Mister gccradioscience has caught us unprepared.
The work on the Deep Voice Project hasn't gone forward since that last posting by me.
But the project is alive and well and will go forward.
It's just that I have too much bamboo. I'll explain later.
That also means that in Canada we can do "part 15" on FM and get the same transmit range as AM can get in the US with the AM rules there...and that's with the elaborate set up of an outdoor 3 meter antenna, loading coil and digging up the ground to install long ground radials, which the majority of people don't have access to do. Not to mention much better fidelity, no electrical noise, and getting signal into places that AM won't go.
Mark
That also means that in Canada we can do "part 15" on FM and get the same transmit range as AM can get in the US with the AM rules there
Suggest that this concept/conclusion needs more research.
There can be a BIG difference in the usefulness of a given field intensity arriving at the antenna of an AM broadcast receiver compared to an FM broadcast receiver.
For example, an AM transmitter meeting Part 15.219 might produce a field of ~ 30 µV/m several meters above the earth at a horizontal distance of 1 mile, over terrain of average earth conductivity.
That field at that distance is many times greater than can be generated by the unlicensed VHF FM systems permitted either by the US or Canada.
Other factors here are the typical ambient r-f noise levels present at the receive site, the sensitivities of those receivers, and their abllity to reject co- and adjacent-channel interference.
It would be a rare case where a legally operating, unlicensed FM setup would equal the useful coverage area of a legally operating AM setup when both met their respective maximum limits -- whether such were located in the US or Canada.
Building on Rich(F's) explanation about Part 15 AM having a significantly better coverage area than a Part 15 FM station, I have arrived upon an idea for a Poor Man's SCA which can be achieved on the AM band.
The acronym "SCA" refers to "Sub-Carrier Authority," which allows transmission of an entirely ADDITIONAL program on a single main carrier, allowing two or more programs that do not interfere with each other.
My Poor Man's Method shall have the acronym "DCA" which stands for "Dual Carrier Authority. The method will carry two monaural programs at the same time over a single AM carrier and requires an AM Stereo transmitter.
Mono Program # 1 will be sent on the Left Channel, and Mono Program # 2 shall be sent on the Right Channel.
Listeners, using stereo AM radios, will be instructed to choose ONLY the left or ONLY the right channel for listening.
Station breaks can be sent over both channels at the same time giving instructions for SEPARATING the two programs listeners will hear simultaneously if they don't know how to separate the channels.
This will revive AM stereo radios and transmitters and allow us to broadcast left wing and right wing programs at the same time.
In my Will I'm leaving the intellectual idea to the ALPB.
Mark's statement is entirely true in Canada. The BETS rules here for AM broadcasting do not allow 100mw input into the final stage of a transmitter - rather, they specify a field strength only (250uv/m at 30 meters). RSS210, which specifically disallows broadcasting, does have that provision, and that's what all AM transmitters here are certified under.
Line of sight range for a certified (under Canadian rules, both BETS and RSS210) FM transmitter is about 1km WITH QUIETING - and that's proven in the field by me. While it's entirely possible for a 100mw transmitter to get more range than that, as Mark points out, you need to do a lot more work (such as getting a good ground). I was able to get a consistent range of around a mile with a Rangemaster and Inovonics 222, but there was plenty of static at the outer limits - the static free range was more like 1/4 to 1/2 mile.
Overall, I've found by real world experience that in Canada, BETS FM is superior.
ArtisanRadio posted: The BETS rules here... specify a field strength only (250uv/m at 30 meters). ... While it's entirely possible for a 100mw transmitter to get more range than that, as Mark points out, you need to do a lot more work (such as getting a good ground). I was able to get a consistent range of around a mile with a Rangemaster and Inovonics 222, but there was plenty of static at the outer limits - the static free range was more like 1/4 to 1/2 mile.
Thanks for the clarification, AR. I thought Canada's rules for unlicensed AM essentially were the same as FCC §15.219.
Maybe I'm not understanding your post, but if the legal groundwave field intensity for MW AM transmit systems under BETS is 250 µV/m at a horizontal radius of 30 meters, then except for modulation capability, why would the manufacturer of that transmitter make any difference?
If all BETS-certified AM transmitters exactly met the field intensity limit at 30 meters, wouldn't they all have the same range (other things equal)?
It is also unclear how a BETS-certified AM transmitter just meeting its field intensity limit at 30 meters could have a static-free range of up to 1/2 mile. Its inverse distance (perfect ground plane) field at 1/2 mile would be 30m/805m x 250 µV/m = 9.3 µV/m. Wouldn't such a low value of field intensity be far below the ambient r-f noise level in the MW AM broadcast band for receive locations outside of a screen room?
You misunderstood.
ALL IC certified AM transmitters are certified under RSS210 (which for AM is pretty much identical to Part 15). If you follow the rules, then you are not allowed to broadcast with these (it's specifically not allowed) - there are other applications, such as Talking Signs, real estate, etc. that they are supposed to be used for (as well as experimentation). BETS, which contain the rules for broadcasting, does not have the 100mw provision on AM - the BETS rules for FM are essentially identical to those of RSS210.
There is no BETS certification. If you are investigated by Industry Canada, you just have to prove compliance with the rules. You can do that easily for FM if you have an RSS210 certified transmitter - AM is another matter, because, as previously discussed, the rules between RSS210 and BETS are different.
Even if you do use an RSS210 transmitter for AM broadcasting (not strictly legal), there are still advantages of FM (in Canada, where we're allowed 4 times the field strength) over AM. My point was that you get much greater signal quality with FM - even at a line of sight range of 1km, you're getting quieting at the fringes. With AM, static gets introduced (at least in a legal installation) much earlier - with my experiences in experimenting with a Rangemaster and Inovonics 222, it crept in somewhere between 1/4 to 1/2 mile (and usually at the lower end of that range). Yes, you can hear an AM station further (in my experiences, up to about a mile), and you might even want to listen to it, but there's lots of static and other noise.
Thanks for your latest comments on this, AR.
If I understand your posts correctly now, it appears that unlicensed operators using the AM broadcast band in Canada with programming intended for reception by specified audiences such as from talking signs and real estate properties legally are entitled to use transmit systems certified under RSS210, and which are comparable to FCC §15.219.
But unlicensed AM band operators in Canada legally wanting to "broadcast" to the general public must not exceed the 250 µV/m groundwave field intensity limit at a 30 meter radius permitted by BETS -- which (of course) could have a greatly limited range compared to RSS210.
If true, might it appear that the Canadian rules are oppositely skewed for those intended applications?
Rich, you now have it.
I'm not sure what the intention is for AM - you certainly won't get much range with a signal at 250uv/m at 30 meters.
Anyway, that's why, if you're concerned about Industry Canada and/or the CRTC knocking on your door, you're better off using FM in Canada. I haven't heard of anyone getting into trouble for using an RSS210 certified AM transmitter for broadcasting - that could be because there are plenty of open frequencies on it, or few care about it, or perhaps they just quietly are shut down.