It goes without saying that no assumptions should be made as to the status of the FCI Danbury 3600 system, so if anyone happens to visit the area to verify that this 406.6125 P25 control channel is actually there, please make sure to also verify the status of the existing FCI Danbury system.
U.S. Marshals Service P25 TRS (BEE00-4F0)
- Thread starter dave3825
- Start date
GROL
Member
- Joined
- Aug 29, 2017
- Messages
- 573
At those frequencies it is a phenomenon called tropospheric ducting. Not the same skip propagation as with lower frequencies usually below 60 Mhz (grey area) where it reflects off an upper layer of the atmosphere and back down to the ground. A layer of air in the troposphere will be at a higher temperature than the layer below it. The inversion creates a duct for signals to travel along. I don't recall the exact scenario, but there was a record in which an amateur radio operator on the west coast made a contact in Hawaii (3000 miles) on VHF (2 Meters). Google for records of tropospheric ducting. Wiki article Tropospheric propagation - Wikipedia Tropospheric ducting forecasts. https://www.dxinfocentre.com/tropo.html
However it's very hard to be tropo when someone is sitting under the suspected site with a portable, antenna off, still receiving an S5 or better signal at an RSSI of -55 or better which is the situation we're dealing with here for Site 102.
I still believe it's somewhere on Long Island. Site 102 was DF'ed by my brother as such. It was not heard from NJ, NYC, or Connecticut without pointing a yagi at LI.
GROL
Member
- Joined
- Aug 29, 2017
- Messages
- 573
Someone referred to SKIP, not siting under a tower. I was attempting to inform that the propagation was a different phenomenon which is really neat! It is seldom known about. Tropospheric ducting can be very short or very long distances. But carries higher frequencies that are line-of-sight signals beyond the horizon. This is interesting. E-Skip and Tropospheric Ducting
I will have to take my stuff to Nassau next time I am able. I have a pretty far reach when there is no ducting, even further when there is. When there is none, I can still receive signals from NJ and NYC. Maybe site 102 is low power because only time I receive it is when there is ducting.
What borough are you in and what's your signal report?
Been watching site 122 for a week and nothing going on at all. No affiliations, denials or grants on this site.
Activity on the Randolph site has picked up somewhat this week. Still an extremely boring system, not just because of the almost total lack of activity despite the presence of a bunch of talkgroups (only one of them has more than a dozen hits), but obviously the full encryption in use. I'm not sure why I'm wasting a dongle and multicoupler port on this system. 🤷🏼♂️
The sheer technical joy of getting information?
If someone has the time and will, I was given information that leads me to believe it may be worth checking around the Nassau District Courthouse in the Town of Hempstead for Site 102. Might be a dead-end, but might be worth it.
Last edited:
UNICATIONWAVES
Member
- Joined
- Aug 9, 2020
- Messages
- 127
Are there any sites in Ocean County?
None that have been identified, otherwise they would've been discussed here or listed in the database. If you live in Ocean County, I would suggest searching through the federal VHF and UHF bands to see if you discover any control channels for 4F0.
bs369
Member
I don't know why either.
