Total noob to sdr - help please!

Status
Not open for further replies.

LIScanner101

Completely Banned for the Greater Good
Premium Subscriber
Joined
Feb 12, 2013
Messages
1,427
Location
Hicksville, Long Island, NY
Hello all,

Sorry for my VERY obvious ignorance on this subject. I asked something like this before, but I don’t think I ever got a clear answer – well, clear to ME at least LOL! I’ll try again and I’ll try to be as brief as possible:

I travel to CA a lot for business, and I always lug my BCT15X with me. I also carry a laptop for business calls. When I’m in the hotel room at night, I listen to my scanner while I work on my laptop.

Suppose that I still want to scan the airwaves, but leave the scanner at home? Now for my main questions:


1. Would it be less work to set up an SDR-based scanner in a hotel as opposed to just setting up a conventional scanner, or is it more complicated?


2. I mentioned not having to take my scanner with me anymore if I went the SDR route. Would I really be saving much real estate in my suitcase since I would still need to carry a receiver, or are these things small?


3. Can I monitor conventional, EDACS, MOT II, P25 and assign alpha tags to everything?
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
22,072
Location
Bowie, Md.
There are a great many online feeds, including the HF based ones. Why not take advantage of these, and not have to lug around a bunch of electronics that might be attractive to the wrong folks?

Mike
 

LIScanner101

Completely Banned for the Greater Good
Premium Subscriber
Joined
Feb 12, 2013
Messages
1,427
Location
Hicksville, Long Island, NY
There are a great many online feeds, including the HF based ones. Why not take advantage of these, and not have to lug around a bunch of electronics that might be attractive to the wrong folks?

Mike
Nah, nowhere near what I want. I like listening to exactly what I want to listen to. You get what you get with online feeds.
 

br0adband

Member
Joined
Apr 8, 2005
Messages
1,569
Location
Springfield MO
1) There are two possibles:

- for SDR you: unpack everything, find space to set everything up, plug in the laptop to the AC adapter (I'm guessing since you're mobile that's what you'd be using), plug in the USB RTL stick, plug in the antenna to the USB stick, boot the laptop, run the SDR software, run additional software as required, etc

or

- unpack the conventional scanner, plug in the AC adapter, attach the antenna, turn it on and you're good to go

Personally while I find SDR pretty compelling at this point, if I owned a BCT-15X I'd either: a) take it with me wherever I went as you have done in the past, or b) by a newer handheld that does everything I require, but that's just me.

... is it more complicated?
Hell yes it is, in most every respect. Is it worth the hassle? Well, you can do more with SDR and RTL sticks these days like decoding digital formats that no modern scanner - even the newest stuff just released by Uniden - cannot and most likely will never handle like DMR/MOTOTRBO, NXDN, and others.

2) Laptop, AC adapter, mouse (I can't stand touchpads and trackpoints, I always use a mouse, I have a Bluetooth one that's done well for me for years now), RTL stick, pigtail (assuming you want to attach a real useful antenna, that is), antenna cable, antenna (or antennas as the case may be). I have a Dell Latitude E6400 14.1" laptop and I can put all the necessary stuff in my laptop bag: the RTL stick, pigtail, a 6 foot BNC to BNC cable, and the two antennas I use for "mobile ops" are my Radio Shack 800 MHz and my Diamond RH77CA and that's about it. Those cover everything with more than acceptable performance for "mobile ops" and all that fits inside the outer pocket of my laptop bag without issues.

Of course getting all that stuff out of the bag and then set up someplace is more complicated but, if you simply cannot stand dragging that BCT-15X around any longer and you can't/don't/won't get a handheld to do the job, then sure, RTL sticks on the go are entirely possible.

3) Technically yes, you should be able to monitor most anything using an SDR application of some kind, Unitrunker to decode the trunking system control channels for EDACS, LTR, Motorola Type II, and so on. P25 is a digital communications protocol (more or less) and while Unitrunker can decode the control channel as required (and even tune an RTL stick for you given you have more than one - I think it's possible to monitor a digital system with just one RTL stick but it will have some lag as it switches back and forth from control channel to voice and so on), you will still have to use DSD or DSD+ in addition to everything else to be able to decode the actual P25 voice channels into audible speech.

