The 19Khz is the pilot tone – the sub-carrier is 38Khz so the
stereo
info is modulated round 38Khz meaning its bandwidth is 23Khz-53Khz.

  Stewart Finlay


--- In LPFM_Radio@..., Mark Robinson
<mark.robinson@p...> wrote:
> >     *From:* Yellowbeard <mailto:yellowbeard@o...>
> >     *Subject:* [LPFM] Software stereo encoder....
> >     Howdy folks,
> >     A friend of mine from the Netherlands ( Radio Rob -
> >     http://www.rob007.8m.com/ ) sent me the details of stereo
encoder
> >     software that is now available, two caveats though, it only
runs
> >     under windows XP with service pack one and a sound card that
can
> >     handle 192KHz sampling rate. I have downloaded it, it is
only 175Kb,
> >     but I do not like and will not have windows XP on my
machine. Anyone
> >     fancy downloading this and telling us all how it goes? It is
at
> >     http://www.heinecke.nl/
>
> Ross Levis wrote:
>  > That's interesting.  I wonder why a more common 96kHz soundcard
could
>  > not be used.  I believe the modulation never exceeds 75khz for
FM.
>  >
>  > Ross.
>
> Hi Ross
>
> This is an apples and pears thing.
>
> At least two different things are being measured in kHz here.
>
> First some sampling theory. Nyquist's Theorem states that the
maximum
> frequency that can get through a sampled system (ie a sound card)
is
> half the sampling frequency. So a sound card sampling at 192,000
samples
> per second is going to pass a maximum frequency of 96Khz. The
stereo
> information is carried on a 19kHz audio subcarrier, above most
people's
> hearing. In order for this to work, the program needs to generate
this
> subcarrier with considerably more accuracy than Nyquist's Theorem
> suggests, and this means a higher sampling rate.
>
> Once the multiplex stereo signal (consisting of the audio and the
stereo
> subcarrier) is produced by the coder, it is frequency modulated
onto the
> RF carrier. The frequency of the transmitter is changed according
to the
> voltage from the coder. This frequency change is called deviation,
and
> too much is a bad thing as you indicate. Too much deviation will
make
> your signal clobber other stations on nearby channels (making them
and
> the MED grumpy), and cause distortion in your listener's
receivers.
> Higher frequencies in the modulating signal (the audio with stereo
> subcarrier) do increase the deviation, but this component is more
or
> less constant because the subcarrier is the highest frequency
present,
> and it is of constant amplitude.
>
> To recap, a high sampling rate (192kHz) provides a more accurate
audio
> signal and is a good thing, while high deviation (>75kHz) can make
your
> audio distort and make you interfere with other stations which is
a bad
> thing.
>
> Some people are tempted to turn the deviation all the way up to
get a
> 'stronger' signal. This is a bit misguided, because it only gives
a
> louder signal. To assess how strong your FM signal is listen to
the
> noise behind it. A good signal is "fully quieting", you can't hear
any
> noise in the receiver apart from that in the original audio.
>
> regards
> Mark

>     *From:* Yellowbeard <mailto:yellowbeard@...>
>     *Subject:* [LPFM] Software stereo encoder....
>     Howdy folks,
>     A friend of mine from the Netherlands ( Radio Rob -
>     http://www.rob007.8m.com/ ) sent me the details of stereo encoder
>     software that is now available, two caveats though, it only runs
>     under windows XP with service pack one and a sound card that can
>     handle 192KHz sampling rate. I have downloaded it, it is only 175Kb,
>     but I do not like and will not have windows XP on my machine. Anyone
>     fancy downloading this and telling us all how it goes? It is at
>     http://www.heinecke.nl/

Ross Levis wrote:
  > That's interesting.  I wonder why a more common 96kHz soundcard could
  > not be used.  I believe the modulation never exceeds 75khz for FM.
  >
  > Ross.

Hi Ross

This is an apples and pears thing.

At least two different things are being measured in kHz here.

First some sampling theory. Nyquist's Theorem states that the maximum
frequency that can get through a sampled system (ie a sound card) is
half the sampling frequency. So a sound card sampling at 192,000 samples
per second is going to pass a maximum frequency of 96Khz. The stereo
information is carried on a 19kHz audio subcarrier, above most people's
hearing. In order for this to work, the program needs to generate this
subcarrier with considerably more accuracy than Nyquist's Theorem
suggests, and this means a higher sampling rate.

