Perhaps you should try some spelling variations:
"telecommunication systems passive." » "communication systems passive.", "telecommunication services passive.", "telecommunication sectors passive.", "telecommunication servicess passive.", "telecommunication unions passive.", "telecommunication system passive.", "telecommunication systems practice.", "telecommunication systems adaptive."
"telecommunication system active." » "telecommunication sector active.", "telecommunication services active.", "telecommunication union active.", "telecommunication system achieve.", "telecommunication system activity.", "telecommunication system passive."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("telecommunication systems passive.") or ("telecommunication system active."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("telecommunication systems passive.") OR ("telecommunication system active."))*.
• Removing quotes may allow a broader search: (( telecommunication systems passive. ) or ( telecommunication system active. ))*.