So the basic answer to #3 is yes it's possible, but not anywhere near as simple as just carrying that BCT-15X with you, and I'm being completely serious. To do what you want to do requires (typically) at least 2 RTL sticks working at the same time and several applications all working at the same time doing a lot of background processing and decoding so you can monitor most anything at all. The BCT-15X can do most all of that save for digital comms like P25 and so on.

And yes, Unitrunker allows for alpha tagging the systems/talkgroups/radio IDs and can pull info from the RRDB if you have a subscription as well.

I'd still say it's easier to lug the BCT-15X around, and you can tap that if needed and still use RTL sticks if you wanted, adding in digital decoding capabilities with DSD/DSD+ as needed (not that you need the RTL sticks to do that; you'd just need a proper discriminator tap from the scanner).
 

shortwaver

Member
Premium Subscriber
Joined
Jan 20, 2012
Messages
202
Location
Lil Rhody
I'm not sure SDR is ready for prime time regarding scanner use.

It is possible, and fun to tinker with, but you still need a laptop (might already have one on your trips) and a decent antenna. I don't know if the 15x has a zip code input option, like the HP-1 or bcd436-536, but that's probably what I would want on the road- only because I want results quickly.
 

KC1UA

Scan New England Guru
Database Admin
Joined
Oct 27, 2002
Messages
1,586
Location
Cape Cod, Massachusetts
Why not do both? If you're taking the laptop with you anyway, the size of a few RTL dongles and the hardware required to connect to an antenna is minimal. For the short $$ they cost there's really no reason NOT to take them when you're on the road. They perform surprisingly well and once you learn how to use them with UniTrunker, SDR#, SDR-Radio, etc. they can make for a great addition to what you're monitoring via the 15X. Hear something that you want to specifically listen to? Use the dongles to tune it and keep on scanning normally with the 15X. Win Win in my book.

Have fun!
 

LIScanner101

Completely Banned for the Greater Good
Premium Subscriber
Joined
Feb 12, 2013
Messages
1,427
Location
Hicksville, Long Island, NY
1) There are two possibles:

- for SDR you: unpack everything, find space to set everything up, plug in the laptop to the AC adapter (I'm guessing since you're mobile that's what you'd be using), plug in the USB RTL stick, plug in the antenna to the USB stick, boot the laptop, run the SDR software, run additional software as required, etc

or

- unpack the conventional scanner, plug in the AC adapter, attach the antenna, turn it on and you're good to go

Personally while I find SDR pretty compelling at this point, if I owned a BCT-15X I'd either: a) take it with me wherever I went as you have done in the past, or b) by a newer handheld that does everything I require, but that's just me.



Hell yes it is, in most every respect. Is it worth the hassle? Well, you can do more with SDR and RTL sticks these days like decoding digital formats that no modern scanner - even the newest stuff just released by Uniden - cannot and most likely will never handle like DMR/MOTOTRBO, NXDN, and others.

2) Laptop, AC adapter, mouse (I can't stand touchpads and trackpoints, I always use a mouse, I have a Bluetooth one that's done well for me for years now), RTL stick, pigtail (assuming you want to attach a real useful antenna, that is), antenna cable, antenna (or antennas as the case may be). I have a Dell Latitude E6400 14.1" laptop and I can put all the necessary stuff in my laptop bag: the RTL stick, pigtail, a 6 foot BNC to BNC cable, and the two antennas I use for "mobile ops" are my Radio Shack 800 MHz and my Diamond RH77CA and that's about it. Those cover everything with more than acceptable performance for "mobile ops" and all that fits inside the outer pocket of my laptop bag without issues.

Of course getting all that stuff out of the bag and then set up someplace is more complicated but, if you simply cannot stand dragging that BCT-15X around any longer and you can't/don't/won't get a handheld to do the job, then sure, RTL sticks on the go are entirely possible.

3) Technically yes, you should be able to monitor most anything using an SDR application of some kind, Unitrunker to decode the trunking system control channels for EDACS, LTR, Motorola Type II, and so on. P25 is a digital communications protocol (more or less) and while Unitrunker can decode the control channel as required (and even tune an RTL stick for you given you have more than one - I think it's possible to monitor a digital system with just one RTL stick but it will have some lag as it switches back and forth from control channel to voice and so on), you will still have to use DSD or DSD+ in addition to everything else to be able to decode the actual P25 voice channels into audible speech.

