Been a very busy month

I have IPS (see IPS ) running on the AMSAT IHU-3. The IHU is the internal housekeeping unit of the spacecraft. It receives and processes commands, it maintains the state of the spacecraft and attempts to mitigate faults and generally manage the health of the spacecraft. I have pictures of our meetings in Germany and Washington state in these gallery entries:

Germany: Germany IHU-3 pix

and

Washington: Washington at KK7P IHU-3 pix

We can talk to the bus of the spacecraft and programming of the IHU flight code has commenced.

The American Radio Relay League sponsors technical working groups. I am chairperson for the Software Defined Radio working group and a member of the High-Speed Digital Networks and Multimedia Working Group. We are working on a class of modems ideally suited for both HF and VHF and Microwave communications. The modem class is called OFDM and this is orthogonal frequency division multiplexing. This is a fancy name for sending a bunch of data down parallel channels (parallel in frequency) and done in a way that the frequencies used provide an very nice mathematical property which aids considerably in the modulation and demodulation of these signals.

AMSAT will be holding a board of directors meeting and AMSAT Eagle spacecraft design meeting in Pittsburgh Oct. 6-9. I will be demonstrating with my partners a working software defined transponder SDX. You can hear the first QSO by visiting

GPS Time page with SDX pix and audio

Please visit the last bulleting and you can download and listen to the audio.

The ARRL review of the work Frank Brickle (AB2KT) and I have done, in cahoots with the folks at Flex Radio is available here:

ARRL Review of SDR-1000


By the time of my next entry, I will know if I am on the board of directors of AMSAT. I was talked into it, I have done it before and chose not to run back when AEA failed and amateur radio lost its luster. I am glad it has regained it.

August 2, 2005

I have managed to get the IPS-E0 image (the basic IPS operating system) into the bootloader for the IHU-3 (integrated housekeeping unit for Phase 3E and Eagle). It will be easily loaded via the bootloader by just striking the E key. This enables us to upload, using the bootloader, any type of IO, interrupt handler, etc. that we wish to upload. This should greatly speed the development process for the flight code for Phase 3E.

I have added some CAN controller initialization code to the bootstrap IPS routine as well as an asynchronous communications mechanism. It will use the flag facility already built into IPS to send and receive 512 byte blocks but it will be almost completely limited to printable ascii characters.

On the SDR-1000 front, I modified some of the settings for the "microphone leveler". It appears that we have too much early attack which appears to limit the average power too much. It may be that we never wish to allow for negative gain at this stage.

It is clear that serious investigation of this process is required. I only wish I could force myself to be interested in doing it. Sigh.

The SDR-1000 official numbers are in. 99 dB IMD-DR and +27 dBm IP3 on the low bands at 2 Khz with the preamp in medium setting (giving <-120 dBm MDS). OUTSTANDING.

Bob