Would like to decode NEXEDGE

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yeshuaisiam

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My local PD uses the NEXEDGE system.

This is basically going to be a 2 part question and I'll try to keep it in non-book length.

I have not used scanners recently, in fact its been 25 years. I want to get back into the hobby namely for my sons and I to have something to do together. I remember some of it, and was only somewhat a novice in it.

I have HEAVY LINUX experience. Already have the DSD software compiled and installed.

So basically for Christmas we are looking for a scanner. I understand that I may need to solder a discriminator into a scanner which is okay, but would rather not be involved in too much electronic surgery.

So at this point there are two questions that I have.

1) Is it possible for me to use a scanner and get NEXEDGE "clearly" while using he DSD program through my linux box?

IF SO -

2) What is the best scanner for the job? What would be the best for an easy discriminator if needed?

Also, we are planning on having an external antenna. Which is a good one for the day?

I've looked all around and a Uniden BCD99XT kind of stands out, but is expensive....

Basically I don't want to be "too" limited and want to upgrade scanners later. If I have to spend a buck now I'd rather do it at the beginning, HOWEVER if the BCD99XT would be overkill and I could do a lot of functions on a cheaper scanner I'm open to suggestions.

Sorry, I do know there are a ton of variables. Since I'd like to do this for Christmas for my sons (and NEXEDGE is possible to hear through the software - as I posted), I don't have a ton of time to sort out all the features and details. I'd just like somebody with far more experience in scanners to "hold my hand" on this one.

I'd honestly rather "grow into it" than to "grow out of it".

The look on my 10 year old son's face grinning ear to ear when I put a discriminator on our VERY cheap back of the closet bearcat scanner sold me that he likes this stuff. Heard a few things through the software - ;o) Chip off he old block. :eek:)

So anyway, is it possible to get the NEXEDGE and if so can somebody help me pick a great scanner for it?
 

ka3jjz

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Hi - since you didn't mention where you are, nor put this into your profile, it's nearly impossible to know which freq range your local police are using - and that makes a scanner recommendation equally difficult. I also suspect your 'BC99XT' is really a BCD996XT, and while it's certainly possible to put a discriminator tap (not a discriminator - all scanners already have one...) it's not necessary to break the bank for this. In fact, if you look at the DSD wiki article below, there's a section there with working setups. You will notice some folks using ham gear, and many using older scanners....

Digital Speech Decoder - the RR wiki

So in summary there's ample evidence to suggest using older scanners as a data source will work just fine. We even have an article or two linked in that same article above with instructions on how to make the tap, including the series of articles by the late Bill Cheek - widely regarded as the 'father' of this procedure. There are even 1 or 2 folks floating around the web that will do the tap for a fee. In point of fact, if you already have a scanner with a tap, it might be enough with which to get started (as you mentioned in the message)

However keep in mind that if you want to hear other things with the scanner besides NexEdge, and they use P25 digital modulation (the only kind that is decodeable right out of the box), then yes, a bit more expense is involved.

As for an antenna, once again it's very important to know where in the freq range we're talking here - but in general a good quality discone with the right coax will be a place to start. A ScanTenna ST2 or even the one sold by RS are also good choices (with the proviso that both antennas could suffer if the weather is severe - we have yet another article in our wiki that shows you how to reinforce the ST2). We have a specific forum devoted to scanner antennas, and I'd encourage you to check that out.

I would strongly encourage you to put something in your profile to indicate where you are (county/state will do), and also be sure to carry along somewhere the URL of the department you're trying to hear. You would also be wise to be more specific about your antenna needs; can you put something outside? If indoors, how much space do you have to work with? What are your frequency requirements (including hearing your local NexEdge system)?

The more background information you provide the better the answers will be.

best regards..Mike
 
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Gator596

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Yeshuisiam - Welcome to Radio reference! You are already talking teck WAY beyond my ability, but I will tell you that getting your son involved in scanning at ANY level is a good thing. Even just listening to stuff that comes through in the clear without encryption is educational and rewarding. My son first started listening only because I was listening (on a BCD996xt) and now he has an interest of his own. Scanning is a window to the people and organizations who "make the world go around" and I applaud you for being involved in such a worthwhile father and son project.
 

yeshuaisiam

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Dallas, TX
Hi - since you didn't mention where you are, nor put this into your profile, it's nearly impossible to know which freq range your local police are using - and that makes a scanner recommendation equally difficult. I also suspect your 'BC99XT' is really a BCD996XT, and while it's certainly possible to put a discriminator tap (not a discriminator - all scanners already have one...) it's not necessary to break the bank for this. In fact, if you look at the DSD wiki article below, there's a section there with working setups. You will notice some folks using ham gear, and many using older scanners....

