Presentation on binary phase shift keying

1. Write-Log, Binary Phase Shift
Keying (PSK31), Digital
Panoramic Tuning (DigiPan)
and Radio Set-Up.

2. Write-Log
Click her to open this box.
Set the frequency and mode
before operating.
Click FSK for PSK-31 Contacts.
Please try not to forget to avoid
unnecessary editing.

3. Write-Log
Super Check Partial
Click Window
Click Window then
then Super Check Partial
Band Summary.
Networking will
display all
Stations. Click Contest
then
Multipliers
Logged Stations
Enter Call, Operating Class and Section.
Tab over by using Space Bar
“Alt W” Clears this entire row. Left, Right Arrows and Backspace allows for editing.

4. What is PSK31?
• PSK31 was developed by Peter Martinez (G3PLX) and
introduced to the amateur community in December 1998.
• PSK31 was also known as Varicode Mode (Variable
Number of Bits)
• From the perspective of the transmitter, this amounts to
little more than somebody whistling into the microphone.
• PSK31 rapidly shifts the phase of the audio signal
between two states. These shifts serve the same function
as two FSK tones traditionally used by RTTY.
Instead of shifting frequency we’re shifting phase.
• PSK31's bandwidth of 31.25 Hz was chosen because a
normal typing speed of about 50 words per minute
requires a bit rate of about 32 bits per second (1Bit/Hz).
• PSK31’s 31.25 Hz can be derived from the 8 KHz sample
rate used by the DSP chips in computer sound cards

5. What is PSK31?
BIT Value Amount of Degrees of
Shift Shift
0 None 00
1 1/2 1800
Time Domain
Frequency Domain

6. PSK 31 vs. RTTY
• The chart at the right shows
the BIT Error Rate (BER) as a 1
function of Signal-to-Noise
ratio in a noiseless 0.1
environment. 0.01 RTTY
• Note: BER is the number of BIT’s 3
1 .10
received in error. For example, a
BER of 10-5 is 1 erroneous BIT 1 .10
4
received in error out of 100,000.
Bit Error Rate
5
1 .10
• For Signal-to-Noise (S/N) PSK-31
PSK-31
ratios greater than 10 dB, 1 .10
6
PSK-31 is virtually error free. 1 .10
7
• S/N=10Log(Power of the Signal ÷ 8
1 .10
Power of the Noise). In other
terms, if the noise level is 1uV 1 .10
9
QPSK-31
then you need 3.16uV for 10dB
S/N 1 .10
10
0 5 10 15 20
• At poor S/N ratios the BER of
PSK-31 is five times better Signal-to-Noise Ratio (dB)
than RTTY
• Note the curve that represents
QPSK-31.

7. PSK31 - Real World Performance
• The power in a PSK-31 signal is concentrated in a 31.25
Hz bandwidth versus 250 Hz (BW not frequency shift) for
RTTY and 3300 Hz for SSB.
• Assuming 100 watts of transmit power, the PSK-31
signal has 3.2 watts/Hz vs. 30mW/Hz for SSB.
• If a signal provides 20 dB S/N ratio at the receiver using
SSB, the same S/N ratio is achieved with 8W using
RTTY and only 1W using PSK-31!
• Lower Case characters are more efficient than upper
case due to Varicode (not to be confused with ASCII or
Binary code). PSK31 characters contain a variable
number of bits.
• Lower-case PSK31 characters have fewer bits than their
upper-case equivalents, so lower-case text transmits
faster and decodes better
• For example, the letter “a” has the Varicode 1011. The
capital letter “A” has a Varicode of 1111101.
– The letter “a” has four BIT’s

8. FYI: The better alternative
QPSK31
• QPSK31 has FEC convolutional code; lowers
the number of errors
• Forward Error Correction (FEC) is when
redundant data is sent 900 out of phase with the
primary data stream.
• A Viterbi Decoder decodes the bit stream and
estimates likelihood the data is correct or not. If
not it corrects the error.
• Under very poor propagation conditions (like
now); 1 out of 5 PSK-31 characters get thru
compared to 1 out of 2 QPSK-31 characters.

9. DigiPan – Signal Channel
This is the
Receive
Window
Right Click to put
cursor on the signal
you want to
receive.
This is the
Transmit Window

10. Preset FD
Macro's
DigiPan – Multichannel
3A NNJ
Click Call
Goes here
CQ
IMD

11. Radio Set Up
• PSK-31 is a 100% duty cycle mode. For all radio’s
reduce power by 50%
• Turn Audio Compression OFF
• With MIC Gain very low and power very low click T/R
button on DigiPan to Transmit
• Adjust MIC gain so ALC has little or no needle
movement
– This is to prevent Inter-Modulation Distortion from being transmitted.
Digital waveforms inherently produce IMD’s.
• Adjust power to ~50W (typical).
• Re-adjust MIC gain for little or no ALC needle movement
• Re-adjust power output.
• Click T/R again to go back to Receive
• You can operate any mode that you please; SSB, CW or
PSK-31. All three HF stations will have full three mode
capability.
• If you don’t know ASK!!! Don’t guess!!!