New Satellite Downlink?
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz). (presently coming over in the mid afternoon). My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone has to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations. These satellites of course were the original Navy Navigation satellite system (also called OSCARS) and so the message would be in-place of the normal navigation data. SO in a sense, this is a downlink BROADCAST application. Since ham radio is two way, I'm stumped for applications.
The total message capability of 500 Bytes can contain one long ARRL bulletin, or 20 APRS position/status reports, or say 20 or so APRS text messages, or say 50 "callsign exchanges" or maybe even 1 thumbnail image... but what's the application?
Even if we allow say, INTERNET link to the command station for "anyone" to contribute to the twice per-day upload, then everyone's receiver application can receive them... For what?
So Im looking for ideas. All I can come up with so far is: 1) ARRL Bulletins? (I don't even know how often ARRL sends bulletins...) 2) Navy/Army/AF MARS broadcast bulletins... 3) Internet message in-to-command-upload-to message RF downlink. Two stations do this to each other and it counts as a two-way QSO? 4) ...
Every scenario of interest usually begins with the much higher value of UPLINK from the individual field station, not downlink.. Hence I am stumped.
HUMMH... Maybe purely educational? If the software can run on any PC with a sound card connected to any scanner... Then every school can use it as a satellite downlink signal of interest.. What kind of thumbnail image can fit in 500 bytes? Send in your picture and get it downlinked on a given day?
Etc..
Will need a DSP volunteer to write the sound card decoder.
Bob, WB4APR
On Wed, 2010-08-25 at 12:27 -0400, Robert Bruninga wrote:
HUMMH... Maybe purely educational?
Sending ebooks, a few words at a time?
Will need a DSP volunteer to write the sound card decoder.
I'll bite. Is it currently transmitting? Are there "known good" recordings of its data?
What would I be looking for, to get the correct pass predictions?
Gordon MM0YEQ
On Wednesday 25 August 2010 12:27:00 Robert Bruninga wrote:
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz). (presently coming over in the mid afternoon). My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone has to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations. These satellites of course were the original Navy Navigation satellite system (also called OSCARS) and so the message would be in-place of the normal navigation data. SO in a sense, this is a downlink BROADCAST application. Since ham radio is two way, I'm stumped for applications.
Well, I'm not sure how many applications there are for this, but it could be fun to try some stuff.
Way way back hundreds of years ago in the 70's I wrote some code to take English text and crunch it down and transmit it over a modem.
I won't say the following is reasonable, but at 50 baud the little link needs all the help it can get. ;-)
A lookup table can be made for about 65,000 of the most commonly used words plus various technical stuff. A message can then it converted into a series of 16-bit offsets into the table of words, taking 2 bytes (octets) per word. Printing out words takes the stream of data, does a lookup for each 16-bit quantity, prints that word plus a space, and goes on.
A word like "communications" which is 14 bytes becomes two and is thus a win, but "a" "I" and the like is a loss. There could be an escape sequence to provide for the literal transmission of a word not in the 65,000 lookup table, and one could also be added for upper casing of the next word, etc.
Doing this, you can transmit 250 words from the lookup table each minute, fairly faster than squirting out raw ASCII.
Since you'd likely need a decoder no matter what the transmission is, the 65,000 word table is stored on the client side. Hilarity will probably ensue when someone doesn't update their table after a big change, and gets slightly demented messages till they update their code.
Thinking about what to transmit... Possibly space weather transmissions? CMEs and such are something that has world wide impact.
Well, that, or national lottery scores.
Hi Steve,
I wonder how that would work with multiple languages:)
73
Graham G3VZV ----- Original Message ----- From: "STeve Andre'" [email protected] To: [email protected] Sent: Wednesday, August 25, 2010 10:24 PM Subject: [amsat-bb] Re: New Satellite Downlink?
On Wednesday 25 August 2010 12:27:00 Robert Bruninga wrote:
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz). (presently coming over in the mid afternoon). My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone has to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations. These satellites of course were the original Navy Navigation satellite system (also called OSCARS) and so the message would be in-place of the normal navigation data. SO in a sense, this is a downlink BROADCAST application. Since ham radio is two way, I'm stumped for applications.
