[sarex] Re: further late reply regarding ISS simplex

Ransom, Kenneth G. (JSC-OC)[BAR] kenneth.g.ransom at nasa.gov
Fri Aug 11 06:09:07 PDT 2006

It sounds like your issue is not that split frequencies are bad but that
multiple uplinks makes it difficult for the crew to listen to one
uplink. ITU region regulations for ground station operations are the
culprit. Space has no borders but Earth does so have of the problem is
getting everyone to agree on a single uplink. Not everyone in the world
has the same frequency allocations nor do they use the available
spectrum in their region the same way.

The issue is not the 20-30 miles but the number of callers in the 2000
km wide footprint. The station has to listen to all of them. Since you
can't hear all of them, it becomes difficult to know when someone is
talking or not without guidance from the station operator.

In the MIR days, the crew did not have the luxury of near full time
satellite communication that provides voice, email communication and an
IP phone that lets them make phone calls. If the MIR crew wanted to talk
to someone, they needed to use the ham radio or the Russian VHF space to
ground system. The ISS crew has plenty of options to choose from when
they want to communicate and it depends on the personality of the crew
as to which ones get utilized.

Kenneth - N5VHO

-----Original Message-----
From: sarex-bounces at AMSAT.Org [mailto:sarex-bounces at AMSAT.Org] On Behalf
Of McGrane
Sent: Thursday, August 10, 2006 6:43 PM
To: Manned space BBS
Subject: [sarex] further late reply regarding ISS simplex

Greetings from patrick N2OEQ

Despite support of the present frequency scheme for the ISS I still wish
to disagree with the policy of split operation with different phone

Back when the MIR was up, the russians operated simplex and left the
radio on to listen for callers.
On several occasions, I called the MIR according to my tracking program
and was rewarded several times with a response.

With two different uplink frequencies, the astronauts are less inclined
to leave the radio on to listen for callers. 

When there were several callers here on simplex responding to a CQ call
from the MIR, we acted civilized and took turns and everyone made
contacts so I dont buy the absolute need for split operation.
Besides, how many callers could there be within 20 or 30 miles up to the

We've had years of robot like amateur radio on the ISS. How about
loosening the ties!

Thanks for the soapbox..... pat

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