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An Interactive e-mail Journal In Service To The Radio Broadcasting Community
-- ----------- - ---- ------- -- ------- -- --- ----- ------------ ---------
(Formerly the Internet Radio Journal)
Our Internet Email Addresses:
Submit Articles: ARTICLES@airwaves.chi.il.us
Subscription Desk: SUBSCRIBE@airwaves.chi.il.us
Archive Site Desk: rrb@deja-vu.aiss.uiuc.edu
Editor's Personal Email: wdp@airwaves.chi.il.us
... Thank You For Subscribing ..... William Pfeiffer: Editor/Moderator ...
===== === === =========== ======= ======== ====== =========
For Archive, help, and Other Information, See Info Section at End of Journal
--------------------------------------------------
Articles in this issue include:
DAB for beginners (Norman Mcleod)
Re: Information Sought on Early Radio Broadcasting (Harold Hallikainen)
Micro Radio (Charles E Newman)
Re: RADIO OZ (Robert Smathers)
satellite reception of commercial radio stations (Shaw Mr. G)
------------------------------
------------------------------
Subject: DAB for beginners
From: normac@epunix.sussex.ac.uk (Norman Mcleod)
Organization: Experimental Psychology, Sussex University, Brighton
DAB - realising the nightmare
I fear I am something of a heretic when it comes to 'high'
technology, and a few other things besides. In a less
enlightened age, I should have been burnt at the stake long
ago...
For instance, I thought that to extol RDS as 'the greatest
invention in radio since the transistor' was putting it a bit
strong. I reckoned that RDS would end up being about as
important to the radio listener as teletext is to the TV viewer -
i.e. not very.
Yes, RDS has its uses, but it's hardly set the world alight, has
it? Now we have this thing called Digital Audio Broadcasting -
DAB - looming upon us. Will DAB be another RDS? Or another MAC?
Or another HDTV, still gestating after goodness knows how much
money and argument has been spent on it? Or will Digital Audio
Broadcasting overturn the world-as-we-know-it while we watch?
And if DAB does cause a revolution, what sort of impact is it
going to have on the UK radio broadcasting industry and is it a
welcome one? We need to face these questions now, before plans
are set in concrete for the technical progress of radio well into
the next century. Everybody, not just the wide-eyed technophiles,
should take a close look at the effects of DAB on the structure
and pattern of services which broadcasters can set up.
Radio is never going to be as free as publishing, where the
market rules and anyone who can fund a publication can start one.
Always the expansion of the industry is going to be constrained
by the fact that the amount of spectrum available is finite.
It is never quite as finite as one is led to believe by those
with the power to dish it out in our name, but, yes, ultimately
there comes a point when even the pirates cannot jam any more
stations in!
Spectrum Efficiency
Any new invention which uses spectrum more efficiently than an
older technology without sacrificing any of the older
technology's good points must clearly be a Good Thing.
Now DAB comes into its own with national networks. Proposals
include six BBC and six independent networks occupying 3.5 MHz at
Band III, around 230 MHz. This is much more efficient for
network planning than the current state of affairs on FM, where a
2.2 MHz slab of spectrum is used up by each BBC network.
So country-wide, national networks can use DAB to good effect -
since it is technically suited to this sort of transmission. The
smaller and more localised the service you want, the less
attractive DAB looks. DAB is not capable of providing 'stand
alone' services in smaller markets and rural localities in an
economic manner. You have to buy, and plan for, local services
six at a time.
This is going to make the prospects for developing identifiably
local DAB services to locations outside the big metropolitan
areas very bleak.
And DAB is going to cost broadcasters and listeners alike a lot
of dosh, with no payback in sight for much longer than the
current eight-year licence period.
What is DAB?
DAB stands for Digital Audio Broadcasting. It is a way of
transmitting radio programmes, either from terrestrial
transmitters or from a satellite.
What are the benefits of DAB?
Compared to current-day FM broadcasts, DAB claims to offer the
following advantages:
* sound quality comparable to CD;
* reliable reception for all;
* more efficient use of spectrum;
* simple push-button selection
- no tuning;
How does it work?