Well, I'm not sure how many applications there are for this, but it could be fun to try some stuff.
Way way back hundreds of years ago in the 70's I wrote some code to take English text and crunch it down and transmit it over a modem.
I won't say the following is reasonable, but at 50 baud the little link needs all the help it can get. ;-)
A lookup table can be made for about 65,000 of the most commonly used words plus various technical stuff. A message can then it converted into a series of 16-bit offsets into the table of words, taking 2 bytes (octets) per word. Printing out words takes the stream of data, does a lookup for each 16-bit quantity, prints that word plus a space, and goes on.
A word like "communications" which is 14 bytes becomes two and is thus a win, but "a" "I" and the like is a loss. There could be an escape sequence to provide for the literal transmission of a word not in the 65,000 lookup table, and one could also be added for upper casing of the next word, etc.
Doing this, you can transmit 250 words from the lookup table each minute, fairly faster than squirting out raw ASCII.
Since you'd likely need a decoder no matter what the transmission is, the 65,000 word table is stored on the client side. Hilarity will probably ensue when someone doesn't update their table after a big change, and gets slightly demented messages till they update their code.
Thinking about what to transmit... Possibly space weather transmissions? CMEs and such are something that has world wide impact.
Well, that, or national lottery scores.
-- STeve Andre' wb8wsf en82 Disease Control Warden Dept. of Political Science Michigan State University
A day without Windows is like a day without a nuclear incident. _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Heh. One of the escape sequences could be which language to use, so with the 16-bit scheme here, you could have 64K possible ones to choose from. Just have a 65,000 word table for each one.
You'd send out messages one language at a time.
On Wednesday 25 August 2010 17:55:09 Graham Shirville wrote:
Hi Steve,
I wonder how that would work with multiple languages:)
73
Graham G3VZV ----- Original Message ----- From: "STeve Andre'" [email protected] To: [email protected] Sent: Wednesday, August 25, 2010 10:24 PM Subject: [amsat-bb] Re: New Satellite Downlink?
On Wednesday 25 August 2010 12:27:00 Robert Bruninga wrote:
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz). (presently coming over in the mid afternoon). My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone has to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations. These satellites of course were the original Navy Navigation satellite system (also called OSCARS) and so the message would be in-place of the normal navigation data. SO in a sense, this is a downlink BROADCAST application. Since ham radio is two way, I'm stumped for applications.
Well, I'm not sure how many applications there are for this, but it could be fun to try some stuff.
Way way back hundreds of years ago in the 70's I wrote some code to take English text and crunch it down and transmit it over a modem.
I won't say the following is reasonable, but at 50 baud the little link needs all the help it can get. ;-)
A lookup table can be made for about 65,000 of the most commonly used words plus various technical stuff. A message can then it converted into a series of 16-bit offsets into the table of words, taking 2 bytes (octets) per word. Printing out words takes the stream of data, does a lookup for each 16-bit quantity, prints that word plus a space, and goes on.
A word like "communications" which is 14 bytes becomes two and is thus a win, but "a" "I" and the like is a loss. There could be an escape sequence to provide for the literal transmission of a word not in the 65,000 lookup table, and one could also be added for upper casing of the next word, etc.
Doing this, you can transmit 250 words from the lookup table each minute, fairly faster than squirting out raw ASCII.
Since you'd likely need a decoder no matter what the transmission is, the 65,000 word table is stored on the client side. Hilarity will probably ensue when someone doesn't update their table after a big change, and gets slightly demented messages till they update their code.
Thinking about what to transmit... Possibly space weather transmissions? CMEs and such are something that has world wide impact.
Well, that, or national lottery scores.
-- STeve Andre' wb8wsf en82 Disease Control Warden Dept. of Political Science Michigan State University
A day without Windows is like a day without a nuclear incident. _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Assuming TRANSIT uses an 8-bit byte, then it has the capability of sending 4,000 different messages (one for each bit). Probably would want some checksum, so the total different messages would be less.
Hmmmm, with 3000+ message choices, there might be some good use.
