The C.Crane is running at -45dbm (Per another site). And I've yet to find out the nanowatts of the Whole House Transmitter 3.0. Maybe we'll all find out soon enough.
I would have tested the output if I had the equipment lying around. I don't. I have to go by the certification. I looked at field strength meters and I'm not sure it's practical to have one right now because they're not cheap. Should we take the certification at face value? I don't think that anyone would exepct someone who drops $125 on a transmitter would drop $2000 on a field strength meter just to do a one-time test.
The reason all this started was two reasons: 1. I noticed that different part 15 transmitters had differences in range proving that some may NOT be3 putting out the full allowed power of a legal part 15 station. Then there was the question of Frankinmooth, Michigan in which there is a Christmas town and the transmitter they used is a part 15 transmitter and can certainly be heard for more than 150-200 feet. Light O Rama folks also use these transmitters and I've heard varied range reports from 75 Feet to ¼ mile on a good car Radio. Then the subject which questions rather or not the SainSonic AX-05B is a gray area or total black market FM Transmitter? Field test would certainly bust some myths and maybe stop part 15 stations from being harassed by bullies who don't like hobbyists on FM and want us to only play on AM. Now we may have a possible chance for change if the FCC expands the FM band down to either 68-107.9 or 76-197.9 Mhz. I know as soon as 87.9 Mhz is legal guess where you'll find me? It won't be 96.3 Mhz anymore that is for sure. I'll rest assured no matter what time of day it is I won't jam a station even on a temperature inversion.
... I'd like to see what the -------- puts out as far as field strength. ...
PLEASE NOTE that ALL FM transmit systems exactly meeting FCC §15.239 are limited to a field strength of 250 µV/m for a path length of 3 meters in all directions from the transmit antenna -- regardless of the output power rating/setting of the transmitter, and the transmit antenna it uses.
Other things equal, the field strength from such systems for a path length of 3 meters is unaffected by weather conditions.
Over time the performance of a certified transmitter is likely to vary, whether because of power-line fluctuations or weather or whatever. Of course the field reading at 3-meters would also vary, but this equipment does not exist in a static vacuum where changes never occur.
All things not always being equal.
...Of course the field reading at 3-meters would also vary, ...
It would not vary, as long as the r-f power and operating frequency applied to the feedpoint of that fixed antenna system (as installed) was constant.
Here is what I observe with regard to FM range and the weather. There is definitely some sort of relationship.
My range is the smallest when it is hot and sunny, generally in the middle of the day. Currently, amidst multiple obstructions (3 story townhouses, storefronts, etc.), I generally get a range around 250 meters. However, during cool temperatures, generally early in the morning or around sunset (although during a cool day I observe the same phenomenon in the middle of the day), my range goes up significantly, and it can be as much as 50-100 meters more. That's a change of 20-40%, and the only thing that's different is the weather. My transmitter is indoors, so the outdoor temperature is not affecting it at all.
I wonder how, if as Rich says, there is no relationship between weather and field strength along a signal path, one explains that?
My theory is that there are more particulates (i.e., smog) on hot, hazy days, and they are attenuating my tiny signal, reducing the field strength much as larger obstructions would. I notice the same effect when it rains or snows (my range goes even lower).
If there are any better theories out there, I'd really like to hear them, as I admit I'm grasping at straws here.
This is a comment on theLegacy's post regarding the transmitter that got 5 miles range.
I really don't like to say that something is impossible, but it is highly highly (highly) unlikely that a legal Part 15 FM signal could be heard at that kind of distance.
At 1000 feet, the field strength of that legal signal would be 2.5uv/m, and that's about the limit for any car radio or high end tuner with a sensitivity of under 1uv. It might be possible to increase that range further with an outdoor directional receiving antenna pointed at the transmitting antenna, line of sight, but that's certainly not going to be the normal listening post for most people, and I highly doubt that was the situation here.
If, as you say, the case was taken to court and the guy got off, it probably wasn't due to his operating the transmitter within legal field strength limits.
... My range is the smallest when it is hot and sunny, generally in the middle of the day. ... I wonder how, if as Rich says, there is no relationship between weather and field strength along a signal path, one explains that? ...
Such differences do exist for "long" propagation paths, but are negligible for VHF+ path lengths of three meters or so from the transmit antenna.
That 3-meter distance from the transmit antenna is used by the FCC to report the field strengths shown in most of the NOUOs they issue for non-compliance with §15.239.
Mr Rich is not a part 15 station hobbyist, yet he hovers around commenting negatively about what actual hobbyists do.
He said: "It would not vary, as long as the r-f power and operating frequency applied to the feedpoint of that fixed antenna system (as installed) was constant."
Trouble with that remark is it ignores the substance of my earlier Post # 20.
