B T L V 1.54c - H E L P 1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Using Help: Use PG UP, PG DN, SPACE, or type page number [Enter] to move
~~~~~~~~~~ through help screens. ESC returns to demod screen.
Keys:
~~~~
F1 This help screen ALT-X Quit or Abort transmission
SPACE Force letters mode Arrows Tune centre freq +/- 25 Hz
F Force figures mode CTRL / Tune centre freq +/- 5 Hz
R RXR Mark/Space reversal ALT / Tune centre freq +/- 1 Hz
N NAR narrow filter mode Up/Down Select default centre freq
U UNS unshift on space toggle , or . Reduce/increase baud rate by 5
L LOG open/close log file < > or ; : Reduce/increase baud rate by 50
D Display mode, 43/50 lines ALT , or . Reduce/increase baud rate by 1
I I/O control panel CTRL-PG/ Variable shift +/- 10 Hz
H Hold, Pause demodulation ALT-PG/ Variable shift +/- 1 Hz
S USB/LSB mode PGUP/PGDN Select preset shifts
Enter New line B Select US/ITU2 Baudot standard
Home Clear screen ALT-W Word transmit mode toggle
T TX mode ESC End TX mode
E EXTended mode, auto detect ALT-E EXT mode (always on)
C Change case (upper/lower) ALT-C EXTF mode, fixed case
ALT-Fn Edit function key text ALT-P Store WHITE shift/centre freq
C O N T E N T S 2
~~~~~~~~~~~~~~~~~
Using help .................................... 1
Key definitions ................................ 1
Contents ....................................... 2,3
Program description ............................ 4
Features ....................................... 5
Setting up the Sound Blaster ................... 6
Transmit setup ................................. 7,8
Demod screen ................................... 9
Audio level adjustment ......................... 9
Tuning in a signal ............................. 10
Centre frequency, shift, and baud rate ......... 11
NAR - Narrow filter mode ....................... 12
Decoding to upper or lower case ................ 12
Extended Baudot operation ...................... 13
Automatic Extended Baudot detection ............ 13
Forcing Extended Baudot decoding ............... 14
Fixed case Extended Baudot decoding ............ 14
RXR - Mark/Space reversal ...................... 15
Sideband selection ............................. 15
Continued next page... Press SPACE, PG UP or PG DN
C O N T E N T S - continued 3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Forcing letters or figures shift ............... 15
UNS - Unshift on space ......................... 16
LOG - The log file facility ..................... 16
43/50 Line mode ................................ 16
Pausing demodulation - Hold .................... 17
Forcing a new line ............................. 17
Clearing the screen ............................ 17
Transmit mode .................................. 17
Word TX mode ................................... 17
Function Key Text Buffers ...................... 18
Brag files in TX mode .......................... 18
Function key text references in a Brag file .... 19
Default settings and BTL config file ........... 19
I/O Control Panel, I/O audio levels & PTT port .. 20
RTTY and the Baudot code ....................... 21,22
Baudot Standard Selection ...................... 21
Extended Baudot ................................ 23
Glory page ..................................... 24
Registration ................................... 25
Copyright ...................................... 26
P R O G R A M D E S C R I P T I O N 4
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
BTL - Blaster TeLetype, is a radio teletype (RTTY) modem and terminal. BTL
can decode RTTY transmissions found on the short-wave bands and generate
audio tones for transmitting RTTY using an SSB transmitter.
There are many different types of RTTY codes, however BTL will only receive
and generate the Baudot code, used by radio amateurs and many other services
such as news and weather bulletins. Many other services are encrypted.
You will need a Sound Blaster compatible sound card and an SSB receiver
or transceiver covering HF (short wave) frequencies. To receive you only
need connect the audio from your receiver to either the Mic or Line-In input
of the Sound Blaster. Select the input and adjust the tuning and audio levels
as described in 'Audio Level Adjustment', 'Tuning', and 'Sound Blaster
Control Panel' on pages 9,10 and 20. The decoded characters are displayed on
the screen and can also be written to a log file using the LOG function.
