Micro908 DSP Audio Filter
AF908
AF908 is a software package
for the Micro908 kit, produced by the American QRP Club, that enables the
Micro908 to perform as an audio filter utilizing the popular KK7P DSPx
Daughtercard. This daughtercard is an optional component in the Micro908, and
when combined with the AF908 control software, it serves as a free-standing,
portable and extremely programmable DSP that can be used to enhance the audio
performance of an amateur radio receiver.
[NOTE:
You must have the DSPx Daughtercard installed on the Micro908 motherboard
connectors J8 and J9 for the Micro908 to run the AF908 software and to perform
as a DSP Audio Filter.]
The AF908 software runs on
the Micro908, providing the user interface for control of the instrument and
for control of the internal DSPx card. Two
fully-functional DSP audio filter programs are also included that allow the
DSPx card to provide its comprehensive filtering capabilities. One filter
program provides capabilities similar to the Elecraft K2’s KDSP2 filter
(which also uses the DSPx daughtercard): fully-programmable audio filters for
CW, SSB and data (RTTY, PSK31, AMTOR, et al) .
The other filter program provides a robust suite of DSP filter
programs, such as a BFO, an LMS denoiser, a Wiener-filter autonotcher, and
other filters using multi-rate processing, adaptive filtering and frequency
shifting techniques.
Once
one or more DSP programs have been loaded into the nonvolatile memory of the
Micro908, the platform becomes a fully-functional DSP filter that can operate
independently of a PC. In addition, the tools necessary to modify and develop your
own DSP applications are included in the package.
Block Diagram of the
Micro908 “AF908” Digital Audio Filter
As can be seen above,
AF908 software does not utilize any of the RF paths in the Micro908 used
previously by the Antenna Analyst software, nor does it require the DDS card.
The AF908 control program running on the HC908AB32 control processor only
utilizes the DSP daughtercard, the SEEPROM nonvolatile memory (for storage of
the programs to be run on the DSPx card), and the user interface hardware of
the instrument itself (pushbuttons, LCD, dial, and audio paths.
After the preliminary
instructions for getting the Micro908 updated and the AF908 software
installed, this User Manual will guide you on how to run a simple DSP program
and verify that all the components of the AF908 system are working. The manual
will then cover the basic operations of the two DSP software components:
DSP908 and ASP.
There are many
options available in the AF908 software package, some of which will only be
used by a few users or used very infrequently, so we have included a complete
reference covering all the available options. Manual appendices describe the
contents of the AF908 package, the default values for all the options,
information on developing DSP programs for the Micro908/AF908 system, and
information on the format and protocols for downloading DSP programs to the
Micro908.
AF908 User Manual
The User Manual, written by Steve
Holton, N1NB, provides a complete description of the installation and use of
the AF908 software. (Note, a minor pcb trace modification is required
before you can install and use the DSPx daughtercard. See the appendinx
in the Manual for the easy steps required for this.)
Download AF908 User Manual
(Right-click link and "Save target as ...
" to your computer)
Software
1) You must download and install the
AF908 software on your Micro908 in order to run the DSP audio filter
capabilities. Get this software on the Micro908 main
page. The AF908 "s19" file is loaded into your Micro908 platform as you have normally done when
installing updated
software. (See the section for "Loading New Software" in the
User's Manual.)
2) You must also download
the "DSPterm.exe" program that runs on your PC, as well as the DSP
files that get loaded by it. You should place this file in a new
folder named "DSPx" (for example). DSPterm may be run by
double-clicking the filename in the Windows File Explorer window, or for
more flexibility as described in the User Manual, in a Command Prompt/DOS
window.
Download DSPterm.exe and
Download
DSPimage.exe
(Right-click each link and "Save target
as ... " to your computer)
3) Five DSP programs (DSP908.exe,
ASP.exe, C1SIN.exe, C1SIN2.exe and C1FIR.exe) are
provided. For simplicity, these five DSP programs should all be placed in
the same directory as used for the DSPterm and DSPimage executables in step
2.
DSP908.exe
ASP.exe
C1SIN.exe
C1SIN2.exe
C1FIR.exe
(Right-click each link above and "Save
target as ... " to your computer)
4) If you are a software
developer, you might wish to modify the AF908 source code that Steve
Holton is making freely available (for personal, non-profit use).
You can get these source file in the Software section on the Micro908 main
page.
Support
Steve Holton, N1NB and George N2APB are
available on the Micro908 reflector to answer questions about installation and
operation.
Again, thanks very much to Steve for his
massive and near-single-handed effort in making the AF908 project a
reality. And thanks too to Lyle Johnson, KK7P for his guidance in the
project and helping us to use his DSPx Daughtercard in the Micro908.
