SDS100/SDS200: Why are transmissions going digital and unrecognizable after a short time..

[chad_96]

Hello all,

I have noticed an issue whether it be signal or something I'm not understanding. When scanning and listening to radio traffic, transmissions will go "digital" and aren't understandable after about 5 seconds of talking.

So, what I have noticed is the worst of it happens to radio transmissions from my local fire/ems, which is within 5 miles of me. Transmissions from further away and a farther site don't seem to be an issue. Just the local site and department. And this is happening on just about every radio transmission.

I recently added a remtronix 820S antenna to help maintain a good signal, but I honestly don't know i fit did it before the addition of the antenna. I am lost as to if there are any settings or anything I should try, or what to do to try, honestly. Just seems like further away site/departments don't have the issue as the local site/departments.

Any help would be greatly appreciated. Thanks!

 

[Whiskey3JMC]

Some

So, what I have noticed is the worst of it happens to radio transmissions from my local fire/ems, which is within 5 miles of me.

Transmissions from further away and a farther site don't seem to be an issue. Just the local site and department.

...And said "local site and department" is? Need some context of who you're listening to in order to get eyes on the database. Is said department analog conventional? Could they be mixed mode analog/P25 or something else? Could it be digital intermod from another station on the same frequency? Details are important when asking for help.

 

[hazrat8990]

I have a similar issue with my local Fire/EMS TG on P25 due to it being simulcast on the analog fire repeater. The analog channel is 154.445MHz and is sits between a couple of the traffic channels for the statewide system. Normal traffic on that TG tends to cause issues with all of my scanners and SDR's some of the time, but when dispatch sends out a page, it overloads everything. The only receiver I have that isn't affected by this phenomenon is my Unication G5.

Normal traffic on Fire/EMS:


Paging on Fire/EMS:

 

[chad_96]

Some


...And said "local site and department" is? Need some context of who you're listening to in order to get eyes on the database. Is said department analog conventional? Could they be mixed mode analog/P25 or something else? Could it be digital intermod from another station on the same frequency? Details are important when asking for help.

The site is the Arkansas Valley Correctional Facility. The departments are the bent county ambulance service, and the las animas fire department. They operate on p25 - Colorado DTRS.

I'm not sure of much of the technical aspects, as I'm new to this stuff. I just know that I also heard a Colorado State Trooper who was in town a few nights ago also had his happen during his transmissions. It seems to only have the issues of the transmissions going digital from very close by. Some of the troopers and other agencies I listen to 15+ miles away hardly have I ever noticed have had their transmissions go digital.

I guess I'm just curious if the signal from adding the Remtronix 820S is pulling such a strong signal, that it's causing this issue? Or of this is something that can happen from a more nearby site and departments and has been noted and a possible "fix" to any adjustments.

Thanks

 

[chad_96]

I have a similar issue with my local Fire/EMS TG on P25 due to it being simulcast on the analog fire repeater. The analog channel is 154.445MHz and is sits between a couple of the traffic channels for the statewide system. Normal traffic on that TG tends to cause issues with all of my scanners and SDR's some of the time, but when dispatch sends out a page, it overloads everything. The only receiver I have that isn't affected by this phenomenon is my Unication G5.

Normal traffic on Fire/EMS:
View attachment 165115

Paging on Fire/EMS:
View attachment 165116

Thanks for the reply,

I'm new to all this, so I don't exactly know what you mean by pretty much all of that.

I just know that when my local fire or ems is paged out I don't have issues. It's the radio traffic from the units. It also happened with a state trooper who was on a traffic stop inside our town. That's uncommon as I haven't had the issue with troopers transmissions doing that unless they are within the town area.

I added a remtronix 820S aftermarket antenna to boost the signal and try and make sure of a good signal, and it just makes me wonder if the antenna can have caused the signal to be so strong that it's causing issues. The site is about 10 miles from me and the town (very small) sits about about 5 miles from the site.

Other than that, I'm lost..

 

[chad_96]

So, I've tried researching through out the forums the best I can, to no avail. I don't know what it's technically called when someone is talking and their voice becomes "digital" or "scrambled". That may be part of why I'm not seeing much help.