Refer to 'Transmit Setup' on page 7 for transmit instructions.
BTL uses the DOS environment variable BLASTER to find your sound card. This
is usually set up when you install your sound card, see 'Setting up the Sound
Blaster' - page 6.
B T L 1.54c F E A T U R E S 5
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
o High performance RTTY Reception and Transmission
o Function key TX buffers (on line editing), plus text file transmission
o On screen tuning and level indicators
o Fully adjustable centre frequency and shift, with standard presets.
o User definable preset shift and centre frequency
o Fully adjustable baud rate, 25 to 200 Baud
o USB or LSB default Mark/Space polarity for receive and transmit
o RXR Mark/Space tone reversal on receive
o Narrow/Wide tone filter option
o Unshift on Space (UNS)
o Extended Baudot, HAMCOMM compatible, plus US and ITU2 baudot standards
o Received text logging to a file
o 43/50 line mode
o Manually forced letters or figures shift
o Manually forced New Line and Clear Screen on demod screen
o Demodulation pause key (Hold)
o I/O levels, tones, and many other parameters saved between sessions
o Support for Sound Blasters version 1.0 through AWE32
o Sound Blaster parameter validation
o On-Line HELP!!!
o Bright Colours!
S E T T I N G U P T H E S O U N D B L A S T E R 6
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
BTL requires a Sound Blaster 1.0 compatible or greater.
Hardware parameters, Address, IRQ, and DMA channel should have been set up
when your card was installed. BTL reads the BLASTER environment variable
to get this information then checks to make sure it is correct. There should
be a line in your AUTOEXEC.BAT file something like this:
set BLASTER=A220 I7 D1
The numbers will depend on your card, and there may be more parameters.
If BLASTER is not set or invalid, BTL will prompt for hardware parameters.
Refer to your sound card manual to determine these settings.
On SB pro's BTL will use the Line-In input by default. The input can be
selected using the 'Sound Blaster control panel'- p 20. (SB pro & above only)
On older cards without AGC on the MIC input, you may need to turn the audio
level down quite low or add a resister in the audio lead to reduce the level.
If no card is found BTL will still run, however nothing will be decoded.
Transmit setup on the next page.
T R A N S M I T S E T U P 7
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Transmit mode is started by pressing 'T' and ended by pressing 'ESC'.
BTL will generate audio tones at the Sound Blaster speaker output
corresponding to the centre frequency, shift, baud rate and sideband mode
selected for receive, except if RXR is on then the transmitted tones will be
reversed compared to the received tones. Refer to 'Transmit mode' and
'Sideband mode' for details.
In some cases the sound blaster output can be connected directly to the
audio input of the transmitter. Unfortunately this is not normally the case
due to 1. High audio levels from the sound card, and 2. ground loops picking
up mains hum and the TX modulation envelope. Also it is a good idea to filter
the leads connecting your PC and transmitter when transmitting to ovoid
RF getting into your PC and crashing or even damaging it!
Ground loops are horrible. Problems are caused by high currents in the ground
leads (either due to the mains or 12V TX currents) causing a small AC
voltage along the ground wires. If the PC and TX have different ground
connections then this voltage will be seen between the two grounds and unless
the connecting ground wire is very, very thick they will add to the audio
causing buzzes. The problem gets worse as audio level is turned down!
But there are solutions, read on...
T R A N S M I T S E T U P (continued) 8
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The easiest way to stop ground loops, reduce audio level and put an RF
filter in the TX lead is with a small cheap audio transformer, a couple of
capacitors and maybe 2 resistors if the level is still too high.
1k : 8 ohms
Centre ------+----. .---[R1]---+-----+------ TX audio
| : | : | |
To PC [C1] : | : [R2] [C2] To Transmitter
| : | : | |
PC Ground ------+----' `----------+-----+------ TX Ground
T1
C1, C2 are 1nF, R1 and R2 form a voltage divider, say R1=3k3, R2=1k.
