The Cost and Value of VHF NAS radio stations
LBP
narrowband FM up on the Goldy
and it got me wondering how many people would listen to these
transmissions
and also which VHF NAS band would be the better choice i.e. 70, 77
MHz, 151-152 MHz or 173 - 174 MHz VHF NAS bands
In Melbourne the popular VHF NAS band is 151 - 152 MHz
I was looking at how many stations have taken up licenses and are on
air.
In Melbourne and we have 13 stations in the 151 - 152 MHz band and a
couple in the 173 - 174 MHz band.
Sydney/Canberra have something like 25 + stations operating in the 151
- 152 MHz VHF NAS band.
So it certainly seems like there's been a high take up of these
licenses and of course VHF narrowband FM offer certain advantages
over MF AM transmitting stations.
The most obvious one being the sheer size of antennas -
For a MF frequency of 1692 KHz (177 metres mediumwave) a quarter
wavelength is 44.32 metres = 135 feet.
For a VHF high band frequency of 151.975 MHz (1.974 metres VHF) a
quarter wave antenna would be 49 centimetres = 1.5 feet
MF AM also has a much higher risk of RFI - especially if you're
running at max legal RF power of 400 watts
whereas high band VHF narrowband FM has a very low risk of RFI with 50
watts up the stick.
Also, transmissions in the VHF Land Mobile band using narrowband FM
can carry quite a distance -
with a TX / Antenna located at a reasonable height you should be able
to achieve city wide coverage.
But these tickets don't come cheap...
Getting started - the cost of putting in your license application:
Note 1: The issue charge is $492 for operation in the frequency band
70–960 MHz. Otherwise an issue charge of $164 per hour is applied
(subject to a minimum of $82).
*The issue charge will be $123.00 if the time taken to issue the
licence is less than 45 minutes and the charge will be $492 if it
takes more than 45 minutes.
The annual licence tax amounts
70 to 399.9 MHz 25 kHz bandwidth (narrowband FM) $1,725.50
From the ACMA web site
http://www.acma.gov.au/WEB/STANDARD/pc=PC_1288
VHF NAS technical parameters
VHF NAS station transmitters, in a technical sense, operate under
similar arrangements to land stations in the Land Mobile licence type.
Detailed information about frequency assignment for land stations is
provided in the Radiocommunications Assignment and Licensing
Instruction Frequency Assignment Requirements for the Land Mobile
Services (LM 08).
The technical parameters that apply to VHF NAS stations are:
a maximum Equivalent Isotropically Radiated Power (EIRP) of 83 watts;
an emission bandwidth of 16 kHz (in the past, more than 16 kHz was
permitted but new services will only be allowed a maximum of 16 kHz);
and
Radiocommunications Standard (Analogue Speech (Angle Modulated)
Equipment) No. 1 of 1995.
The band segments employed for VHF NAS are:
70.00000 to 70.24375 MHz and 77.29375 to 77.49375 MHz (segments A and
G of the VHF Mid Band Frequency Band Plan [70 to 87.5 MHz]) and
151.39375 to 152.49375 MHz and 173.29375 to 174.00000 MHz (segments F
and W of the VHF High Band Frequency Band Plan [148 to 174 MHz]).
Assignment of VHF NAS are restricted to the segment 151.39375 to
152.49375 MHz unless this segment is unavailable.
VHF NAS frequency assignment criteria
Frequency assignment criteria for NAS stations in the VHF bands are
the same as those for standard single frequency land stations in the
land mobile service with the exception that transmission may be
continuous. Care will be taken by the ACMA regarding intermodulation
products between VHF NAS stations and International Maritime Mobile
(IMM) channels. While mobile receivers are not normally protected from
interference, IMM services are primarily safety-orientated and will be
protected, especially in areas where a NAS station site is in very
close proximity to IMM equipment.
