So according to that low VHF is less blocked by buildings but does not penetrate inside them. What then is its highest and best use?
For instance, how could it be used in your spectrum utility ideas? And who would likely compete for it? I'll bet Google could come up with something, simply since they are bright network guys with oodles of money.
- Tom Craig Birkmaier wrote:
At 8:31 PM -0500 11/17/07, Tom Barry wrote:Dale Kelly wrote: Therefore, it was necessary to temporarily utilize manyout of core UHF DTV channels. The FCC, after learning that the VHF band hadvery little auction value, also made a number of high band VHF DTV assignments in congested RF areas.I think this was discussed here before and it seemed that low VHF especially (2-5?) was unattractive for for digital TV. Would there be some good use for that if it was cleared and auctioned?From Wikipedia:VHF frequencies' propagation characteristics are ideal for short-distance terrestrial communication, with a range generally somewhat farther than line-of-sight from the transmitter (see formula below). Unlike high frequencies (HF), the ionosphere does not usually reflect VHF radio and thus transmissions are restricted to the local area (and don't interfere with transmissions thousands of kilometres away). VHF is also less affected by atmospheric noise and interference from electrical equipment than low frequencies. Whilst it is more easily blocked by land features than HF and lower frequencies, it is less bothered by buildings and other less substantial objects than higher frequencies.From a California Government report on emergency communications:http://209.85.165.104/search?q=cache:D_FnPHmhyhoJ:www.assembly.ca.gov/acs/committee/c22/hearing/2006/may%25202%2520%25202006%2520-%2520joint%2520hearing%2520agenda.doc+Propagation+characteristics+of+VHF+spectrum&hl=en&ct=clnk&cd=8&gl=us&client=safariOverview of Existing Communication SystemsFederal, state, regional and local agency-specific communications are operating on four different radio frequency bands which consist of low-band Very High Frequency (VHF), high band VHF, Ultra High Frequency (UHF), and 700/800 MHz frequencies. Each radio frequency band presents unique challenges for radio interoperability.Each frequency operating band has both pro and con propagation characteristics. One operating frequency band will not suit the needs of every public safety agency in the state because of geographical and mission operations differences. The low-band VHF will propagate the best in rural areas where the foliage is flush and the topography is mountainous. However, the low-band VHF spectrum is not the best solution for metropolitan areas and in-building penetration. Essentially, the low-band VHF signal will not propagate into building.The high-band VHF spectrum is the best overall spectrum for a statewide radio system for the type of topography in California. However, the high-band VHF frequency resources are not available in California. The UHF is an ideal spectrum for metropolitan areas for in-building penetration and useable for most of the topographies in California. However, the frequency resources are not available in the metropolitan areas of California.The 800 MHZ spectrum is neither suitable nor cost-effective for the flush foliage and mountainous areas in California. The 800 MHz spectrum is very suitable for metropolitan areas and in-building coverage. However, the frequency resources are not available and the Federal Communications Commission (FCC) has mandated that no frequencies be allocated and/or licensed until the rebanding efforts in this spectrum are completed.The FCC has reallocated 24 MHz of the 700 MHz spectrum (television channels 60-69) from the commercial broadcast industry to public safety. However, the public safety agencies cannot use this spectrum until the commercial broadcast stations have migrated to their newly assigned digital modulation broadcast channels. The FCC has extended the mandatory compliance date for the commercial broadcast industry to 2009. The new allocated 700 MHz spectrum has the same propagation characteristics as the 800 MHz band and is not suitable as a statewide radio communication system.So it seems that the low band VHF may primarily be useful for FM broadcasting and emergency services.Regards Craig ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways:- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.
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