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Worcester Radio Systems Issues Continue

ThePhotoGuy

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Looks like the interference issues with the Worcester County Radio System continue.

Problems Continue For County’s New Radio System
Aug 08,2019 by Charlene Sharpe

SNOW HILL – Problems continue to plague the county’s $5 million public safety radio system.

The Worcester County Commissioners this week gave staff conceptual approval to move forward with re-banding frequencies for the radio system. New frequencies are expected to address interference problems the radios have experienced.



Previous thread that is now closed that discussed it before: Worcester County
 

maus92

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Yikes. I wonder if these fixes will solve it.
-Firebal
Part of the consultant's recommendations was rebanding / changing frequencies if the tropospheric ducting interference with Tidewater VA was not solved by adding the tower site near the airport, and / or changing antennas. They needed to wait until summer when the conditions when the phenomenon typically occurs.
 

maus92

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The subject was discussed for about 30 minutes at this hearing:
Starts about 1:11:15 in the Chief Administrative Officer: Administrative Matters (Part 2 of 2) section.

There were several major incidents where poor radio system performance were noted. One of the incidents was a building fire in Ocean Pines (the area of prior poor service) where radio transmissions could not get out of the interior of a building (basement and attic.) I'm not so sure if this is being caused by tropospheric ducting - it sounds more like expecting a portable radio to reliably hit a tower site in a system that only has six sites for the entire county. I'm not convinced rebanding will solve this particular issue. Sounds more like the county needs to be investing in DVRS for its vehicles.

Another incident alleges that 3 different subscribers from 3 different vendors could not be heard. That was used as an example that "it's not the radios," which may be true - but maybe not. Although interference from VA Beach could very well be be blanking out the transmissions, the frequencies in use by both systems are always changing over a short period of time - were all three radios used within seconds of another? (while both systems were using the same frequency?) . Not so sure about that.

I remain skeptical that the county built a system that meets the expectations of its users. It cost $5M, which is a fraction of what other jurisdictions spend to achieve robust portable in-building coverage.

Also noted in the meeting that Ocean City also has a tropo ducting issue on its system (not sure if it's on the 700 or 800 site,) but apparently they actively manage the problem by manually disabling frequencies that are experiencing interference. Ocean City has a two site, 4 tower system (3 for the main site, and one for the backup site in Ocean Pines.)
 
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WNZT398

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Also noted in the meeting that Ocean City also has a tropo ducting issue on its system (not sure if it's on the 700 or 800 site,) but apparently they actively manage the problem by manually disabling frequencies that are experiencing interference. Ocean City has a two site, 4 tower system (3 for the main site, and one for the backup site in Ocean Pines.)

Ocean City managed interference on the old analog "EDACS" system for many years by taking channels out of service when needed. Ocean City licensed six 700MHz channels to design and build the replacement P25 simulcast system "in town". Five of the best 800MHz channels were kept and used to operate on the inland "Ocean Pines" system/site. The Ocean Pines system/site is not a backup system as it was with the analog system. It is now a full-time part of the ten site P25 network including both Worcester County & Ocean City sites. I manage the Ocean City system and work directly with Worcester County staff related to the management of the Worcester system. The Ocean City system has little to no know or reported interference issues with the 700MHz channels or the Ocean Pines 800MHz channels. Users
have reported some radio issues when out in the county and registered on the Worcester portion of the system.
 

maus92

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Very interesting clarification of the situation. In the referenced commissioner's meeting, the ES representatives stated that Ocean City has 2 staffers that actively monitor the system and manage the frequencies in use, while Worcester does not. Their testimony implied that OC was experiencing similar (levels of?) interference. In describing Ocean City's Ocean Pines site, I was using my understanding of its purpose from when it was original placed in service on the EDACS system when Iived in OC during the summers - I assumed it was running as a "hot" spare in the current design. It is also my understanding that the county's system design was not relying on OC's Ocean Pines site to provide coverage in the county, but seems logical that it would at least fill in where the WC simulcast wasn't providing adequate coverage.

