Cell info

[Big Benny]

What if I have something on a PCS1900 frequency

Frequency 1945.2M Configuration 1 CCCH not combined

Neighbour Cells 587 

ARFCN 33355

Will grgsm_decode be able to decipher that type of setup ? I'm going to try it with BCCH even though supposedly on Google it seemed to say it won't work from what I understand and I'm on 2g using gmon pro because

The arfcn given with gmon pro is invalid when running a capture 

[Al]

For that frequency your ARFCN should be 587

The ARFCN 33355 isn't a valid channel for any cellular technology on any band. 

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[Big Benny]

Okay uh but I'm looking at grgsm_capture 

So would it be 

grgsm_capture 2G.cfile -a 587 --args=hackrf -T 60 

Frequency is 1945.2M

On Sun, Jul 31, 2022, 8:44 AM Al <al.hig...@gmail.com> wrote:

I'm not overly familiar with capturing traffic, I would imagine that's correct - looks like enough arguments anyhow. 

There doesn't appear to be any gain (-g) added, in the UK when looking at grgsm_scanner or livemon I normally add a gain value of at least 30 (-g 30). 

On Sun, 31 Jul 2022, 14:38 Big Benny, <burnerm...@gmail.com> wrote:

So I run grgsm_capture cfile -a 587 --args=hackrf -T 60

[Big Benny]

My ARFCN band is invalid when running gr-gsm capture 

[Al]

That RFC number doesn't look right to me. I can't explain what's going on there, the number is a LTE EARFCN not GSM ARFCN but the presence of a BSIC confirms GSM. Never seen that before. 

[Big Benny]

Any ideas bro 

[Al]

On gmon can you see a LAC and CellID decoded? I won't ask what they are.

[Big Benny]

Yes and when running livemon capture the immediate assignment shows 

SDCCH8 time slot of 1 on frequency 1945.2M 

PCS1900

[Al]

Can you also see the System Information messages?

[Big Benny]

Yes I can see the system information message I'm looking at it right now

BCCH 1

 ARFCN 587 

Time slot 0payload type gsm Um 

Downlink

All of this from a pcapng file and livemon

Apart from immediate assignment info

On Sun, Jul 31, 2022, 11:23 AM Big Benny <burnerm...@gmail.com> wrote:

Yes I can see the system information message I'm looking at it right now

BCCH 1

 ARFCN 587 

Time slot 0payload type gsm Um 

Downlink

All of this from a pcapng file and livemon

[Big Benny]

This is what I'm looking at on livemon 

[Nikos Balkanas]

ARFCN 587 is valid gsm arfcn in PCS1900 and DCS1800...
There is overlap with LTE band 1..

Nikos

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[Al]

The only thing I can think of with regard to capture is to use the frequency (-f 1945.2M) rather than ARFCN flag (-a). The fact the ARFCN is repeated on PCS and DCS bands could be causing the issue. 

I'll be 100% honest, I don't know if -f is even a thing for grgsm_capture, it is for livemon. 

[Nikos Balkanas]

-f & -s are standard with all grgsm tools. If in doubt use -h...
Frequencies overlap even more than arfcns...
That's why you have to see first the signal in livemon to see if it
looks like GSM or LTE...
decode has a switch to tell if the traffic is DCS1800 or PCS1900 if
the arfcns overlap;-)

Nikos

[Chill Vibes]

Hey I reset my phone so this is where I'm at now

It's the same info for what I'm pulling I was wondering if anyone would he able to help like Al or Nik thanks y'all I'm off to work