SDR Newbie Questions

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dwh367

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After 35 years I've pretty well scanned everything there is to scan so far. I'm looking for something new to play with both to keep myself interested in the hobby and to learn something new in the process. Before I jump in with both feet, I had a few basic questions that I was hoping someone would be able to answer.

1.) Does something like this look like it would be good for a beginner to start with? How to Make a $19 Police Radio Scanner

2.) I take it something like this doesn't really scan and a person would have to monitor one type of system at time? It wouldn't really be a problem. I'm just curious.

3.) I have a spare netbook that I could dedicate to SDR laying around (Windows XP, 512KB L2 Cache, 1.66MHz Atom Processor, 1GB DDR2 RAM). With this be enough to run an SDR?

Thanks!
 

br0adband

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1) Yep, as many folks have used that guide and similar ones of late (I found some info in that one as well as several others - there isn't just one single guide out there that really provides enough info itself so cull info from all sources to learn the most you can).

2) With SDR# and the Frequency Manager + Scanner plugin (note that this is a totally separate and more feature-laden plugin than the very simplistic one that comes included with SDR# itself) you can create scan groups (by name) and then assign specific frequencies to be included in that particular group after which you can "scan" the group which will make SDR# tune them jumping from frequency to frequency, with potential delays put in place, specific signal strength(s) to cause it to stop on a frequency, and other aspects.

3) There's no way to know till you give it a shot. There are reports from people that dedicate such hardware to the task of being SDR-specific machines and some have good luck, some don't, but as just stated, you'll just have to hook everything up and install or use whatever software is required (including the Zadig drivers for the RTL stick(s) installed properly) and then give it a run and see how it works out. Running SDR# (that's my app of choice, but don't limit yourself to just that one as there are several others: SDR-Radio (gotta love that redundant acronym), RTL-SDR, HDSDR, GNU Radio, and so on and yes some of those are Linux-based software.

Here's the biggest thing I can say overall: if you think you're gonna hook up a "cheap USB TV tuner" and do everything your handheld or mobile scanner does by design, well, you're going to be somewhat disappointed. You can do a lot with SDR at this time, but one could still consider the entire SDR concept as somewhat new and still limited by the lack of software to do most everything that modern scanners can do.

The other issue is that there's no one single app that can do everything - you typically are required to use several apps at the same time to get a task done. You can use Unitrunker nowadays (as of preview version 1.0.27.10) to control 2 RTL sticks (or some other hardware): one for the control channel and to be decoded which then passes the info to the second stick for tuning the voice channels. I personally did get that setup working but I had a lot of interference for some reason on the voice channels only when using Unitrunker as the controller for both RTL sticks. I've since moved to a setup where I tune the control channel with Unitrunker and then feed the voice channel info to SDR# by way of the trunking plugin and it works much better for me.

And that's just analog: if you want to listen in on digital comms like P25, DMR/MOTOTRBO, NXDN, or something else then you end up adding yet another program in the mix - either DSD (the original version) or the newest application known as DSD+ (while their names are similar, they are not the same programs, not by the same people either, so DSD+ isn't just a new improved DSD by the same person or persons). You add one of those apps into the audio signal path (baseband audio) and they will decode the digital data streams into audio aka the speech you're hoping to monitor. A lot of folks use one of the virtual audio cable drivers also that allows you to easily pass audio to the programs through the Windows mixer; I use one called VB-Audio Virtual Cable myself, donationware, and it works without issues and for me hasn't required any configuration at all - I installed it and voila, it just worked.

Last last tip: if you intend to do this, you're going to need a better antenna than the el cheapo practically useless one that comes with these RTL sticks, the tiny little 4-5" ones that are nothing to write home about. Get a pigtail with your RTL stick or order one from an eBay or Amazon reseller that allows you to hook up a proper antenna: for my 2 RTL sticks, I have 6" MCX (on the RTL stick side) to BNC female pigtails and haven't had any issues with them since I got them. A must-have thing if you wish to get into using RTL sticks, most definitely.
 

Your_account

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I have a spare netbook that I could dedicate to SDR laying around (Windows XP, 512KB L2 Cache, 1.66MHz Atom Processor, 1GB DDR2 RAM). With this be enough to run an SDR?
I have an Lenovo Ideapad white the same configuration and its to Slow for.
I can Run RTl1090 but nothing white an Waterfall or so.
You need an Laptop for when you want any good results for.
 

dwh367

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There's no way to know till you give it a shot.
Thanks for going into such detail in answering my question. I found it to contain some very useful information to help get me going. My plan is to start out simple as I know there will be a substantial learning curve involved. Then I can upgrade my hardware and software as I gain experience. This looks like it could turn out to be really interesting to play with.
 