* * * *

Expanding about what was discussed in the meeting and not directly related to Ocean City's system:
The ES managers stated that 7 of their 8 channels are shared with VA Beach roughly ~90 miles south, with 4-5 of the those channels being responsible for 90% of the interference that the system experiences. The commissioners wondered why rebanding wasn't undertaken during the new system design because the county knew they were having interference problems with the old system using the same channels (seems to be a reasonable question.) The ES managers want "conceptual" permission to pursue rebanding. They estimate the cost to be about $5,000 if done in house; and "hundreds of thousands" if done by contractors. This does not include the actual costs of implementing, which would involve site tuning, reprogramming of 1,800 subscribers, and replacing necessary equipment.
 
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WNZT398

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In the referenced commissioner's meeting, the ES representatives stated that Ocean City has 2 staffers that actively monitor the system and manage the frequencies in use, while Worcester does not.
Both systems report alarms during interference. Ocean City has an "In House" radio shop to support the users radios, dispatch center and level-1 system maintenance.

Their testimony implied that OC was experiencing similar (levels of?) interference. In describing Ocean City's Ocean Pines site, I was using my understanding of its purpose from when it was original placed in service on the EDACS system when Iived in OC during the summers - I assumed it was running as a "hot" spare in the current design. It is also my understanding that the county's system design was not relying on OC's Ocean Pines site to provide coverage in the county,
No current reports or documented problems with interference on the Ocean City portion of the system. Your understanding was correct but is now outdated and not correct. Worcester County, from a legal and contract view, is not relying on Ocean Pines site, but the radios have full access to use Ocean Pines depending on how they are programmed and configured in the system database.
The commissioners wondered why rebanding wasn't undertaken during the new system design because the county knew they were having interference problems with the old system using the same channels (seems to be a reasonable question.)
Yes it is fair to ask this question. The answer is that Worcester County had very little problems using the same channels on the old analog EDACS system. Also, the 800MHz band was mature and built out when decisions were made. During the ducting conditions, every available 800MHz channel within 200 miles of the coast had interference. All 700MHz channels, at the time, were issued and unavailable except for six channels that Ocean City quickly acquired because they were having serious 800MHz interference on the boardwalk. Worcester's new system design added twice as many tower sites as the old system and it was reasonable to expect stronger signal levels to overcome the few issues they had in the past. Also it was documented that the old EDACS "ProVoice" digital format did not suffer as bad as an analog radio call. With the new system being all digital, it was reasonable to expect that the scenario would be gone, not get worse.
 

maus92

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Moving forward, I hope they can find alternative or additional channels that are less susceptible to ducting interference. Thinking about it, does operating in TDMA mode make you twice as vulnerable since the tech essentially combines two talkpaths into one channel? Are they talking about leaving the 800 band altogether? I wonder if the system could detect interference, and then adjust channel usage "on the fly" to account for current conditions (when ducting is present and your "neighbor" is using the same channel?) Might be a growth area if not...

Anyway, there seems to be a rush to the rebanding / rechannelization because the FCC has some sort of deadline / meeting coming up in the end of September.
 

WNZT398

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Everybody is working hard to consider all known and available options to resolve this issue. I only wanted to respond to your conclusions and opinions related to the Ocean City system.
:)
 

maus92

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Everybody is working hard to consider all known and available options to resolve this issue. I only wanted to respond to your conclusions and opinions related to the Ocean City system.
:)
I appreciate you chiming in with the facts - accurate information is vital for good governance. And of course understanding the technology. ;)
 

wildbillx

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One of the issues that was brought up can be solved if they follow NFPA 1802 which is all fireground operations should be a simplex frequency. A lot of fire departments on systems think staying on a trunked system is ok, even repeated frequencies have issues while interior. Most of us that use radios in public safety know otherwise.
 

12dbsinad

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There is a thing called simplex for in building fire operations. Why people insist on using TRS or any repeated system for interior work is beyond me. You'll never guarantee interior coverage and there could possibly be system busy outs on a large scale incident.

