The Trimode Dwell time of 4 seconds , is the 'only' limiting factor , preventing the deployment of SDR in a gateway
which is perhaps a legacy issue ..
Unlike 'fixed'/'static' timed systems / protocols , Processing delays and switching times are not critical, the Vara modem deploys 'Dynamic' timing , additional delays [symmetrical & asymmetrical]
are automatically compensated for . eg repeater delays for VHF/FM and the long path delay , for the AO-100 Sat link version [ which also can be used for HF etc ] , leaving the HF version, while compatible with the 4 second dwell requirement ,unable to provided otherwise, sdr<>sdr connectivity
The limiting factor is solely the 4 seconds delay , [as to why '4' seconds is required
is not clear ?] .
Increasing the Dwell time by 500mS , to 4.5 seconds , would allow deployment of the Vara HF
modem , inside the Trimode system and provide both SDR<>SDR and Hybrid connectivity
both inside and out side the winlink system.