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Advisor(s)
Abstract(s)
No quotidiano é comum a utilização de sistemas de eletrónica de Áudio para realizar todas as fases de transmissão, receção, configuração e exposição das ondas sonoras. Neste contexto, implementa-se no presente projeto sistemas de eletrónica de Áudio analógica que permitem a receção controlada de um sinal sonoro, nivelando-o a uma amplitude pré-definida, mas manualmente alterável, com o objetivo de prover ao utilizador uma experiência de volume sonoro independente das variabilidades de amplitude do sinal à
entrada do sistema. Mais ainda, desenvolve-se um circuito de configuração sonora que permite variar a quantidade de amplificação do volume sonoro ativamente através do controlo ativo de volume (CAV) de Baxandall, o qual é colocado em série com um circuito de melhoria da qualidade da onda sonora a ser transmitida à saída, através da filtragem de frequências eletromagnéticas nefastas à formação de um sinal sonoro, ou seja, exteriores à banda de frequências entre os 20 Hertz (Hz) e os 20 quilo-Hertz (103 Hz, ou, kHz). Adicionalmente, dimensiona-se e implementa-se um equalizador gráfico de 4 bandas, com
frequências centrais de 250 Hz, 1 kHz, 4 kHz e 16 kHz, onde cada uma das bandas é realizada eletronicamente através de filtros passa-banda de oitava banda, com a frequência fundamental de manipulação configurada para as preconizadas e referidas anteriormente. Este circuito permite que se altere individualmente a influência em amplitude de cada um das frequências, permitindo ao utilizador a capacidade de percecionar a configuração espetral mais apropriada ao seu gosto. Ao longo do desenvolvimento do relatório expõe-se que uma vantagem dos circuitos desenvolvidos é o custo associado à construção de cada um deles, uma vez que para se realizarem as funcionalidades descritas, os circuitos acarretam um custo inferior à dezena de euro. Por outro lado, vê-se a dificuldade de implementação e a falta de versatilidade
dos circuitos com o desvantagens das soluções analógicas preconizadas para a implementação das funcionalidades pretendidas para os sistemas de captação e configuração de voz e Áudio. Como método de avaliação das soluções preconizadas para o projeto, recorre-se à utilização das ferramentas tecnológicas Matlab e ORCaD PSpice para a verificação computacional do dimensionamento teórico desenvolvido para cada um dos circuitos, avaliando-se matematicamente as funções de transferência de cada um dos circuitos
através do Matlab e verificando-se o comportamento eletrónico esperado de cada uma destas funções de transferência, traduzidas em circuitos constituídos por resistências, condensadores, díodos, amplificadores operacionais (AmpOp’s), junction field effect transistor (JFET) e transístores bipolares de junção (TBJ), através da ferramenta tecnológica ORCaD PSpice. Verificada a compatibilidade de resultados em ambiente de simulação face aos resultados esperados teoricamente, implementa-se fisicamente o circuito descrito e
implementado no software de simulação, realizando-se uma comparação direta entre os resultados obtidos em simulação e experimentalmente, avaliando-se a fiabilidade e qualidade dos resultados obtidos.