Regional weather warnings? Status of 3000 different "stations"?
I actually had a TRANSIT receiver several years ago. It would still lock onto the satellites, but the navigation information is no longer valid. Bob is right: all it took was simple vertical to receive it.
For folks that don't know, TRANSIT was the one of the first satellite navigation system. It was a GPS of sorts.
I've done DSP soundcard coding before. Years ago I wrote a DGPS decoder, so if you need some more coders, I'd be happy to help.
Jon K7PGB
On Wed, 25 Aug 2010, Robert Bruninga wrote:
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz). (presently coming over in the mid afternoon). My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone has to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations. These satellites of course were the original Navy Navigation satellite system (also called OSCARS) and so the message would be in-place of the normal navigation data. SO in a sense, this is a downlink BROADCAST application. Since ham radio is two way, I'm stumped for applications.
The total message capability of 500 Bytes can contain one long ARRL bulletin, or 20 APRS position/status reports, or say 20 or so APRS text messages, or say 50 "callsign exchanges" or maybe even 1 thumbnail image... but what's the application?
Even if we allow say, INTERNET link to the command station for "anyone" to contribute to the twice per-day upload, then everyone's receiver application can receive them... For what?
So Im looking for ideas. All I can come up with so far is:
- ARRL Bulletins? (I don't even know how often ARRL sends
bulletins...) 2) Navy/Army/AF MARS broadcast bulletins... 3) Internet message in-to-command-upload-to message RF downlink. Two stations do this to each other and it counts as a two-way QSO? 4) ...
Every scenario of interest usually begins with the much higher value of UPLINK from the individual field station, not downlink.. Hence I am stumped.
HUMMH... Maybe purely educational? If the software can run on any PC with a sound card connected to any scanner... Then every school can use it as a satellite downlink signal of interest.. What kind of thumbnail image can fit in 500 bytes? Send in your picture and get it downlinked on a given day?
Etc..
Will need a DSP volunteer to write the sound card decoder.
Bob, WB4APR
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I've done DSP soundcard coding before. Years ago I wrote a DGPS decoder, so if you need some more coders, I'd be happy to help.
I'm embarassed that I still have not heard the bird on 2 tries. Its supposed to be on 149.987 MHz and you can hear it's 2.3 KHz tone with an FM receiver... I did hear it on APL-JHU's system also consisting of an amateur OSCAR class station... But not on mine yet.... OOPS! Wait! I have a very sharp DCI BANDPASS filter up there! Duh.... Ill try a different antenna this time!
OK, the signal is 50 baud modulated with + and - 60 degree phase shift on the 400 MHz carrier (it can be switched to the 149.987 MHz carrier, but is not there currently). The wave form of the modulation is as follows:
To transmit a "1" the carrier is phase shifted +60 degrees for about 2 ms, then shifted -60 deg for about 2 ms and then brought back to carrier with no phase shift for about 6 ms, then it is shifted - 60 deg again for 2ms and then +60 for 2ms and then brought back to no shift for another 6 ms. The "0" is the opposite pattern of shifts. This process provides a clock signal at twice the bit rate. The actual exact period of each symbol is 19.7 ms.
The beginning of each exact 2 minute (6103 bit block) is marked with 0111111111111111111111110, that is 23 "1"'s with a leading and ttrailing zero.
Bob, Wb4APR
On Wed, 25 Aug 2010, Robert Bruninga wrote:
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites
with
a 50 baud downlink at 149.985 (and 400 MHz). (presently
coming
over in the mid afternoon). My problem is, coming up with
any
meaningful application to use them for communications that
would
capture the interest of students, hams or volunteers in
support
of education, public service or emergency comms or just
plain
fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone
has
to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is
very
specialized and can ONLY BE DONE from one (or two) very
special
commmand stations. These satellites of course were the
original
Navy Navigation satellite system (also called OSCARS) and so
the
message would be in-place of the normal navigation data. SO
in
a sense, this is a downlink BROADCAST application. Since
ham
radio is two way, I'm stumped for applications.