KC1UA

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Thanks for going into such detail in answering my question. I found it to contain some very useful information to help get me going. My plan is to start out simple as I know there will be a substantial learning curve involved. Then I can upgrade my hardware and software as I gain experience. This looks like it could turn out to be really interesting to play with.
Once you use one of these nifty little devices and get used to being able to seeing radio signals as opposed to blindly tuning for them, you may never want to return to the "old" way of doing things.

I've said it many times, these dongles are game changers for anyone in the hobby, especially those that like to search for signals, and at the low cost there is really no excuse not to own at least one and learn how to do it. You can't go wrong for $20 or so. :D
 

Your_account

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I've said it many times, these dongles are game changers for anyone in the hobby, especially those that like to search for signals, and at the low cost there is really no excuse not to own at least one and learn how to do it. You can't go wrong for $20 or so.
I dont agree white that.
I use 10 Dongel for "realtime" Data Decoding. Its insate to buy 10 hight Quality Products when 10 low Price can the Same.
White some little and cheap way its possible to get an better Signal!
In my Case i use 2 Soup Can for Shielding.
 

dwh367

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I've said it many times, these dongles are game changers for anyone in the hobby, especially those that like to search for signals, and at the low cost there is really no excuse not to own at least one and learn how to do it. You can't go wrong for $20 or so. :D
That's exactly what I thought when I started researching it!
 

br0adband

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Also, while a lot of people do own Netbooks (Atom powered hardware, potentially something from AMD as well in their APU lines), those very low powered processors basically choke when trying to do a lot of stuff at the same time as SDR almost always requires - there's the SDR program itself (whichever one you choose, I use SDR# exclusively myself), then potentially adding Unitrunker at the same time (to decode trunking control channels), and then potentially adding DSD or DSD+ to decode the digital protocols into speech (rather CPU intensive in some respects; DSD+ uses less than DSD in my experience), and of course you could have 2 sticks which would mean potentially doubling up on everything since there's two of them.

My recommendation is if you don't have a machine capable of handling all that, and not many Netbooks can (if any, as I've never seen one that can do it, even running XP with 2GB+ of RAM), would be to look into getting an older laptop like a ThinkPad T60 or T61, an HP EliteBook or ProBook (older models), or a Dell Latitude E6400 (which is what I use) - those older Core 2 Duo powered machines have been flooding the used computer market for the past year or so because millions of 'em came off their long term leases in the business sector to be replaced by newer models and you can get them pretty cheap nowadays, like between $100-150 and they're still very powerful machines that can handle SDR duties easily.

There's always the market for used older desktop PCs as well, but I personally would say avoid anything with a Pentium 4 in it (or AMD single core) - dual core is the way to go on an older machine at least for SDR purposes, and at least 2GB of RAM if possible. I looked at craigslist in my area (Las Vegas) just now and it's loaded with Core 2 Duo powered desktops with 2-4GB of RAM - complete systems with LCD displays too - for $75 to $150 - and again it's because they came from businesses that completed their long term leasing and dump them on the used market resellers dirt cheap.

Just some things to consider if you're interested... Netbooks are nice for their intended purposes (basically doing one thing at a time like web browsing or email, maybe watching a video) but when you try to do multiple things at one time - as SDR monitoring pretty much requires - it's going to offer up seriously low performance by comparison.

Good luck...
 

Your_account

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I have an T61 and i can run only one SDR# Sessio at the time and when the CPU are 100% full.

And dwh367 please use the
Button its for free.
 

br0adband

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There are many ways to reduce the CPU usage with SDR#, the most common and easiest is to reduce the FFT waterfall resolution to 8192 or even 4096 for that matter. I've seen people using the higher settings of 16384+ and it just drains the CPU pretty severely and for no real significant reason. Also, change the range of the FFT so it only shows signals just above the noise floor of your given setup. My particular RTL sticks and how I've got them attached (using 12 foot USB extension cables with the shielding on the stick end removed to ensure adequate noise reduction) give me a noise floor around -65dB so I know that anything below those levels won't be of any use at all and if anything exists it'll be visible on the waterfall anyway.

Most people never alter the defaults of SDR# and never realize they're horribly inefficient in terms of actual visibly useful info... and with respect to the resolution of the FFT, a massive CPU hit for no good reason too. My Dell Latitude E6400 uses a Core 2 Duo P8700 processor running at 2.53 GHz; I know the T60 and T61 ThinkPads had Core Duos in some of the original models (and then Core 2 Duos in the later ones) which obviously isn't as powerful but you can still do some things to decrease the overall CPU usage with SDR#.

