OP25 Some basic questions

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Falcon4

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Just wanted to ask about tsbks...what does this stand for? Is this like a data counter? Also the number in parentheses next to the frequency what does that number indicate? Thank you!
 

boatbod

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Just wanted to ask about tsbks...what does this stand for? Is this like a data counter? Also the number in parentheses next to the frequency what does that number indicate? Thank you!
TSBK = Trunk Signaling Block
MBT = Multi Block Trunking (extended for of a TSBK)

Both are signaling packets providing information between the SU and RFSS. In other words, op25 listens for TSBKS (and MBTs) to learn about calls in progress and other network activity. The counter increments whenever the app is parked on a control channel.

Number in parenthesis at the bottom of the terminal screen is the frequency offset (fine tune).
 
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boatbod

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Hey,@boatbod In reference to LNA what is the optimal Noise Floor to Reception (DB)(Gnuplot 5)? Sneaking a quck question in before the weekend gets kicked off :)
There's really not a "right" answer. You want a low noise floor and a strong signal giving you a low SNR and solid decode.
Increasing the LNA gain usually increases the noise floor at the same time, but it's not a linear relationship, so the usual methodology is to increase LNA until you start seeing the noise floor rise significantly, then back off a bit.
 

Falcon4

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There's really not a "right" answer. You want a low noise floor and a strong signal giving you a low SNR and solid decode.
Increasing the LNA gain usually increases the noise floor at the same time, but it's not a linear relationship, so the usual methodology is to increase LNA until you start seeing the noise floor rise significantly, then back off a bit.
I've been toying with 20-25-40 20 is good when the system isn't busy....bump up to 25 I see the noise floor spiking a bit but still good decodes I'm going to rock out with 20 for a Saturday night because I don't get the crazy mic chirps. Site is 10 miles away getting-40db and -90 on noise floor only worry is im missing out on transmissions but it sounds so clean
 

boatbod

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I've been toying with 20-25-40 20 is good when the system isn't busy....bump up to 25 I see the noise floor spiking a bit but still good decodes I'm going to rock out with 20 for a Saturday night because I don't get the crazy mic chirps. Site is 10 miles away getting-40db and -90 on noise floor only worry is im missing out on transmissions but it sounds so clean
-40db signal with -90db noise floor sounds like a solid decode. How tight are the constellation plot clusters? Ultimately that's the real metric for how good a signal you are pulling in.
 

Falcon4

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87308

Was checking my logs from last night and noticed the above (the preceeding 0's as well as multiple PCM runs) It seemed to work itself out around 2300. What would cause this condition bad decodes? Also, I noticed a couple of messages on increasing logging activity is there anyway to log the radio ids as well.
 

boatbod

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The "O"s are gnuradio overflows - typically when the flowgraph cannot keep up with the incoming sample rate, causing data to get dropped.

Options are:-
- faster cpu
- limit other activity on the machine
- lower the SDR's sample rate

If you are running gnuplots, turn them off as these eat up cpu very quickly.
Set the sample rate to 960000 (or less if you can get it to work reliably). Many people start out with it at -S 2400000 but it's just not necessary for op25.
 
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