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Audio and Fast Data over HF SSB

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WinDRM Releases

windrm-23-jul-08 Download WinDRM version 4.2: ( )

Weekend AOR Digital Voice Net will is QRV every Saturday / Sunday - Summer 2:00PM EDT, 1800 UTC, Winter 2:00PM EST, 1900 UTC - 14.236 QRG USB. WinDRM / FDMDV Digital Voice Net follows at 3:00PM EDT, 1900 UTC , Winter 3:00PM EST 2000 UTC - 14.236 QRG USB.

WinDRM Utilities

WinDRM Docs V1r3 ( ) - WinDRM Usage Documentation

WinDRM_QuickSetupV1r1.pdf ( ) - WinDRM Quick Setup Documentation

tune.wav, g.wav, b.wav ( ) - .WAV files required for TUNE, G and B buttons. Extract into same directory as windrm.exe. Download and install only if you are a new WinDRM user - you do NOT need to download a new copy if you already have WinDRM installed.

Please join the new digitalvoice Mailing List for release announcements, upgrades and help using WinDRM.
New releases are announced to the mailing list first and this page is updated afterwards as soon as I can.

Notes about the 19-Mar-06 version release-notes.txt:

WinDRM 19-Mar-06 Release

Progress of transmit Lead-In and segments now shown as a percentage in
the Info box during transmit of pics (TX Pic). When a BSR request is
being transmitted, "BSR" will appear in the Codec box. Up to 7 sound
cards including Virtual Audio Cables (VAC) are now recognized.  Receive
audio (decoded voice) may be recorded by checking "Save audio" under the
Setup>Codec>.  While Save Audio is checked, the audio is recorded and
saved as a mlp file (audio.mlp) in the WInDRM directory.  Convert
mlp file to wav with Cesco's "Audio Convert" utility found at . Install  this utility in the WinDRM
directory with the mlp file.  The utility will playback the audio and
create a wave file (audio.wav) for playback on any wave player.  Note:
This release adds the ability to play the G, B and ID wave files in all
sound cards (previous releases allowed only the first card to play these
files).  However, with this change, these wave files must now have a
sample rate of 48,000.  Audacity (a free open source audio editor) may be
used for this conversion found at

Notes about the 3-Nov-05 version release-notes.txt:

WinDRM 3-Nov-05 Release

The main changes were:  Added "Spacebar PTT".  WinDRM may now be started
by pressing the spacebar when the TX Pic or TX Voice button is in focus.
A second push on spacebar returns WinDRM to receive.  Note: This feature
is active while either TX Pic or TX Voice button is in focus.  Press "tab"
on the keyboard to disable (un-focus).

Under Setup>Display:  Added "Flicker reduced waterfall" for laptop and
possible other fast LCD type displays and "Static waterfall" was renamed
to "Waterfall".

Notes about the 25-Oct-05 version release-notes.txt:

WinDRM 25-Oct-05 Release
Notes updated 25-Oct-05 by K0PFX, K9FB, N1SU

This version incorporates the new audio protocol.  Tests seem to show
that increased bitrates (Mode A, 64QAM, MSC Low Protection, or just click
the Speed button and select 64QAM) yield better audio quality approaching
the quality of the AOR modems.

Under PTT port you will see new options for "PTT on CTS" and "PTT on DSR".
The CTS and DSR inputs are used for remote keying of digital voice
transmissions, not image transmissions.  By connecting an active high
signal from your microphone PTT to the CTS or DSR line, you can key and
unkey your voice transmissions from the microphone switch or a foot switch
without using the on-screen "Voice TX" button.  It's very convenient.

Currently the CTS/DSR options are "reversed" and fixed using a null modem
cable.  This behavior is expected to change in the next release so that a
standard cable can be used without any troubles.

Also changed are the TX defaults (2.3 to 2.5 and Mode B to A).

Notes about the 17-Apr-05 version release-notes.txt:

WinDRM 17-Apr-05 10:25 Release
Notes updated 17-Apr-05 by N1SU

This version corrects a small bug relating to selecting Mode E.

ARQ does not work in nets, only station to station.  Use BSR for "ARQ"
functionality in nets.

Notes about the 18-Mar-05 version release-notes.txt:

WinDRM 18-Mar-05 18:06 Release
Notes updated 18-Mar-05 by N1SU

This new version provides the capability to stack BSR requests and


-stn a sends pic
-stn c receives with error, presses BSR
-stn b sends pic
-stn c receives with error, presses BSR
-stn a sends another pic
-stn c receives with error, presses BSR

-stn c has 3 BSR windows open now, and sends them one after the other.
-stn a will have 2 BSR request windows open now, and sends them one after
the other.
-stn b will have 1 BSR request window open, and sends it.

-stn c gets everything corrected.

