Design Components
Ultrasound Data Acquisition There are four main components the project design: ultrasound data collection, A/D conversion, FPGA, and Data transfer via Bluetooth. First of all, ultrasound analog (raw data) collection must be done differently from original model. The fetal heart rate sound is around 35-110 Hz. This is a weak and low frequency vibration. As the vibration frequency is quite weak it can be easily contaminated with surrounding noise, such as various maternal organ sounds, fetal movement effect, shear noise, etc. Thus, the sound must use an amplitude modulation to amplify and filter the signal to produce a clean signal. Nevertheless, a wireless signal producer is used, which it produces noise signals while transferring data. Depending on the size and frequency nature, it may interfere with the FHR analog data that is produced by the transducer. Even with a regular ultrasound transducer the signal must be amplified and filtered with careful considerations. Therefore, the original data amplitude modulation must modified to produce clean and clear FHR signal data.
A/D Converter In order to send data from the sensor to the recorder, we need to convert analog data into digital data so that this resulting ultrasound is converted into digital numbers which are then sent to the recording devices using Bluetooth Low Energy(BLE). Fortunately, the resulting signal is 1-D low resolution and thus its size is relatively very small compare to other ultrasound images that have very high resolution with 3-D images(actual output equals to about 200Mbps~300Mbps). Thus, this resulting signal can be transferred by BLE. However, before using BLE technology to transfer the data, each sample’s actual output data rate equals about 300Kbps- necessitating the use of an FPGA with LVDS to buffer data.
FPGA The Altera Cyclone III is a powerful Field-Programmable Gate Array (FPGA) featuring 10,320 Logic Elements and the communication protocol with the FHR monitor using BLE is discussed later in the paper.
Bluetooth Low Energy Communication Bluetooth low energy(BLE) is designed as low-power consumption version of Bluetooth. It also operates in the 2.4 GHz band and features a bandwidth of 1 Mbpswith a range of 30 m. It is extremely power-efficient, as BLE uses maximum of 15mA and the average power consumption of 1uA. Even more, the power consumption is kept low for the most of the time as its connection time is only about few ms. To make this more portable than the existing fetal heart rate monitor in market, BLE met all its satisfactions; relatively high transferring data rate, very low power consumption, and security issues, etc.
At the end, the digitalized data will be shown in FHR monitor. With further implications, the data can also be transferred to the other monitoring devices, including other monitors, computers and even smartphones. This wireless ways of transmitting images between the sensor and the recorder will greatly increase the portability of the existing fetal heart rate monitor on the market.
A/D Converter In order to send data from the sensor to the recorder, we need to convert analog data into digital data so that this resulting ultrasound is converted into digital numbers which are then sent to the recording devices using Bluetooth Low Energy(BLE). Fortunately, the resulting signal is 1-D low resolution and thus its size is relatively very small compare to other ultrasound images that have very high resolution with 3-D images(actual output equals to about 200Mbps~300Mbps). Thus, this resulting signal can be transferred by BLE. However, before using BLE technology to transfer the data, each sample’s actual output data rate equals about 300Kbps- necessitating the use of an FPGA with LVDS to buffer data.
FPGA The Altera Cyclone III is a powerful Field-Programmable Gate Array (FPGA) featuring 10,320 Logic Elements and the communication protocol with the FHR monitor using BLE is discussed later in the paper.
Bluetooth Low Energy Communication Bluetooth low energy(BLE) is designed as low-power consumption version of Bluetooth. It also operates in the 2.4 GHz band and features a bandwidth of 1 Mbpswith a range of 30 m. It is extremely power-efficient, as BLE uses maximum of 15mA and the average power consumption of 1uA. Even more, the power consumption is kept low for the most of the time as its connection time is only about few ms. To make this more portable than the existing fetal heart rate monitor in market, BLE met all its satisfactions; relatively high transferring data rate, very low power consumption, and security issues, etc.
At the end, the digitalized data will be shown in FHR monitor. With further implications, the data can also be transferred to the other monitoring devices, including other monitors, computers and even smartphones. This wireless ways of transmitting images between the sensor and the recorder will greatly increase the portability of the existing fetal heart rate monitor on the market.