BCD536HP vs. SDR - Portland Police & Multnomah County

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johnsland8

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I use a mag mount antenna when I travel, and I set up a Fav List ahead of time so I’m only GPS scanning the things I want to scan
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Great tip. I'll have to try that.

and also so I can verify and or edit the location data that comes from the Radio Reference database as that data be quite inaccurate.
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I've found this to be true as well. I wasn't getting anything from some of the channels they listed so I used the waterfall in SDR Sharp to find the most activity. It seemed obvious which was the control channel and which were the voice channels. That's how I ended up with 853.7600. I think the actual channel is 853.7625? but I got the best reception at .7600... could be wrong about that? but it works either way.
 

sparklehorse

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Great tip. I'll have to try that.



I've found this to be true as well. I wasn't getting anything from some of the channels they listed so I used the waterfall in SDR Sharp to find the most activity. It seemed obvious which was the control channel and which were the voice channels. That's how I ended up with 853.7600. I think the actual channel is 853.7625? but I got the best reception at .7600... could be wrong about that? but it works either way.

Yes, I’m sure 853.7625 is accurate. I didn’t look at the DB carefully enough when we discussed that frequency yesterday. So disclaimer: I’m no expert with SDR dongles, but as I recall they tend to drift off frequency as they warm up. Perhaps you’re aware of this issue already, I don’t know. It‘s been a while since I’ve used one, but I think there is a way to calibrate it to the correct frequency after it‘s come up to temperature, which does take a while. Once you get the offset figured out you can usually leave it, but you’ll need to let it come up to temperature each time for it to be accurately on frequency. That’s my recollection anyway. I‘m sure someone will chime in if I‘m getting any of that wrong.
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sparklehorse

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And yes, the RR database, while generally pretty good with frequency and system information, can be quite bad as far as location data. All that data is submitted by users like you and I, none of it is official, and I don’t think it’s vetted carefully, or at all. It’s the Achilles Heal of GPS-based scanning, because that method relies on the inaccurate RR data. One thing that’s pretty common, is that for some counties the small towns have the same location data as the county they are in. Take Clatsop County for instance. The city of Astoria has the same location data as Clatsop County. As you’re driving north on Hwy 101 (and still in Tillamook County) your 536 will unlock the Astoria frequencies at the same point it unlocks the all county channels, LONG before you want Astoria scanned, long before you’re in radio range of Astoria. You don’t want those channels enabled until just before you enter their jurisdiction, at least I don’t. For a city that size a 5 mile radius, centered on the center of town, is usually about right. So that’s where making your own Fav List for travel allows you to edit that location data as you see fit.


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jonwienke

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I understand the SDS is better for simulcast because it's different technology so don't roast me too hard for my next comments but it's not like simulcast is new or uncommon. On the surface, it's kind of funny to say "you're $400 scanner isn't really good at large metro area scanning but it's pretty good at everything else you don't want to listen to. What you really need is a $700 scanner for that" OR I could just pay $20 for a dongle and use freeware to get pretty good results. I'm sure the SDS200 is better than a dongle for simulcast, but is it $20 vs $700 better? I'm sure that would be much more of a personal opinion than a literal one, but you get my point.

If you dig through the forum archives, you'll find that issues with and complaints about simulcast reception have been one of hottest topics here for several years. And that's why the introduction of the SDS models was such a big deal--for the first time, a scanner could monitor simulcast reliably without doing stupid antenna tricks that only worked for fixed locations and were useless for mobile scanning. If you had done so prior to purchasing the 536, perhaps you wouldn't have spent the money on the 536, and then been disappointed discovering it wasn't the right tool for the job.

The SDR software uses the same kind of I/Q sampling math that the SDS scanners and the commercial radios use to process and decode simulcast signals correctly. But the limitations of the SDR software lend it to only monitoring a single system at a time, and the $20 SDR dongles don't have as good of a front end or filtering to reject off-frequency interference. If the dongle + software combination works for you, there's nothing wrong with using it. The SDS scanners are far more useful for scannning multiple systems, and scanning while mobile (especially with GPS). You'll have to decide whether the cost is worth it to you.
 

johnsland8

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If you had done so prior to purchasing the 536, perhaps you wouldn't have spent the money on the 536, and then been disappointed discovering it wasn't the right tool for the job.

