What are the regs for running an LPAM? Is this what college stations running on the AM band are doing, basically, under 10w and adhering to part 15 rules to divert licensing?
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LPAM
- Thread starter ajhenderson
- Start date
> What are the regs for running an LPAM? Is this what college
> stations running on the AM band are doing, basically, under
> 10w and adhering to part 15 rules to divert licensing?
>
You should check out posts regarding this subject right here on "Community Radio" under the "National" header. That section is pretty much devoted to this.
> stations running on the AM band are doing, basically, under
> 10w and adhering to part 15 rules to divert licensing?
>
You should check out posts regarding this subject right here on "Community Radio" under the "National" header. That section is pretty much devoted to this.
Is LPAM real and practical?
Hopin' for some insight from you folks. 1st, are'nt the College Stations on AM "Carrier Current"? And how exactly does that differ from "normal" AM Broadcasting? How does carrier current compare to the transmitters that are used, for example, near large airports or major freeways used to transmit information?
(Here in Washington State, we have (paraphrased) "When the weather sucks, tune to 1590 for the latest road info)(and yes, those suckers work a lot here in rainy Puget Sound!)
I really appreciate the sharing of your knowledge.
> What are the regs for running an LPAM? Is this what college
> stations running on the AM band are doing, basically, under
> 10w and adhering to part 15 rules to divert licensing?
>
Hopin' for some insight from you folks. 1st, are'nt the College Stations on AM "Carrier Current"? And how exactly does that differ from "normal" AM Broadcasting? How does carrier current compare to the transmitters that are used, for example, near large airports or major freeways used to transmit information?
(Here in Washington State, we have (paraphrased) "When the weather sucks, tune to 1590 for the latest road info)(and yes, those suckers work a lot here in rainy Puget Sound!)
I really appreciate the sharing of your knowledge.
> What are the regs for running an LPAM? Is this what college
> stations running on the AM band are doing, basically, under
> 10w and adhering to part 15 rules to divert licensing?
>
T
Tom_
Guest
Re: LPAM FCC LINKS
Here are two FCC links...however, much more out there on the FCC site......
WARNING: Be careful of NON-FCC web sites that have inaccurate information that if used could result in fines. Especially be carefull that the web sites are not from foreign countries where power and other restrictions may not be as signficant as teh US.
http://www.fcc.gov/mb/audio/lowpwr.html#CARRIER
Scroll down to download pdf bulletin no 63:
http://www.fcc.gov/oet/info/documents/bulletins/#63
This is just a start...there are more links...
Here are two FCC links...however, much more out there on the FCC site......
WARNING: Be careful of NON-FCC web sites that have inaccurate information that if used could result in fines. Especially be carefull that the web sites are not from foreign countries where power and other restrictions may not be as signficant as teh US.
http://www.fcc.gov/mb/audio/lowpwr.html#CARRIER
Scroll down to download pdf bulletin no 63:
http://www.fcc.gov/oet/info/documents/bulletins/#63
This is just a start...there are more links...
T
Tom_
Guest
Re: Is LPAM real and practical?
> Hopin' for some insight from you folks. 1st, are'nt the
> College Stations on AM "Carrier Current"? And how exactly
> does that differ from "normal" AM Broadcasting? How does
> carrier current compare to the transmitters that are used,
> for example, near large airports or major freeways used to
> transmit information?
> (Here in Washington State, we have (paraphrased) "When the
> weather sucks, tune to 1590 for the latest road info)(and
> yes, those suckers work a lot here in rainy Puget Sound!)
>
> I really appreciate the sharing of your knowledge.
Interesting!
I do recall years ago hearing NOAA weather radio somewhere around 1600 or so...
However, AM 1590 is licensed to Seattle and 5kW DAN and probably has a fairly good coverage area with the transmitter on Bainbridge and the signal skipping across the salt water. Are you sure you have heard this info on AM 1590, or could it be 530 which is used in the Seattle metro area for airport and traffic info???? Maybe 1590 is indeed used outside 1590 KLFE's coverage area, however, with the transmitter on the island, the coverage area is relatively large and not necessarily easy to define compared to if it was on land w/ low conducitivity w/ the Quaternary glacial sediments here...
