12-08-1999, 08:00 PM #1IRallthewayFirehouse.com Guest
I was wondering how many departments out there are using transmitters on a regular basis?
12-15-1999, 02:06 PM #2TIManFirehouse.com Guest
As a point of reference about 85 percent of the units we are selling are equipped with transmitters. That would put the number of units in the field with transmitters at over 400.
A number of the departments (at least 35 percent) using the units have permanent receiving/display equipment mounted in their incident command vehicles. Many of these departments also have recording equipment, and it is in the SOP to record all incidents where the units are used.
A number of those departments also are using the transmitters in training. Some have permanent receiving, display, and recording equipment set up at their training facilities.
In a number of incidents the transmitters have been used to provide firefighters with a remote view of a hazardous location. In one incident the unit was lowered on a rope into a coal storage silo to determine the level of heat.
The transmitters have a number of uses, especially when coupled with recording equipment. Today's technology will allow the signal to be transmitted up to a mile in line of sight situations, and up to 400 feet in standard residential construction.
Hope this helps.
Good Luck, Be Safe,
12-30-1999, 10:19 PM #3JBFireFirehouse.com Guest
FYI for ALL the sales People and persons wanting to purchase the transmitters. THEY DONT WORK!
I asked about and had a demo with two dealers and transmitters. BOTH of them told me, "I'll sell you the transmitter but it's not worth the money. Most people still want them though!"
After these remarks, I started to look at other demos and found that these dealers have big bucks invested in Radio Shack to make the transmissions clearer than my Dish. The particles in the smoke will deminish the transmission and the actual band that the FCC has allotted is not the best for the situation that is intended.
So if you want the transmitter...be sure to get the antenna with the flashing red bulb on the end and good luck.
12-31-1999, 12:05 AM #4FireOpticFirehouse.com Guest
Interesting comment on the transmitters.
There are several criteria which must be factored into transmitter performance such as:
- Frequency of transmission
- Power of transmitter
- Effective gain of transmitting antenna
- Effective gain of receiving antenna
- Conditions of the fireground
- and several others....
Let me cut through the technojargon. Bottom line is that if a vendor is supplying a transmitter and a rep is touting it as ineffective or useless, then I would submit that behavior as being tantamount to negligence and misrepresentation.
In contrast to JBFire's experience, I do know that there are several TIC vendors supplying transmitter/receiver combinations that work very well in a variety of conditions and those vendors have paid close attention to the criteria I mentioned above. I would submit that they have found an increase in transmitter performance when smoke is present!! There is a sound technical reason why that is, but let's ignore that for now....
Many, if not most TICs sold today include transmitters and there is certainly a lot of field usage which can be reported on. Who out there likes their transmitter and finds it meets their expectations?
Who out there has a transmitter that did not meet your expectations? What are the conditions of usage that leads to this dissatisfaction? Let's hear dialog from real users and assist the firefighting community at large to help create guideline for application and usage!!
President - ICC
01-06-2000, 03:46 PM #5cwernerFirehouse.com Guest
I will have to contradict JBFire's comments about thermal image transmitters not working. While his experience may not be positive, we have seen many good benefits to transmitters. We have used them in actual fire training scenarios and been able to critique activities by observing teams working inside. We have also been able to use it to train personnel on what it looks like inside as we have video taped those activities.
While I appreciate the exchange of information, it is best not to make blanket statements that may or may not be correct for the rest of the fire service.
For other references, pls make sure that you express what your experiences are and be specific.
01-07-2000, 03:37 PM #6dalittleFirehouse.com Guest
Greetings! I hope you've enjoyed your holiday.
In a previous post you mentioned that smoke actually increases transmitter performance. Is that actually right? How so?
I would have thought it would have no effect, or marginal, or insignificant at best.
That's real interesting to me - and probably to the readers too???
Enjoy - and I'll talk to you soon...
David - ISG.
01-07-2000, 09:36 PM #7IRallthewayFirehouse.com Guest
In my very little use of transmitters I would have to say that I would also like to know why tranmitters work better in smoke. Since they use a radio frequency that would mean radios must work better in smoke as well! The only things that I know of that will affect the way a transmitter performs is strength(50mhz etc.) or structure makeup(concrete, steel, and wood walls). Other than that I don't think anything affects it.
As always be safe!
