joeuser
The Wretched
Yeah I'm interested in that result!
BCD436HP/BCD536HP: BCD436HP - The Sensitivity "test" (it had to come out eventually..)
- Thread starter Boatanchor
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scannersnstuff
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not uniden bashing, just stating my feelings. uniden imho was so eager to get the 436hp out the door before whistler hit, with the same scanners that gre produced. they just comprimised features over performance. what a huge disappointment !. i promise i will not say anything more. i'll just stick with my older unidens.
I find this very interesting. Since the first reports of bad VHF sensitivity I compared my 436 and 536 to multiple other units (BCT15, PSR-800, PSR-600, HP-1 to name a few). I have them all connected to the same antenna (R/S "Sputnik" 20-176) via a 8-port multicoupler with filters for FM broadcast and TV channels 8, 11 and 13. Using the NWS as my gauge they all receive the same number of stations (varies daily from 4-6), even the extremely weak one(s) are received at the same level (to my ear) and I never have any one radio receive a station that the others don't.
Maybe I just got lucky???
As far as sensitivity using an antenna attached to the 436 I haven't compared that, so it may very well have internally generated noise that a screw-on antenna picks up.
And I'm not doubting anyone's reception issues, I just don't see it. Maybe I'll put mine on my 3920 and see what it does.
Maybe I just got lucky???
As far as sensitivity using an antenna attached to the 436 I haven't compared that, so it may very well have internally generated noise that a screw-on antenna picks up.
And I'm not doubting anyone's reception issues, I just don't see it. Maybe I'll put mine on my 3920 and see what it does.
OK, interesting as these statistics are, what do they mean for real world monitoring? Remember we are talking about a 12 db sinad. This is a very marginal signal. That is, the signal is 12db above the noise floor. This is hardly full quieting and many people would not like to listen to signals this weak because of the noise level. How many of us monitor extremely weak signals? Yes, if you want to hear the fire department two counties over, you may listen to this kind of weak signal. However, if you just want to listen to your local police or fire department and that department uses a repeater, you won't ever need extreme sensitivity. In fact extreme sensitivity may result in interference from overloads and intermods.
So has this study exposed these new Uniden radios as frauds? One the one hand, they should meet or exceed their own published specs and, if they don't that's a problem. On the other hand, does this mean that the new scanners are as useless as a brick for serious monitoring, not hardly.
The ARRL lab tested the HP-1 in April 2011. I think this is the only test they have done of a scanner. They measured sensitivities between .2 microvolts and .32 microvolts. The lowest being at 902Mhz. Not bad at all. It seems that Uniden is not measuring up to that standard anymore (or ARRL got a specially tweaked unit).
A final thought. In the old days of crystal controlled scanners, sensitivities between .5 and 1.0 microvolts were considered very good and we listened to a lot of stuff. Also, no matter how good your radio is, you need a good antenna system and that can certainly make the difference between a few fractions of microvolts.
So has this study exposed these new Uniden radios as frauds? One the one hand, they should meet or exceed their own published specs and, if they don't that's a problem. On the other hand, does this mean that the new scanners are as useless as a brick for serious monitoring, not hardly.
The ARRL lab tested the HP-1 in April 2011. I think this is the only test they have done of a scanner. They measured sensitivities between .2 microvolts and .32 microvolts. The lowest being at 902Mhz. Not bad at all. It seems that Uniden is not measuring up to that standard anymore (or ARRL got a specially tweaked unit).
A final thought. In the old days of crystal controlled scanners, sensitivities between .5 and 1.0 microvolts were considered very good and we listened to a lot of stuff. Also, no matter how good your radio is, you need a good antenna system and that can certainly make the difference between a few fractions of microvolts.
jland138
Member
When I first saw this thread, I felt the same way: does it really matter?
