New to scanning

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jcostab

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Hi all,

I'm brand new to scanning and looking for a little guidance. I'm located on the Mornington Peninsula, near Melbourne Australia. Long term I'd like to be able to listen in on the CFA (country fire authority) channels near me, as I'm a volunteer. They operate on Phase 2 P25, unencrypted, from what I've been able to tell.

I've just purchased an RTL-SDR v3, with a dual telescopic indoor antenna, and have installed op25 and GQRX on Ubuntu, and have been able to successfully listen to commercial FM broadcast channels on GQRX

Now I'm trying to get something happening in op25, but so far have had little success. Unfortunately none of the tutorials I've found are local to me, so it's difficult to follow along. When I try any of the command lines to start OP25, it starts, but I have all zeros in the top line, and it doesn't look like it's receiving anything.

The frequencies are here - Victoria - Country Fire Authority Scanner Frequencies and Radio Frequency Reference and here - RMR Network Sites, with Arthurs Seat being the closest tower to me, but no matter where I enter those frequencies, in op25 or GQRX, I don't seem to see any traffic.

Is anyone familiar with scanning CFA near Melbourne?

Thanks in advance... I realise I'm a bit vague, but still trying to get my head around all this!

Cheers
 

K4EET

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Hi jcostab and welcome to Radio Reference! From the information that you provided I was able to find the Talk Group IDs (TGID) for the Fire Department on CFA's trunking system. They are shown here:


The CFA Digital Fireground Channels are found here:


Now I am not at all familiar with the RTL-SDR v3 receiver or any of those RTL-SDR type receivers. But if I were programming a Uniden BCD536HP Scanner (U.S. version), I don't think, between the webpages that you cited and the webpages that I have cited, that there is enough information yet to enable us to monitor what you are looking for. I could be wrong because I am also not at all familiar with how the RMR Network is actually configured. I'll keep probing around the Vicradio Zone website. Until I find some more information...

Cheers!

Dave
 

N8IAA

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Hi all,

I'm brand new to scanning and looking for a little guidance. I'm located on the Mornington Peninsula, near Melbourne Australia. Long term I'd like to be able to listen in on the CFA (country fire authority) channels near me, as I'm a volunteer. They operate on Phase 2 P25, unencrypted, from what I've been able to tell.

I've just purchased an RTL-SDR v3, with a dual telescopic indoor antenna, and have installed op25 and GQRX on Ubuntu, and have been able to successfully listen to commercial FM broadcast channels on GQRX

Now I'm trying to get something happening in op25, but so far have had little success. Unfortunately none of the tutorials I've found are local to me, so it's difficult to follow along. When I try any of the command lines to start OP25, it starts, but I have all zeros in the top line, and it doesn't look like it's receiving anything.

The frequencies are here - Victoria - Country Fire Authority Scanner Frequencies and Radio Frequency Reference and here - RMR Network Sites, with Arthurs Seat being the closest tower to me, but no matter where I enter those frequencies, in op25 or GQRX, I don't seem to see any traffic.

Is anyone familiar with scanning CFA near Melbourne?

Thanks in advance... I realise I'm a bit vague, but still trying to get my head around all this!

Cheers
You do know that there is a forum just for Australia further down the forums pages?
If you click on report, and ask, the moderators will be glad to move your question to the right place. It will make it easier to get a response from those who live near you. :)
 

jcostab

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Sep 23, 2019
Messages
11
Hi jcostab and welcome to Radio Reference! From the information that you provided I was able to find the Talk Group IDs (TGID) for the Fire Department on CFA's trunking system. They are shown here:


The CFA Digital Fireground Channels are found here:


Now I am not at all familiar with the RTL-SDR v3 receiver or any of those RTL-SDR type receivers. But if I were programming a Uniden BCD536HP Scanner (U.S. version), I don't think, between the webpages that you cited and the webpages that I have cited, that there is enough information yet to enable us to monitor what you are looking for. I could be wrong because I am also not at all familiar with how the RMR Network is actually configured. I'll keep probing around the Vicradio Zone website. Until I find some more information...

Cheers!

Dave
Thanks so much for taking the time to respond Dave. I expected that properly setting up to receive the CFA channels would be difficult, but I'll keep persevering.

In the meantime, I'm hoping to at least find a few interesting things to listen to, other than commercial FM broadcast radio, so that I get a hang of how everything works.

Thanks again.
 

jcostab

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Messages
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You do know that there is a forum just for Australia further down the forums pages?
If you click on report, and ask, the moderators will be glad to move your question to the right place. It will make it easier to get a response from those who live near you. :)
Thanks... I had seen that, and did wonder which forum to post in. Being my first post, and such a beginner type question, I thought this was the best fit, but happy for it to be moved if the moderators think it's better in the Australia forum.

Cheers,
John
 

K4EET

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Messages
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Location
Severn, Maryland, USA
<snip> happy for it to be moved if the moderators think it's better in the Australia forum. </snip>
jcostab, if you would like for this thread to be moved to the other forum, simply press the "Report" link in the bottom left of any post and ask the moderator to move your thread. They prefer that you do this rather than creating another thread in the other forum.

