American QRP Club NUE-PSK User manual

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 1 Copyright 2008, American QRP Club
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The NUE-PSK Digital Modem is a standalone, battery-operated digital modem using
Microchip dsPIC technology. Weighing about 12 ounces and requiring only 60ma at 12V
DC, the modem is easily taken to the field. For easy visibility in high or low ambient
light, the NUE-PSK modem’s backlit graphic LCD displays transmit and receive text
data, as well as band spectrum and tuning indicator. When coupled with a standard PS2
or USB keyboard and an SSB-capable transceiver, you can have an effective portable
PSK31 station.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 2 Copyright 2008, American QRP Club
CONTENTS
1) Introduction ............................................................................................................ 3
2) Connections ........................................................................................................... 3
3) Specifications......................................................................................................... 4
4) Power ...................................................................................................................... 5
5) Signal Connections................................................................................................ 5
6) Keyboard ................................................................................................................ 5
7) Operation ................................................................................................................ 6
8) Macros .................................................................................................................... 7
9) Configuration Menu ............................................................................................... 8
10) Updating Modem Software .............................................................................. 10
11) Tips & Techniques, and “Things to Watch Out For” ..................................... 12
12) Technical Support ............................................................................................ 13
Appendix A: The Radio Cable ................................................................................... 14
Appendix B: Schematic ............................................................................................. 15
Appendix C: Release Notes....................................................................................... 16
VERSION HISTORY
The version number of this manual corresponds to the software version running in the
modem. This version number is displayed in the display’s “splash screen” when the
modem is initially turned on.
Version 1.15 – Initial product introduction release.
Version 1.20 – Software update to provide improvements in speed tuning, F10 for Tx
mode, Ctrl-S char, backspace and CWID fixes, and improved displaying/saving/loading
of configurable modem settings.
Version 1.30c – Current software release, providing initial support for the optional USB
add-on hardware and improved text entry keyboard sequences and commands.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 3 Copyright 2008, American QRP Club
1) Introduction
PSK31 is one of the latest communications modes to capture the interest of hams
worldwide. Its inherent ability to dig out weak, nearly-inaudible signals is ideally suited
for low power QRP enthusiasts. The PSK31 digital modem engine, however, requires
intense DSP processing that is only commonly available in PC sound card. Thus the
PSK operator desiring portability for field operation is locked into using a laptop
computer as a controller, which results in a cumbersome station. But there’s hope!
The NUE-PSK Digital Modem offers a unique way for hams to get on the air using the
digital modes. No PC is required, thus enabling one to communicate using PSK31. This
self-contained, hand-held modem connects to your SSB transceiver and allows you
send and receive text data using the PSK31 digital mode.
PSK31 is actually one-of-many modulation techniques within the “phase shift keying”
family of communication. PSK31 operates at 31.25 bits/second, while other speeds may
be achieved using variations to the software algorithm. PSK is perhaps more accurately
termed BPSK, for bi-phase shift keying, whereby two distinct phase states separated by
180 degrees are used to convey the information. Four states may also be
encoded/decoded, as is done with QPSK (quad-phase shift keying), in order to provide
higher speeds with greater error correction ability.
The NUE-PSK digital modem can currently support the digital modes of BPSK and
QPSK, and will soon support MFSK and RTTY. In fact, the field updating capability –
that is, the ability to download new/improved programs from the Internet and simply
program them into the modem – will allow users to stay current with new features and
modes for years to come!
2) Connections
Ideally, you just need to connect up two cables:
a) Connect the modem’s “Radio” cable to the “data” jack on the back of your SSB
transceiver. Most radio manufacturers today provide this way for getting audio
modulated tones to/from the rig.
b) Connect a standard PS2 keyboard, or a PS2/USB combination keyboard, to the
“Kbd” jack on the modem.
You are now ready to rock & roll using PSK31 … read on and enjoy!

