Will a dedicated DSP speaker help SDS200 audio?

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mortoma61

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I live in central Utah ( non-encrypted scanner paradise ) and I just got a new Uniden SDS200 scanner about a month ago. One problem I have with listening to local stuff is the 'listener fatigue" I get from weaker signals that pop in and out of background static all the time. The incessant KKKK-kkkk-KKKK static noise can be annoying to listen to when you get a police unit that comes in weaker than the dispatch ( just an example ). All of that makes it a bit stressful and difficult to listen for long. I realize that if Uniden built in a DSP chip to help process that out it would make their scanners more expensive and possibly even bigger. My thinking is I could try a dedicated DSP speaker to feed my audio into from the back of the radio and maybe that would take some of that scratchy static out?? Ham radio operators use them for both CW and regular talk on HF. But I don't know if that would help a scanner like a Uniden that has less than stellar signal to noise ratios at VHF and UHF frequencies. Is digital signal processing of my audio output the answer to my ills? All I know is all the crackling is louder than heck compared to a good quiet signal at normal volume levels. Very irritating.
 
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ProScan

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Are you referring to the internal speaker or computer speakers? I don't hear any background hiss or crackling with volume fully up in the internal speaker. Did you update the firmware to at least 1.02.01 Sub / 1.08.05 Main (3/7/2019)? That version includes"
"Added an "AMP OFF Timer" setting that determines how long the amplifier stays on after a transmission ends. If you hear hum between transmissions, change this from Infinite to one of the available settings"

If wired to the sound device then it is due to the copper interfacing and in that case, the IP audio produces the best audio.
 

bob550

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My assumption here is that you're monitoring mostly analog signals, not digital. That said, the weaker the analog signal the noisier the audio can be. Your first priority would be to improve your incoming signal strength through the use of a better antenna mounted outside if possible. If not, a dedicated DSP unit may help quiet the noisier signals to some degree. I've had some success using a Timewave DSP on my Icom R71A on the HF bands. I don't use, or need, audio signal processing on my scanners as mostly all the stuff I listen to is digital P25.
 

mortoma61

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My assumption here is that you're monitoring mostly analog signals, not digital. That said, the weaker the analog signal the noisier the audio can be. Your first priority would be to improve your incoming signal strength through the use of a better antenna mounted outside if possible. If not, a dedicated DSP unit may help quiet the noisier signals to some degree. I've had some success using a Timewave DSP on my Icom R71A on the HF bands. I don't use, or need, audio signal processing on my scanners as mostly all the stuff I listen to is digital P25.
Thanks for the response and you are correct, the Utah Communications Authority Network (UCAN) is Motorola analog. It's listed as "Motorola Type II SmartZone Omnilink" and "Analog and APCO-25 Common Air Interface". I understand about a analog signal being noisier if it's weak but having listened to scanners going all the way back to my old Bearcat 250 I bought in 1978 and all sorts of other VHF/UHF 2 meter and 440 transceivers but I have never heard background static crackling as bad and as loud as it is on this SDS200 on weaker signals. My old AOR 1500 receiver was great in the noise quieting but it bit the dust a few years ago and it didn't have trunk tracking capability anyway. I don't really need a better antenna than the one on the back of the set because all that is between me and the entire Utah county valley is a little dry wall and siding! My room where my radio is faces the whole valley and the UCAN network allows me to get police, EMS and fire dozens of miles away. From my window I can see Spanish Fork wind turbines that are exactly 29 miles away. I'm on a side of a hill overlooking it all, plus I can get Salt Lake public service too and there are mountains in the way of that area. I think there are UCAN repeaters that help out. An outdoor antenna would help some but not enough to justify the expense and work required to install an outdoor antenna. Most of the network comes in under 120 RSSI. But sometimes there are weaker signals for the police cars and HTs they use that get the extremely loud noise. Louder than any scanner or transceiver that I have ever had. Not saying the SDS200 is a bad radio, in most respects it's excellent and I feel it was worth the price, overall. I might try a good DSP speaker I guess, the high price of them is a risk I might have to take unless the place I get one from has a return policy? Wish me luck!!
 
