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Text File | 1992-06-11 | 29KB | 785 lines

HamComm Version 2.1 June 11th 1992 W. F. Schroeder DL5YEC HamComm 2.1 Manual June 11th 1992 1. Introduction HamComm is a program for ham radio communications. Version 2.1 supports reception and transmission of amateur radio teletype and Morse code signals. A converter or modem chip is not required. The audio output of the receiver is connected to the serial port of any PC/XT/AT compatible computer thru a very simple and low-cost circuit. Only one IC is needed (Op-Amp LM741 or similar) and a few diodes, capacitors and resistors. The supply current is drawn from the serial port. For transmission the audio signal from the speaker or serial port is connected to the microphone input of the transmitter thru a passive R/C filter. Audio frequency generation and decoding, serial/parallel conversion and all other signal processing is done by the program. 2. License HamComm 2.1 is not in the public domain. The author keeps the copyright and all other rights. You are NOT allowed to: - make any modifications to the program - distribute the program without this file - take more than $10 for distribution including all costs You ARE allowed to: - use this program freely for any non-commercial purpose - make as many copies as you like and give them away If you like HamComm please send a contribution of $10 or more to the following address: Django Schroeder Augsburger Weg 63 D-4790 Paderborn Germany - 1 - HamComm 2.1 Manual June 11th 1992 3. Exclusion of warranty Because this program is licensed free of charge, the author provides absolutely no warranty, to the extent permitted by applicable state law. Except when otherwise stated in writing, the author and/or other parties provide this program "AS IS" without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the program is with you. Should the program prove defective, you assume the cost of all necessary servicing, repair or correction. In no event unless required by applicable law will the author and/or any other party who may modify and/or redistribute this program be liable to you for damages, including any lost profits, lost monies, or other special, incidental or consequential damages arising out of the use or inability to use (including but not limited to loss of data or data being rendered inaccurate or losses sustained by third parties or a failure of the program to operate with any other programs) this program, even if you have been advised of the possibility of such damages, or for any claim by any other party. 4. System requirements HamComm 2.1 will run under MS-DOS 3.x or higher on any PC/XT/AT-compatible computer with at least 320KB of free memory. A harddisk is not required. Because of the size of the program file there may be not enough space to copy all required files onto a 360KB diskette. On slow systems, e.g. 8088 CPU, some functions may not work as expected or may not work at all. HamComm will automatically detect the type of video adapter in use. MDA, CGA, EGA, VGA and Hercules are supported. The graphics display functions are not available on MDAs since the MDA has no graphics mode. No attempt has been made to avoid screen flicker (snow) on cheap CGAs. HamComm will probably not run under any kind of multitasking software like Desqview, Windows or OS/2 since it needs direct control of the interrupt controller, timer chip and serial I/O hardware. - 2 - HamComm 2.1 Manual June 11th 1992 5. Installation For installation on a harddisk you should create a subdirectory HAMCOMM and CD to that directory. HamComm is distributed as a .ZIP or .EXE file. To unpack a .ZIP file you need a program like UNZIP or PKUNZIP. The .EXE version is a 'self-extracting archive' that contains all the files and a build-in unpack program. In both cases the files will be created in the current directory. Please read the files README, HC.CFG and CHANGES ! 6. Startup To start HamComm type HC at the DOS prompt and hit ENTER. The interface circuit is not needed if you just want to play with the program. HamComm normally uses the currently selected video mode. If you have an EGA or VGA card with an EGA/VGA monitor you can also switch to 43 or 50 lines. Try option -L43 to switch to 43 lines on EGA/VGA cards or -L50 for 50 lines on VGA cards. Many SuperVGA cards have special text modes e.g. 80x60 or 132x44. Activate the desired mode before starting HamComm. Most cards come with a utility program to do this. Only the modes where the video display buffer starts at segment B800 are supported. HamComm assumes that the original PC display character set known as "codepage 437" is active. On startup the program identifies the video card and monitor in use and automatically selects the graphics mode for highest resolution. Some program functions require a graphics mode for display of the input signal. The identification may fail because of compatibility problems. By selecting one of the following commandline options HamComm can be forced to use the specified mode: Option Mode Resolution -cga 6 640x200 2-color -ega 10h 640x350 16-color -vga 12h 640x480 16-color -herc Hercules 720x348 2-color - 3 - HamComm 2.1 Manual June 11th 1992 If you have a computer with LCD display and readability is poor try the