T1 is an audio speaker transformer of the several Kohms to 8 ohms variety,
configured to transform the voltage down. The two sides MUST be separate.
A telephone line transformer may be used, but with a 47k and 1k divider.
A resistor-capacitor RF filter in the receive would be a good idea too when
transmitting. 1n0 to ground, series 100R, 1n0 to ground in a ã configuration
BTL may use VOX or the RTS pin of a COM port to key the transmitter. (pg 20)
D E M O D S C R E E N 9
~~~~~~~~~~~~~~~~~~~~~~~~~
This is the normal operating screen you see when running BTL. Two indicators
are displayed at the top of the demod screen, the Tuning Indicator on top
and the Level Indicator below it. At the bottom of the screen is the Status
Line. The status line displays the Centre frequency, Shift, Baud rate and
the state of the RXR, EXT ,NAR, UNS, LOG, and HOLD functions.
Audio Level adjustment:
~~~~~~~~~~~~~~~~~~~~~~~
Adjust the audio output level of your receiver so that the level indicator is
roughly half way across when receiving a RTTY signal. Higher levels will
not improve performance, but may make it necessary to keep readjusting the
audio level when you tune to another station. Some cards have an Automatic
Gain Control on the MIC input. This automatically adjusts the input
sensitivity to keep the indicator at a constant level. If this is used, you
only need to ensure you are not driving it so hard that it still goes off the
scale. It's OK if it peaks to full scale occasionally. On SB 16's and above
the level the AGC adjusts to can be set.
The Input socket, input sensitivity, and AGC can be adjusted and selected
from the Sound Blaster Control panel. - See page 20
Tuning: 1275 Û Û 1445 10
~~~~~~~ ^
The tuning indicator is similar to those found on modems like the PK232.
The levels of the two tones are subtracted to produce a signal that is
positive (right) for high tones, and negative (left) for low tones. The
positive and negative peaks of this signal are displayed on the tuning
indicator. The numbers at each end of the tuning indicator are the centre
frequencies of each tone filter.
When a signal is correctly tuned both the positive and negative peaks
should flicker to about the same distance from the centre marker ^.
If the signal is off tune, one side will be stronger than the other. If the
Higher frequency is stronger, the pitch of the tones is too high. If the Low
frequency side is stronger, then the pitch is too low. To correct this
you can either adjust the tuning of the SSB receiver OR move the centre
frequency lower/higher using the left and right arrow keys.
Fine tune the signal to maximise the level of both sides of the indicator.
Using the narrow filters (NAR) will make tuning more tricky.
Centre frequency, Shift and Baud rate: 11
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Centre frequency, Shift and Baud rate may be adjusted in fine or course
steps as described below. In addition Centre frequency and Shift can
be set to pre-set values using PGUP/PGDN for Shift and Up and Down
arrows for Frequency. Selecting a pre-set centre frequency sets the
default centre frequency at startup.
One preset shift and centre frequency (displayed in WHITE) is adjustable.
To store a new preset value, select the adjustable shift or centre frequency
so that it shows WHITE, adjust it to the desired value, then press ALT-P to
save the new setting. This value is saved between sessions in BTL.CFG.
Adjusting Baud: , or . -/+ 5, < or >, or ; or : -/+ 100, ALT-, or . -/+ 1
Up or Down Arrows Selects preset centre frequency
PGUP or PGDN Selects preset shift
Left or Right Arrows Adjusts centre frequency in steps of +/- 25Hz
CTRL-Left or Right Arrows Adjusts centre frequency +/- 5 Hz
ALT -Left or Right Arrows Adjusts centre frequency +/- 1 Hz
CTRL-PGUP or PGDN Adjusts shift +/- 10Hz
ALT -PGUP or PGDN Adjusts shift +/- 1Hz
NAR mode (N): 12
~~~~~~~~~~~~~
If NAR is not lit on the status line then the demodulator is using 'wide'
filters for the Mark and Space tones. These filters are about 200 Hz wide
(half power bandwidth) and two have deep nulls around +/- 170 and 200 Hz.
