Friesen@HIS-PHOENIX-MULTICS.ARPA.UUCP (06/05/88)
I am interestead (there has been a little talk about it) if anyone has
used a satellite dish to recieve weather radar pictures.
Aric Friesen
Addresses: Genie: A.FRIESEN ARPA: Friesen%PCO@BCO-MULTICS.ARPA
"Lenny, ya durned fool, ya bought an Amiga!" "Gee George, I squashed the
mouse!"
---"Of Mice and Men"ljdickey@water.waterloo.edu (Lee Dickey) (06/06/88)
In article <880604225715.921660@HIS-PHOENIX-MULTICS.ARPA> Friesen%PCO@BCO-MULTICS.ARPA writes: > >I am interestead (there has been a little talk about it) if anyone has >used a satellite dish to recieve weather radar pictures. > >Aric Friesen Aric, I think you do not need a dish. Mike Gore, here in Waterloo, is collecting images from satelites with a less expensive antenna. He has a low priced scanner from Radio Shack and a small circuit that he has designed himself. He then stores the images in (i think) neo-chrome format, adjusts the gray scales, and then prints them on the printer. Maybe he will tell you about it. For me, his address is magore@watcgl. -- L. J. Dickey, Faculty of Mathematics, University of Waterloo. ljdickey@WATDCS.UWaterloo.ca ljdickey@water.BITNET ljdickey@water.UUCP ..!uunet!watmath!water!ljdickey ljdickey@water.waterloo.edu
wheels@mks.UUCP (Gerry Wheeler) (06/06/88)
In article <880604225715.921660@HIS-PHOENIX-MULTICS.ARPA>, Friesen@HIS-PHOENIX-MULTICS.ARPA.UUCP writes: > I am interestead (there has been a little talk about it) if anyone has > used a satellite dish to recieve weather radar pictures. Yes, indeed. A fellow here in Waterloo has done so, and will be giving a talk about it at this week's GTIA/Vector II meeting. (Small plug, there.) He built the antenna for his receiver, and the decoding electronics, and feeds the data into the ST for analysis and printing. He recently posted some articles to one of the science newsgroups, but I don't recall which one. Sorry. -- Gerry Wheeler Phone: (519)884-2251 Mortice Kern Systems Inc. UUCP: uunet!watmath!mks!wheels 35 King St. North BIX: join mks Waterloo, Ontario N2J 2W9 CompuServe: 73260,1043
rnss@ihuxy.ATT.COM (Ron Schreiner) (06/10/88)
In article <469@mks.UUCP> wheels@mks.UUCP (Gerry Wheeler) writes: >In article <880604225715.921660@HIS-PHOENIX-MULTICS.ARPA>, Friesen@HIS-PHOENIX-MULTICS.ARPA.UUCP writes: >> I am interestead (there has been a little talk about it) if anyone has >> used a satellite dish to recieve weather radar pictures. > >Yes, indeed. A fellow here in Waterloo has done so, and will be giving >a talk about it at this week's GTIA/Vector II meeting. About 1.5 years ago Antic published a project that would convert satellite pictures that are rebroadcasted on a VHF channel into images for your 8bit, they also showed how to connect it to a ST The circuit was simple, just one IC, with most of the work being done in software. -- Ron Schreiner AT&T Bell Labs ...ihnp4!ihuxy!rnss
magore@watdcsu.waterloo.edu (Mike Gore, Institute Computer Research - ICR) (06/14/88)
By the way, for those who are interested I will be posting a NEW version of my satellite decoder software and hardware to the net sometime during the next few weeks [ I now have an addition that allows use of a stereo tape deck so that signals need not be digitized "real time". The new circuit works for both NOAA and METEOR satellites. Hello Ron, In article <2550@ihuxy.ATT.COM> rnss@ihuxy.UUCP (Ron Schreiner) writes: >About 1.5 years ago Antic published a project that would convert >satellite pictures that are rebroadcasted on a VHF channel into >images for your 8bit, they also showed how to connect it to >a ST > >The circuit was simple, just one IC, with most of the work being done >in software. Yes, in fact I saw that issue. I have a few comments to add here for those who haven't seen the article you refer to. For background, many satellites photes [ and weather maps ] are rebroadcast on various shortwave bands using a format called WEFAX - Weather FAX, FSK 120/240 lines per minute. The Antic article used ONLY a 1 bit decoder - either on or off output - whereas a WEFAX FSK signal can have gray scale info in it - ex shades of gray as well. The Antic decoder connected to the shortwave radio audio output jack and converted the variable frequency audio tone of the WEFAX format into a 1 bit on/off output that the computer used in forming an image. Needless to say with only one bit of output the Antic circuit generated almost useless images of satellite photes [ since they have gray scale to start with ] - Weather maps on the other hand work rather well because they are only black or white - ex without any gray scale - so no detail is lost. One might consider using an analog to digital converter after the FSK decoder they used to get improved results. Another method that might be considered, with some deal of effort, would be to make an FSK decoder in _software_ and then replace the Antic circuit with a filter and a zero crossing detector. Things to consider for anyone thinking of WEFAX is the quality of signal you might receive. Shortwave signals are subject to a whole host of natural and man made forms of interference. Also signal propagation is generally controlled by ionospheric reflection - "skip" - this is a function of transmission frequency - which can , and generally does, wreak havoc with signal quality. For direct reception from the satellite you can buy the receiver and the parts to decode the signals directly from the satellite for about $100 to $150CDN. The signals are "line of sight" and the are VHF FM signals [ 137.5, 137.62 MHZ for NOAA 9 and NOAA 10 ]. The bottom line here is that the signal quality is orders of magnitude better then anything you may likely get rebroadcast from a WEFAX station - unless of course you live next door to one!. At this time I only convert the images into 8 bit grey scale which can then be converted into other formats such as AIM or DAGAS format. Since 8 bits is greater then the 4 bit limitation of the ST display one has to play games with grey scale compression to make the best use out of the ST - however having the extra detail to start with is VERY nice!. --- Of course as Ron says the Antic circuit is EASY to build and it's a good point that I don't want to leave unnoticed. The Antic circuit is also low cost to put together - IF you already happen to have a good shortwave receiver - otherwise it's about the same cost as the more complex circuit I have built. Best Regards, PS - for all those who have sent me mail I am sorry I have not yet replied to many of you - hopefully my follow up postings will help out those who did not get the originals - there are also some minor "bug" reports that have been received, documentation has been fixed and other improvements... - Stay Tuned - # Mike Gore # Institute for Computer Research. ( watmath!mgvax!root - at home ) # These ideas/concepts do not imply views held by the University of Waterloo.