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mortoma61

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Are you referring to the internal speaker or computer speakers? I don't hear any background hiss or crackling with volume fully up in the internal speaker. Did you update the firmware to at least 1.02.01 Sub / 1.08.05 Main (3/7/2019)? That version includes"
"Added an "AMP OFF Timer" setting that determines how long the amplifier stays on after a transmission ends. If you hear hum between transmissions, change this from Infinite to one of the available settings"

If wired to the sound device then it is due to the copper interfacing and in that case, the IP audio produces the best audio.
No, I'm talking about connecting an external speaker to the output on the back of the set, which I presume to be at line level. A DSP speaker is not just a speaker, they have a Digital Signal Processing ( DSP ) board that can filter out a lot of stuff and leave the voice audio or whatever type of audio it might be other than voice. They are not miracle workers or anything but they can make signal more listenable. I just happen to have never used one on any radio, HAM or otherwise so I just wanted people's opinions as the whether or not they are worth it on VHF/UHF analog signals.

Thanks for the info, I'll look into the firmware update. I think I have the latest but I'll check. BTW, I don't run my audio into my PC speakers, although I could do that if I wanted. Not sure what you mean by IP audio, you did not explain that.
 

bob550

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The UCAN system appears to be 800 MHz analog. Provided you're only monitoring repeater outputs and not the input frequencies, you shouldn't have much trouble given your geographic location. It is possible, however, that the problems you are experiencing are system-related and not related to your receiving situation. For example, the mobile unit may be transmitting from a RF dead-spot and the dispatch center may be also having trouble receiving their signal. I've experienced that myself on our local 800 MHz P25 system where dispatch will ask the mobile unit for a repeat of the transmission. If dispatch didn't say anything, I'd have thought the reception problem was all mine.
 

bob550

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No, I'm talking about connecting an external speaker to the output on the back of the set, which I presume to be at line level.
You could also run the audio into the audio input on your computer, provided you have decent speakers. Your sound card may already have the software capability to greatly enhance the 200's audio without spending another nickel. I have the ability to do that with my 536, via the Wifi dongle, and the improvement in fidelity can be dramatic.
 

KE5MC

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Don't underestimate the attenuation that "Dry wall/Siding" may have. Easy test, using extension cord take the SDS200 outside and see if reception improves. What RSSI levels do the static receptions come in at? Coming in under 120 is not much help. If they are coming in 120 to 110 I call them weak signals. From your description of location I would expect better reception. DSP can help, but can't replace what is not present and will have some impact on the audio in it's effort to filter out background static. DSP powered external speakers are expensive! The most bang for the buck to improve reception/audio is usually a better antenna or antenna location. Ham use of DSP on HF is dealing with a different noise characteristic than FM weak signal noise. I admit in the case of the SDS200 the demodulation of the FM is likely different that a traditional FM hardware demodulator which I have experience with.

P.S. To address your original question of will DSP help. I don't think it will and every signal out of your scanner will be passing thru the DSP 'filter' and may have varying impact that you might not like going from good strong signals to weak ones. No black/white answer here, sorry.
 
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sparklehorse

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It's hard to know if the "incessant KKKK-kkkk-KKKK static noise" is the result of the signal being weak, or if you're what you're describing is more due to analog simulcast issues. It could be both. In either case I agree a better antenna is worth a try. I've had good luck using a cheap cell phone yagi like this one:

https://www.amazon.com/XHTECH-824-9...1549934949&sr=8-46&keywords=cell+yagi+antenna

They aren't that big, so you may be able to mount it indoors near a window. The advantage of these is they are very directional. So you can aim it at a distant tower and boost your signal a great deal. If simulcast is the issue they can help with that as well because you can focus on one tower while partially nulling out others. It takes some experimenting to find a sweet spot, but they can work wonders. Note that these are great for 700/800 MHz, but only just OK for 450 MHz UHF, and quite poor for VHF. So not a good option if VHF band is also of interest to you. You will need some decent coax and appropriate connectors. Also coax seal and lightning protection if you mount it outdoors. If you have a Ham Radio Outlet store nearby they can help you with the coax, etc. Just take the antenna and scanner in with you and ask for some help.

