Enhanced wireless communication for medical devices
Methods and apparatuses for wireless communication between medical devices are provided. In some embodiments, commodity low power, low bandwidth communication protocols may be utilized to simultaneously convey multiple signals with high fidelity and reliability. For example, cardiac sound data and ECG data may be compressed using a common ADPCM component and inserted into a common BLE packet structure. Command-control data may also be inserted. Where required command-control data reporting frequency is less than the packet frequency, header bits may be utilized to convey multiple types of command-control data in a given packet byte position. Rolling packet sequence values may be inserted into the common packet structure, for use by receiving devices to identify link integrity failures.
1. A method for transmitting cardiac data from a wireless sensor to a host device, the method comprising:
digitizing cardiac sound data and ECG data received at the wireless sensor;
filtering the digitized cardiac sound data and ECG data;
compressing the cardiac sound data and the ECG data using an adaptive differential compression component;
combining the compressed cardiac sound data and compressed ECG data into a common packet structure; and
transmitting the common packet structure from the wireless sensor to the host device via a Bluetooth Low Energy communications link.
2. The method of claim 1 , in which the step of compressing the cardiac sound data and ECG data comprises applying both the cardiac sound data and the ECG data to a common adaptive differential pulse code modulation encoder.
3. The method of claim 2 , in which the ECG data has a sample rate of approximately 500 Hz.
4. The method of claim 3 , in which the cardiac sound data has a sample rate of approximately 4 kHz.
5. The method of claim 4 , in which the step of filtering the digitized cardiac sound data comprises applying a digital lowpass filter to attenuate frequency components above 2 kHz.
6. The method of claim 1 , in which the step of combining the compressed cardiac sound data and compressed ECG data into a common packet structure further comprises inserting command-control data into the common packet structure.
7. The method of claim 6 , in which the command-control data has a reporting frequency lower than the packet frequency, wherein the step of inserting command-control data into the common packet structure comprises inserting a command-control comprising a command-control value and a header value, the header value indicative of a content type with which the command-control value is associated.
8. The method of claim 1 , in which the step of combining the compressed cardiac sound data and compressed ECG data into a common packet structure further comprises inserting a rolling packet sequence value into the common packet structure.
9. The method of claim 8 , in which the rolling packet sequence value is four bits in length.
10. The method of claim 8 , further comprising:
receiving by the host device sequential data packets having non-sequential rolling packet sequence values; and
displaying a warning indicia on a host device user interface.