Thread: 800 MHz radio systems
06-15-2001, 02:05 PM #1oldE6manFirehouse.com Guest
800 MHz radio systems
The failure of the 800 MHz radios in Delaware is a sobering reminder to any jurisdiction using or contemplating 800 MHz radios. Does your dept. use 800 MHz? What is good/bad about the system?
06-15-2001, 02:53 PM #2Scottie SchmidtFirehouse.com Guest
hi, why did they not blow the air horns when the emerg evacuate was ordered?
Scottie Schmidt JR (junior fire fighter
06-15-2001, 04:28 PM #3jizumper-5Firehouse.com Guest
I have worked with the 800MHz system for about 2 yrs now. We experience some of the same issues. The fact is that the higher in frequency you go, the less permeable the signal becomes to objects (like concrete). The only way to over come this is more power or more repeater stations. The key is if you can hit the repeater! These systems need a middleman to talk from unit to unit. VHF/UHF it is direct communication. Granted on the units we use, there is a talk around (I believe it is required of all 800MHZ systems) or "conventional" bank of channels. We were told that if we do not hit the repeater we could talk unit to unit. So far when we have had lost communications in buildings, that has worked for us.
There are many advantages (to many to list) of this type of system. It is more flexible that standard (VHF/UHF) system. By this I mean more information over a given frequency can be sent, and you can gear it so people from many different agencies or from different regions (if they have an 800MHz) system can talk. If you have enough repeaters, one could ideally talk from "coast to coast".
Hey everything new has its bugs. They just need to be worked out. Hopefully it doe not cost a life to do so. Just my 2 cents.
[This message has been edited by jizumper-5 (edited 06-15-2001).]
06-15-2001, 05:03 PM #4hfdfaoFirehouse.com Guest
My department has switched to an 800mhz trunking system, in conjunction with all of the Towns in our surrounding county. We too have had some problems with talking out of buildings. The problem is not a question of power. If you compared the wave form of a low band radio(33.000mhz) to the wave form of and 800mhz radio it would be similar to this. If the low band wave form was 3" in height, it would be spread out and very loose. The 800 wave form would be about .5", and very compact..Because of this the 800 has great penetration, but no legs to hit a repeater some distance away. Low band can talk for miles(ie. skip), but doesn't always penetrate well. This was all explained to me by a Cambridge MA Deputy Chief, granted its a little over simplfied, but it gets the point across.
We set our system up so that our trunked talkgroups also scan a direct channel. This way if you can't access the repeater, you just switch to the direct channel and start talking, everybodies radio is scanning so you should be heard.
Its not a perfect system, but its works better than what we had.
May your vents be leeward, your searches be negative, and your overhaul complete......
06-15-2001, 05:42 PM #5Dalmatian90Firehouse.com Guest
All radio systems need to be engineered AND built AND monitored/maintained properly.
800mhz has the advantage of "pentrating" buildings better (actually, the short waves bounce nicely in buildings and find opening/exits to go through). But reduced range means repeaters need to carefully located.
Trunking adds complexity, as now the radios are constantly switching their actual transmit/receive frequency.
If you add Digital capability, design is even more critical -- Digital systems are either clear and there, or don't work. At least analog systems you *might* still be able to make out enough of the weak transmission. Digital systems give you security, and pack a lot more channels in the space then just plain trunking.
The largest downfall of 800mhz trunked systems is when their designed properly, and then the State or Municipality goes, "Great system, but we can't afford it. Where can we skimp?" Delaware is an example -- they throw up a repeater to cover a gap in coverage (gap being problem #1), and the repeater isn't monitored so they didn't know it was out of service (problem #2). Both money issues.
If I had to design a system...
-- I like UHF or 800mhz since they do better than VHF-hi or VHF-low in getting out of buildings.
-- There should be no more than 4, maybe 6, channels on a Walkie-Talkie so you can figure out where you are in the dark, with a gloved hand, in an emergency.