Digital Speech Decoder - the RR wiki

So in summary there's ample evidence to suggest using older scanners as a data source will work just fine. We even have an article or two linked in that same article above with instructions on how to make the tap, including the series of articles by the late Bill Cheek - widely regarded as the 'father' of this procedure. There are even 1 or 2 folks floating around the web that will do the tap for a fee. In point of fact, if you already have a scanner with a tap, it might be enough with which to get started (as you mentioned in the message)

However keep in mind that if you want to hear other things with the scanner besides NexEdge, and they use P25 digital modulation (the only kind that is decodeable right out of the box), then yes, a bit more expense is involved.

As for an antenna, once again it's very important to know where in the freq range we're talking here - but in general a good quality discone with the right coax will be a place to start. A ScanTenna ST2 or even the one sold by RS are also good choices (with the proviso that both antennas could suffer if the weather is severe - we have yet another article in our wiki that shows you how to reinforce the ST2). We have a specific forum devoted to scanner antennas, and I'd encourage you to check that out.

I would strongly encourage you to put something in your profile to indicate where you are (county/state will do), and also be sure to carry along somewhere the URL of the department you're trying to hear. You would also be wise to be more specific about your antenna needs; can you put something outside? If indoors, how much space do you have to work with? What are your frequency requirements (including hearing your local NexEdge system)?

The more background information you provide the better the answers will be.

best regards..Mike
Thanks for the information Mike.

I would like to scan Cedar Hill, Lancaster, and Desoto TX Police, Fire, and dispatch. We would also like to hear aircraft, military, Ambulances, and my kids would laugh if we could hear drive thru window communication from local fast food. Those three cities above work out of one dispatch. I know that Cedar Hill, TX uses Nexedge.

Yes, I did mean a BCD99XT

Right now we have a Uniden SC150B with the stock rubber duck antenna. We soldered in a discriminator, but I think we have had pretty horrible reception with the stock antenna. I'm not sure if this radio is even capable of getting the frequencies from the 3 cities. I have no problem running it through the linux Digital Voice Decoding Software, but just question the capabilities of this scanner. It does have a removable antenna (looks like an old school network BNC connector for computer networks) where I could install an external antenna to it.

If needs be, I also don't mind purchasing a new scanner... But I'm always willing to use the one I have if possible. I do want another antenna.

I just figure this is the perfect hobby for my son and I to get into together.
 

ka3jjz

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Well if it were me, I'd improve the antenna on the SC150 and see if the discriminator tap is giving enough signal that DSD does its thing. I'd get another scanner for everything else. I would also go to the Texas forum and see what folks are using in your area - while the 996XT (heh, my 6 key is working...) is a nice radio, there are several other digital trunktrackers. Get your recommendations from local users - they're going to be the best ones to guide you.

A short duckie at 400 mhz is OK, but nothing to write home about. I have no doubt that the stronger and cleaner the signal, the better the decode works. Heck, even a UHF ground plane mounted nice and high would likely outperform an indoor duckie by a wide margin. There are LOTS of places to find plans to build one on the web...a few of which can be found in our scanner antennas wiki

Scanner Antennas - The RadioReference Wiki

Remember that just because the plans are for, say a VHF ground plane, the math for making it work on the UHF band is trivial (even a caveman can do it, hi)

Since this discussion is a bit OT, I'll leave it there...you know where to go for more information...best regards..Mike
 

yeshuaisiam

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Okay... I had another question...

Are digital signals transferred through actual packets similar to networking? I'm curious because it would be of interest in me with heavy wifi experience of the encryption methods used. As we know wifi signals are basically brute forced through weak IV packets, and I'd be curious if some of the manufacturers of the encrypted radios use the same chipsets as they do in wifi routers for their encryptions. Would be very interesting if they used WEP or WPA for their digital encryption. (If encryption is often used I do not know).

Are there scanners that would work to allow dumps into a computer I/O port (like some kind of data terminal?) that could help me look at the raw encrypted packets (if they work like that).

Would be monumental to DSD (I'm sure) if there was also a way around the encryption. Should be legal so long as scanning.
 

Comint

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. . . and I'd be curious if some of the manufacturers of the encrypted radios use the same chipsets as they do in wifi routers for their encryptions.
Look up AES - Advanced Encryption Standard - for the type of encryption used on radios. Far superior to the 'wimpy' WEP/WPA.



Are there scanners that would work to allow dumps into a computer I/O port (like some kind of data terminal?) that could help me look at the raw encrypted packets (if they work like that).
The Uniden BCD396XT, and some of the GRE scanners have a Data port, but I don't know if they pass the raw encrypted packets.

