There is something wrong with your SM, then, as it should not show a deviation of 15 kHz on a signal that is 15 kHz P-P unless it's only deviating in one direction from the carrier.
The +/- 4 kHz sounds about right. But, it should be centered around the carrier frequency of 157.740 (Or, on 157.736 and 157.744). It would also equate to a P-P of about 8 kHz as there is nothing but a shifted carrier involved. Regardless, I suspect none of this relates to your problem. If it's only 75 yards from you, I bet it's a very weak spur. It's likely down far enough that it's legal, too. If that is the case, the only thing that will solve it is putting a filter on its TX to notch your repeater RX frequency (good luck getting that to happen if it's not on the same site - and often if it is on the same site). Joe M. Tim Sawyer wrote: > > > My service monitor (HP 8924C) has both a deviation meter and an > oscilloscope to display the demodulated audio. Both the numbers on the > dev meter and the peak to peak on the scope read about 15 Khz. > > I see another paging system (152.84) that shows the same 15 Khz dev, and > a bunch of other ones that show 5 Khz dev. > > -- > Tim > :wq > > On Aug 21, 2010, at 12:18 PM, MCH wrote: > >> >> >> Before you said 15 kHz P-P (IOW bandwidth). Now you're saying 15 kHz >> deviation. 15 kHz deviation would be way too high. >> >> Joe M. >> >> Tim Sawyer wrote: >> > >> > >> > I haven't noticed a hum. There's more of a scream on it. >> > >> > It's POCSAG. Is that analog? >> > >> > The dev is basically 15 Khz but there is, what I going to call splatter >> > that is like 30 Khz. >> > -- >> > Tim >> > :wq >> > >> > On Aug 21, 2010, at 10:14 AM, MCH wrote: >> > >> >> >> >> >> >> Many times (but not all), there will be a grungy sound with the spur. >> >> Think of a very loud 60 cycle hum. >> >> >> >> And 15 kHz is higher than normal. I think the typical shift is 5 kHz >> >> (+/- 2.5 kHz) if we are talking about digital paging. Analog might >> be 15 >> >> kHz, as the bandwidth limit would be 16 kHz. >> >> >> >> Joe M. >> >> >> >> Tim Sawyer wrote: >> >> > >> >> > >> >> > I'm not sure what you mean by grungy. What are you getting at? >> >> > -- >> >> > Tim >> >> > :wq >> >> > >> >> > On Aug 21, 2010, at 6:59 AM, MCH wrote: >> >> > >> >> >> Does it have a 'grungy' sound to it when you hear it on your input? >> >> > >> >> > >> >> > >> >> > >> >> >> > >> > >> > >> > >> > >> > >> > ---------------------------------------------------------- >> > >> > >> > Internal Virus Database is out of date. >> > Checked by AVG - www.avg.com <http://www.avg.com> >> > Version: 9.0.783 / Virus Database: 271.1.1/2746 - Release Date: >> 03/14/10 03:33:00 >> > >> > > > > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> 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/
