[App_rpt-users] AllStar Node / repeater radios

Thu Sep 24 14:28:36 UTC 2015

This should be on the freestar reflector I think (re: “dstarrepeaterd” program – the “sound card” DSTAR modem)

I found that the low-pass filtering in the URI limits the frequency response so that it does not reproduce the baseband signal with enough fidelity to work on DSTAR GMSK.  The result is a lot of errors on the DSTAR side.  As posted many times on the other reflector, the absolute cheapest sound fob with no filtering seems to work best (but make sure your transmitter has at least some filtering).

Having said that, as an experiment, I changed the relevant surface-mount capacitors in one channel, of one of my URIs, and it worked fine on DSTAR.

Regards

Ken

KE2N

From: Skyler F [mailto:electricity440 at gmail.com] 
Sent: Thursday, September 24, 2015 10:17 AM
To: app_rpt-users at ohnosec.org
Subject: Re: [App_rpt-users] AllStar Node / repeater radios

Is it possible to use a URIx for freestar yet or do you still need a hardware board for the digital stuff? I know they were working on something for software.

On Thu, Sep 24, 2015 at 8:15 AM, Steve Zingman <szingman at msgstor.com <mailto:szingman at msgstor.com> > wrote:

Digital needs unfiltered receiver and transmitter audio. I've done it with D-STAR and DMR. I have only setup a SM-50 as a user radio.

Steve

On 9/24/2015 10:05 AM, Skyler F wrote:

Well my personal experience with a baofeng node is really good audio reports, and sometimes better than my motorola SM-50 discriminator audio. I just use the internal tone decoder in those baofeng radios for COR.  

Would they not be suitable for DSTAR though?

On Thu, Sep 24, 2015 at 7:41 AM, Steve Zingman <szingman at msgstor.com <mailto:szingman at msgstor.com> > wrote:

On 9/24/2015 9:30 AM, Skyler Fennell wrote:

Can I have an explanation of why discriminator is needed for anything but actual digital modulation like 9600 baud?

To prevent PL tones?
Nope, when plugging in good headsets I can hear the CTCSS tone from the repeater and even on the baofeng.

Lack of high frequency noise?
Put a high pass filter

Someone please explain why discrim is needed. Good audio is good audio and can't it be manipulated to fit the needs of the application?

Maybe I don't want other filters inline, I want total control of the receive audio. de-emphases CTCSS filtering etc. 

If worried about audio levels, put an AlC which automatically feeds the system (weather Allstar or free star) with the perfect level independent of the level of the user.

Please note I'm only talking analog.

73
Skyler KD0WHB

On Sep 24, 2015, at 7:15 AM, Steve Zingman <szingman at msgstor.com <mailto:szingman at msgstor.com> > wrote:

Being a DSP based radio, the BF888 is a cheap low power analog only RF package. Given the lack of discriminator and modulator access it is limited.

For a receiver the Maxtrac  / Radius / GM300 work well. For a transmitter not so much. Heat output and with the Maxtrac, problems with power and deviation control out of band can cause problems without custom firmware or hardware hacks.

My absolute favorite RF gear for Analog / Digital repeaters is Tait. The T800 series is a purpose built programmable Exciter / Receiver package. With access to all the signals anyone would want. I started using them for 927 MHz repeaters and have had great performance on UHF and VHF. Mix and match at will. Pair a VHF receiver with a UHF or 900 MHz transmitter for a nice RF linked receiver site. For link radios simplex nodes and "Hot Spots" I've come to favor the Tait T2000 mobiles. They are easy to program, well documented, lots of IO and run cool in transmit.

The above is not to say there are not a LOT of great repeater / node packages out there. The GE MASTR II comes to mind. I have to mention the Micor to keep the flack down. ;) I've built repeaters using everything from a Motorola 30D to current equipment.

Your mileage may vary.

73, Steve N4IRS

-- 
         ,,,
        (o o)
-----ooO-(_)-Ooo------
--- N4IRS was Here ---

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-- 

Skyler Fennell 

amsatnet.info <http://amsatnet.info> 

KDØWHB

electricity440 at gmail.com <mailto:electricity440 at gmail.com> 

-- 

Skyler Fennell

amsatnet.info <http://amsatnet.info> 

KDØWHB

electricity440 at gmail.com <mailto:electricity440 at gmail.com> 

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