The following operators can be used to better focus your queries.
( ) , AND, OR, NOT, W/#
? single char wildcard, not at start
* multi char wildcard, not at start
(Cat? OR feline) AND NOT dog?
Cat? W/5 behavior
(Cat? OR feline) AND traits
Cat AND charact*
This guide provides a more detailed description of the syntax that is supported along with examples.
This search box also supports the look-up of an IP.com Digital Signature (also referred to as Fingerprint); enter the 72-, 48-, or 32-character code to retrieve details of the associated file or submission.
Concept Search - What can I type?
For a concept search, you can enter phrases, sentences, or full paragraphs in English. For example, copy and paste the abstract of a patent application or paragraphs from an article.
Concept search eliminates the need for complex Boolean syntax to inform retrieval. Our Semantic Gist engine uses advanced cognitive semantic analysis to extract the meaning of data. This reduces the chances of missing valuable information, that may result from traditional keyword searching.
Dynamic doppler subchannels is a method to minimize a transmitted signal's loss in a doppler velocity environment when the actual doppler velocity is not known.
English (United States)
This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately
55% of the total text.
Page 1 of 3
Dynamic Doppler Subchannels
Dynamic doppler subchannels is a method to minimize a transmitted signal's
loss in a doppler velocity environment when the actual doppler velocity is not
Doppler energy loss in dB for noncoherent detection is given by:
where Theta(D) is the rate of change of the signal in degrees/second and Delta t
is the integration time.
A typical method to reduce this loss in a doppler velocity environment is to
divide Delta t into several (N) smaller intervals and then noncoherently combine
the energy from these intervals. This does reduce the loss somewhat, but has
the disadvantage of a large mixing loss even with no doppler velocity.
The doppler subchannel method described here also requires splitting Delta t
into intervals until the loss per interval is well within the specified requirements.
The method of recombination is different.
The relative performance of this approach versus an uncompensated
approach is shown in Fig. 1. The uncompensated approach has a large loss as
doppler velocity increases. By adding the plus and minus doppler channels, the
optimum loss is minimized, as shown by the heavy solid line. The actual
performance of this 3-channel approach is slightly less than the theoretical loss
due to the mixing loss involved in selecting the best of the three subchannels.
Relative to Fig. 2 at A1, the "yes" output is taken at the
beginning of each symbol. Subchannel accumulations are zeroed (A2)
and the optimum phase change (phi) pe...