понедельник, 9 августа 2010 г.

An interesting signal from UDXF conference discussion.


The very interesting signal, which record has been represented by Mike, appeared in UDXF conference.
The record itself, is ~2 minute I/Q file, with capacity 16 bits, the size of the file is nearby 80-90 mbyte.
Actually, there are many various signals in this record, we have marked some on the general spectrogram.

General view.


Presence of two chirps seemed very interesting to us. That has allowed to measure key parametres and to find out some curious nuances.


There is an interesting gaps(breaks), in the same positions, on two independent chirps.

In generall, the basic interest, certainly represents, not absolutely clear/understandable system, which is well visible on this spectrogram and designated on the general sonogram by green colour.

Unfortunately, on this record, it is impossible to tell precisely what width of a spectrum has this signal. Presumably it can be about 20 kHz. Nevertheless, it is well visible, that the signal has FHSS signs. It is also rather not difficult to receive key/basic parameters. It is well visible that the nature of impulses, practically in all bursts, is absolutely identical. That is strange enough, if the system is intended for real information transfer.

We are still have difficulty to classify this signal. Firstly, there is not enough data - the only one record. In the second, we didn't have similar records before. Besides, the subject of interest has too blurred limits(boundaries) and relatively weak level, plus it is liable to considerable selective fadings.

At the conference, also the other signal is discussed. The parameters of this signal, differ from the first signal, but both these signals have similar impulse nature, and close structure (an alternation of the small identical bursts). Probably, there are a lot of such signals in the air, all these signals can be different, but they are very interesting signals observe to.