SDS100 Questions

Dexter2

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What is the difference between Invert and Wide Invert in filters?

Is there a reason why some channels have more than one channel? Example, a person talking on Channel/TGID 2 is the same person talking on Channel 14?

I'm using a Pro 490 antenna, are there any other antennas that would improve a 800 channel Trunked system?

If your listening to one system, can you set Hold to 0 seconds?

I believe I am still missing transmissions - my NOISE ranges 100's-400's and Signal is -40 and -55, but randomly goes high to 33,000's and -116. Any solutions?

Thank you to anyone's help.
 

tvengr

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You usually set the hold to 0 on a trunking site. On a conventional system, if the hold is set to 0, it will flash on the screen so fast that you will not know it is scanning if anything else is. If you set hold to 1, it stays on the screen long enough to see that it is enabled. The Remtronix REM-820S antenna is made specifically for the SDS100 and includes an O-ring to maintain water resistance. That one will give you at least a 6db gain over the stock antenna for 700/800 MHz. You have to be more specific about the channel/talkgroup thing. They could be simulcasting on both a trunking system and a VHF or UHF conventional system. TGID's can be patched together. A dispatcher may talk on several talkgroups for an announcement such as giving out a description citywide or countywide. Are you doing zip code scanning or using favorites lists? If you do a download, you may be scanning a multitude of sites that are not needed and that will certainly cause missing transmissions. What is your location (city, county, state) and what do you want to monitor.
 

Ubbe

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What is the difference between Invert and Wide Invert in filters?
Invert will let the receivers IF section see about 1MHz below the tuned frequency and about 9MHz above it. Wide will change that to about 3Mhz below and 7MHz above the tuned frequency in the IF signal.

For the VHF airband the Invert probably works best as it attenuats FM broadcast more but Wide will let the receiver see more of the FM broadcast signals but will also be more sensitive, if the FM signals are not too strong. The Off setting will have the most sensitivity but could be more prone to interference and desense issues. It all depends mostly of where the strong signals are at your listening position and it is a trial and error thing as the most optimum settings depends of several circumstances. If it was easy to predict then Uniden could have used fixed filter settings.

/Ubbe
 

Dexter2

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Invert will let the receivers IF section see about 1MHz below the tuned frequency and about 9MHz above it. Wide will change that to about 3Mhz below and 7MHz above the tuned frequency in the IF signal.

For the VHF airband the Invert probably works best as it attenuats FM broadcast more but Wide will let the receiver see more of the FM broadcast signals but will also be more sensitive, if the FM signals are not too strong. The Off setting will have the most sensitivity but could be more prone to interference and desense issues. It all depends mostly of where the strong signals are at your listening position and it is a trial and error thing as the most optimum settings depends of several circumstances. If it was easy to predict then Uniden could have used fixed filter settings.

/Ubbe
Thank you, I've been experientmenting with different filters. I still have to learn what airband is mine or that I'm listening to.
 

Dexter2

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You usually set the hold to 0 on a trunking site. On a conventional system, if the hold is set to 0, it will flash on the screen so fast that you will not know it is scanning if anything else is. If you set hold to 1, it stays on the screen long enough to see that it is enabled. The Remtronix REM-820S antenna is made specifically for the SDS100 and includes an O-ring to maintain water resistance. That one will give you at least a 6db gain over the stock antenna for 700/800 MHz. You have to be more specific about the channel/talkgroup thing. They could be simulcasting on both a trunking system and a VHF or UHF conventional system. TGID's can be patched together. A dispatcher may talk on several talkgroups for an announcement such as giving out a description citywide or countywide. Are you doing zip code scanning or using favorites lists? If you do a download, you may be scanning a multitude of sites that are not needed and that will certainly cause missing transmissions. What is your location (city, county, state) and what do you want to monitor.
Thank you, I am listening to Trunking sites. For some reason, I haven't received any transmissions on the one system I was listening to with the given antenna, that is what made me switch and see if that would improve anything. Maybe I didn't have it on right, I can try again tomorrow. As far as the talkgroups, I noticed one minute it would be Channel 20 and then it would be the same person on 46 but separate transmissions not a wide announcement. Are they patched to connect to different units/vehicles? I just have a favorite list, in the beginning I was just monitoring my local transit agency as this SDS100 is brand new to me. I am in New York, so I have both Albany frequencies/systems and NYC.
 

