Diamag

DESCRIPTION

This device makes it possible to authenticate a recording, to detect if a recording was edited, to identify erased spaces on magnetic tapes or recover partially erased information. It also allows identifying a recorder and indicating a recorder’s faults, as well as carrying out analysis of images of magnetic field distribution on the surface of the magnetic recording media.

Operation of DIAMAG is based on magnetic field distribution visualization based on the magneto-optic effect. It may be described as follows: A magnetic tape to be checked is placed to the cassette receiver where it contacts with a magneto-optical plate (titanium-sapphire), which is built into a polarizing microscope.

Magnetic field of the tape acts on the magneto-optical plate and forms an area with distributed optical properties in it. At various positions of the area, polarization of the light turns through various angles depending on the field strength distribution in the tape. Observing the polarized light passed through the magneto-optical plate with a special microscope it is possible to get an image that visually describes the magnetic domain structure on the magnetic tape surface.

The device is fitted with a tape-drive mechanism providing the tape transport in both directions with adjustable speed as well as intermittent movement of the tape. A special adaptor is used for microcassette tapes.

The DIAMAG system operates in four modes: display mode, recording mode, saved images processing, and automatic defect search.

In the display mode the user can view the structure of a moving magnetic tape with the resolution of at least 10 µm in the monitor screen. The tape moves at a relatively slow speed so that the user can discover defects of the recording visually. A defect having been discovered, the user can stop the tape, examine the tape area around the defect and then continue the examination or record and store the image.

While in the display mode the user can save all viewed frames to the hard drive. The recording mode allows recording and saving images with high resolution (around 1 µm) to the hard drive.

In the Saved images processing mode, you can enhance the image quality adjusting the optical system parameters that help in image analysis. Analyzing images stored on an HDD you can calculate the image geometry (i.e. left and right channels width and distance between the channels), compare images, and automatically fill in the form of the image analysis report. You can also easily produce datasets of images and analysis information, delete images you don’t need, and save information to an archive.

In case the tape was completely recorded and stored on an HDD as an image sequence, you can go back to any specific part of the recording.

Automatic search of defects makes your work much easier especially in case numerous cassettes need to be analyzed. In this mode, the software analyses all the images from a specified set checking each image parameters such as the position of magnetic head channels trace, shift and width of the channels, signal drop or absence, and some other. During the procedure, the software shows both the image and the corresponding information obtained with the use of specific algorithms on the monitor screen. In case the automatic search is in the Recording mode, the software may stop the tape transportation when a defect is detected until you decide to continue the analysis or, if there is no user’s reaction, continue the automatic analysis after some time. You can choose to store the image with a detected defect on an HDD as a high resolution image or simply to mark the corresponding image in the low-res image sequence. The low-res sequence is stored separately from the high-res images, which makes it possible to repeat the automatic analysis with different defect search parameters or fulfill visual analysis without additional read passes.

Along with the magneto-optical analyzer, the DIAMAG system includes an IKAR-Lab system for forensic analysis of audio recordings. The system was developed in the Speech Technology Center, St. Petersburg, Russia and allows identifying a person by their speech recording, verify analogue and digital recordings, carry out noise analysis, as well as diagnose the acoustic environment and recording conditions and enhance the recording quality and speech illegibility.