Re: Iraqi TV

[Garrett Wollman <wollman@lcs.mit.edu>]

<<On Fri, 28 Mar 2003 22:36:30 -0500 (EST), Sven Franklyn Weil <sven@gordsven.com> said:

> This is what the BBC-TV does.  The numbers you set your TV set's
> dial to in London are not the same if you are watching TV in
> Hereford, for instance.  The UK uses the UHF band for OTA terrestial
> TV exclusively, by the way.

Most European TV sets don't even show channel numbers.  The set finds
a station, and you assign the number after identifying the station by
its programming.  There are very few countries with more than 5
broadcast TV services serving any area.

As for the need for relays, well, they aren't automatically necessary,
but most countries prefer to license networks of lower-power stations
rather than few high-power stations.  This is particularly important
in Europe where most broadcast signals (regardless of band and
service) are interference-limited rather than inverse-square-law or
radio-horizon limited.  500 kW on the VHF-low band would probably
cover all of a medium-size country but would make the neighbors rather
unhappy.

As for the directional patterns of Iraqi MW stations -- there most
likely aren't any, at least officially.  Most stations in ITU Regions
1 and 3 operate at very high power and without use of directional
antennas.  Many still use ``hammock'' or ``flat-top'' antenna systems.
(See Scott's pictures from last year of the ex-BBC Droitwich and
Moorside Edge sites for some 500-kW stations using hammock and
longwire antennas.)  These antennas are in fact directional, but this
is an artifact of the type of radiator rather than an intentional
design characteristic.

-GAWollman