Single sideband transparent tone in band for trunked mobile radio

The use of mobile radio has become more widespread, resulting in increased pressure on the spectrum allocated for use by mobile services. The transition from 25 kHz to 12.5 kHz channel spacing provided a significant increase in the number of available channels and the introduction of trunked radio systems has enabled the available channels to be used by a greater number of users. However, even with these improvements, the pressure on the spectrum still remains and methods for accommodating a larger number of users in a given bandwidth are still required. It has been suggested that single sideband (SSB) transmissions can be used for mobile radio in 5 kHz channels using a transparent tone in band (TTIB). The author discusses TTIB and then describes the trials of SSB TTIB conducted by Bradford University with Securicor Communications. In particular the author discusses voice tests. The implications for the future of SSB TTIB in trunked systems and TTIB specification are also discussed.<>