The main problems with the old analogue cordless phones were interference from other cordless phones and the fact you could eavesdrop using a similar phone or baby monitor on the same frequency. The new digital cordless phones solved these problems by rapidly hopping through a range of frequencies. But this rapid hopping coarsens speech quality. So telecoms company Siemens suggests a compromise (WO 02054616).
Siemens’s new digital cordless phone continually monitors the airwaves to check which are in use or suffering interference. It then hops only between whichever frequencies are clear. So the hops are slower and the phone can stay on one frequency for…
