800, 700 "Mega" hurts

Replies to This Discussion

Permalink Reply by Brian Arnold on April 2, 2008 at 9:24am

Batteries last one hour to 12 hours depending on how new they are and how many previous charges they have had. Little green light indicating full charge may or may not indicate a full charge and several other problems that I could go on about.....our radios are kinda like playing russian roulette if you are jammed up and need them. They may Fire or they may not. With recent events in a near miss situation here in okc, the voice amps, radios and batteries are coming under closer scrutiny. But of course you know all this, just thought I'd kick things off...We've got some pretty good personnel working on the issue and I hope it gets resolved soon.....

Permalink Reply by Jay Michael on April 11, 2008 at 6:03pm

We went to the 800 mHz in December of '07. We don't have as much voice amp problems if we don't talk directly into the mic with the amp. Place the mic on the other side of the face piece. Dependability is the biggest concern. The complete 800 mHz system has been out of service for a week tomorrow. We have been using the old VHF system. I can't speak to what the problem is but it has something to do with the repeaters.
One of the comments on these mentioned roulette, this is about the best description any one could give with digital 800 mHz. The real problem is lack of confidence we have in the system. Even if it gets repaired and is dependable, how long will it be before we really believe it?

Permalink Reply by Drew Smith on April 12, 2008 at 6:10pm

While our department and regional dispatch does not use an 800 system, the regional we adjoin on our west side does. While thier system is 10 years old, it was supposed to solve some issues. Well, it seems they solved most of the old issues and replaced them with a bunch of new issues. The "busy signal" is my favorite. While we don't want to talk over one another, sometimes it is hard to get airtime.

What really gets me going about all these 800 systems is that operations inside the fire building, an IDLH atmosphere, are conducted on the 800 system which is not a simplex, line of sight system as required by NFPA 1221. Setting the NFPA standard aside, with these 800 systems you could be on the otherside of a wall from help and trapped and unable to hit the tower miles away. With the simplex set up it's line of sight and provided your battery is not dead you'l probably be heard by someone. Coupled with the trunked issue is the digitial issue-it's all or nothing. With old fashioned, analog, simplex radios even a weak signal from a weak battery will get you something.

Permalink Reply by mike diener on April 26, 2008 at 8:53am

Hi just joined this group. just some background, I am a member of a rural volunteer department. we use an 800mhz digital system. All the radio's have programed repeater channels and 3 simplex (talkaround) channels. on the fire ground we will all move to a talkaround to free up repeaters. this eliminates busy signals, however there a re still down sides. firefighters can still key up over someone is the biggest problem,but this is not anything new . we had the same problem on vhf analog as well. the other big concern is digital either works or not, no middle ground. on analog you could still hear traffic even if not 100% clear. I must say that I fought against the new digital system .for the most part the 800 trunked system works better than I would have thought. I still think that digital is not always better, but we seem to have worked it into our routine effectively. with the proper use of the simplex channels for fire ground comms we can hear all traffic and be intouch even in IDLH atmospheres.

Permalink Reply by Mike Walker on April 26, 2008 at 9:21am

Thanks for contributing Mike,

What brand of radio are you all using?

Have you all ever experienced poor transmission capability in loud noise environments? Such as PASS device activation, close PPV, etc?

Permalink Reply by Jason Ryan on May 2, 2008 at 9:58am

I have to agree with Mike. I am in the adjoining county and use the same radio system. I would have to say digital has its good points and its bad points. Here lately it has been horrible. Almost everytime you key up you get the busy tone. On scenes is the most agrivating part of the busy tone. We still carry VHF radios in all are rigs and all members are encourged to carry there VHF radios due to the fact that the 800's dont work the best in the area. For example: The other day we had a semi accident I was at the firehouse running traffic for the sheriff's dept and the fire dept. are guys were running on a tactical channel on VHF and releaying to me, who was aprox 8 miles away at the staion and in turn was on the 800 system or phone, relaying the info due to A: the busy tone or B: poor quiality of transmission.

