BCD436HP/BCD536HP: BCD436HP - The Sensitivity "test" (it had to come out eventually..)

[k3fs]

My 436 sensitivity is particularly bad on VHF using a duck. I have used many different duck antennas. I have to use the Diamond antenna to get comparable performance that I am getting using a no name small antenna on the 396XT. The 396XT still receives better. I tried the same antenna on the 436, and it was really bad. So, I use the Diamond on the 436 all of the time. I would like to use a smaller antenna, but that just does not work well enough.

That being said, the oddities are that I can pick up some trunking systems better. Of course I am not using a really good antenna on the 396Xt, but the 436 does pick up well on 800mhz for me.

Now plug the 436 into an outside antenna, and the thing shines. It does significantly better than the 396XT on the same antenna. VHF performance on the outside antenna is very good. I could never figure out why this would be. But, reading about the noise generated by the radio in VHF range may explain this. Especially when using a duck.

 

[bearcat7039]

We've heard anecdotal reports about questionable VHF performance on Uniden's 'Flagship' handheld scanner on this forum over the last nine months or so. I thought it was about time we finally nailed some sensitivity figures down and found out what is really going on here.

The following tests were conducted with a calibrated HP service monitor using a high quality RG-400 coax patch lead. The received audio was taken from the headphone socket in each case via the same audio line isolation transformer. All tests were conducted in NFM mode at 1.5Khz deviation. I should mention that my BCD396XT has had the 450Khz IF filter changed to the narrower 'G' version, which should closely mimic the filter characteristics in the BCD436HP in NFM mode. Regardless, the filter change in the BCD396XT would not impact greatly on the observed figures in these tests.

Caveat:

There are obviously slight variations in performance from model to model and even within the same batch of the same model.
The following results may have been impacted slightly by these variations. The results I obtained may be different to results others obtain.
Regardless, I am confident that in my case at least, there is a significant difference in sensitivity between my two units.

There are two fields in this test.
The first field measured sensitivity in dBm, the second in uV.
The dBm measurement is this case is more accurate, however the uV tests have been included so that you can compare the measured figures with Uniden's claimed specifications.

Comments and observations:

Firstly, it was immediately obvious that my BCD436HP does have some serious sensitivity 'deficiencies' on some bands. The 163Mhz, 420Mhz and 820Mhz bands were all 2-3dBm down in sensitivity compared to the older BCD396XT. Looking at the uV figures, my BCD436HP doesn't even meet Uniden's own specified 0.3uV level. This is very poor form IMHO.

During these tests, My BCD436HP only met the specified 0.3uV sensitivity on bands below 146Mhz.
It was interesting that the BCD436HP actually outperformed the BCD396XT on the 53Mhz (6M) band.
Another issue I have confirmed, is that the BCD436HP does in fact radiate some low level, broadband noise on the VHF bands. The noise is radiated from the vicinity of the LCD. I believe that the noise is likely produced by an internal CPU or associated system. This noise appears to degrade VHF reception slightly when using the supplied stubby antenna, or any other handheld antenna and results in weak signals not opening the squelch, even at it's lowest setting of 2..

So there you go.. For what it's worth, my results of sensitivity testing on my two Uniden scanners.

And, while these tests were conducted in NFM mode, sensitivity figures also effect weak signal digital performance too. Yes, the BCD436HP sounds great on P25, but the fact is that if you want optimum weak signal performance, it's pretty hard to beat the humble little BCD396XT.

As always, YMMV, but personally, I am a little disappointed in the RF performance of my BCD436HP.

It's a digital scanner made primarily for digital reception. If you want VHF save yourself some money and buy a non digital scanner. My BCD436hp does fine on the local VHF/UHF freq I want to hear....

 

[joeuser]

Exactly, clearly it's impossible to make a scanner that just does great across the board (maybe it's a money thing). So that being the case, I use my older rigs for what they excelled at VHF/UHF <512 & my newer radios on TRS. It seems the only radio I own that does great on everything is my GRE PSR 800. When I team that up with my CenterFire antenna - wow... Especially the last 16 hours with this skip, ducting, whatever I'm getting here in KS - it's working to well - giving me a headache!

 

[Boatanchor]

Interesting results...

