SDS 100 just awful with UHF / VHF analog, static, scratchy. bad

wheels1911

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trying to listen to frequencies in the low 100.000 - 180.000 range just sound SO BAD.

Constant static, unable to make out what people are saying. Can hear voices.

Any ideas? I hear the BCD436HP is better thinking about downgrading
 

GlobalNorth

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What antenna are you using? Where are you trying to listen - car, single family home, apt, outside, etc.? Air band? FMN public safety?
 

wheels1911

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Diamond antenna RH77CA (Was told it should help, they lied)

Im in a single floor home scanner up to the window on the ledge

Air band? Idk what that means but the frequency for what I wanna hear is 154.295000MHz and its Fire-Tac
 

KE0VUL

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I've tried the RH77CA on my WS-1040, doesn't work very well on that. Not sure if it's the contact on the connector/design. Seems fine on my Icom IC-V86 though, at least for RX. If it's distant signal a yagi would probably work better, a rooftop antenna would be ideal.
 

GlobalNorth

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Diamond antenna RH77CA (Was told it should help, they lied)

Im in a single floor home scanner up to the window on the ledge

Air band? Idk what that means but the frequency for what I wanna hear is 154.295000MHz and its Fire-Tac
If you want to listen to a VHF-hi frequency, the Diamond antenna is an improvement over the stock one, but it isn't perfect.

When the radio is in the window, is it directly in line with the transmitter site and how roughly how far away is it?
 

spywiz

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Diamond antenna RH77CA (Was told it should help, they lied)

Im in a single floor home scanner up to the window on the ledge

Air band? Idk what that means but the frequency for what I wanna hear is 154.295000MHz and its Fire-Tac
Also, you may be hearing traffic from 2-3 counties away. Are you sure you are hearing local?
 

wheels1911

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If you want to listen to a VHF-hi frequency, the Diamond antenna is an improvement over the stock one, but it isn't perfect.

When the radio is in the window, is it directly in line with the transmitter site and how roughly how far away is it?
Radio is pointed up of course sitting on its butt, However the window points towards one of the Communication centers about 18 miles away, and then there is a separate one about 30 miles away. However, im quite sure the far one has repeaters because I can hear them better than the 18 mile one


And yes I am listening to the correct county.
 
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n1chu

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The two Uniden scanners recommended when working VHF/UHF are the BCD325P2 and the BCD996P2. Save the BCDx36HP’s for the digital trunking on the 700-900 MHz bands and the SDS’s for the same and when there are simulcast concerns.

When Paul Opitz (RIP) was heading up the Uniden scanner line he eluded to a couple of things relating to why certain Uniden scanners played better on certain bands. He did it in a fashion that didn’t bash the BCDx36HP’s or the SDS models but the takeaway was it’s become evident these two models weren’t performing as well on VHF/UHF as previous models had. The differences were slight as all models had reached or exceeded their target points, but because the differences were noticeable, and reported to Uniden I guess Paul thought it worth mentioning.

Don’t ask me to direct you to what posts or videos he mentioned this In, I didn’t tag them. But this is the general feeling of those who have upgraded from the older BCD396’s and the BCD996’s to the BCDx36HP’s and the SDS’s.

Paul was a bit more fourth coming, not following the tight lipped official Uniden line all that closely. He stepped slightly over the line on occasion. But when he did, he did it diplomatically, not raising the ire of Uniden too much. (I suspect Uniden recognized the trust Paul was building with his customers and gave him some room to further build on that trust.)

All that being said, the BCDx36HP and SDS models do play within exceptable levels on the VHF/UHF bands. I will add “provided a proper aftermarket antenna is used” because the stock antennas play more akin to a dummy load. Broad band scanner receivers are general coverage receivers. As such, they loose something. That is why an amateur VHF/UHF transceiver with a general coverage receiver does better on those bands when receiving. But marketing a multi-band scanner receiver to receive all bands as well as a single or dual band band receiver, while possible, is an expensive proposition. (There are commercial grade radios available, used in applications such as medivac helicopters. They need to talk to ground personnel on different bands on a daily basis. But the final cost to the typical scanner user would put it out of reach.)

I run the SDS radios for 700-900 MHz and the BCD325P2/BCD996P2 for VHF/UHF. I’ve compared the radios, using the same Log Periodic antenna made by Create, listening to the same radio systems on the different bands. While not a scientific comparison, my results are as follows; All radios received what I was using for test signals on the different bands, with the SDS radios slightly lacking on the VHF/UHF bands.
 

buddrousa

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trying to listen to frequencies in the low 100.000 - 180.000 range just sound SO BAD.