So the basic answer to #3 is yes it's possible, but not anywhere near as simple as just carrying that BCT-15X with you, and I'm being completely serious. To do what you want to do requires (typically) at least 2 RTL sticks working at the same time and several applications all working at the same time doing a lot of background processing and decoding so you can monitor most anything at all. The BCT-15X can do most all of that save for digital comms like P25 and so on.

And yes, Unitrunker allows for alpha tagging the systems/talkgroups/radio IDs and can pull info from the RRDB if you have a subscription as well.

I'd still say it's easier to lug the BCT-15X around, and you can tap that if needed and still use RTL sticks if you wanted, adding in digital decoding capabilities with DSD/DSD+ as needed (not that you need the RTL sticks to do that; you'd just need a proper discriminator tap from the scanner).
Wow! I couldn't ask for a more thorough and well-thought-out response. THANK YOU!

It seems like my main motivating factors with going SDR instead of "hardware" - ease of packability, ease of setup and ease of use - won't be readily satisfied with SDR. I'm going to continue to go with hardware scanners for now.

Thanks again!
 

LIScanner101

Completely Banned for the Greater Good
Premium Subscriber
Joined
Feb 12, 2013
Messages
1,427
Location
Hicksville, Long Island, NY
I'm not sure SDR is ready for prime time regarding scanner use.

It is possible, and fun to tinker with, but you still need a laptop (might already have one on your trips) and a decent antenna. I don't know if the 15x has a zip code input option, like the HP-1 or bcd436-536, but that's probably what I would want on the road- only because I want results quickly.
I always travel with good antennas. I WAS using a "packable" vintage Antenna Specialists MON-52 but recently tried a wire OCFD taped to my hotel window and it worked fine, and it doesn't look like a giant spear to the TSA when my bags are going through the x-ray machines LOL :lol: !

As far as content goes, I just program in a "Bay Area" FreeSCAN file the night before I fly out so all I have to do is hook everything up and scan away. I WAS driving with my scanner on the passenger's seat a few times but it's a PITA to set up the trunk-lip antenna NMO mount on rentals so now I just scan in the hotel room.
 

LIScanner101

Completely Banned for the Greater Good
Premium Subscriber
Joined
Feb 12, 2013
Messages
1,427
Location
Hicksville, Long Island, NY
Why not do both? If you're taking the laptop with you anyway, the size of a few RTL dongles and the hardware required to connect to an antenna is minimal. For the short $$ they cost there's really no reason NOT to take them when you're on the road. They perform surprisingly well and once you learn how to use them with UniTrunker, SDR#, SDR-Radio, etc. they can make for a great addition to what you're monitoring via the 15X. Hear something that you want to specifically listen to? Use the dongles to tune it and keep on scanning normally with the 15X. Win Win in my book.

Have fun!
I thought about that too but don’t I still need some kind of “receiver” IN ADDITION TO the dongles? Or does a dongle have a tiny “receiver” inside of it too? As you can see I’m pretty darned ignorant on the subject :lol:
 

KC1UA

Scan New England Guru
Database Admin
Joined
Oct 27, 2002
Messages
1,586
Location
Cape Cod, Massachusetts
I thought about that too but don’t I still need some kind of “receiver” IN ADDITION TO the dongles? Or does a dongle have a tiny “receiver” inside of it too? As you can see I’m pretty darned ignorant on the subject :lol:
The dongle IS the radio, and it's controlled exclusively by the software (SDR#, SDR-Radio). Thus the term "Software Defined Radio". You'll be able to see 2 MHz of spectrum at a time, click on an observed signal, and tune immediately to it. Or, you can manually tune via software to the frequency of your choice. You will hear the audio of signals through your PC's speaker. It works astoundingly well for such an inexpensive piece of equipment.
 

