My new Office has an old system looks like bnc connectors. What's the best way to update this? I can't rewire it as its goes through walls and ceilings so stuck with the coax cable. Advice please. Can I go full or HD? The problem I have is I can't see people's faces so new cameras might be needed. I think the system is about 8 years old.  The hard drive recorder + screen is also noisy and outdated. 
  
What system would you recommend?  At the moment the 9 cameras are fixed in housing and Im happy to keep these without going for PTZ. 
  
thanks 
  
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