I talked with a NWS employee this week and he confirmed the 1100 and 2300 UTC launch times from Sterling. In an early posting it looked like your were receiving these on 401 MHz. Some internet sources indicated that 403 MHz was used. I did hear some weak data bursts on 403 MHz yesterday around 1545 UTC, but I don’t know what they came from - a radiosonde or perhaps some local device.
Yes, the Sterling radiosondes are typically around 401.015 MHz (they vary a little, and of course drift with changes in temperature as the balloon ascends). They used to use 1680 MHz, which was much more difficult to pick up.
I have also picked up a radiosonde on 402.3 MHz, last summer I think (check for logs on this board), the path was from Dulles, I suspected it was some sort of an air quality / ozone sensor, I will check for it again. There could well be other launches, I think there could be one from Aberdeen Proving Ground, but as it is east of me, tougher to catch here. Regarding your 403 MHz reception: 1545 UTC is somewhat late to be still hearing an 1100 launch, so it could be something else, but certainly worth looking into. I'll try to check out the entire 401-403 MHz band later this morning and see if anything appears. The winds this morning should produce a good path for Sterling's launch for my reception here.
The other night I had a second radiosonde about 10 or 15 kHz lower than Sterling's, too weak to get any decodes. I need a slightly better antenna for 401 MHz (I am using a discone pulled up into a tree now). A Yagi would have more gain and directionality, but there is no way I could get it up as high, so I am not sure how it would work overall. I've been considering building a QFH for 401 MHz, which I should be able to get as high as the discone.
Does your NWS contact know of a list of all of the radiosonde frequencies and types used by each of the launch sites in the USA?
Topic: Sterling Radiosonde Launch Evening 1 April 2019 (Read 3857 times)