...Trouble with that remark is it ignores the substance of my earlier Post # 20. ...
Mr Blare: kindly note that -
MY post #19 here was based on other things equal.
YOUR posts #20 and #25 here are not based on other things equal.
A little science 101 here. I have seen the distance of a part 15 Transmitter very and quite often it is affected by weather conditions. Even the level of fm hiss is affected by the amount of ultraviolet rays caused by the the Sun. If you notice on a continuous band receiver the higher you go in frequency the louder the hiss becomes. This is why a police scanner has a squelch on it. When solar flares occur or the solar flux is higher the hiss becomes louder. The Sun cycle is also going to affect how loud the hiss is The closer you are to the 11th year of the Sun cycle the louder the hiss will be come on the FM band. Test a part 15 Transmitter on the 11th year of the sunspot cycle then test again on the first year of the next sunspot cycle and you'll see exactly what I mean. Your Transmitter will seem to transmit further but in actuality the noise floor is lower and hence the receiver is able to hear it further. Nothing was changed to the Transmitter final just the conditions of the Earth and the Sun. Sunspot cycles can affect even your tablet. During high solar flares could cause electronics to do things that are unexpected. FM radio can also be affected by moisture in the air. If you had a waterproof part 15 Transmitter and you were to stick it in the shower and turn on the steam and you had a waterproof receiver you would find out that your Transmitter would actually go further it would follow the moisture in the air. I would actually like to see that experiment done. This is something I learned in science class in college around 1984 when I was studying radio. FM radio and even 2 meter ham radio can be affected by weather even at a power of 100mW. Okay here's another thing I learned at WOCR in OlivetOlivet Mi. The reason you have to constantly check your power output by checking the amperage and voltage is because the AC power does fluctuate. Now I know on part 15 FM we're talking Nano watts but keep in mind that the Whole House fm Transmitter 3.0 and the C crane Transmitters both have AC power adapters and could be affected a little bit by power fluctuation. Also theoretically all part 15 Transmitter are not alike. Yes 250 microvolts per meter @ 3 meters is the maximum allowed limit at this time by the FCC in the United States. But and here is the kicker that doesn't mean the Transmitter is actually at maximum value by law. If that were the case every Transmitter out there sold on store shelves what at least go 250 feet a good radio and we know this is not the case. Why sometimes we get reports that the Whole House fm Transmitter 2.0 and 3.0 have a coverage of anywhere between 250 feet to 900 foot range. Yes it isYes it is that somebody is Transmitter might be over the limit. Hence the reason and this is very important and a very valuable reason why we should have them tested. The most popular Transmitter of course right now are the Decade cm10, Decade MS-100 The Whole House FM Transmitter 3.0, The Sainsonic ax-05B? C.Crane FM2 and Ramsey FM transmitters along with MobileBlackBox. All of which have been talked about on Christmas light forums as well as part 15 fm forums. There has been a lot of speculation as to why some of them get out for a bit further and I suspect that not all of the certified transmitters actually put out the full legal field strength. I think some manufacturers got cold feet because it does cost them to test every single Transmitter shipped. Thus I'm sure that there is a go between level that they actually set it to. The manufacturers that have more precision equipment will actually put it closer to the full legal limit. But the ones that don't do not want to take a chance and set it probably less than 50% of the full legal limit. This is why one company may seem to transmit further then the other. The goal is to find the Transmitter that Transmitter at full capacity. Also it could prove if it is the case the ones that are suspected to transmit over the limit are actually illegal. I am sure that some of my theory here will be proven correct once these tests are are final.
I think the ccrane is actually under the limit because you can go further than 40-75 feet as claimed by manufacturer and if you read reviews more people get a lot less.
The Wholehouse 3 proabably operates at part 15 limit based on the test I did comparing the wholehouse 3 to the decade CM-10 which operates at BETS.
Mark
Mr. Rich said (recently): "YOUR posts #20 and #25 here are not based on other things equal."
Here's a fact.
Things can be equal in the actual existential world for only an instant.
Albert Einstein said, "Nothing is simultaneous."
In his "Being or Nothingness" Jean Paul Sartre said much the same thing.
I'm telling you those micro-miniature-tiny-values in the nano-Watt region dance around and such tiny numbers amount to very little even if multiplied a few times here or there.
I saw a good movie on HULU last night. Do you ever have fun?
I thought I'd throw this in.
Foliage attenuation.
I don't know - I seem to remember
that a radio path through miles of
trees would change when the leaves
fell off the trees, or when trees were
wet from rain or snow???
I'm saying this backwards, but you
guys know what I mean.
But it's been so long I don't know if
I'm right. VHF? UHF? Both?
I don't know.
Tropospheric bending, ducting, etc.,
that happens for sure.
Brooce