Notes about the 24-Feb-05 version release-notes.txt:

WinDRM 24-Feb-05 20:18 Release
Notes updated 24-Feb-05 by N1SU

24-Feb-05 20:18 New replay button to replay last sent file

Notes about the 19-Feb-05 version release-notes.txt:

WinDRM 19-Feb-05 18:06 Release
Notes updated 19-Feb-05 by N1SU

19-Feb-05 18:06 New QAM-4 option for use during poor band conditions

Use of QAM-4 produces a robust waveform that is more tolerant of QRM and
other noise.  Transfer rates are approximately 40% slower using the
default options with QAM-4, however the reduction in speed can be
mitigated by using the "Speed" options for QAM-4 - click the Speed button,
then QAM-4.  This will set Mode A DRM waveform - MSC protection option has
no effect for QAM-4.  Mode A is preferable for use under all circumstances
except when band conditions are suffering.

Notes about the 3-Feb-05 version release-notes.txt:

WinDRM 3-Feb-05 14:26 Release
Notes updated 4-Feb-05 by N1SU

3-Feb-05 14:26 Increased filebuffer size and improved BSR operation

The TUNE.WAV file is separate from the regular install to save space.
You will need to download and install it only if you have never used
WinDRM before.  Download and uncompress
the file into the same directory as where you installed WinDRM.

New Features:

The Picture RX now has a filebuffer of 5 elements. It should remember
the segments of the last 5 received files.

-you receive file1.jpg, but only 100 out of 200 segments.
-you receive file2.jpg
-you receive file3.jpg
-you receive file1.jpg again. WinDRM will have part of file1.jpg in its
 filebuffer and complete the file on the next pass.

The advantage of multiple transmissions is not cancelled if you
receive a file "in between".

BSR does work very well in a 2 station qso. We have been able to 
transfer 50kb files in conditions where only 30% of the data is decoded.

BSR is difficult to handle in multi-station qso's. the bsr button 
must be pressed before the rx is locking to another signal.

-you do receive file1.jpg, but only 100 out of 200 segments.
-now, you have immediatly to press BSR, but not yes.
-another station sends file2.jpg.
-when freq is clear, you press yes on the BSR messagebox and send.

Received files/pictures are saved in "pictures" directory.

Filenames up to 80 characters are supported

8 COM ports are supported

23-Jan-05 13:15 Notes

Waterfall color changed to blue hues.

TUNE.WAV file is sent when TUNE button pressed - the TUNE.WAV file
included in the .zip file is calibrated for optimal level outputs for
adjusting microphone gain and tuning an amplifier.  Adjust your microphone
gain so that ALC is eliminated while the TUNE tones are heard.  Do not
adjust microphone gain after adjustments are made.  NO speech processing
should be used with WinDRM and or ALC action should be seen.  TUNE only
needs to be used when you change output power, microphone gain or turn
on your linear amplifier.  Close attention to tuning with a linear
amplifier is required or SNR will suffer greatly.

ID.WAV file is sent when ID button pressed - this feature is for sending a
"vanity" waveform similar to other programs that send a text "image" into
the waterfall.


BSR -- Bad Segment Report -- creates "rx_report.txt" in windrm directory.  
Reports what segments are missing after receiving a data transfer.

SPA -- Show Pic Anyway -- shows what is in the picture memory, complete or
not, intended for use when receiving an image file when some parts are
missing, jp2 files for example.

Only errored file transfers will produce a result from the BSR or SPA
buttons.  Any files received correctly will not produce output for BSR or

ID --  Play ID.WAV file, must be present in the windrm directory.  The 
file should be 48KHz sample rate or problems may occur.

DRM RX Settings window:

Frequency Acquisition Sensitivity:
Higher values: Will produce false locks on good signals, delaying decode.

Lower values: Will eventually not lock on "difficult" signals.

Sequence: Freq. lock -> Timing Lock -> FAC decode -> MSC decode

Freq. Acq. is searching for the 3 frequency pilots (tuning tones, also shown
in red areas of waterfall line). It compares the tuning tone amplitude to
the surrounding audio signal.

Info Box on main screen:

On TX:

File # / % of file sent

File #0 is the LEAD IN (first segments of file + last segment)

"Lead-in" is sent to allow RX synchronization before actual data starts.  
Lead-in is always present; lead-in length may be configured "Long" in
TX Pic (recommended).

On RX:

Segments "we know about" / segments sucessfully decoded

"we know about" segment count is unknown until last segment arrives.

On RX Voice:

% of sucessfully decoded frames (400ms) in last 60 seconds

Tips about data transfer:

WinDRM creates a unique transport ID to each data transfer based upon the
file being sent.  If a file is not received on the first transmission, the
sending station can send the file again (typically with 1 instance) and
the receiving station will be able to recover the lost frames.  This only
works if the same file is received by the receiving station and no new
data transfers sent.  Any new transfers (different transport ID) will
clear the picture memory and the transfer process must be repeated from
the beginning.  If you do not receive the file on the first transmission,
ask the sending station to resend a single instance of the file before
receiving any new files.

Please join the digitalvoice mailing list at
for future announcements, upgrades and help using the software.

Please join the new digitalvoice Mailing List for release announcements, upgrades and help using WinDRM.

New releases are announced to the mailing list first and this page is updated afterwards as soon as I can.

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