Blaster TeLetype Home Page

Hi Everyone, welcome to my home page.

This page is continuously being updated. Last updated 11-Nov-98

Welcome, visitor number (since Dec 28, 1997 - my old counter got messed up)

What's on this Site?

Rob's Back! 8-Feb-98
with a new address and callsign. 8-Feb-98
Text version of on-line help is now available 16-July-98
BTL V1.51 is Here!
Download BTL151.ZIP
PTT and bug fix available in BTL V1.54 11-Nov-98
Download BTL154e.ZIP 11-Nov-98
What is Blaster TeLetype?
BTL V1.51 Features
BTL FAQ and trouble shooting guide
BTL Change history
Questions and contacting me 3-Jan-98
The BitBucket mail reflector
What's planned for BTL V2.0? 8-Jan-98
What is BTL-TSR?
How about Registering? 8-Feb-98
Coherent CW 19-Apr-99
Who is Rob Glassey anyway? 8-Feb-98

Links to other sites

The Human readable visual text modes page is dedicated to Hellschreiber and all its modern derivatives. This is a mode experiencing a small resurgence amongst keen HF digital mode experimenters with the aid of modern computers and DSP. FREE sound blaster software is available to download so you can have a go yourself! 13-Aug-98

This site is a member of the Amateur Radio Webring link exchange

The Worldwide Utility News Club (WUN) is devoted to the exchange of information about HF utility stations such as Weather, News, Diplomatic services etc. WUN maintains various FREQUENCY LISTS, including a CD ROM, and publishes a monthly newsletter.

NoBARC, North Berkshire Amateur Radio Club,Massachusetts USA. (Their Links Page is from K1DWU.NET) 13-Sep-98
Mario Bartuccio, IT9JPK, has a link to this site. Visit his Home Page
Visit Noriaki (Nori, JA1WSK) Katsumi's Home Page
OH2GI Ham system contesting program Home Page
OH2GI Ham system review
The Sun and propagation info
Wholesale Drainage - My brothers rock band, with sound samples
My Soundblaster and Digital radio Resource Page
Sound Blaster programs for Ham Radio
RTTY Loop columns
Jim's Gazette (Ham radio)
Ham Radio On-line magazine
WM7D's Ham Radio site 3000 excellent ham links checked twice a week!
The G7KPF UK Amateur Radio Quick Links page has a link to this site. Find UK Ham pages by callsign FAST.
K1DWU.NET Ham site with 2500+ Ham radio links and much more ham radio information. 13-Sep-98
N1RCT's RTTY homepage 13-Sep-98
QSL.NET Ham radio site 13-Sep-98


8 February 1998

Yes everyone, I'm back after 6 months of intensive R&R, and 3 1/2 years overseas. Sorry to all those of you who have mailed me while I've been away, since my replies have been somewhat slow, as expected.

Finally I have got myself set up in a new QTH and back on the net again. I've also got a new call, ZL2AKM. Life is now returning to some sort of normality again so I can start working on BTL once more. Thanks everyone for bearing with me while I've been away.

I hope that while I've been away many people have had the chance to download BTL 1.51 and try it out. I hope you all like it! I've received a number of suggestions for the next version, most of which are included in What's planned for BTL V2.0?

So now I'm back those emails can start flooding in again (not that they ever stopped completely), and while you're at it how about considering registering your support for BTL? There's nothing like a little financial incentive to keep the wheels of industry spinning! There's other advantages too! Register right now via email!

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BTL V1.51 is Here

Download BTL151.ZIP

Download it and try it out! (64K) I think you'll like it! This really is the final release version! This release contains a README.TXT file, CHANGES.TXT, and a FAQ and trouble shooting guide, plus a number of example Brag files.

Other changes from V1.5 are:

ALT-X now always stops Brag file transmission even if other characters have been pressed during brag file transmission.
Help text updated to include Baudot standard selection key.

I hope you all enjoy using BTL as much as I have enjoyed writing it. Many, many thanks to all those folks out there who have tried BTL and given me feedback. Your tests, comments and enthusiastic support for BTL has made it what it is today! I hope BTL is now a stable, robust, widely compatible and user friendly program that will encourage many many people to take up digital modes and experience the thrill of operating a new mode. Now any radio amateur with a PC, sound card and transceiver can be on air with RTTY in minutes, for FREE! (BTL is great for listeners too!)

V1.51 released 27-Aug-97

Change history

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BTL V1.54e is Available Now

Download BTL154e.ZIP

BTL V1.54e is a beta release containing a few small changes, bug fixes, and a PTT output. These features have now been proved in beta testing.

New Feature - PTT

A PTT signal is now available on the RTS pin of a select COM port (COM1-COM4). This signal is active HIGH and is HAMCOMM compatible, ie you can use existing HAMCOMM interface units to key your TX.

