Interesting stuff on Twitter this morning…….Dan
Interesting stuff on Twitter this morning…….Dan
The amateur satellite service is a radio communications service using amateur radio stations on satellites. (E1D02) In the amateur satellite service, the satellites are called space stations and are remotely controlled by telecommands.
Only 40m, 20m, 17m, 15m, 12m and 10m are the amateur service HF bands have frequencies authorized to space stations. (E1D07) 2 meters is the only VHF amateur service band that has frequencies available for space stations. (E1D08) 70 cm, 23 cm, 13 cm are the amateur service UHF bands that have frequencies available for a space station. (E1D09)
One special provision that a space station must incorporate in order to comply with space station requirements is that the space station must be capable of terminating transmissions by telecommand when directed by the FCC. (E1D06) A telecommand station in the amateur satellite service is an amateur station that transmits communications to initiate, modify or terminate functions of a space station. (E1D03)
An amateur station eligible to be a telecommand stations is any amateur station so designated by the space station licensee, subject to the privileges of the class of operator license held by the control operator. (E1D10) All classes of licensees are authorized to be the control operator of a space station. (E1D05)
Another important concept in the amateur satellite service is the Earth station. An Earth station in the amateur satellite service is an amateur station within 50 km of the Earth’s surface intended for communications with amateur stations by means of objects in space. (E1D04) Any amateur station, subject to the privileges of the class of operator license held by the control operator is eligible to operate as an Earth station. (E1D11)
To obtain information about the operation of the space station itself, many space stations send telemetry. Telemetry is defined as one-way transmission of measurements at a distance from the measuring instrument. (E1D01)
Working the satellites is a very popular amateur radio activity. There’s even an organization dedicated to launching and operating amateur radio satellites – AMSAT (www.amsat.org).
Perhaps the most important thing you need to know when trying to communicate via satellite is where the satellites are. One way to predict the location of a satellite at a given time is by calculations using the Keplerian elements for the specified satellite. (E2A12)
Amateur radio satellites are not in a geostationary orbit. That is to say they are constantly changing position in relationship to a point on the Earth. The type of satellite appears to stay in one position in the sky is geostationary.
When determining where a satellite is, you might want to know its orbital period. The orbital period of an Earth satellite is the time it takes for a satellite to complete one revolution around the Earth.(E2A03)
It’s also important to know the direction in which it is travelling. The direction of an ascending pass for an amateur satellite is from south to north. (E2A01) The direction of a descending pass for an amateur satellite is from north to south. (E2A02)
Next, you need to know what mode the satellite is in. The term mode as applied to an amateur radio satellite means the satellite’s uplink and downlink frequency bands. (E2A04)
We use a combination of letters to denote the mode. The letters in a satellite’s mode designator specify the uplink and downlink frequency ranges. (E2A05) If it were operating in mode U/V, a satellite’s receive signals would be in the 435-438 MHz band. (E2A06) U stands for UHF, V of VHF. With regard to satellite communications, the terms L band and S band specify the 23 centimeter and 13 centimeter bands. (E2A09)
Satellites repeat signals using transponders. Transponders are similar to repeaters, except that they receive signals across a band of frequencies and repeat them across another band of frequencies. The most common type of transponder is the linear transponder. All of these choices are correct when talking about the types of signals can be relayed through a linear transponder (E2A07):
One thing to keep in mind is to keep your transmitter power to the minimum needed to hit the satellite. Effective radiated power to a satellite which uses a linear transponder should be limited to avoid reducing the downlink power to all other users. (E2A08)
There are quite a few interesting phenomena that result from the fact that satellites rotate while they are orbiting. One reason the received signal from an amateur satellite may exhibit a rapidly repeating fading effect is because the satellite is spinning. (E2A10) To mitigate the effects of this of fading, you might use a circularly polarized antenna. A circularly polarized antenna is the type of antenna that can be used to minimize the effects of spin modulation and Faraday rotation. (E2A11)
Here are some cool things I found on the Net recently:
Radio tutorial – building your first station. This YouTube video tutorial by N7FTP gives some good advice on setting up your first ham shack.
