[amsat-bb] Ham Video
gaston.bertels at skynet.be
Sun Jan 26 10:35:10 PST 2014
HamTV Bulletin #5
January 26, 2014
Ham Video Commissioning Blank Transmissions
As announced December 22, 2013 the Ham Video
transmitter is onboard the International Space
Station and stored in the Columbus module. It is
slated to be installed February 5, 2014 by
Michael Hopkins KF5LJG. Hopkins will also install
the camera and the supporting Bogen arm.
The Ham Video transmitter will be connected to
the ARISS 41 antenna and to the KuPS power
supply. The installation procedure comprizes a
check of the electrical connections. The
transmitter will be powered on and will transmit
a signal on 2.422 GHz. This check will be very
limited in time, just enough to verify that the
control LEDs are nominal. Then Ham Video will be
powered off, ready for the first Commissioning Step.
January 23 and 24, Commissioning Simulations were
again performed by ESA, in collaboration with
ARISS. The ARISS Team, in charge of receiving the
signals during the Commissioning, worked with
B.USOC, simulating the four scheduled
Commissioning Steps. The procedure was an update
of the Simulations performed 5-6 September 2013,
as reported in HamTV Bulletin #2. (All HamTV
Bulletins are archived at <http://www.ariss-eu.org/>www.ariss-eu.org ).
The four Commissioning steps are scheduled
February 8, 15 and 16 and March 5. These dates
are still to be confirmed and this depends on the
signature of the Flight Rules relative to Ham Video (see HamTV Bulletin #4).
Blank Transmissions will start immediately at the
conclusion of Commissioning Step 1 and will
continue till Commissioning Step 4. This means
that the Ham Video transmitter will operate continuously during 25 days.
The DATV signal parameters will be:
* Downlink frequency: 2.395 GHz
* DVB-S standard (QPSK modulation)
* Symbol rate: 1.3 Ms/s
* FEC : ½
* Video PID = 256
* Audio PID = 257
* RF radiated power : approximately 10 W EIRP
Ham Video will operate with a Canon XF-305
camera, but the camera will be turned off during the Blank Transmissions.
A « blank » DVB-S signal contains all the data of
normal DVB-S. The information tables describing
the content and the content itself, i.e. the
video (black) and the audio (silence), are the
same as for the image and the sound produced by a camera.
Receiving a black image and silent sound may seem
uninteresting but, from a technical perspective,
the digital signal offers an important source of information.
The decoded signal provides many data :
* the video stream can be measured (Tutioune + TS reader)
* the audio stream can be measured (Tutioune + TS reader)
* the DVB tables can be decoded (satellite
receiver (Set Top Box) or Tutioune or TS reader or VLC
The DVB tables mention the PIDs (content
identification numbers) as well as the SDT
(Service Description Table) with the TV channel name, which will be « HAMTV »
Even without decoding, several measurements of
the received signal provide valuable information:
* analogic HF signal strength (dBm)
* analogic Signal/Noise ratio (dB)
* digital Signal/Noise ratio = MER (dB)
* error/correction ratio = Vber, Cber
* validation of the received transport stream = TS
Ground stations with S-band capability can
provide valuable information, which will be much appreciated.
Basic data such as:
* noise level without signal
* AOS time (UTC)
* maximum signal level during pass
· LOS time (UTC)
can be reported by ground stations without the
need of special DATV hard- and software.
ARISS is preparing a Ham Video Internet Reporting
Program for collecting reception data from volunteering ground stations.
These most needed reception reports will be gratefully accepted.
Basic DATV receiver
A Set Top Box or a Television receiver with
satellite tuner can be used for receiving Ham
Video signals during a pass of the ISS.
When scanning the 2.395 GHz frequency, the DVB
stream can be decoded. When this is successful,
the channel name « HAMTV » will appear on the TV screen.
Windows computer with TechnoTrend TT S2-1600 card and Tutioune software
A Windows computer with TT S2-1600 receiver card
can be used for Ham Video reception. See appended
Block Diagram of N6IZW Station.
The Tutioune software, developed by Jean Pierre
Courjaud F6DZP, measures and records the Ham
Video signals second per second:
* HF signal level
* digital Signal/Noise level = MER (dB)
* error/correction = Vber
· validation of the received transport stream = TS
The recorded file can be examined and forwarded to ARISS.
Better even, the data can be forwarded during an
ISS pass to the TiouneMonitor on
website. In other words, the data can be observed worldwide, real time.
Tutioune also shows the constellations during
signal reception (see HamTV Bulletin #4). The TS
stream can be recorded, but this is less
interesting since richer information is already available.
Tutioune also decodes the DVB tables and provides
the PIDs and the channel name (« HAMTV ») recovered from the SDT table.
Gaston Bertels, ON4WF
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