The total message capability of 500 Bytes can contain one
long
ARRL bulletin, or 20 APRS position/status reports, or say 20
or
so APRS text messages, or say 50 "callsign exchanges" or
maybe
even 1 thumbnail image... but what's the application?
Even if we allow say, INTERNET link to the command station
for
"anyone" to contribute to the twice per-day upload, then everyone's receiver application can receive them... For
what?
So Im looking for ideas. All I can come up with so far is:
- ARRL Bulletins? (I don't even know how often ARRL sends
bulletins...) 2) Navy/Army/AF MARS broadcast bulletins... 3) Internet message in-to-command-upload-to message RF
downlink.
Two stations do this to each other and it counts as a
two-way
QSO? 4) ...
Every scenario of interest usually begins with the much
higher
value of UPLINK from the individual field station, not downlink.. Hence I am stumped.
HUMMH... Maybe purely educational? If the software can run
on
any PC with a sound card connected to any scanner... Then
every
school can use it as a satellite downlink signal of
interest..
What kind of thumbnail image can fit in 500 bytes? Send in
your
picture and get it downlinked on a given day?
Etc..
Will need a DSP volunteer to write the sound card decoder.
Bob, WB4APR
Sent via [email protected]. Opinions expressed are those
of the author.
Not an AMSAT-NA member? Join now to support the amateur
satellite program!
Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
OK, I think I have an application idea that would apply to emergency comunications response.
Since this is a mostly one-way downlink satellite channel (that can be received with ANY FM receiver a vertical whip and a laptop with sound card), this means it can be fielded in the emergency area very trivially. The use of this channel would be to ACKnowledge the receipt of outgoing health and welfare traffic. I would propose that the MARS volunteers could manage this during an emergency.
Currently traffic from an emergency is usually one-way outbound, and all inboud health-and-welfare concern traffic is blocked to keep the channels open. But if this satellite broadcast channel was available, then outboud traffic could assign a code number to each outbond message and when that was delivered to the final recepient, then the code number coiuld be sent back over the satellite broadcast channel to confirm delivery. In addition, a few digits could also be appended to indicate typical responses from a pre-set response list.
So, for normal non-emergency times, the channel would be for Q-tweets to exercise the system. During emergencys, the downlink could be switched over to this emergency ack system.
Bob, WB4APR
-----Original Message----- OOPS! Wait! I have a very sharp DCI BANDPASS filter up there! Duh.... Ill try a different antenna this time!
Yep, heard it fine on an HT with a long whip.
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz).... My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations.
Which two Transit series satellites did you say it might be? There seems a choice of several.
On 25-Aug-10 16:27, Robert Bruninga wrote:
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites
Which two Transit series satellites did you say it might be? There seems a choice of several.
The only two that are working I think. #23 and #25. They are object numbers. 19070 and 19419
That's OSCAR 23 and OSCAR 25. Arn't they both Korean sats?
On 25-Aug-10 21:54, Robert Bruninga wrote:
Which two Transit series satellites did you say it might be? There seems a choice of several.
The only two that are working I think. #23 and #25. They are object numbers. 19070 and 19419
No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3092 - Release Date: 08/24/10 15:31:00
OK. The complete catalogue has 2 of each OSCAR 23 and OSCAR 25. I need the ones with the 90dgf inclination.
On 25-Aug-10 22:11, Nigel Gunn G8IFF/W8IFF wrote:
That's OSCAR 23 and OSCAR 25. Arn't they both Korean sats?
With increasing solar activity and "new" awareness of the possible detrimental effects worldwide of solar storms, combined with the time delay for a solar event to reach Earth (2-3 days) I believe that a possible rebroadcast of "Solar Weather" ala WWV style, could be a useful educational tool as well as a "timely" prognostication for radio operations around the world.
It would also serve as a "town crier" type service, warning people worldwide of a potential disruptive event.
The standardized resource could be WWV or any other agency willing to provide the info on a daily basis.
Solar storm activity reports would not depend on internet access or shortwave receivers but a common scanner and any computer.
The mission could be re-tasked after the sunspot peak is well passed.
Well...just my first thought... there may be others...
Roger WA1KAT
Robert Bruninga wrote:
Which two Transit series satellites did you say it might be? There seems a choice of several.