Cheers! Dave
 

jcostab

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Messages
11
what command lines are you trying in op25?
Hi a417,

My op25.sh script contains the following:

./rx.py --nocrypt --args "rtl" --gains 'lna:36' -S 960000 -q 0 -d 0 -v 1 -2 -V -U -T trunk.tsv 2> stderr.2

my trunk.tsv file contains the following:
Sysname​
Control Channel List​
Offset​
NAC​
Modulation​
TGID Tags File​
Whitelist​
Blacklist​
Center Frequency​
IC22C 803​
162.8125​
0​
0x63E​
cqpsk​
IMC 259​
165.125​
0​
0x4A4​
cqpsk​
D08AV​
163.7875​
0​
0x4A4​
cqpsk​
D08C 280​
161.075​
0​
0x4F9​
cqpsk​
D08E 282​
161.1375​
0​
0x4F9​
cqpsk​
Arthurs Seat​
166.675​
0​
0x163​
cqpsk​
Arthurs Seat Alt​
166.525​
0​
0x163​
cqpsk​

The op25 window looks like this when it's running:


79574

I'm not really sure whether my command line is wrong, I've entered the wrong frequencies, or there's just never anything happening on those frequencies when I've tried, but I've not heard any audio at all when running op25.

Thanks,
John
 

a417

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Mar 14, 2004
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2,104
the fact that 'tsbks' = 0 means that it is not finding any data to decode.

Lets walk before we can run.

Drop the all the arguments you are passing to it, except the following 4

Code:
./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f [your frequency here]
if you can actually decode the datastream, the tsbks should start counting up like crazy

so, to verify I can hear my local p25 system...I do this
Code:
./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f [853.7875e6]
If you use something "simple" (hah) like GQRX, can you confirm you can actually find the datastreams on those frequencies, AND that your dongle is not drifting?
 
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jcostab

Member
Joined
Sep 23, 2019
Messages
11
the fact that 'tsbks' = 0 means that it is not finding any data to decode.

Lets walk before we can run.

Drop the all the arguments you are passing to it, except the following 4

Code:
./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f [your frequency here]
if you can actually decode the datastream, the tsbks should start counting up like crazy

so, to verify I can hear my local p25 system...I do this
Code:
./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f [853.7875e6]
If you use something "simple" (hah) like GQRX, can you confirm you can actually find the datastreams on those frequencies, AND that your dongle is not drifting?
Thanks so much for your help a417!

So, I've tried the following command line, as you suggested, and I can now see that is seems to be doing something, and the tsbks are indeed counting up... definitely a big improvement already!! :D

./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f 166.6750e6


79577



As for using GQRX to confirm, I'm not really sure what settings to use, or what to expect when I listen to the control frequencies?

There does appear to be something going on on that frequency, and my dongle doesn't appear to drift when listening to broadcast radio.

Here is a screengrab of GQRX:

79578
 

a417

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Messages
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Ok, so you can recieve stuff. Lets keep going.

Now we're going to tell it to (-t) autostart scanning talkgroups, (-U) and enable internal audio player, and (2> stderr.log) redirect the error messages to the file named 'stderr.log' for later perusal. That's a 'greater than' symbol, not a chevron.

Code:
./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f 166.6750e6 -t -U 2> stderr.log
you can ditch GQRX now, that's just a 'simple' way to make sure that you can recieve stuff and visualize it.
 
Last edited:

jcostab

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Sep 23, 2019
Messages
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Ok, so you can recieve stuff. Lets keep going.

Now we're going to tell it to (-t) autostart scanning talkgroups, (-U) and enable internal audio player, and (2> stderr.log) redirect the error messages to the file named 'stderr.log' for later perusal. That's a 'greater than' symbol, not a chevron.

Code:
./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f 166.6750e6 -t -U 2> stderr.log
you can ditch GQRX now, that's just a 'simple' way to make sure that you can recieve stuff and visualize it.
This is so amazingly helpful of you!

Okay, so using your new command, for the CC channel of Arthurs Seat - 166.6750 - it appears to lock on and the tsbks counts up, but nothing else seems to happen. It's possible that this is because there is not much happening on the radio around here at the moment, I guess?

./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f 166.6750e6 -t -U 2> stderr.log

79587

If I change to another nearby tower's control channel frequency - Cowes on 166.5875 - I get much more going on, so perhaps this is a better frequency to experiment with.


./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f 166.5875e6 -t -U 2> stderr.log

79588

I'm still not hearing anything though.

Thanks again!

John
 

a417

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Joined
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Messages
2,104
Ok, getting there.

Now, we know you can recieve a system - and decode it to the point where you are getting talkgroups. What we will do now is single in on the "Cowes" system, and make a 'cowes-trunk.tsv' specifically for it, this way we can get you with something that works, and then we will go from there.

