http://anserver1.eprsl.wustl.edu/anteam/me...b_resources.htm
I like little interesting data sets like this - they're wonderfull to look at.

These ones cover the off-baseline frequency of Odyssey during a UHF pass ( from a baseline of 400Mhz ) - and if data is good or not (0 - good data..no, I dont know why either)

They were used to help locate the rovers early on - but I think they also show a good profile of what a UHF pass is typically like. You can see the data drop out twice, one presumes as the Pancam Mast, and the LGA obstructed the line of sight from UHF mast to Odyssey - and again right towards the end briefly, perhaps because of HGA.

Interesting little graph anyway.

What about is that the UHF antena should be sitting on the top of Pancam Mast for MarExo since its small UHF stick is on the top base of rover. That is to avoid the drop signal due to the obstruction of near objects.

Rodolfo

I remember seing the UHF mast for MSL being on top of the equiv. of the pancam mast, but recent drawings I've seen dont have that anymore.

Some of the other passes show fairly long blackouts - perhaps HGA getting in the way etc.

Doug

I think that the technical challenges to put an UHF on the top of pancam mast are :

1) Larger altitude and it might become an limitation for keeping purposes inside of landing capsule.
2) In some instances, the pancam must have two joins instead of one join as ones of ExoMars which helps to reduce the half the size of the pancam. Hence the ExoMars' pancam is taller than the ones of MSL with only one joint on the base.
3) The UHF antena must have a fixed size and if there is technical problems related to keeping inside the cruise capsule, it would be solved with a extend/retract mechanism that will imply some costs and weight.
4) The last word, if the temporal communication interruption due to the physical obtruction is neglible, than it would be wiser and practical to put the UHF on the top of rover's surface.

Anyway, the MSL and ExoMars will have a much wider bandwith communication capability and the drop signal due to the interruption caused by a physical obstruction might be of a little importance and so it will permit a simpler design and might save some hundreds grams (US$ 40,000.00 - 20,000.00 per hundred of grams)

Rodolfo

Well, perhaps another reason, if the Pancam mast doesn't deploy then you've lost your UHF too.. I suspect the main reason is simply space - not enough space within the enclosure for the UHF to not have to be retractable/foldable, with all the resulting complications considering the top of the mast rotates in elevation *and* the mast has to be hollow for the TES light path.

Airbag