Aeroflex 3920 (last cal was June of 2014) using a Stanford Research Systems Rubidium Frequency Standard.

1 KHz tone at 1.5 KHz deviation for 12 dB SINAD

151.0025 -119.4 dBm .240 uV
155.0250 -120.0 dBm .224 uV
171.0000 -120.7 dBm .204 uV

453.0000 -119.3 dBm .242 uV
460.0000 -119.6 dBm .234 uV
465.0000 -119.6 dBm .234 uV

770.0000 -117.8 dBm .323 uV
851.0000 -116.6 dBm .331 uV
860.0000 -116.6 dBm .331 uV

Now if this isn't confusing I don't know what is. My results may explain why I don't see the sensitivity issues that others see.

I didn't perform any tests for internal noise, but I'd be willing to bet it's present.

And not to get nit-picky, but if the Uniden spec is .3 uV (and not .300 uV) then your radios meet this spec in all but one test (820.5 MHz).as anything from .3 to .399 would be within spec...but I'm not here to argue.

Thanks for pointing that out Kevin.

Those figures actually don't look too different from mine. The difference is that the few frequencies you chose to test on do not correspond to the 'dips' in sensitivity that were depicted in my table/graph here:

http://forums.radioreference.com/un...st-had-come-out-eventually-5.html#post2264697

Also, it is odd that you say that the figures all meet specification apart from 820.5Mhz, yet you failed to test those bands which were evident as problem areas in my unit. In other words 160-163Mhz and 500-520Mhz.

Personally, I don't care about the sensitivity levels above 500Mhz as I don't have any systems nearby that operate on those frequencies.

The other related issue that I did highlight early on was the operation of the BCD436HP squelch. It effectively adds another 3-4dB to the base sensitivity levels. In other words, on my unit the squelch (on the lowest setting of 2) will not open until the signal/carrier is 3-4dBm higher than the measured 12dB Sinad point. By contrast, my 396xt's squelch at the lowest closed levels, will open well below the 12dB Sinad point.

Putting this another way, if the BCD436HP sensitivity on 510Mhz is -116dBm, the squelch won't open until the carrier level is -112 to -113dBm or around 0.56uV. Which kind of makes the Sinad sensitivity tests under 'real world conditions' a moot point.

I believe the squelch tables were adjusted by Uniden in one of the few firmware updates. It was probably done in an effort to improve scanning speed but it did have a negative impact on weak signal performance.

 

[SOFA_KING]

If you actually take the time to look at my test results, you will see that:

1/ The graphs only depict the measured sensitivity figures obtained from my BCD396XT and my BCD436HP. I also pointed out that there would be minor production variations between units.

2/ No GRE derived scanners were tested at the time.

3/ My BCD436HP met or exceeded the manufacturers specified sensitivity of 0.3uV or -117dBm (@ FM 12dB sinad) on every band but the 510Mhz band, where the sensitivity did seem low and did not meet the specified level. The 160Mhz band was the other band where sensitivity did seem a little 'down' compared to my BCD396XT, however despite this, the scanner still met the specified 0.3uV sensitivity level (just).

4/ Unless you are interested in receiving extremely weak/distant signals, as I am, it is unlikely that you will notice a difference of 1 or 2dBm in sensitivity. But with P25 in particular, a 2 or 3dBm difference in sensitivity can make a huge difference in decode BER performance of weak signals. Sometimes to the point where signals are either decoded or not.

5/ I have asked that others, owning appropriate test gear, contribute to this thread with their own test results to compare with my results, but sadly to date, nobody has. It is a little strange that considering the number of scanners that are out there, so little independent testing is actually done.

And

6/ Sensitivity is only one factor at play here. There are many other aspects such as IP3, receiver blocking, selectivity, digital decoder performance, audio filtering, squelch operation etc etc etc and they all impact on how well a scanner works

Thank you for doing the test. I do appreciate it. I never owned the 396XT or 996XT, so I have no reference there...just the GRE/Whistler scanners. But I do believe the manual P25 adjustment and ceramic NFM filter does wonders on the x36 scanners for digital decode. It would be interesting to see a P25 sensitivity test done. If I still had access to that type of service monitor, I'd do the testing. But that was two lives ago.

