This WEB site is dedicated to the design of the HF transceiver with DSP IF processing.
This design is the result of the more than 2 years experimenting, writing software and designing hardware.
The goal of this project was to build a high performance HF transceiver with DSP IF processing. I did not try to archive as high parameters as possible, I just tried to get most from the available technology (i.e. mechanical and electrical parts and assembly technology). I tried to keep the design as simple as possible. The design widely uses "software" techniques that allows easy modifications and opens new possibilities (especially for such experimenter like I am :).
The transceiver hardware is completed and the first version of software too (but I am actively improoving it). You can view the measured specifications here.
As I said before I have widely used "software" techniques in this transceiver. There are two microcontrollers (first MSP430F149 is used as control processor and the second MSP430F123 - in synthesizer), one DSP processor (Motorolla DSP56362 @ 120MHz) and one CPLD chip.
You can see the control board on this picture. Many SMT components are on the bottom side of the board and under the MCU (MSP430F149) sub-board.
The control software is written mostly in C with some assembly fragments. I have written a real time operating system specially for this transceiver control program (you can visit it's WEB-site here), it saves a lot of coding time and makes programming much more efficient. At the present moment the control software has more then 15000 lines of C code. It consumes 41KB of flash (I have 19KB more for further development :). I used free msp430-gcc compiler.
The information is diaplayed on the graphic LCD (128x64) with yellow-green LED backlit. The control software uses mulilevel menus and provides control for a lot of different parameters.
|The "home" screen. The icons on the left and right shows the current fuction of the multifunction keys. The multimeter can be switched off.|
|If you want to browse the memory contents just press one key and you are in the memory screen. If you want you can enter a short comment for each memory cell (English and Russian are supported).|
|The sweep screen is helpful in checking conditions on the "dead" bands or finding clean frequency for calling or ... it is just a cool thing :).|
|An automatic memory keyer with automatic contest number generation is just what is needed for contesting. The number format can be chosen from the 5 different formats.|
RTTY decoder is implemented in software now. You can enjoy receiving RTTY without any additional equipment! The transmit capability will be implemented later (it will require only software updating, since AT keyboard interface is already there).
Now the tuning indicator (two bars just below the frequency line) and AFC are implemented also.
The DSP module is shown on this picture. You can see an analog section (on the left) and digital (on the right). The 24 bit DSP56362 is mounted on the sub-board (it simplifies PCB design). The DSP software is stored in the 256KByte AT29C020 flash memory chip.
The DSP software is written in assembly language. The filters coefficients are calculated using MATLAB program. The DSP is operating at 120 MHz (it is capable of up to 120MIPS/MMACs and 600 MOPS). The current version of software uses approx. 40% of its processing power. The control processor "talks" to the DSP processor via SPI bus.
For more information go to the DSP page.
The transceiver uses aluminium chassis and home made PCB boards. Most boards are screened.
|You can see packaging of the transceiver on the top view. The RF bay is on the right and LO bay on the left. The power amplifier, LPF filters and SWR meter are on the rear panel. The control board, LCD and button boards are on the front panel. The DSP module is on the center.|
Here is the bottom view. I used a high quality optical encoder from the old NC machine (it produces 2500 pulses per revolution; it is very handy to have a lot of pulses with a small step size provided by synthesizer). The AF and switching boards are under the encoder. The RF preamplifier did not fit in the RF bay, so I had to move it to the center chassis bay (a small box in the left part of the center bay).
I used connectors to connect front and rear panels to the chassis, so I have a convenient access for secvice to all boards.
|The RF bay. Here are BPFs, RF board and IF board (from left to right). As you can see I used 4 pole xtal roofing filter. Another 2 pole xtal filter after the 1st IF amplifier removes amplifier noise from the image.|
The LO bay. The lower board is the second LO. I used a simple xtal oscillator. The old (very old) large xtal cristal is used, because I could not found the xtal with the necessary frequency and had to polish the cristal to move its frequency higher (it is relatively easy with the old xtals).
The upper board is the synthesizer. The transceiver uses a modern forth-order sigma delta fractional-N synthesizer. It is very simple, but provides the necessary parameters with the minimum analog components (An article about it has been published in Nov/Dec 2003 QEX ).
|The back of the front panel. The control board is on the left. The LCD and encoder are on the center and analog meter on the right.|
|The back of the rear panel. The power amplifier board is mounted on the radiator under the LPF board. (Note: One of the five LPF filters is not installed yet).|
|The rear panel. The two SO-239 jacks for antennas and ground terminal are on the left. The DB-15 conectors for AFSK and external power amplifier and RS-232 computer interface are under the radiator. The tree jacks on the right are used for (from top to bottom) AT keyboard (does not work yet; will be used for PSK31, RTTY and CW transmitting), PTT and paddle/keyer.|