In everyday life, it’s common to use audio electronic systems to carry out all phases of transmission, reception, configuration and exposure of sound waves. In this context, this project implements analog audio electronic systems that allow the controlled reception of a sound signal, leveling it to a pre-defined amplitude, but manually changeable, with the aim of providing the user with a volume experience sound, independent of the amplitude variations of the signal at the system’s input. Furthermore, a sound configuration circuit is developed that allows the amount of sound volume amplification to be varied actively through Baxandall's active volume control (CAV), which is placed in series with a sound wave quality improvement circuit to be transmitted to the output, through the filtering of electromagnetic frequencies harmful to the formation of a sound signal, that is, outside the frequency band between 20 Hertz (Hz) and 20 kilo-Hertz (103 Hz, or, kHz). Additionally, a 4-band graphic equalizer is designed and implemented, with central frequencies of 250 Hz, 1 kHz, 4 kHz and 16 kHz, where each band is performed electronically through octave band pass filters, with the fundamental manipulation frequency set to those idealized and referred to above. This circuit allows the influence in amplitude of each frequency to be individually changed, allowing the user the ability to perceive the spectral configuration most appropriate to his taste. Throughout the development of the report, it is stated that an advantage of the circuits developed is the cost associated with the construction of each one of them, since in order to carry out the transfer functions described, the circuits cost less than ten euro. On the other hand, the difficulty of implementation and the lack of versatility of the circuits are seen as disadvantages of the analog solutions idealized for the implementatino of the functionalities intended for voice and audio capture and configuration systems. As a method of evaluating the solutions idealized for the project, the technological tools Matlab and ORCaD PSpice are used to computationally verify the theoretical dimensioning developed for each circuit, mathematically evaluating the transfer functions of each of the circuits using Matlab, and verifying the expected electronic behavior of each of these transfer functions, translated into circuits made up of resistors, capacitors, diodes, operational amplifiers (AmpOp's), junction field effect transistor (JFET) and bipolar junction transistors (TBJ ), through the ORCaD PSpice technological tool. Once the compatibility of results in the simulation environment has been verified in relation to the theoretically expected results, the circuit described and implemented in the simulation software is physically implemented, making a direct comparison between the results obtained in simulation and experimentally, evaluating the reliability and quality of the results obtained.
In everyday life, it’s common to use audio electronic systems to carry out all phases of transmission, reception, configuration and exposure of sound waves. In this context, this project implements analog audio electronic systems that allow the controlled reception of a sound signal, leveling it to a pre-defined amplitude, but manually changeable, with the aim of providing the user with a volume experience sound, independent of the amplitude variations of the signal at the system’s input. Furthermore, a sound configuration circuit is developed that allows the amount of sound volume amplification to be varied actively through Baxandall's active volume control (CAV), which is placed in series with a sound wave quality improvement circuit to be transmitted to the output, through the filtering of electromagnetic frequencies harmful to the formation of a sound signal, that is, outside the frequency band between 20 Hertz (Hz) and 20 kilo-Hertz (103 Hz, or, kHz). Additionally, a 4-band graphic equalizer is designed and implemented, with central frequencies of 250 Hz, 1 kHz, 4 kHz and 16 kHz, where each band is performed electronically through octave band pass filters, with the fundamental manipulation frequency set to those idealized and referred to above. This circuit allows the influence in amplitude of each frequency to be individually changed, allowing the user the ability to perceive the spectral configuration most appropriate to his taste. Throughout the development of the report, it is stated that an advantage of the circuits developed is the cost associated with the construction of each one of them, since in order to carry out the transfer functions described, the circuits cost less than ten euro. On the other hand, the difficulty of implementation and the lack of versatility of the circuits are seen as disadvantages of the analog solutions idealized for the implementatino of the functionalities intended for voice and audio capture and configuration systems. As a method of evaluating the solutions idealized for the project, the technological tools Matlab and ORCaD PSpice are used to computationally verify the theoretical dimensioning developed for each circuit, mathematically evaluating the transfer functions of each of the circuits using Matlab, and verifying the expected electronic behavior of each of these transfer functions, translated into circuits made up of resistors, capacitors, diodes, operational amplifiers (AmpOp's), junction field effect transistor (JFET) and bipolar junction transistors (TBJ ), through the ORCaD PSpice technological tool. Once the compatibility of results in the simulation environment has been verified in relation to the theoretically expected results, the circuit described and implemented in the simulation software is physically implemented, making a direct comparison between the results obtained in simulation and experimentally, evaluating the reliability and quality of the results obtained.
Description
Keywords
Amplitude Frequency Sound wave Sound spectrum Amplification Attenuation Gain Bandpass filter Automatic gain control (CAG) Active volume control (CAV) RF filter Graphic equalizer Amplitude Frequência Onda sonora Espetro sonoro Amplificação Atenuação Ganho Filtro passa-banda Controlo ativo de volume (CAV) controlo automático de ganho (CAG) Filtro RF Equalizador gráfico