After pondering about it a little more, I think it really does. 12db SINAD is pretty much the gold standard for measuring analog receiver sensitivity. You may not enjoy casual listening at this level, but you can immediately compare it to say an APX 7000 (.216 uV or -122.5 dBm on VHF, .234 uV or -119.5 dBM on UHF) and know a lot about what to expect from the receiver.
Maybe it depends on the area where you live, but weak signal behavior is still important in my area which utilizes analog mutual aid and TACs on VHF, UHF and 800MHz. It's not exactly DX, but pulling out handhelds and mobiles working searches, fires and rescues still requires a good analog receiver in my area of monitoring.
If I had quibbles with the analysis, one might be using a 1.5KHz deviation. That's the right number for narrow band FM of course. But, given the post UPMan made in the 50E -> 50G filter conversion thread and mentioning Carson's rule (honestly, I didn't really understand some of his numbers) makes me think that the receiver is really more optimized towards a higher deviation to help with Uniden's P25 Phase 2 decoding. I don't think we'll really know for sure unless Uniden cares to tell us.
The other quibble might be the dependence on the audio path in 12dB SINAD measurements. Given the well known audio problems the 536 had, maybe the 436 would look a lot better if the audio was pulled directly off the circuit board. Not to apologize for Uniden, but it's kind of hard to believe they would design a receiver that compares so poorly to earlier ones. Perhaps this is more of a packaging and layout issue than a receiver design problem.
In my days of crystal controlled scanners, the FM capture effect was more effective with wide band FM. You didn't need lots sensitivity to pull in a weak signal. But, that was a long time ago.
After pondering about it a little more, I think it really does. 12db SINAD is pretty much the gold standard for measuring analog receiver sensitivity. You may not enjoy casual listening at this level, but you can immediately compare it to say an APX 7000 (.216 uV or -122.5 dBm on VHF, .234 uV or -119.5 dBM on UHF) and know a lot about what to expect from the receiver.
Maybe it depends on the area where you live, but weak signal behavior is still important in my area which utilizes analog mutual aid and TACs on VHF, UHF and 800MHz. It's not exactly DX, but pulling out handhelds and mobiles working searches, fires and rescues still requires a good analog receiver in my area of monitoring.
If I had quibbles with the analysis, one might be using a 1.5KHz deviation. That's the right number for narrow band FM of course. But, given the post UPMan made in the 50E -> 50G filter conversion thread and mentioning Carson's rule (honestly, I didn't really understand some of his numbers) makes me think that the receiver is really more optimized towards a higher deviation to help with Uniden's P25 Phase 2 decoding. I don't think we'll really know for sure unless Uniden cares to tell us.
The other quibble might be the dependence on the audio path in 12dB SINAD measurements. Given the well known audio problems the 536 had, maybe the 436 would look a lot better if the audio was pulled directly off the circuit board. Not to apologize for Uniden, but it's kind of hard to believe they would design a receiver that compares so poorly to earlier ones. Perhaps this is more of a packaging and layout issue than a receiver design problem.
In my days of crystal controlled scanners, the FM capture effect was more effective with wide band FM. You didn't need lots sensitivity to pull in a weak signal. But, that was a long time ago.
Boatanchor
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Please do.
I along with others would be interested in your results.
And I agree that while the sensitivity difference may not affect most moderate to strong signals, handheld scanners using attached stubby antennas are often expected to receive much weaker signals than those connected up to base/mobile antennas.
The difference between 0.28uV and 0.5uV sensitivity makes a huge difference to weak signal digital decoding and trunk tracking ability.
B
I agree that digital and trunking change receiver design. Sensitivity becomes an all or nothing thing which it was not in the analog world. Thankfully, I live in an area where next to nothing is digital and there is only one relatively uninteresting trunked system.
And therein lies why we need different types of radios and big issues for some are not big issues for others.
I on the other hand, thankfully live in an area where there are digital and trunking systems up the wazoo. That's what makes scanning interesting to me. Don't ask me why, but digital and trunking turn me on "radio wise."
