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105-490: Several advantages of using digital voice modes are that it uses less bandwidth than older analog voice modes such as amplitude modulation and frequency modulation . The quality of the data received is also better than an analog signal at the same signal strength , as long as the signal is above a minimum threshold and as long as there is no multipath propagation . D-STAR compatible radios are available for HF , VHF , UHF , and microwave amateur radio bands. In addition to

210-419: 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

315-477: A Java-based APRS interface which is utilized on Gateway 2.0 systems to interface between the Icom/D-STAR GPS tracking system called DPRS to the more widely known and utilized amateur radio APRS system. Each participating amateur station wanting to use repeaters/gateways attached to a particular trust server domain must "register" with a gateway as their "home" system, which also populates their information into

420-638: A VHF downlink. In 2015, FlexRadio Systems added D-STAR support to their line of HF transceivers and receivers via a software upgrade. D-STAR support requires the addition of the ThumbDV device from NW Digital Radio. The system today is capable of linking repeaters together locally and through the Internet utilizing callsigns for routing of traffic. Servers are linked via TCP/IP utilizing proprietary "gateway" software, available from Icom. This allows amateur radio operators to talk to any other amateurs participating in

525-729: A computer. One group advocating the construction of home-brewed D-STAR repeaters is Free-Star. Free-Star is an experimental approach to the implementation of a vendor neutral, and open source, digital communication network for amateur radio. GB7LF in Lancaster, UK, went live in May 2009 and was a converted Tait repeater. It was preceded by two others in Weston-Super-Mare, UK and also another in Staffordshire, UK. [4] A Web-based text messaging application using D-STAR digital data technology. D-StarLet

630-622: A favorite mode is Mode "B" or "V/U" which simply indicates the uplink and downlink frequencies or bands the satellite is currently using. In this example, V/U means VHF/UHF or VHF uplink with UHF downlink. Most amateur satellites are Low Earth Orbit satellites, or LEO's as they are affectionately known, and generally are at about 450 miles (700 km) altitude. At that height, amateurs can expect reception distances of up to around 3,000 miles (4,800 km). A few amateur satellites have very high elliptical orbits. These satellites can reach altitudes of 30,000 miles (50,000 km) above

735-450: A form of encryption, and encryption is prohibited by almost every country's amateur radio licence conditions. According to FCC rules, if the algorithm is publicly published or otherwise widely available enough that transmissions are not secret, it is considered encoding rather than encryption. Unfortunately D-STAR uses AMBE, a non-public codec. However, French regulators, in April 2010, have issued

840-515: A full 10.x.x.x/8 network is required. From there, the Gateway has another NIC connected directly to the D-STAR repeater controller via 10BASE-T and the typical configuration is a 172.16.x.x (/24) pair of addresses between the gateway and the controller. The main differences between Gateway V1 and V2 are the addition of a relational database ( PostgreSQL ) for more flexibility and control of updates, versus

945-471: A handful of these "registered" IP addresses, because the system maps these to callsigns, and the callsign can be entered into multiple radios. The gateway machine controls two network interface controllers , the "external" one being on a real 10.x.x.x network behind a router. A router that can perform network address translation on a single public IP address (can be static or dynamic in Gateway G2 systems) to

1050-457: A lesser degree, in early winter. For receiving stations located within ± 10 degrees of the geomagnetic equator, equatorial E-skip can be expected on most days throughout the year, peaking around midday local time. By speeding up Morse code using analog tape or digital modes such as JT6M or FSK441 , very short high-speed bursts of digital data can be bounced off the ionized gas trail of meteor showers . The speed required to confirm

1155-423: A licensed amateur radio operator from possessing an amateur radio based on its factory ability to receive frequencies outside of ham bands. [ v ] All allocations are subject to variation by country. For simplicity, only common allocations found internationally are listed. See a band's article for specifics. [ w ] HF allocation created at the 1979 World Administrative Radio Conference . These are commonly called

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1260-419: A line-of-sight range of about 100 miles (160 km). Because it is local and reliable, and because the licensing requirements to transmit on the 2-meter band are easy to meet in many parts of the world, this band is one of the most popular non- HF ham bands. This popularity, the compact size of needed radios and antennas, and this band's ability to provide easy reliable local communications also means that it

