Using a Motorola P25 radio as a scanner.

[GTR8000]

No night on RR would be complete without a pointlessly heated debate over something that was settled long ago! 😂

 

[ElroyJetson]

As for the TX inhibit, have you checked it using the test conditions I described earlier? It may be that the Astro Saber had a firmware version that allowed affiliation to occur while inhibit was selected. I know what I experienced. I even wrote it down, in a notebook that I've long since lost.

I don't dispute that current generation radios don't suffer from that "issue".

 

[chrismol1]

Yes I believe it was possible the early 20+ year old astro firmware had issues with the tx inhibit. No latest Astro25 XTS or APX portable has had since 20 years ago. I'll add some 2 cents to this thread to confirm that using unitrunker, SDRTrunk, a radio specifically parked on the control channel input, that TX inhibit by switch position and menu item will not allow any RF transmission. But we'll reconvene here in a few months to hash it out again

 

[mikewazowski]

Setting a switch to tx inhibit will prevent all transmissions *and* setting the ignition line on a mobile radio to tx inhibit will also prevent all transmissions. I used to have an Astro Spectra in my vehicle with a switch connected to the ignition line so I could still use my radio on Amateur and commercial frequencies and still safely monitor a trunking system when I wanted to. Was doing it on an Astro Saber as well.

As far as who invented NAS, a bunch of us were doing it a long time ago. I’ll give Elroy credit for his great write up and the decision to hide the trunking channels on a portable beyond channel 16 though. However to claim he invented it is a bit of a stretch when it can’t be proven.

 

[GTR8000]

As for the TX inhibit, have you checked it using the test conditions I described earlier? It may be that the Astro Saber had a firmware version that allowed affiliation to occur while inhibit was selected. I know what I experienced. I even wrote it down, in a notebook that I've long since lost.

I don't dispute that current generation radios don't suffer from that "issue".

At some point you need to leave the distant past in the past. The Saber is a 30+ year old radio, and I doubt there are many still using one to monitor modern day trunked systems. Even the ASTRO 25 series (XTS/XTL) are long in the tooth, with the XTS 5000 first introduced in 2000 and having been canceled nearly a decade ago.

Instead of dredging up obscure examples from decades ago, how about we focus on the radios the OP actually mentioned? The XTS 2500 and XTS 5000 operate exactly as I describe as pertains to the TX Inhibit function. Some of you are getting the TG/AG Disabled (i.e. listen only) feature confused with the TX Inhibit, and you're making false claims based on a misunderstanding of these separate features.

 

[ElroyJetson]

I may not have been the first person to figure it out...but so far as I know I was the first person to publicize it on the forums.

Fair enough?

Really it wasn't that hard to figure it out. Anybody who knows how to program Motorola trunking systems into radios, and who also wants to listen without formal approval, would eventually start trying to figure out how to break the transmit ability while keeping the receive ability.

When you seek long enough, and hard enough, eventually you will find an answer. When I learned that conventional channels can have mode slaved scan lists that contain trunking groups, it didn't take very long for the little light bulb to come on.

That was the first piece of the puzzle. And when I made a mistake and forgot to include the CHAN menu selection in my radio and could thus not access channels 17 and above in a zone I'd created that contained ALL the VHF marine channels, that gave me the last piece I needed.

I was more than happy to write it up and publish it to the Batlabs forum. Happy to share it. Because I want us to be able to scan in perfect safety and NOT interfere with the systems being scanned.

 

[merlin]

If you are even capable of affiliating, you did it wrong. If you programmed it correctly, there is no way to cause it to affiliate even if you wanted to, because the channels that would affiliate are completely inaccessible from the knob and keypad. The trouble, as always, is that preface "if you programmed it correctly...". That's where all the trouble is.

If you are programming an XTL5000 for P25 it MUST sit on a site control channel and scan all the talk/data channels OR it wont work.
YES, you can program your desired talk channels as conventional and selecting any won't affiliate.
The problem is those site voice channels must also be programmed to tie to the conventional channels.
If you are very careful, you can select any of those conventional channels and you are good to go.
You cannot keep any channel selection restricted above those conventional channels.
Say you program the bottom 12 channels as conventional. Throw in a blank or two. The talk channels MUST be programmed above that.
Channel up or rotary channel select DOES NOT stop with conventional. Select 13 or 14, the radio boops, select channel 15 and you have bypassed channel 1 conventional and WILL try to affiliate. It will get denied anyway unless your radio ID is acknowledged by the system.
You can continue up to the max channel in programming.
It is just too easy to select a channel that is not conventional.
Don't believe me,,try it.
Now this all applies to the XTL5000 700/800 radio with W7 head.
""channels that would affiliate are completely inaccessible from the knob and keypad""
That is where you are wrong. the XTS is the exception.
Cheers

 

[merlin]

I've never used an XTL, but that's an interesting caveat. And a reason why NAS is even more dangerous than I thought. If you can't have the confidence that so long as you program it right you simply cannot affiliate even if you wanted to, then "that's a 'no' for me, dawg."