> Hopin' for some insight from you folks. 1st, are'nt the
> College Stations on AM "Carrier Current"? And how exactly
> does that differ from "normal" AM Broadcasting? How does
> carrier current compare to the transmitters that are used,
> for example, near large airports or major freeways used to
> transmit information?
> (Here in Washington State, we have (paraphrased) "When the
> weather sucks, tune to 1590 for the latest road info)(and
> yes, those suckers work a lot here in rainy Puget Sound!)
>
> I really appreciate the sharing of your knowledge.
Interesting!
I do recall years ago hearing NOAA weather radio somewhere around 1600 or so...
However, AM 1590 is licensed to Seattle and 5kW DAN and probably has a fairly good coverage area with the transmitter on Bainbridge and the signal skipping across the salt water. Are you sure you have heard this info on AM 1590, or could it be 530 which is used in the Seattle metro area for airport and traffic info???? Maybe 1590 is indeed used outside 1590 KLFE's coverage area, however, with the transmitter on the island, the coverage area is relatively large and not necessarily easy to define compared to if it was on land w/ low conducitivity w/ the Quaternary glacial sediments here...
Re: Is LPAM real and practical?
Carrier current stations try to couple the AM signal into the power lines.
Goes about as far as the first transformer in the system.
Then there are travelers information stations, which are limited in power and bandwidth but can use a real antenna (which is also limited to be relatively inefficient). They are customarily licensed to government entities, such as the department of highways, or --airports.
There are also travelers information stations that use a combination of an antenna and a "leaky" cable, which is a coaxial cab le installed along side a highway. The cable is manufactured so that the shield has holes in it, allowing some radiation.
Carrier current stations try to couple the AM signal into the power lines.
Goes about as far as the first transformer in the system.
Then there are travelers information stations, which are limited in power and bandwidth but can use a real antenna (which is also limited to be relatively inefficient). They are customarily licensed to government entities, such as the department of highways, or --airports.
There are also travelers information stations that use a combination of an antenna and a "leaky" cable, which is a coaxial cab le installed along side a highway. The cable is manufactured so that the shield has holes in it, allowing some radiation.
Re: Is LPAM real and practical?
> Hopin' for some insight from you folks. 1st, are'nt the
> College Stations on AM "Carrier Current"? And how exactly
> does that differ from "normal" AM Broadcasting? How does
> carrier current compare to the transmitters that are used,
> for example, near large airports or major freeways used to
> transmit information?
> (Here in Washington State, we have (paraphrased) "When the
> weather sucks, tune to 1590 for the latest road info)(and
> yes, those suckers work a lot here in rainy Puget Sound!)
>
> I really appreciate the sharing of your knowledge.
>
> > What are the regs for running an LPAM? Is this what
> college
> > stations running on the AM band are doing, basically,
> under
> > 10w and adhering to part 15 rules to divert licensing?
> >
>
Oldnewbie:
I think the answer to "is it real and practical" is..sometimes.
A lot depends on your location, the number of signals on the dial and many other factors. I've done LPAM twice, with 2 different results.
In the early 90s I put a carrier-current station on 1120 AM. This set-up used
an LPB 35-watt transmitter which in turn fed a coupler to the power line.
The station sounded great..under the power lines, but, as tpt mentions below,
there was a transformer about 30 yards away. The signal got as far as the transformer and basically stopped. Now they use "neutral-injection" to get around that. I ran it for about 4 years anyway before selling the LPB box to a
campground that wanted a small TIS-type station.
In 2003, I built a full-fledged Part-15. This one, with its antenna mounted on a pole, had a listenable range of 2-plus miles and broadcast on 1160 kHz. It had a small loyal group of listeners and attracted some advertisers. We're fixing to move, and this property has a contract for sale, so I recently signed off. I'll start it up again after we move.
During the hurricanes of '04, at one point, every commercial AM in our market was knocked off the air. I stayed on the air with Red Cross shelter announcements, weather updates and the like. I don't know if anyone heard it,
but at that point, there was only 1 other signal on AM coming in, and they were airing back-to-back preachers.
Most of the college AMs are carrier-current. They are legally a little less restricted with their wattage, although they are supposed to pretty much keep the signal on the campus.
Florida State University has a TIS on 530 with 10 watts that goes out for several miles. Must be legal, as its been on for over a decade..