This has been one of the most popular requested features, as many people are unable to use the VOX. PTT may be used to key Linear Amps, transmitters without VOX, or in the rare situation when non-standard sound cards feed received audio back to the sound card output.

The COM port is selectable through the "I/O control panel", by pressing 'I' in receive mode. Select PTT and use the arrow keys to select the COM port. PTT may be disabled by selecting NONE for the COM port. (the I/O control panel was formally called the Sound Blaster control panel)

Bug Fix

Bug Symptoms:
Flickering of level and tuning indicators between 0 and correct level every half second.
"PC too slow" errors on 386's and low end 486's, which should be able to run BTL OK.

This bug depends upon where a buffer resides in memory, and can potentially effect one in 16 PC's.

Bug work around: Remove or add at least 4Kb of TSR's, thus moving the position of the buffer in memory.

V1.54e should cure this bug.

BTL -nomixer option

Some sound cards have problem with non-standard mixer configurations. BTL is often not able to set the mixer correctly on these cards (input & output selections and levels).

To help solve this problem a command line option has been added to BTL to disable mixer control by BTL. This allows you to use third party mixer control programs to select inputs and set levels and the AGC.

To use this options start BTL with the -nomixer option:

BTL -nomixer

Often a DOS or Windows based mixer program is included with your sound card and may be installed with your card or may be installed or executed later. Use this to select the correct input and set the input and WAV/DAC output levels and master volume to maximum. Then run BTL -nomixer

WIN95 users can use the WIN95 volume controls, normally these are shown as a speaker on the far right of the task bar. Double left click on this. This should bring up the output selections and levels. To set the input levels, select Options - Properties - Recording. AGC is an 'Advanced option', first select Advanced options from the options menu, then press the Advanced button on the recording pannel. You should be able to run the mixer and BTL (full screen in a DOS box) together and see the effect of volume changes immediatly while BTL is still running.

Other Changes

IRQ9 is allowed
Output level on SB16 can be adjusted in finer steps and allows a higher maximum output.

V1.54e released 11-Nov-98

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Blaster TeLetype

Finally, Blaster TeLetype V1.51 is available Here!

Blaster TeLetype (BTL) uses the Soundblaster card and a 386DX or better to receive and transmit radio teletype (RTTY). RTTY is used by radio amateurs and many others to transmit text messages, news, conversations, weather reports etc around the world. BTL uses DSP techniques to give demodulation performance exceeding that of most analogue RTTY modems.

RTTY is one of the simplest forms for data communications over radio, and has been around for something like 50 years. Modern data modes are error resistant and can go much faster over the 10's of thousands of kilometers amateur radio operators regularly communicate over. However RTTY is probably the most popular data mode used by amateurs, mostly because it is simple and very widespread, so there's lots of activity.

However this simplicity does not mean high performance is not possible, far from it! BTL can print readable text when the signal is barely audible amongst the background noise. SNR = -5 dB in a 3kHz bandwidth.

For amateur RTTY listen around 14.085, 21.085, 3.585, and 7.035 MHz, SSB.

BTL is FREE for amateur use. But voluntary registration is encouraged to support the ongoing development of this program into a fully featured DSP multimode modem using only a PC and sound card.

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High performance RTTY Reception and Transmission using a Sound Blaster compatible sound card.
Function key TX buffers with on-line editing while receiving simultaneously.
Text file transmission, with the ability to include function key text, End of file, and End of transmission sequences.
Word buffering during TX, allowing backspace editing during live transmissions.
On screen tuning and level indicators.
Fully adjustable centre frequency and shift, with selectable preset standards.
User definable preset shift and centre frequency.
Fully adjustable baud rate, 25 to 200 Baud.
USB or LSB default Mark/Space polarity for receive and transmit.
RXR Mark/Space tone reversal on receive
Narrow/Wide tone filter option
Unshift on Space (UNS)
Selectable US or ITU2 Baudot standards
Extended Baudot, HAMCOMM compatible
All printable ASCII characters available with Extended Baudot
Fixed case option for Extended Baudot decoding
Upper or lower case toggle for received text
Received and transmitted text logging to a file
43/50 line mode selectable
Manually forced letters or figures shift during RX
Manually forced New Line and Clear Screen on demodulation screen
Demodulation pause key (Hold)
Adjustable input sensitivity and output levels
MIC AGC toggle and input selection
Function states and settings saved between sessions
Support for Sound Blasters version 1.0 through AWE32
Compatible with most Sound Blaster compatible cards
Sound Blaster parameter validation
On-Line HELP!!!
Bright Colours!

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Questions and Contacting the Author

If you experience problems with BTL, please read the on-line help first. Often the necessary info is there. I've also prepared a trouble shooting guide.