--
Comint
 

yeshuaisiam

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Look up AES - Advanced Encryption Standard - for the type of encryption used on radios. Far superior to the 'wimpy' WEP/WPA.




The Uniden BCD396XT, and some of the GRE scanners have a Data port, but I don't know if they pass the raw encrypted packets.

--
Comint
Just so you know, the WEP was pretty weak, but the WPA & WPA2 uses AES by itself, TKIP + AES, and sometimes adds CCMP to it. Very encrypted.

The interesting side of this to me would not be the encrypted voices, but dumping some of the control channel (if it is encrypted). In many routers, the chipsets are made with WRT standards.

Just a very extremely pre-mature (probably more hypothetical than hypothesis) but I'd be curious to run some of the brute force techniques used against AES packets from the radios. The nice thing with radios especially with cities PD/FIRE etc., is that they use them frequently. That way the server/client or host/client often has communication. That's one of the essentials is to get any form of handshake packets collected.

Now, with that said, It would be HIGHLY illegal to inject fake packets into the radio stream, which is sometimes the process of getting wifi handshakes (fake client disconnect packets injected). But like I said, the city workers key up a lot, which would most likely generate these handshakes that are needed.

Thanks for the radio suggestion. I'll look into it. Hopefully it will let me collect raw data / raw data encrypted packets. I'd need full dumps to analyze. The trick here is to remain legal on ONLY use RX and never any TX for injection. May be a much longer brute force technique.....

Either way it would be great to generate some methods to get past encrypted radio signals for our listening pleasure. :)
 

fwradio

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If they are using encryption on that system, it is a weak encryption. Be warned, you can open up a big can of worms if you have the ability and actually do find a way to bust the encryption. There are only 32,767 keys so it might not be too hard to figure out. But actually listening to encrypted communications is a big no-no.
 

yeshuaisiam

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If they are using encryption on that system, it is a weak encryption. Be warned, you can open up a big can of worms if you have the ability and actually do find a way to bust the encryption. There are only 32,767 keys so it might not be too hard to figure out. But actually listening to encrypted communications is a big no-no.
Okay, I was not aware that this was actually wrong to do. (legally?) As far as I understand that we are allowed to receive any radio signals on our property unless it is a pay service (such as satellite TV or radio) since this is a pay for service.

As far as police radio is concerned I wasn't aware that it would be illegal to listen to any encrypted services because they are not a pay for service, but more or less just like monitoring.

I'm trying to find actual laws about this. Thanks!
 

nd5y

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Here are the main two laws regarding intercepting communications:

18 U.S.C. §§ 2510, 2511, 2512
Title 18 United States Code Part I Chapter 119 Sec. 2510-2512
(WIRE AND ELECTRONIC COMMUNICATIONS INTERCEPTION AND INTERCEPTION OF ORAL COMMUNICATIONS)
United States Code: Title 18,2510. Definitions | LII / Legal Information Institute

47 U.S.C. § 605
Title 47 United States Code Chapter 5 Subchapter 4 Sec. 605
(Communications Act of 1934)
United States Code: Title 47,605. Unauthorized publication or use of communications | LII / Legal Information Institute

If you search for "encryption" on the right where it say s U.S. Code Toolbox
Search this title:
you get 24 hits. I didn't check to see if the others were relevant.
 
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Radioman96p71

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For what its worth, 2-way radio encrypted comms are barely similar to the way wifi works. (with the exception of OpenSky that uses a handshaking operation to establish a keypair)

Aside from that, most digital voice like AEGIS, ProVoice, P25, NexEDGE, MotoTRBO, VSELP etc use a static key that is never changed unless all the radios are re-keyed. Because of this, there is no handshaking or key exchange over the air. If the radio has the right key, it will decode the stream and you will get voice, if not you will get nothing or R2D2.

Another limiter is the MUCH narrower bandwidth used in 2-way vs WiFi. With such limited data rates, efficiency is of utmost importance. Every bit has to count. So you wont see a lot of 'wasted' data for key synching or the like. The best you will get over the air is the IV bytes in the header.

Granted DES is a considerably weaker encryption method than AES, it still leaves a huge hurdle of actually capturing good data (and having a way to verify it is, in fact, good) figuring out the exact method of encryption and then coding the software to replicate what the radio DSP does. Once you do all that you only have a few trillion keys to try! And you better hope they don't switch them on you later.
 

yeshuaisiam

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Good Scanner for DSD (trunk) for NEXEDGE

Hi!