In essence, DAB takes six stereo channels, converts them into an
economical stream of digits, and then spreads them about in
frequency and time over a 1.5 MHz bandwidth. Because the signals
are spread about a wide chunk of spectrum, the frequency-specific
signal nulls which occur with mobile and portable FM reception,
causing pops, crackles and fades, only affect part of the DAB
signal, and it is rugged enough to be able to tolerate this.
The digits are transmitted on some 1500 low data rate carriers,
such that for any one carrier the data is sent sufficiently
slowly for multipath reflections to add to the detected signal
rather than mangling it, because they occur within the guard band
between one digit and the next. Moreover, national or wide-area
network transmitters carrying the same modulation can all use the
same frequency band - all the signals just add up with DAB. How
much will it cost?
I am indebted to Mike Thorne, of NTL, for providing me with what
I would stress are projected costs for putting DAB in at an
established transmitting site. This assumes that there is space
for the antenna on the existing mast, and room below for the
apparatus. Costs include a pair of DAB transmitters to provide
back-up (since if the thing fails six services will all be off at
once), a new antenna, and installing six BT stereo lines and
input equipment.
For a single transmitter running 1kW into an omnidirectional
aerial, the capital cost of going on the air is put at 450,000,
plus 70,000 annual running costs, including use of mast and rent
for the building, electricity, BT lines, and maintenance. The
price for an NTL 'Total Broadcast Contract', including the
running costs mentioned earlier and paying back the capital cost
over 8 - 10 years, comes to 25,000 pa per service. This is less
than half the comparable FM costing.
However, better service and more efficient frequency use can be
obtained by using a number of transmitters in a single frequency
network (SFN). The cost of a network of five lower power
transmitters (250W) is around double that of the single
transmitter, which puts it on roughly a par with FM.
DAB Receivers - the down side
Current DAB receivers are substantial racks of equipment designed
for professional investigations. No-one is presently able to
produce a DAB receiver for less than several thousand pounds. A
portable DAB receiver running off batteries is still unheard of,
awaiting another generation, at least, of chip
FREQUENCY IMPLICATIONS
There are two frequency bands where it is proposed to operate
DAB. One is towards the upper end of what used to be the TV band
III, around 226 MHz, where current BBC tests are being carried
out.
The other is what used to be referred to by the military as the
'L' band - just below 1500 MHz. The former Band III frequencies
are looked on as a 'parking' band, for terrestrial transmissions,
while the latter band is more likely to be employed for satellite
transmission.
The intention is that in the year 2007 DAB transmissions will be
moved out of the 'parking' band to take over space in the
familiar Band II (87.5 - 108 MHz) after certain FM stations have
been closed down.
FM STATIONS TO CLOSE DOWN
It's this latter proposal which should ring alarm bells if it
were likely to come about, although frankly I don't think it
will. The prospect of unplugging non-DAB equipped listeners from
services they currently enjoy could only be contemplated when
their numbers were very small indeed.
Remember our history. Look how little impact FM broadcasts made
during the first fifteen years of their existence, from 1955 to
1970, say. FM offered superior audio quality and sold a number
of sets to readers of Hi-Fi News, but outside that small
community FM conspicuously failed to catch on.
I suspect one reason was that you couldn't get either Radio 1 or
the offshore pirates on FM, nor could you get Radio Luxembourg or
any other foreign stations.
Another reason for FM's failure to take off was that sets with FM
were expensive, relatively scarce, and often didn't work nearly
as well as they were supposed to. Add that to the fact that all
you got on FM were duplicates of three BBC AM networks, plus one
local BBC station for the favoured few, and the whole affair was
a sorry flop.
Indeed it wasn't until the late eighties, a few years after
previously-simulcasting AM and FM transmitters split programmes
so that FM offered an expanded choice, that FM became the
majority listening medium for radio. That's more than 30 years
after the FM service started and sets first became available.
There are some who seem to think that all DAB need do is
rebroadcast current programmes in pristine CD quality and sets
will sell like hot cakes. I doubt it.
