Hi Domenico,
I could be wrong but I think your budget is correct for a regenerative
transponder but for a bent pipe transponder we need to add the uplink noise to
the downlink noise where
C/N (total) = 1/((1/C-Nup)+(1/C-Ndn)) which in this case would be about 6.7 dB.
Still pretty good
I agree, the ITAR rules are outrageous and have done more harm than good to the
U.S.. I received the following from a "Satellite Today" newsletter. It doesn't
specifically talk about ITAR but indicates there may be a glimmer of hope when
dealing with launches through ISRO...Howie AB2S
-
I agree with "the Bobs" and others that you have to play the cards you're
dealt and be part of the solution. Allot of people put many hours of time,
effort and their own money into AMSAT and I certainly thank them all.
I disagree that we should abandon the "HEO fetish" as it was put. At t
With all the recent discussion about launch costs, I thought this would be of
interest:
Details of New Japanese Cost-Cutting Launch Vehicle Leaked
August 27, 2009 | Satellite Today | Staff Writer
[Satellite TODAY 08-28-09] The Japan Aerospace Exploration Agency (JAXA) is
spending $213 million t
Some maritime TVRO antennas used a mechanical scan at the feed point. A motor
would either rotate an attenuator disk or offset the feed in a circular motion.
A resolver kept track of the feed location in relation to received signal
strength. The antenna was then slewed in the direction of best
I had several email exchanges with Zac earlier in the year when the call went
out for Amateur involvement. I was trying to get enough information to attempt
to put together a hardware decoder for the spread spectrum signal. The Cornell
team seemed only interested in having hams send in data
I agree with much of what Dan, N8GFV, says. Our best hope of a high altitude
satellite is probably a hosted payload on a GEO sat. To make that viable we
need to consider the entire mission. GEO satellite operators are a for-profit
business and every aspect of a commercial satellite has a dollar
Hi Jonas,
If you have something capable of generating 422.967 MHz you should be able to
easily use the third harmonic. Remember that the original frequency shift at
422 is also tripled, so reduce the shift on the original signal accordingly.
Howie
AB2S
Minor clarification, Loran-A was used from WW-2 until it was turned off in the
1980's I believe. The current system, Loran-C was in commercial use starting in
the late 70's. When Loran-C was used for returning to a previously stored
waypoint, it's accuracy was almost as good as current GPS and
I built a dual band VHF/UHF cheap yagi with 3 elements on VHF and 8 on UHF. I
cross drilled the 3/4" PVC pipe boom and mounted the elements at 90 degrees
from each other. I made the VHF elements removable so that I could easily
transport the antenna in the car. I saw no interaction between the
I may be missing something, but if I understand the following statement
correctly:
"The ChipSats will transmit for approximately 10ms every 1-2 seconds, but the
signal is going to be beneath the noise floor. Detecting the signal requires a
pseudorandom noise (PRN) code, which Cornell will hand
A similar report showed up recently on the Satellite Today report:
[Satellite TODAY 12-29-10] Turkey plans to send 3USAT, the nation’s first
homemade communications test satellite, into orbit in September, satellite
communications operatorTurksat announced Dec. 28.
The satellite, under devel
What if we tried using SSB on the uplink and FM on the downlink as an
experiment sometime. If the uplink passband was left a little wide, several
stations could still be intelligible at once, assuming they weren't on the
exact same frequency, not to mention a cw signal or two off to the edges.
I recently attended the HackerSPACE conference in Kentucky hosted by Prof. Bob
Twiggs. I too was a Cubesat non-believer but after attending the conference I
came away with a new perspective. Universities are not given "gift
certificates" for free launches, they must compete for them with their
This is a good reason to use APRS on Cubesat for telemetry. Imagine if even
half of the cubesats launched transmitted their telemetry as APRS packets and
simultaneously operated as APRS digipeaters. We could have a global
constellation of APRS repeaters feeding the terrestrial internet backhaul
USC has delivered their Aeneas 3U cubesat for launch preparations later this
year. Pretty amazing what they did with a 3U cubesat.
http://www.isi.edu/projects/serc/aeneas
HowieAB2S
___
Sent via AMSAT-BB@amsat.or
I read the description of the satellite a little more carefully this time and
noticed it is being built "on a standard NRO cubesat bus". Very interesting
that an organization like NRO is utilizing cubesats. This also probably means
they are not using amateur spectrum for this one.
Great analogy Bob,
This was another case where the businessmen at Lightsquared and the
"politicians" at the FCC agreed on a plan without talking to the engineers.