Others have used dummy channels above what is needed, so scrolling into those, the radio BOOPS to let you know you have gone too far.
If one is careful, it is not much problem. My mod makes it idiot proof. What you have now is a nice scanner, not a tranceiver.

 

[ElroyJetson]

Remember, this method was developed primarly for portable radio usage. All Motorola public safety portable radios are limited to 16 channels on the rotary knob. That doesn't apply to mobile radios, at least not with the control heads I'm familiar with.

You are not the first person to disable the transmitter out of an abundance of caution. I've removed a PA driver transistor before, sure. And taped it to the inside of the cover so it can be reinstalled later if need be.

I do not see why an XTL5000 would have to sit on a control channel for scan to work, when that's not a requirement for an XTS5000, as is well proven. While I do not know the internal logic path that the radio follows when scanning trunked systems via trunked members of a scan list being referenced from a conventional channel. , it DOES work.

However I have no hands on experience with the XTL platform. Seems strange to say it, but I've always focused on portable radios to a much greater extent than mobiles.

The last time I had a Motorola mobile radio installed in a vehicle it was a high power VHF Spectra, not even an Astro Spectra, with either an A4 or A7 control head. (I'd bit bang them as needed if I wanted to switch head types.)

I'm WAY behind the power curve on modern mobile radios, that's for sure!

 

[rescue161]

Yes, you can use an XTL5000 for NAS and have the trunked talkgroups inaccessible. It has been described in detail on this very thread. No need for a 16-channel detent restriction. You just have to change your thinking in the way you program. You put the conventional and trunked talkgroups in different zones and remove the ability to change away from the conventional zone. You'll only have one zone, but you can have way more than 16 channels in that one zone.

 

[clbsquared]

If you are programming an XTL5000 for P25 it MUST sit on a site control channel and scan all the talk/data channels OR it wont work.

No, you don’t have to park it on a control channel. You can park it on 136.00000 or any other conventional analog frequency and it will STILL work. Remember..... you are slaving a trunking scanlist to a conventional personality. It doesn’t matter what frequency you use for the conventional channel. And honestly, it should be as far away from any control or voice channel frequency associated with the trunking system.

 

[ElroyJetson]

The great thing about other band trunking (UHF or VHF) is that you can skip all that noise and just program it as a straight trunking radio, no mode slaved scan required, and just intentionally goof up the TX offset setting. The odds of anybody intercepting the short data bursts that are the radio asking to affiliate to the control channel, which isn't even listening on that frequency, are remote. But do your due dililgence and try to check all the frequencies that the altered offset causes the radio to try to send data bursts on, just as a matter of prudence.

This does cause brief transmissions to occur which technically are illegal but they're data bursts that are milliseconds long. They'll go unnoticed nearly all the time. But it simplifies the programming.

My story regarding radio waste: The local Air Force Base was running their base trunking system in the 403-430 MHz frequency range. Using XTS5000s, XTL mobiles, and Quantars at the sites. The decision was made to migrate to P25 trunking.

They migrated to the 380-400 frequency range. And....replaced every UHF Range 1 XTS5000 with a brand new UHF Range 1 XTS5000 with P25 trunking. Same for the mobiles. Same for the repeaters.

Yeah...they forklift upgraded a system that could have been Flashport upgraded.

Your tax dollars at work!!!

 

[cpetraglia]

Very true, but getting that "right" (old!) firmware and CPS for the Harris - especially through "legitimate" channels - is neither easy nor cheap. BK, on the other hand, will gladly sell you a copy of their programming software for a relatively reasonable price and current (free) firmware has the RX Only feature.

Although I'm a fan of BKRadios for high-quality P25 scanning, to prove that I'm not willfully blind to the pros/cons here I will add this: The BKRadios do NOT let you scan multiple trunked systems at the same time. Motorola radios, using the ElroyJetson NAS method, do. That's the biggest downfall to the BKRadios - easier to get, easier to program, safer, more legitimate, etc., but you can only scan TGs from one system and one site at a time.

