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76-405: In some designs, the squelch threshold is preset. For example, television squelch settings are usually preset. Receivers in base stations , or repeaters at remote mountain top sites, are usually not adjustable remotely from the control point. In two-way radios (also known as radiotelephones ), the received signal level required to unsquelch (un-mute) the receiver may be fixed or adjustable with

152-417: A CB shack . In the context of external land surveying, a base station is a GPS receiver at an accurately-known fixed location which is used to derive correction information for nearby portable GPS receivers. This correction data allows propagation and other effects to be corrected out of the position data obtained by the mobile stations, which gives greatly increased location precision and accuracy over

228-506: A DS-1 , or radio links. The consoles multiplex transmit commands onto remote control circuits. Some system configurations require duplex, or four wire, audio paths from the base station to the console. Others require only a two-wire or half duplex link. Interference could be defined as receiving any signal other than from a radio in your own system. To avoid interference from users on the same channel, or interference from nearby strong signals on another channel, professional base stations use

304-461: A product or service from a particular source and distinguishes it from others. Trademarks can also extend to non-traditional marks like drawings, symbols, 3D shapes like product designs or packaging, sounds, scents, or specific colors used to create a unique identity. For example, Pepsi® is a registered trademark associated with soft drinks, and the distinctive shape of the Coca-Cola® bottle

380-483: A "2+2" system) that was heavily used by fire department dispatch systems in the US. Later selective call systems used paging system technology that made use of a burst of five sequential tones. DCS (Digital-Coded Squelch), generically known as CDCSS (Continuous Digital-Coded Squelch System), was designed as the digital replacement for CTCSS. In the same way that a single CTCSS tone would be used on an entire group of radios,

456-592: A "first-to-file" system, which grants rights to the first entity to register the mark. However, well-known trademarks are an exception, as they may receive protection even without registration. In contrast, a few countries, like the United States, Canada, and Australia, follow a "first-to-use" or hybrid system, where using the mark in commerce can establish certain rights, even without registration. However, registration in these countries still provides stronger legal protection and enforcement. For example, in

532-609: A 3-digit octal number. Note that the first bit transmitted is the LSB, so the code is "backwards" from the transmitted bit order. Only 83 of the 512 possible codes are available, to prevent falsing due to alignment collisions. DCS codes are standardized by the Telecommunications Industry Association with the following 83 codes being found in their most recent standard, however, some systems use non-standard codes. For those PMR446 radios with 121 codes,

608-637: A brand in the marketplace and distinguish it from competitors. A service mark , also covered under the Lanham Act, is a type of trademark used to identify services rather than goods. The term trademark is used to refer to both trademarks and service marks. Similarly, the World Intellectual Property Organization (WIPO) defines a trademark as a sign capable of distinguishing the goods or services of one enterprise from those of other enterprises. WIPO administers

684-659: A combination of: Base stations are sometimes called control or fixed stations in US Federal Communications Commission licensing. These terms are defined in regulations inside Part 90 of the commissions regulations. In US licensing jargon, types of base stations include: In amateur radio , a base station also communicates with mobile rigs but for hobby or family communications. Amateur systems sometimes serve as dispatch radio systems during disasters, search and rescue mobilizations, or other emergencies. An Australian UHF CB base station

760-444: A company or product. A trademark, by contrast, offers legal protection for a brand with enforceable rights over the brand's identity and distinguishing elements. Trademark law is designed to fulfill the public policy objective of consumer protection , by preventing the public from being misled as to the origin or quality of a product or service. By identifying the commercial source of products and services, trademarks facilitate

836-467: A competitor uses the same or a confusingly similar trademark for the same or similar products in a jurisdiction where the trademark is protected. This concept is recognized in many jurisdictions, including the United States, the European Union, and other countries, though specific legal standards may vary. To establish trademark infringement in court, the plaintiff generally must show: Trademark

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912-630: A distinctive label or ticket'. In the United States , Congress first attempted to establish a federal trademark regime in 1870. This statute purported to be an exercise of Congress' Copyright Clause powers. However, the Supreme Court struck down the 1870 statute in the Trade-Mark Cases later on in the decade. In 1881, Congress passed a new trademark act, this time according to its Commerce Clause powers. Congress revised

988-438: A fixed location and used to communicate as part of one of the following: Base stations use RF power amplifiers ( radio-frequency power amplifiers) to transmit and receive signals. The most common RF power amplifiers are metal–oxide–semiconductor field-effect transistors (MOSFETs), particularly LDMOS ( power MOSFET ) RF amplifiers. RF LDMOS amplifiers replaced RF bipolar transistor amplifiers in most base stations during

