Re: Future of UHF CB etc

Jas>>> On Sun, 27 Apr 2008 07:27:19 +1000d, Jason James Blathered on

>>> in48139e32$0$23382$ snipped-for-privacy@pit-reader.telstra.net: >>> >>>>> 400Mhz, future of UHF CB et al >>>>> Discussion:- >>>>> >>>>
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>>> cb.html#post40513 >>>>> See Page 36 of the Pdf download re 12.5Khz channel spacing, see link >>>> within. >>>>>
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>>>>> >>>>> The closing date for submissions is 18 July 2008. >>>> Any increase in operating freq, will cause an increase in path-loss or >>>> propagation loss. There are advantages ie more channels can be obtained. >>>> A rough formula is: Prop-loss in dbs = 32 + 20log km (in kilometres) + >>>> 20log f (megahertz) >>>> To find the difference in path loss due freq increase, keep the distance >>>> the same, then include the original freq in use. Note the answer,..then >>>> insert the new freq. Subtract first value from the second,..and you have >>>> your loss due freq increase in dbs. To obtain a useful value which >>>> conveys an easily, you need to understand decibels (db). For example 30 >>>> db is 1000 times the original figure, 3db is twice the original figure. >>>> Google up a db to linear conversion. >>>> >>>> Jason >>>> >>>> Jason >>> But... but.. >>> The mooted idea is to decrease the channel intervals - that won't change >>> anything but the 'requirement' for radios to be better at what they do in >>> terms of adjacent channels being a problem. >> >> True, there will have to be reduced BW to stop adjacent ch splashing >> dev.peaks into the ones either side. plus any reduction in channel spacing >> will mean less deviation and therefore a degradation of Sig/Noise. >Will this mean the end of those piss poor Uniden radios that have a >front end so open you can hear every transmission in the 400-500MHz range??

Not just Unidens. GME's products are designed deliberately so that additional listen-only channels can be programmed anywhere betweek about 450 MHz and 520 MHz. Dunno if that's by design or just a 'feature' that they decided to use to commercial advantage. I'd say it's by design.

Craig.

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yeah but the Uniden radios will let you hear every signal all at the same time, and on every channel you select so all you hear is a terrible crashing warbling screeching noise and that is not a feature it's by design, a very bad design

Kev

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Kev

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