Les,
Of course P4 is not even on the drawing board, but P4 will be very similar to Eagle as I read from Rick and Bob. So that means: mode-UV (maybe) - Linear analog tranponder. mode-US or LS - Linear analog transponder mode-SC or CX - Digital Voice/Video/Data SDX as main radio.
Will that mean channeled operation? I suppose for EMCOMM that would be best (hopefully, multi-channel). Will it be trunked? Or will it resemble packet UI or APRS? Because of the digital coding this does mean buying a ground unit designed by the P4 engineering team. Whether it will be built by AMSAT or the design licensed to private commercial mfrs, I do not know. Perhaps it can be made as a (partial) kit.
I think it is easy to get confused between what will the EMCOMM ground station look like and what the "apartment" ham station look like for the digital mode (remember that is voice-or-video-or-data).
Since power is provided by Intelsat, I am guessing that there will be ample power for transmitters. That might permit using smaller dishes for the mw digital mode. That might be 12 or 18 inches...or maybe permit use of a flat phased planar array (patches). 18-inch offset feed dishes are readily obtained from Direct-TV/Dish Network suppliers. Gain at x-band is about 32 dBi.
So I disagree that EMCOMM automatically implies big dishes or expensive custom transceiver (It should be a mw xvtr followed by a SDR plugged into a computer). I have no idea what the Eagle Team is thinking the SC-Rider package would run (Bob and guesses this early?).
Everything is speculation at this point! Ed - KL7UW
At 10:50 PM 12/20/2007, sco@sco-inc.com wrote:
P4 digital is for computer, right? something like psk31? The sat phones you are talking about use discreet channels, right? P4 will be using linear transponders, right? The user will need to tune the uplink and downlink to find a spot to communicate? Hams don't have "channels" on a sat, right? we are not talking a new CB here are we? P4 will have SSB 2m/70cm for one transponder and X band/S band for the other? My S band dish is about 3 feet in diameter. A little large to fit on a sat terminal's cover. I do not want to have to buy a new terminal built by Amsat (or some such agency) that costs me tens of thousands of $$. A good system will let hams use their off the shelf equipment. Those sat terminal phones you speak of are very expensive and not that good for transfering video (as proposed for P4). Have you seen the poor quality from those terminals that shows up on FOX network? Seem fine until an object moves then is badly distorted. We need a much higher quality system if we are serious about emergency commo. That requires a much larger ground station "terminal" and antenna system, and operator training.
Les W4SCO www.scoincsoftware.com
-------- Original Message -------- Subject: RE: [amsat-bb] Re: The Whole GEO Package From: Edward Cole kl7uw@acsalaska.net Date: Fri, December 21, 2007 12:27 am To: sco@sco-inc.com Cc: amsat-bb@amsat.org
Les,
Then how do the "civilians" set up those nice mw satellite terminal phones? I have seen some that the case cover is the antenna and it comes with a compass. The cover is rotated to settings from a chart. Flip a switch and pick up the handset.
The digital stuff of P4 will "inside" (sort of like Intel is inside my computer). With good packaging and instructions I think it can be made simple enough. I am kind of hoping that the main-stream P4 will be more generic satellite that requires some skill in operation, but for the EMCOMM unit KISS.
Ed - KL7UW
At 04:32 PM 12/20/2007, http://email.secureserver.net/pcompose.php#Composesco@sco-inc.com wrote:
To believe that a traditional ham who operates HF or even on 2m repeaters is going to be able to setup and operate the P4 satellites is a fool's game. Hanging a wire in a tree is a lot different than pointing microwave antennas at a set spot in orbit. Then the sat is basically running "split" something that i doubt many hams know how to do with their radio. Then if we are talking about operating in a digital mode that is another new set up learning skills for the ham op to learn. You can not send an untrained ham to a site and expect them to setup and operate P4 in a microwave digital computer mode. it just will not happen. A lot of people can not even read a compass so they won't be able to even aim the antenna(s). And then what about the proper elevation? How is the ham to do that without tracking rotors? yes it can be done by hand but there must be a way to measure the angle of elevation and azimuth from the antenna to the satellite. Looks like we will need to develop a lot of training to make EMCOM work with any operators other than old Amsat hands. Maybe we could have an award/training program? After a ham works 50 contacts via P4 they might be considered qualified to help teach other non sat hams how to do it.
Les W4SCO
-------- Original Message -------- Subject: [amsat-bb] Re: The Whole GEO Package From: Edward Cole
<http://email.secureserver.net/pcompose.php#Composekl7uw@acsalaska.net>
Date: Thu, December 20, 2007 10:30 am To:
http://email.secureserver.net/pcompose.php#Composebrobertson@mta.ca, http://email.secureserver.net/pcompose.php#Composeamsat-bb@amsat.org
At 04:29 AM 12/20/2007, Bruce Robertson wrote:
In this spirit, might I ask this list to imagine what needs to be done to make the emcomm/geo package a reality? The following is my rather long analysis of the situation.
