined as the arithmetic mean of the upper and lower frequencies so that, f C = f H + f L 2   {\displaystyle f_{\mathrm {C} }={\frac {f_{\mathrm {H} }+f_{\mathrm {L} }}{2}}\ } and B F = 2 ( f H − f L ) f H + f L . {\displaystyle B_{\mathrm {F} }={\frac {2(f_{\mathrm {H} }-f_{\mathrm {L} })}{f_{\mathrm {H} }+f_{\mathrm {L} }}}\,.} However,

5076-772: Is zero at the start of each period; that is φ ( t 0 + k T ) = 0  for any integer  k . {\displaystyle \varphi (t_{0}+kT)=0\quad \quad {\text{ for any integer }}k.} Moreover, for any given choice of the origin t 0 {\displaystyle t_{0}} , the value of the signal F {\displaystyle F} for any argument t {\displaystyle t} depends only on its phase at t {\displaystyle t} . Namely, one can write F ( t ) = f ( φ ( t ) ) {\displaystyle F(t)=f(\varphi (t))} , where f {\displaystyle f}

5184-569: The Canadian Radio-Television and Telecommunications Commission (CRTC) and Canadian Broadcasting Corporation (CBC) have also looked at the use of HD Radio, given its gradual progress in the neighbouring U.S. The CBC began HD Radio testing in September 2006, focusing on transmissions from Toronto and Peterborough, Ontario . The CRTC has since revised its policy on digital radio to allow HD Radio operations. Use of HD Radio

5292-628: The International Telecommunication Union (ITU) for use in regions I and III, but not yet in region II, the Americas . The HD Radio system has also been approved by International Telecommunication Union. CAM-D is yet another method, though it is more of an extension of the current system. Developed by AM stereo pioneer Leonard R. Kahn , It encodes the treble on very small digital sidebands which do not cause interference to adjacent channels, and mixes it back with

5400-463: The equivalent baseband frequency response for H ( f ) {\displaystyle H(f)} . The noise equivalent bandwidth is widely used to simplify the analysis of telecommunication systems in the presence of noise. In photonics , the term bandwidth carries a variety of meanings: A related concept is the spectral linewidth of the radiation emitted by excited atoms. Quadrature phase In physics and mathematics ,

5508-399: The phase (symbol φ or ϕ) of a wave or other periodic function F {\displaystyle F} of some real variable t {\displaystyle t} (such as time) is an angle -like quantity representing the fraction of the cycle covered up to t {\displaystyle t} . It is expressed in such a scale that it varies by one full turn as

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5616-560: The § Fractional bandwidth is smaller. Bandwidth is a key concept in many telecommunications applications. In radio communications, for example, bandwidth is the frequency range occupied by a modulated carrier signal . An FM radio receiver's tuner spans a limited range of frequencies. A government agency (such as the Federal Communications Commission in the United States) may apportion

5724-434: The 12:00 position to the current position of the hand, at time t {\displaystyle t} , measured clockwise . The phase concept is most useful when the origin t 0 {\displaystyle t_{0}} is chosen based on features of F {\displaystyle F} . For example, for a sinusoid, a convenient choice is any t {\displaystyle t} where

5832-650: The Canadian Radio-television and Telecommunications Commission (CRTC) is continuing to follow the analog standard, so the channels remain unavailable there as well. HD Radio testing has been authorized in Canada, as well as other countries around the world. There was also concern that AM and FM stations' branding, using their current frequencies, would be lost to new channel numbers, though virtual channels such as on digital television would eliminate this. Also, several competing stations would have to share

5940-598: The Eureka-147 standard called DAB+ has been implemented. Using the more efficient high quality MPEG-4 CODEC HE-AAC v2, this compression method allows the DAB+ system to carry more channels or have better sound quality at the same bit rate as the original DAB system. It is the DAB+ implementation which will be under consideration for new station designs and not the earlier DAB scheme using the MUSICAM CODEC. The DAB+ system

6048-585: The Federal Communications Commission for digital AM broadcasting in the United States. The HD Radio system employs use of injected digital sidebands above and below the audible portion of the analog audio on the primary carrier. This system also phase modulates the carrier in quadrature and injects more digital information on this phase-modulated portion of the carrier. It is based on the principle of AM stereo where it puts

