gr-osmosdr's source and sink blocks have operations to retrieve information about the capabilities of a device, such as the range of its frequency setting and the existence and valid ranges of its gain settings. Unfortunately, in the case of a sink (transmitter driver), creating the sink block itself starts transmission, meaning that it is not possible to create interactive UI for the sink until the first transmission.
(At least, that's the behavior when using a HackRF device. If the behavior is different on other devices, then it should be brought into line since gr-osmosdr is supposed to be an adapter.)
This is closely related to the problem of supporting half duplex operation which I filed HackRF-specifically at mossmann/hackrf#195. In that thread, it was suggested that the sink should simply do nothing until it receives a tx_sob tag.
(How this should be made compatible with existing users of the sink, I don't know.)
gr-osmosdr's source and sink blocks have operations to retrieve information about the capabilities of a device, such as the range of its frequency setting and the existence and valid ranges of its gain settings. Unfortunately, in the case of a sink (transmitter driver), creating the sink block itself starts transmission, meaning that it is not possible to create interactive UI for the sink until the first transmission.(At least, that's the behavior when using a HackRF device. If the behavior is different on other devices, then it should be brought into line since gr-osmosdr is supposed to be an adapter.)
This is closely related to the problem of supporting half duplex operation which I filed HackRF-specifically at mossmann/hackrf#195. In that thread, it was suggested that the sink should simply do nothing until it receives a tx_sob tag.
(How this should be made compatible with existing users of the sink, I don't know.)