[amsat-bb] ISS crew video chat equipment requirements
dan at post.com
Wed Sep 16 08:28:39 UTC 2015
I am not sure where you are located and what your plans are.
I am assuming you want an official school contact with the ISS.
First you need to apply to ARISS for permission to get an official
During the application there are options for telebridge (using a
telephone connection) and direct (using a radio)
For direct (voice only) contacts the recommendation is to have the
best station possible. The reason for this is you need to be the
strongest station for example in the USA, to try and prevent any
accidental interference from other stations transmitting.
Normally for a voice only contact you need 144Mhz 2 metres voice only
equipment FM modulation.
Normally the recommendation is to have 2 stations (main and backup).
The backup is normally a very low gain omni directional antenna such
as a 1/4 wave whip. You normally connect this to your radio with low
loss coaxial cable and ideally use a 100W radio.
For the main station what is recommended is azimuth and elevation
tracking, such as a Yaesu G-5000. The beam is normally recommended to
have circular polarisation at least 6 elements. It is better to have
the option to switch from left hand to right hand polarisation during
the middle of the contact as the polarisation can change. You also
need high power and low loss cable. The transmit and receive frequency
should be doppler corrected by computer control.
Normally you would also have an audio amplifier for the room and
projectors and recording equipment.
All these are not essential, but very important to be sure of a
reliable and long duration contact.
For video conference there is much more work. Firstly the system is
not approved for use yet, but might be very soon. Secondly only having
one station would limit the video to approximately 6 minutes maximum.
For this reason we have many video ground stations in Europe and the
plan is to send video to the school over the internet. The school
would need good internet. If it is a direct contact the school would
need to be in Europe (until USA ground stations are built)
If we assume you are in Europe, and we assume money is not a problem,
and we assume you want a direct contact, you could rely on "telebridge
video" via the internet for the video feed. If you also want you can
also receive the video at the school live and use it for some of the
contact, and also use the video over the internet.
To receive the video direct there is lots of requirements. I myself am
one of the ground stations for Europe. You need a dish, feed,
down-converter, special DVB-S satellite card and lots of time to
configure and test a computer to be sure it works. You also need a
different rotator for the dish. We normally do not recommend to use
the same rotator as the VHF antenna. The requirements are very
critical. The dish needs to be accurate to 6 degrees, which the Yaesu
G-5500 has trouble with. We are testing other rotators, but also
having trouble with these. We hope to recommend a different rotator,
when it is tested. You would want a budget of $2000 to $3000 to
consider this. If you are based in the USA there is probably no
possibility for a direct video contact in the next 1 year.
Beware organising a school contact is a lot of work. You normally need
many people and money. You also need a school with a lot of children
to be given priority. You also need to educate the children on science
and technology. It is not as simple as filling out a form.
The general information for ARISS is here:
More info here:
Lots of info here:
There is a link on that page with a form for putting in the
information for both main and backup radios.
Information on HAMTV:
Note the deadline for USA is end of October which is only a few weeks
away. You normally need to have the school principal to agree before
For Europe the next submission window extends from February 1 to April 30, 2016.
The better your proposal (better radios/antennas/more children/more
education) the better the chance you have of being picked.
If you have any questions please ask.
More information about the AMSAT-BB