BCT15X: Close Call Questions

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KJ4TDM

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I was wondering if there is a way to adjust the sensitivity for the close call feature? Why do I ask that? Well I have been running my BCT15X mobile w/ a remote head for about a year. I run my scanner in normal scanning mode with either CC PRI or CC DND on. It puzzles me they way it works sometime. Examples: Cullman, AL Walmart, and Walmart distribution, I can be a mile away and my close call will alert me to traffic. Driving around Birmingham, AL it is constantly going off cause of all the signals in that city, note that they are 95% digital so I just lock them out. I drive close, within a mile or so of a tower and it will alert me if there is anything. BUT when I am setting in construction traffic and 4 to 5 cars away from a guy i see talking on a HT doing traffic control, nothing! I have changed the mode to just close call mode and watch the bars move up and down, still no alerts to tell what frequency there on. The local county transportation buses run DMR w/ LRRP, they are constantly transmitting, I have worked on those radios and they put out 50w of power. I can be parked by one or pass one on the road, no hits! So is there anyone that can explain this? Is it a transmit power issue on the other end? If so I know Walmart uses little HT radios programmed the MURS frequencys, they cant be transmitting much power, they don't have a repeater.
 

UPMan

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Short answer: No.

Close Call works by determining the xmit frequency of the strongest in-band transmission, but that transmission must be about 18dB stronger than all other signals in order to be detected as a discrete coherent signal source.
 

KJ4TDM

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Close Call works by determining the xmit frequency of the strongest in-band transmission, but that transmission must be about 18dB stronger than all other signals in order to be detected as a discrete coherent signal source.

Thanks! Thats more info i didnt know. But i do with there was a way to adjust that.
 

KJ4TDM

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the bands can be turned on or off. you might check that first.

I do have some turned off. What i think i have found by doing that is it just cuts down on the time it takes for it to make its way back to that band to scan it again.
 

wtp

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off is off

if you have them off then you get nothing from them.
if they are ones that you want nothing from then yes it "gets" to the other bands quicker.
 

KJ4TDM

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if you have them off then you get nothing from them.
if they are ones that you want nothing from then yes it "gets" to the other bands quicker.

Yes your right, i know that.
 

KJ4TDM

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Your scanner cannot listen to DMR anyway./QUOTE]

It can to listen to DMR, it can hear anything, it just cant decode it.;) But that's not the point, the point is it should alert me to any nearby strong signals.
 

UPMan

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For DMR, Close Call does not work. If you look at the signal, it is only there 50% of the time (one slot) from the bus radio. The data bursts are too small to be detected as a coherent signal.
 

Voyager

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For DMR, Close Call does not work. If you look at the signal, it is only there 50% of the time (one slot) from the bus radio. The data bursts are too small to be detected as a coherent signal.

That's true for simplex and repeater inputs. DMR repeater outputs (including trunked) transmit on both slots and will trigger CC hits.

It's soooo rare that I can correct UPMan. :D (And yes, I know he specified the bus radio which is likely simplex or on an input, but I'll still count it - lol)
 

UPMan

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I'm going to credit that as a clarification...I was speaking to his situation which was on the input side.
 

MStep

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For those who would like to "cut down the sensitivity" of their radio for close-call monitoring, while you can't actually do that on the radio itself, the simple answer is just to use a small, less efficient antenna. One one of my radios with close-call, I simply swap antennas at night so that I will just pick up traffic that is extremely local to me. Of course, that won't work for you if you are also trying to monitor distant traffic at the same time, but my small antenna (I think the one I use if the "Miracle Baby) is great when I am in at home at night, or in malls or other areas and I just want to pick up extremely local activity.
 

wtp

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less is more

rs 800Mhz = miles
rs 800 on input = 1 mile
1.5 inch on input = in the neighborhood
antenna out = they are at my house

with a bcd396T
my rules of thumb
 
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