1064-437: A generic product or service name. They should stand out from the surrounding text using capital letters, bold type, italics, color, underlining, quotation marks, or a unique stylized format. For example, say “LEGO® toy blocks” instead of “Lego’s.” A trademark may be designated by the following symbols: While ™ and ℠ apply to unregistered marks (™ for goods and ℠ for services), the ® symbol indicates official registration with

1140-428: A knob or a sequence of button presses. Typically the operator will adjust the control until noise is heard, and then adjust in the opposite direction until the noise is squelched. At this point, a weak signal will unsquelch the receiver and be heard by the operator. Further adjustment will increase the level of signal required to unsquelch the receiver. Some applications have the receiver tied to other equipment that uses

1216-609: A loss of rights in the trademark. It is still possible to make significant changes to the underlying goods or services during a sale without jeopardizing the trademark, but companies will often contract with the sellers to help transition the mark and goods or services to the new owners to ensure continuity of the trademark. Trademarks are often confused with patents and copyrights . Although all three laws protect forms of intangible property, collectively known as intellectual property (IP), they each have different purposes and objectives: Among these types of IP, only trademark law offers

1292-550: A primary selected channel is routed to the select speaker and to a headset. Each channel has a busy light which flashes when someone talks on the associated channel. Base stations can be local controlled or remote controlled. Local controlled base stations are operated by front panel controls on the base station cabinet. Remote control base stations can be operated over tone- or DC-remote circuits. The dispatch point console and remote base station are connected by leased private line telephone circuits, (sometimes called RTO circuit s),

1368-551: A properly designed dispatch center with several staff members, this allows each dispatcher to communicate simultaneously, independently of one another, on a different channel as necessary. For example, a taxi company dispatch center may have one base station on a high-rise building in Boston and another on a different channel in Providence . Each taxi dispatcher could communicate with taxis in either Boston or Providence by selecting

1444-701: A whole. Trademark protection does not apply to utilitarian features of a product such as the plastic interlocking studs on Lego bricks. The earliest examples of use of markings date back to around 15,000 years ago in Prehistory . Similar to branding practices, the Lascaux cave paintings in France, for instance, depict bulls with marks, which experts believe may have served as personal marks to indicate livestock ownership. Around 6,000 years ago, Egyptian masonry featured quarry marks and stonecutters' signs to identify

1520-493: Is "escalator," which was once a trademark. In contrast, patents have a fixed term, typically lasting 20 years from the filing date, after which the invention enters the public domain. Copyrights generally last for the life of the author plus an additional 50 to 70 years (depending on the jurisdiction), after which the protected work enters the public domain. Although intellectual property laws such as these are theoretically distinct, more than one type may afford protection to

1596-651: Is a registered trademark protecting Coca-Cola's packaging design. The primary function of a trademark is to identify the source of goods or services and prevent consumers from confusing them with those from other sources. Legal protection for trademarks is typically secured through registration with governmental agencies, such as the United States Patent and Trademark Office (USPTO) or the European Union Intellectual Property Office (EUIPO). Registration provides

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1672-434: Is another example of part of a system used for hobby or family communications. Wireless telephone differ from two-way radios in that: A wireless telephone base station communicates with a mobile or hand-held phone. For example, in a wireless telephone system, the signals from one or more mobile telephones in an area are received at a nearby base station, which then connects the call to the land-line network. Other equipment

1748-435: Is inherently distinctive (able to identify and distinguish a single source of goods or services), often falling into categories such as suggestive, fanciful, or arbitrary, and is therefore registerable. In contrast, weak trademarks tend to be either descriptive or generic and may not be registerable. The registration process typically begins with a trademark clearance search to identify potential conflicts that could prevent

1824-511: Is interchangeable. Old and new radios with CTCSS and radios across manufacturers are compatible. For those PMR446 radios with 38 codes, the codes 0 to 38 are CTCSS Tones: Selcall (Selective Calling) transmits a burst of up to five in-band audio tones at the beginning of each transmission. This feature (sometimes called "tone burst") is common in European systems. Early systems used one tone (commonly called "Tone Burst"). Several tones were used,

1900-471: Is involved depending on the system architecture. Mobile telephone provider networks, such as European GSM networks, may involve carrier , microwave radio , and switching facilities to connect the call. In the case of a portable phone such as a US cordless phone, the connection is directly connected to a wired land line. While low levels of radio-frequency power are usually considered to have negligible effects on health, national and local regulations restrict