These filters make tuning broad and easy while still effectively filtering
each tone from noise and interference and separating the two tones.
In NAR mode ideal MATCHED filters are used. The width will depend upon
baud rate, but for 45 baud they are very narrow making tuning tricky.
If you are listening to several stations you may need to retune for each
over if NAR mode is used. Narrow mode theoretically has slightly better
noise and interference performance but is of limited practical value.
Display Case (Upper or lower) (C):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The received text can be displayed in either upper or lower case by pressing
C to toggle the case.
EXTended baudot can change the case according to the received text,
however if fixed case mode, EXTF, is used or if noise causes the wrong
case to be selected the case can be changed with C.
EXT/EXTF Extended baudot (E, ALT-E, ALT-C ): 13
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Extended baudot allows the transmission and reception of the full ASCII
character set while retaining 100% compatibility with standard baudot
decoders. This allows a much wider range of punctuation characters as well
as allowing both upper and lower case. This achieved by using the BLANK
character, sometimes in combination with the other shifts, to select upper
or lower case, or to select alternative punctuation alphabets. Diddle
is still possible by simply repeating the current letters or figures shift
character (which is more robust anyway). BTL extended baudot for ASCII
characters is compatible with HAMCOMM extended baudot. BTL allows a further
extension which is not always 100% compatible with standard baudot, which
allows transmission and reception of the remaining PC character set, allowing
non-english characters, symbols etc. To ovoid incompatibilities when the
receiving station does not have BTL extended baudot, simply don't send
non-ASCII characters!
Automatic Extended baudot detection (E):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
BTL can automatically recognise an extended baudot transmission and decode it
accordingly if the auto EXTended baudot mode is active. (E). In this mode
EXT is displayed on the status line and is WHITE when BTL is decoding
in extended mode, and BLACK when decoding in standard baudot mode.
14
BTL will always detect true extended baudot, but may not always
immediately recognise standard baudot. This is not usually a problem,
however if it is you can toggle EXT mode off by pressing E again.
Forcing extended Baudot decoding (ALT-E):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noise can sometimes causes the auto detect mode to temporarily switch to
standard mode when extended baudot is being received. You can force
extended mode decoding with ALT-E. Forced EXT mode is shown in YELLOW.
Fixed case extended baudot decoding (ALT-C):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noise can also cause the case to jump between upper and lower case in
extended mode. This can be annoying, so you can prevent the case from
changing by pressing ALT-C. EXTF is displayed to indicate fixed case.
By using fixed case you can still decode extended punctuation without
having the annoying side effect of the case jumping up and down with noise.
In fact EXTF mode works well irrespective of what mode is sent.
In fixed case mode, the case may be changed by pressing C as described above.
RXR - Tone reversal mode (R): 15
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the station you are listening to has its Mark/Space tones reversed,
or if your receiver is not set to the same sideband mode as BTL (see below)
then RXR is a quick way of reversing the Mark/Space tones without having to
retune your receiver. RXR does not effect transmit. See 'sideband mode' below
Sideband selection (S):
~~~~~~~~~~~~~~~~~~~~~~~
The sideband you set your receiver to determines the which way around the
Mark and Space tones are (which one is high and which is low). Set the
sideband mode to tell BTL which way around to expect the tones to be.
You can still copy a signal if the sideband mode is wrong by using RXR.
Sideband mode determines the polarity of transmit tones. For USB MARK is HIGH
Forced Letters shift (SPACE) or Figures shift (F):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When receiving standard Baudot RTTY a FIG shift character can be receiver
in error due to noise. This changes the alphabet to numbers and punctuation
instead of letters, resulting in garbled copy of text. To force the alphabet
back to letters press SPACE. To force the alphabet to figures press F.
UNS - Unshift on space (U): 16
~~~~~~~~~~~~~~~~~~~~~~~~~~~
A useful automatic feature to overcome the above problem is to automatically
revert to letters mode on receiving a space character. This usually works
well, however there are some cases where numbers or punctuation are meant to
have a space between then, when this feature will force copy into letters
mode when numbers had been sent. If this is a problem UNS can be toggled off.
