Is "ducting" a danger for first responders?

[WB3DYE]

There were four or five instances Saturday morning where emergency responders were unable to reach the county 911 center using their portable radios, according to Delco Emergency Services Director Tim Boyce.
“Proudly, four or five interrupted transmissions is a lot for us,” he said. “We have thousands and thousands of transmissions every day, but any time an officer or a firefighter can’t reach us, we want to know we have those issues. One is too many.”

Interference nixes police radio contact with Delco 911 center

There were four or five instances Saturday morning where emergency responders were unable to reach the county 911 center using their portable radios, according to Delco Emergency Services Director Tim

www.delcotimes.com

 

[CarbyCarberson]

I don't know that I've ever experienced weather-related ducting in Allegheny County to be honest. If it helps, we are using 400 MHz band. There are certain geographic areas that have less-than-ideal coverage, to be sure. Communication is obviously something that is of upmost importance and there are some redundancies in place to reduce anything affecting the ability to communicate with dispatch or with each other on the scene.

If we can't reach the dispatcher via radio, we have a phone number we can call to talk to them directly. This can also be used for sensitive communications. We also have fire tac channels that we can and do switch over to in order to communicate "locally" between ourselves when on a scene that is not monitored by dispatch operations and does not go through the repeater system. This also takes heavy traffic off of the main operations channels when there are multiple events reducing the likelihood that you are going to walk over another transmission.

 

[radioman2001]

This all BS the comment of a new radio system won't fix weather, why is anytime something doeasn't work you need to replace it. Even 7/800 suffer from ducting at times, so buying a new radio system won't fix it.

 

[ecps92]

and the vendors are laughing all the way to the Swiss Bank. Love the "Must move to 700" note...

This all BS the comment of a new radio system won't fix weather, why is anytime something doeasn't work you need to replace it. Even 7/800 suffer from ducting at times, so buying a new radio system won't fix it.

 

[millrad]

How did most police, fire and sheriff departments get by on low band for decades with all the skip interference? The folks at Delco don't really have much to complain about, with occasional ducting interference. I assume they are on an older analog UHF system. Maybe adding a voter and few new receive towers would help.

 

[phillydjdan]

Radioman, are you from the Delaware County area? Let me give you my 2 cents, from personal experience living in the Philadelphia region for 42 years. Delco isn't the only county that has experienced this. Salem, Gloucester and Burlington Counties in NJ have also had the issue, with Burlington still experiencing it and often times losing communication because of it. What's happening is a DTV station in Boston is transmitting in the 500 MHz band, and when conditions are just right, that signal comes across the ocean (believe it or not) and skips right across South Jersey and into Southeast PA. Look at a map and you'll see its a straight shot. Its been well documented. Its also well known that 500 MHz is the only band that this station is affecting down here. Lastly, we have had several counties switch to 700MHz in this area and I have not heard one complaint about ducting in that band in this area. Ducting in 700 is POSSIBLE but far less likely. Putting politics and vendors aside for a moment, any move to any band will help Delco with their problem. Of course, the push from vendors and the FCC is for 700, so that's where they are likely to go

 

[phillydjdan]

Millrad, the current analog conventional repeater system has been in use since the 90s at least. Why waste money on voters that will connect to repeaters that are close to failing? They're already having issues besides ducting on the system. Repeaters are going down. The T1 lines go down. Hell, you couldn't even call 911 from your phone for a couple hours due to a telecom issue! Then factor in the hoodlums that bought Baofeng radios to interfere with the police channels by either keying up in close proximity or keying up and yelling onscene words and its clear to me... They need a new system. Badly.

 

[mikewazowski]

Ducting is possible all the way up into the microwave bands. Common occurrence every spring and fall with warm days and cold nights.

 

[trentbob]

Radioman, are you from the Delaware County area? Let me give you my 2 cents, from personal experience living in the Philadelphia region for 42 years. Delco isn't the only county that has experienced this. Salem, Gloucester and Burlington Counties in NJ have also had the issue, with Burlington still experiencing it and often times losing communication because of it. What's happening is a DTV station in Boston is transmitting in the 500 MHz band, and when conditions are just right, that signal comes across the ocean (believe it or not) and skips right across South Jersey and into Southeast PA. Look at a map and you'll see its a straight shot. Its been well documented. Its also well known that 500 MHz is the only band that this station is affecting down here. Lastly, we have had several counties switch to 700MHz in this area and I have not heard one complaint about ducting in that band in this area. Ducting in 700 is POSSIBLE but far less likely. Putting politics and vendors aside for a moment, any move to any band will help Delco with their problem. Of course, the push from vendors and the FCC is for 700, so that's where they are likely to go

Dan, I'm amazed how often it happens on Burco, all day everyday, it's amazing they tolerate it, if any County needed a new 700 megahertz p2 system it's Burlington. Oh wait, they're setting it up now. LOL... Can't wait.

 

[KK2DOG]

I personally look forward to tropospheric ducting especially on 2-meter SSB.
My best contact was from northern New York to Texas with a small loop and 150 watts.

 

[dsmiley]

FCC 2020 Mandate to move to higher frequency???

 

[n5ims]

How did most police, fire and sheriff departments get by on low band for decades with all the skip interference? The folks at Delco don't really have much to complain about, with occasional ducting interference. I assume they are on an older analog UHF system. Maybe adding a voter and few new receive towers would help.