1976-498: Is more reliable than carrier squelch. A noise squelch circuit is noise-operated and can be used in AM or FM receivers, and relies on the receiver quieting in the presence of an AM or FM carrier. To minimize the effects of voice audio on squelch operation, the audio from the receiver's detector is passed through a high-pass filter , typically passing 4,000 Hz (4kHz) and above, leaving only high frequency noise. The squelch control adjusts

2052-430: Is no convincing scientific evidence that the weak RF signals from base stations and wireless networks cause adverse health effects." The consensus of the scientific community is that the power from these mobile phone base station antennas is too low to produce health hazards as long as people are kept away from direct access to the antennas. However, current international exposure guidelines ( ICNIRP ) are based largely on

2128-503: Is required to act as the "basic mark." In the international application, the trademark owner can designate one or more Madrid System Member countries for protection. Each designated country’s trademark office will review the Madrid application under its local laws to grant or refuse protection. In the United States, for example, a trademark must first be registered or pending with the U.S. Patent and Trademark Office (USPTO) to serve as

2204-466: Is subject to various defenses, such as abandonment, limitations on geographic scope , and fair use. In the United States, the fair use defense protects many of the interests in free expression related to those protected by the First Amendment . Fair use may be asserted on two grounds, either that the alleged infringer is using the mark to describe accurately an aspect of its products, or that

2280-425: Is the most simple variant of all. It functions strictly on the signal strength , such as when a television mutes the audio or blanks the video on "empty" channels , or when a walkie-talkie mutes the audio when no signal is present. Carrier squelch uses receiver Automatic gain control (AGC) to determine the squelch threshold. Single-sideband modulation (SSB) typically uses carrier squelch . Noise squelch

2356-402: Is used in the context of mobile telephony , wireless computer networking and other wireless communications and in land surveying . In surveying, it is a GPS receiver at a known position, while in wireless communications it is a transceiver connecting a number of other devices to one another and/or to a wider area. In mobile telephony, it provides the connection between mobile phones and

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2432-450: Is used to keep commercial and amateur radio repeaters from continually transmitting . Since a carrier squelch receiver cannot tell a valid carrier from a spurious signal (noise, etc.), CTCSS is often used as well, as it avoids false keyups. Use of CTCSS is especially helpful on congested frequencies or on frequency bands prone to skip and during band openings. Professional wireless microphones use squelch to avoid reproducing noise when

2508-722: The Madrid Protocol , which allows trademark owners worldwide to file one application to register their trademark in multiple countries. Almost anything that identifies the source of goods or services can serve as a trademark. In addition to words, slogans, designs, or combinations of these, trademarks can also include non-traditional marks like sounds, scents, or colors. Under the broad heading of trademarks, there are several specific types commonly encountered, such as trade dress, collective marks, and certification marks: To maintain distinctiveness , trademarks should function as adjectives, not as nouns or verbs, and be paired with

2584-763: The TRIPS Agreement sets minimum standards for trademark protection and enforcement that all member countries must follow. The term trademark can also be spelled trade mark in regions such as the EU, UK, and Australia, and as trade-mark in Canada. Despite the different spellings, all three terms denote the same concept. In the United States, the Lanham Act defines a trademark as any word, phrase, symbol, design, or combination of these things used to identify goods or services. Trademarks help consumers recognize

2660-465: The gain of an amplifier which varies the level of the noise coming out of the filter. This noise is rectified , producing a DC voltage when noise is present. The presence of continuous noise on an idle channel creates a DC voltage which turns the receiver audio off. When a signal with little or no noise is received, the noise-derived voltage is reduced and the receiver audio is unmuted. Noise squelch can be defeated by intermodulation present in

2736-419: The thermal effects of base station emissions, NOT considering the non-thermal effects harmless. Fuel cell backup power systems are added to critical base stations or cell sites to provide emergency power. Trademark A trademark (also written trade mark or trade-mark ) is a form of intellectual property that consists of a word, phrase, symbol, design, or a combination that identifies

2812-712: The "basic mark" necessary for Madrid filings. The trademark registration process with the USPTO generally follows these steps: Trademark owners seeking protection in multiple jurisdictions have two options: the Paris route, under the Paris Convention , or the Madrid System , which is administered by WIPO . The Paris route, covering 180 countries and also known as the "direct route," requires filing separate applications with each country’s IP office. In contrast,

