May 2020 - Ltm - mailman.amsat.org

Scheduled automatic changes on LTM-1 and Golf?
by Burns Fisher (AMSAT) 18 May '20

18 May '20

I may have mentioned this before, but saw no answer. But the behavior of HO-107, and someone mentioning the schedule for AO-27 got me thinking about it again. This question is largely for the ops team: Suppose that the LTM-1 and Golf-Tee had the capability of commanding a schedule of operations. Let's say you could upload one or more sequences of commands labelled n. What would a schedule look like? Would it be "every n hours execute sequence x" realizing that 'n' is not terribly exact and would drift against UTC. Would it be "do sequence x entering eclipse and sequence y exiting eclipse? Would it be "Execute sequence x when I send an "execute sequence x" command? I think those are all possible, at least if the sequences are simple. No promises--there is a lot of software to do to make Golf-Tee and LTM-1 work at all, but if I get any feedback on these general ideas, I can write something up to prioritize and potentially keep in our back pocket for implementation as a "may" rather than a "must". 73, Burns Fisher, WB1FJ *AMSAT(R) Flight Software*

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SAFE mode and HuskySat-1
by Mark Hammond 17 May '20

17 May '20

Hi All, Burns has given some background, but I don't quite grasp how to find and use SAFE mode occurrences on HS-1, to help see possible correlations with other events (like the changes in FWD power). In looking at some of the data, is there a good correlation between VGA Control voltage and SAFE mode? Here is my shot at something---I think if in SAFE mode, VGA Control V will be 0. But I don't know if VGA Control voltage being at 0 means it's in SAFE mode. Meaning, how else can VGA Control V go to 0? Just looking for some telemetry points that go to "X" when in SAFE mode, so it's easier to see SAFE mode events while graphing, while trying to get some basic understanding of what all is happening. Thanks! -- Mark L. Hammond [N8MH]

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Looks like FWD power commanded down 1045u 5/15/20
by Mark Hammond 15 May '20

15 May '20

Hi all, Last night, Drew did some commanding. The bird had been going in and out of SAFE mode, so he sent several commands. I'll let him cover, but basically power to -18 and EPS to ON, as I recall. He also commanded it into HEALTH mode a time or two, but it would return to SAFE. At the send of the pass, it was in SAFE mode, and FWD power was still showing at 325mW. A quick check of the telemetry data on the web this morning showed it was in HEALTH mode, FWD power at 325mW. So about 1045utc 15 May 20, I sent some commands to try and set the power to -19, and by golly it heard me and the power dropped to about 124mW. So, at my LOS still in HEALTH mode, power showing 125mW. We'll see where it goes from here, but that has to be better on the power budget I'd think. PA cuirrent went down also, from like 225 mA to 125 mA. So that makes sense to me... 73, -- Mark L. Hammond [N8MH]

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Radio and safe mode behavior
by Burns Fisher (AMSAT) 14 May '20

14 May '20

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*

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The transmitter power
by Burns Fisher (AMSAT) 14 May '20

14 May '20

Dan and Marc, I put you explicitly on this mail, but you should have gotten a previous narrative of the weird goings-on with HuskySat this morning. If you did not, it means you are not on a mailing list that you should be on. Given that the HuskySat transmitter suddenly jumped up in power for a few hours and then went back to its old behavior, I'm hoping there might be some more info here for you to help diagnose the problem. If there is anything we can do about it for HS-1, great, but even more importantly, do we need to make any changes on Golf-Tee and the LTM to prevent this happening? I can get telemetry on as many different parameters as might be useful to you. Please tell me what info would be helpful! Thanks and 73, Burns Fisher, WB1FJ *AMSAT(R) Flight Software*

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