People may read my posts complaining about the sensitivity of the 436HP, but it (and the 536HP) are really what I need for most of my scanning needs in the center of the LA Basin. I have an ICOM R20 that is much more sensitive in terms of VHF and most UHF. The trouble is that you can drive an 18-wheeler through that radio selectivity wise. The 436HP and 536HP have little problem when it comes to selectivity.
Maybe it all comes down to the right radio "tool" for the right job and area. Santa Ynez is a beautiful area (my wife and I got married in Santa Barbara 38 years ago). If and when I head back up there, I will probably take at least one other scanner along with the 436HP.
But come to Los Angeles, and the issue at hand, namely sensitivity (which I admit bugs me about the 436HP) is really kind of an academic issue. But I realize that in many parts of the country where analog VHF and UHF are predominant, the sensitivity is a bit thing.
Now: Why can't someone get the whole thing right, sensitivity and selectivity (and good audio quality like the GRE/RS/Whistlers). Maybe I am asking too much. My FunCube Dongle Plus actually beats out most of my scanners just purely on a sensitivity issue.
Steve AA6IO
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.
That is interesting.
Without the equipment to test my own 436, all I can say is that my radio performs like Boatanchor's, not at all like yours--wanna trade?
Something's wrong somewhere here. My 436 can't hear at all or can barely hear many of the weak-signal analog transmissions my 396 receives clearly, even when I've got them both stopped (not scanning) on the same channel and using identical antennas (Comet HT-55's).
Production variations? Bad day at the factory? Quality-control issues?
Without the equipment to test my own 436, all I can say is that my radio performs like Boatanchor's, not at all like yours--wanna trade?
Something's wrong somewhere here. My 436 can't hear at all or can barely hear many of the weak-signal analog transmissions my 396 receives clearly, even when I've got them both stopped (not scanning) on the same channel and using identical antennas (Comet HT-55's).
Production variations? Bad day at the factory? Quality-control issues?
Exactly, which is why I was always puzzled by the reports of bad reception...and negative on the trade.
I notice you are using antennas attached directly to the unit and that may very well be the root cause, assuming the internal noise issue is true.
Hi, Kevin.
The internal noise issue was going to be my next guess as to what's going on here. I've never hooked up my 436 to an external antenna, but I will soon, so as to test that theory.
However, none of this explains Boatanchor's numbers, assuming he was using test equipment comparable to yours.
Thanks.
-Johnnie
The internal noise issue was going to be my next guess as to what's going on here. I've never hooked up my 436 to an external antenna, but I will soon, so as to test that theory.
However, none of this explains Boatanchor's numbers, assuming he was using test equipment comparable to yours.
Thanks.
-Johnnie
joeuser
The Wretched
I have limited experience with my BCD436HP on the VHF band. Most of the time it is in my office sitting quietly & picking up the KSICS TRS. Its hooked up to an external 800 MHz antenna. Therefore I don't try anything below 800 because its just horrible.
I have taken it out twice on trips. Both times I used the RS telescoping with center load whip. One trip was up to Nebraska. I was picking up VHF traffic three counties away, maybe 65 miles. This is inside our van. However, I don't know where the repeaters & stuff are but I think it did OK regardless. The other time was at a picnic & all I heard on the VHF was FRS/GMRS around the campground & some marine band chatter (used out here like CB radio).
Not scientific but I'm now interested in how the BCD436HP does vs. the BCD396XT, I'd rather carry around the 396 for the size esp. if it performs better.
I have taken it out twice on trips. Both times I used the RS telescoping with center load whip. One trip was up to Nebraska. I was picking up VHF traffic three counties away, maybe 65 miles. This is inside our van. However, I don't know where the repeaters & stuff are but I think it did OK regardless. The other time was at a picnic & all I heard on the VHF was FRS/GMRS around the campground & some marine band chatter (used out here like CB radio).
Not scientific but I'm now interested in how the BCD436HP does vs. the BCD396XT, I'd rather carry around the 396 for the size esp. if it performs better.