Wi-Fi and the Bad Boys of Radio (review). I haven’t yet read this book, but this review certainly makes me want to do so. The book was written by Alex Hills, who played a part in the development of WiFi technology. Alex, AL7K, got his start in radio as a ham radio operator. From there, he went on to broadcast engineering, and then to a position with Carnegie Mellon University, where he worked on WiFi technology.
Radio hams pick up Mars rover Curiosity’s signals. This story describes how some German amateurs are working with NASA to receive telemetry from the Mars Science Laboratory spacecraft, which is heading towards Mars carrying a one-ton nuclear powered robot rover named Curiosity.
ARISSat-1, the satellite designed and built by amateur radio operators to specifically interest students in scientific and technological careers, is scheduled to be deployed from the International Space Station (ISS) this Wednesday August 3.
The extra-vehicular activity (EVA) is due to be broadcast on NASA TV, starting at 1430 UTC (Coordinated Universal Time) when the hatch of the ISS will open.
Here are three items that caught my eye in the last couple of days:
From Frank via the HamRadioHelpGroup mailing list:
Today in 1946, the United States Army Signal Corps at Fort Monmouth, New Jersey successfully conducted Project Diana, bouncing radio waves off the moon and receiving the reflected signals. 65 years later, ham radio operators all over the world conduct moon bounce or EME communications (Earth-Moon-Earth), with relatively inexpensive equipment.
This from Allen Pitts, W1AGP, ARRL Media & PR Manager, via the PR mailling list:
It was quite an exciting day for ARISS yesterday with the Expedition 18 crew docking and the start up of Richard Garriott’s ham radio activities. Here are some updates and plans for ARISS during Richard’s flight.
Richard, W5KWQ, fired up the radio and started SSTV operations just a couple of hours after docking. Richard planned to support a slide show mode using the SpaceCam software and the SSTV interface box at the beginning of his flight, which is what you saw yesterday. A number of the images were sent down using Martin 1, a higher quality but longer transmit SSTV mode. The Russian team, led by Sergey Samburov, RV3DR, had requested testing several high quality image modes during Richard’s flight, so don’t be surprised if you see Martin 1 or other high resolution SSTV modes during Richard’s flight. We have asked Richard to move to the default Robot 36 mode for the time being and to space out the images once every 3 minutes to reduce the radio transmit duty cycle. Richard confirmed that he will support this. He also has transitioned to the VC-H1 as this will allow Richard to use the computer to support his Earth ops and still support SSTV.
We have had a number of image uploads on the Gallery site by hams all around the world. The ARISS team appreciates your volunteer support through all the SSTV images that have been uploaded. A volunteer ARISS team is working 24/7 during Richard’s flight to review these images, to understand how the SSTV operations is progressing, and to include some of these images on the Gallery pages. ALL the images you have uploaded have been archived and are being reviewed. Please continue to upload these images as they help the ARISS team analyze and redirect the SSTV operations. You are welome to upload these to the gallery page.
We also have a blog available that provides the latest ARISS information for this expedition.
You can also reach these sites through the ARISS website.
Some other information:
- SSTV uplink/downlink: Richard is really not supporting SSTV uplinks during his short duration mission. The downlink is on the normal ARISS VHF downlink, 145.800.
- General Voice Contacts: Use the regular general voice frequencies. 145.80 downlink. Uplinks are 144.49 in Region 2 (Americas) and 145.20 for Region 1 (Europe, Africa, Middle East) and Region 3 (Australia, Asia). Richard and Mike Fincke, KE5AIT, have been on the air on voice since shortly after docking yesterday.
- Sleep Period Activity: We have asked the crew to turn packet on during sleep periods. Our intent is to keep SSTV active during their work day. The rationale for this is that we are having some issues with the software based (SpaceCam) SSTV system occasionally keeping the radio keyed down after an image transmission. And we have a limited set of Russian batteries available during Richard’s flight for the VC-H1.
