PSK31and

WSPR

May 2010KWARC

Nick Waterman VA3NNW&

Don Fisher VE3ESE

PSK31 Introduction Still the fastest growing digital mode

worldwide Needs:

Some software (almost always free)Any computer with a sound cardAny reasonably stable transceiverAn antenna… and really not a lot else!

PSK31 Introduction Very narrow bandwidth, much narrower

than RTTY, comparable with CW Gets through like CW (OR BETTER) at

comparable power and S/N ratio Manages about 50 wpm

PSK31 Introduction Good for ragchews and nets, good for

QRP and DX No error correction, so less good for

error-free file transfer, mailboxes, etc. PSK31 category in ARRL Field Day

(more points, more mults?)

PSK31 Error Rate

0 5 10 15 201 10

10

1 109

1 108

1 107

1 106

1 105

1 104

1 103

0.01

0.1

1

Signal to Noise Ratio (dB)

Err

or R

ate

PSK-31

RTTY

100W SSB ≈ 8W RTTY ≈ 1W PSK31 –You WILL NOT NEED a lot of power !

(Chart borrowed from YCARS, with thanks)

PSK31 Stands for... Phase Shift Keying, 31 Baud Specifically Binary Phase Shift Keying

(So sometimes called BPSK31) 31.25 baud (so BPSK31.25 ?) There's also a QPSK31 (Quad Phase

shift keying), uses 4 phases instead of 2, some error-correcting, but less common. There's also PSK63, PSK500, and some other variants, won't go into too much detail on these.

PSK31 History Developed by Peter Martinez (G3PLX) and

introduced to the wider amateur radio community in December 1998.

Martinez initially called his creation "varicode", because it uses variable length encodings (Huffman codes) to represent characters (more on that later)

The slightly obscure 31.25bps bit rate was chosen as being a nice binary multiple of the sound card clock rate (8kHz/256)

PSK31 Waveform Unmodulated carrier:

CW:

BPSK (bad)

BPSK (good)

In phase 180º out

Phase changes

Phase changes

PSK31 Encoding A “0” is sent as a 180º phase shift

A “1” is sent as no phase shift

0 1 1 0 0 0 00 1 1 0 0 0

The “alphabet” is then designed to make sure that commonly-sent characters are made up of a small sequence of 1s and 0s, rare characters are longer (a little like CW)

There are never too many long strings of 1s (difficult to tell how many 1s belong on a long carrier with no phase changes to sync off).

The gap between chars is “00”. Long string of 0s when idling

This alphabet is called Varicode

PSK31 Varicode Alphabeta 1011b 1011111c 101111d 101101e 11f 111101g 1011011h 101011i 1101j 111101011k 10111111l 11011m 111011n 1111o 111p 111111q 110111111r 10101s 10111t 101u 110111v 1111011w 1101011x 11011111y 1011101z 111010101

A 1111101B 11101011C 10101101D 10110101E 1110111F 11011011G 11111101H 101010101I 1111111J 111111101K 101111101L 11010111M 10111011N 11011101O 10101011P 11010101Q 111011101R 10101111S 1101111T 1101101U 101010111V 110110101W 101011101X 101011101Y 101110101Z 101111011

SP 1

0 101101111 101111012 111011013 111111114 1011101115 1010110116 1011010117 1101011018 1101010119 110110111

! 111111111" 101011111# 111110101$ 111011011% 1011010101& 1010111011' 101111111( 11111011) 11110111* 101101111+ 111011111, 1110101- 110101. 1010111/ 110101111: 11110101; 110111101< 111101101= 1010101> 111010111? 1010101111@ 1010111101[ 1010101101\ 111110111] 111101111^ 111111011_ 1010111111. 101101101/ 1011011111{ 1010110111| 110111011} 1010110101~ 1011010111

NUL 1010101011SOH 1011011011STX 1011101101ETX 1101110111EOT 1011101011ENQ 1101011111ACK 1011101111BEL 1011111101BS 1011111111HT 11101111LF 11101VT 1101101111FF 1011011101CR 11111SO 1101110101SI 1110101011DLE 1011110111DC1 1011110101DC2 1110101101DC3 1110101111DC4 1101011011NAK 1101101011SYN 1101101101ETB 1101010111CAN 1101111011EM 1101111101SUB 1110110111ESC 1101010101FS 1101011101GS 1110111011RS 1011111011US 1101111111DEL 1110110101

Worth noting:Really Short

Also: Typing ALL IN CAPS will actually slow you down! ☺

PSK31 - Operating

Line outSound card

Line in

Mic Audio out

PSK31 - Operating

Line outSound card

Line in

Audio out100k 1k

Mic

Bit of attenuation often helps.Some people do clever stuff with isolation transformers, capacitative DC blocking,

opto-isolators, etc.