Lightsquared didn't do their homework and the FCC didn't do their job
initially. Lightsquared should have never even considered usi
I vote for Intelsat G-11 at 304.5 deg E. This is a Ku band only bird, however,
the semi-retired Intelsat 805, which is co-located with this sat has a global C
band beam with a downlink that extends into the amateur 9cm satellite band
(3400-3410 MHz). I often wondered if Intelsat would consider
ndtrack contest
I have also "wondered" if any of the older commercial surplus satellites can be
"reprogrammed" for our use. I realized that idea is no doubt an over
simplification. Today's speculation can be tomorrows reality.
73 Bob W7LRD
From: "Howie
ined in the following web page.
>
> http://www.satsig.net/vsat-equipment/tdma-explanation.htm
>
> In simple word the TDMA often called "switcher" operate as a citizen
> Telephone Central Station that is not on earth but on board of the
> satellite.
>
> 73"
Hi Dave,
The answer is yes, TDMA voice can and has been used on commercial satellites;
LEO,MEO and GEO for years. Commercial GEO satellites, for the most part, are
just high powered frequency translators. All the TDMA part is generated on the
ground. The complication is that all users will hav
The conclusion of the recent WRC conference left open issues concerning the
allocation of spectrum for pico and nano satellites. The requirement was
identified as serious and will be an agenda item at the next WRC. In my
opinion, this will put pressure on ham allocations from 5.8 GHz and down.
Can someone suggest a thread locking liquid that can be used in space and
possibly a source.
Thanks,Howie AB2S
___
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member?
Check out RF Micro Devices DKFC5072A development board. This is a mixer and
synthesizer that is programmable via a USB cable. It's rated up to 6 GHz and
could form the basis of a universal transverter, just add appropriate filters
and amps. I have used the older version up to 2.5 GHz and they w
My experience with pendulum elevation was the same as Greg's. The hysteresis
made it unworkable. No matter how much I increased the weight or pendulum
length I could not get acceptable results. I shelved the project for the time
being.
- Howie AB2S
___
Hi Samudra,
Phased array is a generic term. Stacked yagi's are a phased array :) If you
mean electrically steered phased arrays, that's another story. If you mean
non-steered phase arrays, that is also another story. As far as I know there
has not been much work in the amateur community on el
While there may be good reason not to have a 2G/3G/4G phone transmitting from
orbit, I'm not so sure the same problems would apply to an Iridium transceiver.
Iridium is a global system with dedicated worldwide spectrum. There are no
terrestrial "cell sites" to interfere with. The Iridium system
As far as I know there are no transponders on any of the qubesats being
lauched. These are femtosats measuring 50cm (2 in) on a side and weighing less
than 200 grams. The link budget is quite challenging with the available power
budget. A transponder on this platform would need to be more power
Most commercial uplinks/downlinks are some form of synchronous data using some
form of PSK modulation (BPSK , QPSK, 8PSK etc.) . The approximate data clock
rate is known by the receiver. The receiver extracts clock information from the
transmitted data stream to synchronize the receivers local c
Thanks for that explanation Bob. The members of the Eagle-2 ($50sat) team were
having this discussion last night and none of us knew the answer. Now we do !
We were trying to determine when using the UNISAT-5 keps would no longer be
valid for $50sat.
- Howie AB2S
The $50sat team is asking for help form our friends in the southern hemisphere
in capturing telemetry form $50sat. We are trying to determine the charging
characteristics of the power system. The three team members all live above 40
degrees north and the satellite does not warm up enough during
Thanks Trevor,
Hope their data format includes a lng preamble to help acquire data. The
doppler is going to horrific..
Howie AB2S
___
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
N
Bob,
I don't have any experience using DTMF on HF but back in the day before satcom,
commercial marine HF SSB coast stations used a dual tone selective calling
system made by Lorain Electronics. The encoder used 11 tones, one each for the
digits 0-9 and a carrier tone. Each digit was transmitte
Just in case anyone was curious about the practicality of actually transmitting
WiFi from a cubesat, I did a quick link budget. Based on typical 802.11 specs,
the MDS of a receiver is about -90 dBm. The path loss at 2.4GHz between a
ground station and a satellite overhead in a 600Km orbit is a l
The $50sat team is celebrating 90 days in orbit by proposing a technical
challenge to all interested amateurs. $50sat is capable of responding to uplink
command packets:
There are 3 open packets: Test packet - $50SAT responds by sending the RSSI of
the received packet in slow FM Morse. Req
details on the
uplinking. Is it 20Version20V1_1.pdf 73
Nitin [VU3TYG]
From: Howie DeFelice
To: "amsat-bb@amsat.org"
Sent: Friday, 21 February 2014 10:50 AM
Subject: [amsat-bb] $50sat
The $50sat team is celebrating 90 days in orbit by proposing a technical
challe
Is CDMA an authorized emission type for the Amateur service? What is the
chipping rate/bandwidth of these? Don't the PRN sequences need to be made
public so as not to be classified as "encryption" ? Detailed specs on the
Sprites is in short supply. Has anyone done a link budget, seems like allot
owied...@hotmail.com
CC: amsat-bb@amsat.org
70 CM is not just for the ham bands, it is a shared band check the ruleswa4hfn
Damon
On Tue, Mar 4, 2014 at 2:30 PM, Howie DeFelice wrote:
Is CDMA an authorized emission type for the Amateur service? What is the
chipping rate/bandwidth of these? Don'
as well. I was trying to standardize the parameters (for QB50), so
the IARU could be handing out orthogonal codes to satellite teams, so avoid
clashes. But welcome to politics.