6156-493: The HD Radio standard) due to greater bandwidth (100 kHz versus 10 kHz). The most significant advantage for IBOC is its relative ease of implementation. Existing analog radios are not rendered obsolete and the consumer and industry may transition to digital at a rational pace. In addition, the technology infrastructure is in place: most major broadcast equipment manufacturers are implementing IBOC technology and 60+ receiver manufacturers are selling IBOC reception devices. In

6264-663: The National Metrology Institute (Inmetro) was done and the Digital Radio Consultative Council concluded that HD Radio and DRM do not meet the same analog transmission coverage with 20db less power. New trials are expected to occur before any decision about the Brazilian Digital Radio standard. Brazil is considering for adoption Digital Radio Mondiale or HD Radio. After having L-band DAB for several years,

6372-579: The U.S. FCC increase the permissible FM IBOC power from 1% (currently) to a maximum of 10% of the analog power. On January 29, 2010, the FCC approved the request. In addition, tropospheric ducting and e-skip can reduce the range of the digital signal, as well as the analog. IBOC digital radios using iBiquity's standard are being marketed under the brand "HD Radio" to highlight the purported quality of reception. As of June 2008, over 60 different receiver models have been made, and stations have received blanket (no longer individual and experimental) authorization from

6480-470: The U.S. FCC to transmit in a multiplexed multichannel mode on FM. Originally, the use of HD Radio transmission on AM was limited to daytime only, and not allowed at night due to potential problems with skywave radio propagation. The FCC lifted this restriction in early 2007. DRM, however, is being used across Europe on shortwave, which is entirely AM skywave, without issue. With the proper receiver, many of those stations can be heard in North America as well, sans

6588-536: The UK, Denmark, Norway and Switzerland, which are the leading countries with regard to implementing DAB, the first-generation MPEG-1 Audio Layer II (MP2) codec stereo radio stations on DAB have a lower sound-quality than FM, prompting a number of complaints. The typical bandwidth for DAB programs is only 128 kbit/s using the first generation CODEC, the less-robust MP2 standard which requires at least double that rate to be considered near-CD quality. An updated version of

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6696-687: The US. Grupo Imagen commenced HD Radio transmissions on XHDL-FM and XEDA-FM as well as Instituto Mexicano de la Radio on XHIMR-FM, XHIMER-FM and XHOF-FM in Mexico City in June 2012. HD Radio transmission in Auckland, New Zealand was started on October 19, 2005. The frequency of IBOC HD radio is 106.1 MHz. The transmitter is located at Skytower. Following successful testing, the Radio Broadcasters Association (RBA) initiated

6804-555: The United Kingdom and many other countries have chosen the Eureka 147 standard of digital audio broadcasting (DAB) for creating a digital radio service, the United States has selected IBOC technology for its digital AM and FM stations. The band commonly used for terrestrial DAB is part of VHF band III, which does not suffer from L-band's significant line-of-sight problems. However, it is not available in North America since that span

6912-561: The air to provide additional bandwidth in the modulation baseband . On FM for instance, this might mean removing stereo from the analog signal, relying on the digital signal to provide stereo where desired, thus making room for another digital channel. Due to the reduced bandwidth in AM, IBOC is incompatible with analog stereo, although that is rarely implemented, and additional channels are limited to highly compressed voice such as traffic and weather . Eventually, stations can go from digital/analog-hybrid mode to all-digital, by eliminating

7020-506: The analog baseband. Unlike the other two, it is not intended to be capable of multichannel, opting for quality over quantity. Unlike the HD system iBiquity calls "hybrid digital" the CAM-D system truly is a direct hybrid of both analog and digital. Some engineers believe that CAM-D may be compatible with analog AM stereo with the right engineering. Critics of CAM-D point to several drawbacks: While

7128-647: The analog signal. HD Radio technology was tested in 2004 with initial trials in Buenos Aires. Further testing of the technology began in early 2007. Government broadcaster BETAR began broadcasting HD Radio on their 100.0 MHz frequency on 9 November 2016 from their Agargaon site in Dhaka. The transmission uses a 10 kW GatesAir system. The 100.0 MHz carries programs from BBC World Service amongst others. HD 1, 2, 3 and 4 are configured. A second transmission will also have HD radio added on 88.8 MHz from