LIScanner101

Completely Banned for the Greater Good
Premium Subscriber
Joined
Feb 12, 2013
Messages
1,427
Location
Hicksville, Long Island, NY
The dongle IS the radio, and it's controlled exclusively by the software (SDR#, SDR-Radio). Thus the term "Software Defined Radio". You'll be able to see 2 MHz of spectrum at a time, click on an observed signal, and tune immediately to it. Or, you can manually tune via software to the frequency of your choice. You will hear the audio of signals through your PC's speaker. It works astoundingly well for such an inexpensive piece of equipment.
Hmmmmm, maybe I need to take a step back here. What you are describing doesn’t sound anything like what a hardware scanner does. A scanner, well, “scans” (duh) a selection of pre-selected frequencies which could be anywhere from 30MHz to 1000MHz. What you have described looks like a manual radio (I guess that’s why it’s called “Software Defined Radio” and not “Software Defined Scanner” LOL!). Am I missing something, or is SDR not capable of emulating the functionality of a hardware scanner?
 

br0adband

Member
Joined
Apr 8, 2005
Messages
1,569
Location
Springfield MO
Mega-post ahead, be warned... ;)

A modern scanner from Uniden or GRE/Whistler is a combination of two primary things: a tuner to receive content being broadcast on frequencies, and firmware aka software to control the tuner/decode the audio (in analog or digital format) and provide it to the audio circuit so you can hear it.

An RTL stick is basically a scanner missing the software - it's a tuner that offers pretty much exactly the same basic functionality as far as receive content being broadcast on frequencies. The software component is provided by applications, programs, and software running on a computer that can allow for more functionality and true "hands on" control of most every single aspect involved, far more control than you'd get with any modern scanner. The software used can turn an RTL stick - depending on the complexity and feature-set of the software itself - into a communications receiver and not just a "scanner" but you still have that option as well (input a set of frequencies and then monitor just those frequencies in sequence, like a scanner does).

With RTL sticks - and by that I mean the most common models that use the RTL2832U chipset from Realtek coupled with the R820T tuner from Rafael - there is also the Elonics E4000 tuner but it's much rarer and more expensive nowadays because of the rarity as Elonics is no longer in business and they only offer a wider frequency range for reception - it is exactly what it purports to be: a "cheap USB TV tuner" that was designed to work with the European DVB-T digital TV format which will soon be replaced by something else (from reports). Someone discovered that you can use these sticks as radio tuners forgoing the actual TV/video aspect if you use the right drivers and the right software to make use of them in this respect.

Now, while they ARE very capable receivers, they obviously require that software to make use of them, hence the still somewhat recent "explosion of interest" towards SDR in general. The interest isn't because of Software Defined Radio which has been possible for many years now, the interest is solely because these "cheap USB TV tuners" give you the ability to do SDR type monitoring with extremely low cost - that's the primary draw. Sure, we'd all love to have a nice wide bandwidth USRP device from Ettus sitting on our desktops tuning in everything we can but very few of us are capable (or willing) to toss out several hundred bucks for such a device, or even a few grand for the highest end models.

To put it bluntly: no, you won't get the same exact experience with SDR and RTL sticks as you do with the BCT-15X or any modern base/mobile/handheld scanner. It takes a bit more effort to get the same or similar functionality in the long run, and obviously more hardware and software as well: a computer of some kind, the RTL stick(s), the drivers to make them recognizable to the software which is used to make them functional, and of course the potential additional need for more software to do trunking capabilities as well as yet another piece of software to decode the digital communications protocols now gaining traction in the radio communications world of today.

With SDR# (and potentially other SDR programs as well) it is possible to create a database of frequencies, even groups designated for particular purposes, and then "scan" the frequencies assigned to said group just as a modern base/mobile/handheld scanner would do, sure. There's a plugin for SDR# called Frequency Manager + Scanner plugin which does precisely that and I use it myself and have no issues at all with it. I can assign delay times to stay on a given frequency (to follow the comms), I can assign specific signal strengths to stop on (this is different from squelch, for the most part), and other aspects per group as required.

So yes, again, it's possible to use RTL sticks as "scanners," most definitely - it just takes more work to make it possible. And again, today's modern scanners, even the most current ones from Uniden can only decode P25 in terms of digital protocols, both Phase I, X2-TDMA, and the newest variant which is Phase II. Any other digital protocols like DMR/MOTOTRBO (gaining a lot of popularity very very fast in the business radio communications areas) and NXDN (also gaining popularity, especially with railroad operations) and now even D-Star (somewhat popular with Ham radio operators) cannot be monitored directly by any modern scanner but you can handle them using software like DSD or DSD+ (D-Star voice support was just recently added to DSD and it's still in progress too). Of course DSD and DSD+ can handle P25 Phase I and X2-TDMA - those decoders can't handle Phase II yet but there's always the hope that support will be added in the future.