Boatanchor
Member
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- Jul 17, 2011
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- 991
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.
Wow, those figures look a hell of a lot better than mine!
It really does look like I have a lemon, or a Friday afternoon build
My radio was only purchased in the last few weeks too, so you would think that any production errors would have been fixed.
KevinC, when was your radio purchased?
Are you running the latest firmware?
I'm considering rolling back my firmware to an earlier version and retesting, although I would be surprised if there is any mechanism in the hard/software to manipulate the front end.
B
Wow, those figures look a hell of a lot better than mine!
It really does look like I have a lemon, or a Friday afternoon build
My radio was only purchased in the last few weeks too, so you would think that any production errors would have been fixed.
KevinC, when was your radio purchased?
Are you running the latest firmware?
I'm considering rolling back my firmware to an earlier version and retesting, although I would be surprised if there is any mechanism in the hard/software to manipulate the front end.
B
Mine was purchased the first week they came out and I'm on whatever FW is current.
I have someone local to me that reports his 536 is bad on VHF (very recently purchased) while mine (one of the first ones) appears to be excellent....So IDK...
Keeping in line with the VHF sensitivity here I have to chime in and say that scanners today are not built at all like the scanners from, let's say, 20yrs ago. And I am sure there is a good reason for that. Here is my opinion.
About 20yrs ago (or so) I owned a handheld Regency 1000 (or 1200) It received Vhf Lo, VHF high and UHF. (note the small amount of RF's to receive) With an outside antenna (basic Radio Shack model about $19.00) and some cheap RG59 or RG6 cable I could regularly pick up VHF high stations at night that were 70, 80, and up to 150miles away. I live in St Louis and nearly every night I could pick up sheriffs departments from Indiana, middle Illinois, rural MO and Paducah KY. I also had a couple Bearcat base scanners (table top) that could do almost as good. But they did not receive 700/800/900 and up frequencies. And this was not skip. (but I could talk for days about listening to LAFD every day during the summer on 33.70 and 33.82 for six hours a day. But I won't)
Scanners now days have to be able to tune/receive sooooo much more but as I found out, (right or wrong) on a Yahoo antenna group, the receivers/scanners have a "sweet spot" (sort of) to have good or great reception. One type of cable and one type of antenna can not "equally" receive a 33.06MHz signal and a 868.9375MHz signal the same. There is no way. You need an antenna and cable specific to a frequency group to optimize reception. Even the new NFM standard has greatly reduced reception. Not only on scanners but with professional radios too. I have always thought that scanner manufacturer's should come out with either a three scanner group specific to each major frequency group (Lo, High & 800) or one scanner that could have three tuners for each frequency group. I know, stupid right? Oh well.
My point is, I think that because most new systems in most cities, and states are 700/800 MHz trunked systems Uniden (and other companies) have probably fine tuned and focused their products for those bands. Meaning the VHF hi and low bands will suffer in sensitivity greatly.
Scanning is not the same as it was. I am old school. I do not use computers to do anything with my scanners. I program by hand (tiresome I know) but I have complete control over what goes in a system and group. And I learn how the scanner really works. Do I miss hearing those 150 mile away fire departments? You're darn right I do! Do I miss the joy of picking up another county in another state late at night? Absolutely! But that is not how things are now. It has gotten so bad in the St Louis area that every bordering county to St Louis (at least six (6)) have gone to or are in the process of going to 700/800 MHz trunked systems. I will be losing almost all reception of those counties because of the "way" the new systems work. Of the three counties in Illinois I can only pick up one. When the new systems in MO go online (up to three (3)) I will be losing at least 1 maybe 2 of them. It sucks folks. I hate it. All we can do is to do our best and make the most of technology. And I hope it works.
I am sorry to have taken up valuable time for most of you. Have a great weekend.