1365-536: A local area on 10 GHz, which is valuable to allow emergency communications oriented networks to continue to link in the event of internet access failure or overload. Within the D-STAR Digital Voice protocol standards (DV), voice audio is encoded as a 3,600 bit/s data stream using proprietary AMBE encoding, with 1,200 bit/s FEC, leaving 1,200 bit/s for an additional data "path" between radios utilizing DV mode. On air bit rates for DV mode are 4,800 bit/s over

1470-410: A new request is transmitted. This continues until a reply is received to confirm the contact or until no contact can be made and no new requests are sent. Using this high speed digital mode, a full two way contact can be completed in one second or less and can only be validated using a computer. Depending on the intensity of the ionized meteor trail, multiple contacts from multiple stations can be made off

1575-575: A particular gateway "trust" environment. The current master gateway in the United States is operated by the K5TIT group in Texas, who were the first to install a D-STAR repeater system in the U.S. D-STAR transfers both voice and data via digital encoding over the 2 m (VHF), 70 cm (UHF), and 23 cm (1.3 GHz) amateur radio bands. There is also an interlinking radio system for creating links between systems in

1680-573: A pole or on the rooftop of a house or a vehicle. Even without repeaters available, however, the 2-meter band provides reliable crosstown communications throughout smaller towns, making it ideal for emergency communications. Antennas for repeater work are almost always vertically polarized since 2-meter antennas on cars are usually vertically polarized. Matching polarization allows for maximum signal coupling which equates to stronger signals in both directions. Simple radios for FM repeater operation have become plentiful and inexpensive in recent years. While

1785-456: A radio driving a power amplifier generating about 200–500 watts of RF power. This extra power is usually fed to a multi-element, compound antenna, usually a Yagi-Uda or Yagi , which can beam most of the signal power towards the intended receiving station. "Beam antennas" provide substantial increase in signal directivity over ordinary dipole or vertical antennas . Antennas used for distance work are usually horizontally polarized instead of

1890-535: A radio receiver and transmitter that instantly retransmits a received signal on a separate frequency. Repeaters are normally located in high locations such as a tall building or a hill top overlooking expanses of territory. On VHF frequencies such as 2-meters, antenna height greatly influences how far one can talk. Typical reliable repeater range is about 25 miles (40 km). Some repeaters in unusually high locations, such as skyscrapers or mountain tops, can be usable as far out as 75 miles (121 km). Reliable range

1995-426: A sporadic E event. A two-way conversation can take place over a distance of several hundred kilometers or more, often using low levels of RF power. Sporadic E is a rare and completely random propagation phenomenon lasting anywhere from a matter of minutes to several hours. Satellites are basically repeater stations in orbit. The 2 meter band is also used in conjunction with the 70-centimeter band , or

2100-464: A statement that rules D-STAR illegal in France, due to the ability to create a connection to the internet with it and the proprietary nature of the codec used. The French Amateur Radio society, DR@F - Digital Radioamateur France has an online petition against this ruling, calling for the government to allow the mode, as to ban it would deny them 'fundamental rights'. The world's first non-Icom D-Star repeater

2205-501: A swishing or whooshing noise. An exception to this phenomenon would be the 6 meter band which is significantly lower in frequency than the 2 meter band by 94 MHz. In many instances 6 meter voice modes are readable but with varying degrees of difficulty when reflected off an aurora. Therefore, when using an auroral event as a radio signal reflector, the reflected signal strength and signal intelligibility decreases with increasing transmitting frequency. To communicate over

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2310-435: 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

2415-408: A two way contact via a short lived ionized meteor trail can only be performed by fast computers on both ends with very little human interaction. One computer will send a request for contact and if successfully received by a distant station, a reply will be sent by the receiving stations computer usually via the same ionized meteor trail to confirm the contact. If nothing is received after the request,

2520-634: A wireless bridge via the RJ-45 Ethernet jack on the radios. It was the only radio to provide this function until the release of the IC-9700 in 2019. The first D-STAR satellite QSO occurred between Michael, N3UC, in Haymarket, Virginia and Robin, AA4RC, in Atlanta, Georgia while working AMSAT's AO-27 microsatellite ( Miniaturized satellite ) in 2007. The two experienced minor difficulty with doppler shift during