Wouter PA3WEG
On Tue, Mar 4, 2014 at 10:16 PM, Howie DeFelice wrote:
Yes, that is true, so are these license
"Keep in mind that the downlink is not effected by usa rules"
This may be true if the owner of the satellite is not licensed in
the USA or it is operating on some service other than the Amateur Radio
Service. ITU recommends policy, it doesn't make or enforce law as I
understand it.
Before
I am glad that the FCC considered this and granted the experimental license.
You can simulate for all eternity but nothing replaces a real world test. By
obtaining an FCC experimental license, the application with initial descriptive
details become public record. The licensee then has the option
Hi Tony,
I'm not up to speed on the current Inmarsat Aero service, but they are most
likely using thee 4th generation satellite constellation which has numerous
small overlapping spotbeams. They also have larger area beams as well as a
global beam. There are several different aero services provi
INMARSAT has several services for airliners. The Aero-H and Aero-H+ services
both accomodate ACARS and other voicec and data services for airline operation.
Aero-H service operates on the INMARSAT I-3 constellation that has global and
regional beams. Aero-H+ can operate on either I-3 or I-4 sate
While it is true that MO-76 does not have a transponder, the satellite WILL
send you a signal report if you send it a correctly formatted data packet. To
do this requires some technical ability. The satellite uses an RFM-22
transceiver and receives FSK, not AFSK, data signals. The packet must be
e. Some folks might gripe
> because it doesn't have a transponder but they would be missing the
> the big picture. Without innovation, the ham satellite community will
> waste away into obscurity.
>
> Who knows? Maybe we will have a $50HEOSATwithTRANSPONDER
> someday
All Inmarsat satellites though the F-3 series have been in inclined orbits
since beginning of life. This gives them extended on orbit lifetime. The
beamwidth of the Inmarsat L band ground terminals is large enough that tracking
isn't required. The gateway stations operate at C band with large an
I idid some checking on www.satellite-calculations.com and was surprised at
what I found.
SAT LOCATION INCLINATION
3-F1 64E 1.67 deg
3-F2 15W 0.21 deg
3-F3 178E 1.07 deg
3-F4 54W 3.6 d
"I bet (a small bet anyway) my cell phone carrier doesn't save receive
frequency data accurate enough to determine what direction I am driving
though."
You are probably right since the doppler shift is pretty small ( at least I
hope it is :) ) on a
cellphone. The satellite access is MA-TDMA so th
If you are phasing the two antennas to get 3db of gain with the same
polarization, then the two cables can be any length as long as they are exactly
the same electrical length. It's a good practice to make two cables from the
same batch of coax if possible.
- Howie
A new message has been added to the $50sat CW rotation in memory of Tony AA2TX;
"73 AA2TX"
- Howie AB2S
___
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to
The MO-76 $50sat team is pleased to announce that $50sat was chosen as Project
of the Month by Rev-Ed, the makers of the PICAXE processor used in MO-76.
http://www.picaxe.com/Project-Gallery/50SAT/
Howie AB2S
> The Fermi Paradox asks, if there are other intelligent civilizations in the
> galaxy, why have they not come to visit us?
...They must have intercepted satellite transmissions of C-SPAN and concluded
there is no intelligent life on earth.
- Howie AB2S
"... and read it literally. The wording is such that an English major would see
it as
describing an incomplete, not-thoroughly tested project was being discussed."
Good thing there are more engineering majors than English majors on the list :)
- Howie AB2S
At the Satellite2014 conference in Washington D.C. this year I floated an idea
past a couple of the major GEO satellite operators for a hosted payload that
consisted of a 1.2 GHz receiver package that used the low end of an existing C
band global beam transponder (3.4 GHz.) as the downlink. I di
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