2888-415: The 1990s, leading to the wireless revolution . In professional two-way radio systems, a base station is used to maintain contact with a dispatch fleet of hand-held or mobile radios, and/or to activate one-way paging receivers. The base station is one end of a communications link. The other end is a movable vehicle-mounted radio or walkie-talkie. Examples of base station uses in two-way radio include

2964-429: The European Union requires "genuine use" of the mark within a continuous five-year period following registration to maintain the trademark, with non-use potentially resulting in revocation. The trademark owner must enforce their rights to preserve the trademark's distinctiveness , prevent trademark infringement, and avoid dilution. Enforcement after registration generally involves: Trademark infringement occurs when

3040-468: The Madrid System streamlines the process by allowing a single Madrid application, built on an existing or applied-for national or regional registration (the "basic mark"), to extend protection to up to 131 countries. Unlike patents and copyrights , which have fixed expiration dates, trademark registrations typically have an initial term of 10 years and can be renewed indefinitely, as long as

3116-577: The Roman Empire. Other notable trademarks that have been used for a long time include Stella Artois , which claims use of its mark since 1366, and Löwenbräu , which claims use of its lion mark since 1383. The first trademark legislation was passed by the Parliament of England under the reign of King Henry III in 1266, which required all bakers to use a distinctive mark for the bread they sold. The first modern trademark laws emerged in

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3192-528: The Trademark Act in 1905. The Lanham Act of 1946 updated the law and has served, with several amendments, as the primary federal law on trademarks. The Trade Marks Act 1938 in the United Kingdom set up the first registration system based on the "intent-to-use" principle. The Act also established an application publishing procedure and expanded the rights of the trademark holder to include

3268-492: The Trademark Electronic Search System (TESS) in 2023. A comprehensive clearance search involves checking the USPTO database for federally registered and applied-for trademarks, state trademark databases, and the internet to see if someone else has already registered that trademark or a similar one. The search should also include looking at both words and designs. To search for similar designs in

3344-486: The UK Patent Office for the first time. Registration was considered to comprise prima facie evidence of ownership of a trademark and registration of marks began on 1 January 1876. The 1875 Act defined a registrable trade mark as a device or mark, or name of an individual or firm printed in some particular and distinctive manner; or a written signature or copy of a written signature of an individual or firm; or

3420-400: The USPTO database, design search codes must be used. WIPO ’s Global Brand Database provides international access to trademarks and emblems. Trademark owners can either maintain protection at the national level or expand internationally through the Madrid System by building on their national registration. To pursue international protection, a national registration or pending application

3496-584: The United States, trademark rights are established either (1) through first use of the mark in commerce, creating common law rights limited to the geographic areas of use, or (2) through federal registration with the U.S. Patent and Trademark Office (USPTO), with use in commerce required to maintain the registration. Federal registration with the USPTO provides additional benefits, such as: Trademark law grants legal protection to "distinctive" trademarks, which are marks that allow consumers to easily associate them with specific products or services. A strong trademark

3572-459: The alleged infringer is using the mark to identify the mark owner. One of the most visible proofs that trademarks provide a limited right in the U.S. comes from the comparative advertising that is seen throughout U.S. media. An example of the first type is that although Maytag owns the trademark "Whisper Quiet" for its dishwashers, makers of other products may describe their goods as being "whisper quiet" so long as these products do not fall under

3648-465: The audio muting control voltage, as a "signal present" indication; for example, in a repeater the act of the receiver unmuting will switch on the transmitter. Squelch can be opened (turned off), which allows all signals to be heard, including radio frequency noise on the receiving frequency. This can be useful when trying to hear distant or otherwise weak signals, for example in DXing . Carrier squelch

3724-438: The barring of trademark use even in cases where confusion remained unlikely. This Act served as a model for similar legislation elsewhere. The oldest registered trademark has various claimants, enumerated below: Trademark protection can be acquired through registration and/or, in certain countries, through use. Globally, the most common method for establishing trademark rights is registration. Most countries operate under

3800-440: The codes 39 to 121 are DCS codes: XTCSS is the newest signalling technique, and provides 99 codes with the added advantage of "silent operation". XTCSS-fitted radios are purposed to enjoy more privacy and flexibility of operation. XTCSS is implemented as a combination of CTCSS and in-band signalling. Squelch was invented first and is still in wide use in two-way radio. Squelch of any kind is used to indicate loss of signal, which

3876-400: The design of base stations to limit exposure to electromagnetic fields . Technical measures to limit exposure include restricting the radio frequency power emitted by the station, elevating the antenna above ground level, changes to the antenna pattern, and barriers to foot or road traffic. For typical base stations, significant electromagnetic energy is only emitted at the antenna, not along