But to clarify, I don't seem to have much issue with any transmissions further away from my area. By that I mean Site/department TG's. Therefore, just seems to be more so like it is a signal strength issue, which I may be completely wrong about also.

One thing I've considered is that maybe my sds100 is having this issue based solely on the area of my house I have it located, and it's really an issue with the signal it's receiving, and that's it. But, I don't seem to have an issue with the further away transmissions, just occasionally here and there. Just seems very odd to only be anyone within 10 miles transmissions going "digital".

Hope this description can be of some helpful understanding, if anyone could possibly help with any remedies or otherwise. Maybe I should try the stock antenna and see if it is simply that? I'm just lost and baffled..

Thanks for any help.

 

[wtp]

i would put the old antenna back on to see if that helps.
and if it does not, you might try the attenuation function.
also try moving the radio around the house to see if that changes anything.

 

[buddrousa]

Does this happen in the house only or with the SDS100 outside the house or even away from the house in town.

 

[chad_96]

i would put the old antenna back on to see if that helps.
and if it does not, you might try the attenuation function.
also try moving the radio around the house to see if that changes anything.

I will give that a try to see if it is still the same. Problem is, I live in a very small town and the local radio transmissions from my fire/ems can sometimes go days without any talk happening.

Just out of curiosity, if you happen to know, even if the signal shows full on the display, could moving the scanner around in the house help possibly clear up the transmisson issue possibly? That's something I have pondered, even with a full signal displayed?

 

[chad_96]

Does this happen in the house only or with the SDS100 outside the house or even away from the house in town.

Honestly, I haven't had the sds100 outside or away from the house out and about anywhere as I haven't had it long.

One thing I mentioned in another reply to this post was my curiosity that even if the signal showed full or minus 1 bar, could it still be where I have the scanner positioned In the house? It just seems odd thinking that as still, I am only having the issue with any transmissions within 5-10 miles. Any transmissions over 10 miles away I'm not having an issue with, usually. It does happen, just not too often.

I should clarify also, the transmissions within 10 miles are going off my closest local site. All the other transmissions are off the 2nd site in the county next to me, about 20 miles away for the site, and the state patrol units can be up to 40 miles away, and depends which site they use, but usually the further away site in the next county.

 

[Ubbe]

They operate on p25 - Colorado DTRS.

Some of the troopers and other agencies I listen to 15+ miles away hardly have I ever noticed have had their transmissions go digital.

When you monitor the local stuff and the more distant stuff, are that done using the same site in that DTRS system or is it different sites or even different systems?

If it is different sites or systems then for the site that goes digital you can try different filter settings, the Normal, Invert and so on that you can set per site. SDS scanners are prone to get interfered from other frequencies and could then distort the datasignal so it can't be decoded.
Different filter settings can change from what frequencies the receiver are interfered.

/Ubbe

 

[buddrousa]

You could be suffering from some type of interference in the house below are just a few things that could cause you problems.
1. Internet Router
2. Wifi devices (Smart TV, Smart Refrigerator, Smart Thermostat, ECT)
3. LED Lights
4. Wireless Utility Meters
5. Wireless HDMI Extender

 

[dave3825]

I have a similar issue

Your noise floor is way to high. How much gain do you have applied?



Should be low like this.

 

[hazrat8990]

The noise floor looks exactly like that normally with the gain set at 15 or 17 on the Airspy. Like I stated in my post, It only happens when there's traffic on the Fire/EMS TG, which is also blasting out over the old analog repeater. When dispatch sends out the tones, it overloads everything to the point that it even knocks out the control channels and even causes my scanners to hang on the TG without passing audio.

Kinda makes me wonder if the county has a dirty old Baofeng hooked up to an amplifier

 

[dave3825]

The pick I posted is with an Airspy set at 17 using a discone. If it works it works but that noise floor is rather high. What antenna and what and how much coax is being used?