About 20yrs ago (or so) I owned a handheld Regency 1000 (or 1200) It received Vhf Lo, VHF high and UHF. (note the small amount of RF's to receive) With an outside antenna (basic Radio Shack model about $19.00) and some cheap RG59 or RG6 cable I could regularly pick up VHF high stations at night that were 70, 80, and up to 150miles away. I live in St Louis and nearly every night I could pick up sheriffs departments from Indiana, middle Illinois, rural MO and Paducah KY. I also had a couple Bearcat base scanners (table top) that could do almost as good. But they did not receive 700/800/900 and up frequencies. And this was not skip. (but I could talk for days about listening to LAFD every day during the summer on 33.70 and 33.82 for six hours a day. But I won't)
Scanners now days have to be able to tune/receive sooooo much more but as I found out, (right or wrong) on a Yahoo antenna group, the receivers/scanners have a "sweet spot" (sort of) to have good or great reception. One type of cable and one type of antenna can not "equally" receive a 33.06MHz signal and a 868.9375MHz signal the same. There is no way. You need an antenna and cable specific to a frequency group to optimize reception. Even the new NFM standard has greatly reduced reception. Not only on scanners but with professional radios too. I have always thought that scanner manufacturer's should come out with either a three scanner group specific to each major frequency group (Lo, High & 800) or one scanner that could have three tuners for each frequency group. I know, stupid right? Oh well.
My point is, I think that because most new systems in most cities, and states are 700/800 MHz trunked systems Uniden (and other companies) have probably fine tuned and focused their products for those bands. Meaning the VHF hi and low bands will suffer in sensitivity greatly.
Scanning is not the same as it was. I am old school. I do not use computers to do anything with my scanners. I program by hand (tiresome I know) but I have complete control over what goes in a system and group. And I learn how the scanner really works. Do I miss hearing those 150 mile away fire departments? You're darn right I do! Do I miss the joy of picking up another county in another state late at night? Absolutely! But that is not how things are now. It has gotten so bad in the St Louis area that every bordering county to St Louis (at least six (6)) have gone to or are in the process of going to 700/800 MHz trunked systems. I will be losing almost all reception of those counties because of the "way" the new systems work. Of the three counties in Illinois I can only pick up one. When the new systems in MO go online (up to three (3)) I will be losing at least 1 maybe 2 of them. It sucks folks. I hate it. All we can do is to do our best and make the most of technology. And I hope it works.
I am sorry to have taken up valuable time for most of you. Have a great weekend.
You're forgetting that TX power isn't what it used to be because the bandwidth is a lot more crowded than it was 20 years ago. And trunked systems don't have one mongo tranxmitter to cover an area, they have several smaller transmitters.
You're right about antennas being band-specific, but radios in general have gotten a lot better over the years.
You're right about antennas being band-specific, but radios in general have gotten a lot better over the years.
You have to realize that the old Regency HX-1000/1200/1500 radios were absolute killers on VHF high, like the truly awful AOR 900 was on 800MHZ. I kept my 1000 for years after it should have been retired, all duct taped together for years just because the VHF was so good. It was pretty decent on 400 megs too, but VHF was probably better than anything else I've ever had, with my Icom 24AT a pretty close second with much worse audio. A friend's HX-1500 is still working fine, and he uses it just for Railband at this point, as it's better than all his other stuff.
My PSR-500 and Pro-106 and 197's pick up pretty much anything I want to hear, well enough that I can stand to listen to it and not lock them out because the squelch popping or too much hiss. The X36 radios I've tried here have all failed miserably on anything VHF, regardless of the firmware versions. Toss in the SD card issues a couple of them have had, and I'll pass on these, let someone else have the headaches. I'll be more than happy to "take a look" at their new scanners, even though some of them don't work very well. If anyone asks me about the X36 scanners, I ask them, "Do you listen to VHF high?". If they say yes, I tell them to get an older model Uniden, or go to an RS/Whistler radio instead. You would think anything should pick up VHF high decently at this point, but not so..
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