Once the multiplex stereo signal (consisting of the audio and the stereo
subcarrier) is produced by the coder, it is frequency modulated onto the
RF carrier. The frequency of the transmitter is changed according to the
voltage from the coder. This frequency change is called deviation, and
too much is a bad thing as you indicate. Too much deviation will make
your signal clobber other stations on nearby channels (making them and
the MED grumpy), and cause distortion in your listener's receivers.
Higher frequencies in the modulating signal (the audio with stereo
subcarrier) do increase the deviation, but this component is more or
less constant because the subcarrier is the highest frequency present,
and it is of constant amplitude.

To recap, a high sampling rate (192kHz) provides a more accurate audio
signal and is a good thing, while high deviation (>75kHz) can make your
audio distort and make you interfere with other stations which is a bad
thing.

Some people are tempted to turn the deviation all the way up to get a
'stronger' signal. This is a bit misguided, because it only gives a
louder signal. To assess how strong your FM signal is listen to the
noise behind it. A good signal is "fully quieting", you can't hear any
noise in the receiver apart from that in the original audio.

regards
Mark

----- Original Message -----

From: Ross Levis

To: LPFM_Radio@...

Sent: Thursday, February 10, 2005 8:42 AM

Subject: Re: [LPFM] Software stereo encoder....

That's interesting.  I wonder why a more common 96khz soundcard could not be used.  I believe the modulation never exceeds 75khz for FM.

 

Ross.

----- Original Message -----

From: Yellowbeard

To: LPFM_Radio@...

Sent: Thursday, February 10, 2005 1:00 PM

Subject: [LPFM] Software stereo encoder....

Howdy folks,

A friend of mine from the Netherlands ( Radio Rob - http://www.rob007.8m.com/ ) sent me the details of stereo encoder software that is now available, two caveats though, it only runs under windows XP with service pack one and a sound card that can handle 192KHz sampling rate. I have downloaded it, it is only 175Kb, but I do not like and will not have windows XP on my machine. Anyone fancy downloading this and telling us all how it goes? It is at http://www.heinecke.nl/ 

 

 

Visit Yellowbeard's gashy Website
http://homepage.eircom.net/~yellowbeard/

---------------------------------------------------------
LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio

----- Original Message -----

From: Yellowbeard

To: LPFM_Radio@...

Sent: Thursday, February 10, 2005 1:00 PM

Subject: [LPFM] Software stereo encoder....

Howdy folks,

A friend of mine from the Netherlands ( Radio Rob - http://www.rob007.8m.com/ ) sent me the details of stereo encoder software that is now available, two caveats though, it only runs under windows XP with service pack one and a sound card that can handle 192KHz sampling rate. I have downloaded it, it is only 175Kb, but I do not like and will not have windows XP on my machine. Anyone fancy downloading this and telling us all how it goes? It is at http://www.heinecke.nl/ 

 

 

Visit Yellowbeard's gashy Website
http://homepage.eircom.net/~yellowbeard/

----- Original Message -----

From: Mix FM

To: LPFM_Radio@...

Sent: Wednesday, February 09, 2005 10:51 PM

Subject: [LPFM] Which transmitter is better?

Okay, so we've thrashed the Veronica brand of transmitters here quite a bit.

But what do you think of NRG vs Broadcast Warehouse?

I'd be interested in any thoughts/opinions on this one.

Good on you!

You could have called it "The Milk Shed" - that would have been a good
name too :-)

Jochen

>>> piratefm@... 9/02/05 >>>

Hi
I have just joined the list and thought I had better say hello.

I have been building my transmitter, stereo coder and studio in my
spare time for the last five months. My main aim is to be able to
listen to some decent music while I am in my milking shed or out in
the tractor. We can only receive two radio stations here and they
both sound better when they are turned OFF.

My gear is NRG PRO 3 exciter, NRG PRO 3 stereo coder, Phonic microV
compressor/limiter, AEV 6 channel stereo broadcast mixer, various CD
players etc, old 586 computer loaded with MP3's and running WinAmp
(just).

I have just finished tesing the transmitter and automation system
and now just have to load another thousandish songs to the playlist.

I am transmitting on 88.1 a few miles out of Opunake, I have been
strugling to come up with a name for the station and I have finally
settled on "Pirate FM", yes I know we are not pirates and yes I know
it is not original but who cares, I like it and that's what counts.

My favourite bit of kit is my antenna - - it is homemade out of a
chunk of old fence wire and goes heaps better than the one that I
paid $100 for (they are rebuiding it for me - hope they get it the
right size this time).

