Dr.Dish Q&A, Febreuary 16, 1997

Dr.DISH Q & A, February 16, 1997


I have a little question about INMARSAT:
Iīm to build a helical feedhorn for my 1.8m dish. I think the signals from
INMARSAT are RHCP, but what happends to the signals when they are reflected
from a dish? I read in ARRL that the polarization are reversed, so one
should wound a LHCP instead. What is the correct polarization of the helical???
By the way, great tv-program you got, although I have some problems
understanding german.
Regards, Magnus, Sweden

Correct, the polarization of a circular signals turns around, if reflected.
The German company Koeditz (Fax_ +49-561-73911-35) offers a low cost and
high quality feed for INMARSAT. It can be fixed in minutes on a normal
offset dish and has a integrated amplfier (26 dB/ 1.2 dB). Itīs nice to
search on INMARSAT and I hope you get good results. look for the higher band
with air-com.


I live for two years in San Cristobal de las Casas down in the south of
Mexico. Until 6 months ago I had no problems with my c-band dish. Now I get
on a broad level disturībanmces coming and going. I use a 10feet dish with
an older Drake receiver. Clabling is as new and all contacts are clean and
dry. Any idea what causes the signal interference?
L. Seligman

Itīs about same time the military uses on your airfield a small
radarstation. Maybe they try to detect flying Chamula Indios. I donīt know.
But I know you should buy a filter which must be inserted in the 70 MHz loop
on the back of your receiver. Not available in S.C., but in Mexico-City.


Where are the Fleetcom-satellites and what is the purpose of this birds? Are
they receivable in the southern part of Europe?
G. Tierny, Italy

Flt.Comms are using more or less the military airband between 250 to 300 MHz
and used for military communications. In Europe reception with a good
Discone and a sensitive receiver is possible. Without amplifier and short
and high quality cables the signal comes up slightly above the noise.


Thanks a lot for yesterday tv-show. We wish you would get access to the
Hotbird. Why not? Itīs the only program in Europe or in the world of this
kind and we enjoy every minute of it. Why do you not finance it by
commercials. Are the satellite industry not aware of this?
Now my questions: you mentioned a General Instrument receiver which works on
digital and analogue signals. Will this receiver work also in Europe?

N. Papanicolaou and 18 dxers from Greece

To your question: the GI-receiver canīt work in Europe, Fixed transponders
and 60Hz are the reason. Just wait until a European company getīs awake and
do the same nice work. At the moment only two companies developing such a
device and we only can hope. But believe me TELE-satellite magazine or
drdish@tv will be the first to report this.


It is worth to buy today a d-box for DF1 and for the search of other channels?
G. Ziegenruecker, Germany

Like all other digital receivers which official sold in difgferent countries
you will depend on the good will of a pay-tv mafia. This people promised you
the reception of a national package. This is all. No guarantee is given that
you can receive all free to air channels besides the national pay-tv
package. Your receiver is can be modified at any given times by the
provider. In some countries one of your duties is to connect this receiver
to the telephone-line. The provider could control you viewing behaviour and
even sell the results to a third party. Greetings from 1984! If you ask me
if it is worth to use such a receiver for DF1 I can give you only my
personal (subjective) opinion. Most of the movies are from the stone-age and
shown many; many times on public tv. Even a thematic-channel als the
Classic-Channels shows very old material and the sound is awfull. I like
Bernstein, but not the repeat no. 104 of a very old concert with audio
technics from the dark past. Theo Lingen and Hans Moser must have signed a
contract with mr. Kirch directly in heaven or it is the first proof of
re-incarnation. Never I would spend 50 Deutsch Marks. I donīt like R.Murdoch
either, but he is clever enough to know waht people likes to see for their
money and he got it.


Can we expect in your series of articles about spying via satellite a little
bit more information about decoding the signals and receiving earth images
(I donīt mean the weather images of NOAA and METEOR)?

Yes, I am working hard on this, but it is not just like to break a EuroCrypt
card, so I depend on inside information and this can take a time. To make
some ad for myself (like the people in the talk-shows): during 1997 the
german publisher FRANZIS will print the whole series as a book.


Living on the border to Germany and the Netherlands it is nearly impossible
to find a dealer which is able to tell us which equipment is needed to
install a ku- and band dish in Tunesia. All we get is some offers of cheap
ASTRA dishes as answer of a clear question. We would like to install at our
premises in Tunesia a satellite dish, able to provide our guest with
internal channels. Where are all this companies from the past who did such a
job with a lot of knowledge. Our first installation at our hotel in Portugal
came from Megasat in the UK, but this company is gone when Astra came.
HCG-Holding, Belgium

Not all of them are dead. Try Microwave Components (MWC) in Alfter near Bonn
and ask for Mr. Zimmermann. One of the last surviving dinoīs from the old
days with practical knowledge about the reception of satellites in Tunesia.
I donīt have a fax-number at hand but the ptt-information should help.


Dr.Dish (Christian Mass)
Editor of TELE-satellite magazine
Producer of drdish@tv, Europeīs first satellite info-channel

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