Also YES, update to the latest SDS firmware released just today. It may very well help. And YES, you need to try ALL the different filter settings if you haven't already. Hope that helps.
.
 
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mortoma61

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Don't underestimate the attenuation that "Dry wall/Siding" may have. Easy test, using extension cord take the SDS200 outside and see if reception improves. What RSSI levels do the static receptions come in at? Coming in under 120 is not much help. If they are coming in 120 to 110 I call them weak signals. From your description of location I would expect better reception. DSP can help, but can't replace what is not present and will have some impact on the audio in it's effort to filter out background static. DSP powered external speakers are expensive! The most bang for the buck to improve reception/audio is usually a better antenna or antenna location. Ham use of DSP on HF is dealing with a different noise characteristic than FM weak signal noise. I admit in the case of the SDS200 the demodulation of the FM is likely different that a traditional FM hardware demodulator which I have experience with.

P.S. To address your original question of will DSP help. I don't think it will and every signal out of your scanner will be passing thru the DSP 'filter' and may have varying impact that you might not like going from good strong signals to weak ones. No black/white answer here, sorry.
Thanks but really not having a reception problem as most of my signals, even at a relatively medium to poor 120 RSSI are at full quieting. Problem is the loudest static crashes on weaker signals that I have ever experienced, relative to how loud I have the volume for good signals. If the SDS200 were even half as good in this respect as my old AOR1500 I'd be tickled. I just think that Uniden could do better on S/N. If I listen to a fully quiet dispatcher at a comfortable ( not very loud, because I hate loud ) level most weaker signals can have scratchy and very loud static, much louder than the good audio received, so I end up turning the volume down, always fighting volume. Most of my signals from UCAN are well under 100 RSSI ( lower is better ) and I hear stuff reasonably well at as bad as 150 RSSI. I'd say that 90 to 95% of what I head is quiet and intelligible, just when the nasty scratches do come, they bother me. I am simply not going to put up an outdoor antenna but thanks for stopping by, all you smart techie guys/gals are always nice to hear from, appreciate it.
 
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mortoma61

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It's hard to know if the "incessant KKKK-kkkk-KKKK static noise" is the result of the signal being weak, or if you're what you're describing is more due to analog simulcast issues. It could be both. In either case I agree a better antenna is worth a try. I've had good luck using a cheap cell phone yagi like this one:

https://www.amazon.com/XHTECH-824-9...1549934949&sr=8-46&keywords=cell+yagi+antenna

They aren't that big, so you may be able to mount it indoors near a window. The advantage of these is they are very directional. So you can aim it at a distant tower and boost your signal a great deal. If simulcast is the issue they can help with that as well because you can focus on one tower while partially nulling out others. It takes some experimenting to find a sweet spot, but they can work wonders. Note that these are great for 700/800 MHz, but only just OK for 450 MHz UHF, and quite poor for VHF. So not a good option if VHF band is also of interest to you. You will need some decent coax and appropriate connectors. Also coax seal and lightning protection if you mount it outdoors. If you have a Ham Radio Outlet store nearby they can help you with the coax, etc. Just take the antenna and scanner in with you and ask for some help.

Also YES, update to the latest SDS firmware released just today. It may very well help. And YES, you need to try ALL the different filter settings if you haven't already. Hope that helps.
.
Good idea but I listen to a lot of aircraft too. Not much below that though. I used to be a pilot back in the day but it got too expensive for me by 2010. So my flying life is now hangered forever. For sure going to install the update. Just wish I didn't have to kill my router firewall temporarily to download updates.
 
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