Anyone know how to pick up the satelite feeds for Hauraki??

See ya
Adam
Pirate FM





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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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<<<< GWAVASIG >>>>

Hi
I have just joined the list and thought I had better say hello.

I have been building my transmitter, stereo coder and studio in my
spare time for the last five months. My main aim is to be able to
listen to some decent music while I am in my milking shed or out in
the tractor. We can only receive two radio stations here and they
both sound better when they are turned OFF.

My gear is NRG PRO 3 exciter, NRG PRO 3 stereo coder, Phonic microV
compressor/limiter, AEV 6 channel stereo broadcast mixer, various CD
players etc, old 586 computer loaded with MP3's and running WinAmp
(just).

I have just finished tesing the transmitter and automation system
and now just have to load another thousandish songs to the playlist.

I am transmitting on 88.1 a few miles out of Opunake, I have been
strugling to come up with a name for the station and I have finally
settled on "Pirate FM", yes I know we are not pirates and yes I know
it is not original but who cares, I like it and that's what counts.

My favourite bit of kit is my antenna - - it is homemade out of a
chunk of old fence wire and goes heaps better than the one that I
paid $100 for (they are rebuiding it for me - hope they get it the
right size this time).

Anyone know how to pick up the satelite feeds for Hauraki??

See ya
Adam
Pirate FM





---------------------------------------------------------
LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio

I am using a NRG and have found it to be very good in an operational sense.

As far as building it and mounting it, it ain't so grand. The actual
assembly is simple enough, but when you come to put it in a case you find
that you are going to have problems getting all of the LEDs on the front
panel, unless you run hook-up wires from the board to remotely mounted LEDs.
NRG seriously advise against doing this. Also the RF output is mounted
towards the front of the board and requires a short coax cable in side the
case to go to the rear of the case, pitty they didn't use a right angled SO
239 on the back edge of the board.

All-in-all NRG have produced a damn fine kit that performs well. Just a
pitty they didn't design the PCB a little better.
Would I buy another NRG transmitter? Yes, without hesitation.

Adam

>
> Okay, so we've thrashed the Veronica brand of transmitters here quite a
> bit.
>
> But what do you think of NRG vs Broadcast Warehouse?
>
> I'd be interested in any thoughts/opinions on this one.
>
>
>
>
>
> ---------------------------------------------------------
> LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
> Yahoo! Groups Links
>
>
>
>
>
>
>
>

Okay, so we've thrashed the Veronica brand of transmitters here quite a bit.

But what do you think of NRG vs Broadcast Warehouse?

I'd be interested in any thoughts/opinions on this one.

Hi
I have just joined the list and thought I had better say hello.

I have been building my transmitter, stereo coder and studio in my
spare time for the last five months. My main aim is to be able to
listen to some decent music while I am in my milking shed or out in
the tractor. We can only receive two radio stations here and they
both sound better when they are turned OFF.

My gear is NRG PRO 3 exciter, NRG PRO 3 stereo coder, Phonic microV
compressor/limiter, AEV 6 channel stereo broadcast mixer, various CD
players etc, old 586 computer loaded with MP3's and running WinAmp
(just).

I have just finished tesing the transmitter and automation system
and now just have to load another thousandish songs to the playlist.

I am transmitting on 88.1 a few miles out of Opunake, I have been
strugling to come up with a name for the station and I have finally
settled on "Pirate FM", yes I know we are not pirates and yes I know
it is not original but who cares, I like it and that's what counts.

My favourite bit of kit is my antenna - - it is homemade out of a
chunk of old fence wire and goes heaps better than the one that I
paid $100 for (they are rebuiding it for me - hope they get it the
right size this time).

Anyone know how to pick up the satelite feeds for Hauraki??

See ya
Adam
Pirate FM

----- Original Message -----

From: Jochen Siegenthaler

To: DuffyFamily@... ; LPFM_Radio@...

Sent: Tuesday, February 08, 2005 1:37 PM

Subject: Re: [LPFM] Fw: LPTV

Hi M.B.,

The only policy framework in place is for non-commercial community TV.
This gives you a free licence, subject to your complying with certain
regulations and requirements.

You have to apply via MCH for a licence, MCH award based on your
application meeting policy requirements, and on MED advising that a
frequency is available in your desired area.

TV is subject to some strict interference conditions that limit re-use
of TV channels around the country.

I forget where you are - tell me where and I'll be able to take a stab
at what channels are available in your area.

