Passively scanning Astro25 trunking systems

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Passively scanning Astro25 trunking systems

Post by VE9MP » Wed Aug 15, 2007 12:33 pm

Firstly, please no bullshit, save it for someone who gives a damn..I am asking a purely technical question for the sake of curiousity...

The province here has finally put out thier Request for proposals on a new radio system...

The system is going to be trunked, P25 compliant, which I assume they mean full Astro25 with 9600 baud control channels...

Its going to be either one of 3 choices...
60 site VHF Trunk system, with 2 VHF analog/conventional layers for two-tone/voice paging and interop repeaters

80 site UHF 450MHz trunking system, with 2 VHF analog/conventional layers for two-tone/voice paging and interop repeaters

115 site 700 MHz trunking system, with 2 VHF analog/conventional layers for two-tone/voice paging and interop repeaters...

Now...I will be an authorized user of the system anyways...but what options are there for monitoring talkgroup udio without affiliating... like Elroys "hidden talkgroup" method, or does the radio need to successfully affiliate in order to receive talkgroup audio? Just curious as to what others are doing to monitor Astro25 systems..

No, I will not buy a scanner...
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Re: Passively scanning Astro25 trunking systems

Post by 10-95 » Wed Aug 15, 2007 12:43 pm

VE9MP wrote:Firstly, please no bullshit, save it for someone who gives a damn..I am asking a purely technical question for the sake of curiousity...

The province here has finally put out thier Request for proposals on a new radio system...

The system is going to be trunked, P25 compliant, which I assume they mean full Astro25 with 9600 baud control channels...

Its going to be either one of 3 choices...
60 site VHF Trunk system, with 2 VHF analog/conventional layers for two-tone/voice paging and interop repeaters

80 site UHF 450MHz trunking system, with 2 VHF analog/conventional layers for two-tone/voice paging and interop repeaters

115 site 700 MHz trunking system, with 2 VHF analog/conventional layers for two-tone/voice paging and interop repeaters...

Now...I will be an authorized user of the system anyways...but what options are there for monitoring talkgroup udio without affiliating... like Elroys "hidden talkgroup" method, or does the radio need to successfully affiliate in order to receive talkgroup audio? Just curious as to what others are doing to monitor Astro25 systems..

No, I will not buy a scanner...

"This is why we tell people to buy a bla, bla bla! " Just kidding! Anyway, it will depend on the radio. It's more do-able with a XTS3000, it 's possible on a 5000 but there is a trick or two involved with using a 5000 to passively monitor. r0f, where are you??

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Post by exkalibur » Wed Aug 15, 2007 9:28 pm

Just to add to r0f's post...

When you say the "above 16" thing for talkgroups you want to RX but not affiliate on, I assume you mean on a 3600bps system? If so, you don't need to do the "above 16" thing. Here's what I've seen done and it works flawlessly.

First, program both positions of the concentric switch to TX Inhibit.
Then, program the systems' coverage type to "Disabled" or "None" (IE, Smartnet). Then Affiliation on PTT.

This will ensure that NO transmissions of any kind will come from your radio. Even requests from the system to affiliate won't cause the radio to TX. If you REALLY want to make sure, hook your radio up to a service monitor and adjust TX Power until nothing comes out. You can't stop it 100%, but you can reduce it to the point that a radio 2 feet away won't detect anything.

The above will work on an XTS3000, Astro Saber, and the MTS2000 series.

Let's say you want your radio to be able to TX on some conventional channels but not on trunking.

Do everything I mentioned above (except for the TX power adjustment) but in addition, program a menu option for TX Inhibit, but ONLY put this menu option in the Conventional menu and not the Trunking menu. This way, when you are in a trunking mode, there's no way to have turn on transmit, but if you switch to a conventional mode, the TXIN menu option comes up and you can enable it. There's one catch to this. If you switch back to a trunking mode BEFORE you turn TX inhibit back on (by flicking the knob), the radio will be fully capable of transmitting on that trunking mode (including affiliations and all that).

This works because the radio only polls the switch position when you change it. IE, because both positions are TX Inhibit, the radio will always be in TX Inhibit, regardless of the position of the switch. Now, when you turn TX Inhibit off in a menu, the radio doesn't re-poll the concentric switch because you haven't adjusted it yet. So the radio will then TX. This is why it is important to flick the switch before you switch back to a trunking personality.