You are witnessing and are a part of history: Some of you have asked why Richard is using his callsign for some QSOs and SSTV contacts instead of the ISS station callsigns. There is a long and proud history that is attached to the Garriotts. This includes ham radio in space and their personal callsigns. 25 years ago, Richard’s father, Owen Garriott, W5LFL, initiated the first ham radio contacts from space on the STS-9 SAREX mission. Richard, W5KWQ, is following in his father’s footsteps, using the ARISS ham radio system extensively on his first flight. And Richard’s callsign is actually his grandfather’s original callsign. So you can see that this mission touches 3 generations of ham radio and 2 generations of ham radio in space!
EE Times has just published a very cool article with some history on SuitSat 1 and some design info on SuitSat 2. Unfortunately, they don’t give a date for the launch of the second SuitSat. Here’s an excerpt from the article:
The experience proved so interesting that the engineers enthusiastically signed up for SuitSat-2. Leveraging their acquired knowledge, the team has already developed a new solar-conversion technique for the follow-on satellite that will extend system life to months instead of weeks. They have also crafted a software-defined, full-duplex radio with a better antenna for two-way communication and more-refined control.
For more information, go to the SuitSat website, which has links to a couple of ARRL articles on SuitSat 2.
I’m not big on working satellites, but this is kind of cool…..Dan
QST de W1AW
Space Bulletin 004 ARLS004
>From ARRL Headquarters
Newington, CT April 28, 2008
To all radio amateurs
SB SPACE ARL ARLS004
ARLS004 Ten New Satellites in Orbit
Ten satellites reached orbit April 28 aboard an Indian PSLV-C9
rocket launched from the Satish Dhawan Space Center. The primary
payloads were India’s CARTOSAT-2A and IMS-1 satellites. In addition
to the NLS-5 and RUBIN-8 satellites, the rocket carried six CubeSat
research satellites, all of which communicate using Amateur Radio
frequencies. All spacecraft deployed normally and appear to be
functional at this time.
The SEEDS satellite is designed and built by students at Japan’s
Nihon University. When fully operational, SEEDS will download
telemetry in Morse code and 1200-baud FM AFSK packet radio at
437.485 MHz. The satellite also has Slow-Scan TV (SSTV) capability.
Several stations have reported receiving SEEDS CW telemetry and the
team would appreciate receiving more reports from amateurs at their
ground station Web page.
AAUSAT-II is the creation of a student team at Aalborg University in
Denmark. It will downlink scientific telemetry at 437.425 MHz using
1200 or 9600-baud packet.
Can-X2 is a product of students at the University of Toronto
Institute for Aerospace Studies, Space Flight Laboratory
(UTIAS/SFL). Can-X2 will downlink telemetry at 437.478 MHz using 4
kbps GFSK, but the downlink will be active only when the satellite
is within range of the Toronto ground station.
Compass-One was designed and built by students at Aachen University
of Applied Sciences in Germany. The satellite features a Morse code
telemetry beacon at 437.275 MHz. Compass-1 will also provide a
packet radio data downlink, which will include image data, at
Cute 1.7 + APDII is a satellite created by students at the Tokyo
Institute of Technology. This satellite will not only provide
telemetry, it will also offer a 9600-baud packet store-and-forward
message relay with an uplink at 1267.6 MHz and a downlink at 437.475
Delfi-C3 was designed and built by students at Delft University of
Technology in the Netherlands. It includes an SSB/CW linear
transponder. The satellite will be in telemetry-only mode for the
first three months of the mission, after which it will be switched
to transponder mode. Delfi-C3 downlinks 1200-baud packet telemetry
at 145.870 MHz. The linear transponder, when activated, will have an
uplink passband from 435.530 to 435.570 MHz and a corresponding
downlink passband from 145.880 to 145.920 MHz.
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