Domain transform compaction and recovery
View Patent ↗Disclosed are exemplary apparatus, techniques, algorithms and methods for reducing the size of time domain data with minimal distortion. In general, the exemplary techniques use a digital channelizer to convert a time series in to a set of frequency bins. Frequency bins that have a power less than a predefined threshold are converted to zero. The frequency domain data is then compressed using a compression routine. The compressed frequency domain data may be stored or transmitted. Recovery of the time domain data involves reversing the compaction process. Since the digital channelizer produces perfect reconstruction of the time signals, little distortion of the time domain signals occurs.
1. Apparatus comprising:
storage apparatus for storing time domain data;
a digital channelizer processor for processing uniform time-sampled data derived from the storage apparatus, the digital channelizer processor transforms uniform time-sampled data into frequency bins of a plurality of frequency channels, retrieves a predetermined number of values from a data set of frequency bins comprising each frequency channel, determines an absolute magnitude of each frequency channel, determines a lower bound of the absolute magnitude of all of the frequency channels, replaces values in a frequency channel with zeroes if a power level in a frequency bin of the frequency channel is below a predefined threshold, and processes the data set of all channel values using a lossless compression algorithm to reduce the size of the time domain data.
2. The apparatus recited in claim 1 wherein the digital channelizer processor determines the lower bound of the absolute magnitude of the frequency channels using preset values derived from the set of absolute magnitudes.
3. The apparatus recited in claim 1 wherein the digital channelizer processor determines the lower bound of the absolute magnitude of all frequency channels using preset values derived from external information.
4. The apparatus recited in claim 1 further comprising apparatus for storing the compressed data.
5. The apparatus recited in claim 1 further comprising apparatus for transmitting the compressed data.
6. The apparatus recited in claim 1 further comprising:
a second digital channelizer processor for receiving compacted data, uncompressing the compacted data, and inverse transforming the uncompressed data to recover the time domain data.
7. A method comprising:
transforming by a digital channelizer processor uniform time sampled data derived from a storage apparatus into frequency channels;
retrieving by the digital channelizer processor a predetermined number of values from a data set comprising each frequency channel;
determining an absolute magnitude of each frequency channel;
determining a lower bound of the absolute magnitude of all frequency channels;
if a power level in a frequency channel is below a predefined threshold, replacing all of the values in the frequency channel with zeroes;
processing the data set of all channel values by the digital channelizer processor using a lossless compression algorithm to compact the time domain data.
8. The method recited in claim 7 wherein determining the lower bound of the absolute magnitude of all channels uses preset values derived from a set of all absolute magnitudes.
9. The method recited in claim 7 wherein determining the lower bound of the absolute magnitude of all channels uses preset values derived from external information.
10. The method recited in claim 7 further comprising storing the compacted data.
11. The method recited in claim 7 further comprising transmitting the compacted data.
12. The method recited in claim 7 , wherein the digital channelizer processor is a first digital channelizer processor, further comprising:
receiving or retrieving compacted data by a second digital channelizer processor;
uncompressing the compacted data; and
inverse transforming the uncompressed data to recover the time domain data.