Constant static, unable to make out what people are saying. Can hear voices.

Any ideas? I hear the BCD436HP is better thinking about downgrading
Do us a favor when it is receiving one of the scratchy ANALOG signals what does the RSSI meter show and the ANTENNA BAR GRAPH show?
#1 You are discribing the Uniden Cold Solder Joint Symptoms.
#2 30 Miles on the factory antenna is asking too much. 20 Miles is stretching a rubber duck.
#3 Weak ANALOG signals do have scratchy audio.
#4 Are you close to any towers 1/2 mile or less this could be the source of your interference. Have you taken the scanner away from your location to see if it works better? How about driving in a car and see how close you have to get for the 30 mile system to work.
#5 Your $1000 cellphone only works about 10 miles that is why cell towers are about 10 miles apart. Back in the day of ANALOG cell phones in cars with external antennas 20 miles was stretching it working.
 

trentbob

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Wheels... if you're willing to take the time you will find unless your radio is defective, VHF performance is excellent on the SDS series. In the beginning there were some firmware updates that corrected issues with VHF and UHF performance as Paul acknowledged the problems and responded to them. Then there were two firmware updates introducing the filters and that is why you won't see anything in the manual about them. They're widely misunderstood and applied incorrectly.

This will be a long post but it may help. You seem to be a pretty good distance from your targets but you say the 436 works.

Hold on one of the VHF frequencies you are having issues with. Pick the most active because you're going to make changes directly on the radio secondary to real-time results of RSSI and noise levels. While listening to activity toggle function 7. If that lowers your RSSI numbers and makes things clearer then leave ifx on. If it doesn't make a difference toggle It Off.

Now while sitting on the one active VHF frequency note what your RSSI number is... The lower the number the better the reception, if you are in the upper 90s or the 100s, that's not good. Then go into menu> settings> Global filters> invert then back out of the menu and listen for a bit. If it makes things better then note the RSSI number and go back into Global filters using the same method as before and try wide normal, back out and listen. Do this for invert, wide normal, wide invert and filter off. You have already tried normal filter because Global filters are set to normal by default. Do not try auto filters, they slow scanning down as they sample every filter every time and you never know what filter does the trick anyway. This process is tedious but just go through it and know your RSSI numbers and noise levels and pick the filter that works the best. Once you pick the best filter it is imperative that you go back into Global filters and return them to normal. The global filter affects every object in your radio unless you go into the site of a system or Department settings of a conventional object and permanently change the filter.

Once you have restored Global filter to normal then... go to menu> manage favorites> choose the favorites list the frequency is in> review/ edit system> pick the system the frequency is in> edit Department> pick the department the frequency is in> set filter, it will be on global by default, put it on the filter you wrote down as the best filter when you did your Global sampling. Press enter and back out of the menu. All of the conventional frequencies in that Department will now have that filter applied just to that Department.

No, unfortunately you cannot apply a filter to just one channel, it has to be applied to the Department of that channel and affects all the channels in that department so you get around that by the way you program your radio. For example, the filter you picked for one VHF Fire frequency will apply to all of the frequencies of that fire department so you group them together in the same Department so the same filter applies to all of them. Or for example, you listen to Railroad frequencies of the same Railroad. Group them together under the same Department and the filter you apply will apply to all of those railroad frequencies in that Department.

As you master filters doing it this way which is the proper way, you're going to want to put the filter indicator on your display so as to keep track. Also when you make filter changes on the radio so that you get real-time results to go by, you want to hook up to Sentinel afterwards and transfer the changes into your profile so as to keep them.

Global filters are a tool to help you to quickly find the best filter for an object. They are not meant to be changed permanently because they affect every object on the radio that you haven't manually gone in and changed. If you change Global filters to accommodate one frequency and leave it there you will find many other objects will be compromised that work best on normal filter.

As I say using this system I find VHF and UHF performance excellent on the SDS 100 and 200. The filter that works for me may not be the filter that works for you because it depends on your local RF environment. For example I live by the water and listen to many marine frequencies and they all work better on wide normal but that might not be the case for someone else.

If you are too far away from a VHF or UHF frequency nothing is going to help except a rooftop antenna. It will be scratchy with poor performance just because of the distance. Hope this help you... Bob.
 
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Ubbe

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The problem with SDS scanner are the poor receiver that are used. They are 99 cent from Alibaba and 75 cent each if you buy 10. They have a lot of internal spurioses that mix with the received signal and create lots of other frequencies that interfere and sometime blocks the received frequency. It is bad at 800MHz and worse at UHF and really bad at VHF. Enter your favorite frequency and set to analog only and set squelch to 0 and tune around in the frequency band to hear the problem.