Phil

 

[KevinC]

Thank you for doing the test. I do appreciate it. I never owned the 396XT or 996XT, so I have no reference there...just the GRE/Whistler scanners. But I do believe the manual P25 adjustment and ceramic NFM filter does wonders on the x36 scanners for digital decode. It would be interesting to see a P25 sensitivity test done. If I still had access to that type of service monitor, I'd do the testing. But that was two lives ago.

Phil

Just curious, how would you determine the BER of the scanner? Do you know the keystrokes to show this? If so I'd be happy to do a BER test on P25 Phase 1 and 2.

 

[SOFA_KING]

My 436 sensitivity is particularly bad on VHF using a duck. I have used many different duck antennas. I have to use the Diamond antenna to get comparable performance that I am getting using a no name small antenna on the 396XT. The 396XT still receives better. I tried the same antenna on the 436, and it was really bad. So, I use the Diamond on the 436 all of the time. I would like to use a smaller antenna, but that just does not work well enough.

That being said, the oddities are that I can pick up some trunking systems better. Of course I am not using a really good antenna on the 396Xt, but the 436 does pick up well on 800mhz for me.

Now plug the 436 into an outside antenna, and the thing shines. It does significantly better than the 396XT on the same antenna. VHF performance on the outside antenna is very good. I could never figure out why this would be. But, reading about the noise generated by the radio in VHF range may explain this. Especially when using a duck.

I also noticed the noise problem using portable antennas on my 436. The VHF range is limited by it. I use a Comet SMA-24 to improve range. And yes, squelch action has an impact, as well. Nothing of this caliber is perfect in all aspects. I wish it were. You do the best you can. But in base and mobile use, my 436 does better than any scanner I have owned (sorry, no 396/996 to compare here).

Phil

 

[SOFA_KING]

Just curious, how would you determine the BER of the scanner? Do you know the keystrokes to show this? If so I'd be happy to do a BER test on P25 Phase 1 and 2.

I can't speak for a 396/996 (I'm sure others can), but on a 436 you can see the error rate by programming a VHF channel in a favorite list for NFM MANUAL 9, and then holding on that channel. While holding, press down on the volume knob, press the side function button, and then again press down on the volume knob. The ERR: rate will display at the bottom of the screen.

On the 536 you press function and then in on the volume knob to call up the ERR: display. I would not test with AUTO. It will drift all over the place on weak signal. I found MAN 9 to be the best value on all federal systems I listen to. I assume they have proper deviation adjustments. Does ERR equal BER? I can't say, but at least it is giving some error rate value indication.

Thanks for testing this! I will be elated to see the results.

Phil

 

[KevinC]

I can't speak for a 396/996 (I'm sure others can), but on a 436 you can see the error rate by programming a VHF channel in a favorite list for NFM MANUAL 9, and then holding on that channel. While holding, press down on the volume knob, press the side function button, and then again press down on the volume knob. The ERR: rate will display at the bottom of the screen.

On the 536 you press function and then in on the volume knob to call up the ERR: display. I would not test with AUTO. It will drift all over the place on weak signal. I found MAN 9 to be the best value on all federal systems I listen to. I assume they have proper deviation adjustments. Does ERR equal BER? I can't say, but at least it is giving some error rate value indication.

Thanks for testing this! I will be elated to see the results.

Phil

Yeah, I'm not sure what the "ERR" means. I'm quite sure it isn't BER since it can go to 30 or more and still receive. On real radios a BER of 30% would result in no receive.

I'm not sure using that would be useful since we don't know what it represents.

 

[SOFA_KING]

Yeah, I'm not sure what the "ERR" means. I'm quite sure it isn't BER since it can go to 30 or more and still receive. On real radios a BER of 30% would result in no receive.

I'm not sure using that would be useful since we don't know what it represents.

Agreed. But maybe comparing both radios with this display showing might show some value that would indicate which radio decodes with fewer errors given a fixed signal level. ???

P

 

[Boatanchor]

Agreed. But maybe comparing both radios with this display showing might show some value that would indicate which radio decodes with fewer errors given a fixed signal level. ???

P

Yes, there may not be any published relationship between the Uniden 'Err' rate and the industry accepted BER, but it may still give enough feedback to provide a valid comparison between models.

