Probable UKHASnet launch May 21/22

UKHASnet LogoJames Coxon M6JCX reports he is hoping to launch a UKHASnet node from East Anglia this weekend.

On the UKHAS Google Group he writes:

I’ve put together a GPS enabled, temperature controlled node AJ2 which will be launched on a latex balloon (rather than pico).

Due to the pattern of the winds the aim will be to float the balloon at around 30-35 km and current predictions suggest that it’ll drift east first then turn around and come back across the UK travelling west. This should give pretty good coverage of the UK and at a push across the sea towards the Netherlands so it would be great if any UKHASnet nodes could be brought online.

The node itself will be in repeater mode as well as transmitting its own packets every 30 seconds with GPS and other data. Previous tests and flights have had a mixture of results, the EMF launch allowed for 65 km downlink range and recent tests on the IoW made a solid 2 way link over 18 km however other flights haven’t been successful. Hopefully the temperature control will stabilise the radio to stop it drifting too much (both on tx and rx) and the node will recalibrate its noise floor etc as well as reset the rx loop of the radio to stop it locking up (a previous issue). The more nodes that we can have online the better (it is even possible to setup an RTLSDR dongle as a UKHASnet gateway)

There will be a backup tracker providing a RTTY downlink on 434.300 MHz (Atlas) which will be uploaded to This will be RTTY, ASCII 7, 425 Hz shift and is an old pAVA R7 board with a RFM22 so be prepared for some drift.

Current plan is to launch around 1100 on Sat 21/05/16 though the window will be the whole weekend and launch will be from Preston St Mary, Suffolk.

Flight data will be on the UKHASnet map

I’ve made a grafana page for the node
and as always there will be discussions on #ukhasnet on freenode.



Useful High Altitude Balloon links

Balloon repeater to launch from Suffolk on Sunday

James Coxon M6JCX launching a PICO balloon on 434.301 MHz USB

James Coxon M6JCX launching a balloon carrying a transmitter payload

LAUNCH POSTPONED: Sadly due to technical issues I’m going to have to postpone this flight for a little longer – no point launching something that will definitely won’t work!

On Sunday, April 27, at around 11am (1000 GMT) radio amateur James Coxon M6JCX will launch the first UKHASnet balloon repeater from Suffolk. He writes:

Just a heads up that I’m going to try and launch tomorrow the first UKHASnet balloon repeater. The aim of the flight is to test both the concept of UKHASnet and if it works the range of the current setup. UKHASnet ( is a simple wireless network that uses licence exempt radio modules.

There are a number of nodes around the UK and also in the Netherlands which normally just communicate on a local scale, the balloon payload will act as a airborne node which will hopefully connect these networks together temporarily.

The payload is based on a ATmega328 (arduino bootloader) with a Ublox 6 GPS and a RFM69HW Radio module. It’ll be tx and rx on 869.500 MHz using FSK, 2000 bps and using the UKHASnet protocol. Balloon will be a 100g latex filled for a very slow ascent to maximise flight time, launched from Suffolk. Launch will be around 11:00, however, there are forecasts of showers so this may change.

There is NO onboard 434 MHz module and no RTTY or other traditional format, we’ll be aiming to pipe the location data onto to allow easy following. That said it’ll be possible to hear the payload with good radios and SDRs that can tune to 869.500 MHz and we would be grateful if recordings of signal can be made as this could then be played back and decoded via the hardware (there is no software decoder – yet).

More information can be found on the website and there is a IRC channel on freenode #ukhasnet where you can follow the progress. A web client is available at

As with many of my flights this is highly experimental so probably won’t work so don’t get disappointed if it gets delayed, postponed or fails!


A UKHASnet Workshop was held in March

You can see online real time tracks and frequencies of balloons at

To get up-to-date information on balloon flights subscribe to the UKHAS Mailing List by sending a blank email to this address: