Scanning/programming strategy quibble

[Blaise]

Hey all, here's a persnickety question for you.

My primary interest in GMRS has been to set up family communications, both for emergencies and to give my young kids a bunch more freedom without handing them a phone.  However, in line with being prepared for emergencies, I scan a lot of the time so I can make contacts with regular users out there and know where/when they are likely to be monitoring.

However, I have a scanning problem.  I keep my radios programmed with three channel blocks.  The first is the basic 22 simplex channels, the next is the 8 repeater channels, not set for any CTCSS/DCS codes, for use when travelling/discovering new repeaters (So I have a quick way to program new repeaters in from the radio on the go), and the last is my local known repeaters.  When I scan, what I've found is that I invariably first catch new transmissions on one of the simplex channels or on a "blank" repeater channel, rather than on the programmed repeater channel it's actually on. 

So, I removed the blank repeaters from scan to decrease the chances of a wrong channel stop, and have discovered that I *still* almost invariably first catch new transmissions on one of the simplex channels, rather than on the programmed repeater channel it's actually on.  then I tried reversing the direction of the scan (on units capable) or reprogramming the locations of the respective blocks so that the scan hits the repeater channels first, and found that now, I pick up a new transmissions on the programmed repeater channel about 20% of the time, rather than the 1% I was getting before.  Progress, but still not super-effective.

So here's my question.  What the hell is going on here?  With the three block scan, shouldn't I have been picking up on the correct channel approximately 33% of the time?  With only two blocks scanned, shouldn't I be picking up on the correct channel approximately 50% of the time?  With the reversed scan order, shouldn't it be *more than* 50% of the time?

This isn't a major issue, of course, but math seems to be broken, and that makes me angry on a very deep level!

[back4more70]

GMRS repeater outputs share frequencies with simplex channels 15-22.  Is that your predicament?

https://www.buytwowayradios.com/blog/2022/11/list-of-gmrs-frequencies-and-channels.html

[Blaise]

15 minutes ago, back4more70 said:

GMRS repeater outputs share frequencies with simplex channels 15-22.  Is that your predicament?

Yes, they share output frequencies with simplex channels 15-22.  That's the point, but not the question.  When scanning, if your simplex channels have no squelch codes on them, they recieve repeater outputs just fine. 

The "predicament" is that during a scan where three channels might pick up a transmission, you would assume, statistically, that you would pick up on the correct channel approximately a third of the time, not effectively never. Likewise, you would assume that if there were only *two* channels that might pick a transmission, that you would pick up on the correct channel approximately half of the time, not 20% of the time.  This is not good-mathy, and makes my brain ache.

[marcspaz]

So, if I am tracking correctly, you have rChx with TSQL programed in scan and the simplex version Chx with no tone programed in, but it only stops on the simplex frequency?

 

For example.  Repeater Channel 20, tone squelch set to 141.3.  Simplex Channel 20, with no tone.  Everything works as intended in this state.  You hit the scan feature, repeater traffic is present, but the scan feature stops on the simplex channel most of the time?  Even is the scan feature is used to scan from the high memories to the low memories?

[Sshannon]

It’s really going to depend on how the software orders the scan. Do you create scan lists of specific channels?  Do you have multiple scan lists or one big one?  Or is there just on-scan and off-scan for each channel.

If you remove the RX tones for everything, how does it do?

[Blaise]

2 hours ago, marcspaz said:

So, if I am tracking correctly, you have rChx with TSQL programed in scan and the simplex version Chx with no tone programed in, but it only stops on the simplex frequency?

 

For example.  Repeater Channel 20, tone squelch set to 141.3.  Simplex Channel 20, with no tone.  Everything works as intended in this state.  You hit the scan feature, repeater traffic is present, but the scan feature stops on the simplex channel most of the time?  Even is the scan feature is used to scan from the high memories to the low memories?

This is the exact thing.  Like I said, not a major issue, but maddeningly incomprehensible.  Happens on both my HTs and my mobile.  I've started keeping tallies in my head to see if this is just perception bias, but it still seems to work this way!

 

[Blaise]

2 hours ago, Sshannon said:

It’s really going to depend on how the software orders the scan. Do you create scan lists of specific channels?  Do you have multiple scan lists or one big one?  Or is there just on-scan and off-scan for each channel.

Everything I have has only scan on/off per channel, not groups or anything.
 

2 hours ago, Sshannon said:

If you remove the RX tones for everything, how does it do?

I haven't tried that.  Maybe I should set up an experiment...

[WRKC935]

First off what is a 'channel block'  forgive my ignorance.  I have been a commercial radio tech for going on 15 years and a ham for 30.  Never heard that term.  I see things in zones and channels.

If you are scanning the simplex channels with NO tone, and scanning the repeaters with tone the radio can stop on either one if a repeater is transmitting.  If it's not looking for any tone, then any tone will work as well as no tone at all.  Because it's not looking for it.

No clue what radio you are using, so I can't even comment on the idea of priority scan.  If it's a commercial radio, and it has priority scan running it will look at a channel, then the priority list, then the next channel in the scan list then the priority list again, then the next scan list member.  This can slow scanning down a good bit, and commercial radios are NOT good scanners.  They are not fast with standard scanning, and when you turn on priority scanning they get really slow. 

 

My advice, if you are gonna be scanning, buy a scanner.  In fact as long as the stuff you are scanning is analog and not P25 trunking, buy several scanners.  If you do have trunking stuff you are wanting to monitor, get a scanner for that too.  Analog scanners are dirt cheap because they don't listen to the police any more in many places.  But if you are wanting to monitor GMRS, ham or other analog stuff they work great.

 And trying to figure out what a radio in scan mode is doing by looking at percentages of when it stops and opens up isn't really gonna work out for you.

 

 

[marcspaz]

9 hours ago, Blaise said:

This is the exact thing.  Like I said, not a major issue, but maddeningly incomprehensible.  Happens on both my HTs and my mobile.  I've started keeping tallies in my head to see if this is just perception bias, but it still seems to work this way!

 

 

That is very odd. I'm not sure why that is happening.

 

just a WAG based on no real understanding of how the function works, It may have something to do with speed and the additional time needed to process the tones vs the channels with no tone is an instant open, so that channel win?