[amsat-bb] Is this common? Better audio w/ delay before speaking?

Scott scott23192 at gmail.com
Wed Jun 7 04:55:00 UTC 2017

Hey everybody!

I had a very high pass of LilacSat-1 tonight and took the opportunity to
try to see how I could improve the percentage of my transmissions that the
satellite would digitize & repeat onto the downlink.

Wei from the project team at Harbin was kind enough to call to my attention
that there should be a short delay ("a few hundred ms") before speaking so
that the CTCSS decode could process.  Following that period, the audio on
the uplink would be passed on to the satellite's receiver.

As I tested various techniques while transmitting tonight, it became pretty
obvious that I was getting MUCH better audio on the downlink with a full
2-second delay before speaking when I keyed the mic.

I was just wondering if anything like this had been seen on other
satellites over the years. (or land-based systems, for that matter)

I realize that we're treading on new ground with this satellite processing
the uplink audio with an on-board computer for transmission as a data
stream on the downlink, but the front-end is still dealing with a standard
FM carrier and PL, so I was curious if a longer-than-expected delay had
possibly been seen elsewhere over the years.

Just trying to learn as I go.  Thanks for any feedback.

Here's a sample of the quality of downlink I was seeing with that 2-second


-Scott,  K4KDR

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