Hacker News Reader

A sat tracking program I have shows ISS passing almost directly overhead in about 40 minutes. How would the downlink frequency vary due to doppler shift as it transits from local horizon to local horizon?

View on HN

Good question. Some info on tuning for Doppler shift:

https://www.qsl.net/ah6rh/am-radio/spacecomm/doppler-and-the...

Thank you, that was very informative. Seems like the calculations are pretty straight forward. I need to see if I can create my own charts like that.

The open source software gpredict can do this live for you.

Short answer - by one or two of the smallest steps on a typical handheld, starting above the nominal frequency and ending below it. A bit more than that for UHF downlinks.

Reply on news.ycombinator.com