streaming RTL SDR appliance?

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streaming RTL SDR appliance?

Steve Wright
Greetings!

I'm looking for a working config for ;

1.)  A repeater with multiple remote voting receivers, and
2.)  A multi-channel RTL SDR streaming receiver

Does anyone have a working tar.gz config, or an RPI or VM image?

Alternatively, can someone point me at the docs for this.


Thanks greatly,
Steve



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Re: streaming RTL SDR appliance?

Rob Janssen
Steve Wright wrote:

> Greetings!
>
> I'm looking for a working config for ;
>
> 1.)  A repeater with multiple remote voting receivers, and
> 2.)  A multi-channel RTL SDR streaming receiver
>
> Does anyone have a working tar.gz config, or an RPI or VM image?
>
> Alternatively, can someone point me at the docs for this.
>
>
> Thanks greatly,
> Steve
>
Hi Steve,

This is our configuration for a RTL SDR remote receiver:

###############################################################################
#
# Configuration file for the RemoteTrx application. A remote transceiver
# for the SvxLink server system.
#
###############################################################################

[GLOBAL]
TRXS=NetRx_EXP
TIMESTAMP_FORMAT="%c"
CARD_SAMPLE_RATE=48000

# Experimental 70cm receivers via DVB-T stick

[NetRx_EXP]
TYPE=Net
RX=DdrRx_EXP
TX=NONE
LISTEN_PORT=5210
FALLBACK_REPEATER=0
AUTH_KEY="typesomerandomstringhere"

[DdrRx_EXP]
TYPE=Ddr
WBRX=WbRx1
FQ=431600000
SQL_DET=SIGLEV
SIGLEV_DET=NOISE
SIGLEV_SLOPE=18
SIGLEV_OFFSET=11.5
SIGLEV_OPEN_THRESH=10
SIGLEV_CLOSE_THRESH=5
DEEMPHASIS=1
PREAMP=-3
PEAK_METER=0

# Realtek DVB-T stick on USB

[WbRx1]
TYPE=RtlUsb
SAMPLE_RATE=960000
FQ_CORR=64
#GAIN=29.7
PEAK_METER=0

This receiver works on a single frequency, but you can add additional receivers by copying the NetRx and DdrRx
sections under a different name and change RX, LISTEN_PORT and FQ. Add the names of the extra sections to
the TRXS line near the top, comma-separated.

We run the above config on a Raspberry Pi 2 or 3 or Cubieboard 2, when you have a PC you can use the higher
sample rate 2400000 and have wider bandwidth and better performance.

The FQ_CORR is the frequency correction that you have to determine for every stick, you can to that using other
SDR software or you can temporarily put the receiver in SSB mode (add MODULATION=USB to the Ddr section)
and tune your transmitter up/down in small steps to find the signal, adjust the FQ_CORR, restart the software and
try again until you are close to zero-beat on SSB.

Everything is documented in "man 5 svxlink.conf" but it may be easier to start from an example.

To have a repeater with multiple receivers and a voter, just start from a normal repeater configuration but add a
Voter section like this:

[Voter]
TYPE=Voter
RECEIVERS=list,of,receiver,names,separate,by,comma
VOTING_DELAY=0
BUFFER_LENGTH=0
REVOTE_INTERVAL=100
HYSTERESIS=20
RX_SWITCH_DELAY=250
SQL_CLOSE_REVOTE_DELAY=200

Specify this voter as the receiver in your repeater section, where you originally had the name of your local receiver:

[RepeaterLogic]
TYPE=Repeater
RX=Voter

Your local receiver name goes in the RECEIVERS line of the Voter, and other (remote) receivers can be added
with a section like this for each receiver:

[Rx_Name]
TYPE=Net
HOST=ip.ad.re.ss
TCP_PORT=5210
LOG_DISCONNECTS_ONCE=1
AUTH_KEY="matchingauthkeyoftheremotereceiver"
CODEC=OPUS
OPUS_ENC_FRAME_SIZE=20
OPUS_ENC_COMPLEXITY=10
OPUS_ENC_BITRATE=32000
OPUS_ENC_VBR=1

That is basically all there is for a repeater with multiple voting receivers.

Rob

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