Tip & How-To about Audio Players & Recorders

10 Tips for the PSK31 Digital Mode

PSK31 is arguably the most popular amateur radio
digital mode. It utilized phase-shift-keying to
provide robust, narrow signal width communications,
and requires very little power to QSO the world!

- Use the center of your waterfall. Testing will
show that your transmit (TX) and receive (RX)
will be strongest there. Don’t blindly use 1000Hz
tone or strictly follow the VFO ‘set it and forget it'
concept. You can easily lose 20% or more of
your power on each edge of your pass band.
Pass band centering of the signal will give the
best results of both RX and TX.

-There's no need to have the waterfall streaking
bright red. Set your rig's volume to a low level
(less than 25% of max) and adjust your waterfall
and soundcard levels for a good contrast. Do not
overdrive your soundcard! Get the background
noise and the transmit trace well defined and
separate. Keep in mind, how your waterfall looks
does not impact decoding, but it is harder to work
it if you can’t see it.

- Use UPPER CASE characters sparingly. Lower
case text in PSK31 varicode transmits fewer bits
of data, thus you'll increase transmit speed and
improve the likelihood of proper decoding on the
other end. For example, the difference of a
lowercase e and an uppercase E is five times
more bits! (e=11 vs. E=1101101101)

- Enable your RF Attenuation and increase the
volume. This helps keep a strong signal from
wiping out the weaker ones. Attenuation will
probably be around 20 dB, but by dropping the
noise level, the signal readability improves. AGC
(auto gain control) does nothing for a weak
signal; it only levels the louder ones.

- Use your digital modes software, or a program
like Spectrogram, to see what you noise level is
with the radio off. This will give you an idea of
how 'clean' your soundcard is. Typically,
onboard (built-in) sound hardware (as found in
most 'mainstream' computers like Dell or HP)
does not have a signal-to-noise ratio as good as
an inexpensive (less than $50) separate
soundcard. When purchasing a soundcard, look
for something with over 100 signal-to-noise ratio
in the specifications.

- Consider dual monitors (most modern video
cards have two jacks). This allows you to have
the waterfall or spectrum display on one screen,
and your logger, text window, etc. on the other. It
makes a huge difference in speed and ease-ofuse
when you don't have to swap between
screens or use smaller windows for your QSO.

- Keep your ALC reading during transmit to as
close to zero as possible. This will keep your
signal clean and your IMD at a good level (-20s
or better is ideal). Your power output will drop,
but there's no need to 'smoke' the transmit level.
PSK31 is about an 80% duty cycle. Even with a
full duty cycle rig, it still needs to dissipate heat!
Besides, 20 watts more makes little difference.
Output of around 50W is enough to work the
world, and your fellow CQs will appreciate the
courtesy. Also be sure your voice processor is
NOT enabling when using digital modes.

- Ask for an RSQ (readability, strength, quality)
report! When in a QSO, send just a tone and ask
for your IMD and a report on how your trace
looks. This will give you a better idea of
adjustments needed.

- There are hundreds of digital modes. To get
started or to learn more about the most common
ones, acquire ARRL’s ‘HF digital handbook’ by
Steve Ford, WB8IMY. For the technical types, be
sure to snag Roland Prosch’s (DF3LZ) ‘Technical
Handbook for Radio Monitoring’.

‘BONUS’ TIP:
- Try 30 meters PSK31! It’s a robust band, offering
the best of 20M and 40M. It’s a small segment of
a no contesting band. Used only for digital
modes and CW. Be sure to operate within your
privileges. PSK31 can typically be found around
10.140.

DEFINITIONS of TERMS USED:

AGC (Auto Gain Control): The ability to reduce
signal strength on-the-fly (fast or slow), giving you a
more level audio reception on stronger stations.

ALC (Auto Level Control): A voltage adjustment or
reading, indicating your TX signal levels . ALC is
designed to control voice and carrier signal levels,
not digital modes. Typically, if the ALC meter moves,
then the microphone gain is too high.

