INTO SATELLITES WITH AO85
following guidelines are provided for users:
power should be on the order of minimum 200 W EIRP for full quieting
at lower antenna elevation angles. Your mileage may vary.With an
Arrow, 5 W has been used successfully to make contacts.
is important. The satellite antennas are linear. So, if you are
using linearly polarized antennas, you will need to adjust
throughout the pass. Full duplex operation facilitates these
adjustments while transmitting and is highly recommended.
downlink is very strong and should be heard well with almost any
antenna. Downlink audio is 5 kHz deviation, as expected. Many will
perceive that the audio is "low." This is an effect of the filtering
below 300 Hz, which provides for the DUV telemetry, coupled with any
noise on the uplink signal resulting from lack of full quieting or
being off frequency. That makes for less fidelity than a typical
receiver in terms of audio frequencies passed.
(downlink) frequency varies with temperature. Due to the wide range
of temperatures we are seeing in the eclipse cycle, the transmitter
can be anywhere from around 500 Hz low at 10°C to near 2 kHz low at
frequency has been generally agreed to be about 435.170 MHz,
although the AFC makes that hard to pin down and also helps with the
uplinks that are off frequency.
the most notable observations about AO-85 are an apparent lack of
sensitivity and difficulty in turning on the repeater with the 67 Hz
CTCSS when it is not yet activated, or holding it on by the presence
of the CTCSS. We have determined a probable cause for the
sensitivity issue and while that can't be fixed on AO-85 we are
taking steps to prevent similar issues on the rest of the Fox-1
CubeSats. The tone detection threshold along with the receive
sensitivity issue makes it hard to bring up the repeater. This is
being addressed by adjusting the values for a valid tone detection
in the other Fox-1 CubeSats now that we have on orbit information
about temperatures and power budget.
important to remember that science is the reason behind the Fox-1
satellites. Not only does science help with the launch cost, it
provides a great amount of educational value both from the science
payload and in amateur radio itself. The data-under-voice (DUV)
telemetry is an excellent way to provide the science without
sacrificing the use of the satellite for communications, which would
be the case if higher speed downlinks were needed. DUV provides
constant science as long as the repeater is in use, which in turn
provides more downlink data for the science - a mutually beneficial
AMSAT-NA's first CubeSat. Many new techniques are incorporated and
lessons will be learned, as with any new "product."
Project is a series of CubeSats. A total of five will be built and
flown. Launches are scheduled for three more, and a new NASA CubeSat
Launch Initiative proposal will be submitted for the fifth. AMSATNA
will incorporate changes from what we learn in each launch, to the
extent possible, in subsequent Fox-1 CubeSats.