The only two that are working I think. #23 and #25. They are object numbers. 19070 and 19419
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Transits #23 and #25. object nos 19070 and 19419.
Here is a possible application based on the unique nature of the "navigation" message which is 26 lines of 6 words with each being 39 bits. But the first 8 lines are changed every 2 minutes by inserting a new line and scrolling off the oldest one. We can use this for a list of callsigns.
We can get a callsign and extra 8 bit authorization ID into the 39 bits, or 6 calls per line for a total of 48 calls. Then the remaining 18 lines are available for what I call Quarter-Tweet messages of 35 bytes each. We will also reserve a few lines for special bulletins.
So here is how it would work.
1) User initiates a login request via internet to the command station. 2) His call is added to the Login list on the satellite plus an authorization byte 3) As noted above, this list scrolls down and only the last 48 are visible 4) Next he has to tune in the downlink to see his authorization byte. 5) Now with his authorization byte, he can send a Q-tweet via the internet 6) Which now shows up with 18 other Q-tweets in the remaining 18 lines downlink
Your Qtweet can contain a call to another station and when he responds, you can count a QSO.
Something like that. The above idea lets everyone play, but requires that they can hear the satllite first (like any other satelite) before then can send an uplink (via the internet) for reception (downlink) via RF.
We will use a 5 bit code (like RTTY) but will replace the CR and LF with the "." and a CAPS shift. SO the 31 possible characters are a-z plus "." plus CAPS, FIGS and LTRS. This allows normal mixed case text...
Bob, WB4APR
Here is more info on how we could use the Navigation message of these old satellites for a rudimentary satellite Q-Tweet system. That is, you can send "Quarter-Tweets" for inclusion in the downlink... But only after you have scheduled a login and obtained (in the next downlink) your authorization code... See the drawing: http://aprs.org/transit/call-encoding.GIF
Using the scenario below: Bob, Wb4APR
-----Original Message----- On Behalf Of Robert Bruninga Sent: Thursday, August 26, 2010 8:39 AM Subject: [amsat-bb] Re: New Satellite Downlink?
Transits #23 and #25. object nos 19070 and 19419.
Here is a possible application based on the unique nature of the "navigation" message which is 26 lines of 6 words with each being 39 bits. But one word in each of the first 8 lines are changed every 2 minutes by inserting a new word and scrolling off the oldest one. We can use this for a list of callsigns.
We can get a callsign and extra 8 bit authorization ID into each of the 39 bit words. Then the rest of thos first 6 lines can be older callsigns and then the remaining 18 lines are available for what I call Quarter-Tweet messages of 35 bytes each. We will also reserve a few lines for special bulletins.
So here is how it would work.
- User initiates a login request via internet to
the command station.
- His call is added to the Login list on the
satellite plus an authorization byte
- As noted above, this list scrolls down and only
the last 48 are visible
- Next he has to tune in the downlink to see his
authorization byte.
- Now with his authorization byte, he can send a
Q-tweet via the internet.
- Which now shows up with 18 other Q-tweets in
the remaining 18 lines downlink
Your Qtweet can contain a call to another station and when he responds, you can count a QSO.
Something like that. The above idea lets everyone play, but requires that they can hear the satllite first (like any other satelite) before then can send an uplink (via the internet)
for
reception (downlink) via RF.
We will use a 5 bit code (like RTTY) but will replace the CR
and
LF with the "." and a CAPS shift. SO the 31 possible
characters
are a-z plus "." plus CAPS, FIGS and LTRS. This allows normal mixed case text...
Bob, WB4APR
Question: since there is no amateur radio allocation at 149.985, "we" (hams) would be asking the Navy, to whom the downlink frequency is allocated, to transmit one-way amateur communications thru this satellite, correct?
Doesn't anyone else see potential legal problems involved here?
George, KA3HSW
----- Original Message ----- From: "Robert Bruninga" [email protected] To: [email protected] Sent: Wednesday, August 25, 2010 11:27 AM Subject: [amsat-bb] New Satellite Downlink?
