172.3000 $A70 Control Channel eh?

spacellamaman

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municipality of great state of insanity
just based on how this has played out, i really think this is a far distant, stationary, always on station, so to speak.

the most recent incident of ten minutes involved the signal fading in and out like you might experience with a distant AM broadcast DX. Full strength, clear, then working its way down to nearly gone, then back again. This is all while stationary and getting no significant changes from tweeking antenna position either.

"Ducting",a question for those knowledgeable in this area :

I would like to see if anyone can help me here on the issue of "ducting". the way i imagine the reception of VHF Low-Band Skip is akin to a mortar shell trajectory, just dropping in from above. not much you can do to determine direction of origin using only the signal reception.

with higher frequency "ducting" as i have come to understand it, its more akin to an artillery trajectory. it still arrives in a high trajectory, but still flat enough that direction might be determined to some general degree. thats been my impression. Is that generally correct?

this has forced me to track down, un pack and assemble an outdoor TV antenna https://www.rcaantennas.net/outdoor/?sku=ANT752E i bought a few years back, with the intention of trying to perhaps at least get a cardinal direction if the signal ever re-appears long enough. but it recently occurred to me that i may be operating on a false assumption, and would hate to add spurious info out of ignorance here.
 

ecps92

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Messages
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Taxachusetts
A good site to use for VHF High band opennings is
and it may help for the N/S or even E/W directions you are hearing from.

There are others, but I use this one...easiest
just based on how this has played out, i really think this is a far distant, stationary, always on station, so to speak.

the most recent incident of ten minutes involved the signal fading in and out like you might experience with a distant AM broadcast DX. Full strength, clear, then working its way down to nearly gone, then back again. This is all while stationary and getting no significant changes from tweeking antenna position either.

"Ducting",a question for those knowledgeable in this area :

I would like to see if anyone can help me here on the issue of "ducting". the way i imagine the reception of VHF Low-Band Skip is akin to a mortar shell trajectory, just dropping in from above. not much you can do to determine direction of origin using only the signal reception.

with higher frequency "ducting" as i have come to understand it, its more akin to an artillery trajectory. it still arrives in a high trajectory, but still flat enough that direction might be determined to some general degree. thats been my impression. Is that generally correct?

this has forced me to track down, un pack and assemble an outdoor TV antenna https://www.rcaantennas.net/outdoor/?sku=ANT752E i bought a few years back, with the intention of trying to perhaps at least get a cardinal direction if the signal ever re-appears long enough. but it recently occurred to me that i may be operating on a false assumption, and would hate to add spurious info out of ignorance here.
 

spacellamaman

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Aug 22, 2014
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municipality of great state of insanity
and it may help for the N/S or even E/W directions you are hearing from.

There are others, but I use this one...easiest
i appreciate it, easiest, is what i am looking for :)

yeah, i know N/S E/W ain't much, but it beats than what we have now. being relatively close to the atlantic ocean, central NC, and knowing how active NC folks are here, i feel pretty good i can rule out eastern NC being the source, so that knocks out a good bit of the possibilities, when it comes to using a directional antenna. i would like to think if i could narrow it down to due South, SW, due West, NW or North, while coarse, it would at least give a starting point.

that second evening, while i had no way to check for SC 380mhz systems, i wasn't picking up Shaw AFB, but was possibly getting VaSTARS that aren't normally Rx'able (purely based on hearing digital audio on correct freqs). trying to make a determination of direction, based on simultaneously received stations geographic locations is pretty awful. and with an analog scanner, basically worthless... sheeesh

so does my concept of Ducting sound bout right?
 

ecps92

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Taxachusetts
I've found even tho the map shows N/S, from my QTH it could be more North.

By using the known NWS reception during a normal day, it helps me get an idea of which way the RF is flowing
A Quick tune of surrounding NWS and [for me] Canadian WX - will best help for a direction



i appreciate it, easiest, is what i am looking for :)

yeah, i know N/S E/W ain't much, but it beats than what we have now. being relatively close to the atlantic ocean, central NC, and knowing how active NC folks are here, i feel pretty good i can rule out eastern NC being the source, so that knocks out a good bit of the possibilities, when it comes to using a directional antenna. i would like to think if i could narrow it down to due South, SW, due West, NW or North, while coarse, it would at least give a starting point.

that second evening, while i had no way to check for SC 380mhz systems, i wasn't picking up Shaw AFB, but was possibly getting VaSTARS that aren't normally Rx'able (purely based on hearing digital audio on correct freqs). trying to make a determination of direction, based on simultaneously received stations geographic locations is pretty awful. and with an analog scanner, basically worthless... sheeesh

so does my concept of Ducting sound bout right?
 

freqhopping

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Lo Co VA/ FM19
The JNCR 380Mhz system Joint National Capital Region Trunking System, Various, Multi-State - Scanner Frequencies is what I use as an indicator of improved propagation conditions. When my range roughly doubles there is usually an improvement on VHF and sometimes even 800Mhz. When conditions improve I receive distant sites to the east and southeast.

One thing that really improves conditions is thunderstorms passing through after a hot day.



A good site to use for VHF High band openings is
Sites like this have never been representative of the conditions I'm actually experiencing. Right now it shows there should be enhanced propagation in my area, yet I'm not experiencing that.