PonchoRose
The VHF NAS topics is a very interesting one - it is my view that
these licenses/services were in their prime in the 1990s - because the
internet had not taken off yet, so ethics services would offer a radio
station that didnt exist anywhere else.
Furthermore, I knew many ethnic NAS operators here in Sydney that made
good money ($100,000 or more per year) from their non english language
service. Listeners were happy to buy these off band VHF radios and did
in droves!
However with the rise of the internet, online audio streaming and
ethic satellite services - the value or usefullness of NASs has thus
reduced. These days, certainly paying a few grand a year for a licence
is not great value - infact you can obtain a streaming licence from
APRA (streaming copyrighted music) for less.
The 151-152 MHz services are most popular because in most cap cities -
this spectrum was the most available, where as 70 Mhz and 173 Mhz have
been un-useable because of their closeness to FTA TV Channels.
But on the whole, I think Australia is better off having had NAS
services to provide for many non english communities in Australia.
Station X
Up here there has been no where as much take up of these types of
services. There is a Chinese one and a Arabic one licensed but not on
air as far as i know.
Some serious debate has been had in the family here over the pros and
cons here on using them. Why they favour the vhf ones down south I
don't know as the fees are the same. The advantage in the lower
frequency is less picketting when mobile. The downside of all of these
is the audio. Even though it is largely thought of as equal to AM
radio (minus static) it isn't totally true. Then there is the fees one
year as a VHF NAS equals 4 years of renewals for an MF Nas!
Aerials might be bigger but you are looking for crappy land to put
them on not a pole on the ridge where every rich prick wants to live!
Also the diference in frequency blows the EMR thing out. 400 watts of
AM power has no where near the same effect as 400 watts of VHF power
on the human body. Yes I know it's only 50! Shhhh! In simple terms the
EMR problems ramp up the higher you go.
From what I can gather the ethnic groups operating these down south
don't care about quality much. Plus they are on the older scale and
thus hearing has changed. It's a fact that the older audience hate
bass. So as long as they can understand what they are saying - go for
it!
To me it's not an opinion I share. I'd rather them sound as good as
they can for what they are. Here for example I run the Inovonics 222
so my audio is rolled off at 5khz. Some would say that's crap for AM
but it's a known fact that your average radio winds it off at 3.5khz
anyway. It's just a design thing. That is no reason for using crappy
audio files infront of it too.
Bottom line LBP. Get the MF Nas or the SW Domestic (even cheaper).
Opha-Jee
"Station X" <ad...@stationx.com.au> wrote in message
news:31b01b4b-b6b4-46e9...@z1g2000prc.googlegroups.com...
I'm still thinking about the pros and cons of VHF NAS. The fact that most
normal people don't have radio's that can tune to these frequencies is a
powerful disincentive to me to want to use this park of the spectrum.
Having said that, for those truckies and others who have suitable radios,
their might be a case for narrowcasting to a niche audience. But this is
OPEN narrowcasting to a very CLOSED community in some ways.
Licence fees are much higher for VHF NAS - yuck! If you know you can make
money out of your narrowband operation, as many ethnic narrowcasters have
done and still do, fair enough. I have also discovered that the equipment
for transmitting on these frequencies, especially above 136 MHz, is quite
pricey. Well, that is not surprising when you consider that a 25 or 50 watt
FM-band (88 to 108 MHz) Txer is going to cost a couple of grand.
Narrowband frequencies with a low bandwidth are not great from music
broadcasting. This suits the ethnic broadcaster who is playing a lot more
talk programming for their target community who need information more than
entertainment, especially they older generation who are used to radio being
a primary info source. But there are tools that could make music
broadcasting a little more attractive on these frequencies.
Sites - I don't think there is much difference here between MF and VHF NAS
licences. Both will benefit from having a good antenna on a decent site.
I'm pretty sure that MF NAS will cover a wider area than a VHF NAS would.