This works just fine on VHF, UHF and 800MHz trunking systems. It also works just fine when the radio is programmed as SmartZone (so you can take advantage of the radio's ability to select the most appropriate site) - obviously you have to hope your talkgroup is being transmitted on whatever Zone the radio selects for this to work.

If you're really paranoid and worry about someone finding out that your radio has the local Police talkgroups in it... Program a zone in your radio with ONLY conventional channels. Then disable the Zone selection in the conventional menu (but keep it in trunking). Then, add a 17th channel to your zone called TRUNK REVERT or something, that is a BS trunking personality. Then in the conventional menu, enable the CHAN selection, allowing you to change to channel 17 in that zone. Then you would program your HOME button to select a conventional channel in that zone. That makes it impossible to move out of that conventional-only zone unless you manually "channel up" to the TRUNK REVERT channel and change zones to another zone with trunked channels in it.


Sorry if this was off topic, but I've seen quite a few posts on how to make your radio not TX - this is bar none the most effective way I've ever seen. I've been fortunate enough to be able to test this on a system where we were able to use a console and System Watch to bombard the radio with every kind of request we could (IE, Inhibit, Snapshot, Private Call, etc...) and nothing we did made the radio transmit (or even attempt to) while in the TX Inhibit mode.
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Post by VE9MP » Wed Aug 15, 2007 9:29 pm

Thanks Shaun...
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Post by exkalibur » Wed Aug 15, 2007 9:32 pm

One word of caution with this "hack".

It will not work on an MTX8000/MTX838.

If you set both positions of the concentric switch to TX Inhibit, the radio will still respond to system messages.

However, if you "convince" an MTS2000 codeplug into the radio, then it will work fine.

I'm not sure what the difference is between the two, but just be warned if your radio turns into a brick!

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Post by exkalibur » Wed Aug 15, 2007 10:31 pm

I have 07.22.01 and I can assure you more than anything that an 800MHz Astro Saber (and an 800MHz XTS3000) programmed for Smartzone with TX Inhibit turned on WILL RX without issue. This is with Omnilink disabled. I've never tried with it enabled.

I wish there was some way I could show you that it works. It also works just fine on an Astro Spectra with new firmware (not sure what version, but fairly recent).
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Post by ka8ypy » Wed Aug 15, 2007 10:40 pm

exkalibur wrote:I have 07.22.01 and I can assure you more than anything that an 800MHz Astro Saber (and an 800MHz XTS3000) programmed for Smartzone with TX Inhibit turned on WILL RX without issue. This is with Omnilink disabled. I've never tried with it enabled.

I wish there was some way I could show you that it works. It also works just fine on an Astro Spectra with new firmware (not sure what version, but fairly recent).
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Post by motorola_otaku » Thu Aug 16, 2007 1:22 am

Or you could just quit dicking with Smartzone altogether, and use AMSS with a 38-channel CC list. To do this, you set coverage type to Smartzone, then go into the control channel screen and add as many as it'll let you. When done, go back and set the coverage type to AMSS and the full list will still be there. You can edit the frequencies as needed, and the radio will scan through all of them. Obviously you're not going to be able to program alphanumeric site IDs for all 38 entries, but ehn, you can't have everything.

Oh, and this trick only works in RSS. CPS is smart and greys the extra channels out when you switch coverage type.

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Post by mr.syntrx » Thu Aug 16, 2007 2:54 am

r0f wrote:Mike:

The 800 XTS 3000/ASTRO Saber tx inhibit trick doesn't work if your coverage type is set for smartzone. The radio will not unmute to audio. I have no idea how this supposedly works for some people--and not for others. Perhaps it's firmware specific?

I know for a fact radios with 7.71 (and all the way down to 7.08) will not unmute if they can't affiliate, with smartzone enabled.
Same for R07.05.00 on my UHF XTS3000, but I suspect this effect extends to earlier firmware than that as well. I just get 'OUT OF RANGE'.
r0f wrote:Maybe you guys with VHF/UHF trunks experience different results, but there's no way to use smartzone on 800 with tx inhibit enabled. It just won't unmute and keeps searching for sites. Unknown if this has anything to do with Omnilink being enabled.
I get the same result with and without OmniLink on my radios. I've tried setting the receive frequencies as per normal, and the transmit frequencies to 477.400 (Australian UHF CB channel 40.)