 

[wtp]

we have a 100 sitting in a window.
it works great at about 99% of the time, but at rare times it does what you have said.
it is too fast to see if it is/was encrypted.
i know the radio should be silent on encryption, but it lasts what could be just a couple of words.
we have law dispatch and tac groups in.
so it might make sense that they want to cover only a little of a conversation.
the wife's cell phone almost sits on top of the radio, who knows, it could have something to do with it.
so yes, move stuff around.

 

[chad_96]

When you monitor the local stuff and the more distant stuff, are that done using the same site in that DTRS system or is it different sites or even different systems?

If it is different sites or systems then for the site that goes digital you can try different filter settings, the Normal, Invert and so on that you can set per site. SDS scanners are prone to get interfered from other frequencies and could then distort the datasignal so it can't be decoded.
Different filter settings can change from what frequencies the receiver are interfered.

/Ubbe

So I unfortunately am monitoring 2 sites. I monitor a site in the neighboring County that is what I am getting the state patrol traffic on, as well as the sheriff's office in that neighboring county as well. That site I have had very little issue with going digital ( I've heard it a couple times after very long transmissions)

The only site I am noticing this behavior on is my local site and happens on both the fire departments TG's for both dispatch and Tac, and also happens on the EMS Dispatch channel.

No issues with the second site or TG's for that county's sheriff's office or state patrol like the local site a d departments I mentioned above.

I show that both sites have DATA and good signal ( full signal for local site with the issues/ 1 bar less for neighboring site). That was what led me to be curious as to why it only happens with the departments within the 10 miles, as that's the only TG's that do that.

Although I'm showing full signal for the local site I wondered the possibility that the placement of the scanner in my home could still cause this issue, but other TG's again don't have that problem. Also, wondered if the REM 820S was just causing such a strong signal that it was basically overloaded the signal to the point it causes the digital transmissons to occur after the 5 seconds.

Not sure about any filters nor how to use them, but would just need to use them pertaining to the 1 site and 2 departments (occasionally 3 if csp is within 10 miles of town). They are all on the Colorado DTRS system also.

 

[chad_96]

we have a 100 sitting in a window.
it works great at about 99% of the time, but at rare times it does what you have said.
it is too fast to see if it is/was encrypted.
i know the radio should be silent on encryption, but it lasts what could be just a couple of words.
we have law dispatch and tac groups in.
so it might make sense that they want to cover only a little of a conversation.
the wife's cell phone almost sits on top of the radio, who knows, it could have something to do with it.
so yes, move stuff around.

Thanks for the reply.

I have considered the encryption possibility, but no the channels I have to monitor (fire/ems/state patrol) are not encrypted.

My scanner sits on a desk below a smart tv/wifi enabled, so could be a problem, but again, only notice it on local TG's.

The hard thing is it's a small town and those TG's are silent the majority of the time, so experimenting with moving it around can be a stale mate most of the time, but I'm working on a plan to try different locations.

Just a bummer when you try to monitor local things and you get very little of it before going digital, but further away transmissions are golden, minus the user's talking far away from the mic or swallowing thr mic.

Anyways, thanks for the advice and reply!

 

[chad_96]

You could be suffering from some type of interference in the house below are just a few things that could cause you problems.
1. Internet Router
2. Wifi devices (Smart TV, Smart Refrigerator, Smart Thermostat, ECT)
3. LED Lights
4. Wireless Utility Meters
5. Wireless HDMI Extender

Thanks for the reply,

I do have the radio and external speaker setup on a desk below a wifi enabled TV. So, maybe it could be causing interference with it.

The only mind baffling thing about that is, again, it only happens to units transmitting within 10 miles, obviously using the local and closer site to me out of the 2 sites I monitor. The further site and units 10+ miles away dont have any issues. Could that still be an issue considering that? That's what I'm curious about..

 

[hazrat8990]

The pick I posted is with an Airspy set at 17 using a discone. If it works it works but that noise floor is rather high. What antenna and what and how much coax is being used?

My noise floor is identical to yours unless there's traffic on that specific TG and then it turns into the mess you see in my screenshots. Antenna type and coax has absolutely nothing to do with the dirty signal that's being splattered when the analog repeater starts transmitting.