ATVStart(1)ATVStart(1), radio, dokumenty strony
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//-->P. C. Electronics 2522 Paxson Lane Arcadia CA 91007-8537 USA©2000Tel:1-626-447-4565m-th 8am-5:30pm pst(UTC - 8)Tom(W6ORG)& Mary Ann(WB6YSS)O’Hara24 hr FAX order line 1-626-447-0489Email: tomsmb@aol.comATV, Where to Start©Aug. 2000Amateur Television, ATV, is fun and easier than you might think to get on with all kinds of applications.Besides sending and receiving live action color video between home ham stations much in the way you are probablyused to with voice on two meter FM, there is; televising live or from tape your ham radio club meetings to thosewho could not make it in person; showing critical locations to local emergency service groups during actualdisasters, parades or races; seeing Space Shuttle video and audio if some one is repeating it from their satelliteTVRO; seeing the edge of space from amateur balloons or rockets as high as 100,000 ft.; getting a pilots view froma camera in a R/C model aircraft or real airplane, and much more.To see your first picture it may be as easy as turning your cable ready TV tocable channel 57 thru 60 and connecting it to a good outside 70 cm antenna of thesame polarity as is used in your area by ATVers. It doesn't get any cheaper or easierthan that to enjoy another of the many modes in Amateur Radio. Make sure your TVtuner is switched tocablechannels when you try it. Unlike slow scan TV - SSTV -ATV standards are the same as broadcast TV and your camcorder so your TV set isyour receiver without the need of any computer or other black box interface. However,Jeff, N8QPJ, demo’s R/C ATVat a Radio Club and televisesthe 70 cm, 420-450 MHz band is the first ham band that has wide enough bandwidththe meeting on local repeater.for ATV and therefore can best be seen between antennas with line of sight.Cable channel 57 is 421.25 MHz, the most common inband ATV repeater output, and60 is 439.25 MHz, the highest frequency used in the band generally for repeater input andsimplex DX. Over the air broadcast TV and cable TV channels are amplitude modulated(AM) video spaced in 6 MHz increments and the automatic frequency control, AFC, in theTV set can usually lock up to within +/- 2 MHz of the video channel carrier frequency. Notethat cable channels are on different frequencies from channel 14 up than over the air UHFchannels and should not be confused. UHF broadcast over the air channel 14 is 471.25 MHzand 57 is 729.25 MHz, well above the 70 cm ham band. So all the commonly used 70 cmATV frequencies (421.25, 426.25, 427.25, 434.0 and 439.25 MHz) can be locked onto andseen with most cable ready TV sets.TVC-4G ATV downconverter tunes420-450 band toch3 if you just wantto try receiving butwith more sensitivitythan a cable TV set.Contact a local ATVer on two meter voice (144.340 or 146.430 MHz typically)and have them send a picture your way. If you don't know of one, call or email us andwe will try to put you in contact. Also check the ARRL Repeater Directory for anyATV repeaters that might be in your area. The transmitting ATV station talks on thesound subcarrier which comes over the TV speaker, and all those watching can talkback on two meters at the same time just like on a telephone. This is great for talkingin beam alignment, commenting on video content, etc.Show the family, the shack,projects, etc.Any code free Technician class licensee can get on ATV. Since the lower thefrequency, the farther the distance, given the same power and antenna gain, the 70 cm band is where 98% ofATVers operate - it is also the lowest cost and easiest to get on. The 902-928 MHz band goes half the distance andso on. ATV frequencies work best with an unobstructed line of sight path between the transmitting and receivingantennas. So the antenna and height is the most important part of the ATV station. Antennas need to be made forthe 70 cm band, preferably as high of gain as possible and the same polarity as is standard in your area. Low losscoax is also a must as it takes 150 to 200 microvolts into your receiver for a snow free picture and you don't wantto throw RF away unnecessarily.1P. C. Electronics 2522 Paxson Lane Arcadia CA 91007-8537 USA©2000Tel:1-626-447-4565m-th 8am-5:30pm pst(UTC - 8)Tom(W6ORG)& Mary Ann(WB6YSS)O’Hara24 hr FAX order line 1-626-447-0489Email: tomsmb@aol.comATV, Where to StartAfter you see your first picture, you will want to improve your reception forDX or get less snow with one of our downconverters and high gain beams - see ourcatalogue page 3 - or go all the way with the TC70-20 Transceiver on page 1. Wealso have 1 or 20 watt modules for those who want to package their own systems oruse them for portable, R/C, rockets or balloon ATV - see pages 2 and 5. With theTC70-20 Transceivers, 14 dB of gain from DSFO ATV-25 antennas and coax lossat both ends you can send and receive snow free video over 100 miles if line-of-TC70-20 all in one box ATV20 watt Transcieversight between the antennas. However, getting line of sight is the trick or waiting fortemperature inversion skip. Non-line-of-sight is not predictable and just has to be tried. How well you do on 2meter simplex is a good indication that you have an ATV path if the signal is strong.Any camcorder or camera can simply plug its composite video and lineaudio into the ATV transmitter. It can be color or black and white - what ever youplug in is what you get out. Composite NTSC video is the standard A/V output inthe USA for camcorders. As an alternative there are many small low cost color orblack and white cameras available now that are made for computers or securityunder $200 that can be used at the home station, mobile, portable, R/C, balloon orrocket ATV. The camera shown is available from us for $99 and is ideal for R/C,hat cams or even the shack. For a wide selection of cameras, we suggest ATVResearch - call 1-800-392-3922 for their catalogue or check out their web site atATV from a R/C aircraft withGPS and call letter ID overlaid$99 color15 video systems capable of up to 2 miles if your application does not fall undercamera fromthe Amateur Radio Rules. Microtek has Part 90 business video links for up to 20us. 1.5” sq., 3miles - 1-888-366-4276.oz, 9V@30ma.For more info on ATV, I suggest reading the ATV section of the 1995 -2000ARRL Radio Amateurs Handbook starting in chapter12 page 46 (W6ORG wrote it).It will give you all the basic information and background for this visual mode ofham radio. Email for our ATV application note list or check page 3 of our web site.The ARRL Repeater Directory lists all the coordinated ATV repeaters in the country- see if one is in your area. Amateur Television Quarterly is also a source of continuingATV information. Contact them at ATVQ@hampubs.comRepeat Space Shuttle video &If you have email, there is an ATV remailer where you can ask questions,audio from NASA Select toreceive info, hear about temperature inversion DX openings and keep up on ATVhams in your area if you orhappenings around the country - it is free.another ATVer has a satelliteTVRO. Repeat weather radarTo subscribe, just send an email to:during significant storms foratv-request@atv.tallahassee.netRACES operations.In the body of the message just put: subscribe atvThis will automatically send you any message sent to the remailer from other ATVers. You can also find localATVers and clubs usually on this remailer.We will mail out free our 10 page ATV catalogue containing everything you need from 70 cm to 10 GHzATV if you call, email or write us your request and are a licensed radio amateur. You can also down load ourATV information, application notes and source links on page 3 of our web site.©Aug. 20002 [ Pobierz całość w formacie PDF ] |
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