7236-583: The bandwidth is the frequency at which the closed-loop system gain drops 3 dB below peak. In communication systems, in calculations of the Shannon–Hartley channel capacity , bandwidth refers to the 3 dB-bandwidth. In calculations of the maximum symbol rate , the Nyquist sampling rate , and maximum bit rate according to the Hartley's law , the bandwidth refers to the frequency range within which

7344-571: The baseband monophonic audio. On FM there are three methods of IBOC broadcasting in use, primarily in the United States . The first, and only, digital technology approved for use on AM and FM broadcast frequencies by the Federal Communications Commission in the United States, is the proprietary HD Radio system developed by iBiquity Digital Corporation, which transmits energy beyond the allotted ±100 kHz FM channel. This creates potential interference issues with adjacent channels. This

7452-744: The broadcasts, more than 10,000 HD Radio receivers were installed in buses. The first FM HD Radio broadcasts in Kyiv went on the air in October 2006 on two FM stations operated by the First Ukrainian Radio Group. Voice of Vietnam (VOV) commenced AM and FM HD Radio transmissions in Hanoi in June, 2008 including multicasting, in anticipation of making HD Radio technology a standard. As of June 2008, more than 1,700 HD Radio stations were broadcasting 2,432 HD Radio channels. HD Radio technology

7560-585: The center frequency is sometimes defined as the geometric mean of the upper and lower frequencies, f C = f H f L {\displaystyle f_{\mathrm {C} }={\sqrt {f_{\mathrm {H} }f_{\mathrm {L} }}}} and B F = f H − f L f H f L . {\displaystyle B_{\mathrm {F} }={\frac {f_{\mathrm {H} }-f_{\mathrm {L} }}{\sqrt {f_{\mathrm {H} }f_{\mathrm {L} }}}}\,.} While

7668-414: The clock analogy, each signal is represented by a hand (or pointer) of the same clock, both turning at constant but possibly different speeds. The phase difference is then the angle between the two hands, measured clockwise. The phase difference is particularly important when two signals are added together by a physical process, such as two periodic sound waves emitted by two sources and recorded together by

7776-419: The clock analogy, this situation corresponds to the two hands turning at the same speed, so that the angle between them is constant. In this case, the phase shift is simply the argument shift τ {\displaystyle \tau } , expressed as a fraction of the common period T {\displaystyle T} (in terms of the modulo operation ) of the two signals and then scaled to

7884-402: The context of Nyquist symbol rate or Shannon-Hartley channel capacity for communication systems it refers to passband bandwidth. The Rayleigh bandwidth of a simple radar pulse is defined as the inverse of its duration. For example, a one-microsecond pulse has a Rayleigh bandwidth of one megahertz. The essential bandwidth is defined as the portion of a signal spectrum in

7992-416: The difference between them is a whole number of periods. The numeric value of the phase φ ( t ) {\displaystyle \varphi (t)} depends on the arbitrary choice of the start of each period, and on the interval of angles that each period is to be mapped to. The term "phase" is also used when comparing a periodic function F {\displaystyle F} with

8100-404: The existing signal. This system was introduced more recently. The FMeXtra is compatible with HD Radio in hybrid mode, but not in all-digital mode, and with RBDS . The stereo subcarrier can be removed to make more space available for FMeXtra in the modulation baseband. However, the system is not compatible with other existing 67–92 kHz subcarriers which have mostly fallen into disuse. The system

8208-404: The following, the absolute bandwidth is defined as follows, B = Δ f = f H − f L {\displaystyle B=\Delta f=f_{\mathrm {H} }-f_{\mathrm {L} }} where f H {\displaystyle f_{\mathrm {H} }} and f L {\displaystyle f_{\mathrm {L} }} are

8316-406: The fractional part of a real number, discarding its integer part; that is, [ [ x ] ] = x − ⌊ x ⌋ {\displaystyle [\![x]\!]=x-\left\lfloor x\right\rfloor \!\,} ; and t 0 {\displaystyle t_{0}} is an arbitrary "origin" value of the argument, that one considers to be the beginning of

