Leland, you are almost on target. The 6 MHz bandwidth applies to the broadcast transmitter. The microwave systems used to deliver the 292 ASI stream to the transmitter may or may not have a 6 MHz bandwidth. For example the MRC microwave system we use at the station carries 2 HD ASI streams at 19.34 Mb/s each and 1 SD that is a 6 MHz analog TV channel. If you want to see what an 8VBS transmitter signal looks go to Page 3 figure 6 of this article.
http://www.axcera.com/downloads/technotes-whitepapers/technote_5.pdf You are right about the Japanese system, but they have a very limited number of broadcast stations compared to the USA. This allows them to allocate the 20 MHz required for their system. Jim -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Leland F. Jackson, CPA Sent: Sunday, November 02, 2008 12:01 PM To: ProFox Email List Subject: Re: [NF] No digital TV signal? If I understand thing correctly, the Japanese TV networks each have 20 MHz of microwave bandwidth, so Japanese TV stations will stream a mirror image of the digital camera's picture over the air, and the Japanese people will have the highest quality TV picture. In America each TV network only has 6 MHz of microwave frequency bandwidth, so the USA has adopted a compressed digital signal. The signal loses quality the more it is compressed, but it reduces the amount of binary data to be processed, as well as the size of the file necessary to hold the binary information. The standard wrapper used in the USA to hold the digital information is mpeg- 2, I believe. I also see mpeg-4 a lot, which also seem to be popular. In the USA the digital signal is compressed. The more the signal is compress the low the quality of the picture, the lower the amount of digital data processed to create the picture, and the smaller the file need to hold a TV program. For better quality HDTV entertainment, you can stream your own huge files using a Blu-Ray DVD or via a huge movie file located in your computer. Both DVD and multimedia player are popular for delivering high quality video/sound content to an HDTV. A TV station delivers its products much like information is delivered in a computer network. Each USA TV network has 6 MHz of microwave frequency within its designated range to broadcast several streams of content over its channels, (eg multi-casting), using compression to fit it all into its limited 6MHz of microwave bandwidth. The images and sound from the digital camera is wrapped into a mpeg-2 signal for delivered over the network using microwave frequencies, and the picture will be displayed on the HDTV, which has been designed to work natively with a digital signal. There is plenty of change going on in the area of HDTV right now, so I'm hoping I will get the full 10 or 15 years out of my HDTV, before it goes obsolete. LOL Regards, LelandJ Jim Felton wrote: > Leland, go read but thought you might like to see > http://en.wikipedia.org/wiki/Digital_terrestrial_television > > Nucomm and Microwave Radio Corp. (MRC) are the two big players in the > microwave equipment suppliers. They both offer products for Studio to > Transmitter Links (STL) and "Live truck" to station links. There is a > government program being run by Sprint/Nextel to convert all Analog "Live > trucks" to Digital. This was mandated by the FCC about 2 years ago. It > does return part of the spectrum analog microware transmitter currently use > to the government for use in Home Land security and other government > agencies. That project was supposed to be completed by August of this year > but has been extended to I think August of next year. > > Jim > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf > Of Leland F. Jackson, CPA > Sent: Saturday, November 01, 2008 1:01 AM > To: ProFox Email List > Subject: Re: [NF] No digital TV signal? > > The below article give a definition of HDTV signal, (eg digital signal), > and how a digital signal can be used to carry more data over a given > microwave frequency bandwidth. > > http://www.howstuffworks.com/framed.htm?parent=dtv.htm&url=http://www.pbs.or > g/opb/crashcourse/digital_v_analog/ > http://electronics.howstuffworks.com/dtv6.htm > > Regards, > > LelandJ > > > > Leland F. Jackson, CPA wrote: > >> Yes, Nucomm has a patent for digital transmission over microwave analog, >> if that's what your talking about. I'm not qualified to discuss the >> technicalities of how a digital signal is transmitted, whether from the >> broadcast studio to the microwave tower, or from the microwave tower to >> the TV antenna, or from the TV antenna to the HDTV, or from microwave >> tower to microwave tower, etc. There seem to be a lot of R&D in this >> area, so things can change in a hurry. <g> >> >> It does seem that a digital signal is the future for TV, and a high >> definition TV is designed to work natively with a digital signal, so I >> would look closely at the long term cost to purchase a new High >> Definition TV, as opposed tot he long term cost of retrofitting an >> analog TV with a tuner box to convert the digital signal to analog. >> >> http://en.wikipedia.org/wiki/Microwave >> http://www.cnet.com/1990-7874_1-5108854-1.html >> http://www.patentstorm.us/patents/7359450/description.html >> >> > http://blog.digitalcontentproducer.com/briefingroom/2008/05/21/nucomm-wins-p > atent-for-its-cost-effective-digital-transmission-over-microwave-analog-link > -concept/ > >> Regards, >> >> LelandJ >> >> >> >> >> Jim Felton wrote: >> >> >>> Leland, the only frequencies being free up are channels 51 to 88. The >>> digital transmitters are assigned the current frequencies from channel 2 >>> > to > >>> 50. Not all Analog TV goes Black or off air on Feb 17th, Low power TV >>> Stations can continue to transmit for at least 2 years past that date. >>> > The > >>> FCC has not pasted the ruling yet. Come on up to Northern NY and I'll >>> > get > >>> out the frequency analyzer and show what an 8VSB "digital signal" really >>> analog signal looks like. Believe me it's an analog FM signal with phase >>> encoding in the signal and its still 6 MHz wide, just like analog TV. At >>> the station we tell are transmitter engineer he has a High Power >>> > Amplifier > >>> with the Random Bit Generator option, when the transmitter gets out of >>> alignment and subcarriers don't sync up. >>> >>> Jim >>> >>> -----Original Message----- >>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >>> > Behalf > >>> Of Leland F. Jackson, CPA >>> Sent: Thursday, October 30, 2008 11:19 PM >>> To: ProFox Email List >>> Subject: Re: [NF] No digital TV signal? >>> >>> The electromagnetic field contains ranges of energy, (eg waves or >>> frequencies), with various ranges suited to different kinds of energy. >>> For example radio, microwaves, lasers beams, TV signals, etc all exist >>> within their own electromagnetic frequencies or ranges. >>> >>> The switch to digital TV in part is to free up a range of >>> electromagnetic fields previously used for analog TV, so it can be >>> dedicated for use by the government, for example by agencies like >>> Homeland Security during an emergency. The government also has sold >>> some of the analog frequencies of the private sector. Also, the switch >>> to digital TV has to do with improved TV quality for consumers. >>> >>> A High Definition Television, (eg HDTV), is the product being sold, and >>> a digital signal is used to deliver the picture/sound. >>> >>> An example of a analog system is the use of a modem to modulate and >>> demodulate sound over an electric wire. This is an analog system, >>> because it requires the communications to be modulated and demodulated >>> using sounds, much like people talking on the phone. The numbers and >>> letters of the alphabet that are represented by a string of 8 bits of 1s >>> and 0s, or ons or offs, etc are carried over the wires between two >>> computers via sounds. >>> >>> In a digital system, the 1s and 0s, or ons and offs, do not have to be >>> modulated and demodulated into an analog signal. The 1 and 0, or the >>> ons and offs exist in a pure energy state and are transmitted through >>> space, like between two microwave towers or via pure light over fiber >>> optic cables. >>> >>> The new HDTV are designed to work with a digital signal, but during the >>> transition to digital TV, all newer HDTVs come with a tuner that allows >>> the HDTV to show an analog channel. I suppose the tuner will become >>> irrelevant after Feb 19, 2009 for anyone with a HDTV, as all TV will be >>> delivered via a digital signal, so anyone that still has an analog TV >>> will need a tuner to change the digital signal into an analog one. >>> >>> Regards, >>> >>> LelandJ >>> >>> >>> >>> >>> >>> >>> >>> Pete Theisen wrote: >>> >>> >>> >>>> Stephen Russell wrote: >>>> >>>> >>>> >>>> >>>>> On Wed, Oct 29, 2008 at 10:33 PM, Jerry Wolper <[EMAIL PROTECTED]> >>>>> >>>>> >>>>> >>> wrote: >>> >>> >>> >>>>> >>>>> >>>>> >>>>> >>>>>>> don't you need a digital antenna too? >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> No. The bowtie/halo part of the antenna should get the digital signal >>>>>> that's broadcast on UHF. It's an all-or-nothing proposition, though. >>>>>> Weak signals that came in poorly in analog won't come in at all >>>>>> digitally. >>>>>> >>>>>> >>>>>> >>>>>> >>>>> ------------------------------- >>>>> >>>>> Well it is all on the location of the towers. If the new digital ones >>>>> are closer it will be better. My dad found that the digital reception >>>>> was much better than the traditional because the digital towers were >>>>> close to his house and the old ones were on the other side of town. >>>>> Roswell NM. >>>>> >>>>> >>>>> >>>>> >>>> Hi Stephen! >>>> >>>> I think the same tower will host the digital signal. Florida companies >>>> are too cheap to do anything else. >>>> >>>> >>>> >>>> >>> --- StripMime Report -- processed MIME parts --- >>> multipart/alternative >>> text/plain (text body -- kept) >>> text/html >>> --- >>> >>> >>> [excessive quoting removed by server] _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://leafe.com/mailman/listinfo/profox OT-free version of this list: http://leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/[EMAIL PROTECTED] ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