The issue then becomes "Ok, I want to monitor <whatever protocol>, do I want to do it a) using my actual scanner and a discriminator tap fed into DSD or DSD+, or b) using RTL sticks doing the same thing with SDR software and DSD or DSD+?"

See the one thing there that remains the same between either a or b? You still have to have a computer involved at some point to decode those digital protocols... even with your BCT-15X.

So you have to decide something: do you want to (or need to) monitor strictly analog systems (which your BCT-15X is perfectly capable of doing without a single issue), or do you want to be able to monitor analog and digital systems like P25 (at the minimum Phase I and X2-TDMA if they exist in the areas you want to monitor), DMR/MOTOTRBO (in use most everywhere to some degree if you look for it), NXDN (not nearly as widespread but still in use in some areas), or even potentially D-Star (very limited use and it would require the dev build 1.7 of DSD to monitor at this time), and so on...

If everything you want to monitor is analog, stick with your BCT-15X since it's a known thing and you're familiar with it and traveling with it. If however you want to try some new things and learn something (keeping on top of current trends, etc) then adding an RTL stick or two is a great idea in the long run. As scancapecod said above, it's entirely possible to do both in the long run as an RTL stick or two along with the cables, antenna(s), etc are all very small and don't typically take up much space at all in a laptop bag.

And, another benefit: with an RTL stick added into the situation, you'd be able to monitor two systems at one time if you're really good at multitasking. ;)

Last last tip: forgot to mention this earlier but if you do have a laptop on the go (pretty sure you do) and you have intentions to get into RTL, I highly recommend getting an additional cable - a USB extension cable at least 3 feet long, maybe 6 would be better. The reason is to get the RTL stick out of the USB ports on the side(s) of your laptop which put them in a very fragile position should you drop it or potentially fall asleep with it and then roll over snapping off the USB stick at the point of connection. You'd be amazed at how many people get those 3G/4G wireless sticks from various cellular providers and they leave them plugged in all the time - at least till they drop the laptops or do just that, roll over on them when they fall asleep on a bed or couch and end up with a damaged stick and even worse a dead USB port on their laptops in the process.

Having the extension cable won't necessarily protect the USB port itself if such an event happens, but at least you save the stick from being destroyed in the process. Just a suggestion...
 
Last edited:

LIScanner101

Completely Banned for the Greater Good
Premium Subscriber
Joined
Feb 12, 2013
Messages
1,427
Location
Hicksville, Long Island, NY
br0adband,

Ok, now you've got me salivating like one of Pavlov's dogs LOL !

I was not aware that I could use my old fashioned (but VERY reliable) analog scanner along with SDR to decode a whole slew of really esoteric digital formats. This is a real eye-opener for me. It would conceivably save me the expense of plunking down anywhere between $350 to $600 on a new digital scanner, a device that can't even hold a candle to the formats an SDR dongle can handle. And that SDR "scanner" plugin you mentioned just made it even better!

Now I HAVE to try this!
 

br0adband

Member
Joined
Apr 8, 2005
Messages
1,569
Location
Springfield MO
Well, yeah, but realize you'll need to put a discriminator tap on that BCT-15X to make use of it for the digital decoding purposes which then requires a computer and DSD or DSD+ because you can't use the audio out from the headphone jack. You have to deal with baseband audio then you step into another issue which is getting a proper tap with a proper cable to provide the baseband audio to the computer, and then that's another issue because your laptop may not have a proper line-in but instead just a mic-in which then leads to potential issues of getting the audio levels correct for decoding, and then... and then... and then... (if you've seen "Dude, Where's My Car?" you should be on to the joke by now). :D

Anyway, yes you can use the BCT-15X if it's properly tapped, but in some respects using RTL sticks with SDR software and DSD or DSD+ is easier to utilize for digital decoding purposes.

