Filter Options

CaptMac11

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Jul 9, 2019
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16
Location
West Central Florida
I've been investigating the use of filters on my SDS200 & 100 and have a couple of questions...
I live in west central Florida and when monitoring my local county (Pasco) I have an RSSI that fluctuates between 75-90 dBm with good clear reception. Scanning the nest county up (Hillsborough) on both their EDACS and P-25 I get a reading varying from 102-106 dBm with rather scratchy reception. Distance to the antenna for the next county appx 25 miles. After switching through the filters i find only minimal difference in both RSSI and audio. I'm running a Yagi antenna mounted 35' up aimed directly at the transmitter with 65' of LMR 400 coax lead in. Is the reception that I am getting considered reasonable or are there other things that I should look at to improve? What RSSI should I reasonably expect? I have the modulation set to FM on both systems.
I defer to y'all who have more experience than I and appreciate all input.
Thanks
Mac
 

nessnet

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Jan 22, 2007
Messages
471
Location
Kenmore, WA
My take on filters.....

If you live in a strong RF area, filters help. But, it sounds like you live farther out (25 miles) so I'd suggest filter = off or normal.
 

n1chu

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Oct 18, 2002
Messages
779
Location
Farmington, Connecticut
It’s been my experience that RSSI readings are at best subjective. As for filters, I went through all filters on numerous channels and found little or no improvement. So, in my situation, there is no advantage gained from the available filtering. But even if I found an improvement using a particular filter on a specific band, mode, etc., it doesn’t mean it would help others listening to a similar transmission. The adage “Your results may vary” applies here.
That being said, I enjoyed tinkering with the scanner while checking out the filter options.
 

sonm10

Central MN Monitor
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Joined
Nov 19, 2016
Messages
127
Location
Sauk Centre, Minnesota
My take on filters.....

If you live in a strong RF area, filters help. But, it sounds like you live farther out (25 miles) so I'd suggest filter = off or normal.
I find this reduces my far away reception and wide-auto works the best for farther out signals. YMMV
 

Ubbe

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Joined
Sep 8, 2006
Messages
5,044
Location
Stockholm, Sweden
If you have -75dBm from your local site then -102dBm from a site 25 miles away are probably what could be expected.

Lower frequencies below 25MHz can reach around the world but the higher in frequency you go the less range you'll have. At 700MHz and higher you will have a very short range from a transmitter compared to one at 150MHz.

If you need to get better reception then probably a low-noise amplifier will improve the most. It's internal noise level are some 3dB better than the scanners and it will compare to receiving a -99dBm signal. If your total coax lenght adds up to 50ft then it attenuates 2dB and putting that amplifier at the antenna will then add an additional 2dB in signal strenght that would make it a scratch free reception of analog signals.

If changing filter type doesn't alter your reception then you have very little interferencies and wouldn't cause any problem using an amplifier. The Normal and Invert filter settings have the most attenuation so try and stay away from those settings and the Off setting gives the least attenuation. Any interference could make one of all the filter settings giving you the lowest NOISE level, set the display to show it, and the most scratch free reception. With digital signals you look at the D-ERROR value to get it as low as possible.

/Ubbe
 

werinshades

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Jan 21, 2002
Messages
3,502
Location
Chicago , IL
If the reception is good, no missing transmissions don't worry about filter use. If you're having some issues, adjust on the scanner first and if you're happy with the result, read back to the scanner.

As far as all the readings etc., I tend to ignore them unless I'm submitting some diagnostic information to Uniden. I prefer the Simple Views for the reason it has less on the screen. I'm more interested on what's being said, what channel/talkgroup it's on, and if the reception is good. Sometimes too much information is a bad thing, too many are attempting to tweak their settings to reach some "perfect" values, when it might not be necessary.
 
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