8424-438: The frequencies are different, the phase difference φ ( t ) {\displaystyle \varphi (t)} increases linearly with the argument t {\displaystyle t} . The periodic changes from reinforcement and opposition cause a phenomenon called beating . The phase difference is especially important when comparing a periodic signal F {\displaystyle F} with

8532-470: The frequencies beyond which performance is degraded. In the case of frequency response , degradation could, for example, mean more than 3  dB below the maximum value or it could mean below a certain absolute value. As with any definition of the width of a function, many definitions are suitable for different purposes. In the context of, for example, the sampling theorem and Nyquist sampling rate , bandwidth typically refers to baseband bandwidth. In

8640-1279: The frequency domain using H ( f ) {\displaystyle H(f)} or in the time domain by exploiting the Parseval's theorem with the system impulse response h ( t ) {\displaystyle h(t)} . If H ( f ) {\displaystyle H(f)} is a lowpass system with zero central frequency and the filter reference gain is referred to this frequency, then: B n = ∫ − ∞ ∞ | H ( f ) | 2 d f 2 | H ( 0 ) | 2 = ∫ − ∞ ∞ | h ( t ) | 2 d t 2 | ∫ − ∞ ∞ h ( t ) d t | 2 . {\displaystyle B_{n}={\frac {\int _{-\infty }^{\infty }|H(f)|^{2}df}{2|H(0)|^{2}}}={\frac {\int _{-\infty }^{\infty }|h(t)|^{2}dt}{2\left|\int _{-\infty }^{\infty }h(t)dt\right|^{2}}}\,.} The same expression can be applied to bandpass systems by substituting

8748-463: The frequency domain which contains most of the energy of the signal. In some contexts, the signal bandwidth in hertz refers to the frequency range in which the signal's spectral density (in W/Hz or V /Hz) is nonzero or above a small threshold value. The threshold value is often defined relative to the maximum value, and is most commonly the 3 dB point , that is the point where the spectral density

8856-830: The function's value changes from zero to positive. The formula above gives the phase as an angle in radians between 0 and 2 π {\displaystyle 2\pi } . To get the phase as an angle between − π {\displaystyle -\pi } and + π {\displaystyle +\pi } , one uses instead φ ( t ) = 2 π ( [ [ t − t 0 T + 1 2 ] ] − 1 2 ) {\displaystyle \varphi (t)=2\pi \left(\left[\!\!\left[{\frac {t-t_{0}}{T}}+{\frac {1}{2}}\right]\!\!\right]-{\frac {1}{2}}\right)} The phase expressed in degrees (from 0° to 360°, or from −180° to +180°)

8964-428: The gain is non-zero. The fact that in equivalent baseband models of communication systems, the signal spectrum consists of both negative and positive frequencies, can lead to confusion about bandwidth since they are sometimes referred to only by the positive half, and one will occasionally see expressions such as B = 2 W {\displaystyle B=2W} , where B {\displaystyle B}

9072-406: The geometric mean is more rarely used than the arithmetic mean (and the latter can be assumed if not stated explicitly) the former is considered more mathematically rigorous. It more properly reflects the logarithmic relationship of fractional bandwidth with increasing frequency. For narrowband applications, there is only marginal difference between the two definitions. The geometric mean version

9180-418: The ideal filter reference gain used. Typically, this gain equals | H ( f ) | {\displaystyle |H(f)|} at its center frequency, but it can also equal the peak value of | H ( f ) | {\displaystyle |H(f)|} . The noise equivalent bandwidth B n {\displaystyle B_{n}} can be calculated in

9288-436: The origin for computing the phase of G {\displaystyle G} has been shifted too. In that case, the phase difference φ {\displaystyle \varphi } is a constant (independent of t {\displaystyle t} ), called the 'phase shift' or 'phase offset' of G {\displaystyle G} relative to F {\displaystyle F} . In

9396-731: The phase; so that φ ( t ) {\displaystyle \varphi (t)} is also a periodic function, with the same period as F {\displaystyle F} , that repeatedly scans the same range of angles as t {\displaystyle t} goes through each period. Then, F {\displaystyle F} is said to be "at the same phase" at two argument values t 1 {\displaystyle t_{1}} and t 2 {\displaystyle t_{2}} (that is, φ ( t 1 ) = φ ( t 2 ) {\displaystyle \varphi (t_{1})=\varphi (t_{2})} ) if