You could set the aeroflex 3920 up to generate a standard P25 test signal and reduce the generate level until you obtain an displayed 'Err' rate of say 10 or something. You would have to be careful to use the manual decoder settings in the scanner though. In my experience, the Auto (decode level) function doesn't work at all at low signal strengths. Personally, I would use the fixed level of 8 as this seems to give the best low signal strength P25 decode error rates.

Also, ideally the test would have to be done on multiple frequencies, even within the same band as it appears that the 436HP sensitivity may not be quite as uniform as the x36 line.

The results would be very interesting

 

[joeuser]

Maybe it was just a typo on BEER?

 

[stingray327]

I also noticed the noise problem using portable antennas on my 436. The VHF range is limited by it. I use a Comet SMA-24 to improve range. And yes, squelch action has an impact, as well. Nothing of this caliber is perfect in all aspects. I wish it were. You do the best you can. But in base and mobile use, my 436 does better than any scanner I have owned (sorry, no 396/996 to compare here).

Phil

mY 436 in car picks up alot of static or interferance on marine band and OES channels.

 

[SOFA_KING]

mY 436 in car picks up alot of static or interferance on marine band and OES channels.

Could it be your car? Old fashioned ignition noise, maybe? Fuel pump noise, perhaps?

When I do open searches while traveling around, I'm always amazed by the signals other vehicles emit. Some are so bad that they can be jamming me from many car lengths away. And some can jam many frequencies. Even my own SUV has a couple of birdies I have to temporarily lockout. Then there are gas stations and even residential habitats that emit trash. One I got today on low band sounded just like the old CRT TV sets of the 70's and was picked up for at least three tenths of a mile. It's a wasteland out there in RF land. Trash everywhere. Then there is power line noise, although usually reduced on VHF high band, it can still be a problem at times. But you can't blame the scanner for any of that. The FCC? Yes, you can blame them.

Phil

 

[stingray327]

Could it be your car? Old fashioned ignition noise, maybe? Fuel pump noise, perhaps?

When I do open searches while traveling around, I'm always amazed by the signals other vehicles emit. Some are so bad that they can be jamming me from many car lengths away. And some can jam many frequencies. Even my own SUV has a couple of birdies I have to temporarily lockout. Then there are gas stations and even residential habitats that emit trash. One I got today on low band sounded just like the old CRT TV sets of the 70's and was picked up for at least three tenths of a mile. It's a wasteland out there in RF land. Trash everywhere. Then there is power line noise, although usually reduced on VHF high band, it can still be a problem at times. But you can't blame the scanner for any of that. The FCC? Yes, you can blame them.

Phil

I have two different cars and it happens in both of them. I usually just end up hitting the "avoid" button for temporary blocking.

 

[sibbley]

If I use the stereo in my 07 Accord I get terrible interference on most of my scanners. Stereo turned off, NO interference. Heck, I even get the interference on my HT1250 and my F60v. Oh, and that is NOT connected to the vehicle power source. Just on the unit's own batteries.

My 99 Blazer I have NO such issue. In the Accord with an external antenna, NO problem. Electronics today, sheesh...

 

[ratboy]

I've noticed recently that both my base scanners (Pro-197 and ancient BC-760XLT) have begun to be sometimes trashed on many VHF frequencies when my 40" Toshiba TV is on. I have played around and it's being caused by the backlight being on or off. If I go into the settings and turn the brightness down to nothing, the hash is gone, but returns at low level as soon as I increase it. I would imagine this is coming from the inverter that powers the CCFL. I don't want to buy another TV right now, so I'm tolerating it by locking out most of the air band freqs where the problem is the worst. Both these radios are on external antennas. My handhelds, all of them, seem immune to this issue. I guess maybe the hash is coming in through the 12V power supply that runs both the base radios somehow. I guess I'll have to try running them on the jump box I have in my car and see what happens. That PS is like 30 years old now..

 

[sibbley]

I think today's scanner are simply prone to interference. I have my original Regency HX1500 that has never had interference issues. However, if the HX1500 is sitting within 3 feet of the 436HP, the 436 picks up interference from the HX1500. If I move the HX1500 across the room the "noise" in the 436 goes away.

Alot of my 436HP VHF and UHF analog problems go away when I leave the Lehigh Valley. Once I get out into Berks County the scanner receives very well with a duck. It's not perfect but much better. Also, the bigger the antenna, the better.