2625-511: Is JT65 which is a digital mode. Due to the delay of the signal traveling to the moon and back ( travel time approx. 2.5 seconds), a person transmitting may hear the end of their own transmission returning. The Irish Radio Transmitters Society has provided a series of awards for the first successful all-natural, non-bounce contacts on 2 metres between the North American and European continents. Named for Saint Brendan of Clonfert ,

2730-631: 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

2835-659: Is a portion of the VHF radio spectrum that comprises frequencies stretching from 144  MHz to 148 MHz in International Telecommunication Union region (ITU) Regions 2 (North and South America plus Hawaii) and 3 (Asia and Oceania) and from 144 MHz to 146 MHz in ITU Region 1 (Europe, Africa, and Russia). The license privileges of amateur radio operators include the use of frequencies within this band for telecommunication, usually conducted locally with

2940-478: Is also the most used band for local emergency communications efforts , such as providing communications between Red Cross shelters and local authorities. In the US, that role in emergency communications is furthered by the fact that many amateur-radio operators have a 2-meter handheld transceiver (HT), also known as a handie-talkie or walkie-talkie . Much of 2-meter FM operations use radio repeaters , which consist of

3045-440: 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

3150-458: 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

3255-411: Is an add-on tool that allows the overall system administrators to see the status of each Gateway's local clock and other processes and PIDs needed for normal system operation, and also sends traffic and other data to servers operated under the domain name of "dstarusers.org". By this means a complete tracking of user behaviour is technically possible. Installation of this software also includes JavaAPRSd,

D-STAR - Misplaced Pages Continue

3360-419: Is an open source client-server solution that allows content creation and modification from certain persons. D-StarLet interfaces with a D-STAR radio through the serial port. It works with Windows (98+), Linux (Red Hat 7.3+), Apple Mac OS X , and others. D-PRS is GPS for ham radio. Includes DStarTNC2, javAPRSSrvr, DStarInterface, and TNC-X A Java application run on the repeater gateway PC which logs activity on

3465-419: Is called Sporadic E propagation . This is a phenomenon whereby radio signals are reflected back towards Earth by highly ionized segments of the ionosphere which can facilitate contacts in excess of 1,000 miles (1,600 km) with very strong signals received by both parties. Unlike some other long distance modes, high power and large antennas are often not required to make contact with distant stations via

3570-449: 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

3675-490: 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

3780-408: 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

3885-592: 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

3990-459: 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

4095-526: Is one of the determinants of the capacity of a given communication channel . A key characteristic of bandwidth 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

4200-406: Is the ability to use callsign "suffixes" appended to the user's callsign in a similar fashion to the repeaters and gateways in the original system, which allow for direct routing to a particular user's radio or between two user radios with the same base callsign, by utilizing the 8th most significant field of the callsign and adding a letter to that location, both in the gateway registration process on

4305-480: 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

D-STAR - Misplaced Pages Continue

4410-620: 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,

4515-425: Is very dependent on the height of the repeater antenna and also on the height and surroundings of the handheld or mobile unit attempting to access to the repeater. Line of sight would be the ultimate in reliability. The typical hand held two meter FM transceiver produces about 5 watts of transmit power. Stations in a car or home might provide higher power, 25 to 75 watts, and may use a simple vertical antenna mounted on

4620-400: The 10-meter band and various microwave bands via orbiting amateur radio satellites . This is known as cross band repeating. On-board software defines what mode or band is in use at any particular time and this is determined by amateurs at so-called earth stations who control or instruct the satellite behavior. Amateurs know what mode is in use via published internet schedules. For instance,

4725-577: The International Space Station . Los Angeles County has a statute (which dates from 1944) concerning mounting a "shortwave receiver" in a motor vehicle. While the statute specifically states one of the forbidden bands as 150–160 MHz, most two-meter transceivers can tune into this portion of the spectrum at least as receivers, and are therefore unlawful to mount in a motor vehicle in Los Angeles County. While arrest rarely happens,

4830-458: 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. 2 meters The 2-meter amateur radio band

