Skyview Radio Society Digital Elmer Night

Digital Sound Card Modes and Operation

UR report… 599 599 fb copy on all, 100% print

Advantages of Digital Modes:

• Great for reliable rag-chew

• Many modes - choose your mode depending on conditions

• Emergency Communications

• It’s FUN

• Bottom of the solar cycle - works well, even under very poor conditions where phone QSO’s would be impossible!

PSK31 Olivia 500Hz/16 tones

Olivia 500Hz/16 tones

MFSK16

• Low Power - never need to run over 50 watts, 5 -30 watts is almost always sufficient (try 500mw… you may be surprised!)• Spectrum efficiency

Hardware•Windows Computer

•HF Radio/Antenna

•Sound Card Interface?

•Or, maybe just a $8 computer microphone?

To start playing around... all you need is an inexpensive computer microphne! Just plug a mic into your sound card mic input and place the mic element somewhere near your radio speaker. Listen and

watch your display and practice differentiating the various modes.

Sound Card Interfaces and USB Sound Cards

•Sound Card Interface connects from your computer sound card to your radio, provides RF isolation and automates the PTT when you transmit (PTT via either VOX or Serial)

•USB Sound Card provides the same connection and function, but it has it’s own built in sound card (only 2 cables)

The Signalink USB Sound Card has the advantage of it’s own independent sound card, and volume controls on the device. Only requires two cables (provided), one for the connection to your radio and the other (USB) to connect to your computer.

$99 Excellent value!

Is this is a Waterfall?

Here is a REAL waterfall...

Live waterfall demonstration…

Basic Sound Card Digital Modes•PSK31 - easiest and most common mode

•PSK63 - twice as wide… twice as fast

Accuracy, speed and audio bandwidth all come into play and various modes all have their advantages and disadvantages!

•MFSK(16) - Better for weak signals and motors right through static crashes!

Why not always use the fastest , most narrow mode?

Why use the much wider (250Hz) MFSK16 mode if it is the same speed as the very narrow (31 Hz) PSK31 mode?

•MFSK(16) - 8 times wider than PSK31, same speed

PSK31

PSK63

MFSK16

PSK31

PSK31

•USB or LSB - polarity doesn’t matter, but your radio should always be set to USB (standard for all digital modes)

•Sound card calibration is not critical (more on this later)

•Almost always... someone, somewhere running PSK31

20m USB - 14.070 MHz40m USB - 7.070 MHz80m USB - 3.580 MHz

Where to listen for PSK31 and PSK63:

And, don’t forget about 30m - 10.140 MHz

PSK31 IMDTurn that thing down!

Inter Modulation Distortion, or IMD is caused by overdriving your sound card audio into your radio and it makes a mess on the waterfalls of receiving stations!

•Set your radio to full power•Adjust your sound card master volume and wav volume down (double-click the speaker icon)•Set your radio meter to ALC (Auto Level Control)•Transmit, then adjust your master and wav volume to where the ALC meter just begins to register

Check out www.youtube.com for great instructional videos!Keyword search: PSK31 Transmitter Level Adjustment

PSK31 IMDTurn that thing down!

Here’s a fellow ham in a QSO elmering another ham on the subject of IMD.

Ask other hams how your IMD looks. And don’t be afraid to elmer other hams on their IMD. You’re not doing them any favor by ignoring the problem!

IMD measurements can only be made when receiving a signal with no text. A -20 dB or lower IMD is what we should all be shooting for.

Ask the other operator to transmit a bit without typing so you can get an accurate IMD reading. Do the same if you ask someone for your IMD reading.

PSK31 IMDTurn that thing down!

PSK31/63 Software

•Digipan - free, easy to use

PSK31/63 Software

•Digipan - can also display multiple QSO’s

PSK31Good Conditions to Europe!

(April 21, 2008, 2150 UTC)

MFSK(16)

MFSK(16)Multiple Frequency Shift Key - 16 tones

The fade in the MFSK signal as seen on the waterfall below had no effect on the decoding of the text (or print). PSK31 or 63 would have suffered serious data loss under the same conditions. Forward error correction (FEC) and interleaving provides very good copy under week conditions.

The trade off (you never get something for nothing) is speed and bandwidth as compared to PSK31 or 63.

Note: this MFSK signal was inverted, or reversed… more on this shortly

MFSK(16)Software for MFSK

Free:

•NBEMS (VBDIGI)

•Ham Radio Deluxe (HRD DM780)

•MultiPSK (for advanced digital operators)

Purchase:

•MixW - $50 (and runs almost all modes)

My opinion… NBEMS and MixW are the easiest to use, best designed, multi-mode digital software packages.

MFSK(16)When to use:

•Whenever you want to!

•When conditions are too weak to carry on a PSK31 QSO (ask to change modes!)