I'm not downplaying the tests done that began this thread. The information provided most likely contributes to the problems with the 436HP. I've just come to the realization that this will continue to be a problem due to the manufacturing habits of electronics today. Cheaper parts means more "noise".

My Regency still today, receives better without an antenna than my 436HP with a duck.

 

[SOFA_KING]

External noise sources are just that...external. You can't blame the scanner for any of that. Plus, noise emissions can be wide or narrow in bandwidth. So different receivers will react differently depending on how wide the receiver selectivity is and how sensitive the receiver is.

What most people are not aware of is noise that is very wide in nature, but not breaking open the squelch. It is still degrading reception even though you don't "hear" it. To the receiver, it just looks like a high noise floor. You might see some elevated S meter readings, but a lot of noise can be destructive even below "one bar". The only way to actually know for sure what type of noise is out there, and how strong it really is, is checking the spectrum with a very sensitive spectrum analyzer. Then you can actually SEE consumer trash, cable leakage, wide band computer noise, real actual intermod, power line noise...you name it.

For those who suffer noise emissions from their own consumer garbage, there is hope you can diminish or even eliminate the problem. Clamp ferrite chokes on every lead wire or cable that goes into or out of those devices. Put the chokes as close as possible to where it enters those devices. You may be surprised at how you can eliminate the problem. And if you transmit radio signals, like ham or CB, your devices will benefit from reduced interference. Blaming the scanner will not do anything to help.

I clamp ferrite chokes on everything! Especially anything coming in or out of a computer. Even on the power leads. And I try and use GOOD shielded cables on everything...including power leads if they are available. My TV sets and home theater equipment have chokes on all leads. All networking equipment, as well. Guess what? I have zero noise coming out of my devices, and no interference issues when I transmit. I checked my house with a sensitive spectrum analyzer, and I'm totally clean. My neighbors or my cable company? Not so clean, but than it comes down to diplomacy. If they will allow you to install chokes, you can usually fix their stuff too. The cable company? First you have to be 100% able to prove it is them, then present the evidence and wait for them to check the area and fix it. If they don't (which is rare), threaten you will report them to the Cable Commission or FCC for violating cable leakage laws. The power companies also have leakage laws, but are often lax on maintaining acceptable levels. But the point is that YOU CAN do something about most noise and interference issues if you take the initiative.

Phil

 

[AA6IO]

My 396XT still outperforms my 436HP and even my 325P2 with the stock antenna indoors in terms of opening up squelch on signals that the other two don't, or in some cases, do not even hear. However, I can hear noise in both the 436HP and 325P2 in these circumstances while the 396XT is quieter. This is all subjective, no hard test data. But the 396XT certainly has the edge with marginal antennas or situations.
However, once I get out of the house with less noise, the 436HP and 325P2 begin to equal the performance of the 396XT in terms of weak signal performance. As I go to better antennas like the RH77CA, the difference is less, and things sound more equal in terms of weak signal performance.
Once I put on something like a mag mount on these handhelds, then the 436HP begins to shine and performs better, followed equally by the 325P2 and 396XT. Like others, once a bigger antenna is hooked up to the handhelds, the 436HP performs more like my 536HPs. Interestingly, my 536HPs do as well as the 996XT on weak signals, even with stock antennas, But that's not true for the 436HP.
Just basically experiencing what others seem to be describing, namely, some inherent noise in the 436HP. I believe Boatanchor commented on this a while back, but it probably is also something to do with how the squelch is set to go off. I just have the gut feeling (no hard test data) that the 396XT opens up maybe 2 to 3 dBM lower than do the newer Uniden models. Maybe this is the way they are designed.
For those listening to stronger signals, it doesn't matter, but I am always kind of a DX nut and try to hear weaker stuff. My older scanners and radios like my IC-51A and IC-R20 just do better on weak signal analog. Now if only those radios had digital and trunking.
Maybe it's the old NFL (no free lunch) principle. There is no question that my 436HP is the best performer up at 800 Mhz even with minimal antennas, even a paper clip. I can use a paper clip on the 436HP and get 470 Mhz trunking sites with decent P25 decode. But down low, it another story.