Linked from
The 16 pages that link to Digital signal, each with the reason it gives.
Logic gateRelated: Logic gates process digital signals rather than continuously varying values.
BitRelated: Digital systems encode bit values as distinguishable signal states.
DigitizationRelated: Digitized measurements are commonly carried or stored as digital signals.
Digital audio broadcastingRelated: DAB sends program information in digitally represented form.
Digital dataRelated: Devices convey digital data as signals with distinguishable states.