2. 1 Digital Modes Doug Gallup AD7BN Presented to UARC April 4, 2008

3. 2 Purpose Talk about the different digital modes out there, and how to use them properly Show how to get on the air

4. 3 Digital Modes at AD7BN Started off on HF with PSK31 (3/2004)‏ First DX: DU (Philippines) on PSK31 Within a couple of weeks of casual operating 5W FK T33 4J0 GM Lots of W/VE stations

5. 4 Advantages of Digital Modes Very effective with low power Good for the smaller station Efficient use of bandwidth Good for working DX You probably have most everything to use it There's lots of easy to use software out there You don't need to know code (CW)‏

6. 5 RTTY Radioteletype Use has gone down with PSK31 Mode of choice for DXing and contesting 100% duty cycle Baudot code 45.45 baud, about 60 WPM Example: 11011 = FIGS control character

7. 6 RTTY FSK: Frequency Shift Keying To decode, you detect the pulse state of the signal Mark is the on pulse Space is the off pulse Shift is the difference between the two frequencies Mark tone is 2125 Hz below carrier frequency Space tone is 2295 Hz below Standard ham shift is 170 Hz

8. 7 FSK or AFSK? When properly set, they both transmit equally AFSK is possible on any SSB transmitter through your computer sound card With AFSK, you need to make sure you're not overdriving your equipment Special FSK or RTTY modes on your radio typically allow you to use narrow CW filters With AFSK, you may be stuck with a wide SSB filter (down to 1.8 kHz)‏

9. 8 PSK31 Often multiple stations are on at any given time Phase modulated audio “carrier” at 31.25 baud Phase reversal of 180 degrees Very narrow bandwidth 90% duty cycle, 60% when idling Protect your finals! Computer sound card only Uses Varicode (not ASCII)‏

10. 9 MFSK16 Frequency Shift Keying (FSK) on multiple frequencies (16)‏ Very good for DX, but tuning needs to be more precise About 250 Hz bandwidth, 31.25 WPM Less common than PSK31

11. 10 Other Sound Card Digital Modes Olivia, Throb, DominoEx, PSK63, etc.... Some work extremely well when the bands are fading or almost gone, when other modes won't work However, they are not as commonly seen as PSK31 or RTTY Some are experimental Use them in the same way you use PSK31

12. 11 “Fuzzy Modes” Work exactly the same as the other sound card modes, except the computer doesn't do the decoding, you do Transmit the same way as other modes Hellschreiber, PSK-Hell, etc.

13. 12 Clean Digital Signals Run everything linearly Do not use compression or your speech processor Do not have any ALC showing Clean signals improve copy, while overdriving does not

14. 13 Improving IMD IMD = Inter modulation distortion Don't want to overdrive or clip your signal Most PSK 31 programs can measure the other person's IMD when they idle Ask the other person to measure your IMD Start transmitting, but don't type anything Let it idle for a few seconds so they can get a reading

15. 14 Properly Adjusting Your Signal Adjust your audio drive level Use your sound card output volume control Mic gain also works, but it's usually fine if it's set for normal SSB operation Changing the power on your radio does not properly adjust the audio drive, it only changes the power of a bad signal Make sure the power output is reasonable Clean signals get through, even with low power

16. 15 PSK31 Splatter

17. 16 Volume Output Control

18. 17 Equipment: Computer Even older computers work fine with digital modes You'll need a free serial port (COM) for PTT VOX needs higher audio signals, which can result in unclean signals “Sound Card” digital modes need a sound card See May 2007 QST Product Reviews

19. 18 Equipment: Software RTTY: MMTTY is the best option, and it's free PSK31: Many choices, some of them free Digipan, MixW, Hamscope, Ham Radio Deluxe, MultiPSK, etc. Other digital modes: Included in some PSK31 programs, or separate Ex: IZ8BLY's Hellschreiber program

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23. 22 Equipment: Hardware For RTTY, you may already have an old TNC There are many digital mode boxes out there to interface your computer and radio RigBlaster, MFJ, SingaLink, homebrew, etc. Some contain their own sound cards (helpful if your computer doesn't have one)‏ Cables to interface between your computer, digital mode box, and radio Some newer radios have special line in and line out jacks for digital modes

24. 23 Minimum Equipment Setup Computer Radio PTT Serial port, USB Audio In Headphone, speaker Audio Out Line in, Mic in Headphone, Line out Mic, accessory port R R

25. 24 Equipment: Commercial Hardware

26. 25 Hints: Macros Set up your macros in advance This lets you easily press buttons to automatically type common parts of a QSO It's like a memory keyer for CW or SSB, but more flexible and interactive Really helps if you can't type very fast Some modes are faster than most people can type Helps with common ragchewing info or other parts of a normal exchange

27. 26 Hints: Pileups In a DX pileup, be sure to work split When multiple people are calling on the exact same frequency, the computer will only decode the biggest, loudest signal, so you need to spread out Hopefully, nobody is transmitting on the DX's frequency, frequency when they are giving your exchange

28. 27 Hints: Power Clean, low power digital signals do get through 519 PSK31 QSO with VK Just because you're using PSK31 doesn't mean you have to be QRP (> 5 Watts is not a sin)‏ You may annoy other using wide open SSB filters when you overload their receiver, though Just make sure your signal is clean

29. 28 Hints: Filtering RX If your radio has a special RTTY or FSK mode, use it instead of AFSK This allows you to use your narrow CW filters Otherwise, your RX will get overloaded by other strong, nearby signals Some newer radios will allow you to use narrow CW filters in SSB, check your manual

30. 29 Hints: Tuning Some modes are more forgiving than others On some modes you have to be exactly on frequency for it to decode, otherwise it's garbage If a program has “AFC” it will automatically tune a signal Sometimes you will manually have to override this by clicking on the waterfall It's like an automatic RIT, but it can also move your TX frequency as well Be careful when using this when you're running (calling CQ)... don't drift from your frequency

31. 30 Hints: Tuning 2 If you're using FSK, you usually don't want to use AFC (use RIT instead)‏ You'll drift away from your TX frequency If you're using AFSK, you can click anywhere on the waterfall to tune a signal However, stay within the transmit passband of your radio You aren't going to have much power output if you're generating audio tones around 100 Hz or 2700 Hz Stay somewhere in the middle, from 1000 Hz to 2000 Hz

32. 31 Demo