The most common is running BTL under windows. If it doesn't work,
QUIT windows.
This is probably the most common problem. Fortunatly the problems are often easilly rectified.
The most common is running BTL under windows. If it doesn't work,
QUIT windows.
Check that the BLASTER enviroment variable is set correctly, and that
any drivers needed to set up your card are properly installed.
Some drivers are windows programs. You may need to run windows then
quit again before running BTL.
Some drivers may actually cause the problem, try taking them out.
You may have hardware conflicts. Try a different address, IRQ or DMA
parameter, depending upon the problem BTL reports. (setting up your
card to the same of course)
If you don't get any signal showing on the level indicator check the
Sound Blaster control pannel and the relevant help page. Ensure the input
is selected correctly, and the level controls are not turned down too far.
Many non-Creative Labs sound cards have their own propritry mixer chips.
If the audio input or output is not working properly, run the sound card's
own mixer configuration program. You may need to adjust levels there
or select the correct inputs and outputs etc.
Sound Blaster version numbers
1.x SB 1 compatible (8 bits mono)
2.x SB 2 compatible (8 bits mono)
3.x SB Pro compatible (8 bits stereo)
4.x SB 16 compatible (16 bits stereo)
Many non-Creative Labs 16 bit cards will report V3.x. This indicates
that the card does not support the full SB 16 mixer or 16 bit functions
and may use its own propietary method or some other standard. This is
generally not a problem as BTL only requires 8 bits anyway.
The input control pannel does not work for V1 or 2, since there are no
adjustable levels or selectable inputs.
Mic input level and AGC are not adjustable on SB V3.x
Do I really need a transformer for TX?
Possibly not, but in many cases you may need it, and in most cases it will help ensure your transmissions are clean and undistorted.
Just listen around the band, there are quite a number of fairly poor
quality signals out there, and most of these are due to the incorrect
use of AFSK. This is why many operators perfer not to use AFSK, using
the radio's FSK inputs instead. AFSK has gained a bad reputation
because of the problems that can arise and the poor signals that can
result. But AFSK needn't be bad. Ironically many radios actually
generate AFSK internally from their FSK input!
So what makes AFSK signals bad?
A noisy, non-sinusoidal, jittery or non-phase continous audio signal.
BTL generates clean, sinusoidal, phase continuous audio.
Over driving the audio input stage of the transmitter, generating audio
harmonics. Don't rely on turning down the MIC gain, this control may be
*after* the input amplifier. If your radio has a high level input, use
it, if not reduce the audio level before you put it into the MIC input!
The transformer helps here, although a resister attenuator may be needed.
Output levels from the SB pro and SB16 are adjustable from the Sound
blaster control pannel, but beware that low levels are more suseptible
to noise and envelope feedback (below). It's better to reduce the level
physically at the TX input with a series resistor and one to ground,
directly across the TX input terminals. Better still, use a transformer.
Feedback via earth loops. This is especially bad with DC powered
transmitters. A 100W transmitter can draw 20A from the DC supply,
and the current will to some extent follow the modulation envelope
of the transmitter. Some of this 20A will flow down every wire that
somehow makes its way back to your power supply, including any audio
ground between your PC and the transmitter. Since the ground wire
must have some resistance, the modulation envelope will appear as a
voltage across the ground wire. This adds to the audio signal, forming
a feedback path from the TX modulation back to the audio input, and if
the input gain or ground resistance is high enough, the whole system
can oscillate! And even if it doesn't oscillate, it can still cause
distortion of the audio. There are several cures:
- Use a thick ground between your PC and TX, but beware if the resistance
between the PC and the power supply ground is also small, you will just
end up putting more of that 20A through your PC ground, so you loose the
benifits you would have gained!
- use a very thick ground between your TX and the PSU, so most current
will go that way.
- Use the high level input on your transmitter, so input gain is less.
- Place the resistive audio attenuator as near to the TX input as possible
so the modulation feedback is on the high level side and is attenuated too.
- Break the ground between the PC and transmitter so no current can flow
along it, while still allowing the audio to pass, ie use the audio
transformer as an isolation transformer. Make sure the two halfs
of the audio ground are not directly connected together. It's ok if
the PC and TX ground are connected elsewhere, since voltage drops
along those grounds won't be added to the audio signal.
Audio transformers are cheap and easy to use. They're well worth it!
Computer generated noise and mains hum on the earth. Again this is
down to earth loops. An audio isolation transformer will help here
too.