4935-540: 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

5040-467: The 2 m, 70 cm and 23 cm bands. In addition to digital voice mode (DV), a Digital Data (DD) mode can be sent at 128 kbit/s only on the 23 cm band. A higher-rate data protocol, currently believed to be much like ATM, is used in the 10 GHz "link" radios for site-to-site links. Radios providing DV data service within the low-speed voice protocol variant typically use an RS-232 or USB connection for low-speed data (1,200 bit/s), while

5145-514: The 2 meter band is best known as a local band using the FM mode, there are many opportunities for long distance (DX) communications using other modes. A well-placed antenna and high-power equipment can achieve distances of up to a few hundred miles, and fortuitous propagation conditions called "signal enhancements" can on occasion reach across oceans. The typical 2 meter station using CW ( Morse code ) or SSB (single side band) modes consists of

5250-417: The D-STAR branding. D-STAR, like any digital voice mode has comparable usable range to FM, but it degrades differently. While the quality of FM progressively degrades the further a user moves away from the source, digital voice maintains a constant voice quality up to a point, then essentially " falls off a cliff ". This behavior is inherent in any digital data system, and it demonstrates the threshold at which

5355-551: The DSL line installation, the repeater is connected to the Internet via a 3G dongle from network operator "Three". The system is built around Satoshi Yasuda's GMSK Node Adapter, a Mini-ITX system running CentOS 4, a Tait T800 repeater and G2 code written by G4ULF. All the usual G2 features such as callsign routing, D-Plus linkage and DPRS via D-STAR Monitor are supported. [1] [2] [3] Today a home-brewed D-STAR repeater can be built using open source software, used commercial radio equipment and

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5460-470: The Icom IC-V82. JARL released some changes to the existing D-STAR standard in late 2004. Icom, aware that the changes were coming, delayed the release of their hardware in anticipation of the changes. The Icom ID-1 1.3 GHz mobile radio was released in late 2004. The ID-1 was the first D-STAR radio that provided digital data (DD) mode operation. In this mode, data can be transferred at 128 kbit/s as

5565-466: The Icom ID-1 and IC-9700 radios offer a standard Ethernet connection for high-speed (128 kbit/s) connections on the 23 cm band. This allows easy interfacing with computer equipment. ‹The template How-to is being considered for merging .›   The current gateway control software rs-rp2c version G2, more commonly called "Gateway 2.0". Though most Linux distributions should be suitable,

5670-529: The QSO. As of late 2009, there are around 10,800 D-STAR users talking through D-STAR repeaters with Internet connectivity via the G2 Gateway. There are approximately 550 G2 enabled repeaters now active. Note, these numbers do not include users with D-STAR capabilities that are not within range of a repeater, or working through D-STAR repeaters that do not have Internet connectivity. The first D-STAR capable microsatellite

5775-454: The Web-based open-source tools from source for standardization purposes, while utilizing some of the packages of the host Linux system, thus making CentOS 5.1 the common way to deploy a system, to keep incompatibilities from occurring in both package versions and configuration. Additionally, gateways operating on the U.S. trust server are asked during initial setup to install DStarMonitor which

5880-477: The atmosphere and ionosphere that bend the signal path into an arc that better follows the curve of the Earth, instead of the radio waves traveling in the usual straight line off into space. The best known of these are: These and other well-known forms of VHF signal enhancement that allow trans-oceanic and trans-continental contacts on 2 meters are described in the subsections that follow within this section. With

5985-815: The atmosphere's troposphere known as tropospheric ducting can allow 2 meter signals to carry hundreds or even thousands of kilometers as evidenced by the occasional 2 meter contact between the west coast of the United States and the Hawaiian Islands, the northeast region to the Florida coast, and across the Gulf of Mexico. These so-called "Openings" are generally first spotted by amateurs operating SSB (Single Side Band) and CW (Continuous Wave) modes since amateurs using these modes typically are attempting distance contacts (DX) and alert for signal enhancement events. Completion of contacts using these weak signal modes involves

6090-413: The attached repeaters. Additional features include APRS object representation of each repeater. Bandwidth (signal processing) Bandwidth 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

