Hi All I have noticed a various amoumt of personal perseption with regards to the remarks.Here is mine.
Perhaps look at this scenario :When I do my repeater surveys I primarily look at the user requirements. Ant system is designed -for eg: mobile coverage or portable coverage. It has all got to do with "link budget "as a term we use now in GSM in my current job. If the up-link is the same as downlink the transparent coverage is achieved. My one ham repeater is only about 1 Watt into a 0dBm antenna.The reason for this is simple-the path link is sufficient for the Yagi antennas at all the repeaters to make up for any losses. I did some playing around and found that when one puts up a repeater -do your homework and do your installation as best as you can with quality products. If you really want to customise the repeater coverage first use 0 dBd (folded dipole ) in order to guage the coverage and make notes .From there you can then use higher gained antenna and make the notes. Too many people are bulldusted by "high gained antennas that really take coverage away from areas often where improvements are greatly needed. My golden rule with antenna specialising is thus :Energy can not be destroyed , only transferred. Good luck Bradley Glen ZS5WT South Africa Naturn UHF Repeater system --- nj902 <[EMAIL PROTECTED]> wrote: > > > --- In [email protected], "Jim B." > <[EMAIL PROTECTED]> wrote: > "... Another thing to think about-the 3 dB power > change ISN'T what > you're hearing. To really compare apples to apples, > you have to > measure the sound output (SPL) change that the 3 dB > change creates> > Jim Barbour > WD8CHL > (yikes)" > ___________________________________________________________________ > > Huh???? You must be stuck thinking SSB / AM > > Those 3dB are carrier power. What you are listening > to is the > quality of the demodulated signal at the target > receiving unit. > > It is generally accepted industry practice for path > reliability > projection, e.g. Motorola Coverage Acceptance > Standards, that 4dB > C/N is the point at which an FM communications > receiver delivers 12 > dB SINAD and that 7 dB C/N is the point at which > such a receiver > delivers 20 dB quieting. > > Hence, it follows that a 3dB change in transmitter > power [or > increase in antenna gain OR reduction of path loss] > which will > result in a corresponding 3 dB improvement of > received C/N would be > sufficient to: > > A] take a received signal from 1 dB C/N [unreadable] > to 12 dB SINAD. > > -OR- > > B] Take a received signal from 12 dB SINAD to 20 dB > quieting - a > very noticible audible improvement in DAQ [Delivered > Audio Quality] - > a metric that has been used extensively in radio > coverage > prediction and verification. > > > > > > > > > Yahoo! Groups Links > > > [EMAIL PROTECTED] > > > > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