PSK31 - Operating

Line outSound card

Line in

Audio out100k 1k

Mic

PTT via VOXBUT BEWARE any other sound

coming out of your computer (web page audio, MP3s, and even windows startup jingle)

may be transmitted

PSK31 - Operating

Line outSound card

Line in

Audio out100k 1k

Mic

PTT via regular CAT cable(same one you use for rig

control, programming memories etc)

PSK31 - Operating

Line outSound card

Line in

Audio out100k 1k

Mic

22k

2N2222

1N4148PTT

SerialRTS

PTT via serial port(RTS, DSR, or similar

signal line)

PSK31 - Operating

Mic

Audio out

Sound Card Interface

West Mountain Radio RIGblaster (about 5 types)MFJ make a fewMicroHAMRigExpertSignaLinkMany more, inc many homebrew designs starting at about $10

PSK31 - Operating

If you're feeling REALLY cheap, some people get away with simply putting their rig mic near their computer speaker and vice-versa! This provides good electrical isolation, but it's tricky to get the audio levels right, ambient noise can ruin your transmitting or receiving, and besides, PSK31 doesn't sound all that nice anyway!

PSK31 - Software

SOFT-WARE!

MixW - www.mixw.net MultiPSK -

http://f6cte.free.fr/index_anglais.htm DigiPan -

www.pavane.net/digipan/digipan.htm Fldigi - www.w1hkj.com/Fldigi.html Hamscope - www.qsl.net/hamscope WinPSK, Zakanaka (with Logger32) Plenty of others. Almost always FREE Usually includes multiple other digital

modes (RTTY, Olivia, Hell, sometimes packet, SSTV)

Often includes logging software, some level of CAT, rotor control

PSK31 - Software

SOFT-WARE!

This is what we'll be using for the demo

MixW - www.mixw.net MultiPSK -

http://f6cte.free.fr/index_anglais.htm DigiPan -

www.pavane.net/digipan/digipan.htm Fldigi - www.w1hkj.com/Fldigi.html Hamscope - www.qsl.net/hamscope WinPSK, Zakanaka (with Logger32) Plenty of others. Almost always FREE Usually includes multiple other digital

modes (RTTY, Olivia, Hell, sometimes packet, SSTV)

Often includes logging software, some level of CAT, rotor control

PSK31 Audio Settings Windows audio mixer or equivalent Adjust “Line In” volume until the waterfall looks

nice or until the stronger signals are using about 50% of the available range.

Adjust “Line Out”, “Headphone”, or “Wave” (and make sure you're using the right one) until your rig ALC is barely deflecting and flat, and again about 50% power output is probably ideal

Make sure you're not overdriving or clipping in either direction – will cause bad IMD (inter modulation distortion). Vol DOWN if you are.

Compression OFF on your rig

PSK31 Frequencies 1.83815 MHz 3.58015 MHz 7.035 MHz 7.07015MHz 10.13715 MHz 14.07015 MHz 18.10015 MHz 21.070 MHz 21.08015MHz 24.920 MHz 28.07015MHz 28.12015 MHz 50.290 MHz

PSK31 - Demo

(White with two sugars please!) ;-)

WSPR Pronounced “Whisper” Weak Signal Propagation Reporter, by K1JT Definitely NOT for ragchews Not even really QSOs This mode effectively turns your PC+Rig into a

beacon, but also monitors for, and reports, other people's WSPR beacons.

Good use of your Rig when you're not using it! You can be heard WORLDWIDE on <1W,

We've seen spots of 13,000km on 0.1W or less

WSPR - timing

Time is divided into 2-minute slots (it helps to have your PC sync'ed over the net using NTP, any of the free atomic clock tools or just Windows time sync)

You will occasionally transmit for a 2 min time-slot (actually 110.6s)

You will usually receive in all other 2-minute time-slots, and automatically report any “spots” to the wsprnet.org website, assuming you have “always on” internet.

WSPR - Encoding VERY slow data rate (1.4648 baud) –

you take 2 minutes to transmit just your callsign, your 4-digit Maidenhead locator, and your power level.

Tonnes of error-correction to ensure you can be heard at -28dB

If you want to use a callsign with prefixes or suffixes, or a 6-digit locator, there are special ways to send it, and you end up taking 4mins instead of 2

WSPR - Encoding

4-FSK, tone separation 1.4648 Hz Occupied bandwidth: about 6 Hz Not going to go into all the details of the

error-correcting codes, there's some complex coding theory there...

… but for operating it really doesn't matter, the software is trivial to run, you just set it up and leave it running.

WSPR - Operating

Line outSound card

Line in

Audio out100k 1k

Mic

EXACTLY THE SAME AS PSK-31!*

*(Just different software)

WSPR

Software:http://www.physics.princeton.edu/pulsar/K1JT/

Reports:http://wsprnet.org/http://wsprnet.org/olddb?findcall=VE3IC&findreporter=VE3IC

Who's on the air?http://wsprnet.org/drupal/wsprnet/activity

WSPR - Demo

QUESTIONS?

?

THANKS!

This presentation is at:http://noseynick.net/va3nnw/PSK-talk/