Digital Modes in EmComm

Report
WELCOM TO ARES® TRAINING
Class Participation
 Some information here may be basic to some of you but totally
unknown by others in the class. For the purpose of this class we
will assume you know very little about operating digital modes.
 We want class participation. Ask questions when they come to
your mind. If you know something I don’t then share it with the
class. We can all learn together.
 This is not a sink or swim class. If you need to know how to
swim you should be told the basics before getting into the water.
Here are the basics of the digital modes and NBEMS. So bear
with us as we tell you the basics and at the end of the
presentation we will get into the water.
Today’s Topics
What do we need to know to run a digital
sound card mode?
 How to connect the computer and sound card to the radio.
 How to set up the sound card levels.
 What software to use.
 How to configure the software for the mode.
 What mode to use and under what conditions.
 How to get the message into the software to send it,
Including editing the text message or image to a proper
size and format that can be sent.
 How to receive a message and format it for presentation to the person the
message was intended for.
Established Digital Modes by
Georgia ARES Section.
 Georgia ARES has three established and recommended
digital modes of operation at the present time, a fourth
may be added soon:
 Georgia ARES website now has a new digital page
outlining the these modes at http://gaares.org/digital
The Three Ga. ARES Digital
Operational Modes:
 NBEMS … a Sound Card Mode using FLDIGI / FLMSG
*Main subject for today’s class and demonstration.
*Can send messages and files to someone even when the other party is not at
their station.
*Many modes within NBEMS to use depending on propagation and
band. PSK
MT63
Olivia
 WL2K (Email over Radio)
*Can be used with TNC or a sound card mode /RMS Express /winmore software.
*Peer to Peer (simplex) or over WL2K Network.
 D-STAR / D-RATS
*Can be used via the internet or peer to peer simplex.
*Can send regular text or ICS forms and attachments.
*Can send and pull files from someone else’s computer when the
other party is not at their station.
*No external sound card interface, everything handled internal in the radio with one single cable
from radio to the computer.
*Can set-up reflectors accessed via RF or the internet including private message screens.
Why do we need Digital Modes and
what can we do with it?
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Sending data and binary files (Text and Images)
Sending long Lists of information
Lists of medications / patients
Information needs to be error Free (Error Correction)
Can be sent on separate frequency from voice net
When attachments need to be sent
Can send to any email address (WL2K)
Low cost Hardware or no hardware in some cases
Can relay digital messages without a computer or
interface using a cheap digital recorder.
Try Sending this by Voice !!!!!