Make good notes of the weather conditions at your location and the surrounding 200 miles when you receive distant signals, then watch for those conditions in the future.
 

freqhopping

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Lo Co VA/ FM19
"Ducting",a question for those knowledgeable in this area :

I would like to see if anyone can help me here on the issue of "ducting". the way i imagine the reception of VHF Low-Band Skip is akin to a mortar shell trajectory, just dropping in from above. not much you can do to determine direction of origin using only the signal reception.

with higher frequency "ducting" as i have come to understand it, its more akin to an artillery trajectory. it still arrives in a high trajectory, but still flat enough that direction might be determined to some general degree. thats been my impression. Is that generally correct?
This site covers it.

 

spacellamaman

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Aug 22, 2014
Messages
614
Location
municipality of great state of insanity
I've found even tho the map shows N/S, from my QTH it could be more North.

By using the known NWS reception during a normal day, it helps me get an idea of which way the RF is flowing
A Quick tune of surrounding NWS and [for me] Canadian WX - will best help for a direction

Considering I use NWS daily during some parts of the year, like now for Wx reports/forecasts (being w/o a smartphone, I party like its 1999, 24/7), you would think that would have dawned on me already. i do use NWS station Rx as a measure of how good a locale is for omni Rx (1 station Rx=blech../7 Station Rx =Hot Dog!) but haven't thought much about variability at all.

i guess its just cause basically every ducting Rx is of a known quantity and infrequent. This being the only unknown, and very infrequent. At least this gives me some better tools to work with if it happens again sometime.


Make good notes of the weather conditions at your location and the surrounding 200 miles when you receive distant signals, then watch for those conditions in the future.
regret i haven't already


yeah thats probably the best tutorial i've seen yet, the pictures are certainly helpful too. the mountain ranges blocking i hadn't thought about either, providing more complication....yyeeeaaa!
 

spacellamaman

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Aug 22, 2014
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o_O

Alright boys, now i know last years fourth was a disappointment for all of us. so i ... no..no..calm down boys.. now you might not be crazy about what i have here, its not explosive in the traditional sense, but it does have some......pop....

*big Efn grin*

and the best part is....we don't have to tell your mom about it!

so here goes!!!

---------------------------------------------------------------------------------
Central NC, 7/4/2020, 0330-0430h local.

BCD436HP-stock

P25 system with one site, one control channel programmed:

172.3000

Analyze mode:

Sys ID: 0A7Fh-001
Site: 001
WACN: BEE00h
NAC: A70h

---------------------------------------------------------------------------------
See that was pretty cool wasn't it boys???
Whadda you mean "Mom would probably approve"?!?!?
Whats that supposed to mean?!?!?


Happy 4th of July to all and to all a big BOOM!
 

spacellamaman

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Messages
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municipality of great state of insanity
Sys ID: 0A7Fh-001
Site: 001
WACN: BEE00h
NAC: A70h

i must say i feel my apocryphal anecdote may have caused confusion in coloring the nature of the entire post.

the above named system was received in the wee hours of July 4th (3-4am-ish) as well as the final hours (4th-10pm to 1 am on the 5th, approx) with the final 3 hours being run in Discovery mode, not surprisingly with no hits/activity.

as far as clues to where this originates, i have some vague elements to pass on, of unknown level of utility for now at least.

-High elevation above all surrounding terrain has been necessary so far, at least 100ft, to have a chance of steady reception.

-based on location best received, with high ground to my rear/northern arc, possible direction of origin is likely in a southern arc from 90 degrees to 270 degrees, very approximate.

-concurrent reception of Shaw AFB CC 163.4125 was notable due to being in the 4-5 bar range the whole time during the 10pm to 1am occasion.

-the signal is subject to wide variation in signal strength, from nothing, to 2-3 out of 5 bars signal strength on a 436hp. after it got to the steady 2-3 bars range, in these two instances it stayed there for some time, later than i could observe. the fading, however confounds any confidence as to determining direction based on LOS radio horizon.

its going to be a while til i can revisit this location, which provided the best reception so far of any occasion, but will report back if anything more can be determined elsewhere.
 

ChrisP

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Messages
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Portland, OR
Thanks very much for capturing this information! Obviously further research is required.

Also to clarify some of your information:

The System ID should be 0A7. The lower case "h" is Uniden indicating that it is a hex value. Same goes for the site NAC, which is $A70.


- Chris
 

ecps92

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Messages
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Taxachusetts
OR is it A7F ??
which aligns more with the $Axx NAC's
Thanks very much for capturing this information! Obviously further research is required.

Also to clarify some of your information:

The System ID should be 0A7. The lower case "h" is Uniden indicating that it is a hex value. Same goes for the site NAC, which is $A70.


- Chris
 

spacellamaman

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Joined
Aug 22, 2014
Messages
614
Location
municipality of great state of insanity
Thanks very much for capturing this information! Obviously further research is required.

Also to clarify some of your information:

The System ID should be 0A7. The lower case "h" is Uniden indicating that it is a hex value. Same goes for the site NAC, which is $A70.


- Chris
OR is it A7F ??
which aligns more with the $Axx NAC's

much obliged gentlemen, i felt it was best if i just gave a direct transcription of the info, as a general practice and just in case some other info could be derived from what little there was.
 
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