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From: rad@fluke.UUCP (Randy Davison)
Newsgroups: net.ham-radio
Subject: Re: Fun with Weather Satelites ??
Message-ID: <1344@vax3.fluke.UUCP>
Date: Wed, 13-Mar-85 15:45:58 EST
Article-I.D.: vax3.1344
Posted: Wed Mar 13 15:45:58 1985
Date-Received: Thu, 14-Mar-85 06:17:49 EST
References: <43300002@extel.UUCP>
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 126

> 
> I am seriously considering putting together a weather satellite receiver
> for 1691mhz and have 2 questions which perhaps some individuals in
> net-land could help on.  I will summarize any mail received though I
> hope most reply will be to this group so everyone can share.
> 
> First question:  Is there anything of interest transmitted other than
> cloud pictures and service information?  Weather maps and radar
> summaries would be very nice.
> 
> Second question:  Where can I get info on other services offered by NOAA
> such as:  weather maps maybe via HF fax,  video from local radar sites
> (somehow the TV stations get it I suspect via a dial up line), and any
> other public domain weather information.
> 
> With the TVRO signals due to be scrambled maybe this info might be
> useful someday to others on the net.  Also my display device will be
> a PC so there could be some fun software to share.
> 
> Lastly should there be enough interest I would be willing to serve as 
> a clearing house for a mailing list on the subject provided I can get
> to the users of interest from my network (usenet) connection.
> 
> 73
> 
> Larry Pajakowski
> UUCP:  ihnp4!tellab1!extel!larry
> TELCO: 312-291-4991




Here are some answers to your questions as well as some general info
I think you and others might find useful.

First, satellites only transmit cloud pictures.  Polar satellites
transmit a continuous strip of alternating visible and IR lines.  Geo-
synchronous satellites transmit direct quarter-earth photos as well as
gridded polar shots reformatted and processed on the ground.

HF fax provides a varied menu of retransmitted satellite photes, weather
maps and news items.  I have enjoyed watching hf wx maps come in from all
parts of the world.  the USSR and PRC especially transmit maps that are
easy to receive and fun to watch.

Finally, Radar summaries are available by phone.  I haven't tried that 
personally yet.

Here is some general info that might spark interest in FAX and WX satellite
reception:

Satellites- There are two types of satellites available for use- polar and
geosynchronous.  The polar satellites are in high inclination orbits so that
they cover all parts of the earth twice a day as the earth rotates under
them.  US satellites are on 137.62 and 137.5 Mhz and can be easily heard
using a scanner with whip or ground plane antenna.
Russian satellites are on 137.15 and 137.3 Mhz and run even higher power
than US types.

The geosyncronous satellites are in place above each country that put them
up so basically only the US satellites can be heard.  The Japanese, Russians
and Europeans all have geosynchronous satellites in place.  The US GOES
types transmsmit on 1691 Mhz with FM modulation in the same format as the
polar types.  Output power is quite low so receiving stations must be
elaborate.  Dishes as small as 4 feet can be made to work with low noise
preamps but 6 to 9 foot diameters provide more margin for losses etc.
It's customary to get a polar receiving and display capability up and
running first and then to use the vhf receiver as the IF for the S band
receiver.

Receivers- All satellite transmissions are in FM with various deviations.
The best compromise bandwith for all types is +- 15 khz. (30 khz total)
You can receive the satellites just to hear them on a standard narrow band
scanner but a picture displayed would be badly distorted.  It's easy to put
a wide band filter in a scanner if that is the receiver chosen.  There are a
number of receive options available.  See references that follow.

Display-  Up untill recently it was difficult to display FAX.  The choices were
converted surplus