Now I've returned from my travels I will be around to answer questions and open fan mail! :-) Most letters I receive fall into one of these categories:

1. Sound card problems
2. Suggestions for new features
3. Fan mail :-)
4. Others

Persistent sound card problems are often due to non-compatible cards or non-standard mixers on "compatible" cards. Look at the On-line Help and trouble shooting guide first, since most problems are covered there. Some cards may need their non-standard mixer settings to be set manually to get BTL to work. Unfortunately some non-standard cards just don't cooperate (very few) - Try another card! Virtually any cheap SB compatible will work.

Please let me know if you still experience this problem after having exhausted all the more common solutions in the help etc, so that I can gauge the extent of this problem and maybe spot a pattern.

Suggestions are always welcome. Check the new features list to see what's coming up. If something's not there, or there's something you'd like to comment on, or even if you'd just like to add your support for any particular feature, let me know!

Fan mail is always welcome :-)

Other problems seem to be few and far between, or at least covered adequately by the on-line help or trouble shooting guide. Many people have commented on how easy BTL was to get running on their PC. But if you have any other problems please let me know, especially any bug reports.

Registered users of BTL always take priority and special features or bug fixes can sometimes be added on request and emailed back to the registered user very quickly. Registered users can sometimes get Beta test versions with new features long before these features are officially released or beta tested.

For discussion groups relating to BTL try either the NEWS group, or the BitBucket mailing list.

To subscribe to the BitBucket, send email to with body of message containing the following:


BitBucket is a mailing list (reflector) devoted to specialised amateur radio communication techniques.

Packet, Pactor, GTOR, Clover, AMTOR, RTTY
R/C, Telemetry, Balloons, Rockets, Robotics
homebrew, modifications, interfacing, widgets, etc

New Address

I have recently moved back to New Zealand. My new postal address for correspondence and registration is:

Rob Glassey, ZL2AKM
52 Bourne Crescent
Christchurch 8005
New Zealand

Any letters sent to the old address shown in BTL V 1.51 will still be forwarded to me but may take some time to reach me.

You can still send questions and comments relating to BTL to me at

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BTL 2.0

Well, most of the features promised for 2.0 are now in V1.5, although there are still many improvements I would like to make, as well as many new features. V2.0 is now scheduled for early 1998. Here's a few things that might be included:

Improved brag file and function key functionality
Improved on-line editing of buffers, incorporating brag files
Improved type ahead buffers
Improved buffer nesting
A simple contesting mode (serial number generators, formatted logging, dup. checking)
Rolling transmitted character display (?)
New FTT tuning indicator
PTT signal on COM port (Beta test available now!)
An ASCII mode
Auto fine tuning (?)
Even better sensitivity and QRM rejection

And all this will probably be free!!

But unfortunately this is probably where the freebies will end. There's still a lot more I'd like to add, but due to the amount work required, and licences needed for PACTOR, further development will rely on user support. If you'd like to see BTL go even further, please consider registering!

In future versions I hope to include AMTOR, PACTOR, and maybe a few of the newer modes as well. I also hope to add synchronous decoding, error correction on repeated text, optimal channel combining (an advanced form of threshold correction), plus improved sensitivity and QRM resistance. There may be a 100% compatible form of FEC RTTY in the pipeline as well!

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I'm currently developing a TSR version of BTL, called BTL-TSR.
BTL-TSR will allow third party terminal or contesting programs running under DOS to use the Blaster TeLetype Sound Blaster DSP modem for both RX and TX, via a virtual COM port.

BTL-TSR is NOT a pop-up version of BTL, it is a background program that looks like an external modem to any terminal program that may use it. BTL-TSR will be sold as a add-on or packaged with third party software.

BTL-TSR will allow you to use compatible third party terminal programs, combining the flexibility of third party terminal programs with the performance and convince of BTL.

BTL-TSR is also a considerable advantage when combined with a serious contesting program like OH2GI HAM SYSTEM, giving the operator DUAL MODEM operation. This is very useful for several reasons.
You have twice the chance of decoding the signal correctly (mainly due to the asynchronous nature of RTTY where sync is easily lost)
You can operate two transceivers simultaneously, or monitor one frequency while operating on another.
The almost single key press exchanges leave the operator with time to deal with two transceivers at once!

BTL-TSR will allow SSB/CW contesters to try RTTY contests with minimum outlay.

BBS software will be able to run without a dedicated modem.

When the higher speed modes are implemented third party multimedia software can be used.

If you would like your favourite terminal or contesting software to support the BTL-TSR Sound Blaster modem, then contact the author of your software and tell him about BTL-TSR, and give him this URL!

If you write such a terminal or contesting program and would like to add BTL-TSR Sound Blaster support then contact me !

Beta versions of BTL-TSR have been tested with OH2GI HAM SYSTEM and use in contests, but there is still plenty of work to do here. Development is continuing and first releases should also be available early 1998.

OH2GI HAM SYSTEM is reviewed at

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Rob Glassey, G0VTQ.

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