Hope this helps..<P ID="signature">______________
Memories Radio..
www.live365.com/stations/alanmccall</P>
> Hopin' for some insight from you folks. 1st, are'nt the
> College Stations on AM "Carrier Current"? And how exactly
> does that differ from "normal" AM Broadcasting? How does
> carrier current compare to the transmitters that are used,
> for example, near large airports or major freeways used to
> transmit information?
> (Here in Washington State, we have (paraphrased) "When the
> weather sucks, tune to 1590 for the latest road info)(and
> yes, those suckers work a lot here in rainy Puget Sound!)
>
> I really appreciate the sharing of your knowledge.
>
> > What are the regs for running an LPAM? Is this what
> college
> > stations running on the AM band are doing, basically,
> under
> > 10w and adhering to part 15 rules to divert licensing?
> >
>
Oldnewbie:
I think the answer to "is it real and practical" is..sometimes.
A lot depends on your location, the number of signals on the dial and many other factors. I've done LPAM twice, with 2 different results.
In the early 90s I put a carrier-current station on 1120 AM. This set-up used
an LPB 35-watt transmitter which in turn fed a coupler to the power line.
The station sounded great..under the power lines, but, as tpt mentions below,
there was a transformer about 30 yards away. The signal got as far as the transformer and basically stopped. Now they use "neutral-injection" to get around that. I ran it for about 4 years anyway before selling the LPB box to a
campground that wanted a small TIS-type station.
In 2003, I built a full-fledged Part-15. This one, with its antenna mounted on a pole, had a listenable range of 2-plus miles and broadcast on 1160 kHz. It had a small loyal group of listeners and attracted some advertisers. We're fixing to move, and this property has a contract for sale, so I recently signed off. I'll start it up again after we move.
During the hurricanes of '04, at one point, every commercial AM in our market was knocked off the air. I stayed on the air with Red Cross shelter announcements, weather updates and the like. I don't know if anyone heard it,
but at that point, there was only 1 other signal on AM coming in, and they were airing back-to-back preachers.
Most of the college AMs are carrier-current. They are legally a little less restricted with their wattage, although they are supposed to pretty much keep the signal on the campus.
Florida State University has a TIS on 530 with 10 watts that goes out for several miles. Must be legal, as its been on for over a decade..
Hope this helps..<P ID="signature">______________
Memories Radio..
www.live365.com/stations/alanmccall</P>
T
Tom_
Guest
Re: GROUNDWAVE and SKYWAVE distances and DIAL position...
you wrote:
> Florida State University has a TIS on 530 with 10 watts that
> goes out for several miles. Must be legal, as its been on
> for over a decade..
Tom responds:
For that low on the dial it would go several miles.
Indeed, I posted the following question on the DX board with no response. I would appreciate any feedback:
"As you go up the AM dial for the same amount of power the groundwave gradually decreases while the skywave increases.
Is there an approximation of a formulae that calculates these relationships, while eliminating other variables such as ground conductivity, terrain, etc.?
I see that stations in the X band of 1600-1710 kHz are limited to 10kW daytime and 1kW nightime.
Is this limitation perhaps a result of the enhanced skywave and potential mightime interference in northern latitudes in winter on the X band, resulting in a 1kW nightime maximum?"
you wrote:
> Florida State University has a TIS on 530 with 10 watts that
> goes out for several miles. Must be legal, as its been on
> for over a decade..
Tom responds:
For that low on the dial it would go several miles.
Indeed, I posted the following question on the DX board with no response. I would appreciate any feedback:
"As you go up the AM dial for the same amount of power the groundwave gradually decreases while the skywave increases.
Is there an approximation of a formulae that calculates these relationships, while eliminating other variables such as ground conductivity, terrain, etc.?
I see that stations in the X band of 1600-1710 kHz are limited to 10kW daytime and 1kW nightime.
Is this limitation perhaps a result of the enhanced skywave and potential mightime interference in northern latitudes in winter on the X band, resulting in a 1kW nightime maximum?"
Re: GROUNDWAVE and SKYWAVE distances and DIAL position...
There's a TIS at the LAX airport on 530. I can get it using a Panasonic RQ-SW20 and a Select-A-Tenna about 1.5 miles south of El Cajon, 1.5 miles east of La Mesa. Reception is somewhat weak, but intelligible, but made difficult with adjacent-channel interference from 540.
> you wrote:
>
> > Florida State University has a TIS on 530 with 10 watts
> that
> > goes out for several miles. Must be legal, as its been on
> > for over a decade..
