Do you get better high end sound with the Whole House FM transmitter than the Decade or is the high frequencies in audio both the same at close range? Im trying to figure if the Decade is 75 uS pre emphasis or 50 uS making highs a little muddy sounding.
Highs were the same in both transmitters. Not sure if the CM-10 is 50 or 75 uS but I can adjust at source to get it to sound right. Actually don't know about the MS-100 either. I listen in the car to get the sound to be like the other stations...the car has a good sound system and I can hear low and high very well. But the Wholehouse, even when I added more bass at the source the "bottom" wasn't there. It just sounded more "boomy". The decade's have sound closer to hi-fi. Doesn't mean the Wholehouse is bad, just means on a good sound system you can hear a difference.
Mark
In my truck I have a Pioneer Super Tuner and a typical Ford 31 inch vertical antenna with about 6 feet of feed-line. My wife's Honda Pilot has a factory radio with an in-glass antenna located in the driver's side rear window. The antenna is less than 31 inches and is bent into a horizontal as well as vertical. The results between the two is significant.
These are two separate notes about things in this thread...
What readily available antenna technology is available to give circular polarization to Part 15 FM transmitters?
Here's a do-it-yourself circular FM antenna, but the author advises not using it below 10 Watts:
https://web.archive.org/web/20011122220119/http://members.tripod.com/AMN92/cp_ant.htm
Other subject, I have noticed that the Wholehouse 2.0, which is certified, puts out a lot of spurious signals all over the dial, more or less depending on the frequency it's set for. At least this is noticable nearby the transmitter, I don't think that RF junk gets out very far, but I'll do an analysis.
I think its a little normal for a full powered part 15 compliant transmitter to put out a litle bleed to a distance of around 5-10 feet. However my Transmitter at part 15 level I didn't notice any bleed. I think the review of the Maxell P-13 didn't mention any bleed on the dial. But its interesting how this transmitter is certified and seems to have harmonic and spur issues. If I didn't own my transmitter already and say they were to have pulled it from the market the Decade MS-100 looks nice or I'd try and get a Ramsey already assembled. The C.Crane has the issues with the antenna connection so someone would have had to modify it for me to have a wire instead. Or I could have got the Scoche and modified it to run on AC. Again for part 15 its really limited as to the good transmitters out there. If I win the Whole House Transmitter 3.0 I'd like to compare it with the one I already own and see the difference in quality and harmonics. I'd take it to Canada next time I visit my friend and run a test up there at BETS level and compare it to the SainSonic's High output.
Carl and Others: As you may have guessed, the Circular Polarized Antenna has negative gain slightly over 3 dB. So you would need two harnessed together to achieve unity.
@post 19&21
I think a strict interpretation of the part 15 rules would mean less field strength in the vertical (V) plane for circular polarized (CP) signal than if just a V polarized signal was used. If the CP antenna were putting out 250uv/m@3m in the horizontal (H) plane and 250uv/m@3m in the V plane, then if the measuring antenna were held halfway between vertical and horizontal it would get sin(45 deg)250uv/m@3m + cos(45 deg)250uv/m@3m = 354uv/m@3m. So I think to be part 15 compliant with CP, the field strength in the H plane would need to be 177uv/m@3m and the field strength in the V plane would need to be 177uv/m@3m (sin(45 deg)177uv/m@3m + cos(45 deg)177uv/m@3m = 250uv/m@3m). CP would allow a 41% increase in total power output (TPO), but it would decrease the field strength in the vertical plane by 29%.
Changing the antenna on a certified part 15.239 compliant transmitter will void the certification. That does not make illegal to use however it does mean without measuring the field strength there is no way to know if it is compliant. A true CP antenna for the FM band is going to be big. It will probably have ½ of a wavelength of metal to radiate in the H plane and ½ of a wavelength of metal to radiate in the V plane. A big part of true CP is the H component and the V components are 90 degrees out of phase. The vertical antennas on some certified part 15 transmitters are small because they don’t need to be resonant to achieve the full legal field strength. Going out and buying a pre-made commercial FM CP antenna and attaching it to a part 15 transmitter would probably exceed the allowable field strength because the commercial antenna would be resonant/more efficient.
This is a very interesting topic. It took me some time to carefully read through every word.
Since the Decade MS100 transmitter and CP was mentioned, I think I should share my experiences.
As you know from other threads on this site, that my studio fed 8 Decade MS100 FM transmitters located in various large multi-family apartment buildings.