UNS also unshifts on Line-feed and Carriage-return.
LOG - The log file (L):
~~~~~~~~~~~~~~~~~~~~~~~
The received text can be logged in a file. You will be prompted for the file
name. The file will be opened in APPEND mode, adding to what is already in
the file. The log file may be closed again by pressing 'L' again. The log
file is automatically closed upon exit.
Display text mode - 43/50 line mode (D):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
EGA/VGA text screens are capable displaying of either 43 or 50 lines of text
respectively. To toggle this mode press 'E'
Hold (H): 17
~~~~~~~~~
Pauses demodulation temporarily. Press 'H' again to resume. Normally decoding
continues in the background, even when in the help or other screens.
New Line (enter) and Clear Screen (home):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Enter moves the cursor position to the beginning of the next line. Using HOLD
helps when inserting multiple new lines. Home clears the decode screen.
Transmit mode (T), ESC exits TX mode:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Press 'T' to enter the transmit mode. BTL starts with a short MARK tone
followed by a LF, CR, and Letters shift, then 'diddles' until a key is
pressed. There is no type ahead buffer, however words can be edited before
TX, as described below. Word wrapping and auto CR/LF are active at the end
of long lines. Each new line is indented on the screen with a '>'. This is
not transmitted. All transmitted text is written to the log file if the LOG
function is active. Refer to 'Transmit setup' on page 7.
ALT-X Stops transmission immediately, ESC waits until buffer transmitted
Word mode (ALT-W) (switchable during TX & RX) buffers characters in TX mode
until a word is completed, then transmits it. This allows BackSpace editing.
Function Key Text Buffers (F2-F12): 18
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Single lines of text may be stored in the Function Key Text Buffers and
transmitted by pressing the corresponding Function-key (F2-F12) during
transmit mode, or when a #Fn sequence is encountered in a Brag file.
These buffers may be edited in receive mode by pressing ALT-[Function key].
After editing, press ENTER or ESC to save the buffer. CTRL-ENTER inserts
a CR into the buffer without stopping the editing. CTRL-Z inserts an End Of
Transmission. The buffers are saved between sessions in the BTL.FNK file.
CTRL-HOME clears the buffer.
Brag files in TX mode (ALT-B):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Text files can be transmitted during TX mode by pressing ALT-B and typing
the file name without an extension. On the screen this will appear as: name
As soon as a SPACE or RETURN is typed this will be replaced by the
contents of the file NAME.BRG and the file will begin transmitting.
NAME can be any filename. One or two letter abbreviations are convenient.
BACKSPACE is active when typing in the filename. ESC cancels brag file
name entering. The sequence #! in a brag file indicates the End Of File (no
CR/LF), and #* indicates an End Of Transmission. ALT-X still immediately
aborts TX mode even when a text file is begin transmitted.
Function key text references in a Brag file: 19
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can include Function Key text in Brag messages by including the sequences
#F2 to #F9 for F2 to F9, #F0 for F10, and #FA and #FB for F11 and F12
The Function Key buffers are good for often changed text like the other
stations callsign, name and his signal report. These can then be included
in Brag files like "#F2 de MYCALL" and "Your RST is #F4" or "Good
evening, #F3" where F2 is his call, F3 is his name, and F4 is his report.
Default settings and the BTL Config file:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Many parameters are stored in the file BTL.CFG in the BTL program directory
upon exiting BTL. If this file does not exist BTL will create a new one.
The sideband mode, baudot standard (including EXTended baudot settings), text
mode, input selection and levels, baud rate, adjustable preset frequency and
shift, last selected preset shift and centre frequency, and the status of
UNS, NAR, and Word TX mode, are all saved in the CFG file.
Upon start up the centre frequency and shift are set to the last selected
preset values. One of these preset values is adjustable (page 11). RXR is set
off, so that the tones are the right way around for the selected sideband.