6195-573: 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

6300-585: 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

6405-429: The constant movement of the ionized gas leads to heavy distortion of the signals causing the audio to sound "ghostly" and whispered. In most instances using auroral reflections on 2 meters, audio or voice is totally unintelligible and ham operators wishing to make contacts via aurora, must resort to CW ( Morse code ). CW signals returning from an auroral reflection have no distinct sound or tone but simply sound like

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6510-402: 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

6615-485: The earth where an entire hemisphere is visible providing outstanding communications capabilities from any two points on the earth within line of sight of the satellite; distances that are far beyond the reach of the LEOs. Transequatorial propagation, also known as (TEP), is a regular daytime occurrence on the 2 meter band over the equatorial regions and is common in the temperate latitudes in late spring, early summer and, to

6720-442: The exception of sporadic E, directional antennas such as Yagis or log periodic antennas are almost essential to take advantage of signal enhancements. When a well-equipped station with its antenna well-located “high and in the clear” is operating during a signal enhancement, astonishing distances can be bridged, momentarily approaching what is regularly possible on shortwave and mediumwave . Occasionally, signal bending in

6825-473: The exchange of signal level reports and location by grid square which is known as the Maidenhead Locator System . Two way ducting contacts can have very strong signals and are often made with moderate power, small antennas, and other types of modes. Long distance ducting contacts do occur using FM modes as well but for the most part go unnoticed by many FM operators. Another form of VHF propagation

6930-404: 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

7035-470: 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

7140-1274: 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

7245-459: 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

7350-428: 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}

7455-406: 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

7560-418: 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

7665-572: The internet) may suffer outages or feature degradation that impacts operations. Without simulating such outages during drills, it is difficult to assess the impact of or establish D-STAR service recovery procedures in the event of such failures. As of the fall of 2011, there has been almost no discussion in the ham radio literature regarding actual drills where D-STAR systems were tested with completely failed or even intermittent telecommunications infrastructure. Comprehensive emergency communications plans used by ARES and other such organizations should address

7770-675: The ircDDB and QuadNet2 networks and is licensed under GPL-2.0 . ircDDBGateway supports Icom controllers and repeaters, as well as homebrew repeaters and hotspots (simplex access points). It provides more linking and routing options over the Gateway V1 and G2. ircDDBGateway can run on various distributions of Linux and versions of Microsoft Windows. Computer requirements can be as simple as a Raspberry Pi . Refactored ircDDBGateway by Geoffery Merck F4FXL. Known to support Icom 3rd Generation repeaters. Various projects exist for gateway administrators to add "add-on" software to their gateways, including

7875-422: The longest distances, hams use moon bounce . VHF signals normally escape the Earth's atmosphere, so using the moon as a target is quite practical. Due to the distance involved and the very high path loss getting a readable signal bounced off the moon involves high power ~1,000 watts and steerable high gain antennas. Receiving these very weak return signals, again involves the use of high gain antennas (usually

7980-450: The most important, the ability for DV-Dongle users to communicate from the Internet to the radio users on the repeaters. There is often a misconception by users and system administrators alike that the Gateway 2.0 systems have these add-on features from dplus by default, a testament to the popularity of this add-on software. Dplus software development has an active following, and features such as multiple repeater/system connections similar to

8085-467: The most popular package called "dplus" created by Robin Cutshaw AA4RC. A large number of Gateway 2.0 systems are offering services added by this software package to their end-users, and users are getting used to having these features. Features include the ability to link systems directly, "voice mail" (a single inbox today), ability to play/record audio to and from the repeaters connected to the Gateway and

8190-553: The open-source tools, the Icom proprietary dsipsvd or "D-STAR IP Service Daemon" and a variety of crontab entries utilize a mixture of the local PostgreSQL and BIND servers to look up callsigns and "pcname" fields (stored in BIND) which are mapped to individual 10.x.x.x internal-only addresses for routing of both voice and data traffic between participating gateways. During installation, the Gateway 2.0 software installation script builds most of

8295-405: The openness of the rest of the D-STAR standard which can be implemented freely. As of 2017 the patents have expired, as announced by Bruce Perens, K6BP at the 2017 ARRL/TAPR DCC in his State of Digital Voice talk. The term 'D-STAR' is itself a registered trademark of Icom. Icom also holds a trademark for its stylized D-STAR logo. There is no indication Icom is charging other vendors to use any of

