Sensors are all around us collecting data on weather, climate, traffic, air, and water quality, and a host of other parameters too numerous to list. Some of this data is very rich and the collection and transmission are continuous thereby taxing communications networks. Transmission is also power-intensive and can be the most difficult aspect of the power budget of remote sensors. Thus, minimizing transmission time saves sensor battery, providing a longer operational life. A shorter transmission time also avoids needlessly occupying the communications link when the link is bandwidth limited.
Further complicating remote sensor data transmission, many applications send the raw time series data or spectrogram over the link. This is often wasteful since there is extraneous information in the raw data, but the signal processing required to pull salient information may be too computationally intensive for a power-conscious remote sensor.
Of course, data compression techniques have been employed to shrink data, but without any knowledge of the signals of interest, they invariably result in suboptimal compression or cause the loss of important information. Further, the user receiving the data may be unaware that any data is missing.
Addressing the above, Navy scientists have developed a data compression and transmission method that includes receiving sensor data which is digitized and transformed into a spectrogram. The spectrogram is filtered and converted into a binary representation and a Hough transform is used to find lines in the representation. Related lines are combined and then converted back into time-frequency space. Lines are optimized and composed into a binary message, transmitted and received at a remote location where a reconstructed spectrogram can be created from the lines. Transmission can be electrical, optical or acoustic over a wire, fiber optic cable, or radio transmission. Accompanying the transmission are parameters such as power, stability, width, and wander.
Compression by approximating the spectrogram as a collection of lines is a reasonable assumption when the signals of interest contained in the spectrogram are continuous wave (CW) tones or linear frequency modulated (LFM) signals. Each line is assumed to last for the duration of the spectrogram window. By breaking a spectrogram into windows representing a short enough duration for the specific application, an arbitrarily complicated frequency modulated signal can be compressed. Overlapping windows can also be used if necessary to obtain important signal characteristics.
- Designed to minimizes transmission times for remote sensors
- Delivers very large compression ratios by leveraging general information about the signals of interest
- By capturing the lines in the spectrogram, which correspond to the desired signals, there is a smaller chance of losing important data
- Businesses can acquire the technology by licensing US patent 10,060,961 from the Navy
- Potential for collaboration with Navy researchers
- License fees are negotiable, contact TechLink for more information