I'd break the channels up as:
Channel 1 -- UHF Region-wide fixed repeater
Channel 2 -- UHF Simplex
Channel 3 -- UHF Duplex via Mobile Repeater (You can hear & talk to anyone on the fireground on 3 or 4, and when you talk it goes through the Mobile Repeater so Dispatch hears you to. This is the "Chief's Frequency")
Channel 4 -- UHF Simplex on Mobile Repeater Transmit Channel (You can hear and talk to anyone on 3 or 4 around the fireground, but can't key the repeater. But you still hear communications from Dispatch that are being rebroadcast by the mobile repeater.)
Normal fireground operations, you use #4.
Need dispatch? Goto #3. Usually Chief officers stay on this, or other officers in an emergency when the Chiefs aren't answering.
Special op you don't want to clutter up the radio with, like Water Supply or Fire Police? Head over to Channel 2.
Need to contact mutual aid coming in that hasn't shifted to Channel 3/4 yet? Goto Channel 1.
Keep It Simple!
06-15-2001, 07:56 PM #6Captain GonzoFirehouse.com Guest
My Department's communications are on the 800 Mhz frequencies. We haven't had any problems. The key is the number of repeaters in the community. When New Horizons (an assisted living facility) and the Solomon Pond Mall were built, one of the provisions was the installation of a repeater for the comm system. We have other repeaters in various locartions in the city. We also have the Police frequencies in the radios, so we can talk directly to the PD or monitor their transmissions.
No radio system is perfect...hence one of Murphy's Laws of Firefighting....
Radios always seem to go dead or cannot transmit or receive at the worst possible moment.
Our paging is still done on 46.42 Mhz for now, we are going to alpha pagers shortly. We still have the low band radios in the stations and on the rigs to communicate with the neighboring communities and the District.
Firefighters: Today's heroes protecting everyone's tomorrows!
[This message has been edited by Captain Gonzo (edited 06-15-2001).]
[This message has been edited by Captain Gonzo (edited 06-16-2001).]
06-16-2001, 12:39 AM #7ff21Firehouse.com Guest
my dad dept uses 800 trunked system
why did clarmont not do daily radio checks
and why did thery not hit the airhorns
in my dept we hit the airhorns and the serin is set on hi lo that is the only time we are supposed to use it on a scene
stay safe and have fun
06-16-2001, 11:18 AM #8WillBFirehouse.com Guest
I thought the article said they DID hit the horns but the FFs didn't hear them
06-16-2001, 01:55 PM #9spo0kFirehouse.com Guest
Columbus Ohio installed an 800mhz trunked system and allowed local departments (including ours) to pay to join in. This system has been up and running for a few years now (somewhere between 3-5) and we have had no major problems whatsoever. It's very easy to use, and has some very convienient features (private call, car to car, etc) and a powerful backup system in the event that the computer system goes down, which is a drill we practice yearly.
To my knowledge we use a Motorola Type II system..
FF. Mike Burnes
Whitehall Fire Division
06-16-2001, 05:27 PM #10Dalmatian90Firehouse.com Guest
-- Daily Radio Checks are no use if the repeater failed after the check...or the radio failed after the check...or a different repeater serves the fire location than your station.
-- The way I'm reading the "Emergency Evacuation" signal part is the Dispatch was hearing the fireground & trapped firefighters, and as a last resort was trying to trip the emergency alert on the radios to get their attention -- but no one on scene was receiving either Dispatch or other units including those trapped. That's why they weren't using air horns.
06-16-2001, 11:34 PM #11firedude3815Firehouse.com Guest
We switched from low band to 800mhz a few years ago. Our county in its infinite wisdom decided to skimp on towers and repeaters. They went with the low bid and we are now paying the price. There have been 2 new towers constructed and numerous repeaters set up since the initial bid.
How do the radios work? Well, the batteries die on the portables faster than we can charge them and with very little warning (no battery meter like a cell phone). Yes we've been using battery conditioners. You can be talking on a portable and then just a few moments later absolutely nothing! More than one guy has wanted to throw his portable into the street. The size of the portable could probably qualify it for a deadly weapon if used improperly The mobile radios make a loud squelching noise when the radio is cold. We get over 190" of snow a year! Apparently the radio manufacturers thought they were visiting Florida.
