[App_rpt-users] app_rpt from MP3 stream was remote receivers questions

Steve Wright info at meshnetworks.co.nz
Sat Mar 5 14:13:28 EST 2016

On 05/03/16 06:00, mike at midnighteng.com wrote:
> RTL-SDR have no front-end rejection. While I like to use them for many things, They
> make terrible choice in repeater work.

No receiver has any front end rejection until you had a front end, which 
we'll do.

> If your RPTR TX'r is in the same band, watch it totally de-sense that RTL-SDR.

No, as stated, these are remote receivers.  There's no other noise 
generating equipment on site except the solar panel regulator.

> What good would it be.
> Better off with a tyt/boafeng HT etc. And that's not giving those any credit.

Not a silly idea actually.  A simple coax front end cavity,  or notch to 
target the image might be in order.

> You do need some scheme to vote/select the most valid one (to the core site) if it
> is different PL etc.

All built in to app_rpt isn't it?

> FYI There are RTCM /voter systems for app_rpt if you want to do it right.

Too expensive when building a three repeater, six receiver distributed 
system.  That's 24 RTCMs.

> Since there is a left and right definable audio channel, I had always thought you
> could double-up on the dongles but never tried it.

My understanding is that cannot be done.  Dongles are cheap as chips, so 
that's false economy.

My original query as follows ;

> For remote receivers, is there any work being done on using RTL SDR
> rtl_fm multiple-instances on one dongle, as multiple app_rpt IP
> connected receivers?
> I ask, because it seems that a remote (RX only) site can host as many
> receivers as I can shoe-horn in the box, and as many as I can add
> solar-panels to feed.
> It also seems, that I may as well host neighboring areas' remote
> receivers, and they host mine - for even larger coverage.
> It just seems a stack of ten GM300s in there is the hard way, and it's a
> lot of current draw too.

There is a group of aviation-monitoring enthusiasts who have cracked the 
multi-channel thing, so it seems to be just a matter of feeding multiple 
MP3 streams to multiple app_rpt daemons.

Anyone know how this works?


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