This is off topic, but since this list is made up of computer geeks like me :) I think you might find it interesting... on 4/17/02 8:20 PM, ted Spencer at tedspencer@... wrote: > I followed your link and thence the Digital TV links which were interesting > but, in my quick perusal, left me wondering whether the plan is to broadcast > M-JPEG (or something like it) or is it to be an internet-based service? Each DTV transmitter is basically a high speed one way RF modem using 6 mhz of spectrum. The actual usable data rate of a DTV channel is 19.4 megabits/second. The data is all packetized giving broadcasters lots of flexibility as to what type of data we can send (basically anything including FB3 programs!). When we're sending TV programming, the video compression standard is MPEG2 and the audio is Dolby AC3. There are actually 18 different resolutions and frame rates supported by the ATSC digital broadcast standard which range from qualities similar to what you are used to now, up to 1920x1080 HD resolution in letterbox format with full 5.1 channel Dolby AC3. Really good standard definition broadcast MPEG encoders ($45k) can make good looking standard definition pictures with video data rates as low as 1.5 to 2 megabits/second. DirecTV encodes their stuff somewhere in this range. At these data rates you can multicast quite a few standard definition channel with one 6 mhz DTV channel. High definition encoders need about 13-15 megabits to make good looking HD programs, so it's possible to fit one HD and a few SD channel into one DTV channel if you buy good encoders. I just got back from the NAB (National Association of Broadcasters) convention and was specifically shopping for SD encoders. There are very big differences in quality of picture at a given bit rate for various manufacturer's equipment. More money buys you better quality at a given bit rate or same quality at a lower bit rate. > it be (if RF) in the UHF band or elsewhere? Both High band VHF (Ch 7-13) and UHF will be used for DTV. > With a sordid history that includes radio (both on-mike and off), I have a > more than usual interest in such goings-on. I've been doing this for a while too! I'm 45 and I've been in radio engineering since I was 18 and TV since I was 23. So far I'm still having fun!! I'm sure many of you don't recognize my name, but I've been a lurker on this list since it started. I've got the original ZBasic floppy discs from Zedcor and I've also got most of the news letters that Ross Lambert used to do. (What ever happened to Ross?) I even have a copy of the first MacZ newsletter from Zedcor (I think that's what it was called?). Staz did a lot of hand holding back when I was getting started in programming and I owe him a lot. I can't think of any other company that cares about it customers like Staz and Andy! Thanks guys! I've been clinging to FB2 because I know it so well, but I guess it's time for me to learn FB3! If any of you want to make real money, start writing software for broadcast TV automation. We're looking at a system that will automate five channels of playout, satellite records and archiving for our station that needs half a dozen PCs to run and will cost over $150,000 (this includes half a dozen PCs), not to mention ongoing software support and upgrades... That doesn't include the ASACA 16.5 terabyte DVD archive system for offline server storage that costs over 100k or the SeaChange broadcast server that will store 250 hours of 8 megabit MPEG2 standard definition video that has five input channels and seven output channels and costs $200,000. Not to mention the 2+ million conversion cost of our transmitter sites and microwave or the $250k we'll spend for our MPEG2 encoders and multiplexor Yes, broadcast DTV is not for the timid, but we DO have GREAT TOYS!! Thank God for Federal grants, which I've been quite successful in obtaining. :) I'm sure I've bored everyone enough by now. Sorry! Bill Sanford General Manager Director of Engineering bsanford@... 218-751-3407 ext. 115 Lakeland Public Television http://www.lakelandptv.org Watch Lakeland News at 10 on our web site! http://www.lakelandptv.org/pages/lakeland_news/lakelandnewscasts.html