Dexter2

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Invert will let the receivers IF section see about 1MHz below the tuned frequency and about 9MHz above it. Wide will change that to about 3Mhz below and 7MHz above the tuned frequency in the IF signal.

For the VHF airband the Invert probably works best as it attenuats FM broadcast more but Wide will let the receiver see more of the FM broadcast signals but will also be more sensitive, if the FM signals are not too strong. The Off setting will have the most sensitivity but could be more prone to interference and desense issues. It all depends mostly of where the strong signals are at your listening position and it is a trial and error thing as the most optimum settings depends of several circumstances. If it was easy to predict then Uniden could have used fixed filter settings.

/Ubbe
I'm listening to a P25 Phase 2 Trunking. Not sure what type of airband, where do I find that information at?
 

tvengr

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The aircraft band is 118-136 for voice. You will hear things like navigation beacons on 108-118.
 

budevans

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Besides the Civil Air Band: 118-136 that tvengr posted. There's also the Mil Air Band: 138-144 MHz and 225-400 MHz.
 
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WX4JCW

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Is there a reason why some channels have more than one channel? For example, a person talking on Channel/TGID 2 is the same person talking on Channel 14?
The channels are patched together, there is also multi-select where the dispatcher can broadcast on multiple channels at one time
the Dispatcher generally controls both Patching and Multi-Select think of Patching as a two way route of 2 talkgroups merged together by the dispatcher, whoever has one of the patched talkgroups selected can talk and hear whatever is going on on the other talkgroup.
Multi-Select is one way for use when dispatching a call or letting all channels selected know something important is going on
 

Dexter2

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The channels are patched together, there is also multi-select where the dispatcher can broadcast on multiple channels at one time
the Dispatcher generally controls both Patching and Multi-Select think of Patching as a two way route of 2 talkgroups merged together by the dispatcher, whoever has one of the patched talkgroups selected can talk and hear whatever is going on on the other talkgroup.
Multi-Select is one way for use when dispatching a call or letting all channels selected know something important is going on
Thank you.
 

Dexter2

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For P25 systems, is there a reason why I can't hear or pick them up with a Squelch higher than 1?
 

jonwienke

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Generally that's because of weak signal. what is your RSSI?
 

Dexter2

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Between -40 and -55 and when I increase the squelch those numbers skyrocket, and when I try to listen to an conventional analog frequency it doesn't work when I have the squelch at 1.
 

jonwienke

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Squelch shouldn't have any effect on RSSI. It changes the signal level above background noise the scanner needs to stop scanning. Normal squelch range is 2-5.
 

Dexter2

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The NOISE level also raises very high. I'm not sure but when I raise the squelch, the talkgroups blink with no voice when something gets picked up, then if I set it back to 1 it comes in clear and the RSSI and NOISE both lower.
 

jonwienke

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The NOISE level also raises very high. I'm not sure but when I raise the squelch, the talkgroups blink with no voice when something gets picked up, then if I set it back to 1 it comes in clear and the RSSI and NOISE both lower.
Double check that by holding on a site. Squelch shouldn't have any effect on noise level.
 

Dexter2

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What is your RSSI level?
Right now its -45dBm, then randomly it blinks. When I have squelch on 1 - NOISE is 100's-400's, I just raised squelch to 3 and NOISE is now 1000-5000's, same RSSI -45. I'm picking up one talkgroup but it keeps blinking as if its not fully picking up.
 
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