FM sterio to AM streo , can it be done?

[sparky_marky]

Hi Guys,
we have a LPFM 22w (KWPA 103.1) station which has a very limited range and over 60% of the service area is over water( its on a island in the PNW) FCC map:
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FL1033322.html
which leaves the majority of the south end of the island with no signal.
We do have a RF engineer and plan to move the Tx to the south of the service
area. However there will still be a large dead spot and we want to carry a feed from the FM and use some p15 AM tx in a small town.
How hard is to go am sterio, and can you repeat the am sterio signal once it's been broadcast thru a Rangemaster?
thanks for taking the time to answer

sparky_marky

 

[RadioMan203]

Re: FM stereo to AM stereo , can it be done?

If you have the folks to do an engineering study why not just apply for a directional FM antenna pattern? We had an FM that was directional when they own stations in Connecticut and Long Island and used a directional to keep the CT signal out of Long Island.

 

[sparky_marky]

There are a number of issues ,20 miles or more from the edge of the current service zone, lots of hills, town business want to advertize. So feeding from non-commercial LPFM with towns CRS + local programing with part15 tx would be legal. plus it takes time and more $$ to get FCC repeater approval & study ,etc. and your still non- commercial.

Anybody know how far or even about a Decade ms100s FM tx?
They claim "type approved" , they also make a mono unit,but why?
From their site...http://www.decade.ca/AboutRegulations.html
"MS-100 series are FCC part 15 certified (FCC ID: MCHMS-100) and do not require a license for their operation in USA."

thanks

 

[Black_Shire]

Chris Cuff [email protected] or [email protected] makes a C-QUAM AM Stereo Part 15 AM transmitter (you can see one here at http://www.geocities.com/amstereo2001/ , at the very bottom of the screen-page). I have one that I use to listen to CDs around the house and out in the yard, using a Sony SRF-AX15 AM Stereo/FM Stereo Walkman receiver. I ordered it from Audio Cubes www.audiocubes.com , which sell the Sony SRF-AX15 Walkman and the Sony SRF-A300 AM Stereo/FM Stereo "boom-box."

It isn't FCC-Certified, *but* the Part 15 AM rules do permit home-built transmitters (as his are--he builds them by hand).


-- Black Shire

Hi Guys,
we have a LPFM 22w (KWPA 103.1) station which has a very limited range and over 60% of the service area is over water( its on a island in the PNW) FCC map:
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FL1033322.html
which leaves the majority of the south end of the island with no signal.
We do have a RF engineer and plan to move the Tx to the south of the service
area. However there will still be a large dead spot and we want to carry a feed from the FM and use some p15 AM tx in a small town.
How hard is to go am sterio, and can you repeat the am sterio signal once it's been broadcast thru a Rangemaster?
thanks for taking the time to answer

sparky_marky

 

[sparky_marky]

We need to cover about a 1 x 5 mile strip,
and of course want to be legit. An FCC approval is
a must.That is just like 3 tx's available to use that are somewhat
user friendly, well documented ,tried & true.
The more tx's used more likely one may be disabled, after all its out
in the countryside ,you should see all the shot up road signs.

 

[Chuck]

Re: FM stereo to AM stereo , can it be done?

If you have the folks to do an engineering study why not just apply for a directional FM antenna pattern? We had an FM that was directional when they own stations in Connecticut and Long Island and used a directional to keep the CT signal out of Long Island.

LPFM's are not allowed directional antennas, per FCC rules.

 

[Black_Shire]

We need to cover about a 1 x 5 mile strip,
and of course want to be legit. An FCC approval is
a must.That is just like 3 tx's available to use that are somewhat
user friendly, well documented ,tried & true.
The more tx's used more likely one may be disabled, after all its out
in the countryside ,you should see all the shot up road signs.

Home-brewed Part 15 AM transmitters such as Chris Cuff's C-QUAM unit are legal as long as they have a combined antenna + antenna feed line (if any) + ground lead length no greater than 3 meters, put out no more than 100 milliwatts, and hold off-frequency emissions (harmonics) at least 20 dB below the level of the un-modulated carrier. Compliance with these parameters can be confirmed using test equipment available to broadcaters.

Another thought: Are there a lot of power lines in this 1 X 5 mile strip? If so, AM Carrier Current (which also works well in C-QUAM AM Stereo, as Chris Cuff has done this as well) could be a solution. The Part 15 rules for AM Carrier Current broadcasting (Part 15.221, if I recall correctly) specify field strength limits that favor using the lower AM frequencies for maximum signal coverage.


-- Black Shire

 

[w9wi]

Re: FM stereo to AM stereo , can it be done?

If you have the folks to do an engineering study why not just apply for a directional FM antenna pattern? We had an FM that was directional when they own stations in Connecticut and Long Island and used a directional to keep the CT signal out of Long Island.

Is it legal to use a DA on a LPFM?

 

[kc8gpd]

as can be seen below. the rules are pretty restrictive for a lpfm.

Sec. 73.816 Antennas.

(a) Permittees and licensees may employ nondirectional antennas with
horizontal only polarization, vertical only polarization, circular
polarization or elliptical polarization.

(b) Directional antennas will not be authorized and may not be utilized in
the LPFM service, except as provided in paragraph (c) of this section.

