Can U4B channel be spoofed? #picoballoon #u4b


Klaas, VA3ERW
 

Finally getting back to preparing for my first-ever balloon flight.

On the tracking page of QRPLabs, I saw to my surprise that one of my U4B beacons was seen in the air a few months ago, although I haven't moved it out of the house. No HF antenna has been put on either, just the GPS antenna.

Could it be that someone else is able to take over a channel and S/N?

Klaas


VE3KCL
 

Hi Klaas
I believe channel 353 the one you chose, should be transmitting on 14097140    with a tele of 1x7xxx with wspr tx starting on minute 4.
If you look at your tracking page which shows the last spot on Sept 22 you will see the frequency is different 14097027
If you look at wsprnet and search your tele as 0_7* and unclick the box for exclude special callsigns you can see what tele is being used by other picos.
There are others pico balloons with different tele systems that could fall on your particular channel if you are not using it.
It is always advisable to check to see if the channel is in use and pick one of the 3 in the firmware that is not being used before the flight... I assume that is what other pico balloon guys do before a flight too.
I am not sure if Hans has implemented the exclusive frequency filtering yet, but there are still a lot of channels to choose from.
Also bad spots can be generated by the limited number of hash combinations in wspr and usually the spot is bad if the telemetry is reported as a Maidenhead 6  because the U4B only transmits Maidenhead 4.
So I would suggest that you check if the channel is clear before the flight to not have a problem, as the frequencies are shared.
73 Dave VE3KCL


Klaas, VA3ERW
 

Thanks for the advice, Dave. I wasn't aware that channels were offered to different U4Bs.
73 Klaas VA3ERW


VE3KCL
 

Hi Klaas 
I believe the original idea was to reserve the channel frequency for testing and the duration of the flight. 
If however you are not testing or flying the frequency would then become clear.
If you look at the U4B tracking grid a number of U4Bs have flown or reserved a channel but the frequency is dormant.(like yours was since September)
I believe the original idea was to clear the channel if it was not being used after a month of dormancy.
It is possible that an non U4B pico was using the channel that you previously reserved and seeing the frequency was clear started using it.
What I do and suggest you try, is run the U4B from a battery for a week or more before the flight. ( even if you are the only one receiving the signal)
Dave VE3KCL


Klaas, VA3ERW
 

Thanks Dave, will do that!
Klaas VA3ERW