I connected a signal generator set to a single frequency in the 800MHz band and tuned the scanners frequency in steps from that frequency and recorded the audio. The test signal can be heard at numerous frequencies. The test ended when the scanner suddenly re-booted itself.

Audio of SDS100
Some results of a SDS100 measurements

The receiver choosen are a compromise to be able to receive simulcast transmissions but it's receive performance are probably the worst of any scanner sold today. Uniden recommended it to be used only to solve the simulcast problem and use other scanners for other type of systems.
You will have to accept that a SDS scanner might not receive a signal at all times and might be blocked by interferencies from other transmitters than the one you want to receive. But for simulcast systems it is one of very few solutions available to you.

/Ubbe
 

R0am3r

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The receiver choosen are a compromise to be able to receive simulcast transmissions but it's receive performance are probably the worst of any scanner sold today. Uniden recommended it to be used only to solve the simulcast problem and use other scanners for other type of systems.
/Ubbe
I have previously owned the BCD536HP and currently own both of the SDS series scanners (SDS100 & SDS200). My reception is essentially the same for all of these receivers while monitoring analog transmissions. The big difference is certainly the reception of simulcast transmissions. This is where the SDS scanners shine. With the proper antenna, my SDS scanners can hear VHF and UHF transmissions from my own county as well as four Upstate NY surrounding counties.

So when exactly did Uniden recommend the SDS series scanners be used only to solve the simulcast problems? Maybe I missed that marketing pitch.

Ubbe - just wondering if you actually own a Uniden SDS scanner? I own two SDS scanners and they work quite well for me.
 
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sonm10

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The problem with SDS scanner are the poor receiver that are used. They are 99 cent from Alibaba and 75 cent each if you buy 10. They have a lot of internal spurioses that mix with the received signal and create lots of other frequencies that interfere and sometime blocks the received frequency. It is bad at 800MHz and worse at UHF and really bad at VHF. Enter your favorite frequency and set to analog only and set squelch to 0 and tune around in the frequency band to hear the problem.

I connected a signal generator set to a single frequency in the 800MHz band and tuned the scanners frequency in steps from that frequency and recorded the audio. The test signal can be heard at numerous frequencies. The test ended when the scanner suddenly re-booted itself.

Audio of SDS100
Some results of a SDS100 measurements

The receiver choosen are a compromise to be able to receive simulcast transmissions but it's receive performance are probably the worst of any scanner sold today. Uniden recommended it to be used only to solve the simulcast problem and use other scanners for other type of systems.
You will have to accept that a SDS scanner might not receive a signal at all times and might be blocked by interferencies from other transmitters than the one you want to receive. But for simulcast systems it is one of very few solutions available to you.

/Ubbe
I lurk around on this forums and have seen you mention this before - what would be a better receiver chip for simulcast and receiver performance?
 

TailGator911

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I have both model SDS-series scanners and my vhf/uhf reception on both of them equal my 536/1065/ reception. This has been discussed and beat to death in here - do a simple search for SDS vhf reception and you will have something to read all day. As previously mentioned, the filter system for the SDS scanners is very unique and individualistic per each user's attributes. Depending on your location, distance to target, antenna (& height), geographic limitations, etc., your filters have to be dialed in and tweeked for optimum performance. Similar to fine tuning a shortwave radio frequency on an Icom using and blending Pass Band Tuning, a preamp, notch/noise reduction, etc. The technology is there, the only thing needed is patience.
 

radio3353

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I lurk around on this forums and have seen you mention this before - what would be a better receiver chip for simulcast and receiver performance?
FPGA (Field Programmable Gate Array) and DSP technologies are the "better" choice than what Ubbe mentioned are in the SDS radios.
 

cwhill

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I thought my head was going to explode when I first started reading up on the filters. So I rolled up my sleeves did more reading and took some time and put some testing in as described by trentbob and found my sds100 did very well on my 155 MHz frequencies where I live. I’m in Upper NY and there really is only two major frequencies I listen to that cover almost everything in my two counties. A P25 850 MHz simulcast system in one and a VHF 155 MHz in the other. I got the SDS to perform exceptionally well IMHO using the filters for the VHF. I have a BC125 that I used on the VHF system and when I have both radios going the SDS keeps pace with the 125 on VHF AFTER I got the filters set. Before the filters the SDS was missing lots of transmissions. As others have said this is very subjective to location and antennas. You definitely have to experiment ....but hey it’s a great hobby and I like to fiddle with my tech toys.
 
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