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3952-415: The dispatch of tow trucks and taxicabs . Professional base station radios are often one channel. In lightly used base stations, a multi-channel unit may be employed. In heavily used systems, the capability for additional channels, where needed, is accomplished by installing an additional base station for each channel. Each base station appears as a single channel on the dispatch center control console. In

4028-407: The high-pass band. For this reason, many receivers with noise squelch will also use a carrier squelch set at a higher threshold than the noise squelch . Tone squelch, or another form of selective calling, is sometimes used to solve interference problems. Where more than one user is on the same channel ( co-channel users), selective calling addresses a subset of all receivers. Instead of turning on

4104-409: The identification of products and services which meet the expectations of consumers as to the quality and other characteristics. Trademarks may also serve as an incentive for manufacturers, providers, or suppliers to consistently provide quality products or services to maintain their business reputation. Furthermore, if a trademark owner does not maintain quality control and adequate supervision about

4180-574: The late 19th century. In France, the first comprehensive trademark system in the world was passed into law in 1857 with the "Manufacture and Goods Mark Act". In Britain, the Merchandise Marks Act 1862 made it a criminal offense to imitate another's trade mark 'with intent to defraud or to enable another to defraud'. The passing of the Trade Marks Registration Act 1875 allowed formal registration of trademarks at

4256-495: The length of the antenna tower. Because mobile phones and their base stations are two-way radios, they produce radio-frequency ( RF ) radiation in order to communicate, exposing people near them to RF radiation giving concerns about mobile phone radiation and health . Hand-held mobile telephones are relatively low power so the RF radiation exposures from them are generally low. The World Health Organization has concluded that "there

4332-532: The manufacture and provision of products or services supplied by a licensee, such "naked licensing" will eventually adversely affect the owner's rights in the trademark. For US law see, ex. Eva's Bridal Ltd. v. Halanick Enterprises, Inc. 639 F.3d 788 (7th Cor. 2011). This proposition has, however, been watered down by the judgment of the House of Lords in the case of Scandecor Development AB v. Scandecor Marketing AB et al. [2001] UKHL 21; wherein it has been held that

4408-415: The mark remains in continuous use in commerce. If the trademark owner stops using the mark for too long (typically three to five years, depending on the jurisdiction), the trademark rights may be lost. For example, in the United States, trademark rights are based on use in commerce. If a mark is not used for three consecutive years, it is presumed abandoned and becomes vulnerable to challenges. Similarly,

4484-476: The mere fact that a bare license (the equivalent of the United States concept of a naked license) has been granted did not automatically mean that a trademark was liable to mislead. By the same token, trademark holders must be cautious in the sale of their mark for similar reasons as apply to licensing. When assigning an interest in a trademark, if the associated product or service is not transferred with it, then this may be an "assignment-in-gross" and could lead to

4560-405: The most common being 1,750 Hz, which is still used in European amateur radio repeater systems. The addressing scheme provided by one tone was not enough, so a two-tone system was devised—one tone followed by a second tone (sometimes called a "1+1" system). Motorola later marketed a system called "Quik-Call" that used two simultaneous tones followed by two more simultaneous tones (sometimes called

4636-427: The owner certain exclusive rights and provides legal remedies against unauthorized use by others. Trademark laws vary by jurisdiction but generally allow owners to enforce their rights against infringement, dilution, or unfair competition. International agreements, such as the Paris Convention and the Madrid Protocol , simplify the registration and protection of trademarks across multiple countries. Additionally,

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4712-421: The possibility of perpetual rights, provided the trademark is continuously used and renewed. However, if a trademark is no longer in use, its registration may be subject to cancellation. Trademarks can also lose protection through genericide , a process where a trademark becomes so widely used to refer to a category of goods or services that it loses its distinctiveness and legal protection. A well-known example

4788-469: The radio's encoder-decoder will use the same code as radios in the existing system. DCS adds a 134.4  bit/s (sub-audible) bitstream to the transmitted audio. The code word is a 23-bit Golay (23,12) code which has the ability to detect and correct errors of 3 or fewer bits. The word consists of 12 data bits followed by 11 check bits. The last 3 data bits are a fixed '001', this leaves 9 code bits (512 possibilities) which are conventionally represented as

4864-578: The receiver audio for any signal, the audio turns on only in the presence of the correct selective calling code. This is akin to the use of a lock on a door. A carrier squelch is unlocked and will let any signal in. Selective calling locks out all signals except ones with the correct key to the lock (the correct code). In non-critical uses, selective calling can also be used to hide the presence of interfering signals such as receiver-produced intermodulation. Receivers with poor specifications—such as inexpensive police scanners or low-cost mobile radios—cannot reject

4940-514: The receiver does not receive enough signal from the microphone. Most professional models have adjustable squelch, usually set with a screwdriver adjustment or front-panel control on the receiver. Base station Base station (or base radio station ) is – according to the International Telecommunication Union 's (ITU) Radio Regulations (RR) – a " land station in the land mobile service ." The term

5016-527: The registration of the trademark. A comprehensive clearance search can help avoid costly and time-consuming issues, such as refusal to register, opposition or cancellation proceedings, or a trademark infringement lawsuit. In the United States, the USPTO maintains a publicly accessible database of registered trademarks. This database can be searched using the Trademark Search system, which replaced

5092-425: The relevant national authority. Using the ® symbol for unregistered trademarks is misleading and can be treated as unfair business practice. It may also result in civil or criminal penalties. A brand is a marketing concept that reflects how consumers perceive a product or service. It has a much wider meaning and refers to the proprietary visual, emotional, rational, and cultural image that customers associate with

5168-435: The respective base station on his or her console. In dispatching centers it is common for eight or more radio base stations to be connected to a single dispatching console. Dispatching personnel can tell which channel a message is being received on by a combination of local protocol, unit identifiers, volume settings, and busy indicator lights. A typical console has two speakers identified as select and unselect . Audio from

5244-444: The results obtained by uncorrected GPS receivers. In the area of wireless computer networking, a base station is a radio receiver/transmitter that serves as the hub of the local wireless network, and may also be the gateway between a wired network and the wireless network. It typically consists of a low-power transmitter and wireless router . In radio communications, a base station is a wireless communications station installed at

5320-453: The same DCS code is used in a group of radios. DCS is also referred to as Digital Private Line (or DPL ), another trademark of Motorola, and likewise, General Electric's implementation of DCS is referred to as Digital Channel Guard (or DCG ). Despite the fact that it is not a tone, DCS is also called DTCS (Digital Tone Code Squelch) by Icom , and other names by other manufacturers. Radios with DCS options are generally compatible, provided

5396-426: The same article. For example, the particular design of a bottle may qualify for copyright protection as a non-utilitarian [sculpture], or trademark protection based on its shape, or the ' trade dress ' appearance of the bottle as a whole may be protectable. Titles and character names from books or movies may also be protectable as trademarks while the works from which they are drawn may qualify for copyright protection as

5472-405: The same category of goods the trademark is protected under. An example of the second type is that Audi can run advertisements saying that a trade publication has rated an Audi model higher than a BMW model since they are only using "BMW" to identify the competitor. In a related sense, an auto mechanic can truthfully advertise that he services Volkswagens , and a former Playboy Playmate of

5548-488: The stone's origin and the workers responsible. Wine amphorae marked with seals were also found in the tomb of Pharaoh Tutankhamun , who ruled ancient Egypt more than 3,000 years ago. Over 2,000 years ago, Chinese manufacturers sold goods marked with identifying symbols in the Mediterranean region. Trademarks have also been discovered on pottery, porcelain, and swords produced by merchants in ancient Greece and

5624-482: The strong signals present in urban environments. The interference will still be present, and will still degrade system performance, but by using selective calling the user will not have to hear the noises produced by receiving the interference. Four different techniques are commonly used. Selective calling can be regarded as a form of in-band signaling . CTCSS (Continuous Tone-Coded Squelch System) continuously superimposes any one of about 50 low-pitch audio tones on

5700-538: The transmitted signal, ranging from 67 to 254 Hz . The original tone set was 10, then 32 tones, and has been expanded even further over the years. CTCSS is often called PL tone (for Private Line , a trademark of Motorola ), or simply tone squelch . General Electric 's implementation of CTCSS is called Channel Guard (or CG ). RCA Corporation used the name Quiet Channel , or QC . There are many other company-specific names used by radio vendors to describe compatible options. Any CTCSS system that has compatible tones

5776-471: The wider telephone network . In a computer network , it is a transceiver acting as a switch for computers in the network, possibly connecting them to a/another local area network and/or the Internet . In traditional wireless communications, it can refer to the hub of a dispatch fleet such as a taxi or delivery fleet, the base of a TETRA network as used by government and emergency services or

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