The I/O Control Panel (I) 20
~~~~~~~~~~~~~~~~~~~~~~~~~
ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ»
º I/O Control Panel º
º ~~~~~~~~~~~~~~~~~~~~ º
º Line In ßßßßßßßßßßßßßßßß º
º Mic ßßßßßßßßßßßßßßßß º
º Output ßßßßßßßßßßßßßßßß º
º AGC Auto Gain Ctrl º
º PTT COM2 º
ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ
The I/O Control Panel is used to select the input, and set the input
sensitivity, output level, AGC, and PTT COM port. SB PRO's can't adjust the
MIC level and AGC is always on. Audio levels are not adjustable on < SB Pro.
To select input: L = Line-In, M = Mic (>=SB pro)
To deselect input: L or M when field is highlighted (>=SB16 )
To highlight field: L, M, Output, PTT or / ARROWS. A = AGC toggle
To adjust field: / ARROWS adjust the highlighted field (White)
Return to Demod screen: ESC or ENTER
PTT signal is available on RTS pin of selected COM port - Hamcomm compatible.
RTTY, the Baudot Code, and Baudot Standard Selection (B): 21
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
RTTY stands for Radio Teletype. On an SSB receiver it sounds like a steady
'diddle' where a tone rapidly toggles between two similar frequencies. Other
digital transmissions heard on the air are mostly sent in bursts. These may
be AMTOR, PACTOR, PACKET, or some other mode.
A RTTY transmission sends a character as a stream of bits. A high bit is
represented by a MARK tone and a low bit is represented by a SPACE tone. Each
bit is a fixed length. These tones are different frequencies, a high radio
frequency for a MARK and a low radio frequency for a SPACE. If the receiver
is in USB mode the audio tones will be the same way around. If LSB is used
they will be reversed, ie MARK will be the lower audio tone. Use the Sideband
selection feature 'S' to tell BTL which way around to expect the tones.
Each Baudot character is made up of 7.5 bits. This is made up of 1 start
bit (SPACE), 5 data bits (LSB first), and at least 1.5 stop bits (MARK).
- Since Baudot is asynchronous the stop bit may be any length >1.5 bits. A
new character must have a MARK before it so the start bit can be detected.
The 5 data bits decode to one of two separate 'alphabets', one for letters
and one for numbers and punctuation. Special codewords are used to select
the alphabet, these are called Letters and Figures shifts. There are also
idle (blank), space, carriage return and line feed characters.
There are two different standard Baudot codes is common use, ITU2 and the
US standard. You can select either in BTL by pressing 'B' during reception.
Code Letters Figures Code Letters Figures LETS<->FIGS Table 22
00000 Blank Blank 00001 T 5 A - N , 1 Q % F
10000 E 3 10001 Z + " B ? O 9 2 W @ G
01000 LF LF 01001 L ) C : P 0 3 E # H
11000 A - 11001 W 2 D ¨ Q 1 4 R * J
00100 Space Space 00101 H # ++ E 3 R 4 5 T ( K
10100 S ' * 10101 Y 6 F % S ' 6 Y ) L
01100 I 8 01101 P 0 G @ T 5 7 U + Z
11100 U 7 11101 Q 1 H # U 7 8 I / X
00010 CR CR 00011 O 9 I 8 V = 9 O : C
10010 D ¨ $ 10011 B ? J * W 2 0 P = V
01010 R 4 01011 G @ & ++ K ( X / - A ? B
11010 J * ' 11011 FIG FIG L ) Y 6 ' S , N
00110 N , 00111 M . M . Z + ¨ D . M
10110 F % ! ++ 10111 X / Note the numbers are 'North
01110 C : 01111 V = ; west' of the qwerty keys on
11110 K ( 11111 LET LET the keyboard.
LSB of code shown first CR Carriage return. BTL performs a
* $ ' ! " & ; are the US characters. CR + LF when a CR is received.