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Post by exkalibur » Thu Aug 16, 2007 3:14 am

Well I'd sure as hell love to know why my radios (and those of some friends) don't have a single issue doing RX on SmartZone without affiliating.

The nice thing about SmartZone over AMSS is first of all, Site Lock works properly on SmartZone, but not so great on AMSS. Also, AMSS doesn't give you an RSSI reading. Lastly, with SmartZone enabled, I don't have to mess around with changing sites every so often - SmartZone takes care of that for me. This is especially nice when I'm driving in areas where I don't really know what tower would be the best to use. The radio decides that for me. Sure the talkgroup might not be active on that particular tower, but that's a gamble I guess.
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Post by exkalibur » Thu Aug 16, 2007 3:17 am

To add to this. One other advantage of Smartzone over AMSS. When you loose the control channel on AMSS, it will just continue to search in order of control channel according to what you have programming in. This doesn't always result in the best site. However, with Smartzone, you get to take advantage of neighbour lists. This is really useful if you don't know the area very well - the site tells you which sites are adjacent. AMSS doesn't do that.

I've been using this half-assed SmartZone on my VHF radio for years (as have others) and I've never missed a thing.
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Post by exkalibur » Thu Aug 16, 2007 9:36 am

Yeah, I know what you're saying.

Well I'm glad someone else has told you the same thing I am...at least I know I'm not loosing it :D

Yes, for clarification, the radio is programmed with coverage type as SmartZone.

First shot is an XTS3000 800MHz Model III. Second is an Astro Saber VHF Model III.

I don't have the codeplug/CPS here, but I can get my buddy to take screenshots of whatever other part you'd want to see.

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Post by exkalibur » Thu Aug 16, 2007 11:58 am

They're both the same firmware versions:

R07.22.01
N08.03.02

Flash is the "1C5E" in both radios, and they're both 1 meg.
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Post by exkalibur » Thu Aug 16, 2007 9:26 pm

Okay, just to add a couple of things that I probably should have mentioned.

When I use my radio in "SmartZone", I don't use it with the Site Unlock enabled. The main reason that I use SmartZone over AMSS is because the site numbers reported with AMSS are not the actual site numbers being broadcasted. In addition, AMSS does not give you an indication of RSSI. So the way I use it - I turn Site Lock on - this forces the radio to stay on the current site, even if it looses the control channel (giving you an OUT OF RANGE erroe). Then I'll use the Site Search/Display button to manually find a new site that I want to be on. This will display the site number as well as it's RSSI. Using a map of the towers of the particular system, I can get a good idea of what tower a given talkgroup would be most likely to be found on. From my observations, when you have Site Lock enabled, once you find the site you're looking for, the radio treats it just as if it were a SmartNet site.

That's really the only reason I use SmartZone. I'm not using it for the radio to automatically search and find the best site - I'll only do that if I'm not familiar with the area. Rather, I use it because when it does a site search upon pushing the button, it searches through the current site's neighbour list which makes it a heck of a lot faster/easier to find the site that I want to be on. That, and I don't have to carry around a cross-reference list of what AMSS "Site" is what site number in reality. Now if only you could enable site alias on SmartZone as you can on AMSS, we'd be all set.
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Post by exkalibur » Thu Aug 16, 2007 9:45 pm

Yeah, the OPP/Fleetnet system here in Ontario is somewhat setup like that. Currently there are 3 separate systems on the air. Zone 2 is set up like a SZOL system in that, if you have SZOL enabled on your radio, you can see site aliases.
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Post by grinthock » Thu Aug 16, 2007 9:47 pm

I think we discussed this before, i've had the same trick working on both my XTS3K and the Astro Spectra before with the smartzone trick... On VHF it works -- and never transmits.. I had a bird meter connected to both radios (I think it was a 5W slug) once to prove neither were transmitting. Full receive did open up as long as TX inhibit was on..
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Post by exkalibur » Thu Aug 16, 2007 10:41 pm

r0f wrote: Wishful thinking :)
Not going to happen. The zones aren't interlinked and there aren't any common talkgroups between the zones. Kenora won't be online for probably quite some time.
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Post by VE9MP » Sat Aug 18, 2007 10:24 pm

Okay, heres another scenario...

