Communication
Description of the context
We will discuss and evaluate the best way to exchange data between probe and mobile application.
the nature of the data stream is:
raw images are streamed to the mobile application with 10 - 15 FPS
probe battery status is regularly sent to mobile application
user acquisition settings changes on mobile application have to be dispatch to the probe ie frequency change, TGC change ...
(optionnal) user triggered events on probe ie screen capture
Existing solutions
| Bandwidth | pairing | security | robustness | range | protocol | maturity of technology | autonomy / energy consumption | real-time ? | cost | transfer frequency spectrum | comments | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| USB 2.0 OTG communication | 280 Mb/s | instantaneous | / | - wire robustness | length of the cable | TCP, Series, audio protocol - check android compatibility | battle tested | / | yes | 1 $ | / | wired, reglementation ? |
| Wifi - infrastructure | very unstable | manual the first time. very complex for the probe to connect | SSL / TLS - standard | very unstable | 200m | TCP | battle tested | 10+ hours | yes | < 10$ | 2,4 GHz | |
| Wifi - point to point - websocket | 100 Mb/s theorical | manual, automatic with tag NFC ? - https://stackoverflow.com/questions/2140133/how-and-what-to-set-to-android-wificonfiguration-presharedkey-to-connect-to-the | SSL / TLS - standard | resilient | 200m | TCP | battle tested | 10+ hours | yes - GoPro stream to mobile app | < 10$ | 2,4GHz | no sharing, no internet connection |
| Bluetooth LE | on field - 800kb/s | almost automatic | security 3 levels - LMP protocol | medium | 30m | Series, LE, AD2P, see incomming video protocol | battle tested | see headset autonomy | ok | <10$ | 2,4GHz | |
| Bluetooth Classic 3.0 - SPP | on field - 800kb/s | pairing delay ~ 20 seconds | security 3 levels - LMP protocol | medium | 30m | Series, LE, AD2P, see incomming video protocol | unknown | see headset autonomy | ok | < 10 $ | 2,4 GHz | |
| Bluetooth Classic 3.0 - High speed | theorically - 24 Mb/s | pairing delay ~ 20 seconds | security 3 levels - LMP protocol | medium | 30m | Series, LE, AD2P, see incomming video protocol | battle tested | see headset autonomy | ok | < 10$ | 2,4 GHz | to be challenged, no apparent use |
| Bluetooth 5.0 | on field - 1,4Mb/s | almost automatic | security 3 levels - LMP protocol | medium | 30m | Series, LE, AD2P, see incomming video protocol | battle tested | see headset autonomy | ok | < 10$ | 2,4 GHz | / |
We could explore also home made radio communication with dongle on smartphone.
What is done on similar devices
GE Healthcare VScan probe is wired to the smartphone
Clarius Imaging supports devices with Wi-Fi 802.11n and BLE 4.1
Philips Lumify probe is wired to the smartphone
Butterfly IQ probe is wired to the smartphone
Discussion
- investigate Wifi pairing
- implementation software for TCP protocol on Wifi
- implementation software to stream with TCP protocol on USB