Kern County Fire narrow band change starts

[dmd911dispatcher]

Ok here is the scoop straight from the radio techs doing the reprogramming. The new Kern-1 (153.785) is staying wide band. The new Kern-2 (155.880) is going narrow band. Kern Tac-3C 158.7375 is narrow band as is Kern Tac-5C 151.1375. We also have converted 3 UHF channels to narrow band. 453.225 the Mutual Aid channel, 453.450 Ag Department and General Services, and 453.700 County Parks and Waste Management are all narrow band. Fire will convert 2 more channels to narrow band hopefully next year. Sorry for the confusion. I guess I was a little bit behind the times with the information I had been given.

 

[zerg901]

Someone from the UK posted to the PWF list. He said that the UK went narrowband back in (?1990). There were folks saying that the range would be diminished, but somehow, it all worked out OK.

If Kern County was in the UK, Germany, France, or Italy, I suspect that the City/County structural FD would have : 1 paging channel, 1 response channel, and a bunch of short range walkie talkie channels. The forest fire units would probably have a few freqs of their own. (This is based on the limited amount of info that I have been able to dig up over the years).

There are many aspects to the question of narrowbanding. Repeater site placement, use of simulcast, licensed but unbuilt radio systems, radio procedures, operational procedures, etc. A simple example of this would be - if one system aired a dispatch message 4 times, and another system aired the dispatch message only once, which radio system do you think would suffer from a 'lack of airtime'?

Thanks for the good discussion - Peter Sz

 

[PJH]

The reprogrammed fire radios will display a Kern 1W for the wide channels. My understanding is that all of the equipment is narrowband capable, but just the logistics of reprogramming all the field radios takes some time.

There has been some intermod on the tac channels that have hastend this, but from what I have gathered, this has been in the works for some time.

As funds become available, the long term goal is to elimate the two-tone alerting and go with a Zetron system similar to what Bakersfield City Fire has...but, don't expect it too soon (due to funding).

The county has a fairly nice and modern system, so don't expect a mass garage sale of equipment. Majority of the radios are MTS2000/MCS2000's, BK's (more for wildland incidents) and a fairly new Harris MW system. Quantar repeaters and Centracom Gold Elite consoles make up the backbone. BFD has some XTS radios. KCSO is also purchasing XTL mobiles.

 

[Eng74]

The Zetron system is at all the stations already. They are on the microwave system and I want to say there are two stations that are not in the microwave loop. Getting them in on the loop will be a feet since they are in the mountains so it will take a couple of tall repeaters to get them in line. I like haveing the tones outs on Kern 1 makes the Uniden tone out worth having. As for reprograming the the radios figure there are about 500 plus radios to reprogram over an 8000 square mile county with atleast 8 radios or more per station it takes about a month. The radio guys will spend more time on the road than the time it takes to program them. Time for a county tour.

 

[zerg901]

http://blog.tcomeng.com/index.php/2007/narrowband-analog-conversion-a-case-study/

FYI - this article says that skinny band radios are as goodly as portly band radios - can I get an amen?

That article contains info on the South San Francisco CA PD radio system, and the Burlingame CA PD radio system. (2007 & 2008 info)

Peter Sz

(PS - I posted the URL for the NTIA study on spectrum squeezing - I think I put it in the Firefighters Loosing Faith in Digital thread. I also have a URL to dig up on narowband for maritime use - standby please - here it is - http://www.ntia.doc.gov/osmhome/reports/tr97343/tr97343.html
- reportedly from 1997 - apparently they found that narowband would work fine in the maritime VHF bands.)

 

[SCPD]

The first link involves an area of only 9 square miles where there are three voting receivers installed. The topography of South San Francisco is very mild, to say the least. The average National Forest is around 3100 square miles, and in the western U.S. the terrain is usually anything but mild. I had indicated that coverage problems existed on the Mendocino National Forest in northwest California when they went to narrow band, but haven't heard what the experience has been on other National Forests. In my experience there are a lot of areas in the mountains that have very marginal coverage, where a small change in signal strength will result in getting through or not.