following DOS command before starting HamComm: mode bw80 The 'mode' program is supplied with MS-DOS and is used here to switch to black and white mode. 7. Screen layout HamComm has an SAA-like user interface with pull-down menues, dialog boxes and online helptexts. The menue bar at the top of the screen is always visible if the program is in text mode. The bottom line has information about the currently selected menue item. Every name on the menue bar has a highlighted character. Press and hold the ALT key and type that character to select the corresponding menue. The cursor-left and cursor-right keys can now be used to switch to the previous/next menue. Use the cursor-up and cursor-down keys to move to the desired function and hit the ENTER key. Every menue line also has a highlighted character. Typing that character (without the ALT key) will get you directly to the corresponding function. Some frequently used menue entries have been assigned to function keys. The F8 key for example activates the SCOPE function. The ESC key can be used any time to abort menue selection. 8. Help system The ALT-H and F1 keys both start the help system. The ALT-H key displays general information about the program, the F1 key displays a help text specific to the current situation. - 4 - HamComm 2.1 Manual June 11th 1992 9. Interface schematics The interface schematics are included in the online help texts. 1. Start the program, 2. Hit ALT-H to start the help subsystem, 3. Hit the letter 'O' to select topic 'Overview', 4. Hit the TAB key to select topic 'Converter' and hit return, 5. Scroll the help text using the cursor-up/cursor-down keys and read the text. Hit ESC to leave the help system. 10. Receive circuit The operational amplifier (OpAmp) is used to bring the audio signal from the receiver up to RS232 level. The supply current is drawn from the DTR and RTS pins of the serial port. The four diodes (1N4148 or similar) of the receive circuit form a standard bridge rectifier. The 1uF capacitors are used for buffering. The input signal amplitude should be at least 100mVpp. The 100nF capacitor removes any DC bias. Since the OpAmp runs with maximum gain there will be a (more or less) rectangular waveform at its output. It should have an amplitude of at least +/-5V to reliably drive the RS232 input. The operational amplifier LM741 was choosen because it is inexpensive and widely available. However with todays technology its electrical characteristics are not impressive. An LF356 or TL071 for example is much faster and has a higher input resistance. If you want to substitute a different opamp type, keep in mind that the serial port can only deliver a supply current of a few milliamperes. - 5 - HamComm 2.1 Manual June 11th 1992 11. PTT circuit The RTS output of the COM port is not only used to provide the supply current for the opamp, but also to key the transmitter. A Diode is used to protect the base of the PTT transistor against the negative voltage of the RTS output in receive mode. The resistor is required to limit the base current. In transmit mode the RTS and DTR pins change polarity. RTS is now positive and the transistor pulls the PTT line to ground. This circuit has been tested with an FT747, FT757GXII and a TS440S. On some old rigs there may be a high voltage on the PTT line. The required current to key the transmitter may also be too high for a small transistor, so better check BEFORE connecting it to the computer. 12. Transmit circuit AFSK tone signals for transmission are available at two places: 1. at the speaker connector 2. at the serial port. With many motherboards one side of the speaker is connected to the +5Volt supply thru a resistor, the other side is pulled to ground by a transistor. In contrast to most other areas of the PC's hardware there is no standard design for the speaker output, so there may be variations. In general one side of the speaker will be near ground or +5Volt, while the other side has a square-wave signal. This signal is fed to two R/C filters to smooth it out. The microphone input is very sensitive so a variable resistor is used for attenuation and a capacitor to remove any DC. If you don't want to make any modifications to the PC or the speaker output is not accessible, you can also get an AFSK signal from the TxD pin of the COM port. The frequencies are not as accurate as at the speaker output and will often deviate by 5 to 10Hz, but this usually gives no problems. The signal level at the TxD pin is much higher than at the speaker output, so you probably have to change the component values for the R/C filter and the attenuator a bit. - 6 - HamComm 2.1 Manual June 11th 1992 13. External converter An option "External Converter" is available on the "Keying" menue. It can also be controlled by the ALT-F9/ALT-F10 keys. If this option is enabled, a mark/space signal from an external converter or modem chip is expected at the CTS pin of the COM port. Please note that the normal interface is still required. There will be no reception if it is not connected or doesn't get the audio signal from the receiver. Connect the input of the converter and the input of the HamComm interface in parallel to the receiver output. Filter converter for RTTY are normally designed to differentiate between two tones. For CW reception a kind of tone decoder is required that can tell the tone from noise. 