EDIT:

And of course, if you're using the computer for all sorts of other stuff at the same time as trying to use SDR# or whatever it's all going to add up. :p
 
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dwh367

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There are many ways to reduce the CPU usage with SDR#, the most common and easiest is to reduce the FFT waterfall resolution to 8192 or even 4096 for that matter. I've seen people using the higher settings of 16384+ and it just drains the CPU pretty severely and for no real significant reason. Also, change the range of the FFT so it only shows signals just above the noise floor of your given setup. My particular RTL sticks and how I've got them attached (using 12 foot USB extension cables with the shielding on the stick end removed to ensure adequate noise reduction) give me a noise floor around -65dB so I know that anything below those levels won't be of any use at all and if anything exists it'll be visible on the waterfall anyway.

Most people never alter the defaults of SDR# and never realize they're horribly inefficient in terms of actual visibly useful info... and with respect to the resolution of the FFT, a massive CPU hit for no good reason too. My Dell Latitude E6400 uses a Core 2 Duo P8700 processor running at 2.53 GHz; I know the T60 and T61 ThinkPads had Core Duos in some of the original models (and then Core 2 Duos in the later ones) which obviously isn't as powerful but you can still do some things to decrease the overall CPU usage with SDR#.
More good information to know. Thanks!
 

dwh367

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Also, while a lot of people do own Netbooks (Atom powered hardware, potentially something from AMD as well in their APU lines), those very low powered processors basically choke when trying to do a lot of stuff at the same time as SDR almost always requires - there's the SDR program itself (whichever one you choose, I use SDR# exclusively myself), then potentially adding Unitrunker at the same time (to decode trunking control channels), and then potentially adding DSD or DSD+ to decode the digital protocols into speech (rather CPU intensive in some respects; DSD+ uses less than DSD in my experience), and of course you could have 2 sticks which would mean potentially doubling up on everything since there's two of them.

My recommendation is if you don't have a machine capable of handling all that, and not many Netbooks can (if any, as I've never seen one that can do it, even running XP with 2GB+ of RAM), would be to look into getting an older laptop like a ThinkPad T60 or T61, an HP EliteBook or ProBook (older models), or a Dell Latitude E6400 (which is what I use) - those older Core 2 Duo powered machines have been flooding the used computer market for the past year or so because millions of 'em came off their long term leases in the business sector to be replaced by newer models and you can get them pretty cheap nowadays, like between $100-150 and they're still very powerful machines that can handle SDR duties easily.

There's always the market for used older desktop PCs as well, but I personally would say avoid anything with a Pentium 4 in it (or AMD single core) - dual core is the way to go on an older machine at least for SDR purposes, and at least 2GB of RAM if possible. I looked at craigslist in my area (Las Vegas) just now and it's loaded with Core 2 Duo powered desktops with 2-4GB of RAM - complete systems with LCD displays too - for $75 to $150 - and again it's because they came from businesses that completed their long term leasing and dump them on the used market resellers dirt cheap.

Just some things to consider if you're interested... Netbooks are nice for their intended purposes (basically doing one thing at a time like web browsing or email, maybe watching a video) but when you try to do multiple things at one time - as SDR monitoring pretty much requires - it's going to offer up seriously low performance by comparison.

Good luck...
I have a quad core desktop and my wife has a dual core desktop. Either of those could be used to get me started if need be. Looks like I'll have to invest in a better portable computer, somewhere down the line, to dedicate to SDR. Thanks!
 

Your_account

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dont post 2,3,.. or more time. Use the Edit Button when you want to add some additional information.
 

BM82557

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There are many ways to reduce the CPU usage with SDR#, the most common and easiest is to reduce the FFT waterfall resolution to 8192 or even 4096 for that matter. I've seen people using the higher settings of 16384+ and it just drains the CPU pretty severely and for no real significant reason.

Other points to remember about reducing SDR#'s cpu requirements are to use the SPEED slider cautiously (the faster the setting the more cpu cycles are used) and the old trick just to minimize SDR#'s window once you've made the settings needed for monitoring a system/freq. In my case SDR# un-minimized uses 35 - 40% cpu while minimized it uses 20 - 25%.
 

dwh367

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dont post 2,3,.. or more time. Use the Edit Button when you want to add some additional information.
I understand what you're saying now. However the edit button is only available for a couple of hours after the post. After that it disappears. It's also easier for others to follow a thread if the comments follow the posting rather than trying to reply to several posts all at the same time.
 

mikewazowski

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Your_account, please do not tell people how they should post.
As you've been told, the edit button is not available after a certain amount of time. As well, not everybody writes their post out before posting.
If you have a problem with how somebody posts, please use the Report Post icon to inform the moderators. Your posts have added nothing to the thread and are off topic.

Thanks.
 
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