Putnam County SO

[JRayfield]

MOTOTRBO systems are more 'computer network' than they are 'radio systems'. Anyone who works with one needs to have some knowledge of computer networking or problems may (likely) arise. Also, there are parameters that must be programmed properly in the mobiles and portables or the roaming probably won't work correctly either, with results very much like you've described. One way to set up these parameters correctly is to start with computer-generated propagation coverage models, which can be used to get initial values for these parameters. Without somewhere to start, it can be like hunting for a needle in a haystack, as various values are tried and then changed, etc. The initial values from coverage models will at least give a starting point, and from there, the system can be 'fine tuned'.

Shoot me a private message here, with your contact information, and I'll give you a call and go into more detail.

John Rayfield, Jr. CETma

thassler......Thanks for the response. This may be the answer to one of the many issues that we have had with this digital system. I have expressed my concerns to are radio repair personnel that I believed that a roaming problem existed. Each of our repeater sites are named in respect to their geographic location. As you are driving throughout the County, you can watch the towers change on the radio ID screen on the mobiles in vehicle and on the portables. There are times that our guys can be within eye shot of a tower site, but showing a different tower site on their radio outside the geographic area that they are in. This results in garbled transmissions or guys just not getting into the Comm Center at all..

 

[thassler]

..Chief2402.
If your radio techs are using standard internet connections with a router and port mapping to connect your sites you will have problems. You will find that multicast traffic gets intermittently blocked by service providers. We use a product by DCB that is essentially an ethernet bridge. It creates an encrypted tunnel and passes all IP protocols including multicast traffic. All the sites will appear to be on the same network. You will need a master unit at the main site and then a peer unit for each additional site.
We use the model UT-3302 (a google search on ut-3302 will get you there). We also had the same roaming problem you described. Tell your radio techs to set the "RSSI Threshold dBm (The one in the Roam List)" to ~"-98" for portables and ~"-95" for mobiles. You will have to play around with that setting to see what works best for you. Those numbers helped us but I still need to tweak. The default is "-108" and that just seems to make the radios hang onto a weak site to long. The radios will not try to roam until the RSSI Threshold is broken.
Also, if John is offering a phone call I would take him up on it. I've read many of his posts that helped us out when first putting our Trbo system together.... - thanks John

-Trey