Also:
for very very very LPTV you can use a video sender, available from Dick
Smith electronics etc.
Be aware that, even with an outdoor broadcast antenna, your coverage
area would be limited to within 100m or so.
And then typically only to one side of your house, as all the receive
antennas are directional, and some will not be pointing to your
transmitter.

Note carefully that TV is a directional system (unlike radio). To
achieve a good population reach, you need your transmitter located in a
spot where the majority of viewers have their antennas pointed to.
ie: the major broadcast site in your area, or within 100m of it.

If you are really serious about TV, talk to me offline. I have contacts
that can advise on how to make a TV station run very cheaply, ie: for
less than $100,000 you can have a full playout facility. That's dirt
cheap.

Cheers, Jochen (BCL)

Hi M.B.,

The only policy framework in place is for non-commercial community TV.
This gives you a free licence, subject to your complying with certain
regulations and requirements.

You have to apply via MCH for a licence, MCH award based on your
application meeting policy requirements, and on MED advising that a
frequency is available in your desired area.

TV is subject to some strict interference conditions that limit re-use
of TV channels around the country.

I forget where you are - tell me where and I'll be able to take a stab
at what channels are available in your area.

Also:
for very very very LPTV you can use a video sender, available from Dick
Smith electronics etc.
Be aware that, even with an outdoor broadcast antenna, your coverage
area would be limited to within 100m or so.
And then typically only to one side of your house, as all the receive
antennas are directional, and some will not be pointing to your
transmitter.

Note carefully that TV is a directional system (unlike radio). To
achieve a good population reach, you need your transmitter located in a
spot where the majority of viewers have their antennas pointed to.
ie: the major broadcast site in your area, or within 100m of it.

If you are really serious about TV, talk to me offline. I have contacts
that can advise on how to make a TV station run very cheaply, ie: for
less than $100,000 you can have a full playout facility. That's dirt
cheap.

Cheers, Jochen (BCL)

>>> DuffyFamily@... 4/02/05 >>>

----- Original Message -----
From: M.B & J.D Duffy
To: LPFM_Radio@...
Sent: Tuesday, February 08, 2005 2:09 PM
Subject: LPTV


Hi Group, just a silly little toying with an idea ?

What is rsm's view towards low power television transmissions?

Thanks M.B. D
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<<<< GWAVASIG >>>>

Trust the visit showed you complied with all applicable rules and
regulations :-)

He insisted correctly - a folded dipole = 2.2dBi gain. See my previous
posts from this morning!
A dipole can offer up to 4dB gain if mounted on the side of a
conductive pole or building (which acts like a reflector)

Jochen


>>> DuffyFamily@... 4/02/05 >>>
Please disregard my previous message dah!

I had a visit from your average freindly R.I just last week and he
questioned my use of 1 watt. I protested my inocence ie lots of high
loss co-ax and a folded dipole he however insisted that even a folded
dipole gave between 2-3 dbi gain.

M.B D

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<<<< GWAVASIG >>>>

You can use dBi (gain over isotropic) or dBd (gain over a dipole)

A dipole has 2.2 dBi, or 0dBd

Remember the basics:

To quote something in dB is only correct when you are talking a
relative gain (or loss) of an antenna
To quote the absolute level, you have to use dBi or dBd - the gain has
to have a reference point.

ie: to say an antenna radiates 3dB is wrong.

I see this mistake make all the time in noise reports in the
newspapers, where eg the Western Springs speedway has to keep its noise
below 100 decibels - such a statement is meaningless. The correct term
would be 100dBA, or whatever they use to measure noise.

Jochen

>>> mixfm@... 8/02/05 >>>
Isn't the base unit on which antenna gains are measured is
an isotropic radiator?

A dipole does not radiate in an isotropic fashion but
instead a flattened version where the radiation is greater
along the horizontal (ie: azimuthal angle) than it is
vertically.

I'm sure Jochen or others in the know will correct me if I
am wrong.



On Tue, 8 Feb 2005, Ross Levis wrote:

>> So use a dipole (approx 3dB gain)
>
> I'm fairly sure a standard dipole was considered the base
unit for
> measuring antenna gain, and it was given a 0db gain
rating.  ie. All
> other antennas gain is based on the dipole.  I've always
based by
> calculations around this fact.  Maybe I'm wrong.
>
> Ross.



---------------------------------------------------------
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<<<< GWAVASIG >>>>

I blame my poor memory :-)

I've checked with the experts, a standard dipole has a nominal gain of
2.2dBi.
But the principles are the same.