Why would I use a VHF NAS licence? Possibly to link LPONs in a network
across an city area. Perhaps to broadcast a purely info service, possibly
even a looped service targeted at those who use these exotic frequencies -
mostly men in my assessment. Ethnic listeners will buy specialist radio
receivers to hear their favourite channel in their language, but
English-speaking aussies will not generally do this. They'd just say - if
my old radio in ute can't get it, then stuff it! I can imagine using a VHF
NAS, but an MF NAS on a lower frequency would potentially excite me more
with the prospect of reaching a larger number of people. Running at 50
Watts with smaller and inevitably less efficient antennas would be enough to
out-perform an LPON and probably a VHF-NAS in reaching more middle of the
road people across the coverage area.
More photos posted on ANNRO's Facebook page!
Station X
MF NAS is good for 10k radius then, hearable out to 30/40 k etc etc.
VHF NAS on a high hill will be better than that. But you have two way
radio sound at best.
Atleast MF NAS setup properly can sound like a SW service. Minus the
skip noises obviously! I'm talking about the 5khz freq response. Even
the average AM radio does it's best to roll off at 3.5khz.
LBP
about digi radio and
talky radio just didn't do it for me.. I like the DIY aspect of
analog radio and the sector that
interests me is LPON, MF and VHF NAS, HF Dom as well as off book
radio.
Interesting subject is the pro's and con's of VHF NAS.
Pete I think you can get quite good sounding music audio out of the
two-way land/mobile band
using radio transmitters with a 16 KHz bandwidth on narrowband FM.
I've done tests with some apparatus and I am quite pleased with the
results.
The key is to correctly couple your audio output into your
transmitter.
Sure it won't sound like Classic FM but on 2-way handhelds, mobile
radios and scanners it will sound fine.
This is not meant to be a super HiFi expedition and I think a VHF NAS
station could be quite inventive
and reach a city wide coverage area.
VHF NAS does not have to be ethnic language station - look at Only The
80s by Disco Dan
For $33.20 per week (annual license tax) it's not an overly expensive
hobby and you could have a lot of fun with it.
The key is to keep all the other input costs down - such as install
the transmitter at your house/flat
with the antenna on or in the roof. No extra real estate leasing
required if you do it this way.
High band VHF will reflect and bounce it's way between objects and
buildings (of course UHF is better for reflections)
and even if you're not on a hilltop you can still cover some good
ground.
My test transmissions (on another band but closly related) achieved
good results from the transmitter
site to the city - a distance of 12 km and this was done with a
stealth antenna.
The reason so many MF AM transmitters aren't on the air is because of
the practical considerations
involved with installing a transmitter, antenna mast and good ground
mat or counterpoise.
So thinking about the cost in weekly terms of $33.20 to cover the
license fee - it's not really an expensive
hobby - especially if you operate the TX from your home base.
Instead of going out for lunch twice a week - take sandwiches into
work and use the cost savings to
run your VHF NAS station :)
The key to happy hobby radio is to keep your costs down - DIY from
home.
LBP
narrowband FM (25 KHz channel spacing)
it's said in context within the land mobile radio space and it's
limitations within that space.
VHF NAS is without doubt no HiFi medium - it's crunchy compressed
narrowband that works ok on a 2 inch speaker
in a held held talkie.
Can't compare it to an iPod - really it's walkie talkie band radio -
so direct inject the audio and away you go.
Now the other thing is that narrowband FM 16 KHz deviation with 25 KHz
channel spacing requires a huge less power
to cover the distance than a comparable VHF FM 75 KHz deviation
broadcast station.
The receivers for narrowband VHF FM are a lot more sensitive and also
have better selectivity whereas broadcast receivers
are inherently deaf to a large extent.
Also VHF top band 151 - 152 MHz signals behave differently to VHF 87.5
- 108 MHz and of course UHF has it's own unique way of getting around,
especially the way the signals can enter into buildings through
windows and deflect all over the place because of the smaller
wavelengths involved.
