800, 700 "Mega" hurts

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Permalink回复Brian ArnoldonApril 2, 2008 at 9:24am

电池持续一小时到12个小时，具体取决于他们的新闻以及他们以前的费用有多少。小绿灯表明全部充电可能会或可能不会表明我可以继续充分收费和其他几个问题.....如果你被抓住并需要他们，我们的收音机有点像俄罗斯轮盘赌。他们可能会开火或者他们可能不会。随着最近在OKC的近乎未命中局势的事件，语音放大器，无线电和电池仔细审查。但当然你知道这一切，只是以为我会把事情踢掉......我们有一些相当好的人员在这个问题上工作，我希望它很快得到解决......

Permalink回复Jay Michaelon2008年4月11日下午6:03

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.
关于这些轮盘赌的评论之一，这是关于最好的描述，任何人都可以提供数字800 MHz。真正的问题是我们在系统中缺乏信心。即使它得到修复并是可靠的，在我们真正相信之前，它也会多长时间？

Permalink回复Drew Smithon2008年4月12日在下午6:10

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.

真正让我走向所有这些800系统是，在800个系统上进行了火灾建筑物内部的操作，这不是NFPA 1221所需的800个系统，这是一个单独的Simplex，使用这800个系统，您可以从帮助和困境的墙上的其他系统上，无法击中塔数英里。随着Simplex设置它的视线，只要您的电池没有死亡，您可能会被某人听到。耦合与集群问题是数字问题 - 这是全部或全部。凭借旧的形式，模拟，单纯X无线电甚至来自弱电池的弱信号也会给您带来一些东西。

Permalink回复mike dieneron2008年4月26日在上午8:53

嗨刚加入这个小组。只是一些背景，我是农村志愿者部门的成员。我们使用800MHz数字系统。所有收音机都有已编程的中继频道和3个单纯形（TalkAround）频道。在火灾地面上，我们将全部搬到会谈程序释放中继者。这消除了忙碌的信号，但是在那里仍然是侧面。消防员仍然可以关注某人是最大的问题，但这并不是什么新鲜事。我们也对VHF模拟有同样的问题。另一个重要的问题是数字无论是数字还是没有，没有中间地。在模拟上，即使不是100％清晰，也可以听到流量。 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回复Mike WalkeronApril 26, 2008 at 9:21am

Thanks for contributing Mike,

你使用什么牌子的收音机?

您是否曾在嘈杂的噪音环境中经历过差的传输能力？如通过设备激活，关闭PPV等？

Permalink回复杰森瑞安onMay 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回复Mike WalkeronMay 2, 2008 at 10:27am

感谢您的输入杰森

Permalink回复杰森瑞安on2008年5月21日上午10:51

再一次，伟大的数字800无线电让我们失望！我所要说的就是我在该地区的vhf的善良。我们在前几天回来了。两次运行几乎都在同一个地方。我们停放所有的设备都是同一个地方和一切。而且我们不得不依赖VHF。悲伤的部分是距离我们所在地约4英里的800塔。仍然没有好处。如果你去了800岁，请留下你的vhf !!!他们是一个救生员。

Permalink回复Mike Walkeron2008年5月21日在晚上8:26

杰森，你在奥兰多吗？

Permalink回复杰森瑞安on2008年5月21日晚上9:02

不，我位于印第安纳州西部

Permalink回复Mike WalkeronMay 21, 2008 at 9:09pm

我想我可以看看你的个人资料，发现了，但我刚刚读了一篇奥兰多在那里有同样问题的文章。

Permalink回复Mike PucholonAugust 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