Interesting scan behavior

AA3RP
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Joined: Thu Jun 17, 2021 3:22 am

Interesting scan behavior

Post by AA3RP » Thu Mar 31, 2022 8:41 pm

I am running the Alpha version on MD9600 hardware versions 4.1 and 5.0 currently. I have noticed on both the following behavior while in scan mode.

When scan stops on a memory channel I have in the zone I am scanning on it will move to the following channel in the zone list and sit there until the pause time ends. I first noticed this when I was not at the radio and wanted to respond on a channel the scan stopped on. By the time I get to the radio and put my call / response out I get nothing back. Then I start scan back up and hit the calling station but on a different zone channel then the one I was calling on.

At first I thought it was the calling station moving around the repeater list, but over time I noticed this happening on the MD9600 and not my other VHF/UHF radio in the shack. So I started watching this more and more. This happens in the current as well as the previous Alpha release. The interesting thing is that it does not happen every time. It does tend to be more often on a 'long' carrier tail or 'long' winded chat, but I have seen it happen also quickly. Not sure what is going on, but the net effect is if I want to get in on the channel the scan caught, I sometimes end up Tx on a different channel, always the following channel in the Zone I am in.

My Scan settings are as follow:
Scan mode: Pause
Scan dwell: 30ms
Scan hold: 30s

I am not sure how to repeat this, but I can watch and see this when I scan my local repeaters especially during the morning and afternoon commute times when there is generally traffic on many of the repeaters.

VK3KYY
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Location: Melbourne, Australia

Re: Interesting scan behavior

Post by VK3KYY » Thu Mar 31, 2022 8:47 pm

Does this only happen the latest Alpha or was the same problem on the previous Alpha?

G4EML
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Re: Interesting scan behavior

Post by G4EML » Thu Mar 31, 2022 9:11 pm

With those settings the scan will continue 30 seconds after it initially pauses. If the call you receive is a long one, say 25 seconds, then you will only have the remaining 5 seconds to respond before the radio starts to scan again.

If you change the scan mode to 'Hold' then the scan will hold until the call ends and you will then have 30 seconds to respond before it starts to scan again. It sound like this might be the better mode for you.

As for sometimes moving onto the next channel. If your squelch is lightly set or there is some local noise it may move on to the next channel and see a blip of noise which will cause it to hold for another 30 seconds.

Colin G4EML

AA3RP
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Re: Interesting scan behavior

Post by AA3RP » Fri Apr 01, 2022 12:02 am

VK3KYY wrote:
Thu Mar 31, 2022 8:47 pm
Does this only happen the latest Alpha or was the same problem on the previous Alpha?
It happens in current AND previous Alpha versions

To be more concise, when the carrier drops on the channel the scan has locked onto it will move to the next channel in the list and sit there until the pause timeout completes.

As stated previous this is not every time but does happen frequently enough that I can see and catch it during times of busy repeater use. I have not figured out away to repeat this behavior every time.

VK3KYY
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Location: Melbourne, Australia

Re: Interesting scan behavior

Post by VK3KYY » Fri Apr 01, 2022 12:19 am

AA3RP wrote:
Fri Apr 01, 2022 12:02 am
VK3KYY wrote:
Thu Mar 31, 2022 8:47 pm
Does this only happen the latest Alpha or was the same problem on the previous Alpha?
It happens in current AND previous Alpha versions

To be more concise, when the carrier drops on the channel the scan has locked onto it will move to the next channel in the list and sit there until the pause timeout completes.

As stated previous this is not every time but does happen frequently enough that I can see and catch it during times of busy repeater use. I have not figured out away to repeat this behavior every time.
OK.

There have been changes to the timing of everything, which potentially may have caused this.

However if it was happening in the version from 1 or 2 weeks ago, then its nothing to do with the timing

Do you have a GD77 (or DM1801 or RD5R) and if so did you experience the same problem ?

VK3KYY
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Location: Melbourne, Australia

Re: Interesting scan behavior

Post by VK3KYY » Fri Apr 01, 2022 12:25 am

BTW

Is this a FM or DMR signal ?

What mode is the channel set to?

Do you have CC Scan enabled or TS filter disabled ?

Or is the repeater multimode?

AA3RP
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Re: Interesting scan behavior

Post by AA3RP » Fri Apr 01, 2022 1:05 am

VK3KYY wrote:
Fri Apr 01, 2022 12:25 am
BTW

Is this a FM or DMR signal ?

What mode is the channel set to?

Do you have CC Scan enabled or TS filter disabled ?

Or is the repeater multimode?
I have had and seen this in both FM and DMR,

I am not sure I understand what you mean by what mode is the channel set to? I have both FM and DMR in my 'local' zone that I have scan running while I am about the house and can hear the radio in my 'shack' room. This is where I have experienced this the most often, but I also noticed it on my recent trip where I set up a Zone with repeaters along the travel route and most of the driving time was scanning. At least twice when I went to respond I was on the wrong channel and once I figured this had happened and back up a channel manually and sure enough found the contact and made and had a good QSO.

On the point of the repeater being multi mode, I would have to start keeping a list and checking that. It will take a good day or two to get enough data points to give a valid report back. I will work on that.

I do have a pair of GD77, a pair of DM-1801, and a RD-5R. I have not noticed it on any of them but I rarely scan much on my HT's. I would have to set up a test of them by hooking them up to my external / base antenna and running the scan as the HT's just do not pick up the local repeaters like my base station antenna does. I will do this, but I am quite busy these next few days so it maybe early next week before I get it set up and tested.

AA3RP
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Re: Interesting scan behavior

Post by AA3RP » Fri Apr 01, 2022 1:14 am

G4EML wrote:
Thu Mar 31, 2022 9:11 pm
With those settings the scan will continue 30 seconds after it initially pauses. If the call you receive is a long one, say 25 seconds, then you will only have the remaining 5 seconds to respond before the radio starts to scan again.

If you change the scan mode to 'Hold' then the scan will hold until the call ends and you will then have 30 seconds to respond before it starts to scan again. It sound like this might be the better mode for you.

As for sometimes moving onto the next channel. If your squelch is lightly set or there is some local noise it may move on to the next channel and see a blip of noise which will cause it to hold for another 30 seconds.

Colin G4EML
I have seen this ONLY when I have Pause set for the Scan mode. I did have it set to Hold but I opted to use pause as there are some repeaters I scan that 'regulars' use for ragchew and it can hold the scan for a very long time. I chose Pause so after 30 seconds it moves on regardless if there is carrier / audio or not.

My squelch levels are 45 for both FM and DMR, fairly high.

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F1RMB
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Location: Grenoble, France

Re: Interesting scan behavior

Post by F1RMB » Fri Apr 01, 2022 1:31 am

Hi,

which key are you using to stop the scan, PTT ?

I just tried with the same conditions, and it worls. As soon as I press the PTT key, the scan stops on the current channel.
As Colin mentioned, you have a 30s window to stop the scan to be able to stay on the current channel, as you selected "Pause" scan mode.


Cheers.
---
Daniel

VK3KYY
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Location: Melbourne, Australia

Re: Interesting scan behavior

Post by VK3KYY » Fri Apr 01, 2022 2:34 am

I think I may have observed this for a multimode repeater, but its difficult to know for sure, becuase if so its a very intermittent problem

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