Pete you're the radio guru maybe you can elaborate about the
differences of signal propagation with VHF low and high bands and UHF
parts of the spectrum.
Station X
The VHF Nas option is the most expensive option. Say you get into a
comms site where they want 300/month for site rental. Then the license
fee every year in the order of 1600 bucks! Yes power is 50 watts not
400 granted!
The same amount of sweet talking could get you use of a farmer's back
paddock for a carton. I agree the bigness of the actual aerials for MF
Nas are a little scary. But you need to weigh it all up with what you
get! Setup properly a shortened aerial can work ok reasonably. Then
you get a fighting chance at getting into a few cars! Something you
can forget about on 152 mhz or VHF Hi band Nas. In Dan's case he gets
a little chance at being on Jap radios in Jap cars.
The difference between 77mhz and 152mhz for VHF NAS is better coverage
for mobile use. The picketting seems less. Thus the "perception" of
better coverage. I think the 152 is favoured due to aerial size. Then
the audio quality issues with VHF Lo/Hi band NAS.
As mentioned before somewhere. The audio is largely concidered to be
the same as AM without the static. But this is a litttle untrue. Great
debate has been had here over that. What is important is to know the
pre-emphasis that is used with the brand of gear you are using. In two
way radio world mixing Philips radios on Motorola repeater bases is a
bad idea!
The point being that even though they say it's direct in various
manufactures deal with the response curves in different ways. As has
been the topic here - for F##k sack what are we doing here? This is on
gear that is meant for - Hello mobile 2 are you there?
Having said that I have a scanner from Dick Smith that lets all the
audio frequencies through. You wouldn't know listening from the
speaker. Some filter off the bottom from 300khz down - some don't. In
two way world this is where the subtones are for decoding different
users.
You need to know your way around this stuff to get the best results
you can. Then as has been discussed with here some base gear doesn't
use FM it's PM. Don't quote me here but they are clsoely the same
thing but not exact! PM is really squeeky.
After you dodge all these bullets you find yourself needing something
that will put out 50 watts all day every day! Sorry that's NOT an old
Philips Two Way! Your now into Repeater Base Gear. Get ready for a
3500 dollar unit!
To be more specific to Dan's thing LBP. We have yet to fully complete
it. It's only going as far as his link TX to the hill. Listening on
that to me is telling me it's not all it can be.
Mate at least the MF NAS Spec is so close to what you expect for AM
it's not worth arguing! I've actually found if you process for the SW
5khz spec you can really crank it out harder. This is because you
aren't pushing the wider audio out which the RXer rolls off anyway.
briang
"Station X"
Having said that I have a scanner from Dick Smith that lets all the
audio frequencies through. You wouldn't know listening from the
speaker. Some filter off the bottom from 300khz down -
***Eh??????????????????
Surely 300Hz!!!
Brian G
Station X
uniden.
plug into the headphone socket with a nice pear of cans
and you will hear everything
LBP
again today and the results were less favorable
that what I had previously imagined.
With a test signal on UHF with just a few watts RF output and a ground
independent dipole in the roof I achieved quality results with a
transmission
range / radius of between 2.5 - 3.0 km from the transmitter site.
Beyond that distance the signal drops off sharply and is very touch
and go.
So I am now convinced that if you want to get value out of your pricey
VHF NAS license then you're going to need to have your
TX and 'tenna up on a hill top/mountain summit/tall building roof or
on a 150 foot mast.
Then an STL will be needed and unless you own a house on a hill you'll
be up for site rental fees and the whole things looks
like it's getting out of hand.
Perhaps it's better to go off book :)
Pete I ain't knocking MF NAS and HF Dom - they're top choices and you
get chunky levels of RF to get your signal out
400 watts 1696 KHz and 1000 watts 2368.5 KHz this is plenty of power
to knock the socks off the Goldy !!
This is my Top 5 license choices for Hobby Radio in Australia as it
currently stands...
