larry@extel.UUCP (03/06/85)
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
rad@fluke.UUCP (Randy Davison) (03/13/85)
> > 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
gd@sri-spam (03/15/85)
Randy, Weather satellite and HF weather FAX reception is something I've been curious about lately, so I was especially interested to read what you had to say about it, but the last half of your message was missing from the copy I received. Would you please transmit another one? Thanks, Greg, WB6DEO
rad@fluke.UUCP (Randy Davison) (03/18/85)
It appears that part of my first answer got garbled in transmission so here is a repeat: 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 mechanical machines or homebrew crt systems. Now the display of choice is a pc driven scan converter. This software intensive approach provides much improved flexibility to receive the wide array of differrent formats and line speeds used by the various FAX services. Apparently for reasons of processor speed the Radio Shack Color Computer has been the computer of choice for much of the software development done to date. Certainly this software can be converted to other machines. See reference that follow for more info. References- 1. There is a journal called "Journal of the Environmental Satellite Amateur Users Group". Quarterly @ $14.00 per year (cost may not be exact) by Raul Alverez (WD4MRJ) 2512 Arch Street Tampa FL. 33607. A must have item. Contains recent news and articles about all phases of WX satellite reception. 2. 73 Magazine Nov and Dec '84. Gives a complete description of a pc driven scan converter including discription of hf(same as SSTV) and WEFAX front ends. Includes sources of boards, parts and software. I'm assembling one of these systems now. Back issues may still be available at a well stocked ham store. 3. "New Weather Satellite handbook" by Dr. Ralph Taggart. Available at well stocked ham stores. The bible on all phases of WX satellite activity. A little out of date in that it doesn't include new scan converter material. Taggart is one of the co-authors of the 73 articles above. 4. NOAA has a coordinator for users of US WX sats. Also publish a newletter quarterly with schedules, formants and other info. Contact is Robert Popham. Try reaching him to request newletter at: Dept. of Commerce National Oceanographic and Atmospheric Association National Environmental Satellite Data and Information Services Washington D.C. 20233 attn: Robert Popham 5. There will be a broad spectrum users conference in the Wash DC are the week of April 15 to 19. Get ahold of Popham for details. Includes papers, equipment demos, amateur displays, tours etc. I hope the above is useful info for those interested in this little known but fascinating amateur/swl activity. Regards, Randy Davison K7VOE
Trow.pa@XEROX.ARPA (04/03/85)
According to the March QST there will be a conference in April that should be of interest to weather satellite enthusiasts. It is called the International Satellite Direct Broadcast Service Users' Conference and will be held at the Holiday Inn at Baltimore-Washington International Airport on April 15-19. For more information contact Robert Popham NOAA CoChairman ISDBSUC, NOAA/NESDIS Washington, DC 20233 202/763-7820.