At some point during my visits here at www.part15.us I am going to publish a lot of true information about WXTZ, which will include photos of WXTZ's former broadcast buildings. Although I have added information to the Wikipedia article for WXTZ, someone is always removing and objecting to what is added for various reasons, including missing citations to prove the statement is true etc. Some things are hard to prove other than word of mouth speculation.
I want everyone to see why we chose the buildings that we chose, and although an outside view of each building may not reveal just how many apartments are inside each of them, it still gives everyone an idea of the possibilities.
The Decade MS100 transmitters come with a vertical telescopic antenna.
We did not do an actual CP antenna, instead, we attached a set top, VHF television "V" dipole antenna to the stock antenna of the MS100, which was fully collapsed. We did some math to get the dipole to match 87.9MHz, which was our operating frequency. Some owners of those transmitters either had both rods perfectly horizontal, or a variation in between fully horizontal or at equal angles to each other to both being almost vertical. Sort of how people would tune in a VHF years ago with a set top VHF television antenna to tune in a television station.
Hopefully, You have an idea of how those antennas were used.
Now, I'm not saying that adding that antenna did not void the certification, but it also did not make the unit perform illegally.
So, why did our group use VHF dipoles?
Mostly because most home stereo systems come with a "T" type ribbon wire antenna for FM and also, most out door FM reception antennas are Horizontal, not vertical.
We did do some tests on 4 of the original Decade MS100 transmitters.
In the beginning, WXTZ was on a single Ramsey FM100 transmitter inside my house.
A few interested people wanted to be a part of the station and asked if they could re-transmit my station at their house. We knew that was no way, they could receive WXTZ and re-transmit it from their house without transmitting over the source.
People I knew from college, where I talked a lot about my station, came up with ideas. That is where the Barix equipment was brought up and soon, WXTZ was on a private stream over the Internet.
Another issue that surfaced for us was co-channel interference on our channel at night, specially during the summer months. We played around with one MS100 while a frequency counter was close by and we found that one set of switch settings gave us 87.9MHZ dead on frequency! We tried that setting on another unit and it to went to 87.9MHz dead on frequency!
So, WXTZ became WXTZ 87.9 Norwich.
We also found another issue and that issue was, only one or two people were able to get the signal.
This is where having a lot of friends and public exposure brings about our next project.
We thought, what would happen if we start adding these transmitters in locations where the signal reaches more people. Why not? Outdoor drive in theaters had a large crowd parked in the parking lot that were all able to get the signal.
Instead of a large parking lot, we chose large apartment buildings loaded with families.
At some point, I will use Google Earth or perhaps another on-line map program to show an aerial view of each location and plot out the signal zone, sort of how the FCC data base shows a licensed stations 60dBu contour.
We did not use an FIM71 or whatever it's called, but we did use portable radios to get an idea how far the signal traveled outside the building.
One thing I've noticed about part15.us is that I can not upload and add an image to another person's topic without hosting it on another site and adding a link to it here in this post.
If I could, I'd add one photo to this post that shows one such building, that one of those transmitters was located in.
Without photos for comparison, my descriptions would be hard to follow or envision without knowing what we're referring to. But, there is not doubt in my mind that FM carries a lot further than most of you give it credit for.
Bruce.
It's not really "real world" testing unless you expect your listeners in the real world to go out in their cars and listen to your station. What I think would be even more useful is when you go out testing again you bring along some other radios -- maybe a boombox, a small handheld potrable, maybe a more decent portable (Like a Super Radio, Grundig, etc) and see what you get. Bring some crappy radios like the typical person is likely to have. Then find a place maybe 300-400 feet away where you can go INSIDE with your radio and see what you can hear. Then you have some valuable real world testing that would more closely replicate what a typical listener might be doing.
If you want to go by "car testing" there's a stoplight 8 miles from my station (yes, I have to go 8 miles to get to a stoplight! Told you.. small town..) where I can hear my Part 15 AM station. And hear it pretty well, too. So I could say 'in the real world Part 15 AM goes 8 miles". At least, if you're driving my Ford Escape. And you're at THAT stoplight. And you don't have a blinker on, as the electronic interference from the blinker blinking drown out the station. If you're in the Mustang, you can't hear it at the same spot. Nor in my Wife's Focus. But every one of these vehicles picks it up loud and clear at 7100 feet away (my usual testing parking lot).
