Federal NAC codes

[Armadillo5]

Thank you for the help.

What I am refering to is this,,,,,if I program in let's say customs main channel and it is analog and then I program in the pl tone for that channel, if they go encrypted I will not hear the "white noise" accompanied by the use of encryption. The pl tone will block it.

With p-25 how do I do the same thing by using NAC codes and listening to them on a p-25 channel when they go encrypted so I can block the "white noise" and only hear the "clear" transmissions?

To me, I would think that there is a way for me to hear them when they are in the "clear and when they go encrypted, then the NAC would "block" the "white noise" until they are "clear" again.

Make sense?

 

[Wayne]

With p-25 how do I do the same thing by using NAC codes and listening to them on a p-25 channel when they go encrypted so I can block the "white noise" and only hear the "clear" transmissions?

To me, I would think that there is a way for me to hear them when they are in the "clear and when they go encrypted, then the NAC would "block" the "white noise" until they are "clear" again.

Make sense?

To do what you describe, program the receive mode as "digital". Select the Rx squelch type as "normal". Program the correct Rx NAC. This way the radio will ONLY unsquelch if a transmission is unencrypted and matches the programmed NAC. If you program a switch or menu item with "pl defeat" it acts as digital csq and you will hear all digital transmissions including encrypted on that frequency. You can toggle back and forth at the flip of a switch...

Wayne

 

[Armadillo5]

So this "switch" within the radio, does one exist within a VHF Astro Saber so I can use the "pl defeat" feature within my VHF Astro Saber?

This sounds like a nice feature to have and use.

Thank you for writing the latest post and clearing things up. I will give it a try.

 

[Wayne]

It depends on your exact radio flash but I think PL Defeat is pretty much a standard switch/menu option. I use it with an Astro Saber on the A/B switch. By the way, if your Astro is flashed for digital id display, your radio will unsquelch with the correct NAC and you will see radio id's on the display.

Wayne

 

[Armadillo5]

What do you mean by "the radio will unsquelch" with the correct NAC and I will see the id?

I have a VHF Astro Saber 3 with full digital and analog spec's.

 

[mbstone99]

NACs

What do you mean by "the radio will unsquelch" with the correct NAC and I will see the id?

I have a VHF Astro Saber 3 with full digital and analog spec's.

I think that what he means is that it's the same concept as how PL/DCS works.. say you put in a frequency into a radio with a PL or DCS tone. If someone else transmits on that frequency with a different PL or DCS tone you won't hear the conversation. Now if someone transmits on that frequency with the PL or DCS tone you have programmed the radio will "unsquelch", the radio will see that its the right PL or DCS tone and allow you will hear the conversation. Well NAC's are the same way but work in the P25 world and not the analog world.. I hope this helps.

Matt

 

[Wayne]

What do you mean by "the radio will unsquelch" with the correct NAC and I will see the id?

I have a VHF Astro Saber 3 with full digital and analog spec's.

We are getting way off topic here. Contact me offlist and I will elaborate.

A few more Fed NAC's I have logged;
DOE - NAC 500
Reserve Bank - NAC 293
Fed Courthouse - NAC 293
Postal Inspectors - NAC 482
ICE - varies, each repeater different

Wayne

 

[WayneH]

What I am refering to is this,,,,,if I program in let's say customs main channel and it is analog and then I program in the pl tone for that channel, if they go encrypted I will not hear the "white noise" accompanied by the use of encryption. The pl tone will block it.

You can't use a NAC to block encryption like you can with a tone. Digital is different because of how it is structured. A NAC is always sent because it falls in the background CAI whereas the voice is within a different area of the data and can be encrypted or clear voice without affecting the CAI information.

 

[Armadillo5]

So now I am cofused....This is fun!

I see one person has written one thing and another person has written another thing.

So I have to ask, can a NAC be used like a PL Tone to block encryption when encryption is being used?

Or, is there a "special setting" within the Astro Saber that can be used to allow the radio to open up when encryption is not being used but still get rid of the "white noise" when encryption is being used?

So far this discussion to me is good for one main reason, "a better understanding of NAC's and how they are used".

No I am not frustrated about what has been written, just looking for a "clear" understanding of NAC's.

Thank you for the help.

 

[mbstone99]

NACs

So now I am cofused....This is fun!

I see one person has written one thing and another person has written another thing.

