NXDN Freq. programing help.

[mmilbourne]

Good Evening,

Not sure if this is the correct place to post this question, so please let me know if it is not.

The NXDN reception issues seems to be well covered on this form but I do not think that this is related to that so here we go! we have a school bus company that uses NXDN for its communications. there a three different frequencies that are associated with the company and each one seems to have its own type of traffic on it. so that leads me to think that it is not a trunk system. I have programed them as conventional and seem to be missing a good 70% of the radio traffic and only here the "base" side of the conversation, I here a lot of what sounds like a data burst before it starts to decode the actual voice. when programed as a one freq trunk it shows NX9 in the scanner and TGID 0 has the traffic, I here ALL of the base traffic loud and clear, however I can not here ANY of the individual units.

What am is missing? I am sure its something I am not programing correctly. please help!

 

[hiegtx]

Good Evening,

Not sure if this is the correct place to post this question, so please let me know if it is not.

The NXDN reception issues seems to be well covered on this form but I do not think that this is related to that so here we go! we have a school bus company that uses NXDN for its communications. there a three different frequencies that are associated with the company and each one seems to have its own type of traffic on it. so that leads me to think that it is not a trunk system. I have programed them as conventional and seem to be missing a good 70% of the radio traffic and only here the "base" side of the conversation, I here a lot of what sounds like a data burst before it starts to decode the actual voice. when programed as a one freq trunk it shows NX9 in the scanner and TGID 0 has the traffic, I here ALL of the base traffic loud and clear, however I can not here ANY of the individual units.

What am is missing? I am sure its something I am not programing correctly. please help!

Which agency, at which location. Can you post a link to the license?

I would suggest programming the frequencies as NXDN One Frequency Trunked systems, not conventional. If you use One Frequency Trunked, that should ignore the databurst. Also, that would let you see talkgroups & radio ID's.

 

[mmilbourne]

Lansing, Michigan area (Ingham County)

I know the RAN is not correct. I show RAN5 on the scanner.

all I see for radio ID's is the "1" and that seems to be the base.

Frequency	Input	License	Type	Tone	Alpha Tag	Description	Mode	Tag
152.345		WPXL355	BM	6 RAN	LANSAREA2	General Education Dispatch for Lansing School District Only	NXDN	Schools
157.605		WPXL355	BM	6 RAN	LANSAREA3	General Education Dispatch for Dansville, East Lansing, Webberville and some trip buses	NXDN	Schools
159.720		WPXL355	BM	6 RAN	LANSAREA1	Special Needs Dispatch	NXDN	Schools

 

[mmckenna]

Looking at the license, there's only one channel that is repeated. The rest of them are simplex mobile/base.

From what you describe, that is the classic symptom of a simplex radio system. The base (FB on the license) is likely running from an antenna at a high location/tower and can easily talk simplex to all the mobiles in the buses.
From your location, you can easily hear the base station, but not the buses due to them being closer to the ground and likely blocked from your antenna.


Also, the emission designator on those channels shows 4K00F1W, which is 4.8K NXDN (aka: Very Narrow). Doesn't mean they aren't running 9.6, though.

 

[mmilbourne]

Looking at the license, there's only one channel that is repeated. The rest of them are simplex mobile/base.

From what you describe, that is the classic symptom of a simplex radio system. The base (FB on the license) is likely running from an antenna at a high location/tower and can easily talk simplex to all the mobiles in the buses.
From your location, you can easily hear the base station, but not the buses due to them being closer to the ground and likely blocked from your antenna.


Also, the emission designator on those channels shows 4K00F1W, which is 4.8K NXDN (aka: Very Narrow). Doesn't mean they aren't running 9.6, though.

when I look at the license, does it matter which locations say they are repeated? I am only monitoring the Aurelias Road Location (Lansing)? also it strikes me as strange that they are not repeated, they cover the whole county.

as for the 9.6 and the 4.8 does that make a difference in the scanner, I defiantly see one of the frequencies as a NX9

 

[hiegtx]

Looking at the license, there's only one channel that is repeated. The rest of them are simplex mobile/base.

From what you describe, that is the classic symptom of a simplex radio system. The base (FB on the license) is likely running from an antenna at a high location/tower and can easily talk simplex to all the mobiles in the buses.
From your location, you can easily hear the base station, but not the buses due to them being closer to the ground and likely blocked from your antenna.


Also, the emission designator on those channels shows 4K00F1W, which is 4.8K NXDN (aka: Very Narrow). Doesn't mean they aren't running 9.6, though.