I'm pretty much between a beginner and novice in radio skill. I scanned "back in the day" when PD's really didn't use trunking. So I basically know what a band is, frequency, and trunking (for the most part anyway). I also understand fairly well what a digital signal is. Anyway I'm really trying to look for a scanner that I can enjoy with my sons. I'm fluent enough in Linux and have installed the DSD software and have no problem using it. Also I think I can handle a discriminator just fine.

(I've tried asking the the Texas forum but was referred here.)

My local PD uses NEXEDGE. My "locality" is actually 3 cities that use the same dispatch. Cedar Hill, Duncanville, and Lancaster, Texas.

We plan on using the DSD software 100% of the time as we enjoy the combination of computers and radios.

I'm just looking for good suggestions of what scanners to get. Can I just get a good analog trunking scanner and use the DSD with it or would it be better if I just went digital while I am at it?

Our primary purpose (other than just spending good time together) is to listen to the PD, Fire, local fast food (my sons would crack up laughing at people's orders), and just general other stuff like aircraft or whatever.

Used, New, doesn't make a difference. Of course cheaper is always better, but we could also spend a buck if needed. Again, DSD could be used ALL the time. It will be a 100% base scanner.

Also antenna suggestions?

Thanks so much guys. Sons are 10 and 7 and just trying to get them into a fun hobby that I can enjoy with them. (educational too)
 

Radioman96p71

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I think im having deja-vu...

Scanner can be as simple or elaborate as you want. Luckily a lot of analog scanners like the robust BC780XLT and Pro2052 can be found on ebay pretty cheap. If you want a scanner that can do its own P25 decoding (not sure if that even applies to your area) you would want one of the latest ones, which will demand a much higher price. Again, its whatever you want to spend. All are roughly equal as far as adding a descriminator tap goes, unless you get into the super-high-end stuff that already has a tap anyways.

An antenna is a very hard thing to suggest without a LOT more info. What is your dwelling like, can you put anything on the roof, can you drill any holes, are there any housing restrictions, large attic to hide an antenna, etc etc. Just a wild guess that you might be able to put a tripod on the roof, i would suggest a simple Discone antenna, they are extremely wide-band and work for a wide variety of things. If you will be monitoring one band only you may want to invest in a gain antenna for that specific band to improve signal strength. There are a TON of variables here, going to need a lot more specifics if you want a more precise answer.
 

yeshuaisiam

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I think im having deja-vu...

Scanner can be as simple or elaborate as you want. Luckily a lot of analog scanners like the robust BC780XLT and Pro2052 can be found on ebay pretty cheap. If you want a scanner that can do its own P25 decoding (not sure if that even applies to your area) you would want one of the latest ones, which will demand a much higher price. Again, its whatever you want to spend. All are roughly equal as far as adding a descriminator tap goes, unless you get into the super-high-end stuff that already has a tap anyways.

An antenna is a very hard thing to suggest without a LOT more info. What is your dwelling like, can you put anything on the roof, can you drill any holes, are there any housing restrictions, large attic to hide an antenna, etc etc. Just a wild guess that you might be able to put a tripod on the roof, i would suggest a simple Discone antenna, they are extremely wide-band and work for a wide variety of things. If you will be monitoring one band only you may want to invest in a gain antenna for that specific band to improve signal strength. There are a TON of variables here, going to need a lot more specifics if you want a more precise answer.
Bah, sorry about that, no Deja Vu, just posted on this thread and meant to post on a different forum :eek:)

I can put up an outdoor antenna in my neighborhood. Tripod would work fine unless there are better options. We just want to scan, but the PD is the most important.
 

Forts

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Just curious.... but aren't mos NXDN systems (especially for public safety) encrypted? All the radio shops around here somewhat brag about NXDN being more secure than MotoTRBO as it is encrypted all the time. I'd hate to see folks get too deep into a setup only to find out everything is ENC.
 

hawk777

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nexedge DSD

Any luck decoding nexedge? I undestand you have heavy lunux experience, I have experience as a two way radio/scanner tech for any mods or info you might need as far as IF/discriminator taps, etc.

Regards
 

ab3ai

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Just a thought. If what I was looking is correct, the system is trunked. There is no program that I'm aware of that will track NXDN control channels. Also, make sure that the baud rate is correct. Kenwood uses 4800 and 9600 in there radios. DSD will decode both baud rates. You may have to adjust your levels to ~30 percent.
 

hatzolahCW

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NY
Decode NXDN

Hi,
My local PD just switched to NXDN 6.25 (NXDN4800) Trunking system with encryption.
im listening to them for almost 15 years and it just stopped from one minute to the next...
im dying to hear them but from my research it sounds that there is no way...
is there anyway to decode it?? iil do whatever it takes!!....
 
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