# COS Detected can't find cause **URL:** \ **Category:** AllStarLink\ **Tags:** asl3\ **Created:** [November 5, 2024, 5:02pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201 "2024-11-05T17:02:10Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![KC2NJV](https://community.allstarlink.org/user_avatar/community.allstarlink.org/kc2njv/32/3634_2.png) [@KC2NJV](https://community.allstarlink.org/u/KC2NJV)\ **Post date:** [November 5, 2024, 5:02pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/1 "2024-11-05T17:02:10Z")
In the last two weeks or so, out of the blue, my public node will show COS Detected, which produces a tone. I have one public node and 5 private nodes, with each private node connecting to the public. I thought maybe it was SkyWarnPlus’ tail, so I disabled SkyWarnPlus. Not the issue. When I noticed the issue, I started to disconnect private node by private node. I was down to nothing connected in the public node, but the COS continued. I have disconnected my HotSpotRadio USB Hub and changed the public node to (as of 11/5, 07:00 ET) esentially a simple hub: ; duplex = 1 ; turned off hat duplex = 0 hangtime = 400 ;rxchannel = SimpleUSB/62499 ; turned off hat rxchannel = dahdi/pseudo I’ve indepently reached out to HotSpotRadio for their take, because I don’t know if its the hat. It’s only been about 5 hours since I “disconnected” the hat, and possibly too ealry to tell if that fixed the issue. Anyone seen this issue? ---
**Author:** ![N5LSN](https://community.allstarlink.org/user_avatar/community.allstarlink.org/n5lsn/32/2454_2.png) [@N5LSN](https://community.allstarlink.org/u/N5LSN)\ **Post date:** [November 5, 2024, 6:09pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/2 "2024-11-05T18:09:26Z")
FYI, SkywarnPlus just does telemetry and audio playback internally in app\_rpt - it is not possible for SkywarnPlus to trigger a physical logic input such as COS. ---
**Author:** ![N8EI](https://community.allstarlink.org/user_avatar/community.allstarlink.org/n8ei/32/4254_2.png) [@N8EI](https://community.allstarlink.org/u/N8EI)\ **Post date:** [November 5, 2024, 8:26pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/3 "2024-11-05T20:26:10Z")
> [@KC2NJV](#): > > my public node will show COS Detected What are your frequency and CTCSS/DCS settings for the node? And I assume you are not just using squelch and omitting CTCSS/DCS. You could simply be “conflicting” with something else. ---
**Author:** ![KC2NJV](https://community.allstarlink.org/user_avatar/community.allstarlink.org/kc2njv/32/3634_2.png) [@KC2NJV](https://community.allstarlink.org/u/KC2NJV)\ **Post date:** [November 5, 2024, 8:51pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/4 "2024-11-05T20:51:35Z")
As I said, that wasn’t the issue, but no knowing, I tried one aspect to another… ---
**Author:** ![KC2NJV](https://community.allstarlink.org/user_avatar/community.allstarlink.org/kc2njv/32/3634_2.png) [@KC2NJV](https://community.allstarlink.org/u/KC2NJV)\ **Post date:** [November 5, 2024, 8:53pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/5 "2024-11-05T20:53:52Z")
450.000 100/100 and I had no issues for several months… Thought about that, one reason I turned off the Hat. If it went away, then its the Hat, and I would change the freqs to see if something is interfering. It could be its placement in my house (I moved it, which may coincide with the issue, but am unsure). ---
**Author:** ![Mike](https://community.allstarlink.org/user_avatar/community.allstarlink.org/mike/32/1569_2.png) [@Mike](https://community.allstarlink.org/u/Mike)\ **Post date:** [November 5, 2024, 9:27pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/6 "2024-11-05T21:27:38Z")
Could it be that RF is getting on the COS line ? or that theshhold voltages on the line are close ? If you are using CTCSS/DCS, I would also do a test on local LED lighting Just some ideas to chase. ---
**Author:** ![KC2NJV](https://community.allstarlink.org/user_avatar/community.allstarlink.org/kc2njv/32/3634_2.png) [@KC2NJV](https://community.allstarlink.org/u/KC2NJV)\ **Post date:** [November 5, 2024, 9:45pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/7 "2024-11-05T21:45:57Z")
I think I have some play in where I can put the hat, but I have it hardwired to a GB switch with a “short” cable… ---
**Author:** ![N8EI](https://community.allstarlink.org/user_avatar/community.allstarlink.org/n8ei/32/4254_2.png) [@N8EI](https://community.allstarlink.org/u/N8EI)\ **Post date:** [November 5, 2024, 11:25pm UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/8 "2024-11-05T23:25:38Z")
> [@KC2NJV](#): > > 450.000 Just so you know, transmitting on 450.000 isn’t legal in the amateur service because the “upper half” of the 25 kHz signal is out of our allocation… ---
**Author:** ![KC2NJV](https://community.allstarlink.org/user_avatar/community.allstarlink.org/kc2njv/32/3634_2.png) [@KC2NJV](https://community.allstarlink.org/u/KC2NJV)\ **Post date:** [November 6, 2024, 1:02am UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/9 "2024-11-06T01:02:16Z")
> Just so you know, transmitting on 450.000 isn’t legal in the amateur service because the “upper half” of the 25 kHz signal is out of our allocation… Great, I’ll lower it by 25 khz, but that may or may not fix the issue… ---
**Author:** ![N8EI](https://community.allstarlink.org/user_avatar/community.allstarlink.org/n8ei/32/4254_2.png) [@N8EI](https://community.allstarlink.org/u/N8EI)\ **Post date:** [November 6, 2024, 1:13am UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/10 "2024-11-06T01:13:05Z")
I’m not sure where you’re located, but are there repeater inputs or outputs on 449.9… ? If there is a repeater on 444.975 and it’s PL is 100 you may be hitting the edge of that transmission. You may find it more reliable to put a hotspot somewhere in 446. I use splinters like 446.1375 and 446.6875. ---
**Author:** ![KC2NJV](https://community.allstarlink.org/user_avatar/community.allstarlink.org/kc2njv/32/3634_2.png) [@KC2NJV](https://community.allstarlink.org/u/KC2NJV)\ **Post date:** [November 6, 2024, 2:04am UTC](https://community.allstarlink.org/t/cos-detected-cant-find-cause/22201/11 "2024-11-06T02:04:04Z")
I looked into the repeaters and P/L’s around me and that isn’t an issue, but again, I’ll change the freq once I determine that the Hat is or isn’t a suspect… Thanks