31 January 2014

Musings about going Bluetooth

I occasionally receive a question about transporting bidirectional audio over Bluetooth and not only CAT controls. The answer is "technically possible", but there are two possible scenarios.


This is the case for handsfree operation, be it in on the move or just around the house. Using the VOX this is possible, but on the RTX side we need a Bluetooth "master" device. In order to establish a Bluetooth link there must be a master initiating the connection towards a slave. Since all in-ear handsfree earphones are "slaves", there is need for a master device connected to the transceiver: I have not found yet a master bidirectional audio Bluetooth module (maybe the one mentioned in an earlier post?!).
The discontinued Jabra A210 seems to be the only device with such characteristics, and it must be modified in order to work with a transceiver.


Since digimodes are generated in the computer/tablet/smartphone, we already have a master Bluetooth device. So theoretically any handsfree BT earphone would work. Besides difficulties in modifying such tiny electronics, I have been told that the audio encoding and compression operated by BT audio devices introduces unacceptable noise and phase distortion. The former affects the ability to copy weak signals at our antenna, the latter makes it impossible to work phase-based digital modes (PSK31, for example, while RTTY would probably work).