One thing I've noticed with narrow band is the very low audio, not just in comparison with wide band systems, but how it performs in marginal conditions. It often sounds fine as far as minimal background noise, but is hard to copy even when the volume is turned all the way up, due to low audio.

The last study by the NTIA involves maritime use and again the terrain, or lack there of, is the biggest difference between the environment of that study and actual experience of agencies like the U.S. Forest Service. I would be interested to see a study done in large mountainous areas as my information is all anecdotal.

 

[zerg901]

Maybe a good rule of thumb would be to use wide band for wide area systems, and use narowband for shorter range comms. Peter Sz

 

[KMA367]

Narrow and wide and where?

One thing I've noticed with narrow band is the very low audio, not just in comparison with wide band systems, but how it performs in marginal conditions. It often sounds fine as far as minimal background noise, but is hard to copy even when the volume is turned all the way up, due to low audio.

You've probably seen these already (they're a couple years old), but the audio problem is particularly serious when trying to listen to a narrowband transmission with a wideband-only radio, and vice versa:

This 2005 NMAC SafeNet advisory mentions that:

• Wideband radios operated in a predominately narrowband environment may be much louder (loud deep voices seem to be problematic), “choppy”, inaudible or distorted with feedback.

• A narrowband radio transmitting to a wideband radio may sound very soft and quiet in comparison to a wideband transmission.

• Repeaters, used in a mixed mode environment, may lock open, then reset; effectively stopping all transmission for up to three minutes​

And the USFS issued this "Aviation Safety Alert" which addresses several issues including the above repeater problem "Some new repeater equipment is very sensitive and if a radio that is in the wideband mode transmits to a “narrowband repeater” it may result in an inaudible or distorted message. In some cases the repeater may “lock-up” allowing no transmissions until the preset “time-out” period for the repeater expires (1-3 minutes)."

Maybe a good rule of thumb would be to use wide band for wide area systems, and use narowband for shorter range comms. Peter Sz

That might, in many cases, bring about the exact opposite of what's trying to be accomplished - getting more usable frequencies - by going narrowband. The topography is generally a more critical factor than the area, everything else being equal (which it never really is, of course).

Especially in the So Cal Basin, or in the mountains surrounding the Central Valley, there can be numerous incidents within radio line-of-sight of each other, and they often run out of enough discrete frequencies and repeater pairs. So in these "wide areas," narrowband's twice-as-many frequencies may be the best solution, if they can resolve the range and penetration issues. Just as digital has shown itself to be not as robust as analog in some cases (like LAPD and others), hopefully narrow analog can be refined and improved as its usage expands.

 

[KMA367]

http://blog.tcomeng.com/index.php/2007/narrowband-analog-conversion-a-case-study/

FYI - this article says that skinny band radios are as goodly as portly band radios - can I get an amen?

Thanks for that link, Peter. I'd like to see some empirical information about the subject. No question that more radio frequencies are needed, especially in congested areas, but I haven't seen much information about why narrowband digital is so much better than narrowband analog for public safety radios, where literally any message may be a matter of life or death. I've heard that with digital, data can be sent along with voice on the same frequency, but is that so important? Or is there more to it than that?

 

[PJH]

Skimmed over some stuff here...

But if you are going to be using a narrowband system, then your going to be using narrowband radios. Your not going to be using wideband radios on a narrowband system and vice versa.

Properly programmed radios work just fine. Commerical radios have been required to be narrowband compliant for some time now and its just a programming step.

As a user and of several and helped to implement some, I don't know what the big deal is.

 

[MCIAD]

The big deal is this - not everybody is using modern, narrowband capable, radios.

I am on the Statewide Firescope Communications Specialist Group, and this topic comes up just about every meeting.

Small Volunteer Departments most often have outdated, non-NB radios, and almost always lack the funds to upgrade. Then, when they get called for a Mutual Aid request somewhere where there is narrowbanding (i.e. any Federal Forest area), there is a conflict.

