0
How can you use an analog telephone signal to activate a digital relay?
Wiki User
∙ 10y ago
There are many different ways this could be done depending on the purpose and exactly which analog telephone signal is to be used.
- ring signal, this is a 120VAC 5Hz pulsed signal present between tip & ring when the phone is on hook and being called; a high voltage insulated optocoupler must be used to trigger a oneshot or flipflop that will control a relay driver to operate the relay
- on/off hook switching, when on hook 48VDC is present between tip & ring, when off hook this voltage drops below about 10VDC; these states are probably best sensed using a level detector on a floating power supply (to protect against damage by the ring signal) and a high voltage insulated optocoupler must be used to control a relay driver to operate the relay
- AF tone signal, this is a signal somewhere between 50Hz and 3KHz; a 600 ohm to 600 ohm transformer should be used to block the ring signal and DC on/off hook voltages, this transformer should drive an amplifier (and maybe a clipper) the output of which goes to one or more phase locked loops set to specific frequencies, the phase locked loop outputs each control separate relay drivers to operate the relays
Note: these are not the only way to accomplish this, in fact commercial off the shelf phone interface modules are available that will handle the ring and hook signals for you (maybe even including the relay drivers or even actual relays) and provide the AF signal ready to feed to the phase locked loops. Such modules may actually be the best way to start if you don't want to run the risk of a mistake that might cause the phone company to disconnect service for a detected fault that could damage their equipment.
Wiki User
∙ 10y ago
Add your answer:
Earn +20 pts
What is it called when you convert a digital signal to analog?
When you convert digital signal to analog, it is called as an analog signal. The device used is called digital to analog converter.
What is convert analog to digital convert?
An analog-to-digital converter is a device which converts an infinite resolution analog signal to a finite resolution digital signal.
What is the best signal processing either a analog signal processing?
Digital signal processing is the best compared to analog signal. It is because the digital signal is moreefficienterror freeimmune to noisethan an analog signal
Differentiate between an analog and a digital electromagnetic signal?
1. Digital Signal is non-continuous signal where as analog is continuous signal 2. Digital signal contain only two value that is 0 or 1,or high or low where as analog contain all the values in it's time interval 3.Chance of attenuation in analog is more then digital signal
What are the differences between analog and digital transistors?
transducer convert one energy to other energy .now in analog transducer it convert energy use of analog signal and digital it converts use og digital signal
Meaning of modem?
Modem in fact acts as an interpreter. When computer exchanges datas with other computers in internet,it has to take the assistance of telephone. But computer understands digital signal whereas telephone analog signal. For making reconciliation between the two requires one interpreter who can convert analog to digital and digital to analog. Modem's activity is to convert analog signal from telephone to digital understood by computer and vice verse.
Why do you use modem?
modem means modulator demodulator. it converts digital signal to analog signal. it is use to transmit computer signal (digital signal) over the telephone line to communicate to other computers. modem converts the computer digital signal into frequency (analog signal) so that it can transmit over the telephone line and at the receiving end the modem converts the analog signal back to digital for the receiving computer to understand it.
What converts a message from digital to analog and analog to digital?
An DAC convert digital signal to analog signal i.e Digital to Analog Converter. An ADC convert analog signal to digital signal i.e Analog to Digital Converter.
When you call to telephone voice is analog where digital signal conversion occured inside the telephone set or in the PSTN?
Digital signal conversion is done on the telephone unit itself. Whether it is a call forwarding service or not.
What is it called when you convert a digital signal to analog?
When you convert digital signal to analog, it is called as an analog signal. The device used is called digital to analog converter.
What is encoding technique?
There are four possible combinations of encoding techniques -Digital data, digital signal -Digital data, analog signal -Analog data, digital signal -Analog data, analog signal
Why is a modem needed for analog telephone lines?
A modem (which stands for Modulator-Demodulator) converts digital data from the computer to analog data compatible with the telephone system. The analog signal is converted back into digital data on the other end of the call.
What are basic elements of digital signal processing?
The basic elements in digital signal processing are an analog to digital converter, digital signal processor, and digital to analog converter. This process can take an analog input signal, convert it to digital for processing and offer an analog output.
A telephone signal is digitized to reduce noise what type of conversion does this represent?
Analog-to-digital conversion
Where should analog to digital converter be placed?
where an analog signal is to be converted into digital signal,because in some applications we need digital signal where we have analog signal that is we use an A/D converter
What is an analog-to-digital converter?
An analog-to-digital converter is a device which converts an infinite resolution analog signal to a finite resolution digital signal.
How information is transmitted?
by analog to digital,digital to analog signal
