[App_rpt-users] MASTR III

Fri May 8 23:56:06 UTC 2015

Our MASTR II on Allstar had audio issues... powersupply and bad connections seemed to make it quite acceptable. 

Bob
kk6ecm

-----Original Message-----
From: app_rpt-users-bounces at ohnosec.org [mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of David McGough
Sent: Friday, May 08, 2015 4:49 PM
To: Tim Sawyer
Cc: app_rpt mailing list
Subject: Re: [App_rpt-users] MASTR III

Hi,

I 2nd Tim's comments that GE hardware generally has very good audio. I've 
used Mastr II's, III's and Rangr's with no complaints.

>From what your describing, I suspect you've got flat audio IN/OUT from the
repeater. As Tim mentioned, check the pre-emphasis and de-emphasis
setting.... And, look out for possible ground loops in the audio chain if 
you've got buzzes or low-level distortion.

73, David KB4FXC

On Fri, 8 May 2015, Tim Sawyer wrote:

> It's been a long time ago but I had a MSTR II base connected to IRLP 
which really sounded good. GE generally has good audio so it should work 
well if nothing is wrong with the radio. 
> 
> Of course you have to match the filtering to your radio. If using 
discriminator audio then deemphasis must be enabled. This could likely be 
your missing low end on RX. Sometimes you can tell if the RX filtering is 
correct just by making sure all the touch tones decode properly. Bring up 
the *CLI> with verbose 3 and play each tone to see if itâ€™s decoded. Be 
sure you have good CTCSS filtering (in your radio or voter.conf or even 
both) because that will cause TT decode problems without. 
> 
> For TX feeding to a non-mic type input will require preemphasis.  If 
you are using a mic input, which I recommend, make sure there is not a DC 
bias on the mic. An easy way to tell if the TX filter is right is to 
connect to a known correctly setup node and listen to the squelch tail 
and user audio. The squelch tail will be obviously high frequency 
sounding if doubled preemphasized or muddy if emphasis is needed. 
> 
> Okay, so much for general audio filtering information. Now on to RTCM 
specifics.
> 
> The filter settings in the RTCM are a bit obscure. It tries to 
automatically do the right thing but it isnâ€™t always what you want. The 
RX filter is controlled by the COR Type (menu 13). 13 = 0 assumes 
discriminator and thus deemphasizes. 13 = 1 assumes non-discriminator and 
thus has no deempahis. There is also a nodeemp setting in voter.conf 
which may be needed in unusual situations. 
> 
> The  hidden filter trick on TX is setting a CTCSS tone. If you set a TX 
tone the RTCM assumes a CTCSS input and thus will preemphasize. With no 
CTCSS tone  there will be no preempashis. Generally I think the radio 
should do the preempashis (and tone encoding) as the manufacture knows 
best what their radio should do. But for simulcast or if you just want 
AllStar to sent the CTCSS tone then you must feed the radio at a point 
where it will not emphasis. You can fake it out if you want emphasis 
without a CTCSS tone by setting the txctcsslevel=1 (or other very low 
level) in voter.conf.  
> 
> Hope that helps.
> --
> Tim
> :wq
> 
> > On May 8, 2015, at 10:44 AM, Jeff Carrier <k0jsc.jeff at gmail.com> wrote:
> > 
> > Both TX and RX more or less.  The RX path lacks a lot of the low end 
but is clean.  I'm having more trouble with the TX path.  I tried DPLX 
Line A/B as indicated in the how to but the transmitted audio lacks 
fidelity and is missing the low end (both from local and network audio).  
It's also slightly raspy and seems to distort if the remote user has a 
hotter mic and the deviation exceeds 3 kHz.  I know the RTCM can sound 
really nice I've got a few paired with motorolas.  I had this same issue 
with the MASTR II and I would up giving up on that.
> > 
> > On Fri, May 8, 2015 at 10:14 AM, Tim Sawyer <tim.sawyer at mac.com <mailto:tim.sawyer at mac.com>> wrote:
> > Please elaborate on â€˜really nastyâ€™. Is it the RX side or the TX side?
> > --
> > Tim
> > :wq
> > 
> >> On May 7, 2015, at 8:42 PM, Jeff Carrier <k0jsc.jeff at gmail.com <mailto:k0jsc.jeff at gmail.com>> wrote:
> >> 
> >> I don't want this to sound like a dumb question and I've searched all over with really no luck.  I've also tried several things but I'm looking for "clean" audio.  I've done this a million times on Motorolas so why doesn't this work on a GE?  Does anyone have experience with an RTCM and a MASTR III?  I have tried to inject audio into every point I can find in the manual and can't make it sound "right."  There is a good write up on repeater builder about interfacing a controller with an M III but when I follow that it sound REAL NASTY.  Any tips would be greatly appreciated.
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