What is meant by acoustic coupling?
: a device that converts digital signals to audio signals in order to allow the transmission of data (as from a computer) over a telephone line An acoustic coupler …, tightly strapped to the phone receiver, allows the computer to fire audio tones directly through the handset, the way we do when we speak.—
How does an acoustic modem work?
An acoustic modem is used to transmit data underwater, much as telephone modems are used to transmit data over phone lines. An acoustic modem converts digital data into special underwater sound signals. These signals are then received by a second acoustic modem and converted back into digital data.
Who invented the acoustic coupler?
Robert WeitbrechtAcoustic coupler / InventorRobert Haig Weitbrecht was an engineer at SRI International and later the spin-off company Weitbrecht Communications who invented a type of a modem. Wikipedia
Does RF work underwater?
Electromagnetic (EM) waves, in the RF range, can also be a good option for underwater wireless communication systems. EM waves are less sensitive to reflection and refraction effects in shallow water than acoustic waves. In addition, suspended particles have very little effect on them.
What is a hydrophone used for?
A hydrophone is an underwater device that detects and records ocean sounds from all directions. People often think that the underwater world is silent. In fact, numerous marine organisms use sound for communication, reproduction, and to seek prey.
Why is impedance matching needed?
Why is impedance matching needed? Impedance mismatch can lead to signal reflection and inefficient power transfer. These reflections cause destructive interference, leading to peaks and valleys in the voltage. Impedance matching is therefore important to obtain a desirable VSWR (voltage standing wave ratio).
What is the history of the first acoustic modem?
An early commercial model was built by Livermore Data Systems in 1968. One would dial the computer system (which would have telephone company datasets) on one’s phone, and when the connection was established, place the handset into the acoustic modem.
When did the first 1200 baud modem come out?
The practical upper limit for acoustic-coupled modems was 1200 baud, first made available in 1973 by Vadic and 1977 by AT. 1200 baud endpoints became widespread in 1985 with the advent of the Hayes Smartmodem 1200A, though it used an RJ11 jack and was not an acoustic coupler.
What is an acoustic coupler?
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone .
What is the Weitbrecht Modem?
His acoustic coupler is known as the Weitbrecht Modem. The Weitbrecht Modem inspired other engineers to develop other modems to work with 8-bit ASCII terminals at a faster rate. Such modems or couplers were developed around 1966 by John van Geen at the Stanford Research Institute (now SRI International ), that mimicked handset operations.