It's neat, but practically speaking having a transmit only device isn't useful for GSM. Having to use filtering on the output is also a major pain.
It is perhaps more interesting for use as a data exfiltration technique. Simple devices, usually used without analysis, can punch out a signal which is easily decoded, with a simple (and seemingly accidental) antenna.
It is perhaps more interesting for use as a data exfiltration technique. Simple devices, usually used without analysis, can punch out a signal which is easily decoded, with a simple (and seemingly accidental) antenna.