The basic gist of all this hubbub is simple: RTL sticks are cheap, they work, and when coupled with SDR software for control purposes and DSD/DSD+ for digital mode decoding purposes they become a pretty powerful setup once you get the hang of it. It's easy to just spew out info since I'm pretty familiar with the setup now but at first it was somewhat frustrating (for the first hour or so) culling info from several different sources until I was finally getting actual audio from SDR# when tuned to a known frequency (NOAA weather is always there to use for that purpose, thankfully). Once I got that working the first time I did - as so many others - have the pretty common reaction of "I'll be damned, it works..." even when you know it'll work because so many others have made it happen for themselves.

But get one thing straight based on something you said:

I was not aware that I could use my old fashioned (but VERY reliable) analog scanner along with SDR to decode a whole slew of really esoteric digital formats.
SDR means Software Defined Radio by definition, so in truth if you're using the BCT-15X as your radio, it won't be using any SDR program to handle the digital decoding; it will be using a program designed to do one thing and one thing only: decode the digital protocols using DSD or DSD+ which are discrete - but not technically SDR - applications/programs. It's a fine distinction there that I felt was worth pointing out because so many people nowadays are just lumping the acronym/term "SDR" as anything related to using scanners of any kind along with a computer. If that were the actual technical requirement then I was "doing SDR" back in 2005 when I got my first BC-246T and Butel's ARC246 software... :p

Having said that there would be one situation where you'd be using the BCT-15X along with actual SDR software as well as Unitrunker to work together and that would be to monitor a P25 system properly: BCT-15X could supply the discriminator audio control channel feed to Unitrunker, which then decodes the control channel info and passes it to the SDR# trunking plugin (by way of a text file log with the necessary talkgroup/radio ID/voice channel frequency info) which causes SDR# to tune the RTL stick to the voice channels as they change and that audio is passed to DSD or DSD+ for the actual P25 data stream decoding and the final result is you get the audio aka digital speech from the speakers of the computer. Sounds complicated in text when describing it but it's basically one long signal path from beginning to end. You can even do that with 2 RTL sticks and Unitrunker + DSD/DSD+ nowadays, no SDR# required.

The reason I point out P25 is two-fold: first, it's well established having been in use for many years now and the protocol is published so that apps like Unitrunker can readily decode the control channels as required and then there's DSD and DSD+ which can then decode the actual voice content from the digital streams sent over the voice channels, that leads to the secondary reason which is that P25 trunked systems are easily monitored as well as conventional with such a setup. DMR/MOTOTRBO and NXDN are also available in either conventional or trunked systems but as of today there's nothing (at least that I'm aware of) that can properly monitor a trunked version of either protocol - you end up just being able to monitor them a channel at a time and following a conversation as it hops frequencies is no easier than monitoring something like an analog Motorola Type II system with a scanner that only does banks/channels, basically ain't happening to any useful degree. Sure you can tune the frequencies but you can't follow the conversations properly and you miss out on a great deal of traffic in the process.

While SDR along with DSD and DSD+ allow for you to monitor far more digital communications than any modern scanner, it's still a "hit or miss" proposition in terms of following the conversations on anything but a P25 based system (either conventional or trunked).

Anyway, it's some fun stuff for sure and it is so low in cost it sure can't hurt to give it a go. As for using SDR and RTL sticks to totally replace a $350-600 scanner, realize that most people aren't adding the cost of the computer they'll be using towards "doing SDR" duties - even if you paid for the computer many years ago, it should still be considered as part of the overall cost AND... that's a big and there... there's always the requirement for more hardware involved to "do SDR" reliably - it's more than just buying a $10-20 stick and that's that, obviously. There's time involved to learn things, gain experience, tweak this, tweak that, and so on.

Is SDR worth the time and effort and expense? Most assuredly.

Is SDR the same as just grabbing a handheld or mobile scanner and turning it on? Hardly.

Is SDR pretty capable overall of doing a lot of stuff that even the most sophisticated and advanced scanners on the market today - and the foreseeable future of 1-3 years - not capable of and potentially never capable of for a variety of reasons? Most definitely and that's part of the draw - aside from the low cost - of pursuing RTL sticks and SDR technology.

So get to it, and have fun, always... :)
 
Last edited:
Status
Not open for further replies.
Top