01-07-2000, 10:13 PM #8cwernerFirehouse.com Guest
I have to agree, I have never seen where smoke had any effect on the transmission. The key was distance between the TIC and the receiver and the type of building that it was trying to penetrate.
01-07-2000, 10:24 PM #9S. CookFirehouse.com Guest
Ours works fine in heavy smoke, both channels.
We use our transmitter primarily for training. We're planning to get a small TV/VCR for the rigs. Waiting for the prices to drop a little more on the DWI cams that the law uses. That way we can video the whole response, the initial sizeup and then switch to the imager.
Cairns has a slick unit, but they say it won't work with our Bullard imager/transmitter setup.
01-11-2000, 04:04 PM #10SKauffmanFirehouse.com Guest
Our department purchased the transmitter knowing its use would be limited to training or high hazard operations. Determine if the transmitter has any value to your department and not if it will be used daily.
01-11-2000, 04:52 PM #11FireOpticFirehouse.com Guest
Besides lack of transmit power, the thing that most dramatically affects a good video transmission is a phenomena known as multi-path.
Multi-path is caused when the receiver receives the same exact signal from what appears to be two different sources, and is caused by reflections and delays in the transmission path. These reflections and delays in transmission can be caused by just about anything and a house or other building is ripe for multipath opportunities. Multi-path interference is observed as black streaks on the screen, an occasional jitter in the signal or can be as profound as two complete images on the screen at the same time. Complete snow on the screen is caused by lack of transmit power.
The effect smoke and steam can (repeat can) have on the reduction of multipath is by actually weakening the signal strength via absorption of the radio signal in the smoke and water vapor in the air, which effectively reduces the strength of not only the main signal, but more importantly, the reflected signals, thereby allowing the receiver to "listen" to only one signal. The 2.4 GHz frequency used is the same frequency as many microwave ovens and was chosen specifically for its absorption in water (this is what heats the food in the microwave oven). Water in the air (steam) would be a good thing in this case.
If you speak in a completely empty room, you hear echoes and a overall reverberation of the sound. When furniture, rug or anything else is put in the room, the echoes subside and the main part of the conversation is heard more clearly. This is the same thing that can happen when smoke and steam is in the air during video transmission.
Hope this helps.
President - ICC
[This message has been edited by FireOptic (edited January 11, 2000).]
01-12-2000, 12:15 AM #12dalittleFirehouse.com Guest
I never thought of it that way, but it does make sense doesn’t it. Water absorbs RF especially at 2.4GHz, and even more as Fz gets higher - therefore, potentially only the strongest (the main) signal gets out.
Multipath fading (or overdriving) can be thought of as two or more waves that, at their extremes either are perfectly in phase with each other, thereby overdriving the signal, or perfectly out of phase thereby completely canceling the signal.
Think of yourself at the beach observing two sets of waves that come in from different
directions. At times, when the waves meet each other, they get real high, then, just as you thought the you’re about to see the mother of all waves, it just fizzled out for no apparent reason - that’s probably a pretty good analogy for what Tom is talking about.
Or, if you’ve connected your stereo speakers one side with +-, then the other with -+, you
notice a distinct lack of bass - that’s because the signals are out of phase and cancel themselves. Connect both correctly is OK, or both backward is also OK. Just not correct on one side, then wrong on the other. They gotta work together!
All transmitters suffer to some extent from multipath effects.
By the way, just one more “word of wisdom.” I noticed an earlier post referencing transmitter power measured in MHz - (Mega-Hertz). That is a very common misconception that purchasers and evaluators make. And, sadly, I’ve heard salesmen talk about “super powerful 2.4 GHz systems, etc... etc...”. It is apparent that they are misinformed as well.
The frequency, in megahertz (million cycles per second) or gigahertz (billion cycles per
second) are merely “roads or freeways” that the transmitter uses to send data to a receiver. It is not strength or power of the transmitter.
The power of the transmitter is measured in WATTS (milliwatts is a fraction of a watt
1/1000.) Thermal imagers’ transmitters are measured in milliwatts because the FCC
limits our output AND, high output at high frequency is hazardous to your health. Also,
we must consider that sensitivity of the receiver has a lot to do with transmitter
performance, this factor is independent of power level (in milliwatts.)
In fire service, many departments now use 800 MHz hand-held radios.
Now, what’s the transmit power of these hand-held radios? anyone know???
