[amsat-bb] Taurus-1 FM/Codec2 Voice Repeater Active
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!
More information about the AMSAT-BB