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Clarifying whether MERA is digital-only or not

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WayneH

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#1
I've been seeing a few people submit to the database that MERA is an all digital trunked system. This is untrue. It may seem like it is as a majority of the traffic is digital but the system is setup for both digital and analog operation. The system announces this as so. The analog talkgroups are the ones low in number (e.g., 16, 48, 80, etc). In order to do data on a talkgroup like that you have to set the talkgroup up for analog operation as it won't work in digital; IMBE digital is designed for human voice.

-Wayne
 

SAR923

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#2
I suppose it's possible for non-digital traffic to be broadcast over the MERA system but I haven't heard any in six months of monitoring. 0016 is a typical talkgroup for radio techs testing sites and they are always in digital so I'm a little baffled by your assertion that the low TG's can only be analog.
 

inigo88

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#3
Can you go into a little more detail as to what the techs are using TG 0016 for? I've been hearing the same data telemetry sounds on it for quite some time and I've been really curious as to what exactly they're doing with it. I think it might be analog because I think the mode indicator in the top right of my Pro-96's display switches from +DG (IMBE digital) to +MO (Conventional motorola trunking), and that would make sense with what Wayne said about IMBE being optimized for the human voice, but I'll try and confirm that first rather than assert something I'm not sure about and make an ass of myself. :D :lol:
Thanks guys,

-Inigo
 

WayneH

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#4
Generally there's some logic to the assignment of talkgroups, and that being they're either at the beginning of the talkgroup numbering scheme or the end. Folks are getting a little more creative but most admin don't have the talent to intermix analog and digital. Take San Francisco's system as an example, though the opposite. Digital talkgroups in the low range, the rest (from 8208 on up) are set for analog.

Looking at the database it says, and just as I thought I once heard it, telemetry/data on TG16. Also, if they're using a talkgroup to send Knox DTMF to their boxes they'll need to set the talkgroup up for analog operation. Anything other than human voice won't work in digital, and yes I'm aware that you can pass DTMF through the background data, but Knox DTMF is different than standard DTMF, hence the need for analog.

Like I said, you may not hear any but there are, or will be, analog talkgroups configured for MERA. Each site announces this in the data over the control channel; I'm not just guessing here. San Mateo, though, is completely digital.

-Wayne
 
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#5
i'll do a test in the next few days or week.
i'll try to load it up on my pro95 and combare it to the pro96
if anybody has it allready set it up on the pro95 i could do it sooner then later
i'll let you know as soon i can
 
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#6
done some tests from home
loaded pro 95 with mera and just a few alpha tags and left it in the open mode. can't recive anything . its all just noice.
on the pro96 hear it all.

had an old San Rafael 33.98 all noice now on both Scanners
" " Marin SO 39.24 yes still hear it on pro95
" " Marin FD 37.1 yes still hear it on the pro95
was able to confirm Marin SO, FD same time on pro96 listen to Mera

So it seems Mera is all Digital ........
 
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#7
We ran Trunker on it today, and saw at least one TG come up that did not show digital. We couldn't hear it (the Pro-96 couldn't decode the channel that Trunker was getting), but Trunker clearly showed an analog TG.
 

WayneH

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sfdf said:
So it seems Mera is all Digital ........
Yeap, since during the time you listened you didn't hear anything analog, so regardless of what happens any other time, the system is completely digital. Riiiiight... :roll:

This is the last time I say it... There ARE analog talkgroups configured for MERA. This does not mean they're used all the time or they're used at all right now, but there are analog talkgroups in their database.

What do you people want in the database? What appears to be right from a scannist's point of view or what is really right.

-Wayne
 
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#9
RolnCode3 said:
We ran Trunker on it today, and saw at least one TG come up that did not show digital. We couldn't hear it (the Pro-96 couldn't decode the channel that Trunker was getting), but Trunker clearly showed an analog TG.
This is true. I was with him. 8)
 

inigo88

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#10
CONFIRMED: Talkgroup 16 is analog, motorola trunked. No surprise there. If anyone wants a sample of it I made some .wav files, it's just data-burst telemetry but I'd be interested if someone could identify what the radio shop (or another user) is using it for. Drop me a PM with your email address if you might be able to help, and I'll send it.

Thanks,

Inigo
 
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