[Namaste-dev] Re: System Block Diagram - Version 1, and other matters
w5nyv at yahoo.com
Thu Jun 26 16:03:08 PDT 2008
I appreciate the offer, but I cannot accept your software proposal (if it is intended for the ground station effort) at this time.
Joanne Maenpaa is leading a P25 requirements analysis effort. Her plan can be found here:
This P25 study is not complete.
We won't begin the software until this, and the other studies that support a set of software requirements (such as the FH-FSK analysis), are published and reviewed as widely and as well as they can be.
----- Original Message ----
From: Bob McGwier <rwmcgwier at gmail.com>
To: Michelle <w5nyv at yahoo.com>; namaste-dev <namaste-dev at amsat.org>
Sent: Thursday, June 26, 2008 9:56:27 AM
Subject: RE: [Namaste-dev] System Block Diagram - Version 1, and other matters
This is as good “big picture” as we can get. Thank you for this.
I want to give you all some data points. What follows is information unrelated to my ego. Please take it as such.
In my work on the REAL dark side of the force as opposed to the “obscure” signature below ;-), I have some experience of what can be accomplished in the real world and am completely compared to help begin implementation of this along with the corresponding half on the other side.
With a USRP2 and a modern PC, I can prototype this very quickly indeed if we do not do the FH-CDMA. Matt tells me “my” USRP2 are close to “in the mail”.
I will be meeting with Rick on Sunday and I will brow beat him about getting an svn repository up so we can begin this.
Let me give you a data point. On a single Dell 2950 with two Quad core Xeon at 3.16 GHz, I can do all I/O and process down to bits communications channels of all sorts of signal channels in parallel. I do, day in and day out, processing of 70 channels, each one MHz wide, where I process for energy alarms, classify the content, decide to send it down to a narrower band processor and run all of those. There are literally thousands of threads in this system and some of the demodulation and decoding (forward error correction and removal of interleaver) is intense. It uses the sdr core you can blame AB2KT and I for having started.
This is not bragging, please believe me. If I wanted to brag, I would have told you about it ages ago when it was first done (and told you I can process more data than Vanu can on his servers ;-) ). I bring it up to try and move us to something concrete as quickly as possible and to demonstrate my strongest possible belief we can, so we have stuff to show in October.
We have, as demonstrated in Paul’s diagram, an almost completely software defined system. I have a novel idea. Let’s write some software. We have the necessary tools available to this project in the USRP2 and Gnu Radio to do rapid prototyping of this system. We should. It will cost only a few thousand dollars to do the entire ground station software prototype out to baseband and even build a spacecraft simulator in the same space.
We can use existing plug in cards for the USRP2, again inexpensive, to move it to RF. These are NOT in our bands but we are not trying to do the initial experiment in the amateur satellite service. We want to operate this for our own education and to build towards presenting an experimental R&D system to first responders in Southern California. I have done P25 implementations for work. I won’t be sharing those and I won’t be writing them personally but I will be happy to “lead” others to the successful implementation when we get ready to provide some kind of interoperability.
So, I am going to lead this off. It being open source and built using open source, I need no one’s permission to start and I hope you will follow. It will be open to any and all who want to develop code for download and to a more limited set of developers for upload. I can provide the shell of this block diagram in Gnu Radio blocks pretty quickly so we can begin adding the pieces for experimentation.
ARRL SDR Working Group Chair, AMSAT VP Engineering.
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
“Trample the slow .... Hurdle the dead"
From:namaste-dev-bounces at amsat.org [mailto:namaste-dev-bounces at amsat.org] On Behalf Of Michelle
Sent: Tuesday, June 24, 2008 1:30 PM
Subject: [Namaste-dev] System Block Diagram - Version 1
Here is the current block diagram. It's in the feed and on the web. We expect it to change, of course, but we wanted to post it for review and comment.
Potestatem obscuri lateris nescis.
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