Problem Counting RR 5 Marks in LEM AGC- Apollo10

riclourenco

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Hello

I have a problem with the RR marks after the 1st burn of the LEM after DOI in apollo 10. The count of the 5 marks never appears on line R1 of the LEM AGC (in V16N45), it always stays to zero:

https://puu.sh/Clzjr/5ce1c28a6c.png

The DOI Burn was good as well as the next burn, the orbits were left with the correct aphelion and perihelion. The RR signal is good, and the CSM is at P20 for rendezvous, but the counting of the 5 marks is never done. Can you give me some help? Could I have done something wrong?


Thanks!
 

indy91

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Did you do a "Verb 81 Enter" after starting P20? That enables RR mark processing (updating the CSM state vector).
 

indy91

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For the LEM yes , but for the CSm no! That must be the problem them?

The CMC and LGC don't interact that way. You don't have to have P20 running in both for rendezvous navigation to work. In the CSM you would just need to have the RR transponder activated, but that isn't implemented yet.

What you need for the LGC is:

-RR powered up and locked onto the CSM
-P20 running
-RR mark processing enabled (V80 or V81, depending on the situation)

In your screenshot the KEY REL light is on. Could that possibly be hiding the actual V16 N45 display? That can happen if you e.g. started typing V16 but not any further. Just press KEY REL, maybe it then updates the DSKY. If not, I'll have to look at the scenario to do any further analysis on the problem.
 

riclourenco

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Okay, thank you very much, I'll get back to you as soon as I get to the NASSP. Im also going to try the V80 instead of the V81 to see if it solves the problem. I've tried the KEY REL and I think it shows the values of Lem's attitude in P20, but I'll confirm it too.
 

indy91

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I've tried the KEY REL and I think it shows the values of Lem's attitude in P20, but I'll confirm it too.

Well that's you problem then. The LGC is still trying to maneuver you to the desired tracking attitude and it won't allow any RR marks until that is done. On the 50 18 display you have to press PRO to allow the LGC to maneuver you to the attitude. During that it will display 06 18. When you get the 50 18 again after the maneuver is complete press ENTR do enable it to do continuous tracking. So this works just like the auto maneuver in e.g. P40. Also possible that no attitude maneuver is actually desired, in that case just press ENTR when the 50 18 comes up the first time.
 
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riclourenco

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After a few tries,I think I got it! :)

https://puu.sh/ClHbh/d6f669e2ee.png

Two situations happened. One of the times it was waiting for the AGC to calculate the attitude of the LEM, the display was always blank, after a short time this display appeared:

https://puu.sh/ClH9j/904a4442db.png

This display also appeared in one try, when during the F16 45 when I pressed KEY REL. I then continued to run P20 with the procedure you said, when finaly the marks appeared on the V16N45,with R1 already with one Mark. Is F06 49 normal to appear?

Thanks
 

indy91

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This display also appeared in one try, when during the F16 45 when I pressed KEY REL. I then continued to run P20 with the procedure you said, when finaly the marks appeared on the V16N45,with R1 already with one Mark. Is F06 49 normal to appear?

Thanks

The 06 49 appears when the mark would be changing the state vector in the LGC by an amount higher than a certain threshold. In that case the computer lets the astronauts decide if the mark should be incorporated or not by displaying that noun. In your case the update would be 1.0NM (and 0.0 ft/s), which is fairly large for any RR mark, but also not too worrying. As long as that only happens on the first 1-2 marks it's fine. When that display appears you have to PRO to accept it, or V32E to reject it. I'd say it's small enough to accept it.
 

riclourenco

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Thank you very much, I think I can do this well. The 06 49 only happened on the first mark! If I do a manual update of the LEM State vector with the APOLLO RTCC MFD will that help? I do this in CSM for example, when it comes time for Cis-Lunar navigation. This gives me more precise values.
 

indy91

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Thank you very much, I think I can do this well. The 06 49 only happened on the first mark! If I do a manual update of the LEM State vector with the APOLLO RTCC MFD will that help? I do this in CSM for example, when it comes time for Cis-Lunar navigation. This gives me more precise values.