I was so impressed with my P800 radio, that I bought two more. Now I can scan multiple systems at once. Also, I was lucky enough to find 2 BK KNG800s on Ebay for $1500.00 each. They came from China, so I was skeptical. Both had the additional programming for P25 and PII. I used the PayPal payment plan so I would be covered if I got shafted. Both worked perfectly and still are 4 years later.

 

[DanRollman]

I was so impressed with my P800 radio, that I bought two more. Now I can scan multiple systems at once. Also, I was lucky enough to find 2 BK KNG800s on Ebay for $1500.00 each. They came from China, so I was skeptical. Both had the additional programming for P25 and PII. I used the PayPal payment plan so I would be covered if I got shafted. Both worked perfectly and still are 4 years later.

I run two KNG2-P800 radios in the car, and two KNG-P800s in the office, in order to truly listen to two things at once. Not quite the same as being able to scan two or more sites or systems at once with a single radio, though, especially if they just aren't busy. For example, I'd love to be able to scan just the fireground channels on 4 or 5 systems so that the radio sits silently until there's a working fire somewhere.

 

[ElroyJetson]

I live fairly close to the BK radio factory in Melbourne, Fl. (Formerly Relm, formerly Regency.) They've always had their portable radio products built, at the board level, by factories in other countries. They get the preassembled boards in case lots and then add the casework to them and finalize them for sale. At least that's how they always did it in the past. I believe they still do, but can't say that with absolute certainty.

I do know that back in the days of crystal controlled radios, I saw some disassembled radios from other brands (Yaesu being one....) that had exactly the same circuit board in them as certain Regency/Relm radios. Boards I knew quite well.

We've all seen Motorola radios from China, too. It may well be that the circuit boards for even APX radios are built in China and shipped to the US for final assembly. I would not be surprised.

 

[GTR8000]

The great thing about other band trunking (UHF or VHF) is that you can skip all that noise and just program it as a straight trunking radio, no mode slaved scan required, and just intentionally goof up the TX offset setting. The odds of anybody intercepting the short data bursts that are the radio asking to affiliate to the control channel, which isn't even listening on that frequency, are remote. But do your due dililgence and try to check all the frequencies that the altered offset causes the radio to try to send data bursts on, just as a matter of prudence.

This does cause brief transmissions to occur which technically are illegal but they're data bursts that are milliseconds long. They'll go unnoticed nearly all the time. But it simplifies the programming.

More outdated/invalid advice. Let's put aside the illegal transmissions factor and focus only on functionality...or lack thereof.

If you program a P25 system by fudging the control channel inputs and TX offsets in the ASTRO 25 Channel ID table, the radio will display NO COMMS and will not open up for any traffic.

An MSI subscriber (XTS/XTL/APX) needs to successfully register and affiliate before it will pass any traffic if you are parked on a trunked talkgroup.

Your "trick" may work for older 4.x SmartNet/SmartZone (aka Type II) systems, but it does not work on P25 systems.

 

[natedawg1604]

I run two KNG2-P800 radios in the car, and two KNG-P800s in the office, in order to truly listen to two things at once. Not quite the same as being able to scan two or more sites or systems at once with a single radio, though, especially if they just aren't busy. For example, I'd love to be able to scan just the fireground channels on 4 or 5 systems so that the radio sits silently until there's a working fire somewhere.

What is the scan list capacity?

 

[mikewazowski]

If you program a P25 system by fudging the control channel inputs and TX offsets in the ASTRO 25 Channel ID table, the radio will display NO COMMS and will not open up for any traffic.

An MSI subscriber (XTS/XTL/APX) needs to successfully register and affiliate before it will pass any traffic if you are parked on a trunked talkgroup.

Not only that, on older systems you’ll experience holes in the audio and missed calls while your radio is trying to affiliate plus on a portable, you’re going to chew up your battery very quickly.

 

[GTR8000]

Not only that, on older systems you’ll experience holes in the audio and missed calls while your radio is trying to affiliate plus on a portable, you’re going to chew up your battery very quickly.

Yup, that too! An XTS/XTL setup that way with SmartZone coverage disabled will constantly and ruthlessly try to register on the system. The APX is a bit less ruthless, but will still try to register frequently. None of that behavior is desirable, even if the radio is transmitting on a BS frequency.

Just program the radio the correct way using the well documented non-affiliate scan method. Or buy something besides a Motorola radio to scan these systems...a lot less hassle and gray area that way.

 

[ElroyJetson]

Good to know. I wasn't aware that OBT P25 would not work properly with an incorrect TX offset. Never actually tried it.

There is an OBT Phase 1 trunking system in range of me. But I seem to be unable to find my UHF XTS5000. I know it's here somewhere...but I have radios scattered all around the house.