modem
The digital signals is not converted BACK to analog! it is transmitted in digital form and the receiver is converting it back to analog to drive the speakers. The signal from the microphone is converted from analog to digital with an A/D converter chip, digital signals consist of pulses of different lengths that is switching the transmitter on and off in about the same way as the old Morse code transmissions but at a much higher rate (millions of times higher)
No, some electronic devices use analog signals as their input/output others may use digital signals as their input/output; some equipment uses an analog signal as the input and outputs a digital signal. Be sure to use the correct signal and signal strength otherwise you may damage your electronic device.
TV converter boxes are used to convert signals which cannot be understood by your TV into a signal which can be understood. A common use is to translate analog signals into digital ones.
digital signals have two values. 0 and 1.
Digital signals are measured in bits per second (bps).
Analogue signals are more vulnerable to error than digital signals. See the related question "Why digital signals are more noise free than analogue signals?" for more details.
Digital signals are measured in bits per second (bps).
modem is the device that carries digital signals
To measure time between digital signals.
Digital signals
it is an DAC (Digital to analogue converter
digital video camera