I have done a lot of examination of the telemetry sent today from HS-1.
This is a narrative of what I believe to be the sequence of events.
As most of us are aware, HS-1 has been operating at about 17mW of power for
several months without the transponder on. Turning up the digital gain by
3dB or more had only a minimal effect (maybe up to 18 or 19 mW). Turning
on the transponder last weekend had little effect. It's not clear (to me
at least) whether the transponder downlink power maxed out at 20mW or so,
but at the very least, we know that a strong uplink signal appeared to
modulate and/or take power away from the beacon.
At approximately 0456z today the power (as read by the telemetry) jumped to
over 300mW. This does not appear to be related to temperature, although it
should be no surprise that the RxTx temperature showed a rise shortly
afterwards. In addition, there was no obvious change in bus voltage
preceding the occurrence.
At approximately 0720z today, 14May, HS-1 went into safe mode. This is
likely because the bus voltage went below the auto-safe threshold (there is
no other reason that this will happen autonomously--I don't believe that
the UW components can command it), although looking at the bus voltage
graph, it is not especially low at that time. It could just have been a
pulse that happened at a different time from the telemetry being read. In
the meantime when the beacon was on, the radio power was still high
(although varying--this could easily be telemetry data collection issues)
HS1 came OUT of safe mode back to health mode at about 0854z. Again, this
is probably related to the bus voltage, but I just can't see it on the
graph. This made little difference in the output power.
At about 1120 there was a brief bus voltage drop from about 6.2 to about
5.8V. which sent it into safe mode again. In the middle of this safe mode,
the RF power dropped back to 20-ish mW. Health mode was restored around
1250, and the RF power remained at 20-ish mW.
Between 1252 and 1255, 10 commands were received. All the commands visible
in the telemetry were CAN commands, which I assume were to turn on the
EPS. We did not have enough telemetry to see all 10 commands, but Drew
states that he sent telemetry power commands, so those were doubtless the
ones that did not show. Indeed the telemetry power appears to have dropped
a bit, consistent with reducing digital gain.
rc_eps_batt_5 and batt_2 are now sending telemetry, indicating that the
restart of the EPS was successful.
73,
Burns Fisher, WB1FJ
*AMSAT(R) Flight Software*