I always forget the exact figures for dBi - mainly because in my
professional life I always deal with gains of between 6 and 10dBi on our
large antenna systems

I've just been looking at a real-world example:
Antenna gain 4.2dBi
Feeder loss 2.0dB
And that's for a stacked dipole array offset from the pole.

Cheers, Jochen

>>> brianislay@... 8/02/05 >>>
Er Jochen,
Since when has a dipole antenna had 3db gain?
I am assuming a 1/2 wave ant.
Cheers
Brian

---------------------------------
Do I?

OK, here's how it works.

First the golden rule: Everything in FM works
backwards.

Why?

Receive level dictaes radiated power which dictates
antenna gain which
dictates antenna height wihich dictates feeder loss
which dictates
transmitter size.
Roughly.

For LPFM, the radiated power has a permitted maximum
of 500mW e.i.r.p
(effective isotropic radiated power) which is -3dBW.
The maximum is set
by the GURL licence for LPFM.
You could radiate less, but what's the point?

So to achieve the maximum of 500mW out of the antenna,
you need to know
your antenna gain and your feeder loss. This will then
dictate your
maximum permitted transmitter power.

But for flee-power LPFM space, don't bust a boiler
trying to be too
accurate.

There's not much point in using anything other than a
dipole or a
j-pole antenna - extra antenna gain gives no benefit
in the LPFM space.
In the high power space, antenna gain is used to keep
transmitter
powers and electricity consumption down. Both have a
big impact on
operating costs, but for LPFM, transmitters are cheap
and operating
costs are peanuts.

So use a dipole (approx 3dB gain)  and some coax
cable.
J-poles are good if you want to ground the antenna to
provide extra
lightening protection - a good idea, as I know of some
Veronica
transmitters that used to die regularly on a dipole,
and were reliable
on a J-pole due to the better protection.

Max licence power of -3dBW less 3dB antenna gain means
you feed the
antenna with -6dBW of power. That's 0.3 watts into the
antenna connector
at the antenna.

Assume your coax has 6dB of signal loss because it is
nice and long, so
you get -6dBW + 6 = 0dBW to be fed into the end of the
antenna coax.

And guess what 0dBW equates to?

You got it .... 1 watt.

If your coax feeder loss is less than 6dB, you will
need to reduce your
transmitter power to stay within the regulations. This
has the added
benefit of reducing the hard work that the final
amplifier has to do,
and making it more reliable.

Cheers, Jochen

>>> mixfm@... 7/02/05 >>>

Yes, but when you take into account loss due to SWR
(which are affected

by a number of factors), loss through co-ax cable, the
fat pigeon that

roosts on your antenna, etc, it's not hard to take you
down to around
0.5 W.

Jochen usually replies to these types of emails.....

Michael Rowse wrote:
> Isn't 1 watt twice what you are allowed under the
rules of LPFM here
in NZ??
>
> I'm just checking because I'm about to buy a TX too
and 1 watt would
be
> great...much better than the 500mW that I thought we
had to have.
>
> */Jo Hodge <j.c.hodge.bro@...>/* wrote:
>
>     Joe Hodge Wanganui,
>     Music Memories FM 88.6, Wangani Community Based
Radio Staion for
>     Senior Citizens
>     We are a charitable natured organisation.
>
>     A big Hi to the LPFM group.
>
>     Does anyone out there have a Tx to sell.
Preferably NRG 1watt.
>     Hope to hear from somebody soon.
>
>     so36jo@... <mailto:so36jo@...>
>     phone:(06) 347 8143
>
>     Bye.
>
>
>
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Isn't the base unit on which antenna gains are measured is
an isotropic radiator?

A dipole does not radiate in an isotropic fashion but
instead a flattened version where the radiation is greater
along the horizontal (ie: azimuthal angle) than it is
vertically.

I'm sure Jochen or others in the know will correct me if I
am wrong.



On Tue, 8 Feb 2005, Ross Levis wrote:

>> So use a dipole (approx 3dB gain)
>
> I'm fairly sure a standard dipole was considered the base
unit for
> measuring antenna gain, and it was given a 0db gain
rating.  ie. All
> other antennas gain is based on the dipole.  I've always
based by
> calculations around this fact.  Maybe I'm wrong.
>
> Ross.

Er Jochen,
Since when has a dipole antenna had 3db gain?
I am assuming a 1/2 wave ant.
Cheers
Brian

---------------------------------
Do I?

OK, here's how it works.

First the golden rule: Everything in FM works
backwards.

Why?