Say I have an XTS2500 flashed for 3600 baud trunking, any provisions there for scanning without affiliating? or will the radio still want to successfully affiliate before it unmutes like with 9600 baud systems?
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Post by VE9MP » Sat Aug 18, 2007 11:16 pm

Say I have a legit RID and my own talkgroup for my business on a 3600 baud SZOL system, I affiliatewith my RID, lock onto a site, on my talkgroup, then enable scan which includes talkgroups I don't necessarily want to affiliate on, will talkgroup audio come through then?
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Post by VE9MP » Sat Aug 18, 2007 11:32 pm

Thanks Shaun, exactly what I wanted to hear...its a pain in the ass to do it this way, but its better then not at all...I think I know how I can stucture it so its not too horrible...thanks for the info!!
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Post by Credicon » Sat Aug 18, 2007 11:41 pm

r0f wrote:I won't give you the BB "Use a scanner" advice, but yah...it gets a little jewish (hi Seth) when you can't even manually park on a talkgroup any longer with your Moto radio.
I've used a Moto radio since day one, and I have to say with how its looking with the ASTRO25 series of radios, I might just have to break down and buy a scanner, I just wish there was something a bit more durable when it came to portable scanners.

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Post by VE9MP » Sat Aug 18, 2007 11:44 pm

Honestly, I think if it came down to it, I'd give up and not listen at all as opposed to trying to use a scanner, the ruggedness isn't the main thing for me, its the absolute SHITTY audio I detest...
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Post by Credicon » Sat Aug 18, 2007 11:46 pm

VE9MP wrote:Honestly, I think if it came down to it, I'd give up and not listen at all as opposed to trying to use a scanner, the ruggedness isn't the main thing for me, its the absolute SHITTY audio I detest...
Thats one of the big reasons for using a real radio to listen to the local systems for me, but when you have VHF & 800MHz systems in the same area, and you want to listen to both... I guess it comes down to weather you want to have good audio, and ease of use, or the ability to listen across bands/systems with one radio...

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Post by 10-95 » Sun Aug 19, 2007 12:10 am

Credicon wrote:
r0f wrote:I won't give you the BB "Use a scanner" advice, but yah...it gets a little jewish (hi Seth) when you can't even manually park on a talkgroup any longer with your Moto radio.
I've used a Moto radio since day one, and I have to say with how its looking with the ASTRO25 series of radios, I might just have to break down and buy a scanner, I just wish there was something a bit more durable when it came to portable scanners.
I'd recommend the Uniden BCD396T . In my opinion it's the best
thing out there for P25 scanning, that's if you have to use a scanner.

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Post by KB9SXK » Sun Aug 19, 2007 12:59 am

r0f wrote:Yep, that'll work just fine.

I highly suggest you program up an entire zone (16 chans) all the same with your talkgroup, and stick the "scan" members from 17-xx so you can't manually access them. You may still add them to the scan-list in CPS no problem.

The same problem presented itself to me when I flashed an XTS 3000 with host 6 (ASTRO25 exclusive) firmware. Couldn't scan police/fire/ems any longer. The scan-list is restricted to members from ONE trunking personality. So I had to program a legit RID/TG, and put the police/fire/ems above 17, in the same personality.

A real PITA, considering you can only scan 15+1, but it works.

I won't give you the BB "Use a scanner" advice, but yah...it gets a little jewish (hi Seth) when you can't even manually park on a talkgroup any longer with your Moto radio.
Or not...

on Indiana's Smartzone-Omnikink system,
If a radio is not afiliated to a tg, and there is traffic on that on another sit, the site you are picking up will not know to make that tg active. So, you will not hear it. unless another radio is affiated to the active tg in the same site you are on.
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Post by mr.syntrx » Sun Aug 19, 2007 6:05 am

On our SmartZone OmniLink system I never find that to be a problem, because I generally only care about local traffic, and that's what the sites around me always carry.

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Post by MattSR » Sun Aug 19, 2007 7:43 am

Exactly - and whats the other option anyway? Use a scanner? Thats not going to help either...

The only solution to that one is to affiliate - and no one here is that silly.

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Post by KB9SXK » Sun Aug 19, 2007 9:48 am

It yanks me because I want to hear state stuff, but unless it is one one of the few tg that are "pushed" im sol.
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