As for audio testing you simply cannot determine your sound based on listening to it. I know that sounds idiotic, but it's true. Every car radio, stereo, portable radio, etc has it's own frequency response. First thing you learn when working with a band in a recording studio is don't do the final mix based on the studio monitors alone, either (even high end flat response megathousand dollar speakers) because quite simply no one is going to be listening to your recording on that system. What sounds kick ass on one system usually sounds very different on another. I can right now put in a CD that sounds completely killer with a ton of bass in my livingroom, which has nearly no bass in the Escape. Even though a different recording sounds great in both with plenty of bass. Why? Because in the house the bass response goes lower that in the Escape so it's audible in the house. But a properly eq'ed recording has plenty of bass in the house AND the Escape. AND the portable radio. And everyone has their own idea of what sounds "correct" which is also influenced by your hearing. There's a reason radios have tone controls on them. So those who prefer more bass or high end can adjust accordingly. If you REALLY want to set things close to "in the ballpark". Use an audio spectrum analyzer. There are several available for Apple and Android devices, some are even free. Run your source audio into that and see what you get, the shoot for something similar on the receive end. In this case you'd have to sample the audio from the headphone jack of a radio so you have a direct line and you will need to be careful not to overdrive, etc but the apps will help you. Assuming what you have coming out of your source (in the above case, your iPhone) is what you want it to be, then adjust your processing and EQ to match. But remember too that the sound you hear from your source is also colored by what you're listening to -- speakers, ear buds, etc. The WORST thing you can do is adjust your sound to sound good in a vehicle with the best sound system, unless of course you have all listeners listening in cars with good systems. When you adjust for the sound on a given system, you're adjusting it to sound good on THAT system, rather than the best compromise to make it sound decent on MOST receivers. Of course if you're setting up sound with a high end FM processor (Just installed a new Orban in a 100,000 watt FM) there are a lot of visual cues to help you get setup.
I hope I explained that with some sort of clarity. I don't always translate thought into typing very good 🙂 43 years now in commercial broadcasting, over 20 in pro recording studios. I've been down the road and back again in this stuff. Try working at a radio station as engineer when the owner wants it to sound good on HIS car radio. And he's driving a 1985 Toranado with a stock radio. LOL.
Anyway, I'll consider your myth busted when you report with a table radio from inside a house 500 feet away. And even then you'd really need a field strength test to know that the radio is indeed legal. Even if it's certified the operator still has the responsibility to be legal. If the FCC shows up and says you're way over on field strength, they're not gonna send a notice to the Wholehouse folks, they're gonna pin YOU. I don't have any experience with Wholehouse units, and I have no clue how close their tolerances are held, but I bet things vary quite a bit from unit to unit.
For a longer post on another day -- I am in favor of an FM license (or whatever) that would allow the same coverage as Part 15. AM. But I don't think this can be done with a change to the Part 15 FM rules, as then it would apply to all Part 15 intentional radiators, like in car sound systems (ipod to the car radio for example). It would need to be a new and separate service. Getting THAT past the NPRM process will be quite a battle. Remember, Part 15 was never originally intended to provide for neighborhood broadcasting. Back in the 30's the little transmitters were first put into use to facilitate playing those new fangled electric phonographs into radios that people already owned. Then they turned into toys/kits/experiments for kids to " play DJ" then they became a way to play your tapes into your FM car radio without buying a new in dash cassette deck. And so forth and so on. The FCC, to my knowledge never talks about the intention of broadcasting to the public. That's just something the enterprising folks figured out when they realized what they had. So in the Part 15 world you have no existing precedent for using it for public broadcasting.
And I can guarantee you the music rights groups keep a close tab on everything. The second it hits the FCC news that someone wants a new super low power, maybe 1500 foot range FM station for the actual purpose of broadcasting to the public, they're gonna be on you like flies on honey to get their $$ for music rights. And I don't actually know, but I bet very few on this board with a Part 15 station are paying for any music rights at all. But I discussed that at length in another post somehwere on here. And you can bet that any legal system actually meant specifically for public broadcasting is going to come with a nice bunch of rules and regulations. You may have to have EAS, you may have to demonstrate some financial considerations, you may have to offer programming to minorities. the legal work for all this to happen is going to be long. I don't want to discourage trying, but it will probably take 5-7 years minimum. Music people will want money. The NAB will try to stop you. Even if by some miracle some new class was passed, standards will have to be determined, manufacturers will have to decide to build and spend the money to certify transmitters, then ramp up to manufacture them. You'll probably need FM modulation monitors unless the transmitters are required to be built in such a way that they can't overmodulate. I'm not saying it can't all be done. But it won't happen fast. The FCC can't and won't simply one day be convinced and announce "As of January 1st next year, Part 15 FM can have blah blah blah field strength". It just doesn't work like that.