Receive level dictaes radiated power which dictates
antenna gain which
dictates antenna height wihich dictates feeder loss
which dictates
transmitter size.
Roughly.

For LPFM, the radiated power has a permitted maximum
of 500mW e.i.r.p
(effective isotropic radiated power) which is -3dBW.
The maximum is set
by the GURL licence for LPFM.
You could radiate less, but what's the point?

So to achieve the maximum of 500mW out of the antenna,
you need to know
your antenna gain and your feeder loss. This will then
dictate your
maximum permitted transmitter power.

But for flee-power LPFM space, don't bust a boiler
trying to be too
accurate.

There's not much point in using anything other than a
dipole or a
j-pole antenna - extra antenna gain gives no benefit
in the LPFM space.
In the high power space, antenna gain is used to keep
transmitter
powers and electricity consumption down. Both have a
big impact on
operating costs, but for LPFM, transmitters are cheap
and operating
costs are peanuts.

So use a dipole (approx 3dB gain)  and some coax
cable.
J-poles are good if you want to ground the antenna to
provide extra
lightening protection - a good idea, as I know of some
Veronica
transmitters that used to die regularly on a dipole,
and were reliable
on a J-pole due to the better protection.

Max licence power of -3dBW less 3dB antenna gain means
you feed the
antenna with -6dBW of power. That's 0.3 watts into the
antenna connector
at the antenna.

Assume your coax has 6dB of signal loss because it is
nice and long, so
you get -6dBW + 6 = 0dBW to be fed into the end of the
antenna coax.

And guess what 0dBW equates to?

You got it .... 1 watt.

If your coax feeder loss is less than 6dB, you will
need to reduce your
transmitter power to stay within the regulations. This
has the added
benefit of reducing the hard work that the final
amplifier has to do,
and making it more reliable.

Cheers, Jochen

>>> mixfm@... 7/02/05 >>>

Yes, but when you take into account loss due to SWR
(which are affected

by a number of factors), loss through co-ax cable, the
fat pigeon that

roosts on your antenna, etc, it's not hard to take you
down to around
0.5 W.

Jochen usually replies to these types of emails.....

Michael Rowse wrote:
> Isn't 1 watt twice what you are allowed under the
rules of LPFM here
in NZ??
>
> I'm just checking because I'm about to buy a TX too
and 1 watt would
be
> great...much better than the 500mW that I thought we
had to have.
>
> */Jo Hodge <j.c.hodge.bro@...>/* wrote:
>
>     Joe Hodge Wanganui,
>     Music Memories FM 88.6, Wangani Community Based
Radio Staion for
>     Senior Citizens
>     We are a charitable natured organisation.
>
>     A big Hi to the LPFM group.
>
>     Does anyone out there have a Tx to sell.
Preferably NRG 1watt.
>     Hope to hear from somebody soon.
>
>     so36jo@... <mailto:so36jo@...>
>     phone:(06) 347 8143
>
>     Bye.
>
>
>
---------------------------------------------------------
>         LPFM Website:
http://au.groups.yahoo.com/group/LPFM_Radio
>
>
>
>
---------------------------------------------------------
>         LPFM Website:
http://au.groups.yahoo.com/group/LPFM_Radio
>
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>         Checked by AVG Anti-Virus.
>         Version: 7.0.300 / Virus Database: 265.8.5 -
Release Date:
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>
>
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Do I?

OK, here's how it works.

First the golden rule: Everything in FM works backwards.

Why?

Receive level dictaes radiated power which dictates antenna gain which
dictates antenna height wihich dictates feeder loss which dictates
transmitter size.
Roughly.

For LPFM, the radiated power has a permitted maximum of 500mW e.i.r.p
(effective isotropic radiated power) which is -3dBW. The maximum is set
by the GURL licence for LPFM.
You could radiate less, but what's the point?

So to achieve the maximum of 500mW out of the antenna, you need to know
your antenna gain and your feeder loss. This will then dictate your
maximum permitted transmitter power.

But for flee-power LPFM space, don't bust a boiler trying to be too
accurate.

There's not much point in using anything other than a dipole or a
j-pole antenna - extra antenna gain gives no benefit in the LPFM space.
In the high power space, antenna gain is used to keep transmitter
powers and electricity consumption down. Both have a big impact on
operating costs, but for LPFM, transmitters are cheap and operating
costs are peanuts.

So use a dipole (approx 3dB gain)  and some coax cable.
J-poles are good if you want to ground the antenna to provide extra
lightening protection - a good idea, as I know of some Veronica
transmitters that used to die regularly on a dipole, and were reliable
on a J-pole due to the better protection.

