Nu börjar det närma sig för aktiviteter från ARISSat-1. I juli är planerat att den ska släppas ut från ISS. Finns mycket information nedan!
AMSAT News Service Bulletin 170.03
>From AMSAT HQ SILVER SPRING, MD.
June 19, 2011
To All RADIO AMATEURS
BID: $ANS-170.03
A few weeks remain before the planned July deployment of ARISSat-1
from the ISS. The AMSAT News Service will bring you more details
in the coming weeks. Here are some reminders to help you get your
station ready for ARISSat-1 operation.
145.950 MHz FM Downlink:
————————
FM transmissions will cycle between a voice ID as RS01S, select tele-
metry values, 24 international greeting messages in 15 languages and
SSTV images. One of the messages will be a conversation between Yuri
Gagarin and ground control. See the next news item for pointers to get
your station ready to receive the SSTV images.
435 MHz – 145 MHz Linear Transponder:
————————————-
The linear transponder will operate in Mode U/V (70 cm Up, 2m Down).
It is an 16 KHz wide inverting passband and the convention will be to
TX LSB on the 435 MHz uplink and RX USB on the 145 MHz downlink. This
mode is designed to work with low power transmitters and omni antenna.
145.919 MHz/145.939 MHz CW Beacon:
———————————-
The CW transmissions will be callsign ID RS01S, select telemetry, and
callsigns of people actively involved with the ARISS program.
145.920 MHz SSB BPSK-1000 Telemetry:
————————————
The BPSK transmissions will feature a new 1kBPSK protocol developed
by Phil Karn, KA9Q to be readable in low signal level conditions.
The BPSK data will transmit satellite telemetry.
The ARISSat-1 BPSK-1000 downlink is transmitted in SSB mode on
145.920 MHz. When the CW2 beacon on 145.919 MHz is active this
indicates that the BPSK-1000 format is being transmitted. If the
CW1 beacon on 145.939 MHz is active this indicates the backup of
BPSK-400 format is being transmitted.
Transmitting at 100 mW, both BPSK rates include Forward Error
Correction (FEC) and it is expected that modest quarter-wave
antennas with low-loss coaxial cable will provide sufficient
signal strength for decoding and display by the ARISSatTLM
software.
An audio feed from an SSB receiver to the computer’s soundcard
input is needed. An initial “Receive Only” configuration is easily
done consisting of an audio patch cable between your radio and
the soundcard. Take the speaker or headphone output from the radio
and run it into the line (or mic) input on your PC sound card.
BPSK-1000 sounds like a “shusssch” with a higher pitch than the
400 bps growl. It is difficult to tune by ear. The CW2 beacon is
used as a tuning signal for BPSK-1000. The PC and Mac ARISSatTLM
software display contains a dotted line that you use to tune your
receiver until the CW signal bumps lines up with the dotted line
on your PC screen. This will allow you to decode the BPSK-1000
signal and you will also be able to copy the CW2 beacon.
Download the Windows ARISSatTLM free ground station soundcard
demodulator and display software:
http://www.arissattlm.org/download/ARISSatTLM_050_Setup.exe
Download the Mac ARISSatTLM software:
http://www.arissattlm.org/download/ARISSATTLM.zip
The ARISSatTLM software user guide is available:
http://tinyurl.com/42uhtyf (amsat.org)
Get your color ARISSat-1 Frequency Guide:
http://tinyurl.com/4t497t2 (amsat.org)
ARISSat-1 Presentation Slides (~1MB)
http://tinyurl.com/4n4pzkm (amsat.org)
—————–
ARRISat-1 Team Pointers to Get Ready for SSTV Reception
AMSAT News Service Bulletin 170.04
>From AMSAT HQ SILVER SPRING, MD.
June 19, 2011
To All RADIO AMATEURS
BID: $ANS-170.04
The ARISSat-1 FM downlink on 145.950 MHz includes live SSTV
images as part of the cycling voice ID, select spoken telemetry
values, and the international greeting messages. Here are some
pointers to help you get your station ready to receive and dis-
the SSTV pictures transmitted by ARISSat-1.
One fun feature is that there are four SSTV cameras mounted on
the spacecraft. On photos of ARISSat-1 you may have noticed black
brackets on the outside of the spacecraft. These hold the mirrors
that reflect the light onto the lens of the cameras. The software-
defined-transponder will use the image data from the cameras to
generate the SSTV downlink.
ARISSat’s software will sequentially select a new or stored image
from one the four cameras. There are two pre-recorded images as
part of the sequence. The camera that took the the picture can be
identified by the color of the call sign in the upper left of the
SSTV image. The SSTV image will be sent down as FM audio SSTV in
Robot 36 format on 145.950 MHz about every 140 seconds.
The RF downlink power on the 145.950 MHz FM downlink will be 250mW
which is predicted to provide a link margin around 6 dB on an HT
with a ‘big whip’ when the satellite is at 15 degrees elevation. This
should be sufficient to receive SSTV pictures although you may need
to orient the whip to line up the antenna polarization.
ARISSat-1 is not stabilized so the antenna orientation is unpredict-
able and a certain amount of fading will happen. The receiving link
margin may be improved with a handheld beam such as an “Arrow”, “Elk”,
or “Cheap Yagi” antenna.
(See: http://www.wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf)
General Overview Radio-to-Soundcard Interface
———————————————
To view the SSTV downlink from ARISSat-1 you’ll need a computer
running SSTV software for your soundcard and an audio connection
between your radio and the computer.
If you are already on the air with other amateur radio soundcard
applications chances are you are ready to receive ARISSat’s SSTV
downlink with little or no modification to your setup.
The audio from the radio to the computer is the key link. An initial
“Receive Only” configuration is easily done consisting of an audio
patch cable between your radio and the soundcard. Take the speaker
or headphone output from the radio and run it into the line (or mic)
input on your PC sound card.
Setting the level is simple also as the MMSSTV software has a bar
indicator. Just adjust the sound card gain slider and/or radio volume
control so that the SSTV signal is within the center part of the bar.
MMSSTV will give you an “overflow” indication if the volume is too
high.
If your rig has a ‘Line Out’ connection this can be run to the
soundcard ‘Line In’. Using the radio ‘Line Out’ you won’t have to
deal with the interaction of the radio’s volume control with the
soundcard levels. But you will still need to use the soundcard
‘Volume Control’ to set the ‘Line In’ levels.
SSTV Software Download Sites
—————————-
There are many amateur radio SSTV software decoding applications
available. One of the easiest to use on Windows computers is the
MMSSTV program. This can be downloaded from:
http://mmhamsoft.amateur-radio.ca/pages/mmsstv.php
The Ham Radio Deluxe software package also includes SSTV operation.
SSTV software for the Mac is available at:
http://web.me.com/kd6cji/MacSSTV/MultiScan.html
[ANS thanks the ARISSat-1 Team for the above information]