9504-478: The phases of two periodic signals F {\displaystyle F} and G {\displaystyle G} is called the phase difference or phase shift of G {\displaystyle G} relative to F {\displaystyle F} . At values of t {\displaystyle t} when the difference is zero, the two signals are said to be in phase; otherwise, they are out of phase with each other. In

9612-437: The physical passband channel would require a passband filter of at least B {\displaystyle B} to stay intact. The absolute bandwidth is not always the most appropriate or useful measure of bandwidth. For instance, in the field of antennas the difficulty of constructing an antenna to meet a specified absolute bandwidth is easier at a higher frequency than at a lower frequency. For this reason, bandwidth

9720-563: The purpose of discussing the rollout of the technology in Europe. Radio Sunshine has now switched to DAB+ due to the high penetration of DAB+ and lack of interest in HD Radio. DAB+ penetration in Switzerland has now reached 99.5% as of 2018. HD Radio transmission in Thailand was started in April 2006. Radio of Thailand had created a public IBOC HD radio network targeting mass transit commuters in Thailand's capital of Bangkok. To receive

9828-444: The regionally available bandwidth to broadcast license holders so that their signals do not mutually interfere. In this context, bandwidth is also known as channel spacing . For other applications, there are other definitions. One definition of bandwidth, for a system, could be the range of frequencies over which the system produces a specified level of performance. A less strict and more practically useful definition will refer to

9936-399: The response at its peak, which, in the passband filter case, is typically at or near its center frequency , and in the low-pass filter is at or near its cutoff frequency . If the maximum gain is 0 dB, the 3 dB bandwidth is the frequency range where attenuation is less than 3 dB. 3 dB attenuation is also where power is half its maximum. This same half-power gain convention

10044-417: The same nominal frequency. In time and frequency, the purpose of a phase comparison is generally to determine the frequency offset (difference between signal cycles) with respect to a reference. A phase comparison can be made by connecting two signals to a two-channel oscilloscope . The oscilloscope will display two sine signals, as shown in the graphic to the right. In the adjacent image, the top sine signal

10152-535: The same site. Trial and tests of HD Radio technology began in Sarajevo in March 2007. HD Radio and DRM trials in Brazil started in the mid 2000s. No regular HD Radio or DRM transmissions are allowed in Brazil as the digital radio standard in that country is not yet defined. One or two year experimental licenses were given to some Broadcasters. A joint study by the government (Ministry of Communications and ANATEL) and

10260-716: The smallest positive real number such that F ( t + T ) = F ( t ) {\displaystyle F(t+T)=F(t)} for all t {\displaystyle t} ). Then the phase of F {\displaystyle F} at any argument t {\displaystyle t} is φ ( t ) = 2 π [ [ t − t 0 T ] ] {\displaystyle \varphi (t)=2\pi \left[\!\!\left[{\frac {t-t_{0}}{T}}\right]\!\!\right]} Here [ [ ⋅ ] ] {\displaystyle [\![\,\cdot \,]\!]\!\,} denotes

10368-413: The station's interference-free protected contours designated by the U.S. Federal Communications Commission (FCC). It has led to derogatory terms such as IBAC (In-band adjacent-channel) and IBUZ (since the interference sounds like a buzz.) The range of a station on an HD Radio receiver is somewhat less than its analog signal. In June 2008, a group of US broadcasters and equipment manufacturers requested that

10476-740: The sum F + G {\displaystyle F+G} is a sinusoidal signal with the same frequency, with amplitude C {\displaystyle C} and phase shift − 90 ∘ < φ < + 90 ∘ {\displaystyle -90^{\circ }<\varphi <+90^{\circ }} from F {\displaystyle F} , such that C = A 2 + B 2  and  sin ⁡ ( φ ) = B / C . {\displaystyle C={\sqrt {A^{2}+B^{2}}}\quad \quad {\text{ and }}\quad \quad \sin(\varphi )=B/C.} A real-world example of

