I plan to launch a pico balloon in the next two months that will probably go around the world several times. I would like to download some data about temperature pressure altitude and velocity as a function of time. The format would be AX.25 and be in the 2m ham band. It is easy to predict where and when the balloon will be during the next day. Could I schedule one or more stations to download the data?
[Pico Balloons by K9YO (Pico Balloons by K9YO)
Ken K9YO
SatNOGS is not set up for this.
If you are transmitting on the 2m APRS frequency (for the particular country that you are over), then you any telemetry will be picked up by stations in range and uploaded to the APRS-IS network.
For an APRS transmitter, this would be your most reliable method of getting data back.
However, using 2m APRS is generally a poor idea for circumnavigating balloons. The pico-ballooning community has moved on to using WSPR, usually on the 20m band, for these types of flights. The amount of telemetry you get is still very limited, however it can still be received when your payload is far outside VHF coverage range.
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Thank you for your reply. I have noticed significant differences between the balloon altitude predictions by NOAA and the WSPR data. I am working on a study to get additional data from the balloon for detailed comparisons with the NOAA predictions. I have designed and built a balloon transmitter that can transmit both HF WSPR and VHF AX.25.
Like you said, WSPR is excellent for worldwide position reporting but is limited to 25 bits in a 2-minute period for any other data. APRS is also good for short position information and limited data. Because a balloon will be received by all the APRS receivers for hundreds of km it should not be used for a significant amount of data. My balloon will use APRS and WSPR for location and a limited amount of data.
In addition, I would like to use a frequency different than the standard (local) APRS frequency to download about 5 minutes of high precision, detailed data near the end of the local solar day. The location and time of day for the download are easily predicted and could be captured with a few omni directional SATNOG receives in that area. I had discussed this idea with a representative of SATNOG at the Dayton convention who gave the impression that it was worthy of additional discussion.
Please reconsider your decision. I have been flying pico balloons for the last 4 years and have given talks on the topic to several organizations.
Ken K9YO – SATNOG station 2579 PhD
Honestly you would be fine doing this kind of thing on APRS, especially if you’re only doing it once a day like you say.
Just don’t use a digi-peating path and spread it out a little bit and I doubt you’d cause anyone grief. You’d have a lot more luck with this approach than hoping that you’re within range of a SatNOGS station when you need to downlink.
The main issue at the moment is I don’t think SatNOGS is setup to do this kind of collection. It’s very geared towards tracking something in orbit with a TLE, not collecting on an arbitrary frequency at an arbitrary time. Sure, it could be added, but it’s not something I’d expect to happen quickly.
I believe there is an existing APRS transmitter that will switch APRS frequencies depending on the country it’s over.