PSK31 & digital mode transmissions

BPSK31 has become the Number One HF digital mode for casual keyboard-to-keyboard operating. Although not an error free digital mode, it does offer excellent weak-signal performance. PSK31 has been embraced by the QRP (low power) community since a couple of watts and a simple wire antenna can be used to work stations throughout Europe and some DX.. BPSK31 uses 30hz wide signals and low power transmitters. A basic PC is needed (486/66 or better) running Windows 95/98 and a standard SoundBlaster16 sound card.

Some frequencies on each HF band are commonly used for BPSK31 operations:

7035.15 for region 1 and region 3, and 7080.15 for region 2 *
21080.150 (although most activity can be found 10 kHz lower)
* This is due to the fact that the 7 MHz band is much wider in region 2 (the Americas), and the IARU bandplan reflects this.


BPSK Bandwidth Of Properly Transmitted Signal

QPSK Bandwidth Of Properly Transmitted Signal

A kind of interfacing circuit that permit to use pc's soundcard for PSK31, note this circuit have a kind of groud separation between PC and transcieiver to eliminate possible loop current and other interference

An interesting PTT circuit from G3VFP to cover both the RTS and/or DTR source.
You can use a 2N2222 in place of the BC337 transistor in this circuit.

Soft and Hard for PSK31

(From: )

There is much software for getting in the air on PSK31. You can choose based on the Operating System of your computer and after that based on the hardware you have. You should read the notes for the compatibilities between DOS and Windows versions.

This is also the main distribution point for Peter G3PLX's  implementation reference software, known in it's Windows compatible version as P31SBW or PSKSBW. It is here but will also be able to get last english version requesting




You should always check for general Ham & linux applications at


Operating System Independent

PSK31 by Hardware, or should I say, Hardware independent? ;-)

Various pieces of software...

... and some pieces of Hardware 
(for interfacing to Sound Boards)


Some other Links (in Italian..)


Recommended frequencies for digital modes

Active digital mode frequency list compiled by Jason Buchanan - N1SU


There is a lot of discrepancy as to what frequencies are recommended vs. desirable for use on the digital modes. Other modes like MT63 are even more confusing because of their robust flexibility - interleave and width for example. One person's favorite may or may not be another's favored digital mode frequency. The most common digital mode frequency is 14.070 USB - I have success at starting a QSO with PSK31 and then QSY up the band and switch to another mode.

The list below should be considered a guide and not the required frequencies. You may have to tune up and down a few KC to find other active stations. The 20 meter frequencies are probably the most active but are also subbands for RTTY and packet use so be mindful of others!

Region 1 Europe digital mode frequencies are typically in the lower portion of the band which is an SWR bonus if your antenna is tuned for the CW portion of the band.

Soundcard digital modes are used using USB, never LSB. Clover, RTTY, PACKET, AMTOR and PACTOR typically use LSB, however.

Frequencies listed below are for dial QRG:


160 meters

1807 - PSK31, MT63 and MFSK
1838 - PSK31 and MFSK

80 meters

3580 - PSK31 and PSK63
3582 - MFSK16 and MT63 500Hz Short interleave
3585 - MT63 1000Hz Long

40 meters

7030 - PSK31 - Europe PSK frequency
7035 - PSK31, MT63, digital modes for all DX 7037 - MT63 - Europe MT63
7035 - PSK31

30 meters

10132 through 10139 - PSK31 and other modes
10137 - MT63

20 meters

14064.5 - Clover
14065 - Clover
14070 - Just about everything MixW offers can be found here
14109 - Mostly MT63, some MFSK and occasional Q15X25
14109.5 - Q15X25 - MixW centers at 1375Hz above VFO frequency. I use the settings that Ron KA2HZO have documented on his website.
14111 - same as 14109.5
14113 - same as 14109.5
14115 - same as 14109.5

17 meters

18100 - PSK, MT63 and other modes

15 meters

21109 - PSK, MT63 and other modes - MT63 on sked
21130 - PSK, MT63 and other modes - EU
21070 - PSK, MT63 and other modes

12 meters

24920 - PSK, MT63 and other modes
24930 - MT63 in Europe, although this is the upper edge of the CW/data subband in the US and is the 12m NCDXF beacon frequency

10 meters

28120 - PSK, MT63 and other modes
28130 - PSK, MT63 and other modes

Digital modes excel at LOW power. Using more than 20 watts causes interference to others on the band (AGC pumping) and does not help get you through poor band conditions. MFSK16 will work quite well at 5 watts.

Common practice today, unfortunately, has been to run digital modes at the highest possible output power. If QRO is necessary to accomplish a QSO, regulate the output power using the microphone gain while PC audio output is at maximum - do NOT connect your computer's amplified output to your radio, use only the line level outputs. Using the amplified outputs typically produce distortion and splatter the band. The cleanest signal transmitted typically can be obtained by using lower microphone gain and higher line level output volume. As with all digital modes, speech processing and ALC should never be used. PEP wattmeters should be used to determine the actual output power.

ZL1BPU has written an excellent book about digital modes. Look for his book titled Digital Modes for All Occasions The book contains information about mode duty cycles and bandwidth which is quite useful when determining our rig's capability to run the different modes.

The best way to guarantee successful contacts with digital modes other than PSK31 is to email the mailing lists and set a sked, or QSY up the band a few KC and switch to a different mode.

This list is very open to suggestions and corrections - please send any corrections/comments to me. If you know of other frequencies that are more popular than those listed above please let me know!

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