title: A simple microcontroller based digital lock-in amplifier for the detection of low level optical signals

authors: Dorrington, Adrian A.

subjects: digital lock-in amplifier

abstract: Traditionally digital lock-in amplifiers sample the input signal at a rate much higher than the lock-in reference frequency and perform the lock-in algorithm with high-speed processors. We present a small and simple digital lock-in amplifier that uses a 20 bit current integrating analogue-to-digital converter interfaced to a microcontroller. The sample rate is set to twice the reference frequency placing the sampled lock-in signal at the Niquest frequency allowing the lock-in procedure to be performed with one simple algorithm. This algorithm consists of a spectral inversion technique integrated into a highly optimised low-pass filter. We demonstrate a system with a dynamic range of 103dB recovering signals up to 85dB below the interference.

text: A simple microcontroller based digital lock-in amplifier for the detection of low level optical signals Traditionally digital lock-in amplifiers sample the input signal at a rate much higher than the lock-in reference frequency and perform the lock-in algorithm with high-speed processors. We present a small and simple digital lock-in amplifier that uses a 20 bit current integrating analogue-to-digital converter interfaced to a microcontroller. The sample rate is set to twice the reference frequency placing the sampled lock-in signal at the Niquest frequency allowing the lock-in procedure to be performed with one simple algorithm. This algorithm consists of a spectral inversion technique integrated into a highly optimised low-pass filter. We demonstrate a system with a dynamic range of 103dB recovering signals up to 85dB below the interference.

year: 2002

title: Young women's negotiation of multiple fields of femininity and physicality in physical activity and Physical Education in an international school in Taiwan

authors: Thomas, Melissa Maree

subjects: physical activity

abstract: Gender research over the past three decades has emphasised the socially constructed nature of experience in physical activity. Numerous studies have explored the influence of cultural, social, economic and political influences on young women's understandings of their bodies, physical activity, sport and physical education, although this research is limited to a focus on the western context. As a New Zealand physical education teacher in an international school in Taiwan, I set out to investigate the physical activity experiences of young women attending this school and the associated implications for teaching physical education. My study involved a focus group and in-depth interviews with four young women. I adopted a Bourdieudian approach in my data analysis in order to investigate ways in which the young women negotiated norms, rules, practices and expectations of femininity and physicality within and across multiple fields. A significant presence of an 'Asian mindset' was highlighted, which presented a focus on academic achievement and traditional Taiwanese forms of appropriate femininity and physicality. Resulting valuation systems often conflicted with those present in the physical education class. The findings revealed young women negotiated these value systems through various means. Some chose to accept and embody these values limiting their engagement in physical education, while other young women were empowered to challenge them, enhancing their engagement in physical education. This study contributes to gender and physical education research as it offers a perspective of the diverse nature of young women's experiences in physical activity within a non-western context.

text: Young women's negotiation of multiple fields of femininity and physicality in physical activity and Physical Education in an international school in Taiwan Gender research over the past three decades has emphasised the socially constructed nature of experience in physical activity. Numerous studies have explored the influence of cultural, social, economic and political influences on young women's understandings of their bodies, physical activity, sport and physical education, although this research is limited to a focus on the western context. As a New Zealand physical education teacher in an international school in Taiwan, I set out to investigate the physical activity experiences of young women attending this school and the associated implications for teaching physical education. My study involved a focus group and in-depth interviews with four young women. I adopted a Bourdieudian approach in my data analysis in order to investigate ways in which the young women negotiated norms, rules, practices and expectations of femininity and physicality within and across multiple fields. A significant presence of an 'Asian mindset' was highlighted, which presented a focus on academic achievement and traditional Taiwanese forms of appropriate femininity and physicality. Resulting valuation systems often conflicted with those present in the physical education class. The findings revealed young women negotiated these value systems through various means. Some chose to accept and embody these values limiting their engagement in physical education, while other young women were empowered to challenge them, enhancing their engagement in physical education. This study contributes to gender and physical education research as it offers a perspective of the diverse nature of young women's experiences in physical activity within a non-western context.

year: 2009

title: Technology, culture and location in a recent New Zealand sonic art project

authors: Whalley, Ian

subjects: music

abstract: The HIEMPA (Hybrid Instruments from Electroacoustic Manipulation And Models of Pütorino and Aquascape) project combined a team of people with technical, artistic, environmental and cultural expertise toward the artistic outcome of extending the New Zealand sonic art tradition. The project involved collecting audio samples from the aquascape of the Ruakuri Caves and Nature Reserve in Waitomo, South Waikato, New Zealand; and samples of a variety of Pütorino – a New Zealand Mäori wind instrument. Following a machine learning analysis of this audio material and an analysis of the performance material, hybrid digital instruments were built and mapped to suitable hardware triggers. The new instruments are playable in real-time, along with the electroacoustic manipulation of Pütorino performances. The project takes into account the environmental and cultural significance of the source material, with the results to be released as a set of compositions. This paper discusses the research process.

text: Technology, culture and location in a recent New Zealand sonic art project The HIEMPA (Hybrid Instruments from Electroacoustic Manipulation And Models of Pütorino and Aquascape) project combined a team of people with technical, artistic, environmental and cultural expertise toward the artistic outcome of extending the New Zealand sonic art tradition. The project involved collecting audio samples from the aquascape of the Ruakuri Caves and Nature Reserve in Waitomo, South Waikato, New Zealand; and samples of a variety of Pütorino – a New Zealand Mäori wind instrument. Following a machine learning analysis of this audio material and an analysis of the performance material, hybrid digital instruments were built and mapped to suitable hardware triggers. The new instruments are playable in real-time, along with the electroacoustic manipulation of Pütorino performances. The project takes into account the environmental and cultural significance of the source material, with the results to be released as a set of compositions. This paper discusses the research process.

year: 2008