So now there 4 sites in the mix. I have been listening only to the Monroe site for a couple of years and was assuming I was hearing everything.
When monitoring a site, you will hear all talkgroups being used by that site. You will NOT hear talkgroups NOT being used by the site.
I am hearing OPFD and OPSO only on the new site.
As expected. What that means is no one using MPD talkgroups are connected to the new site. Sites only broadcast if there's someone to listen (an actual affiliated radio, not us scanners).
Will I hear it on Monroe till he picks up the Cypress site and only him and dispatch?
No. You will hear all units on that talkgroup as long as one unit has a radio connected to the site you are monitoring.
Are the east side OPFD stations going to be on the Monroe site while the southwest area traffic is going to end up on the new site
No. The Cypress OPFD station is close enough to the site (obviously, its down the street) that it's base radio will always be connected to the new site regardless of where the units are. Likewise there will always be a unit on OPFD Dispatch 1 talkgroup connected to the Monroe site. You will hear all traffic on both sites (and Calhoun & West Monroe also).
I still hear all the troopers on the Monroe site and never on the Cypress.
I experience the same when monitoring it. It's because no one tuned to LSP Troop F Dispatch 1 is connected to the new site (at the time).
I guess I am just really puzzled how the system figures out which sites to transmit on when they aren’t using simulcast.
I was in the same boat. Think about the sites and their limited number of frequencies. It's impossible to transmit every talkgroup in use on the whole system ON EVERY SITE. For the radio user (a unit with an actual affiliated radio), they don't notice a thing. They key up, and someones there. Regardless. For us "receive only" guys and gals it takes some understanding of the system to be able to monitor what we want to monitor.
Think of it like a computer system. Because it basically is. I run an SDR app and can see radios logging in, logging out, changing channels, etc that you never "hear". I monitor Bastrop 3-12 which is fairly busy. A Balentine EMS unit with a radio on their primary dispatch comes within range to connect to the site. As long as it is connected, I can hear all traffic from all radios on that talkgroup regardless of where they are located. At some point, traffic will cut out. That means that unit left the coverage area.
A geographical example of something you're familiar with: Since OPFD Swartz station and Fairbanks station are close enough north to have base radios on the Bastrop site, I can monitor OPFD Dispatch 1 and everyone else on it pretty much 24/7. OPSO units are almost always north enough to do the same, therefore I can almost (less than OPFD but still a lot) monitor OPSO Dispatch 1 and everyone on it. MFD/WMFD units are almost NEVER north enough to connect to my site and therefore I almost NEVER pick up those talkgroups. Even though I hear Natchitoches SO because one of their units came to Bastrop (mental health centers).
Lastly I guess I will need to scan both sites now.
To monitor certain desired talkgroups, yes you will have to scan more sites. If Ouachita was simulcast, you could hear everything as all 4 towers would function as "one site".
We can only hope.