8400-422: The over-the-air protocol, D-STAR also provides specifications for network connectivity, enabling D-STAR radios to be connected to the Internet or other networks, allowing streams of voice or packet data to be routed via amateur radio. D-STAR compatible radios are manufactured by Icom , Kenwood , and FlexRadio Systems. In 1998 an investigation into finding a new way of bringing digital technology to amateur radio

8505-437: 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

8610-413: The possibility that such systems may not function as intended during major disasters. The loss of Internet does not degrade the local operation of a D-STAR repeater system. Over the Internet linking and routing of traffic may be degraded. Some groups are using microwave-based systems, such as HamWAN, to link repeaters. In Icom 's radio line, D-STAR used to significantly add to the cost of a radio, which

8715-413: The previous use of only BIND for "database" activities, the addition of both an administrative and end-user Web interface for registration which was previously handled via command-line commands by the Gateway V1 system administrators, dropping the requirement for static public IP addresses for gateways , and the ability of the software to use a fully qualified domain name to find and communicate with

8820-624: The recommended configuration uses CentOS Linux 5.1 with the latest updates, typically running ( kernel 2.4.20. glibc 2.3.2 and BIND 9.2.1 or later). The CPU should be 2.4 GHz or faster and the memory should at least be 512 MB or greater. There should be two network interface cards and at least 10 GB free of hard drive space which includes the OS install. Finally for middleware, Apache 2.0.59, Tomcat 5.5.20, mod_jk2 2.0.4, OpenSSL 0.9.8d, Java SE 5.0 and postgreSQL 8.2.3 are utilized, but these can be different as updates occur. Along with

8925-444: 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

9030-399: 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

9135-460: The same trail until it dissipates and can no longer reflect VHF signals with sufficient strength. This mode is often called burst transmission and can yield communication distances similar to sporadic E as described above. Another phenomenon that produces upper atmosphere ionization suitable for 2-meter DXing are the auroras . Since the ionization persists much longer than meteor trails, voice modulated radio signals may sometimes be used, but

9240-412: The same type used to transmit the signal) and a very low-noise front end RF amplifier and a frequency stable receiver. However, new and recent technological advances in weak signal detection has allowed the successful reception of signals off the moon using much smaller or less well equipped stations allowing reception of signals that are "in the noise" and not audible to the human ear. One of these modes

9345-410: The signal is no longer correctable, and when data loss is too great, audio artifacts can appear in the recovered audio. Many advanced D-STAR features rely on internet connections although simplex, repeated and crossband gateway voice and data communications do not. During widespread disasters that compromise commercial telecommunications infrastructure, D-STAR systems (as well as other modes that rely on

9450-437: The statute is still on the books. There are also California Penal Code statutes covering similar activities. Recently, however, with new legislation in various states, licensed ham radio operators are exempt from these prohibitions including exemptions from using a radio while driving. Such prohibitions or exemptions vary from state to state. Note: Federal law preempts many local ordinances and state laws which may prohibit

9555-632: The three awards differentiate between successful "traditional" phone/CW contact (the Brendan Trophies), successful "non-traditional" digital two-way contact (the Brendan Shields), and an award for the first verified reception in either direction, regardless of method (the Brendan Plates). Attempts at the Brendan awards have established contact, but further examination revealed the signal was bounced off

9660-498: The trust server, allowing for redundancy/failover options for the trust server administrators. Finally, a feature called "multicast" has been added for administrators to be able to provide users with a special "name" they can route calls to which will send their transmissions to up to ten other D-STAR repeaters at the same time. With cooperation between administrators, a "multicast group" can be created for multiple repeater networks or other events. Another additional feature of Gateway G2

9765-426: The trust server—a specialized central gateway system—which allows for lookups across a particular trust server domain. Only one "registration" per trust domain is required. Each amateur is set aside eight 10.x.x.x internal IP addresses for use with their callsign or radios, and various naming conventions are available to utilize these addresses if needed for specialized callsign routing . Most amateurs will need only