Signal-to-noise (S/N) ratio: A comparison of the
signal levels to the relative noise level. Ideally, a
perfect signal would have no noise, but realistically,
you’ll want a S/N ratio well within the tolerances of
the mode you’re using. PSK31 tolerates about a
10dB S/N ratio.

dB: Sound level, or ‘decibels’ are used to measure
the relative strength of a signal.

Digital Mode: A converted signal transmitted from
your radio to be ‘de-converted’ by the receiving
station. Much like a computer modem, a digital feed
is converted to analog, sent across a transmission
medium, then reconverted back to a readable signal
at the receiving station.

Duty cycle: The total time of actual transmission
levels. When your radio is transmitting, there’s an
on/off process that takes place. Transmitting at a
100% duty-cycle indicates that your are using 100%
of your radio’s power, 100% of the time. Better
radios will allow this, while others will eventually fail
under the pressure of such a load.

IMD (Intermodulation Distortion): The ratio, in dB,
used to determine the quality of your transmission.
Unwanted ‘products’ or signals reduces IMD levels.
More power does not mean better copy!

Overdrive: Turning the volume of your radio up so
high that you risk damage to the soundcard, or cause
signal ‘splatter’. Similar to maintaining your ALC
levels.

Pass band: The range that your transceiver can
receive when on a single frequency. Typically
around 3000Hz wide.

PSK (Phase Shift Keying): A form of modulation
that shifts the transmit signal in order to carry more
information. PSK31: is a digital mode created in the
1990’s by Peter Martinez (G3PLX) that is about 31Hz
wide on your waterfall.

RF (Radio Frequency) Attenuation: A suppression
of signals received. You’ll often see a noise level
reduction, with a minor sacrifice to the desired signal
reception. Check your radio’s manual on how to
adjust it.

RSQ (Readability, Strength, Quality): Much like the
familiar ’RST’ reports, using a 599-type reporting
scheme. Instead of ‘Tone’ (Morse Code), use
’Quality’. 95%+ readable, with a very strong waterfall
trace, and a clean (no splatter) signal would warrant
a 599 report.

Soundcard: A piece of hardware in your computer
that produces sound, and often allows input, as with
a microphone.

VFO (Variable Frequency Oscillator): It’s that knob
you use to change frequencies on your radio.

Varicode: A streamlined coding system that allows
nearly whatever your computer keyboard can type to
be transmitted in shorter lengths.

Waterfall: A visual display of radio signals (and other
sounds) found on the tuned frequency.

RELATED WEB LINKS:

ARRL’s ’HF Digital Handbook’,
by Steve Ford, WB8IMY
http://www.arrl.org/catalog/?item=1034

‘Technical Handbook for Radio Monitoring I’,
Roland Prosch’s (DF3LZ)
http://www.hoka.com/th/th_book.htm

Digital Master 780, by Simon Brown, HB9DRV
http://hrd.ham-radio.ch/DM780/DM780.htm

Spectrogram and other software:
http://www.visualizationsoftware.com/

Posted by on

Audio Players & Recorders Logo

Related Topics:

Related Questions:

1 Answer

Why can I not get through to any Government Dept. The phone does not even ring. ( SARS and CIPC )


Sorry... Desiree van Eeden,

If you are someplace that is having a disaster
you will probably be out of phone service for quite a while.
(a bit cumbersome.. this mediun and your local emergency services CAN communicated here as well
(if they've any brains at all)).

I am an old twice retired phone man.

I'm also an AMATEUR RADIO OPERATOR... I can assure you
the voice communications of the cellular network would be the FIRST THING TO FAIL in any kind of congestion...

If you want to continue to try cellular... attempt to TEXT...

FIND a land line... (of fashion twisted copper pair)...
Digital Packet phones are also likely to fail...

Search out a nearby AMATEUR RADIO ...OPERATOR...

Check out local boat yards for MARINE - MOBIL radio service...

Or you can fashion a regular car ignition coil and car antenna
into a large spectrum noise generator... keeping in mind this
could interrupt other communications... SPARINGLY TAP OUT MORSE CODE:
VERY Quick connects of the GROUND wire = a "dot" (.) and
less quick connects = a "dash" (-)
where "S O S" = ... --- ...