You will want to open "trunk.tsv", and immediately save-as 'cowes-trunk.tsv'. (or you can make a new file, or copy the old one to a new name...your choice) ** TSV stands for TAB SEPARATED VALUES...so...IF YOU OPEN IT IN A TEXT EDITOR LIKE PICO/NANO/VIM/EMACS, etc... You will have to remember that this is a TAB DELIMITED file, and there are TABs between the columns, and spaces will not work. If you open it in a graphical spreadsheet, you do not have to worry abut the same.

You will then open the cowes-trunk.tsv and make valid entries in the FIRST FIVE columns, and they need to be surrounded by the double quotes.
Code:
"Sysname"    "Control Channel List"    "Offset"    "NAC"    "Modulation" (etc..not listing the rest for brevity)
"cowes"    "166.5875"    "0"    "0x8a1"    "CQPSK" (double quotes empty for remainder of this line)
save the file as cowes-trunk.tsv in the op25 folder, and get ready for a new command line.
Code:
./rx.py --args 'rtl' --gains 'LNA:49' -S 960000 -f 166.5875e6 -T cowes-trunk.tsv -U 2> stderr.log
Remember, the 'greater than' symbol in your command line redirects error messages to a file called 'stderr.log', so you look there if something is weird or wrong.
 

jcostab

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Messages
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Wow... we're definitely getting closer!

So I've done as recommended, and created cowes-trunk.tsv, but needed to change the NAC to 0x16b, as 0x8a1 was resulting in no tsbks.

I'm also getting various "voice frequency tgid's" at the top of the screen, and some "talk group ID, TDMA slot" messages at the bottom, and more importantly, I have actually heard some live voice messages! I can't tell you enough how excited I was when I heard a live message! :D


79602

I know that there is a way to enter the various talkgroups into a separate tsv file, but I'm not sure why I need to, or would want to do that? Am I only hearing some messages that are coming through this control channel?

I also don't really understand how all the various towers and control channels fit together... am I likely to need to add multiple tower control channels to my cowes-trunk.tsv file, or will one tower give me access to all the talk groups that the CFA use?

Sorry for all the dumb questions! You've definitely help me get from nowhere to listening to live voice traffic, so I couldn't be happier.

Cheers,
John
 

a417

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Messages
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Wow... we're definitely getting closer!

So I've done as recommended, and created cowes-trunk.tsv, but needed to change the NAC to 0x16b, as 0x8a1 was resulting in no tsbks.

I'm also getting various "voice frequency tgid's" at the top of the screen, and some "talk group ID, TDMA slot" messages at the bottom, and more importantly, I have actually heard some live voice messages! I can't tell you enough how excited I was when I heard a live message! :D
It's a good feeling, isn't it?

I know that there is a way to enter the various talkgroups into a separate tsv file, but I'm not sure why I need to, or would want to do that? Am I only hearing some messages that are coming through this control channel?
Right now, it's decoding all it can decode, without giving you definitive names for the talkgroups. If you can map the TGIDs to logical names, they will show up at the bottom of the screen.

I also don't really understand how all the various towers and control channels fit together... am I likely to need to add multiple tower control channels to my cowes-trunk.tsv file, or will one tower give me access to all the talk groups that the CFA use?
You will usually only need one tower, the one you get the best signal from. If you were mobile, you might need more. Each tower will (usually) have several frequencies that it transmits on, and you should have the primary control channel for that tower (and the secondaries) listed in the trunk.tsv file are you using. The tower has secondary channels in case the primary unit has issues or needs to be switched off, so the services don't get interrupted.

Think of it this way.

Your subscriber unit is closer to tower X, it will find the control channel on Frequency A on that tower and listen to instructions on Frequency A. if you move too far from tower X, and closer to Tower Y... Tower Y will have to be on a different frequency...or the channels will interfere...So Tower Y might be on Frequency B for instructions. Etc...

Now that you're getting something, you can control what you want to hear. Whitelisting allows only those TGIDs you want, Blacklisting bans the listed TGIDs, very simple to control the flow of what you want to listen to.
 

a417

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I had the mods move this to your locale, as anything else you might need will probably be best confirmed by someone who's not on the literal other side of the world.

Cheers, mate. (y)
 

jcostab

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I had the mods move this to your locale, as anything else you might need will probably be best confirmed by someone who's not on the literal other side of the world.

Cheers, mate. (y)
Thanks for all your help - i’m so pleased with how it’s working now. I obviously have a lot to learn, but I can hear what I’m interested in for now and will play around with other frequencies and towers to see what else I can find.

Cheers,
John
 

K4EET

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Location
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jcostab (John), I followed along with interest from the beginning with great interest. I might have to invest in one of those RTL-SDR v3 dongles one day. I would like to learn how to learn to use them as well. Thanks to you and a417, my interest has been kicked up a notch from where I was. This was quite an interesting thread, even if I don't quite understand all that is going on. But thanks for allowing me to tag along with you guys from the beginning.

Cheers mate! Dave
 
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