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz). (presently coming over in the mid afternoon). My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone has to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations. These satellites of course were the original Navy Navigation satellite system (also called OSCARS) and so the message would be in-place of the normal navigation data. SO in a sense, this is a downlink BROADCAST application. Since ham radio is two way, I'm stumped for applications.
The total message capability of 500 Bytes can contain one long ARRL bulletin, or 20 APRS position/status reports, or say 20 or so APRS text messages, or say 50 "callsign exchanges" or maybe even 1 thumbnail image... but what's the application?
Even if we allow say, INTERNET link to the command station for "anyone" to contribute to the twice per-day upload, then everyone's receiver application can receive them... For what?
So Im looking for ideas. All I can come up with so far is:
- ARRL Bulletins? (I don't even know how often ARRL sends
bulletins...) 2) Navy/Army/AF MARS broadcast bulletins... 3) Internet message in-to-command-upload-to message RF downlink. Two stations do this to each other and it counts as a two-way QSO? 4) ...
Every scenario of interest usually begins with the much higher value of UPLINK from the individual field station, not downlink.. Hence I am stumped.
HUMMH... Maybe purely educational? If the software can run on any PC with a sound card connected to any scanner... Then every school can use it as a satellite downlink signal of interest.. What kind of thumbnail image can fit in 500 bytes? Send in your picture and get it downlinked on a given day?
Etc..
Will need a DSP volunteer to write the sound card decoder.
Bob, WB4APR
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Correct.
There will be legal problems in Europe as citizens (and amateurs) are not allowed to listen on frequencies that are not authorised in their countries.
On 27-Aug-10 23:28, George Henry wrote:
Question: since there is no amateur radio allocation at 149.985, "we" (hams) would be asking the Navy, to whom the downlink frequency is allocated, to transmit one-way amateur communications thru this satellite, correct?
Doesn't anyone else see potential legal problems involved here?
On Fri, 2010-08-27 at 23:40 +0000, Nigel Gunn G8IFF/W8IFF wrote:
Correct.
There will be legal problems in Europe as citizens (and amateurs) are not allowed to listen on frequencies that are not authorised in their countries.
I don't know where you've been in Europe, but that would be perfectly legal in the UK.
Gordon MM0YEQ
I would have to side with Nigel here as my understanding is that he is quite correct - you are not allowed to listen into the Police frequencies for instance or any other frequency that you are not authorized for - maybe you can in Scotland Gordon :-P
As always, I am happy to be corrected though.
David M0ZLB/KG4ZLB
On 8/28/2010 14:45, Gordon JC Pearce wrote:
On Fri, 2010-08-27 at 23:40 +0000, Nigel Gunn G8IFF/W8IFF wrote: I don't know where you've been in Europe, but that would be perfectly legal in the UK.
Gordon MM0YEQ
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At 08:00 AM 8/29/2010, David - KG4ZLB wrote:
I would have to side with Nigel here as my understanding is that he is quite correct - you are not allowed to listen into the Police frequencies for instance or any other frequency that you are not authorized for - maybe you can in Scotland Gordon :-P
Each country has its own rules. In Australia, you're allowed to listen to anything sent in the clear, except for traffic covered by the Telecommunications Act (i.e. phone calls). The Police were fair game, until they switched to encrypted digital systems several years ago.
73 de VK3JED / VK3IRL http://vkradio.com
In the USA
I am not aware of any Federal law that prevents listening to government frequencies. They are considered directed communications and can not be used for personal gain nor be repeated or transcribed by the listener.
There are many local laws, however as soon as the constitutionality of the local laws are challenged (Regulatory rights for radio communication are reserved for the Federal Government) charges are dropped. These laws are maintained only for their nuisance value.
Art, KC6UQH
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of David - KG4ZLB Sent: Saturday, August 28, 2010 3:01 PM Cc: [email protected] Subject: [amsat-bb] Re: New Satellite Downlink?
I would have to side with Nigel here as my understanding is that he is quite correct - you are not allowed to listen into the Police frequencies for instance or any other frequency that you are not authorized for - maybe you can in Scotland Gordon :-P
As always, I am happy to be corrected though.