For USA emergencies... as a last resort I would try "citizens band" (typically channel 9)


SOME HIGHLY dedicated HAMS (amateur radio operators) maintain communication contact and relays to get through
to the outside world.

Hope this helps

Nov 17, 2016 | Cell Phones

1 Answer

does digital mean the tramsmitions are printed out on the screen?


no
It means the radio transmissions are converted from analogue sound waves into a digital format. Then the radio uses a phase shift technique to encode digital information on what is in reality an analogue radio signal.
The receiver then converts the digital signal back to analogue for the sound waves out the speaker.
The advantage is that amplitude variations do not affect the quality of the radio and error correction techniques may also be employed to fix errors in the digital information.
https://en.wikipedia.org/wiki/Phase-shift_keying

Feb 17, 2016 | Radio Communications

2 Answers

yaesu ftm-10e squelch problem


The FTM-10E is the european version of the dual band amateur radio capable of transmitting in the amateur VHF & UHF (144Mhz & 440Mhz ) bands, that is equal to the FTM-10R sold in the US.

Many repeaters require a predetermined sub-audible tone or signal to be sent when transmitting. If several repeaters in the area operate on the same frequency, they would all transmit at the same time unless they all have different sub-audible tones. These tones allow the user to select which repeater on the same frequency will be used. The tones are either CTCSS or DCS type. CTCSS is "continuous tone coded squelch system" and DCS is "digital coded squelch". CTCSS is expressed as a frequency in Hertz and DCS is a code expressed as a number. CTCSS is more popular, since it has been around longer. When programming or tuning the radio, you will need to provide the repeater's output frequency (and the input frequency if the shift direction and amount isn't programmed - often a 600 hertz shift either up or down depending on isn't already programmed is a default value depending on the repeater output frequency) and whether or not the repeater requires a tone. If it does require a tone (most do), you will need to know the type (CTCSS or DCS) and the value (frequency for CTCSS or code number for DCS) in order for your transmitter to open the repeater and cause it to repeat your transmission AND open the squelch on the radio's receiver so that you can hear replies to your call and other conversations. Repeater directories (both printed and online) will provide all the information needed to access a public repeater, including geographical location, input & output frequencies, squelch type and values to name a few.

If you do not have the correct CTCSS or DCS set, you will see the signal meter on the radio indicate traffic - but you will not hear anything because the radio is squelched. Check the manual page 40 for information on how to program the squelch, and page 42 describes the "shift" I mentioned above. Page 64 & 65 details the theory of squelch via CTCSS and DCS and will help you understand it better.

Basically, you have a "standard" squelch - the knob on the radio and a second squelch that is either CTCSS or DCS. Both types must be set to hear anything. Not having the CTCSS or DCS set will prevent your signal from being repeated by the repeater.

If you have more question, please add them in a comment. I hope this helps & good luck!

Jun 17, 2012 | Yaesu FTM-10R VHF/UHF Mobile Dual-Band...

2 Answers

Is it possible to convert the cobra 29 wx nw st sound tracker cb to 10 meter amateur band?


No it cannot. If you want that buy a Ranger or a Galaxy.

The 29 can be altered to increase modulation and turned down in power to match it to amp for increased output of power.

Set to dead key a watt or so with a 100 watt amp it would dead key low and swing to 80 to 100 watts pep.(peak envelope power)

Mar 16, 2012 | Cobra Radio Communications

1 Answer

communication


To modulate the signal just means to systematically vary one of the three parameters of the signal: amplitude, frequency or phase. Therefore, the type of modulation may be categorized as either AM: amplitude modulation FM: frequency modulation or PM: phase modulation

Dec 17, 2008 | Audio Players & Recorders

Not finding what you are looking for?

1,566 people viewed this tip

Ask a Question

Usually answered in minutes!

Top Audio Players & Recorders Experts

kakima

Level 3 Expert

102366 Answers

 Grubhead
Grubhead

Level 3 Expert

5158 Answers

The Knight
The Knight

Level 3 Expert

74383 Answers

Are you an Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Loading...