Introduction to Signal Processing, by Tom O'Haver.  
January 2019 version.
http://terpconnect.umd.edu/~toh/spectrum/IntroToSignalProcessing2019.pdf
Language: American English
Style: Academic/Scientific
Intended audience: College students, gradulate students, researchers

Readability analysis conducted by
http://www.online-utility.org/english/readability_test_and_improve.jsp


Number of characters (without spaces):	937,793.00
Number of words:	186,904.00
Number of sentences:	13,906.00
Average number of characters per word:	5.02
Average number of syllables per word:	1.67
Average number of words per sentence:	13.44


Indication of the number of years of formal education that a person requires in order to easily understand the text on the first reading
Gunning Fog index :	11.3

Approximate representation of the U.S. grade level needed to comprehend the text :	 
Coleman Liau index :	11.52

Flesch Kincaid Grade level :	9.9	
ARI (Automated Readability Index) :	8.82	
SMOG :	11.41	
Flesch Reading Ease :	54.70

	
ATOS Level............................11.8 
Average vocabulary level...............5.7
ATOL level determined by
http://www1.renaissance.com/Products/Accelerated-Reader/ATOS/