Well, if it is only a small initial error, as you got, I would just let the LGC do the job. After all that is why it had a RR and an eloborate navigation scheme with Kalman filter in the computer. To correct these small errors. If the CSM and LM state vectors in the LGC are perfect all the time then the LGC doesn't have much to do. We wouldn't want it to get bored, right? :lol:
 

riclourenco

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Right :D ! Okay thank you very much, I will continue the mission and see if I can reach the CSM :) . Merry Christmas indy91!
 

sw34669

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i'm also struggling with this at the point of just after LM DOI
I cannot get the signal to ping up
the last attiude the checklist left the CSM iin was not pointing right at the LM so i fixed that but for the life of me i cant get the signal meter on the LM to increase.

Roughly speaking what should I be doing, is there something on the CSM that's implemented now that i havn't turned on that may not have been included in the checklist ? What switches should i check ? I have the RR circ breaker in and the yellow no signal light is on and the checklist set the rotary radar switch to LGC. I've also put it into slew and tried to aquire the signal and jumped between ships to ensure they are pointing at each other. I'm here . I've taken so long i've missed the PDI burn i think.

1612460488257.png
 

indy91

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Your Test Monitor is in the wrong setting. You need RR - AGC, (AGC is Automatic Gain Control in this case). You are looking at a voltage from the Landing Radar, which is probably unpowered at the moment.
 

sw34669

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ah naughty checklist mfd :)
with the other rotary not in slew do you use pitch and roll to get a signal or does the slew switch work
is success having the meter rise and the no track light go out?

also the slew UDLR button has a Left clickspot the size of 1 angstrom :)
 

sw34669

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still unfortunately unable to get this to operate unless i switch the right dial to slew .... i got it locked on after 20 mins and then hit auto to improve the signal. The second I switch it back to agc, the signal drops to zero and i lose lock. both craft are stationary but it's night so any external view is 100% pitch black. checking the pitch of each they are pointing straight at each other and 2 km apart. This is the problem, im sure its a simple thing if you know exactly how to do it. what could i be doing wrong ?
 

n72.75

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Is the transponder on in the CSM?
 

sw34669

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dont know i read something on another thread that the xponder wasnt implemented last year so not sure if thats still true
i've been working on the assumption that if i followed the checklists in the LM and CSM both crafts would have the right settings, it seems thats not the case

I have them 500m apart at the moment and if i get them really really really aligned with slew at each other i get a small signal. I can then hit auto and get a stronger signal, but, when i switch to LGC where it should be for the radar test the antenna on the LM just goes skyward and i lose the signal.

The move of the CSM and LM after docking in the yellow text dont point them at each other.

Where should i look for the transponder in the CSM and any ideas why, when switching back to LGC it all goes wrong ? The radar doesnt pitch forward much and in darkness you dont notice that. I spent this afternoon flicking through a few of the 1000 page manuals .
1612478190307.png
 

n72.75

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The rendezvous radar transponder implementation was one of my summer projects in 2020.

The minimum range that it will work at is 80ft, since you're out beyond that you should have no trouble getting a lock.

To activate the transponder these two switches need to be set like this:

rndzxpndr1.png



Power for the transponder comes from a circuit breaker that connects it to the flight bus; the flight bus has two CBs that are powered from main A and B, so all three of these should be pushed in like this:
rndzxpndr2.png


The small signal strength you're seeing is my implementation of radar skin reflection; in actuality I don't think the LM radar would pick this up, only the signal from the transponder, so I'll probably fix this in the near future and you'll only see a signal back from the CSM when the transponder is on.

There's a phase lock that takes 1.3 seconds on the CSM side, and them the LEM will take ~12 seconds to give you a range lock(bur range rate and auto tracking should kick in very shortly with the transponder on).
 

sw34669

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thank you ,ive checked the csm in my active scanario and all switches are the same as you show above. The circ breakers are also in . Whats different is the voltage.

1612490372868.png

1612490470235.png
 

sw34669

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where should i put the spare AAs :)
 
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