What are the good points? More channels and the ability to communicate across the county on a portable. We now have 9 fireground channels and a departmental operations channel. Before this system we couldn't reach dispatch on a portable.
Bad points? Radios are difficult to use if not trained properly. Not user friendly in a hazardous environment. Small buttons make it difficult to change channels. You have to wait for the beep before you can talk. That's assuming you can hear it! Your message may not have been transmitted. Now we do have the ability to use a conventional channel for interior ops but it doesn't reach dispatch.
So as you can see, I haven't been sold on the benefits of the 800mhz system. However, in our situation the powers that be tried to save money. Well, if you buy crap you get crap If your thinking about an 800mhz system do your research and don't let politicians make your job anymore dangerous than it has to be. Stay safe out there!
06-16-2001, 11:48 PM #12Capt. LouFirehouse.com Guest
After reading the article on the radio "booster" not working due to a tripped breaker, the question that comes to mind is why use a repeater for fireground operations? You, on the fireground, are only talking to someone (command-operations-etc.) who is usually very close in geographic proximity. A repeater works great for talking back to dispatch or unit to unit across town, but when your only 500' away from each other, my experience is you don't need the repeater to do that. My experience has also been that the higher the frequency the better the penetration in and out of steel and concrete buildings.
Wouldn't it make more sense to dispatch, transmit unit to unit across town, and unit to HQ or dispatch via the repeater. And use the "talkaround" frequency for your fireground operations or a different frequency for fireground operations. The key word is "fireground". Most firegrounds are not very large, so unit to unit transmissions would work very well.
Most of the time it is procedures that need fixing not equipment. Remember, keep it simple.
06-17-2001, 08:52 PM #13SkipDCFD/PG34BFirehouse.com Guest
I have only recently gotten involved with 800MHz Radios Systems and must say that I am not yet impressed. As with many of the tools we use in the fire service, it appears that how you spec a project has a direct effect on how the final product works.
800Mhz systems were explained to me in very simple terms. Digital Trunked systems, such as those in use in Delaware and Washington, DC, are much like the digital telephones everyone carries with them these days. In order for those phones to work reliably, there has to be a large number of transmission and repeater sites around. If these systems were set up like our FD radio systems then nobody's cell phone would work well and we would all be ****ed.
Chicago, Ill briefly had a 800Mhz system, but returned to their old VHF system, after firefighter's trapped in a basement could not reach the alarm office to summon help. I think that the recent events in NYC, Delaware, and WDC have shown us that the system is no where near perfect and is a significant safety issue.
06-17-2001, 10:01 PM #14cgoldyFirehouse.com Guest
We have used the 800 Mhz radio system for a number of years with usually good sucess. If we are deep within a large structure like a hospital (especially in the basements) we have been unable to talk with dispatch. By going to talk around and relaying our traffic to one of the trucks outside, we have been able to maintain communication.
With regards to the incident which prompted this discussion: did the firefighters inside who were in danger activate their pass alarms? Did the safety officer on scene know what was going on? Does the Chief or scene commander have a cell phone as a backup for communications? Don't they have a evacuation signal like airhorns that is used along with portable radios?
It sounds like there is a need for planning contingencies when equipment problems occur.
Plan your work, work your plan.
06-18-2001, 11:22 PM #15PFDE4Firehouse.com Guest
We've had alot of problems with our 800mhz system.
They say they are working on a fix but its been over a year or two. 100+ letters have been written, or so I have been told. I heard the last meeting in which the radio problem was mentioned, that the people responsible were notified of the manslaughter laws and their liablilty
06-18-2001, 11:53 PM #16Scottie SchmidtFirehouse.com Guest
to my knowledge the horns were not blown nor did i hear that he emergancy buttons were hit.
Scottie Schmidt JR (junior fire fighter
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