#Soundwaves bartlett series

It was known that β has some 'canonical' values for waveguides with simple sound speed profiles (SSP). A reasonable prediction of the value of β is often necessary in such applications. It has been found that β may be useful in many applications in underwater acoustics. On the basis of the principle of stationary phase, Chuprov proposed a scalar parameter-the waveguide invariant β, to interpret the dispersive properties of underwater acoustic waveguide.

The resulting range estimators demonstrate better peak-to-sidelobe ratios than a simple incoherent average. An appendix demonstrates how these sidelobe properties can be exploited when combining ambiguity surfaces through use of gradient and Radon transform information. Sidelobe trajectories also exist in the range-depth plane, but they contain no information about the correct source depth. These interference trajectories are demonstrated to exist in simulations, broadband source tows, and a type A blue whale vocalization. As the ambiguity surface of the Bartlett matched-field processor has a physical interpretation in terms of a time-reversed acoustic field, with the sidelobes analogous to local interference maxima, these invariant concepts can be reformulated for application to MFP. This behavior can be explained by the theory of waveguide invariants, which predict the local behavior of interference maxima/minima of acoustic intensity in the frequency-range plane. In isovelocity or bottom-interacting environments the sidelobe trajectories are straight lines that converge to the true range at zero frequency, while environments with upward-refracting sound-speed profiles have trajectories that asymptotically converge as the frequency approaches infinity. This sidelobe shift can be viewed as a continuous trajectory in a range-frequency plane at a fixed depth, where the trajectories converge to the correct source range for a perfectly matched surface. If you need to convert a low-Z condenser mic to high-Z unbalanced using a transformer/adapter, run the mic through a stand-alone phantom supply before converting it to high-Z unbalanced.Ambiguity surface sidelobes generated by the Bartlett matched-field processor (MFP) shift location with frequency. Plug another mic cable between the supply’s output connector and your mixer mic input. The supply has XLR-type input and output connectors, one pair per channel.Ĭonnect a mic cable between your microphone and the supply’s input connector.

#Soundwaves bartlett series

In any case, you plug the supply in series with the mic cable.

An example of a single-channel, stand-alone phantom power supply. Some can power a single microphone others can power several at once.

Some supplies are AC powered some are battery powered some are both. You can buy a phantom power supply ( Figure 5) from your microphone dealer or online. For this reason, it’s best to switch off phantom power for dynamic and ribbon mics. Or if one terminal of the coil or ribbon is accidentally shorted to the grounded mic housing, a current will flow through the coil or ribbon. However, if there’s any imbalance in the phantom voltage applied to pins 2 and 3, a current will flow through the microphone voice coil or ribbon (which is connected to pins 2 and 3). That’s because the voice-coil or ribbon leads are not connected to pin 1, so no current from the phantom supply can flow through them. You can plug a dynamic or ribbon microphone into a phantom supply without damaging the mic. The ribbon leads are soldered to XLR pins 2 and 3 inside the microphone. Sound waves vibrate the ribbon in a magnetic field and generate corresponding electrical signals. In a ribbon microphone ( Figure 4), the diaphragm is a thin metal foil or ribbon. The voice coil leads are soldered to XLR pins 2 and 3 inside the microphone.

When sound waves vibrate the diaphragm and its attached coil, the coil vibrates in the magnetic field and generates an electrical signal similar to the incoming sound wave. This voice coil is suspended in a magnetic field. In a moving-coil dynamic microphone ( Figure 3), a coil of wire is attached to a diaphragm. A dynamic (moving coil) transducer or mic capsule. It generates its own electricity like a loudspeaker in reverse. In contrast, a dynamic microphone needs no power because it has no active electronics. Sometimes other transistors are added to give the mic a balanced output, and these components work off phantom power too. The converter needs a DC voltage to power it, and this voltage is supplied by the phantom power supply. This circuit is necessary whether the capsule is electret or non-electret. To bring that impedance down to a usable value, an impedance-converter circuit is connected to the capsule output. The output of the condenser mic capsule is extremely high impedance so it is very hum-sensitive.