9870-409: The type of linking done by other popular repeater-linking systems ( IRLP and EchoLink ) are being worked on. Like other commercial digital modes ( P25 , TETRA , DMR , dPMR , NXDN , System Fusion ), D-STAR uses a closed-source proprietary voice codec ( AMBE ) that's patented by Digital Voice Systems, Inc. (DVSI) because it was the highest quality and only codec available in silicon when the system

9975-467: The upper and lower cutoff frequencies of, for example, a band-pass filter , a communication channel , or a signal spectrum . Baseband bandwidth 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

10080-451: 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

10185-485: The vertical polarization customarily used for local contacts. Stations that have antennas located in relatively high locations with views (from the antenna) clear to the horizon have a big advantage over other stations. Such stations are able to communicate 100–300 miles (160–480 km) consistently. It is usual for them to be heard at distances far beyond line of sight on a daily basis without help from signal enhancements. Signal enhancements are unusual circumstances in

10290-461: The voice codec hardware and/or license and partly to manufacturer research and development costs that has now been amortized. As is the case with any product, as more units were sold, the R&;D portion of the cost decreased over time. FlexRadio Systems D-STAR implementation requires the use of a $ 129 add-on module to their FLEX-6000 Series Radios. Many have argued that the proprietary codec constitutes

10395-602: The web interface, and in the radios themselves. The Gateway V1 software was similar to Gateway G2, and utilized Fedora Core 2+ or Red Hat Linux 9+ OS on a Pentium-grade 2.4 GHz or faster machine. Gateway software developed by Jonathan Naylor, G4KLX, has a larger network of repeaters and users and is being adopted by former Gateway G2 users as the G2 system is closed source, only supports Icom repeaters, and runs on Centos 5.x which will reach end of life in March 2017. ircDDBGateway operates on

10500-501: Was a 2-meter mobile unit designated IC-2200H. Icom followed up with 2 meter and 440 MHz handheld transceivers the next year. However, the yet to be released UT-118 add-on card was required for these radios to operate in D-STAR mode. Eventually, the card became available and once installed into the radios, it provided D-STAR connectivity. The June 2005 edition of the American Radio Relay League 's QST magazine reviewed

10605-410: Was a barrier to the adoption of the technology. While in 2006 the cost of a D-STAR radio was compared to that of a standard analog radio, and the price difference was nearly double, in 2024 D-STAR is standard fare in many amateur radio transceivers, fixed-base (Icom IC-9700), mobile (Icom IC-7100) and hand-held (Icom IC-705, IC-905, IC-50A and IC-52A). This decrease in price is due to the per-unit cost for

10710-590: Was developed by KB9KHM using a GMSK Node Adaptor developed by Satoshi Yasuda and DVAR Hotspot software developed by KB9KHM in 2008. This repeater could link over the Internet with other Icom repeater gateways and Reflectors via D-Plus. It did not support callsign routing or slash routing via the K5TIT G2 network. The first non-Icom D-STAR repeater fully supporting the K5TIT G2 network and D-Plus, GB7MH, went live on 10 September 2009, in West Sussex, England. Whilst waiting for

10815-458: Was launched in early 2016. OUFTI-1 is a CubeSat built by Belgian students at the University of Liège and I.S.I.L ( Haute École de la Province de Liège ). The name is an acronym for Orbital Utility For Telecommunication Innovation . The goal of the project is to develop expertise in various aspects of satellite design and operation. The satellite weighs just 1 kilogram and utilizes a UHF uplink and

10920-516: Was released. Amateur radio operators do not have access to the specification of this codec or the rights to implement it on their own without buying a licensed product. Amateurs have a long tradition of building, improving upon and experimenting with their own radio designs. The modern digital age equivalent of this would be designing and/or implementing codecs in software. Critics say the proprietary nature of AMBE and its availability only in hardware form (as ICs) discourages innovation. Even critics praise

11025-644: Was started. The process was funded by a ministry of the Japanese government, then called the Ministry of Posts and Telecommunications , and administered by the Japan Amateur Radio League . In 2001, D-STAR was published as the result of the research. In September 2003 Icom named Matt Yellen, KB7TSE (now K7DN), to lead its US D-STAR development program. Starting in April 2004 Icom began releasing new "D-STAR optional" hardware. The first to be released commercially,

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