14. External AFSK AFSK tones for transmission are normally available at the speaker output or the TxD pin of the COM port. If you don't want to use those signals for whatever reason, you can find an FSK signal at the DTR pin of the COM port. For RTTY transmission DTR is negative for 'mark' state and positive for 'space' state. In CW mode DTR is negative for 'no-tone' and positive for 'tone'. During reception DTR is always positive. Note that in receive mode the RTS pin is negative and always positive during transmissions. It can thus be used to gate the DTR signal for keying a transmitter in CW mode. If you attach any additional components to these pins please keep in mind that the DTR/RTS signals supply the power for the OpAmp. 15. Signal decoding The amplified audio signal is connected to the DSR modem status input of the serial port where every zero crossing generates an interrupt. HamComm determines the time between successive interrupts using the PCs timer chip and calculates the corresponding tone frequency. Due to the timer resolution of about one microsecond the result is quite accurate and constitutes the base for all further signal processing. - 7 - HamComm 2.1 Manual June 11th 1992 For RTTY decoding the tone is compared to the currently selected center frequency to decide wether this is a 'mark' or 'space' signal. The mark/space signal is sampled at the proper time according to the current baud rate collecting all bits of a character. For CW decoding the program has to differentiate the tone from noise. To be regarded a valid signal the tone has to be between the currently selected mark/space frequencies for a certain amount of time. The program maintains a floating average of the length of the dots and dashes to adjust to varying speeds. When the character is complete it is converted to ASCII code and displayed in the RX window. 16. Macro keys A macro key can be used to replay a previously recorded sequence of keystrokes. The digits on the top row of the keyboard are used as macro keys while the ALT key is depressed. They are normally located right above the QWERTY... row. Do not confuse these keys with the numeric keypad! In the beginning there are no keystrokes assigned to the macro keys, so pressing ALT-1, ALT-2...ALT-9 or ALT-0 has no effect. To start recording, select item 'Macro recorder' from the FILE menue. A message box will appear confirming that recording has been started. When the ENTER key is hit, the message box will go away and from now on up to 250 keystrokes will be recorded along with normal processing. A blinking "! RECORDING !" message is shown at the lower right corner of the screen to remind you that the recorder is still active. Now hit one of the macro keys to stop recording and to assign the keystroke sequence to that key. This also replaces any previous assignment. A message box will appear to confirm that macro recording has terminated. Every time the macro key is hit the recorded keystroke sequence will be replayed just like it had been typed again. To terminate recording without changing any macro key just select 'Macro recorder' again from the FILE menue. A message box will appear to confirm that macro recording has been canceled. - 8 - HamComm 2.1 Manual June 11th 1992 To clear a macro key start recording in the usual way and directly after that hit the key to clear. This will erase any previous recording assigned to that macro key. Again a message box will confirm the result. 17. Macro files Macro definitions can be saved to a file by selecting "Save macros" from the FILE menue. The usual file select box pops up with a suggested .MAC file type. All recorded keystroke sequences will be saved to the selected file. To load a .MAC file select "Load macros" from the FILE menue. All macro definitions found in the selected file will be added to or replace the current assignments. Macro keys that didn't hold any keystrokes at the time the file was written, will not be changed when the file is loaded. There is also a way to automatically load your favourite macros definitions. When HamComm is started it searches for the default macro file HC.MAC, first in the current directory, then in every directory along the PATH. 18. Scope function In RX mode the tone decoder routine calculates the current signal frequency for use by other parts of the program. The SCOPE function uses this value to display a graph of the input frequency vs. time. This is the blue line on the SCOPE screen. The tone decoder also maintains a floating average frequency. The effect is very similar to a low-pass filter and is used for noise reduction. The result is displayed at the top of the screen as a red line. The solid green line marks the currently selected center frequency and the dotted lines above and below show the mark and space tones. For RTTY reception the center line should be in the middle between the mark and space tones. For CW reception the signal should match the center frequency. All signals outside the area marked by the dotted lines are ignored. - 9 - HamComm 2.1 Manual June 11th 1992 The display can be controlled with the following keys: F1 display help screen F10 activate menue bar ESC same as F10 '+' toggle