Weak current College】 【civilian buildings Talkback intercom system new standard GA / T 72-2005 and the old standard GA/T72-1994 main difference.

<br> <br> The name change <br> Standard name from "civilian buildings Talkback intercom electronic security door General technical conditions" to "civilian buildings Talkback intercom system and general technical requirements for electronic security." GA/T72-2005 on civilian .buildings Talkback intercom system and electric control door respectively, proposed technical requirements and test methods. This is because the civilian buildings Talkback intercom system mainly electronics, with a small amount of and part of the mechanical and electrical products composition; electronic door is mainly mechanical products ., with a little and some mechanical and electrical products, small portion contains electronic products; here the door basically is a mechanical lock and control products, General machinery and small electronic devices. <br> New and old standard core differences <br> Old standard .GA/T72-lack of 1994: receiver pieces generally refers to the electret microphone and voice devices means micro souba. For other parts of the receiver and the last transmission devices considered inadequate. In fact, in the late 1990s, as part of a small .quantity of imported and domestic civilian buildings Talkback intercom system, telephone receiver and a universal voice device is the use of the telephone of electro-acoustic devices or other devices. For this type of product in the detection occurs, according to the GA/T72- .1994 standard detection will produce some pass and pass, but the actual use is possible, the results are still very good. If convicted of such products are not qualified to be a problem. After studies at that time, we use some alternative methods, the .sound source b / K corporate standards of sound intensity of the sound source, the sound-level meter test used. Through research and trial and error over and over, get one conclusion: GA/T72-1994 standard test methods, without considering or inadequate .by words and voice devices on the system of subjective and objective evaluation, resulting in inconsistent. <br> GA/T72-2005 adopted the full sound of test methods for assessing value <br> In GA/T72-1994 "civilian buildings Talkback intercom .electronic security door General technical conditions "on the audio of the test using electrical signals measured, is not considered insufficient consideration by words or and last transmission devices on the system of subjective and objective evaluation of the impact is easy to create. In the past have .also been used to compensate for methods such as using the standard sound level of sound sources and secondary test used sound level meter. <br> The new standard for the civilian buildings Talkback intercom system and electric control door General technical conditions "on the audio indicator .tests with simulation and emulation for the mouth and ear the whole sound degree evaluation value test method, presented for call transfer characteristics of five technical requirements. The entire testing process includes acoustic-electric, electro-acoustic transformation to more realistic reflection of civilian buildings Talkback .intercom system performance and the actual call capacity. <br> GA/T72-1994 main electrical properties <br> Primary respiratory passages, answer channel audio response: 300-3400HZ range, relative to the magnitude of the changes to 1000HZ in + 3db range .; <br> Primary respiratory passages, answer channel harmonic distortion should not greater than 5%; <br> SNR: response channel, â § 35db, master call channel, â § 40db; <br> Audio output power without distortion: answer channel ., â • 100mv, master call channel, â • 5mv; <br> Channel input electric power: should answer channel, â § 40mv, master call channel, â § 30mv; <br> Microphone sensitivity: rating should be consistent with the requirements .of the three-level SJ2055 OT electret microphone; <br> Vibrating ring pressure, â • 70db (A). <br> GA/T72-2005 standard call transfer features <br> Overall loudness rating value (OLR): his mouth from .the sender to receive-side reference point ear reference point between a measure of overall loudness, expressed with db; <br> Response channel full loudness rating value: 18db + 5db; <br> Main call channel of loudness rating value: 13db + 5db .; <br> Frequency response: response channel and master call allow tolerance in standard channels; <br> Nonlinear distortion: when the incentive sound pressure is when answering 0dbPa and main call channel their nonlinear distortion should not more than 7%; <br> .Signal to noise ratio:, â • answer channel, main call channel 30db, â • 35db; <br> Side tone masking evaluation (STMR): indoor unit handles client side code masking assessment value (STMR) should be not less than 5db; .<br> Vibrating ring level: indoor machine vibration ring level shall be not less than 70db (A). <br> New and old standard key differences <br> Old standard GA/T72-1994, receiver parts making a device itself of loudness ., frequency response, distortion, and other indicators are not the system test, systems standards have also done a lot of testing, then most of the receiver and voice devices. <br> New standard GA/T72-2005, the entire testing process includes .acoustic-electric, electro-acoustic transformation to more realistic reflection of civilian buildings Talkback intercom system performance and the quality of the actual call. <br> Running-in of the new and old standards <br> Some products will pass the old standard, .but with the new standard tests, the original is available through most of the products, less some products will have a small number of indicators cannot be agreed, but after going through by fine-tuning. Running-in time, we should recognize the new .standard is a great progress. <br> <br> <br> <br> <br>.