PLEASE use some kind of RF filter on the audio cables when you transmit! Unless your antenna system is perfectly ballanced (which they never are) there WILL be some RF currents flowing around the ground wires in your shack. And those ground wires may happen to resonate at some fatal operating frequency, and you may just get high-ish RF voltages or currents being pumped straight into your PC, especially if you are using an non-resonant antenna like a G5RV. I blew up one soundcard like this, so please don't repeat my mistakes! Add small capacitors between the signal wire and ground on your audio leads, both TX and RX leads. This is described in the help.
Most PC's and sound cards are not designd to be connected to a 100W+ transmitter! - protect your investment.
OK, if you have a well installed station, with good, balanced, low SWR
antennas, solid earth bars and good earthing, the above may be overkill
but there are so many bad signals out there, please don't be one of them!
Sideband mode
This is a new concept to many RTTY operators. Most modems are configured to use either LSB (US standard) or USB (European standard). The transmit tones are set so that they appear the right way up when that sideband is used. If the received signal is upside down then most modems have a Receive Reverse function (RXR) to compensate, and probably also have a TX Reverse function or similar to allow you to reply upside down.
You can configure BTL to be either USB or LSB using the Sideband selection function. If you hear a signal that is upside down, BTL also has a RXR function. Of course RX Reverse only effects RX, so if you want to transmit upside-down, you must turn BTL upside-down, ie use the other sideband mode in BTL, and turn RXR off again.
Remember: If RXR is on, TX and RX will always be the opersite polarity.
Default tone sets
There are 4 preset centre frequencies and 5 preset shifts. One preset shift and one preset centre frequency are user definable (select white preset, adjust then press ALT-P).
BTL will always start up on one of these presets, ie the last preset selected. This is so if you tune off frequency slightly for one signal then exit, you will always be back on the standard tones when you restart.
You can also reset the tuning to the preset standards using the preset selection keys.
If the filters in your rig do not coinside with the predefined frequencies,
you can set up the user defineable preset to suit your rig or personal
preference.
US RTTY standards
BTL is set up by default to the European standards of USB, 1445Hz Mark, and 1275 Hz Space (1360 centre), using the Extended Baudot alphabet which is ITU2 compatible.
You can change these for the US standards by selecting LSB mode, and a centre frequency of 2210Hz (2295Hz Space, 2125Hz Mark). You can select the US standard Baudot code by pressing B. These settings will be saved automatically in the BTL.CFG file and will be the defaults next time BTL starts up.
You can easilly switch back to Extended Baudot or USB with a single key press.
Brag files and Function key buffers
Brag files and function key buffers are quite different beasts. Function key buffers are single lines of text, editable on-line, which can be transmitted by the press of the function key, or by including #Fn in a brag file.
Brag files may be multi or single line text files, edited off line, with commonly used phases, station descriptions, abreviations for long words, variations on a theme (ie name or call sent once or repeated several times), etc.
You can include function key buffers in brag files, which allows 'personalised' brag files for the station you are working, eg "#F2 de G0VTQ, #F4 #F5, name here is Rob, UR RST #F6" Where F2 is his call, F4 is good morning or good afternoon etc, F5 is his name or OM if you dont know yet, etc.
To transmit a brag file press ALT-B and type the brag file name without an extention then press SPACE or ENTER and continue typing.
Function key buffers are good for storing often changed text like the other stations callsign and name, his signal report, and maybe todays 'news' or weather at your location. They can also be used as type ahead buffers so you can type a reply in one or more function key buffer while receiving, then transmit it in your over with a single function key press.
You may find it convenient to set F3 to "de YOURCALL" so the sequence F2 F3 is "HISCALL de YOURCALL" or you may prefer to set up a brag file so the sequence ALT-B B is #F2 de YOURCALL.
Instead of typing "My QTH is XYZ XYZ XYZ" you could just type ALT-B Q and continue typing. Brag files needn't be long, you can simply abreviate a long word to save the typing!
Because filenames are used, the number of brag files is virtually unlimited,
and they may be as small or large as you like. You can have a different
file for different times of the day, or varying numbers of repeats. You
can specialise brag files just by haveing multiple copies with only a few
differences, like wxfine.brg, wxrain.brg, wxsnow.brg, etc, you could
even put the current temprature in a function key buffer, or the whole WX
report for that matter.
End of File, #! and End of Transmission, #* or CTRL-Z
You can place a #! in a Brag file to indicate the end of the file ovoiding CR LF's.
You can place a #* in a Brag file to indicate the end of transmission. BTL will transmit all charactors up untill this mark then end the transmission.
A CTRL-Z charactor in a Function Key Buffer will also end the transmission.
I hope that covers most things. Enjoy BTL!
73's
Rob Glassey, G0VTQ