Nah, it's a 1939 espionage cipher for transmitting Chinese characters. 147MB for a 97 page scanned .pdf is a bit extreme so piping it through Acrobat, selecting Optimization and OCR shrinks it to 20MB. Checking OCR results using SPELLING script on page 20 copied to an LibreOffice text page yields:
盟伊盤:L皿LIN
(there are four kanji in the above line if you don't have the font)
The first three translate to : leader Italy tray then a smiley with its tongue hanging out then a character meaning dish, or a helping then LIN (wherever that is). :-)