¨ 'Who Are You?' request. LF Line feed, BTL displays LF as '\'
LET Letters shift if LF is not associated with a CR
FIG Figures shift ++ % # @ are not defined in ITU2
Extended Baudot: 23
~~~~~~~~~~~~~~~~
Extended Baudot as implemented in BTL follows the same standard as Hamcomm.
Extended Baudot allows transmission of the full ASCII character set using
the standard 5 bit baudot code, while still remaining 100% compatible
with standard decoders. There are many stations out there using Hamcomm
who already transmit Extended Baudot, so its nice to be able to decode them
properly, and also transmit to them using the full ASCII character set.
To achieve this miracle, we need to find lower case, and another 18
punctuation marks etc. (we have not included characters 0-31 except CR and
LF). The BLANK code is redundant in baudot, since either the FIG or LET
characters can be used to idle. So we can use BLANK as an extra shift.
In Letters mode, BLANK toggles the case between upper and lower. In Figures
mode, BLANK changes decoding to a second figures alphabet for the next
character only. By default when you exit FIGS mode returning to letters,
the case reverts to upper case, and must be toggled to lower case again if
required. To confuse matters the BLANK may come immediately before a FIG or
LET shift to denote either second FIGs (reverting to normal figs after one
char), or lower case when returning to letters mode.
BTL goes further and specifies 5 extra second figs chars as PC shifts which
reverts to letters after the next char. Each PC shift specifies a bank of 32
PC characters, including codes 0-31, and >=128, and takes 4 chars to send.
The GLORY page: 24
~~~~~~~~~~~~~~~
BTL was written to fill a huge hole in the current state of ham software, ie
a simple, free 'download and play' data modem using the SoundBlaster and PC.
This program is being released as free software for non-commercial and
non-government purposes in the spirit of Ham Radio to encourage people to
take the plunge into the fascinating world of digital radio with no need to
buy expensive data modems. And with no compromise in performance either. In
my tests BTL easily matches, and even exceeds the performance of my expensive
analogue modem.
In the next year or two I hope to take BTL even further. Unfortunatly
there won't be many more free releases, since this version achieves the aims
set out above. There will be some free additions and improvements though.
Later versions may include AMTOR, PACTOR, and perhaps some of the new high
performance DSP modes too. A TSR version is also planned for third party
terminals and contesting programs so you can use BTL like an external modem!
Who knows, maybe one day BTL will be a Windows program ..... dream on!
Of course all this takes time, effort and a lot of motivation! If you find
BTL useful, and would like to provide an incentive for further development
you can REGISTER your copy... read on!
REGISTRATION: 25
~~~~~~~~~~~~~
Registration is voluntary for this version. You can support the continuing
development of BTL and provide a considerable incentive for me to spend my
free time developing this program by REGISTERING. In return I can offer you
free technical support and free upgrades to all later versions of BTL which
may not otherwise be free. This offer is limited until the next version of
BTL is released, but may still be available. Check for the latest version.
Register by sending fan mail and a mere $US 30 or $NZ 40 to:
Robert Glassey, ZL2AKM
52 Bourne Crescent
Christchurch 8005
New Zealand
Email: robglassey@geocities.com
Try the BTL home page at http://www.geocities.com/SiliconValley/Heights/4477/
Or search http://www.qrz.com for ZL2AKM
Registration does not imply a warrantee of any kind.
COPYRIGHT: 26
~~~~~~~~~~
BTL Version 1.54c, 19/2/98
NOTE: V1.54c is a BETA release only and is not intended for distribution.
BTL is copyright (c) 1996,1997,1998 by Robert Glassey, all rights reserved.
This version of BTL is provided FREE, as is, without any warrantee of any
kind, for non-commercial and non-governmental purposes only.
Use of this version for commercial or governmental purposes is
expressly forbidden.
Distribution is permitted only in its original unmodified form for FREE
or normal and reasonable shareware distribution, net access, or CD ROM
charges.
(
geocities.com/siliconvalley/heights) (
geocities.com/siliconvalley)