I believe the proponents of the Intelsat agreement have done us a great service by identifying a real and persisting need which AMSAT can uniquely fulfill. By doing so, they not only greatly increase our chances
of funding
otherwise prohibitively expensive launches, they give our branch of the hobby a greater reason to do what we do.
However, I also think the EMCOMM branch of our hobby has different needs than the usual satellite station operator. If we are to really
and honestly
make the world a safer place and save lives, I think we will need to provide a GEO EMCOMM package that will require us as a organization to branch into some new and exciting efforts. Let me explain what I mean.
Traditionally, a satellite station has been developed through one person's expertise gradually growing regarding a number of interrelated
aspects: low
signal VHF and UHF operation; the mechanics of an az-el antenna array; computer control; and doppler correction. Certain satellites or operating habits allow one to omit one or more of these, but in general
it's, even by
ham standards, a challenging array of new skills and
understanding. I'd say
the members of AMSAT are self-selected as those who enjoy this challenge and seek to learn as many aspects of the field as possible.
However, for an EMCOMM system to be effective, it cannot rely on a broad array of such specialized knowledge: it is unreasonable to expect that the first ham on the scene of a disaster will be one of the AMSAT 'us', a person who has acquired this specialized knowledge. It is only reasonable to assume that it will be an amateur radio operator, familiar with the general principles of radio theory and operation. In fact, in my
region the
EMCOMM specialists and the technical specialists (if I might put it that way) are often not the same people.
So our challenge is more extensive than the challenge that faced
AMSAT with
any previous launch: we need to make communication through this bird possible for any ham shmoe who is opening up a box of equipment after, say an afternoon of instruction half a year ago. Please note, this is not a matter of dumbing-down the bird or making it uninteresting. In fact, for the old-hands and the technically adept around here this will be very interesting and a great outlet for our skills. In this application, if not on all birds, we should take it as a sign of success when people effortlessly get connected, because it would mean that, in a
true emergency
there would be a greater likelihood of useful service.
If this analysis is accurate, we need to imagine, broadly, three
things: a)
the services (or modes) this ham will offer to support EMCOMM; b) the box of stuff that this ham opens up; c) the afternoon's training she undertook to know how to use it. These are interrelated, of course. The training is apropos the box of stuff, and the box of stuff allows the services. They should also, I think, be *standardized* to an extent that has not been the case before with satellite work. Recently I heard the argument on Amateur Radio Newsline that ham EMCOMM services should be more interchangeable across the continent; the same will surely be the case regarding
this work.
Ideally the 'stuff' and the training is the same everywhere so that the shmoe has a chance of recollecting her training and is required to factor out/in as few local variables as possible.
The advantage we have is that it isn't unreasonable to expect the box of stuff to be perhaps more pricey than individual hams would like
such things
to be.
A large part of a) and b) will be determined by the ACP team, whose goal even with Eagle was to provide ground-station hardware alongside
the bird's
hardware. (The wisdom of this new approach should be applauded;
I'm sure it
has made re-purposing Eagle hardware for P4/EMCOMM much easier
to imagine.)
As I've argued before, I think one of the most important mode we can offer is simple Internet connectivity, allowing the emergency services folks to use the communication tools like email with which they are most
familiar. I
hope this will be part of the mix. As for the second half of b) and c), I think it will focus around designing and teaching the use of software. Perhaps the box of stuff will include a laptop that operates well with a specialized linux distribution-on-a-disk, including all the software tools needed to assess link quality, perform simple communication, etc. If I'm right, this is fortunate because we seem to have quite a number of adept software developers in our midst.
Finally, the course. Can we provide standard lesson-plans, ppt slides and the like? I think this would significantly lower the bar on each of us teaching a session on P4 to our local club or EMCOMM group.
I think we should spread the load on these tasks as early as possible, making many of us participants in the final goal of increasing the safety of our communities and nations. I'm excited to hear what others
think about
the broader implications of the P4 initiative and how we can
deliver on the
whole GEO package.
73, Bruce VE9QRP
Bruce,
This is an excellent topic to bring to the -bb.
Off course until the design of P4 has progressed, this is mostly
speculation.
The EMCOMM radio package will most certainly drive the satellite requirements, as well.
The ground package needs to be: 1- compact (portable) 2- standardized (so diverse groups can assemble a package) 3- well documented (both for assembly and use) 4- versatile to power (anywhere in the world) 5- robust (to endure rough handling; harsh environments) 6- easy to interface (with computing hdwr; telco; other ham equipment) 7- simple to assemble and aim 8- affordable 9- kit or ready to use (within reason considering the technology)
This should probably be close to the same package that the apartment user will have. This would expand the volume of units made. design be made available to commercial sector to provide units (fitting the spec).
Hope this gives a starting point.
73, Ed - KL7UW ====================================== BP40IQ 50-MHz - 10-GHz
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Edward Cole