This document describes the design of a digital voice recorder. It includes specifications for input audio processing using an amplifier and filter to clean noise from voice signals. It also describes the processor operation using an Arduino Uno, audio buffering, storage on an SD card using a library, and output audio processing using DAC, PWM, and an LM386 amplifier circuit. Overall, the design aims to amplify and filter voice input, digitally process and store audio on an SD card, and output clean amplified audio.
The acoustic properties of a room design should ensure that it is easy to both speak and listen with a high degree of intelligibility. Reverberation Time is the single most important parameter used to evaluate room acoustics.
Introducing the Icom IC-7300 HF/50/70MHz TranscieverIcom UK Ltd
This presentation gives simple bulleted points about Icom's IC-7300.
The IC-7300 is a revolutionary compact radio that will excite HF operators from beginners to experts. This new model has a high-performance real-time spectrum scope and employs a new RF direct sampling system. The IC-7300’s real-time spectrum scope provides top-level performance in resolution, sweep speed and dynamic range. While listening to received audio, the operator can check the real-time spectrum scope and quickly move to the intended signal. The combination of the real-time spectrum scope and waterfall function improves the quality and efficiency of HF operation.
The new RF direct sampling system employed by the IC-7300 realises class leading RMDR (Reciprocal Mixing Dynamic Range) and Phase Noise characteristics. In addition, the IC-7300 features the 70MHz band (European versions only), a large touch screen colour TFT LCD, convenient multi-function dial knob, automatic antenna tuner, voice recorder function and more.
For more details about this radio, visit http://icomuk.co.uk/IC-7300/Amateur_Radio_Ham_Base_Stations
Producers of almost any kind of machinery or devices are required by regulations, e.g. the Noise and machinery directive of EU (2006/42/EC), to measure and declare the sound power of their products - anything from toys, printers and white goods to industrial tools and construction machinery. Sound Power is also used in engineering tasks such as product sound design.
openGear is an open-architecture rack system developed by Ross Video, to provide a standard rack-based platform on which companies can develop card-based audio & video products. The adoption of openGear based cards by Sonifex allows customers to choose Sonifex cards as part of an overall terminal equipment solution. The openGear frames offer the flexibility of independent rear modules for connectivity to a wide array of interfaces and control via TCP/IP connectivity using a free application called Dashboard.
The acoustic properties of a room design should ensure that it is easy to both speak and listen with a high degree of intelligibility. Reverberation Time is the single most important parameter used to evaluate room acoustics.
Introducing the Icom IC-7300 HF/50/70MHz TranscieverIcom UK Ltd
This presentation gives simple bulleted points about Icom's IC-7300.
The IC-7300 is a revolutionary compact radio that will excite HF operators from beginners to experts. This new model has a high-performance real-time spectrum scope and employs a new RF direct sampling system. The IC-7300’s real-time spectrum scope provides top-level performance in resolution, sweep speed and dynamic range. While listening to received audio, the operator can check the real-time spectrum scope and quickly move to the intended signal. The combination of the real-time spectrum scope and waterfall function improves the quality and efficiency of HF operation.
The new RF direct sampling system employed by the IC-7300 realises class leading RMDR (Reciprocal Mixing Dynamic Range) and Phase Noise characteristics. In addition, the IC-7300 features the 70MHz band (European versions only), a large touch screen colour TFT LCD, convenient multi-function dial knob, automatic antenna tuner, voice recorder function and more.
For more details about this radio, visit http://icomuk.co.uk/IC-7300/Amateur_Radio_Ham_Base_Stations
Producers of almost any kind of machinery or devices are required by regulations, e.g. the Noise and machinery directive of EU (2006/42/EC), to measure and declare the sound power of their products - anything from toys, printers and white goods to industrial tools and construction machinery. Sound Power is also used in engineering tasks such as product sound design.
openGear is an open-architecture rack system developed by Ross Video, to provide a standard rack-based platform on which companies can develop card-based audio & video products. The adoption of openGear based cards by Sonifex allows customers to choose Sonifex cards as part of an overall terminal equipment solution. The openGear frames offer the flexibility of independent rear modules for connectivity to a wide array of interfaces and control via TCP/IP connectivity using a free application called Dashboard.
• G7 Wireless Sensor System provides online monitoring of wireless temperature and humidity sensors over Ethernet network. Wireless sensor transmits measurement to Base Station via wireless RF signal.
• Connect up to 64 wireless sensors either temperature or humidity; Temperature sensor probe Base Station uploads data to central over Ethernet in an industrial standard Modbus TCP protocol.
• G7 Wireless Client Lite for Windows allows user to receive the data directly from Base Station and save into local storage.
• G7 provides easy installation, configuration and flexible expandability of temperature humidity monitoring in factory, food chain, supermarket, cold food storage and industrial plant.
• G7 Wireless Sensor System provides online monitoring of wireless temperature and humidity sensors over Ethernet network. Wireless sensor transmits measurement to Base Station via wireless RF signal.
• Connect up to 64 wireless sensors either temperature or humidity; Temperature sensor probe Base Station uploads data to central over Ethernet in an industrial standard Modbus TCP protocol.
• G7 Wireless Client Lite for Windows allows user to receive the data directly from Base Station and save into local storage.
• G7 provides easy installation, configuration and flexible expandability of temperature humidity monitoring in factory, food chain, supermarket, cold food storage and industrial plant.
Discussion of some of the predicted advances in the coming years in software defined radio (SDR) in the amateur radio market. Also are some insights in how radios are designed.
4. Input: Amplification & Filter
● In order to perform digital operations an analog signal must be converted into corresponding
digital output using Analog to Digital Converter (ADC).
● However, the noise outside of the band of interest makes the digital conversion a problem
due to unwanted added component
● Moreover, the low input signal (voice) must be amplified
● Design: An input amplifier with Filter topology is used to clean up incoming voice signal and
prepare it for processing.
5. Input System Design:
● In this project, the audio signal recorded by microphone is used for
amplification and filtering.
● Sound signal is within 0-20 kHz. A filter of 20kHz cutoff frequency is designed.
6. Input Circuit:
● System must perform two functions:
○ DC Shift of 2.5V: A non-inverting amplification
○ 40dB amplification with 20kHz cut-off frequency: A inverting amplification with RC
based filter at feedback of the amplifier.
14. SD Library
●SD library reads the data from the SD card, and write
to the SD card.
●SPI library is needed to communicate the arduino with
the shield.
●The data is written as a wav file where every block
contains some number of bits.
16. DAC
●Digital signals coming from arduino will be converted
into analog signal.
●A Buffer amplifier to protect the signal.
●Low pass filter to reduce the noise.
●Huge capacitor for better quality sound.
17. DAC vs PWM
●DAC will not give space to obtain the data from the SD
card.
●PWM is the solution to get enough space for the SD
card to do its functionality.
22. WHY LM386 ?
1) Quiescent power architecture which allows the unit to consume very little power (about 24mW)
when the device speaker is not in use
2) Easy gain control through the change of a single external capacitor
3) Cheaper, smaller and more effective option compared discreetly driven transistor based circuits
that require more components
4) Built-in large input resistance to prevent over current flow