1. HF Dom
2. MF NAS
3. VHF NAS
4. LPON
I think the shine is fading for LPON - one can't help but feel the
clouds are closing in on the whole LPON with ACMA and 2013
Station X
briang
"Station X" wrote
why does this surprise you brian?
*****Look again at the original post:-
"You wouldn't know listening from the
speaker. Some filter off the bottom from 300khz down"
300 khz down,I think not!!!
300 Hz I think so!
Brian g.
Station X
If you wack audio straight into the TXer on a Two Way everything goes
out. This is the place the Sub tones are injected. You can "sort of"
treat this as flat (well debatable concidered against the whole dev
level) if you inject stuff higher it will go through too.
The mike audio is pre-emphed and filtered so it can sit on top of the
subtones. So the lower bassy voice tones are filtered off so to not
interfer with the subtones. The pre-emph used on the voice part varys
for different makers. So using all Motorola or Philips etc is best!
Not all (but usually) the radios on the recieving end do the reverse
and filter all the 300hz and down audio off before anything gets to
the speaker.
For cheapness reasons and the scanner i got is that. They must have
just ommited the 300hz and down filter curcuit! Bonus for me! Wack the
earphone socket into a Hifi system and everything is there.
Annoying as all shit when listening to the fire brigade as they use
higher tones and loud (even for a wide band system).
But when listening to Dan's 77.4 The 80's it thumps nice! Obviously
the decision has to be made about how much bass he puts out giventhe
devices that are potentially going to be listening!
This is but one little issue you have when trying to use something
designed mainly for talking to mobiles for a music system.
Take Note LBP!
A world of pain awaits if you go the VHF NAS option. There is no
simply wacking a couple of two ways together!
At least all the AM options give you comparable audio to what is
expected frome these modes! And the chance to be in some cars!
LBP
tones is interesting
and also how the receiver compensates for splitting the voice audio
and the sub tones
makes for a curious (and tricky) picture for the would be VHF NAS
caster.
Suddenly VHF NAS don't look so pretty.
Pete I have no plans to go down the route - however I was curious
about the whole VHF NAS thing
and the way stations are going about it and their expectations for
listener numbers etc
Pete are you able to tell us about the set up for Only the 80s 77.4
MHz VHF and how they do it.
What are they using for a 'mitter and 'tenna etc.. and how are they
direct injecting their audio into the TX?
If an import JP car has a receiver that works the JP FM band 76 - 90
MHz and they tune in to 77.4
up on the Goldy - because it's narrowband and the receiver is wideband
- does the audio level
sound muted i.e. way down in level or does it sort of work?
Station X
There is a long way to go yet.
Station X
radio. Obviously not as loud as a proper FM station. Then you must
understand the Two Way Spec (which VHF Nas must do) would limit the
audio to voice frequencies so that would roll him off at the same
4.5khz or even a little lower like 3.5! So it sounds like AM radio
with no crackle!
The Jap radio idea will only work while Dan hasn't got some one close
to him here on the Gold Coast. The day someone gets a service on even
the next 25khz slot up or down he's toast! This is beacuse a normal
broadcast radio is looking at a 100khz +/- window. After all it is an
FM rx made for Japanese FM. Scanners will be ok just the Jap car idea
will be stuffed!
LBP
thread was because of something I read about 77.4 VHF the 80s
and the impression I got was that they were on the air with it.
Anyway - I know these topics go around and around and become tiresome
after a while so I suppose it's best we leave it there.
Cheers mate,
LBP
rjvi...@gmail.com
Fred Smith
broadcasting antenna and the max allowed power output from the
transmitter might get you 50+km, if the receiver antenna is good.
> And what would be the quality like if are broadcasting music on it
modern FM transmitter will do the full audio spectrum allowed (up
to 15kHz?). So pretty good, the limit will be noise at the
receiver's location. Don't know if NAS's are allowed to do stereo,
haven't heard any. Please turn off the compression.