Knowing that the BCD436HP trunked system data comes from the Radio Reference database and that RR identifies the control channels... Does the scanner scan all the Frequencies/Channels for a site? Is it necessary to have all the Frequencies/Channels for a site loaded and scanned? I am wondering if I can speed up scanning of multiple sites and trunked systems if I do not load or Avoid the non-control frequencies.
Thank you for your responses.
Removing the "extra" frequencies will not materially affect your scan speed. For the Uniden scanners, the radio will use the first frequency where it can receive & decode the control channel information. Once an active transmission is completed, on the site where that frequency was used, the scanner will move on to the next site, not check other frequencies in that specific site. Those members who had the older 396T series scanners, had to create a separate system for each trunked system site. The "T" series did not have multi site capability. That arrived with later Uniden models. (The 996T, released later than the 396T, did have multi-site ability, as have all subsequent trunking scanners.)
The GRE/Whistler scanners such as the PSR500 & it's siblings, including the Whistler models WS1040 & WS1065, can be programmed to check
all of the frequencies in a site for activity. However, that is not an option for Uniden models. For those specific Whistler models, with a limited memory capacity, using control channel frequencies only helps free up space for other items.
For the Uniden database scanners, like the x36HP & SDS series, whether you have all of the site frequencies, or only the control channels does, not really matter. The much larger memory capacity for Favorites lists, in most cases, removes the need to economize your entries. If you were scanning using your location, range, & the main database,
all of the systems in the Sentinel database have all of the frequencies as shown on the system's database page in the RR database you see online. Sentinels database does not contain anything that 'flags' control channels.
However, for the SDS series scanners, the scan speed is definitely impacted by multiple sites on the same system. It takes up to about a half second for the scanner to acquire & decode the control channel data. So, in a large regional or statewide system, if you have multiple sites programmed, it's going to at least attempt to check each for activity. Removing (or avoiding) the out of range sites, or those that do not carry the radio traffic you are interested in, will speed up your scanning.
That note, on the SDS series scanners, was from the late Paul Opitz, "UPMan", during posts shortly after these scanners were introduced. I don't recall a similar, specific, note for the x36HP or other DMA scanners, but I suspect that there might be a scan time penalty, though possibly small, for the other models.
Just note, though, that for L3-Harris P25 systems,
any of the frequencies for a given site can be used as a control channel. These systems tend to rotate the frequency used for control among the ones assigned for that site.