Unless a significant number of extra programmes are available
ONLY on DAB, I fear the whole thing will be a repeat of the early
decades of FM. There would be no question of DAB reaching the
level of penetration of the market that would make it
politically acceptable to switch FM radio off to let DAB take its
place, until such time as enough expensive DAB sets had been sold
to allow the development of a cheap DAB radio.
Make no mistake - millions of pounds has been spent developing
DAB even so far, and this is not charity work. The development
costs will have to be recovered from the first purchasers of the
sets. Whoever buys the first DAB radios will be in the same
position as the people who copped the first mobile phones or the
first fax machines not so many years ago. They will be paying an
arm and a leg for them. So DAB have got to offer more than the
same old songs, hasn't it?
[Moderator's Note: Comments anyone????? Bill]
------------------------------
Subject: Re: Information Sought on Early Radio Broadcasting
From: hhallika@tuba.aix.calpoly.edu (Harold Hallikainen)
Organization: California Polytechnic State University, San Luis Obispo
In article <2d26ej$7t2@vixen.cso.uiuc.edu> kramer@sosc1.sosc.osshe.edu (Ron Kramer) writes:
>
>Second, I have secured a copy of a Department of Commerce
>station license issued in 1926. The Radio Division of DOC
>licensed both a sending wave and a "receiving wave". What
>was the purpose of licensing a receiving wave length? Given
>the fact that a station was required to identify the receiving
>equipment it possessed, there was obviously some type of mon-
>itoring expectation but what was it that was supposed to be
>monitored?
I wasn't around then, but as I recall reading, all broadcast
stations were required to monitor the 500 KHz ship's distress frequency.
I think all broadcast stations also had to be able to transmit on that
frequency to respond to an emergency. Very unsure of this, but seem to
remember reading something about it.
Harold
------------------------------
Subject: Micro Radio
From: newman@netcom.com (Charles E Newman)
Organization: NETCOM On-line Communication Services (408 241-9760 guest)
What would the FCC charge if they ever decided to license Micro-radio?
Micro Radio would give me a chance to start my own CHR station someday, In
the part of the country where I am, I could make a KILLING with a CHR station,
as there are no CHR stations anywheres near Sacramento. I could start out
with Micro-Radio level license, then graduate to higher-power licenses as
the station made more money. I would then take the profits from the first
CHR station and buy a station in San Francisco and turn that into a CHR
station, stations I would love to get my hands on include KJAZ 92.7, KRQR 97.3,
KBAY 100.3, KKSF 103.7, KMEL 106.1 and KEAR 106.9, among these, KKSF, KMEL,
and KEAR are the best because they all can be heard for well over 100 miles.
------------------------------
Subject: Re: RADIO OZ
From: @triton.unm.edu:roberts@ariel.unm.edu (Robert Smathers)
Organization: University of New Mexico, Albuquerque
In article <2cvjdb$rh@vixen.cso.uiuc.edu>,
Bill Pfeiffer <rrb@deja-vu.aiss.uiuc.edu> wrote:
>
>It originates in Minneapolis Minn at WWTC radio, and is on ANIK-1 (I
>believe) satellite. The LA affiliate is hardly a clear channel,
Bill,
Satellite is ASC-1 (c-band side). Transponder 22 (on a consumer
receiver) Left channel is at 7.92 MHz and the right channel
is at 8.12 MHz. Video is the scrambled Midwest SportsChannel.
Your satellite services guru,
Robert
roberts@triton.unm.edu
------------------------------
Subject: satellite reception of commercial radio stations
From: shaw@ccu1.auckland.ac.nz (Shaw Mr. G)
Organization: University of Auckland, New Zealand.
Hi,
Does anyone know if it is possible to receive commercial radio
stations by satellite in N.Z (or Australia).
I'm interested in broadcasts originating from the U.K. or Australia.
I guess all you need is a dish and a decoder but I don't know who
supplies them.
Thanks
Mike Buckler
------------------------------
mbuckler@chenov1.auckuni.ac.nz
------------------------------
------------------------------
INFORMATION INFORMATION INFORMATION INFORMATION INFORMATION INFORMATION
ARCHIVES
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Thank You.
End of AIRWAVES Radio Journal issue 456.
--
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