Nac decoding ?

[SCPD]

I assume you will need a scanner with a discriminator tap correct?

Yes.

must it be a P-25 scanner like a Pro-96 or will any tapped (analog) scanner do?

Any will do.

What about a data slicer?

Nope.

What computer port is the program looking for the data on, i.e., serial port, line in, microphone, e.t.c.

Default sound input (you can set this in Windows).

Will the program run on Windows 98, XP?

2K and XP yes. 98 - maybe.

-rick

 

[mam1081]

Thanks Rick!!!

I cannot wait to get home and try it out. First, a couple of questions; I assume you will need a scanner with a discriminator tap correct? If yes, must it be a P-25 scanner like a Pro-96 or will any tapped (analog) scanner do? What about a data slicer? What computer port is the program looking for the data on, i.e., serial port, line in, microphone, e.t.c. Will the program run on Windows 98, XP?

Thanks again
Wayne

I second that. I'm going to run it as soon as I get home. There should be lots of new NAC codes in the rrdb soon!

 

[mam1081]

Troubles.

I can't get it to work!

I get the program to run, set to default sound input, and after about 2 seconds, the white background around the "000" turns grey. I tried in invert and not inverted. I can run Unitrunker with the same set-up, so I assume all that is working (computer sound input and scanner tap point).

Any pointers or ideas?

Thanks!

 

[SCPD]

I tried in invert and not inverted. I can run Unitunker with the same set-up, so I assume all that is working (computer sound input and scanner tap point).

The basic settings for the NAC decoder should match your Unitrunker settings - particularly in regards to signal invert. If Unitrunker works for EDACS and Motorola ... that's a good sign. Is Unitrunker actually using the "Default" sound input or something more specific? [ A future version will allow choosing something else for input - I was in a hurry. ] Also - you may need to adjust the signal level - probably need to reduce volume slightly. Run a software oscilloscope display so you can see the actual live signal while making your adjustments.
-rick

 

[Wayne]

NAC decoder

I tried the program on two different PC's running Windows 98, I get a "failed to start" error. No problem though as it runs fine on XP after tweaking the line in audio settings. My experience so far with it has been good decoding on clean local signals. Skip transmissions like DPS P25 are not decoding as well since I think the signal is mixed with analog and other noise.

If there is a future enhancement, adding a logging feature would be useful as well as some of the earlier suggestions like TGID and the like.

Thanks again Rick for another great decoding program!!!

Wayne

 

[DaveNF2G]

I have it running under XP. So far, National Grid has been dead quiet today (that always happens when I get new equipment anyway). I caught a couple of P25 transmissions and kNACk showed "FFF" on the display.

I just reviewed the thread and I see I should be using a tapped scanner. I have been running it on earphone audio from a BC296D. I'll see what it does on my tapped BC-235.

 

[grem467]

Am i correct in assuming this will need discriminator out, and that any RX with such will work?

ie not needing an astro capable RX?

 

[swest90]

I tested this last night with a 895xlt tapped. Used the saber and wammo, comes up right away. Works awesome!

Once again great job.... Very impressive.

 

[mancow]

What's your pc / receiver setup? Maybe we can duplicate some of it to get our stuff working.

 

[SCPD]

Am i correct in assuming this will need discriminator out, and that any RX with such will work?

Correct - audio taken from a narrow FM discriminator tap.

-rick

 

[grem467]

sweet.. now of course all the astros i want to get the nac for are quiet.. lol

 

[FLANO]

Rick,

Very nice...I've got about 30 known P-25 frequencies here and I've begun recording their NAC's. Now if we could only get the scanner makers to add that as an option when decoding P-25 signals, so that we can block out the unwanted intermod garbage

John
SE of Tucson

 

[mancow]

Cool stuff. The NAC decoder seems to work fine for me.

I'm still having trouble with the unitrunker program on P25 systems. Rick, you mentioned using an oscilloscope program to look at the control channel. I found one and took a screenshot of what the laptop is seeing from the modded PRO-83. This is the same setup that the NAC decoder was used with and it worked fine.

The image is of the scope running while reading the tapped PRO-83 while it is listening to one of the control P25 control channels.

 

[mancow]

I forgot to say THANKS for making the NAC program.

I found the MDC decoder for Windows this week too. Two programs I never thought I would see. Who could ask for more?

 

[SCPD]

I forgot to say THANKS for making the NAC program.

You're very welcome. I'll post a slightly improved version that allows you to choose the sound input (so you don't have to change the windows default) and will also run on Windows 98 (probably '95 too).

The image is of the scope running while reading the tapped PRO-83 while it is listening to one of the control P25 control channels.

Yep. I see a slightly fuzzy C4FM signal. An ideal signal will be smooth. I'll post an example. Some of the distortion may be caused by an impedance mismatch between the radio and computer. Is this signal coming straight from the PRO-83 or is there a small buffer amp?

The simpler two-level signals can tolerate this but - I'm sorry to say - that's not so for C4FM and CQPSK.

-rick

 

[blantonl]

Where is the MDC Decoder?

 

[jimvv]

I have tried and tried to get Unitrunker and KnacK to work with no luck... I am sure I need a buffer amplifer. Can someone post a link to some easy schematics. I have tried to look on the net and not sure exactly what I need... Thanx in advance.
Jim

 

[Joseph11]

Lindsay: http://www.antistatic.org/winmdcd/

 

[mancow]

You're very welcome. I'll post a slightly improved version that allows you to choose the sound input (so you don't have to change the windows default) and will also run on Windows 98 (probably '95 too).

Yep. I see a slightly fuzzy C4FM signal. An ideal signal will be smooth. I'll post an example. Some of the distortion may be caused by an impedance mismatch between the radio and computer. Is this signal coming straight from the PRO-83 or is there a small buffer amp?

The simpler two-level signals can tolerate this but - I'm sorry to say - that's not so for C4FM and CQPSK.

-rick

The signal is coming straight from the 83's discriminator.
Do you have ay suggestions what to use for a small amp? Is there a schematic somewhere? A local RadioShack went under so I grabbed about $150 in parts that were dirt cheap. Surely I can make one with all of that.

 

[SCPD]

Can someone post a link to some easy schematics. I have tried to look on the net and not sure exactly what I need... Thanx in advance.
Jim

Some options:

1. Most places that sell electronic kits will have a hi-Z microphone preamp.
2. using the datasheet for a common a JFET op-amp - build a voltage follower.
3. guitar pre-amp - I've seen circuits on the 'net using a single UJT or JFET transistor - should work.

We have a Wiki page for data slicers - we need one for buffer amps.

-rick