(c) Public safety and transportation permittees and licensees, eligible
pursuant to Sec. 73.853(a)(ii), may utilize directional antennas in connection
with the operation of a Travelers' Information Service (TIS) provided each
LPFM TIS station utilizes only a single antenna with standard pattern
characteristics that are predetermined by the manufacturer. In no event may
composite antennas (i.e., antennas that consist of multiple stacked and/or
phased discrete transmitting antennas) and/or transmitters be employed.

(d) LPFM TIS stations will be authorized as nondirectional stations. The use
of a directional antenna as provided for in paragraph (c) of this section
will not be considered in the determination of compliance with any
requirements of this part.s.



73.811 LPFM power and antenna height requirements.

(a) LP100 stations: (1) Maximum facilities. LP100 stations will be
authorized to operate with maximum facilities of 100 watts effective
radiated power (ERP) at 30 meters antenna height above average terrain
(HAAT). An LP100 station with a HAAT that exceeds 30 meters will not be
permitted to operate with an ERP greater than that which would result in a
60 dBu contour of 5.6 kilometers. In no event will an ERP less than one watt
be authorized. No facility will be authorized in excess of one watt ERP at
450 meters HAAT.

(2) Minimum facilities. LP100 stations may not operate with facilities less
than 50 watts ERP at 30 meters HAAT or the equivalent necessary to produce a
60 dBu contour that extends at least 4.7 kilometers.

(b) LP10 stations: (1) Maximum Facilities. LP10 stations will be authorized
to operate with maximum facilities of 10 watts ERP at 30 meters HAAT. An
LP10 station with a HAAT that exceeds 30 meters will not be permitted to
operate with an ERP greater than that which would result in a 60 dBu contour
of 3.2 kilometers. In no event will an ERP less than one watt be authorized.
No facility will be authorized in excess of one watt ERP at 100 meters HAAT.

(2) Minimum Facilities. LP10 stations may not operate with less than one
watt ERP.

Sec. 73.860 Cross-ownership.

(a) Except as provided in paragraph (b) of this section, no license for an
LPFM station shall be granted to any party if the grant of such
authorization will result in the same party holding an attributable interest
in any other non-LPFM broadcast station, including any FM translator or low
power television station, or any other media subject to our broadcast
ownership restrictions.

(b) A party with an attributable interest in a broadcast radio station must
divest such interest prior to the commencement of operations of an LPFM
station in which the party also holds an interest unless such party is a
college or university that can certify that the existing broadcast radio
station is not student run. This exception applies only to parties that;

(1) Are accredited educational institutions, and;

(2) Own attributable interest in non-student run broadcast stations;

(3) Apply for an authorization for an LPFM station that will be managed and
operated on a day-to-day basis by students of the accredited educational
institution; and

(4) Do not face competing applications for the LPFM authorization.

(c) No LPFM licensee may enter into an operating agreement of any type,
including a time brokerage or management agreement, with either a full power
broadcast station or another LPFM station.

 

[sparky_marky]

Don't know much about CC & regs.
One major problem here, too many trees, powers off and lines down
if the wind blows over 40mph. It was up to 5+days for
some folks power to be restored.
Also isn't there something about CC can only go to the first transformer
on the power pole? or that it looses strength at each tf?
I'll read up a bit on CC
thanks guys

 

[kc8gpd]

what you need to do is find another community group to setup a translator to repeat your signal on the other side of the island.

Your group and the group owning the translator can not be affilated with each other. they would do their own fundraising to run the translator and you would do your own fundraising to run the LPFM and i beleive the translator can be a higher power than the LPFM.

This is the only solution i can see and it has been done once before that i know of and was accepted by the fcc.

 

[Black_Shire]

Don't know much about CC & regs.
One major problem here, too many trees, powers off and lines down
if the wind blows over 40mph. It was up to 5+days for
some folks power to be restored.
Also isn't there something about CC can only go to the first transformer
on the power pole? or that it looses strength at each tf?
I'll read up a bit on CC
thanks guys

You're most welcome. Carrier Current will go past the transformers if you use neutral injection (injecting the RF into the AC neutral lead) instead of "hot" injection (injecting the RF into the AC "hot" lead). Radio Systems www.radiosystems.com and LPB www.lpbinc.com produce Part 15 AM Carrier Current transmitters and AC line couplers for coupling the AM signal into the AC ines. Here is a link to the FCC Part 15 AM rules (including the Carrier Current rules): www.fcc.gov/mb/audio/lowpwr.html

AM Carrier Current signals can be received not only on AC-powered radios that are plugged into the AC lines carrying the signal, but also on radios within 150' - 300' of the power lines. While Radio Systems' and LPB's AM Carrier Current systems are mono, Chris Cuff [email protected] or [email protected] has experience in adding C-QUAM AM Stereo to mono AM systems, which isn't terribly difficult.


-- Black Shire

 

[sparky_marky]

seems most/lots of people that used CC went to leaky coax, pt15 , or lp
and what about the 60 cycle hum? is that from
using the line and not the neutral ? or is it always there?

as always you guys pump me up thanks
sparky_marky

 

[Black_Shire]

seems most/lots of people that used CC went to leaky coax, pt15 , or lp
and what about the 60 cycle hum? is that from
using the line and not the neutral ? or is it always there?

as always you guys pump me up thanks
sparky_marky

The 60 Hz AC hum can be filtered out, and neutral-injection CC systems are less prone to having the hum. The modern CC systems (Radio Systems' is the most up-to-date) are designed to avoid the hum.


-- Black Shire