•For longer rag-chews, in case conditions deteriorate

•During conditions with static crashes and light fading

Where to use:

•Most commonly found just above the PSK31 frequencies

•80m 3.581 - 3.585 and 20m 14.073 - 14.075 are where you will see the most activity

Tips:

•Tuning is more critical than PSK31. When you adjust the position on the waterfall, do so slightly. WAIT at least 2 seconds (FEC – Forward Error Correction delay) to see if the adjustment results in accurate print before readjusting

•Make sure your radio is set to USB and the software “inverse” or “reverse” is not activated. If you can’t decode, try the “inverse” or “reverse” setting. If that doesn’t work, the signal may be olivia 250hz

•Make sure your sound card is properly calibrated

MFSK(16) Screen ShotMarker Tone

When properly polarized (USB), the leading (and usually the trailing) edges of MFSK16 taper off to the left. If you see this pattern, you’re almost certainly looking at an MFSK16 Signal.

MFSK(16) Screen ShotTuning Marker

Line up the tuning marker with the MFSK16 marker tone on the left.

MFSK(16) Screen ShotPicture Mode

MFSK(16) also has a small picture mode that is extremely easy to use. The software automatically switches into picture mode on RX.

Sound Card CalibrationCheckSR

http://www.mixw.net/files/CheckSR.exe

Sound card accuracy is much more critical for the MFSK modes (MFSK16, Olivia) and other modes such as MT63. The difference between your sound card transmit and receive accuracy is measured in parts per million (PPM) based on a given sample rate. If there is a discrepancy between your tx and rx sample rate, the result is the person on the other end of the QSO has to retune to your signal after every exchange.

CheckSR is a free program that makes the calculation for your given sound card offset error. Run the CheckSR application with either 8000 or 11025 set for the sampling rate depending on what program you are running. Let the program run for about 5 minutes, then click stop and record the numbers.

Almost all of the software has a configuration setting for entering in the numbers from CheckSR. Many other programs such as MultiPSK have built in applications that will make the adjustments automatically.

PSK Signals

Sound Card error shift as a result of improper sound card calibration

Most PSK31/63 software will automatically track slight shifts with the AFC (Automatic Frequency Control) setting.

What are Macro’s?

Macro’s allow you to automate some of the QSO functions and commonly sent text. Macro’s can be easily customized.

A right-click on the macro buttons on most programs bring up an editing function that allows you to change the macro text or functions...

Customize your Macro’sAfter you right-click, an edit box comes up...

… program controls (TX and RX) as well as your call sign or the other operator’s call sign can all be configured so that one click on a macro button, for example, will key up your radio, insert the other stations’ call followed by your call and then put the radio and the software back into receive mode.

TIP: Add 3 periods followed by a hard return to your response macros (after the TX command). This helps distinguish your return transmission from random characters that appear on the other stations’ screen (diddle).

Macro Tip

Some Waterfall Screen Shots…

PSK31… what does this waterfall display tell you?

Overdriving audio… very bad IMD!

Very slow typist! (see all the empty space between the marker tones)

By the way, don’t use all CAPS… caps slow down the transfer rate when using PSK31 and several

other modes!

•By the way, don’t use all CAPS…

Oooof!

Advanced Modes TeaserOlivia – 250, 500 or 1000 Hz

8, 16 or 32 tones

Common Olivia operations are transmitted in 250, 500 and 1000Hz bandwidths. The screen shot above is Olivia 1000Hz/32 tones near the 20m frequency of 14.106 MHz. Tuning and sound card calibration are critical on this mode, but as you can see, Olivia is capable of maintaining near 100% copy under extremely adverse conditions.

All Olivia signals can be identified by two sets of alternating marker tones at the beginning of each transmission, unlike MFSK which transmits only the lower marker tone. The trick to decoding Olivia is determining the proper combination of bandwidth and tone settings.

Advanced Modes TeaserOlivia – Tips

• Always USB, inverted or reverse NOT selected in software• Select appropriate bandwidth setting first• Look at waterfall to estimate the number of tones• Listen… lower number of tones sounds garbled, higher number sounds like a flute rapidly playing random notes• Wait 2 seconds when adjusting RX tuning• Listen for a while before you CQ, especially on the 1000 Hz band plan• Higher number of tones = slower rate and greater reliability but tuning accuracy becomes much more critical

500 Hz wide

16 Tones

Advanced Modes TeaserOlivia – Screen Shots

500 Hz wide

Here you can see the start and end marker tones on Olivia.

Advanced Modes TeaserOlivia – Screen Shots

500 Hz wide

Here’s a DEEP fade with no loss on text!

Advanced Modes TeaserOlivia – Screen Shots

500 Hz wide

Here’s a perfect Olivia signal!

Thank you for viewing, and I hope

to see you on the waterfall!

This presentation may be distributed or used freely, without modification.

Feel free to contact the author of this presentation, David J. Kleber (KB3FXI). with any questions, comments or corrections.

Contact information is current on QRZ.com