>
> Tom responds:
>
> For that low on the dial it would go several miles.
>
> Indeed, I posted the following question on the DX board with
> no response. I would appreciate any feedback:
>
> "As you go up the AM dial for the same amount of power the
> groundwave gradually decreases while the skywave increases.
>
> Is there an approximation of a formulae that calculates
> these relationships, while eliminating other variables such
> as ground conductivity, terrain, etc.?
>
> I see that stations in the X band of 1600-1710 kHz are
> limited to 10kW daytime and 1kW nightime.
>
> Is this limitation perhaps a result of the enhanced skywave
> and potential mightime interference in northern latitudes in
> winter on the X band, resulting in a 1kW nightime maximum?"
>
There's a TIS at the LAX airport on 530. I can get it using a Panasonic RQ-SW20 and a Select-A-Tenna about 1.5 miles south of El Cajon, 1.5 miles east of La Mesa. Reception is somewhat weak, but intelligible, but made difficult with adjacent-channel interference from 540.
> you wrote:
>
> > Florida State University has a TIS on 530 with 10 watts
> that
> > goes out for several miles. Must be legal, as its been on
> > for over a decade..
>
> Tom responds:
>
> For that low on the dial it would go several miles.
>
> Indeed, I posted the following question on the DX board with
> no response. I would appreciate any feedback:
>
> "As you go up the AM dial for the same amount of power the
> groundwave gradually decreases while the skywave increases.
>
> Is there an approximation of a formulae that calculates
> these relationships, while eliminating other variables such
> as ground conductivity, terrain, etc.?
>
> I see that stations in the X band of 1600-1710 kHz are
> limited to 10kW daytime and 1kW nightime.
>
> Is this limitation perhaps a result of the enhanced skywave
> and potential mightime interference in northern latitudes in
> winter on the X band, resulting in a 1kW nightime maximum?"
>
Re: GROUNDWAVE and SKYWAVE distances and DIAL position...
http://500kc.com/downloads/rn04-5.pdf
check that out. Nice chart showing ground wave propagation.
Apparently, the closer you get to the ideal frequency of 500 khz,
the better the ground wave.
article/proposal relates to a new ham band at 500khz, but lot's
of interesting & useful info..
fmnostatic
> you wrote:
>
> > Florida State University has a TIS on 530 with 10 watts
> that
> > goes out for several miles. Must be legal, as its been on
> > for over a decade..
>
> Tom responds:
>
> For that low on the dial it would go several miles.
>
> Indeed, I posted the following question on the DX board with
> no response. I would appreciate any feedback:
>
> "As you go up the AM dial for the same amount of power the
> groundwave gradually decreases while the skywave increases.
>
> Is there an approximation of a formulae that calculates
> these relationships, while eliminating other variables such
> as ground conductivity, terrain, etc.?
>
> I see that stations in the X band of 1600-1710 kHz are
> limited to 10kW daytime and 1kW nightime.
>
> Is this limitation perhaps a result of the enhanced skywave
> and potential mightime interference in northern latitudes in
> winter on the X band, resulting in a 1kW nightime maximum?"
>
http://500kc.com/downloads/rn04-5.pdf
check that out. Nice chart showing ground wave propagation.
Apparently, the closer you get to the ideal frequency of 500 khz,
the better the ground wave.
article/proposal relates to a new ham band at 500khz, but lot's
of interesting & useful info..
fmnostatic
> you wrote:
>
> > Florida State University has a TIS on 530 with 10 watts
> that
> > goes out for several miles. Must be legal, as its been on
> > for over a decade..
>
> Tom responds:
>
> For that low on the dial it would go several miles.
>
> Indeed, I posted the following question on the DX board with
> no response. I would appreciate any feedback:
>
> "As you go up the AM dial for the same amount of power the
> groundwave gradually decreases while the skywave increases.
>
> Is there an approximation of a formulae that calculates
> these relationships, while eliminating other variables such
> as ground conductivity, terrain, etc.?
>
> I see that stations in the X band of 1600-1710 kHz are
> limited to 10kW daytime and 1kW nightime.
>
> Is this limitation perhaps a result of the enhanced skywave
> and potential mightime interference in northern latitudes in
> winter on the X band, resulting in a 1kW nightime maximum?"
>
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