Most of them handled it pretty easily thanks to training and experience. Since ducting happened quite often, they were taught to not only listen to the words, but also to the person talking. If the person talking didn't sound anything like their local dispatcher and the location(s) weren't in their district, they simply ignored the transmissions. They also listened to other transmissions to see if known local responders were handling the call as a local call or not and reacted accordingly.

Way back in high school, we'd often visit the fire station across the street (typically on our way to the soda shop behind it) where we knew all the firemen. One day, they all were gathered around their bay listening to an active school fire on their low band radio channel, but none of them appeared to be ready to drive off to assist. I asked what was going on and they asked "where, on the radio?". I replied yes and was told not to worry, that was in California and although it sounded very local wasn't something that they would be asked to assist with, chuckling. I asked the station chief about using PL to cut down on the interference and he said two things. 1) "What, and miss all this? It's good training if nothing else." and 2) "PL is only on the bigwigs radios to keep us from hearing their calls and besides, when it's active we can't hear transmissions from the surrounding departments". I started to say something about PL only keeping the bigwigs from hearing them and he quickly cut me off saying "don't let them know that!".

 

[W7FDX]

and the vendors are laughing all the way to the Swiss Bank. Love the "Must move to 700" note...

Plus with the terrain in PA 700/800MHz doesn't work very well, but in Delco where it's more urban it would work better than say a county like Potter or Tiogia. Delco is currently UHF which is a good middle ground between 800 and VHF.

 

[saber2k5]

Delaware County is using analog frequencies in the 500 Mhz range, aka T band. Looking at the surrounding regions that utilize tv frequencies in that range, Charlottesville, VA is on channel 19. I would consider them a primary source of interference too (in addition to Boston on tv channel 20). I base this on personal observations that I often hear NWS broadcasts from VA late at night due to ducting; my listening post is in southeast Delaware County. FWIW-Last weekend the signal from NWS Wallops Island, VA was extremely strong in the early morning hours, completely covering the Allentown NWS broadcast transmitter, which is about 40 miles north of me. Although these are VHF frequencies, the T band seems to have similar propagation characteristics.

 

[millrad]

Millrad, the current analog conventional repeater system has been in use since the 90s at least. Why waste money on voters that will connect to repeaters that are close to failing? They're already having issues besides ducting on the system. Repeaters are going down. The T1 lines go down. Hell, you couldn't even call 911 from your phone for a couple hours due to a telecom issue! Then factor in the hoodlums that bought Baofeng radios to interfere with the police channels by either keying up in close proximity or keying up and yelling onscene words and its clear to me... They need a new system. Badly.

That's why analog FM has been/is being replaced by P25 on older conventional UHF systems. Here is CT, municipalities are being offered the chance to tie into the new massive statwide 700 MHz digital trunked system, rather than have to set up their own. We actually had town still using low band at 39 MHz

 

[WB3DYE]

Here is an editorial concerning the radio issues:

It got so bad that Fraternal Order of Police Delaware County Lodge 27 fired off a letter to its members warning them of the possible outages and again asking for a new system.

Editorial: Officers deserve a solution to emergency communications problems

Delaware County has a problem with its emergency communications system.

www.delcotimes.com

 

[WB3DYE]

Here is a site I use. It gives almost "real time" ducting info VHF Propagation Map

Make sure u zoom in to the area your interested in...Zooning out will not show the conditions

 

[captaincab]

Here is my question for everyone pushing new p25 technology with 3000 to 5000 or 6000 radios. Who is going to step in and help smaller fire departments needing to buy say 15 or 20 portables plus 2 or 3 mobiles and a base station that gets really really expensive really fast and that’s assuming the county keeps the vhf frequency for voice and alpha paging if we switch to 700 or 800mhz forget about it some fire companies are screwed. Plus police departments are a whole other set of issues

 

[prcguy]

I've spend over 40yrs playing with VHF/UHF amateur repeaters and also owning and operating a commercial multiple UHF mountain top repeater business and some GMRS repeaters. Besides the occasional 2m and 70cm amateur tropo openings where nobody is actually interfered with, only once in 40yrs did I have a problem with ducting and a problem on UHF commercial freqs.

I ran several 2 watt UHF splinter repeaters and one in Los Angeles was being picked up in Palm Springs, CA about 125mi away. My repeater was not really interfering with anything but another repeater owner in Palm Springs accused me of running some tremendous power since he never heard me before and all of a sudden my LA customers were being heard in Palm Springs. That particular summer we had a lot of tropo openings in the amateur bands that would explain things, but this guy contacted the FCC anyway and lodged a complaint that never went anywhere.

With that said, it may be possible for tropo ducting to allow a distant system to interfere with very low power radios like hand helds in the affected system, but its usually a short lived problem and the interfering levels are usually quite low.

 

[Para078]

How did most police, fire and sheriff departments get by on low band for decades with all the skip interference? The folks at Delco don't really have much to complain about, with occasional ducting interference. I assume they are on an older analog UHF system. Maybe adding a voter and few new receive towers would help.

When Northeast Texas was on 37.260 daytime communications were hindered by skip from up north. In spring of 1973 it was so bad that a back of scanner antenna would pick it all up.