Stupid, just stupid.
 

maus92

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Doesn't Baltimore County use TRS for interior?
Many jurisdictions in the Washington / Baltimore region use TGs on their TRS's for tactical / in building comms. Montgomery, Anne Arundel, Allegany and I suspect others sometimes use DVRS on their vehicles to bridge between their handhelds and the TRS. Additionally, building codes call for BDAs to be installed in larger / critical building to improve service - but you cannot expect them in residential structures.
 

12dbsinad

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Additionally, building codes call for BDAs to be installed in larger / critical building to improve service - but you cannot expect them in residential structures.
You also can't expect them (BDA's) to work in a compromised structure, building fire, etc. regardless of what the code says. It could work fine during entry, then fail as time goes on. The problem is there is no warning of this nor any real way of knowing other than you key up and your radio all of a sudden doesn't work. WAY to many points of failure between the guy at the end of the hose line and the OIC outside.

OK, off my soap box...
 

maus92

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Some of us never had the luxury of having a portable assigned them.... back in the not so distant past (less than a decade ago,) each vehicle had one mobile and one portable. Some rural departments are lucky to have one radio.
 
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ResQguy

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One of the issues that was brought up can be solved if they follow NFPA 1802 which is all fireground operations should be a simplex frequency. A lot of fire departments on systems think staying on a trunked system is ok, even repeated frequencies have issues while interior. Most of us that use radios in public safety know otherwise.
NFPA1802 says nothing of the sort.
 

zerg901

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How is it possible for a signal from 90 miles away to cause problems to a TRS? Seems nearly impossible.
 

maus92

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How is it possible for a signal from 90 miles away to cause problems to a TRS? Seems nearly impossible.
Tropospheric ducting is caused by temperature inversions or layers of warm air a few thousand feet up, forming during times of high heat and humidity. It is a known phenomenon, more common in the east than the west, and especially in coastal areas. Apparently UHF frequencies in the 800 band can interfere with other stations up to several hundred miles away.Vk4yeh_tropoducting.jpg
 

Dispatcher308

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Hon Land!!!!!
One of the issues that was brought up can be solved if they follow NFPA 1802 which is all fireground operations should be a simplex frequency. A lot of fire departments on systems think staying on a trunked system is ok, even repeated frequencies have issues while interior. Most of us that use radios in public safety know otherwise.
NFPA 1802’s tentative scope is “personal portable 2 way radio communications devices” (subscriber or user radios) for use by the fire service, including structural firefighting, wildland firefighting, and HazMat teams, used inside the “Hazard Zone,” also known as the “Hot Zone,” or the Immediately Dangerous to Life and Health (IDLH) zone. This scope will thus encompass land mobile radio (LMR) 2 way portable radios; future public safety broadband handheld user devices, using LTE (Long Term Evolution) technology and operating on either the Band 14 FirstNet network or Band 14 commercial carrier networks ; and 2 way LMR pagers; as well as the remote speaker microphones for the these user devices. An objective is to have the standard be wireless technology agnostic, but operationally very relevant to fire service use in the IDLH. This scope does not include 1 way portable LMR paging devices, LMR mobile (vehicular mounted) radios, or commercial cellular telephones used by the public (and not within the hazard zone) regardless of technology. This scope does not include land mobile radio (LMR) systems, which is covered in NFPA 1221, Emergency Services Communications Systems, nor does it cover in-building communications systems for firefighters, which are covered in several standards including NFPA 1221 and NFPA 72. This standard also does not cover the issue of radio interoperability. We are not aware of any other standard having the specific scope of NFPA 1802. Purpose: The purpose of this standard is to define the minimum requirements for personal portable 2 way radio communications devices used by firefighters in the IDLH areas encountered in structural, wildland, and hazmat incidents. This standard will include requirements for environmental ruggedness (to include surviving high temperatures and wet environments), intrinsic safety, immediate access to voice communication and distress alarm features, some programmable features, interfaces to certain other devices such as speaker microphones, and ease of use by firefighters in personal protective clothing (PPE) and while wearing self-contained breathing apparatus (SCBA).
 
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