Another area of concern - I am a certified Incident Communications Manager, and spend time evey summer out at the Campaign fires around the state. Almost without fail, we get private contractors (Dozers, Water Tendeers, etc.) that come to the fire with old Bendix King LPH and early EPH radios, that can not be programed for NB or split frequencies (which are not neccessarily the same thing). These radios get rejected outright, or at least they should, and if we have them, a radio is checked out to them from the cache. Of course, often we have no radios to provide them, so either they get demob'd and sent home, or get sent out to the line without a radio (*very bad*). Worse are the contractors who know their radios are not capable or authorized to use, but hand program them off the ICS-205 that is in the IAP, and go out anyway. This can, and has, cause all kinds of issues - especially under emergency situations.

I am not sure what the solution is - nobody is. It comes down to Safety vs Cost vs Personal/Department desire. If somebody figures it all out, let the rest of us know . . .

Stepping down from the soapbox now.

 

[trooperdude]

As an example of the radio situation we went together with other volunteer departments on a regional grant application spanning 3 counties.

It was a total quote of >$200K to upgrade mobiles, hand-helds and pagers to narrow band. Not even P25 compliant /\/\ equipment either. Just to maintain current capability.

With most volunteer departments that is an entire LIFETIME of operating budget.

Especially with fuel approaching $5/gal for diesel and rising OSHA compliance costs.

And congress cut the AFG funds by half again this year. :evil:

 

[ScannerDude244]

As an example of the radio situation we went together with other volunteer departments on a regional grant application spanning 3 counties.
:

That's what Monterey county did
Rep. Sam Farr, D-Carmel, on Friday will join members of the Monterey County Fire Chiefs Association, the Monterey Fire Department and the Salinas Rural Fire District to celebrate two federal grants totaling nearly $1.5 million.
The funds have been used for 700 portable radios and 230 mobile radios. TK-5210 portables and TK-5710 mobiles

If more volunteers departments came together and did what you guys did it would save them a lot money, and make sure you have a good writer

 

[citylink_uk]

We've had 12.5KhZ spacing for 20 years and have had no problems.

 

[PJH]

I was going to post something awhile ago... but most of the issues that you hear about with narrowbanding, and with people who have no clue on what they are talking about...

is that you CANNOT use a 25 radio on a 12.5 channel and expect it to work. Thats just common sense. If you use a 12.5k radio on 12.5 system, your fine (or a radio that supports both AND properly programmed to 12.5)...

Its like using a metric socket on a non-metric nut and trying to get it off without problems.

 

[WayneH]

Totally OT, but,

Sprint is moving away from Iden they have been working with Qualcomm chip maker to make qchat Push-to-Talk.

Sprint is not moving away from the iDEN network any time soon. It's going to be around for at least a year or two if not longer. Qchat will be cross-compatible with Nextel Direct Connect. I just saw a demo of it the other day.

 

[PJH]

What is really neat, that I have played with (and this was a few years ago)... was a Nextel PTT <> P25 9600 <> simplex digital <> Conventional repeater interconnect, all from Motorola. Pretty snazzy, but out of the price range for my department

 

[Eng74]

The patch between Kern 1 and Kern 2 is done. All dispatches will be on Kern 1 and Kern 2 is usable again.

 

[1979lee]

The patch between Kern 1 and Kern 2 is done. All dispatches will be on Kern 1 and Kern 2 is usable again.

Thanks for the update eng74, to be clear on this, kern 1 is 153.785 pl 167.9.,correct?

lee

 

[Eng74]

Thanks for the update eng74, to be clear on this, kern 1 is 153.785 pl 167.9.,correct?

lee

Yes that is right. I think everyone got used to having Kern 2 to use when their normal channel was in use you couldn't go to Kern 2. There was a couple of time they wanted Batt 7 calls to go to Kern 4 and we will not work out on the desert since it is too near to Ridgecrest PD's channel.