I think I posted about this before, but I don't remember getting any good explanation.
When I am using a newer Trimble receiver that has a webUI (Alloy, R10, R12, R750, etc) I usually go into the WebUI and enable all of the tracking options, and then start a survey, either static or as an RTK base.
For example, here is an Alloy (does not have QZSS enabled) in the first image below
If I am doing RTK over cell (usual method), the amount of data added to the stream is not significant. However, if doing RTK over UHF, then it does make a difference. If I am doing RTK over UHF I will often just use GPS and Galileo, that seems to be able to fit in the bandwidth every 1s.
But, if I start a survey using a data collector, it turns off some of these signals...as seen in the second image.
Note that I have SBAS turned off because otherwise it seems to use SBAS and not RTX, and by using RTX I can get a very accurate base position in about a minute.
I would like to hear a good explanation from Trimble (or others who have knowledge) why they always turn off some of the signals. Maybe they don't add anything to the solution? But it seems to me the more the better, especially since storage memory is plentiful and at least over cellular the bandwidth is not an issue either. Certainly over UHF it is an issue.
Assuming you are using Access, check out the "GNSS Signal Tracking" in "Base options" for your survey style...
Also when using your UHF radio consider bumping the mask up to 15° to cutout some of the low sats that are probably struggling to get though a tree or building anyway.
With Leica GS18 using the 1w internal satel radios (8FSK, Leica 4G message, 25khz as not narrow band here) most satellites I've ever had is 44 used (not just tracked), all constellations on and good latency. With Geomax gear (same radio but RTCM3.2MSM which isn't as compact) more like high 30's but still ok if no interference.
Understand Trimble's CMRx is pretty compressed too so surprised you are needing to drop constellations, that sounds more like radio cable or interference problem. Time for a new tool? https://m.youtube.com/watch?v=IV4Q8ePSpb4