Max licence power of -3dBW less 3dB antenna gain means you feed the
antenna with -6dBW of power. That's 0.3 watts into the antenna connector
at the antenna.

Assume your coax has 6dB of signal loss because it is nice and long, so
you get -6dBW + 6 = 0dBW to be fed into the end of the antenna coax.

And guess what 0dBW equates to?

You got it .... 1 watt.

If your coax feeder loss is less than 6dB, you will need to reduce your
transmitter power to stay within the regulations. This has the added
benefit of reducing the hard work that the final amplifier has to do,
and making it more reliable.

Cheers, Jochen

>>> mixfm@... 7/02/05 >>>

Yes, but when you take into account loss due to SWR (which are affected

by a number of factors), loss through co-ax cable, the fat pigeon that

roosts on your antenna, etc, it's not hard to take you down to around
0.5 W.

Jochen usually replies to these types of emails.....

Michael Rowse wrote:
> Isn't 1 watt twice what you are allowed under the rules of LPFM here
in NZ??
>
> I'm just checking because I'm about to buy a TX too and 1 watt would
be
> great...much better than the 500mW that I thought we had to have.
>
> */Jo Hodge <j.c.hodge.bro@...>/* wrote:
>
>     Joe Hodge Wanganui,
>     Music Memories FM 88.6, Wangani Community Based Radio Staion for
>     Senior Citizens
>     We are a charitable natured organisation.
>
>     A big Hi to the LPFM group.
>
>     Does anyone out there have a Tx to sell.  Preferably NRG 1watt.
>     Hope to hear from somebody soon.
>
>     so36jo@... <mailto:so36jo@...>
>     phone:(06) 347 8143
>
>     Bye.
>
>
>         ---------------------------------------------------------
>         LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>
>
>         ---------------------------------------------------------
>         LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>         No virus found in this outgoing message.
>         Checked by AVG Anti-Virus.
>         Version: 7.0.300 / Virus Database: 265.8.5 - Release Date:
3/02/05
>
>
------------------------------------------------------------------------
> Do you Yahoo!?
> Yahoo! Search presents - Jib Jab's 'Second Term'
>
<http://us.rd.yahoo.com/evt=30648/*http://movies.yahoo.com/movies/feature/jibjab\
inaugural.html>

>
>
> ---------------------------------------------------------
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>
>
>
------------------------------------------------------------------------
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>



---------------------------------------------------------
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CAUTION : This email message and attachments are confidential and
may contain legally privileged information or copyright material. If you
have received this email in error, please advise the sender immediately
by return email and then delete both messages and any attachments.
If you are not the intended recipient you are notified that any use,
distribution, amendment, copying or any action taken or omitted to be
taken in reliance of this message or attachments is prohibited. We do
not accept liability in connection with computer virus, data corruption,
delay, interruption, unauthorised access or unauthorised amendment.
Views expressed in this email may not be those of originating organisation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

<<<< GWAVASIG >>>>

Yes, but when you take into account loss due to SWR (which are affected
by a number of factors), loss through co-ax cable, the fat pigeon that
roosts on your antenna, etc, it's not hard to take you down to around 0.5 W.

Jochen usually replies to these types of emails.....

Michael Rowse wrote:
> Isn't 1 watt twice what you are allowed under the rules of LPFM here in NZ??
>
> I'm just checking because I'm about to buy a TX too and 1 watt would be
> great...much better than the 500mW that I thought we had to have.
>
> */Jo Hodge <j.c.hodge.bro@...>/* wrote:
>
>     Joe Hodge Wanganui,
>     Music Memories FM 88.6, Wangani Community Based Radio Staion for
>     Senior Citizens
>     We are a charitable natured organisation.
>
>     A big Hi to the LPFM group.
>
>     Does anyone out there have a Tx to sell.  Preferably NRG 1watt.
>     Hope to hear from somebody soon.
>
>     so36jo@... <mailto:so36jo@...>
>     phone:(06) 347 8143
>
>     Bye.
>
>
>         ---------------------------------------------------------
>         LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>
>
>         ---------------------------------------------------------
>         LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>         No virus found in this outgoing message.
>         Checked by AVG Anti-Virus.
>         Version: 7.0.300 / Virus Database: 265.8.5 - Release Date: 3/02/05
>
> ------------------------------------------------------------------------
> Do you Yahoo!?
> Yahoo! Search presents - Jib Jab's 'Second Term'
>
<http://us.rd.yahoo.com/evt=30648/*http://movies.yahoo.com/movies/feature/jibjab\
inaugural.html>
>
>
> ---------------------------------------------------------
> LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>
> ------------------------------------------------------------------------
> *Yahoo! Groups Links*
>
>     * To visit your group on the web, go to:
>       http://au.groups.yahoo.com/group/LPFM_Radio/
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>       LPFM_Radio-unsubscribe@...
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>
>     * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
>       Service <http://au.docs.yahoo.com/info/terms/>.
>
>

