[amsat-bb] Re: Funcube-1 is +10 kHz on the uplink?

PA3GUO pa3guo at upcmail.nl
Sun Dec 29 14:28:20 PST 2013

Thanks for the explaination Wouter. It sure is a fantastic transponder!

Henk, PA3GUO


ps: indeed as stated everywhere: 5W uplink is more than enough for a strong



Van: Wouter Weggelaar [mailto:wouterweg at gmail.com] 
Verzonden: zondag 29 december 2013 22:53
Onderwerp: Re: [amsat-bb] Funcube-1 is +10 kHz on the uplink?


Hi Henk,

What you are seeing is the combined effect of various oscillators drifting
over temperature and some static offsets present.

It is not so easy to have these offsets quantified as static numbers.

The oscillators were designed to be extremely low power, and temperature
compensation is therefore limited. we do not have the power on board for PLL
based frequency generation. With the current state of the art, this is
possible, but not when the circuit was designed.

The power budget of a one Unit CubeSat is challenging, and FUNcube is the
first 1U CubeSat to include a linear transponder.

At the moment we are nice and power positive, but the system was designed
with the degradation of the battery and solar arrays in mind.

So in the end, I am afraid you will have to guesstimate based on

Wouter PA3WEG

FUNcube transponder designer


On Fri, Dec 27, 2013 at 10:05 PM, PA3GUO <pa3guo at upcmail.nl> wrote:

Just wondered if I saw this observed/reported already:

When for the Funcube-1 transponder using:
435.140 MHz uplink  (LSB)
145.960 MHz downlink (USB)
I still need to add another 10kHz on the uplink (making it 435.150 MHz).

Can anyone else confirm (or counter :-)) this ?

Henk, PA3GUO
The Netherlands

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