Monday, December 27, 2010

【 Weak current College 】-audio and digital-audio chats 】

Walkie-talkie products in the functional properties of a column can always see the CTCSS and DTCS CDCSS, DCS, and QT, DQT, PL, TPL and DPL, English nouns, or Chinese name is audio, digital-audio, private line, digital private line, audio codec, audio codec for digital Asia etc, although the names are different, but marking machine has Asia audio signalling system functionality, just the description of different manufacturers.
-Audio signalling is divided into two kinds, one kind called Asia audio, another called digital-audio. -Audio signalling of the English name is ContinuousToneControlledSquelchSystem means continuous tone-coded squelch system. It is a lower than having audio frequency tone frequency (67-250.3HZ) attached to the audio signal transmission encoding recognition with signaling technology, because its tone frequency lower than 300HZ voice frequency, so called Asia audio technology. Kenwood Corporation will QT as the short name, and the audio Motorola this technique is called PL signalling standard. PL (PrivateLineCodes) mean private line coding, referred to as private line. PL signalling essentially CTCSS-audio signalling, Motorola is using private confidential line function to represent this technology.
And the digital-audio in English (CoutinusDigitalControlledSquelechSystem) of which the Chinese meaning is the consecutive number-coded squelch system, hereinafter referred to as DCS or DTCS. DQT says digital-audio, and Motorola is to call the DPL (digital private line). Digital-audio and audio effects are the same, the difference is that it is a digital encoding and transmission of audio signal together. CTCSS or DCS belong to the international common signalling standard. CTCSS frequency range from 67.0HZ-250.3HZ 38 standard code from 01-38 of each code that corresponds to the frequency, such as code 01 corresponding frequency 67.0HZ. But Motorola PL private line of code in English, and numbers to represent, such as the frequency of theEnglish code 67HZ "XZ". In addition to the standard code, there are non-standards-audio code, depending on the circumstances of the manufacturers below 300HZ audio frequency selection. Such as: Motorola GP88 walkie-talkie to 40 group codes, malanshi of HX290 and otherwise aikemu IC-V8 of 50 group, Kenwood's TK-K2AT K4AT, TK271A 471A 42 group, 39 group, TK7108 TK808 37 group standard code + 97.4M non-standard code. While DCS digital-audio General are 104 group code, but there are a few models, such as DCS codes for IC-V8 machine 104 × 2 groups.
Use the intercom design-audio technology with the aim of avoiding interference between different users, avoid listening to the independent call and interference signals. Because it can be a common channel to stop from other user's voice and signaling interference, also known as a code lock (ToneLock). When the radio transmitter to send voice signals at the same time, accompanied by a transmitter continuously emit-audio continuous signal after the modulation in the same channel launch out. When the receiver receives the signal and the audio signal. -Audio input signal after filter shaping CPU decode in, and the machine out-of-the-CTCSS (DCS) are compared to the identification codes to determine whether to open the squelch circuit, only same-audio codes, squelch circuit audio output to open the sound through speakers. Therefore it can share the channel to stop unwanted users from other voice and other signalling interference. So you can tell it is through the Asia-Pacific audio (digital-audio) signalling encoding and decoding to improve communication network against outside interference ability and resolve non-network users access signalling recognition system. At the same time, CTCSS (DCS) has selected calling features, use consecutive single audio encoding (encoding) to select the call, and always and transmission of voice signals simultaneously also is the most effective way of DSC. The master calls as long as you press the PTT can issue a group call or all calls, walkie-talkie call ends without having to press the hook, compared to telephone interconnect way manual coding DSC (DTMF) to simple, easy and fast.
CTCSS (DCS) specification requirements are higher, should comply with the electronic industries Association (EIA) standard. General requirements-audio frequency stability error is less than ± 1%, standard-audio single audio offset: 0.5KHZ ± 20%, the standard words audio offset: 3KHZ, maximum frequency deviation: 5KHZ; tone squelch sensitivity: receiver output SNR to work reliably when 8db. DCS with CTCSS some technologies are similar. Digital-audio encoding is carried out under Asia-audio rate binary signal DC change, and the biggest difference between CTCSS is after the end of each emission can automatically send a tone as "close 134HZ codes" (a way to suppress noise tail). DCS than CTCSS decoding speed, the error rate is also lower. At the same time the group code of up to 104, make it in the same channel can have more users. Obviously the more advanced than the CTCSS DCS, of course in technical difficulty or greater, in domestic machine DCS technology mature cross the border.
-Audio (digital-audio) technology is already widely used in radio design, thereby increasing the overall level of interphone. Its advantages: 1. to prevent illegal access by user usage of the channel. 2, strong anti-interference ability, particularly in transit communication system can effectively prevent the interference signal interference on the turntable. 3. implementation of small regional frequency reuse, increased frequency of utilization, up frequency sharing. 4, you can implement different constituency groups call, call waiting for DSC function, simple operation, convenient and practical. Understanding Asian audio technology application of the radio, you can better perform its function.

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