Reciever Isolation

[John Metcalf]

Luke pointed me to a website and

[John Metcalf]

and I didn't get to finish my thought. It has to configuring the system to favor the receiver sensitivity when possible, but still isolate it enough from all transmitters. We can do this by placing as few as possible filter cavities in front of the receiver. I'm trying to do the isolation analysis to figure this out.

http://www.repeater-builder.com/antenna/ant-sys-sys-engr.html

Rule number 1: Always favor your system receiver. A system's coverage area is primarily determined by how well it receives stations in the field, not by how much transmitter power it has.

Rule number 2: This goes hand in hand with Rule number 1: Maximize your received signal. Maximize the isolation from receiver to transmitter. Concentrate on minimizing the insertion loss on the receive side of the system. Test for Effective Sensitivity frequently (at least twice a year) - this includes tests with the transmitter on (but keep in mind the effective sensitivity can be a dynamic value unless the environment is a broadcast site with a constant RF environment). Keep good records - a site logbook is important. If something changes between visits you need to find out what changed and why.

[John Metcalf]

Here is another:

http://www.repeater-builder.com/antenna/thoughts-on-isolation.html

Repeater performance is defined by RF performance as well as audio performance.   You can have the best sounding repeater on the planet, but if the users can't get into it or hear it then it's worthless.   Audio performance is covered elsewhere on this web site.   Good RF perfomance is a balance between receiver and transmitter... you want neither an "elephant system" (all ears and no mouth) or an "alligator system" (all mouth and no ears).   It gets complicated when some users use flea-powered handhelds, some use 10w mobiles, some use 50w mobiles, and others use hilltop remote bases.   What set of users do you use as a reference for "balanced"?   You have to consider the demographics of your users.

And with respect to doing the isolation requirements analysis there is a sheet here to help determine what is needed: http://www.repeater-builder.com/tx-rx/tx-rx-tech-aids.pdf

Thanks to Luke for finding this info.