I actually did do a fair amount of research. I did know the general consensus was that it is not the best solution for simulcast but there were plenty of people who seemed to have decent success with it, depending on where they were. At least enough to be happy with it. I think I was just hoping to be one of the "lucky" ones. My comments here have been related to being unhappy with my local simulcast but that's not really the main reason I bought the 536. It was more for the GPS/WiFi/Mobile capabilities. I just haven't had a chance to utilize it for that yet. And like I said, I'm not trying to knock the scanner, it seems nice. I am just disappointed in this particular aspect. But, as you pointed out, it's not the right tool for that job so I guess that should be no surprise.

But the limitations of the SDR software lend it to only monitoring a single system at a time, and the $20 SDR dongles don't have as good of a front end or filtering to reject off-frequency interference.
This is a good point. It obviously does have some significant limitations compared to the vast capabilities of the SDS units. And I agree everyone has to determine what their cost per result threshold is.

Thank you for taking the time to reply and share your thoughts and input. I appreciate all the insight and information.
 

jonwienke

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"Depending on where they were" is the key takeaway. I've done a fair amount of mobile simulcast comparison testing between the 436 and the SDS100, with both connected to the same antenna in my truck, listening while running errands and such in a simulcast area. The SDS was pretty rock-solid, but the 436 varied between getting everything and nothing, sometimes going from one extreme to the other on opposite ends of a Walmart parking lot.

You may have some success at home using a directional antenna to focus your reception on one specific tower in the simulcast cell, but that won't work mobile.
 

sparklehorse

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I wouldn’t give up on the 536 for monitoring Portland just yet. There’s a good chance you can get it to work at least semi-decently. From your location I’d focus on trying to get a better signal from East Simulcast. Try the telescopic antenna that came with your radio. Collapsed all the way it might give better results than your discone. Using that back-of-set antenna, try putting the radio in a different room of your house. Sometimes even a move of a few inches can make a difference. Try the site settings I mentioned earlier. Try different site settings. Try West Simulcast if you just can’t get anywhere with East. If none of that helps, try this cheap cell phone yagi:


You‘ll need good coax and the proper coax adapters for that yagi to work, but these are small antennas and sometimes get the job done without mounting them outside.

Experiment, it’s part of the hobby!
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devicelab

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You might want to try a bandpass filter inline between your scanner and antenna. They're not super cheap but worth every penny if you're into the scanning hobby.

You can sometimes find good deals on E-Bay but Mini-Circuits sells a good one for a respectable price:



Also, I highly recommend a FM-TRAP filter in any scanner setup these days -- unless you're really out in the boonies. The RTL-SDR blog model I've tested is very good:


RTLSDR-FMTRAP.JPG
 

johnsland8

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Thank you for the suggestions. I might have to give them a try.

As suggested previously, I did test out the scanner replacing the discone antenna with the telescoping one that came with it and surprisingly(to me anyway) it picked up more activity. The reception on many of the calls was not any better but it did seem to pick up more.

How do you like your NanoVNA? I'm waiting for mine to be delivered any day now...
 

devicelab

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How do you like your NanoVNA? I'm waiting for mine to be delivered any day now...

I have the NanoVNA-F model which is WAY better. If you got the first gen then return it and get the newest generation. I love mine. It's the best thing since sliced bread!

 

kd7jfv

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And yes, the RR database, while generally pretty good with frequency and system information, can be quite bad as far as location data.


View attachment 78292

I thought I had gone through all categories and subcategories fixing location data, but it appears I did miss a few. If you find any others that don't have the appropriate location data please let me know of send in a submission.
 

philipwiller

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Hello My name is Phil I will be purchasing a digital scanner soon. What would you recommend for this? I am wanting to listen to all PPB and fire. I know they are all on digital now. I have programmed trunking scanners in the past. Never a digital one. I am looking for recommendations. What will be needed? Thank you in advance
 

Fielder3

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Hello My name is Phil I will be purchasing a digital scanner soon. What would you recommend for this? I am wanting to listen to all PPB and fire. I know they are all on digital now. I have programmed trunking scanners in the past. Never a digital one. I am looking for recommendations. What will be needed? Thank you in advance

I use a base/mobile Uniden BCD996 P2 for the Salem/Marion County area. Works good on Salem's New P25 system, and the State of Oregon 800 radio system. It's way less than a SDS. It's EASY to download radio data from Radio Reference directly to the radio itself. For a newbie, it's less complicated and easier to operate than the $700.00 SDS. My next radio will probably be a 800mhz/VHF Unication radio though :)
 
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