10584-567: The sum and difference of two phases (in degrees) should be computed by the formulas 360 [ [ α + β 360 ] ]  and  360 [ [ α − β 360 ] ] {\displaystyle 360\,\left[\!\!\left[{\frac {\alpha +\beta }{360}}\right]\!\!\right]\quad \quad {\text{ and }}\quad \quad 360\,\left[\!\!\left[{\frac {\alpha -\beta }{360}}\right]\!\!\right]} respectively. Thus, for example,

10692-533: The sum of phase angles 190° + 200° is 30° ( 190 + 200 = 390 , minus one full turn), and subtracting 50° from 30° gives a phase of 340° ( 30 − 50 = −20 , plus one full turn). Similar formulas hold for radians, with 2 π {\displaystyle 2\pi } instead of 360. The difference φ ( t ) = φ G ( t ) − φ F ( t ) {\displaystyle \varphi (t)=\varphi _{G}(t)-\varphi _{F}(t)} between

10800-648: The technology to local radio stations. WPRM FM is the first station in San Juan, Puerto Rico (part of the US) to adopt HD Radio, in April 2005. WRTU in San Juan has also commenced broadcasting in HD Radio technology in 2007. FM testing sponsored by Radio Sunshine and Ruoss AG began in Lucerne in April 2006. HD Radio operations in Switzerland continue and are spotlighted each year during “HD Radio Days”, an annual gathering in Lucerne of European broadcasters and manufacturers for

10908-401: The test signal the offset between frequencies can be determined. Vertical lines have been drawn through the points where each sine signal passes through zero. The bottom of the figure shows bars whose width represents the phase difference between the signals. In this case the phase difference is increasing, indicating that the test signal is lower in frequency than the reference. The phase of

11016-547: The transmitter is Towercast. The frequency of IBOC HD radio is 88.2 MHz. In May 2006, The Towercast group added a single channel of digital audio on 93.9 MHz. Radio Regenbogen began HD Radio operations on 102.8 MHz in Heidelberg on December 3, 2007 pursuant to government testing authority. Forum Radio Jaringan Indonesia had tested IBOC HD transmission from March 2006 to May 2006. The IBOC HD station in Jakarta

11124-441: The two signals will be 30° (assuming that, in each signal, each period starts when the shadow is shortest). For sinusoidal signals (and a few other waveforms, like square or symmetric triangular), a phase shift of 180° is equivalent to a phase shift of 0° with negation of the amplitude. When two signals with these waveforms, same period, and opposite phases are added together, the sum F + G {\displaystyle F+G}

11232-451: The upper and lower frequency limits respectively of the band in question. Fractional bandwidth is defined as the absolute bandwidth divided by the center frequency ( f C {\displaystyle f_{\mathrm {C} }} ), B F = Δ f f C . {\displaystyle B_{\mathrm {F} }={\frac {\Delta f}{f_{\mathrm {C} }}}\,.} The center frequency

11340-426: The value of the sum depends on the waveform. For sinusoidal signals, when the phase difference φ ( t ) {\displaystyle \varphi (t)} is 180° ( π {\displaystyle \pi } radians), one says that the phases are opposite , and that the signals are in antiphase . Then the signals have opposite signs, and destructive interference occurs. Conversely,

11448-427: The variable t {\displaystyle t} goes through each period (and F ( t ) {\displaystyle F(t)} goes through each complete cycle). It may be measured in any angular unit such as degrees or radians , thus increasing by 360° or 2 π {\displaystyle 2\pi } as the variable t {\displaystyle t} completes

11556-649: Was Delta FM (99.1 MHz). In April 2006, Radio Sangkakala (in Surabaya), the first AM HD radio station in Asia, went on the air on 1062 kHz. Radio Jamaica began operating full-time with both HD Radio AM and FM signals in the city of Kingston in 2008. All Mexican radio stations within 320 km of the U.S. border are allowed to transmit their programs on the AM and FM bands utilizing HD Radio technology. Approximately six Mexican AM and FM stations are already operating with HD Radio technology along Mexico’s border area with

11664-560: Was coordinated and developed by the World DAB Forum, formed in 1997 from the old organization. It gives the Eureka-147 system a similar quality per bit rate as the IBOC system and hence (arguably) a better sound quality than FM. AM IBOC in the United States still faces some serious technological challenges, including nighttime interference with other stations. iBiquity initially used an audio compression system known as PAC (also used at

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