display of decoded signal '*' toggle grid display 'B' toggle position of red line HOME reset sample rate to 1ms PG-UP sample rate faster PG-DOWN sample rate slower ENTER hold display immediately The right mouse button holds the display at the end of the current sweep. The left mouse button activates the menue bar just like F10. The red line (input signal after low-pass) is normally displayed at the top of the screen to not interfere with the blue line. In its second position it will overlay the blue line to compare the two signals. Display of the decoded signal is normally disabled. It can be found at the bottom of the screen and shows the mark/space states for RTTY and tone/no-tone states for CW reception. With some practice it is quite easy to determine the signal you are listening to by watching the SCOPE display. CW, AMTOR ARQ and FEC, Packet Radio and RTTY show their characteristic patterns and you can also watch unstable VFOs sweeping slowly across the band. 19. Spectrum function On entry to the Spectrum function a graphics mode according to the video card and monitor in use is activated. Every millisecond the current input frequency is checked. For every frequency there is a counter and the one that corresponds to the current frequency is incremented. All counter values are displayed as vertical lines with each sweep from left to right. The higher the count, the longer the line. What you see on the screen is therefore not the true audio spectrum but the result at the output of the tone decoder routine. An opamp and a few lines of code can't substitute a real spectrum analyzer. - 10 - HamComm 2.1 Manual June 11th 1992 When set to 1Hz per pixel SPECTRUM has the best resolution of all display functions. For example, the actual shift used by an RTTY station can be determined quite accurately. The display can be controlled with the following keys: F1 display help screen F10 activate menue bar ESC same as F10 '-' toggle raw/filtered data '+' toggle 'shaddow' (color displays only) '*' toggle dot/line mode HOME reset, start at 200Hz, 3Hz per pixel PG-UP zoom in PG-DOWN zoom out LEFT lower frequencies RIGHT higher frequencies SPACE clear display ENTER hold display The right mouse button holds the display at the end of the current sweep. The left mouse button activates the menue bar just like F10. If you have a slow PC then don't use the SPECTRUM function, you might get frustrated. There simply isn't enough CPU power to keep the display in motion. AT class maschines and real fast XTs should be ok. The SPECTRUM function has been found to be quite entertaining, especially with a color display. Next time you got visitors in your shack who don't know what's going on just start this function, turn the lights low and sweep across a crowded band. - 11 - HamComm 2.1 Table of Contents Table of Contents 1 Introduction ........................................... 1 2 License ................................................. 1 3 Exclusion of warranty ................................... 2 4 System requirements ..................................... 2 5 Installation ........................................... 3 6 Startup ................................................. 3 7 Screen layout ........................................... 4 8 Help system ............................................. 4 9 Interface schematics ................................... 5 10 Receive circuit ....................................... 5 11 PTT circuit ........................................... 6 12 Transmit circuit ....................................... 6 13 External converter ..................................... 7 14 External AFSK ......................................... 7 15 Signal decoding ....................................... 7 16 Macro keys ............................................. 8 17 Macro files ........................................... 9 18 Scope function ......................................... 9 19 Spectrum function .................................... 10 i HamComm 2.1 Index AFSK output................6 CGA........................2 Converter, external........7 Converter..................5 CW.........................8 Desqview...................2 EGA........................3 ESC........................4 Exclusion of warranty......2 External AFSK..............7 external converter.........7 F1.........................4 Floppy.....................2 Function keys..............4 Harddisk...................2 Help system................4 Installation...............3 Interface schematics.......5 Introduction...............1 Laptop.....................4 LCD........................4 License....................1 Macro files................9 Macro keys.................8 Menue bar..................4 Multitasking...............2 Operational Amplifier......5 PTT circuit................6 Receive circuit............5 RTTY.......................8 Scope function.............9 Screen layout..............4 Selection..................4 Signal decoding............7 Speaker....................6 Spectrum function.........10 Startup....................3 SuperVGA...................3 System requirements........2 Transmit circuit...........6 VGA........................3 Video adapter..............2 Windows....................2 XT.........................2 i