[amsat-bb] Taurus-1 FM/Codec2 Voice Repeater Active

Scott scott23192 at gmail.com
Tue Sep 17 17:55:24 UTC 2019

The FM / Codec2 voice repeater on Taurus-1 went "live" today (17-Sept-2019)
with 2 passes available to stations on the U.S. East Coast.

W2RTV posted a video of the entire pass as seen from his station at

The spacecraft is clearly spinning at a high rate; my receive audio wasn't
nearly as good as Rocco's, but he's got a vastly superior antenna setup, so
that never hurts.

The repeater's uplink is normal FM on 145.820 MHz w/ a 67 Hz CTCSS tone.
High power is definitely not needed but adjusting for uplink doppler can
help extend your range.

The downlink is a Codec2 digital stream at 9600 BPSK which you receive as
USB on 435.840 MHz.  That gets you in the ballpark, anyway.  Once downlink
packets are observed, center your 15k-wide USB window on the packets and
doppler track from there.

The digital voice stream (as well as telemetry) decodes with a flowgraph in
GNU Radio.  The original telemetry decoder for Taurus-1 was produced by
EA4GPZ and is located at https://github.com/daniestevez/gr-satellites

Several of us have added to Dani's flowgraph to provide audio output now
that the repeater is active.  That hybrid flowgraph can be found at:

Note that both the original decoder from Dani as well as the hybrid
voice/telemetry flowgraph expect UDP audio input such as from GQRX.

Here is a Tweet I posted after my first contact on the repeater today with
a screen shot which pretty clearly shows how the spacecraft is spinning:

This repeater seems to work extremely well and should be way better if the
spin rate reduces over time.  Hope to hear more people on!

-Scott,  K4KDR

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