Want hlp in dsigning of a binary ASK modem or Power Line Modem. I have a project of designing a binary ASK modem, with a microphone as an input and a speaker as an output.
Mail from AM UK
Study these links ....
Amplitude-shift keying (ASK)
Amplitude-shift keying (ASK) is a form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave. In an ASK system, the binary symbol 1 is represented by transmitting a fixed-amplitude carrier wave and fixed frequency for a bit duration of T seconds. If the signal value is 1 then the carrier signal will be transmitted; otherwise, a signal value of 0 will be transmitted.
OFDM-Based Power Line Communication Modem
"The MAX2990 power line communication (PLC) baseband modem delivers a cost-effective, reliable, half-duplex asynchronous data communication over AC or DC power lines at speeds up to 100kbps. The MAX2990 is a highly integrated system-on-chip (SoC) that combines the physical (PHY) and media access control (MAC) layers using Maxim's 16-bit MAXQ microcontroller core. The MAX2990 utilizes OFDM modulation techniques to enable robust data communication using the same electrical network that supplies power to all other devices on the network."
LEDs Allow New Remote-Controlled Lighting Applications
PLC technology allows communication over a long range. New OFDM-based PLC technology, including emerging standards such as G3-PLC™, is simplifying integration of lighting control applications by providing noise immunity and interoperability.
The purpose of the device is to transmit the speech (voice) from a Microphone to a nearby speaker using the binary amplitude shift keying modulation/demodulation.
so when I speak from the microphone I can hear my voice from the speaker, but the way of transmitting the voice should be by Binary Amplitude Shift Keying modulation/ demodulation. so of course I will need an analogue to digital converter at the transmitter to convert the speech waveform from the mic to binary(1 and 0),
So if there is a mic with ADC comes in one part that is fine, i will need a mixer to modulate the binary signal on a carrier signal and then the output from the mixer should go to a bandpass filter and then goes to the demodulator to recover the binary signal and then to lowpass filter and then to DAC (Digital to Analogue converter) so then the voice signal can be heard from the speaker. It should be a small device which can be built on a Vera board and has all the components on the same board from the mic to the speaker (any small speaker).
So I don't want to buy a ready modem, what I want is to construct a simple one that do the job of transmitting the speech from one end to another end (speaker),let's say 15-20 cm away through a hardwire channel, It has the same idea of the intercom but here we should use modulation and demodulation theories, so we can call it modem!
Mail from AM UK
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