An interesting discussion at the diyAudio forums about the quality of NASA audio. Panomaniac writes:
So what’s up with the rotten audio from the NASA missions? It has bugged me for years. Ever notice how bad it is? Why?
Now the old moon mission maybe I can understand, but the ISS and shuttle stuff? They are in low earth orbit, for crying out loud. How hard would it be to get pristine audio back down to earth?
A geostationary orbit, where the communication satellites sit, is 35000 Km above the earth’s surface, and they can beam 100s of SD and HD video and audio channels. The Space Station is only about 350Km up and they can’t get better than 1934 radio quality.
There’s also a summary at EE Times. So what do you think? Why is NASA still so lo-fi? We can put a man on the moon, but we can’t understand him when he gets there.
(and yeah, it’s an astronaut with a banjo — happy Friday!)
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I agree. Come on NASA! Join us in the 21st century.
They use the K-Band technology….
Also, they believe on a good principle, if it ant broke, don’t fix it.
It’s probably because they run it though a whole pile of band-limiting and compression before transmission and transmit in analog to help keep it intelligible even with low signal strength and interference so they can always talk to each other.
If you’ve ever tried to carry on a phone conversation with someone on a cell phone who is right on the edge of coverage, you’ll know how hard it is to understand digital voice when you start losing data.
Now compare that to some of the voice-DX hams.
i think they’re going with the “if it isn’t broke don’t fix it”
i don’t think they sound too bad, i like it, you know you’re listening to astronauts
Along the lines of why we still use AM for VHF aircraft communications. Yep, FM is better sounding, but AM doesn’t become as unintelligible during picket fencing. AM also just gets weaker volume as the signal degrades, instead of cutting out altogether. If someone’s crashed into the brush and has a still working radio, you can hear their attempts to transmit far beyond the capabilities of FM.
As to beaming to Geostationary, you’ve got a small target a long way out to hit and the delays for real time voice communications just stink. Compress the heck out of it and pipeline it through lower orbit satellites and ground stations for better communications (HiFi sound quality has very little to do with this).
i’m pretty sure they are using something similar to dama (demand assigned multiple access – which allows multiple users on what once was a single wideband satellite chanel.) sat com, which only has a 5 k bandwidth, the reason they may use it is because there is more valuable data to send rather than upping audio quality that they can deal with.
a single wideband channel is 25k, why waste it on unnecessary audio quality?