Permalink Reply by Mike Walker on May 2, 2008 at 10:27am

Thanks for your input Jason

Permalink Reply by Jason Ryan on May 21, 2008 at 10:51am

Once again the great digital 800 radios let us down!!! All i have to say is that goodness for VHF in the area I am in. We had back to back runs the other day . Both runs were almost in the same place. We parked all are equipment in the same place and everything. And well we had to depend on VHF. The Sad part is there is an 800 tower about 4 miles from the location we were located. Still no good. IF you go 800 keep your VHF for back ups!!! They are a life saver.

Permalink Reply by Mike Walker on May 21, 2008 at 8:26pm

Jason, are you in Orlando?

Permalink Reply by Jason Ryan on May 21, 2008 at 9:02pm

No. I am located in West Central Indiana

Permalink Reply by Mike Walker on May 21, 2008 at 9:09pm

I guess I could have looked at your profile and found that out but I just read an article today where Orlando is having the same problems.

Permalink Reply by Mike Puchol on August 10, 2008 at 5:05pm

I have been involved in the rollout of a state-wide digital TETRA system in the 400 MHz band (we will have some 30.000 radios in service by next year), and after six years, the issues the "old timers" found are still standing. We went from Motorola MX1000s to Sepura SRP1000s - here is a quick run-down on how they compare:

- Service life: MX1000 have lasted an average of 15 years in service. SRP1000s go to get fixed at least once every 1.5 years in average (yes, the . is not a typo).

- Battery life: Motorola batteries, although not perfect, had almost double what you could get on the new digital sets. Also, since the digital radios work essentially like mobile phones, depending on what area they are in, they are constantly registering with the network, wasting battery even faster (and uselessly).

- Coverage: strong debate over this one - no doubt 400MHz has better in-building penetration than 80MHz (what we used before), but in these scenarios attack crews work in direct mode, where they would get 5W out of the Motorola sets versus 3W from the digital radios (more on this later). Thus, in rural areas, digital is essentially dead without good repeater coverage, which in turn means wads of cash.

- Ease of use: we went from 52 repeaters plus five direct channels to 140 talkgroups, which divided the network into very small chunks of land, thus making it harder for crews from across the line to work with each other, requiring frequent talkgroup changes. The usability of the digital handsets is similar to that of a cellphone, but with a tiny push-to-talk that is impossible to use even with technical rescue gloves. Also, trying to change talkgroup or even go to direct mode while in PPE is a daunting task. The old MX1000 was simple: one knob to turn it on, hear the beep, select the channel on the rotary buttons (i.e. you could count clicks, know what channel you were on without even looking at the thing), and go.

Another issue we saw with the digital network was the ability of radios in scan mode to saturate the repeaters. As you may know, digital systems are capable of carrying more than one logical channel on every physical radio frequency. In TETRA's case, you get four channels (known as timeslots). Let's say a radio is set to scan talkgroups 101 to 105. The radio informs the network that it wishes to receive a warning when any of the talkgroups becomes busy. Say 101 becomes active, the network will tell the radio, and the radio will "tune" to the timeslot occupied by the conversation. If then talkgroup 103 becomes active, the network has no idea what the radio's scanning priorities are, so it also informs it that talkgroup 103 is active, and starts broadcasting the activity on the next free timeslots. We now have two used timeslots, but the radio is only listening to one of them. As more and more talkgroups become active, the repeater can get saturated. Bad architecture design? You bet - but it's a very hard to avoid problem unless you disable scan mode on your radios. You may want to check if something like this can happen on your systems.

In general terms, my biggest problem is not so much from dispatch up to the vehicles, but from the vehicles / IC to the firefighters. We demonstrated an analog to digital gateway early on into the system's deployment (something the "engineers" said "could not be done"), meaning the fireground could still use the old trusted analog radios, and these could be gateway'd into the digital network as needed. The firefighter doesn't need to send text messages, or his GPS location. However, GPS tracking of responding vehicles has been of clear life-saving use in a few forest fire incidents, where airdrops could be precisely targeted to crews in distress.

Every technology has its use, and in my (old and tired) view, analog simplicity cannot be replaced on the fireground, whereas digital technology can improve operations of the department up to the vehicle level. And it seems I ran out of comment s