And, why can you transmit for miles with these radios, yet our thermal imagers are only capable of getting the signal to the street? can you take a stab at this one?? Two
Lastly, Tom Clynne is a competitor of mine - he is also an infrared imaging expert. He is very knowledgeable. I may not always agree with him but I will always listen to him and respect his thoughts because he is credible. A non-rookie - been around the block a couple of times!!
Thanks again, hope this didn’t bore you.
David A. Little
Director, North American Opers.
ISG Thermal Systems USA, Inc.
01-12-2000, 12:30 AM #13S. CookFirehouse.com Guest
Two prominant reasons - I'll take a guess:
#1. more power required to operate the video transmitter to send video signal
#2. most of the available power is being used to run the imager itself.
01-13-2000, 11:16 PM #14TIManFirehouse.com Guest
I am very glad to see that such a wealth of information is being exchanged here. Both Mr. Little and Mr. Clynne have done an outstanding job. I hope we can keep this type of quality information exchange going. I would add the following comments :
A common misconception I have run across on numerous occasions is that a thermal imager and portable radio will have the same transmission capability. Hopefully the information here has made it clear that it is not the case. The frequencies and the resulting capabilities of them to penetrate materials are different. Signal strength is also an issue. You are also talking about a video signal versus a radio signal. You may also be talking about digital versus analog. The capabilities of the receiving antennas can also be significantly different. The Bottom Line : TO MANY DIFFERENCES, do not assume that if your radio transmission is getting out that your video transmission is also, likewise do not assume that if your radio transmission can not get out that your video signal can not get out as well. The best way to find out, TRY IT ! That means you need to evaluate the transmitters under a number of different conditions. Obviously it is much better to know which structures a unit will or will not transmit out of than it is to know it is transmitting an analog signal, at a frequency of 2.457 gigahertz, at a strength of 400 milliwatts, etc.
Technical information and the ability to understand it can be great because it can help you weed through a sales pitch when the salesmen is trying to baffle you with a bunch of technical jargon. Of course you can just as easily get lost in the numbers / data game and forget to do the obvious which is to actually look at what you are referring to in person. On paper a certain thermal imager may be a pound lighter than any of the others, but if you held them in your hand and used them, you would not feel any real difference because the lighter unit is poorly balanced.
Some of the data you use in your evaluation will have to come solely from the manufacturers because you have no means of conducting the actions necessary to gather the data yourself. The majority of this information is legitimate but whenever possible you should gather your own data and / or verify the data provided by the manufacturer. This is especially important when information is not specific. Example : the manufacturer lists a NETD value in the form of a single number. This value can be measured based on a number of variables including f stop, detector rate, and the temperature at which the measurement was taken. Once again you will need to get this additional information because NETD values measured under different circumstances should not be compared. The manufacturer may be giving you the best number which may have come from an unrealistic or non standard set of variable conditions. The bottom line : if you do not verify or clarify this info you will most likely have some useless data because you can not use it for comparisons.
Make sure you are comparing apples to apples and not apples to oranges. For example ; thermal imagers can be weighed in a number of configurations, base unit, with battery, with transmitter, with optional equipment, etc. You would need to make sure when you compare the weights they are for units in the same configuration. Also the base unit with out a battery would give the lowest number but that is not how you are going to use it so what good does it do you to look at the weight of a configuration you are not going to use. The bottom line : it does you no good to gather data and compare it if your are not comparing data on the same exact thing or you are looking at data for something you will not use.
There is a certain amount of technical expertise and data that is useful in comparing thermal imagers. Doing your homework in these cases is invaluable and will keep a salesman from burying you or baffling you with technical jargon. Just make sure you do not get lost in a sea of data and miss the obvious real world input that will be right in front of you during an evaluation.
You might be able to buy the best imager off of a paper evaluation, but you would really have your work cut out for you. No question the best case scenario is a combination of some scrutinized paper data and some good observations from a hands-on evaluation.
Good Luck, Be Safe,
PS : Mr. Little & Mr. Clynne, what do you guys think about the manufacturers getting together and providing a list of standardized data that has been collected under a standardized set of conditions ? An organization like NFPA or NIST could determine the data and criteria. It would make everyone’s life in the Fire Service, who are evaluating thermal imagers, much easier. Of course it would also take away a lot of the smoke & mirror stuff that is currently going on in the sales & marketing game.
[This message has been edited by TIMan (edited January 14, 2000).]
[This message has been edited by TIMan (edited January 14, 2000).]
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