So I have to ask, can a NAC be used like a PL Tone to block encryption when encryption is being used?

Or, is there a "special setting" within the Astro Saber that can be used to allow the radio to open up when encryption is not being used but still get rid of the "white noise" when encryption is being used?

So far this discussion to me is good for one main reason, "a better understanding of NAC's and how they are used".

No I am not frustrated about what has been written, just looking for a "clear" understanding of NAC's.

Thank you for the help.

As Wayne said in his post just before your post.. no you can't use a NAC to block encryption.

Matt

 

[mikewazowski]

Anybody's head getting sore?

Remod, as has been said many times before, you cannot use the NAC to block out an encrypted signal. NAC's have nothing to do with encryption. You cannot draw a parallel between analog ctcss tones and NAC's when it comes to encryption. Analog CTCSS tones are not transmittable across encryption but NAC's are. That is why you can't do what you want to.

To block an encrypted signal, you need to do as com501 stated and have your radio only unmute on the correct encryption key being received.

Look through your RSS/CPS menu's in the Encryption Configuration screens and you'll see the option.

 

[10-95]

Look for "Proper Code Detect" and check that box.

 

[Armadillo5]

Again, thank you for the help and understanding. Sorry to make your "head sore" but that was not the intention. Sometimes I may ask or re-ask a ? to make sure I understand.

Most people I have talked with [not on this website] have "no real understanding of NAC's" and how they are used. I have seen in other posts and on the "Database" where NAC's seem to be popping up all over when these "new digital systems" come into use. Some have said, "a NAC is just like a PL Tone". Others have said the opposite.

I have been VERY confused on this issue and was just looking for some help to program my VHF Astro Saber in the best way possible. I like others do not like the "white noise" that comes on the radio when encryption is being used.

I will try some of these suggestions.

Again I appreciate the help and thank you for the responses.

Best regards.....

 

[mancow]

You keep mentioning white noise. If it's encrypted P-25 digital then it should sound like garble, like a bad nextel connection. If it truly sounds like white noise like a hash or open squelch static then it's an analog DES Securenet type of encryption and a NAC won't apply.

You probably know all this alreay but I figured I would mention it.

 

[Audiodave1]

TSA uses NAC 001 most places with 002 possibly being the code for supervisors or something of the like.

Dave

 

[JASII]

I just found this thread by searching. Thanks to those that have already posted. If I get the forthcoming GRE PSR-500 or PSR-600 and were to program in the federal bands with NAC $293 on every frequency, I will receive ALL P-25 activity on the frequencies regardless on NAC codes? And, assuming that Butel or others have software for this, the history log could show active frequencies. I am guessing that running with a NAC code that I shouldn't get many false hits from front end overload, mixing, images, etc.

Also, do I understand correctly that talkgroups are also possible on conventional P-25?

For the Minnesota listeners, has the U.S. Army Corps of Engineers made the switch to P-25 already? If so, did they use the same frequencies? What about the Saint Croix National Scenic Riverway? Are they now P-25? Did they use the same frequencies?

 

[WayneH]

I just found this thread by searching. Thanks to those that have already posted. If I get the forthcoming GRE PSR-500 or PSR-600 and were to program in the federal bands with NAC $293 on every frequency, I will receive ALL P-25 activity on the frequencies regardless on NAC codes?

No, you would be blocking all NACs except $293. $293 is the default NAC since P25 conventional must sent a NAC in the data. Even when a repeater is setup for what's called DCS (digital carrier squelch) a NAC ($293) is still sent.

You'll have to turn on tone search to determine the NAC first, and then store it.

 

[code3cowboy]

So if I understand this correctly, I have to have the correct NAC programed in my Astro Saber in order to hear let's say the ATF? Or, I have to have the correct NAC programed in to break the squelch?

I have one of their channels plugged in and the only way to hear it is when I open up the squelch on the radio using the button on the side of radio.

Thank You for the help.

Nope, just to talk to them.

 

[freqhopping]

Tapped my BC890 and using KNACK I've been decoding some NACs in the DC area.

Shenandoah National Park 4F9
Postal Inspectors 482
Federal Protective Service 402
State Department Security 0F0

Got another Sunday night, ICE at Dulles airport is 079

 

[wwhitby]

The Montgomery, Alabama VA Hospital is using 293 on both its repeater input and output frequencies.

Warren