Damn, now it sounds like I may have to purchase a couple of these FM transmitters and do some field strength tests. I have the equipment, I've just never had the desire to mess around with Part 15 FM. At least it's fairly easy. You only have to measure 3 meters from the antenna to know if you're legal! Uff-da.
Tim in Bovey
The 150 foot myth came from HB. We here have proof that the Whole Hokuse FM transmitter 3.0 can go 800 feet. Imagine placing 8 of them in intervals far enough apart and receiving from the same source. You could use routers and relay the stream right on down. It could prove interesting. 800 feet x 8=6,400 feet. Far beyond a single 500 mW TX. Something the anti FMers will cry about for Decades (HOW FITTING the name Decade).
This was a real-world DISTANCE test. It's irrelevant if people listen in their cars or not. The fact is that I busted the 150-foot myth.
As for the rest of your post, all those points have been covered. Nobody's trying to get anything for free here.
A lot of reading in the last post but points well taken.
When I sit in the car to hear how I sound I listen to how the other stations sound and then try to tailor my station to sound the same keeping the EQ or tone controls on the car stereo untouched, as best as my ears can tell. I then try to do a little tweeking...slightly more bass since cheap radios or boomboxes can't reproduce it as well so on what the average person may be listening on will hear a little mellower sound.....try to take out some of the "tinny" sound you get on small cheap things so will be more pleasing to the ear. And I see how sounds on a small radio similar to the Eton wind up ones which have very "tinny" sound.(I can't really listen to those things!) Most sangeans have nice mellow tone even though they are small....they go out of their way to EQ them to sound better.
When I did my test that I posted, I also as mentioned I took the portable and walked around the neighbourhood( the Geneva World radio) and reported on that too.
Mark
I read your post and I agree with you on the part about the music industry is going to want their cut for public exhibition rights.
Lets be serious here, regardless of what you broadcast, most copyright claims, state "Public exhibition of this material is prohibited by law."
Or
"Any rebroadcast of this material is prohibited."
I do know that I had a subscription that covered me as a neighborhood entertainment company, to use copyrighted music as a public entertainment provider.
Kind of the same as a club DJ who goes around making money on their music collection. Truth be told, a lot of club DJs download their music as MP3s and pay nothing to the music labels in return, but they are supposed to compensate the labels those songs are distributed by.
That same legal agreement that covers legal club DJs, can cover a part 15 radio station, because a part 15 radio station is providing a public exhibition of that music, to a small audience.
That is how WXTZ covered the re-broadcast and public exhibition of copyrighted music.
Don't forget, WXTZ was not available on the Internet to the general public, therefore, it was not required to do what Internet radio stations have to do, to avoid copyright infringement. Now that I am looking at Internet Radio, I know, I have to get the correct coverage, or face copyright infringement issues.
As far as EAS goes, I think if a radio service that is below that of LPFM is ever allowed, I think it should not require an active EAS system. Otherwise, VLPFM would be nothing more than a lower powered version of LPFM. I think the requirement of EAS in VLPFM should be non mandatory. If a VLPFM wants to include it, so be it, but if it can not afford it, it should not be a requirement to install it.
Bruce.
timinbovey, no one is arguing that you can get 500 feet range to a table radio with a legal Part 15 station. What IS being disproved is the myth that a legal Part 15 signal can't go any further than 200 feet, as has been widely reported elsewhere, on ANY radio. Heck, on one Forum someone in the broadcasting industry (I assume, since it was a broadcasting forum) stated quite categorically that a legal Part 15 signal can't go more than 3 meters (!?). I think he got power mixed up with field strength, but nonetheless, this is the type of misinformation that is being floated around in the broadcasting industry - and these guys all sound very authoritative while they're being totally wrong.
As for your table radio, it is likely, based on what I've researched, that it would be lucky to receive a legal Part 15 signal at 200 feet. The very best I found could probably get it (with noise - 20db SNR) at about 300 feet or so, line of sight, and some may not be able to hear it across the room (a big room, admittedly). It's even worse if you want full quieting (46db SNR) - the range could vary from 10 feet to 100 feet.
I also think that it's unwise to assume anything regarding music licensing. Anyone who is serious about Part 15 broadcasting will have it if they're playing copyrighted material, both for over-the-air and streaming.
I do agree with you that perhaps the best way to approach getting an increase in Part 15 range is with a new class of unlicensed service, similar to that of BETS in Canada. And the fact that such a service is already in place here would go a long way, I believe, in validating claims regarding potential interference (i.e., the sky hasn't fallen in on licensed broadcasters in Canada even though BETS has existed for some time).
Also, this isn't the thread for copyrighted music.