Actually, the only "repeater" frequency on the license is in a different county, a fair distance away, so likely not in range. For the OPs county, there are two base, and one 'mobile' frequency.

when I look at the license, does it matter which locations say they are repeated? I am only monitoring the Aurelias Road Location (Lansing)? also it strikes me as strange that they are not repeated, they cover the whole county.

as for the 9.6 and the 4.8 does that make a difference in the scanner, I defiantly see one of the frequencies as a NX9

The frequencies with a station code of FB2 are repeaters. In your specific county, you have two tagged as 'base' (station code FB), and one labeled as MO, for mobiles.

Try the attached file. It has to be 'zipped' (compressed) to post in the forums. Download it to your PC. Then, using Windows Explorer or File Explorer, find the file you downloaded , right click on it, then select "Extract" from the choices that come up.

The extracted file, Dean.hpe, can be imported into Sentinel, into the Favorites list of your choice. I have all three frequencies for your county loaded. The site names for the two FB frequencies are the city (Lansing), and the individual frequencies. The third 'site' is for the mobile units.

Ideally, if you have ProScan or ARC536, try logging activity on the system I exported. That may show you how many talkgroups (if more than one) are in use, The radio IDs would also show, Maybe, it's just a radio number. But, if you're lucky, maybe the radio IDs will show up with an 'alias', such as the bus number, or a person's name (like a supervisor). I have two NXDN trunked systems in my area. Both of them display aliases for the radios in use. FD Engine number, law officer's name or patrol unit number, for example.

You're not likely to hear much, if anything, nights or weekends, but weekdays, with the schools insession, they may be fairly active.

 

[mmckenna]

There ya go, what ^he^ said.

They are running a base station at that tower site, not a repeater. If they are just talking from bus to base station or base station to bus, they don't need a repeater. Only reason they'd need a repeater would be if they were trying to do bus to bus communications.
Saves money, and they may not want bus drivers carrying on conversations with each other.

 

[mmilbourne]

@mmckenna @hiegtx thank you for your help, I added it to my profile and will see what that gets me. This system is EXTREAMLY busy in the mornings and afternoons so I will know by tomorrow morning for sure. I do think the one sided audio is due to it being a simplex system

 

[hiegtx]

@mmckenna @hiegtx thank you for your help, I added it to my profile and will see what that gets me. This system is EXTREAMLY busy in the mornings and afternoons so I will know by tomorrow morning for sure. I do think the one sided audio is due to it being a simplex system

Unless you are really close, if the drivers are using portable (hand held) radios, the distance that they are in range (for you) is much less, than if they were using antennas mounted on the roofs of the buses. Even with 'rooftop' antennas, that is still going to limit your reception range. Range for the base unit (dispatch) would be greater because the antenna is on a tower almost 100 ft. tall (per the license).

 

[mmilbourne]

I was logging this morning, over 300 hits, on all three frequencies all with a TGID of 0, 99.9% of the traffic was the base reaching out to buses for information. looks like I just cant here the mobile units because of the simplex setup. thanks for all your help!

 

[werinshades]

I was logging this morning, over 300 hits, on all three frequencies all with a TGID of 0, 99.9% of the traffic was the base reaching out to buses for information. looks like I just cant here the mobile units because of the simplex setup. thanks for all your help!

It's been documented since the x36hp series, problems with NXDN OFT. I tested many years ago by running 2-536hp's on the same antenna, one running OFT with TGID of 0, the other Conventional. 7 out of 10 transmissions that the Conventional set up scanner was receiving, the OFT scanner set up and didn't stop on the activity. I don't know if the scanners/firmware "skip" TGID's of 0, or something else happens. This may or may not apply to your situation, but just a reminder if anyone else is trying to monitor NXDN Conventional systems and is having problems and is using an x36hp or SDS scanner.

 

[mmilbourne]

It's been documented since the x36hp series, problems with NXDN OFT. I tested many years ago by running 2-536hp's on the same antenna, one running OFT with TGID of 0, the other Conventional. 7 out of 10 transmissions that the Conventional set up scanner was receiving, the OFT scanner set up and didn't stop on the activity. I don't know if the scanners/firmware "skip" TGID's of 0, or something else happens. This may or may not apply to your situation, but just a reminder if anyone else is trying to monitor NXDN Conventional systems and is having problems and is using an x36hp or SDS scanner.

Noted, Thank You. its funny because it is working a lot better with OFT than Conventional. however with it being simplex.... that is the issue I am having.