Michael Rowse wrote:

> Isn't 1 watt twice what you are allowed under the rules of LPFM here in NZ??
>
> I'm just checking because I'm about to buy a TX too and 1 watt would be
> great...much better than the 500mW that I thought we had to have.

As I understand it, the 500mW is "radiated power" measured a certain
distance from the antenna, not transmitter power, so it depends on
what your antenna gain is, and how much signal is lost in the antenna
feeder cable.

I'm sure some of the others on the list will be able to give
a definitive answer.

Cheers, Chris

>
> */Jo Hodge <j.c.hodge.bro@...>/* wrote:
>
>     Joe Hodge Wanganui,
>     Music Memories FM 88.6, Wangani Community Based Radio Staion for
>     Senior Citizens
>     We are a charitable natured organisation.
>
>     A big Hi to the LPFM group.
>
>     Does anyone out there have a Tx to sell.  Preferably NRG 1watt.
>     Hope to hear from somebody soon.
>
>     so36jo@... <mailto:so36jo@...>
>     phone:(06) 347 8143
>
>     Bye.
>
>
>         ---------------------------------------------------------
>         LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>
>
>         ---------------------------------------------------------
>         LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>         No virus found in this outgoing message.
>         Checked by AVG Anti-Virus.
>         Version: 7.0.300 / Virus Database: 265.8.5 - Release Date: 3/02/05
>
> ------------------------------------------------------------------------
> Do you Yahoo!?
> Yahoo! Search presents - Jib Jab's 'Second Term'
>
<http://us.rd.yahoo.com/evt=30648/*http://movies.yahoo.com/movies/feature/jibjab\
inaugural.html>
>
>
> ---------------------------------------------------------
> LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio
>
>
> ------------------------------------------------------------------------
> *Yahoo! Groups Links*
>
>     * To visit your group on the web, go to:
>       http://au.groups.yahoo.com/group/LPFM_Radio/
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>

--
Chris Mackerell,  P.O. Box 2241, Wellington 6015, New Zealand
Telephone: +64 (4) 232-4216   Fax:          +64  (4) 232-4218
http://www.owdjim.gen.nz      Mobile & SMS: +64 (21) 238-9861
Email: chris@...                      ICQ# 91488073

Joe Hodge Wanganui,

Music Memories FM 88.6, Wangani Community Based Radio Staion for Senior Citizens

We are a charitable natured organisation.

 

A big Hi to the LPFM group.

 

Does anyone out there have a Tx to sell.  Preferably NRG 1watt. 

Hope to hear from somebody soon.

 

so36jo@...

phone:(06) 347 8143

 

Bye.

---------------------------------------------------------
LPFM Website: http://au.groups.yahoo.com/group/LPFM_Radio



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Version: 7.0.300 / Virus Database: 265.8.5 - Release Date: 3/02/05

Hi,

As far as I know there is no LPTV licensing system

There are some low power licences issued, such as ch41 for Kaitaia
college (-3dBW), ch42 for Pakuranga College Media Studies (-5dBW)

These are in the community TV part of the spectrum and subject to
conditions imposed by the Ministry of Culture and Heritage - ie:
non-commercial community television.

Give MCH a ring - they can advise on whether they can issue a licence
in the ch 40 / 41 / 42 space, subject to the MED - or BCL - confirming
the technical availability of the licence.

ch39 is licenced to Amateur Radio operators - if you're a HAM you could
join up with your local Ham TV club.

You can buy video/audio senders from eg Dick Smith but the power of
these is so low that they would be limited to broadcast coverage of you
and maybe your neighbours house. This would however be the cheapest,
easiest, licence-free way to try out a bit of TV.

And as a rule of thumb, TV costs 10x as much as radio in everything you
do.

Cheers, Jochen



>>> DuffyFamily@... 9/02/05 >>>
Hi Group, just a silly little toying with an idea ?

What is rsm's view towards low power television transmissions?

Thanks M.B. D
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