David M0ZLB/KG4ZLB
On 8/28/2010 14:45, Gordon JC Pearce wrote:
On Fri, 2010-08-27 at 23:40 +0000, Nigel Gunn G8IFF/W8IFF wrote: I don't know where you've been in Europe, but that would be perfectly legal in the UK.
Gordon MM0YEQ
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Absolutely!
73 de W4AS
On Aug 27, 2010, at 7:28 PM, George Henry wrote:
Question: since there is no amateur radio allocation at 149.985, "we" (hams) would be asking the Navy, to whom the downlink frequency is allocated, to transmit one-way amateur communications thru this satellite, correct?
Doesn't anyone else see potential legal problems involved here?
George, KA3HSW
In my oppinion, I don't see much difference between the military broadcasting on
this satellite to hams and cross band HF contacts with military stations where the military transmits on their own frequencies knowing that hams are listening.
Granted in some places it may not be legal to listen to 149.985 or for hams to listen to non amateur broacasts but that is another issue.
If only the military can uplink to this satellite then I would expect that they are accountable for what gets broadcast.
----- Original Message ---- From: George Henry [email protected] To: amsat bb [email protected] Sent: Fri, August 27, 2010 4:28:02 PM Subject: [amsat-bb] Re: New Satellite Downlink?
Question: since there is no amateur radio allocation at 149.985, "we" (hams) would be asking the Navy, to whom the downlink frequency is allocated, to transmit one-way amateur communications thru this satellite, correct?
Doesn't anyone else see potential legal problems involved here?
George, KA3HSW
----- Original Message ----- From: "Robert Bruninga" [email protected] To: [email protected] Sent: Wednesday, August 25, 2010 11:27 AM Subject: [amsat-bb] New Satellite Downlink?
Possible new AMSAT Application?
We may have access to two old TRANSIT navigation satellites with a 50 baud downlink at 149.985 (and 400 MHz). (presently coming over in the mid afternoon). My problem is, coming up with any meaningful application to use them for communications that would capture the interest of students, hams or volunteers in support of education, public service or emergency comms or just plain fun...
The downlink can be heard on an OMNI antenna (though I would suggest a 3/4 wave (55") vertical) and could be decoded by a simple software only application with a sound card. (someone has to write it)...
The total useful message capability is about 500 bytes transmitted every 2 minutes (at 50 baud). The uplink is very specialized and can ONLY BE DONE from one (or two) very special commmand stations. These satellites of course were the original Navy Navigation satellite system (also called OSCARS) and so the message would be in-place of the normal navigation data. SO in a sense, this is a downlink BROADCAST application. Since ham radio is two way, I'm stumped for applications.
The total message capability of 500 Bytes can contain one long ARRL bulletin, or 20 APRS position/status reports, or say 20 or so APRS text messages, or say 50 "callsign exchanges" or maybe even 1 thumbnail image... but what's the application?
Even if we allow say, INTERNET link to the command station for "anyone" to contribute to the twice per-day upload, then everyone's receiver application can receive them... For what?
So Im looking for ideas. All I can come up with so far is:
- ARRL Bulletins? (I don't even know how often ARRL sends
bulletins...) 2) Navy/Army/AF MARS broadcast bulletins... 3) Internet message in-to-command-upload-to message RF downlink. Two stations do this to each other and it counts as a two-way QSO? 4) ...
Every scenario of interest usually begins with the much higher value of UPLINK from the individual field station, not downlink.. Hence I am stumped.
HUMMH... Maybe purely educational? If the software can run on any PC with a sound card connected to any scanner... Then every school can use it as a satellite downlink signal of interest.. What kind of thumbnail image can fit in 500 bytes? Send in your picture and get it downlinked on a given day?
Etc..
Will need a DSP volunteer to write the sound card decoder.
Bob, WB4APR
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participants (13)
-
Art McBride -
David - KG4ZLB -
George Henry -
Gordon JC Pearce -
Graham Shirville -
jon -
Mark Spencer -
Nigel Gunn G8IFF/W8IFF -
Robert Bruninga -
Roger Kolakowski -
Sebastian -
STeve Andre' -
Tony Langdon