What other
digital modes
would you
think we as
Amateur
Radio
EmComm
Operators
might use.
Slow Scan TV (SSTV)
 EasyPal and Windrm
*Digital SSTV?
*EasyPal and Windrm: Not really SSTV, the
SSTV part has stuck because they send images.
In basic terms it's file transfer also known as
DRM "digital Radio Mondiale" The advantage
over analogue SSTV is the error correction.
With error correction you can get a perfect
image IE what is sent is what you receive.
Two such programs are EasyPal and Windrm
and will use the same basic interface that you
may already be using for analogue SSTV.
Why might we need these image modes
such as EasyPal, SSTV or Windrm?
 Damage assessment images.
 Image of actual hand written prescription needs to be
sent.
 The message was given to you in image form to send.
NBEMS
Narrow Band
Emergency
Messaging
System.
WHAT IS IT?
 NBEMS is a system made up
of software programs working
together seamlessly to send
and receive digital data using
a sound card mode.
What are these software programs?
 FLDIGI / Sound Card Modem Program/ this is the
work horse of the NBEMS software suit.
 FLMSG / Message Handling Program/ This is the
Message interface of the NBEMS software suit.
 FLWRAP/ Error Correction verification program
(Needed on rare occasions)
NBEMS / FLDIGI DEMO
How do we connect up to make all this
work? Hard Connection vs Acoustic
Coupling
 Hard connection includes a physical Sound Card interface
connected between the Radio and a computer. (Example:
Signalink USB)
 Soft connection (Acoustic Coupling) would be simply
placing your radio speaker/mike next to your computer
speaker/mike to receive and send the digital sound.
 Acoustic Coupling works best on FM and using MT63-2000
Mode. This is not the ideal way but does work when no
interface is available and the message must go out.
What Sound Card Modes to use?
 Olivia 8/500 for HF (good for week and noisy signals
but slow).
 MT63-2k for VHF (fast and reliable on FM simplex or
through repeaters.
 PSK-125 HF or VHF not as reliable with noisy signal
but faster on HF than Olivia.
How do we get the information
that we need to send into
the software to send it?
 Type it directly into the modem software (FLDIGI) and
send.
 Type it into the message / forms software (FLMSG)
and send.
 Send it as an attachment in FLMSG that can be
handled by the software such as an Excel CSV file.
 Send an image file as an attachment in FLMSG or as a
binary image file in the appropriate software such as
EasyPal or Windrm or even SSTV.
What is the limit of the file size
that can be sent.
 Depends of the software and mode you are using to
send it.
 Depends if it is binary or text.
 Using NBEMS and generally speaking try to keep data/
text file sizes under 6k in size if possible. Binary files
(images) 4k or smaller if possible.
 If sending images, using software specifically designed
to send binary (image) files you can send an image of
up to 30k reasonably fast. (EasyPal or Windrm)
NBEMS Sending Time by Mode
Benchmarks Discussion
Compression and PSK don't play well together!
For 2K file, compressed file takes longer to
transfer with PSK modes.
6K file transfer is not appreciably faster with PSK
Reason is varicode
Varicode is optimized for “normal” text
Example – “e” = 11, “q” = 110111111
Compressed data no longer has normal
distribution of characters
Compression Conclusion
At first glance, compression sounded like a good idea
but...
Doesn't work well with PSK
Can't compress a small file very much
Potential to lose entire transmission if single bit is
dropped
Conclusion: Compression not worth the trouble most
of the time
What if the image file is too large
to send?
 Use image editing software to reduce the size of the image file.
HOW
 Save file in smaller format ex: save BMP or GIF to JPG.
 Decrease color depth or change to B&W if color is not absolutely
needed.
 Crop unneeded margins in image.
 Reduce actual size of image, it can be blown back up if needed on the
receiving end.
 Example of good free software to do this is Irfanview.
http://www.irfanview.com/
 Example of how to reduce the size of an image file in Irfanview.
What if the text file is too large to
send?
 Break the file up into two or three separate
transmissions. The receiving station can paste them
back together.
 Send them in a faster mode if propagation and signal
reception permits.
 Convert .doc and highly formatted files to .rtf or .txt
files.
 Compress files over 6k in size if using MT63-2k or a
mode that likes compression (not PSK).
Communicate with your served agency as to
what you can do and what you will need
from them to send their messages.
 The served agency needs to know how to get the message
to you and in what form.
 How will you as the operator get digital files from the
served agency to send.
 How will you present a received message to the served
agency? Is a printer available for you to network to? Do
you need to give them the message on a usb drive for them
to print? Do you have your own printer? Do you have
internal email access to send and receive messages from the
served agency?
 Sit down before hand and work out these details with your
served agency. Don’t wait until the incident and find out
you have no way to share sent and received messages.
Considerations that will mean
failure not to mention embarrassment.
 Did you practice, practice, practice using digital modes. (Use it or loose it)
 Don’t wait on others to train you. Practice at home.
 If you are sending through a repeater, is the time-out on the repeater set to allow
maximum duty cycle. Digital Data messages are longer than average voice messages.
 Tones on repeaters should be turned off during drills and emergencies.
 Do you know the lowest power level you can use to send a data message to your net
control or other stations from your assigned location.
 Is all the software you need loaded and ready to go on your computer and do you know
how to use it. Including text and image editing software. (Excel, Adobe Reader, FLDIGI,
FLMSG, FLWRAP, Irfanview and a text editor of your choice) These should all be part of
your GO-Kit and on your check list.
 Are your basic computer skills where they need to be? If not, learn them or take some
classes. No need to be a computer Guru, just the basics.
Pierce County ARES Training Site:
http://www.piercecountyares.org/nbems
Don’t forget to Calibrate your
sound card.
 Your soundcard’s clock rate needs to be checked and adjusted in
the modem software (FLDIGI) if necessary to calibrate the clock
rate to the sampling rate. (if you don’t understand this, never
mind, just use CheckSR software to find the number you need to
inter into FLDIGI.
 This is a one time calibration as long as you are using the same
sound card.
 Download CheckSR software and follow instructions.
http://www.pa-sitrep.com/checksr/CheckSR.exe
 We will demonstrate when we set-up FLDIGI.
Setting up the NBEMS Suit
 Configure FLDIGI First.
FLDIGI
FLMSG
FLWRAP
 Configure FLMSG.
 Configure FLWRAP
 DEMONSTRATE NBEMS SOFTWARE
CONFIGURATION AND USE.
 Demonstrate messages being sent via acoustic
coupling.

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