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 4 Copyright 2008, American QRP Club
3) Specifications
> Standalone, half-duplex modulator/demodulator for amateur radio digital mode
communications
> Handheld unit ... no PC required
> Menus select operating modes, Squelch Thresh, PGA Gain, CW ID
> 128 x 64 pixel graphic LCD displays audio signal spectrum 500 Hz to 2.5 kHz (with
backlight)
> Tx and Rx buffers and menu system displayed in lower half of LCD using four 20-
character lines of text
> Tune controls modem position along audio spectrum
> Modes currently supported: BPSK31, QPSK, QPSK reversed
> External keyboard jack: 6-pin mini-DIN, PS2-compatible
> Standard PS2-style or dual-mode USB/PS2 keyboard (user-supplied) provides text
input for Tx entry, command/mode selection and modem frequency adjustment
> Connection to SSB transceiver: 8-pin mini-DIN (audio in, audio out, PTT, power)
> Powered by two internal 9V batteries (not included) or an externally-applied supply
via 2.1mm coaxial jack
> Power requirements: 9-18V DC. Current at 12V is 60 ma without backlight, 80 mA
with backlight. The current decreases as input voltage is increased.
> Field reprogrammability of internal microcontroller to allow software updating in the
field by the owner
> Aluminum enclosure provides for rugged portable use while shielding transceiver
from digital EMI
> Enclosure dimensions: 7" x 4" x 1"
> Single 3.75" x 5.25” pc board contains all components and connectors
> Lightweight: < 1 lb with batteries.
> Control for precise audio level control to transceiver
> Cable assembly provided (plug and shielded cable) for connection to the SSB
transceiver
> New in version 1.30c: Optional USB plug-in card provides ability to Record QSO
text and save to USB flash memory device
> Also new in version 1.30c: New text entry sequence for macros.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 5 Copyright 2008, American QRP Club
4) Power
Install two standard 9V alkaline batteries in the battery compartment, or connect a 9 to
18 volt supply to the coaxial power connector (2.1mm) on the right end of the modem.
The two 9V alkaline batteries nestle tightly against the pc board in the compartment.
One battery lies flat and over to one side in the compartment, with the other battery
sitting up at an angle with its connector overlapped with that of the first. The screw-on
cover holds them firmly in place.
Note for version 1.30a … Use of internal batteries is not available when optional USB
card is in place.
5) Signal Connections
Install a connector, or connectors, to the end of the cable which has an 8-pin mini-DIN
connector. Most modern HF rigs have a mini-DIN Data or AUX connector which
provides for PTT, fixed level audio from the receiver (independent of the volume control
on the rig), and a line-level (approx 100mv rms) audio input to the transmitter. On the
Yaesu FT-817/857/897 this connector is a 6-pin mini-DIN. On many Kenwood HF rigs
there are 6-pin and 13 pin mini-DIN connectors that may be used. See Appendix A for
wiring details.
6) Keyboard
The modem requires an AT/PS2 style keyboard for character entry. The keyboard also
provides for entry and playback of macros. Use the 6-pin mini-DIN connector on the
end of the modem to connect to the keyboard. A USB keyboard may be used if it has
built-in PS2 support. Most USB keyboards that are sold with a USB to PS2 adapter will
work, using the adapter.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 6 Copyright 2008, American QRP Club
7) Operation
Once you have the cable between the modem and the rig connected, keyboard
attached, and power available, you are ready to operate PSK. But first, some additional
setup may also be desired, as described next.
Turn on the modem. If the cabling between the rig and modem is wired correctly, you
should see evidence of signals and/or noise on the top half of the display (the spectrum
area). Tune your rig to one of the PSK sub-bands. These are typically 70 to 74 kHz
above the lower band edge on 40 and 20 meters. If there is PSK activity on the band,
you should see peaks on the graphic display. The horizontal location of the peaks
corresponds to the audio frequency of each signal relative to the tuned frequency of the
rig. For example, if the rig is tuned to 14070kHz, the display shows audio frequencies
from 500Hz to 2500Hz, or actual RF frequencies from 14070.5 to 14072.5 kHz.
Now for the fun ... tuning! Turn the encoder clockwise, or counterclockwise, to move
the cursor to a higher, or lower frequency. (The cursor is the small triangular icon just
below the spectrum display.) The audio frequency is displayed when turning the
encoder. Try to align the cursor with one of the peaks on the display. Don’t worry if it is
not exactly aligned. Once close to the peak, stop turning the encoder. The modem now
attempts to “lock” onto the signal and fine-tune the frequency if needed. If the modem is
able to lock onto a PSK signal, it will very shortly begin decoding the signal, and then
display characters on the screen. The time it takes for decoded characters to appear
depends on the ability of the modem to estimate the center frequency of the incoming
signal, and the signal to noise ratio. Tuning can also be done with the arrow keys on
the keyboard. The right and left arrow keys provide finer tuning, while the up and down
arrow keys provide faster tuning. The tuning rate of the encoder on the modem can
also be selected from a menu setting. Note: When tuning in receive mode, the spectral
display is frozen - this is intentional.
Now on to setup for transmission. If you have a dummy load for your rig, connect it
now.
Since PSK signals generated by the modem contain simultaneous multiple frequencies
(over a very narrow bandwidth), it is imperative that the audio output from the modem
not overdrive the input to the rig, or very poor signal quality will result. To facilitate
setting the audio drive to the rig, a potentiometer on the modem may be used to adjust
the level. In addition, the modem includes provision for “measuring” the position of the
potentiometer, so that it can be easily reset to the same setting in the future. More on
this later.
We have found that the best way to set up for PSK operation is to initially set up the
transceiver for normal SSB operation, including whatever power setting you usually
employ. For example, if you have a 100 watt PEP rig, set it up for 100 watts on SSB.
Switch to Digital mode (if your rig provides that option, otherwise retain the SSB mode).
Then press F8 on the keyboard. This places the modem in the TUNE state, which is
denoted by “TUNE” at the top left of the display. The modem is now generating a
continuous tone, which is fed to the audio input of the rig. The PTT signal from the

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 7 Copyright 2008, American QRP Club
modem should also cause the transceiver to switch to Transmit. At this point, the
potentiometer on the modem (just to the right of the display) can be adjusted to set the
power level of the transceiver. A transmit power of 15 to 40 per cent of the rig’s rated
power is recommended. (i.e. 15 to 40 watts with a 100 watt rig). Keeping the power at
this level does two things. First, it minimizes distortion due to clipping. Second, it
avoids excessive heating in the rig finals, since PSK is a 100% duty cycle mode. A
power meter is very handy for making this setting. Once the potentiometer has been
set, press F8 again to return to receive mode.
You should now be ready for transmitting PSK.
Pressing F10 will place the modem in transmit mode, but with a PSK idle tone being
generated (unlike the CW tone in TUNE). If you are ready to give it a try, Press F10. At
this point, anything that you type on the keyboard, will be converted into Varicode
characters and transmitted using PSK modulation. Pressing F10 again, with toggle
back to receive. When in TX mode, “TX” will appear at the top left of the display.
8) Macros
If you want to set up macros (pre-recorded strings of characters for subsequent
playback) before proceeding, now is a good time to do it.
For those already familiar with PSK operations, macro setup is similar to many of the
popular PSK programs.
Macro recording is initiated by pressing Ctrl plus the function key that you want to be
associated with your macro. Let’s go through an example of entering your callsign into
EEPROM memory and setting up a CQ calling sequence, as shown below. (I’ll use my
callsign in this example, but of course you should use your own!.)
a) Record your callsign into EEPROM …
Ctrl-M n2apb Ctrl-Z
b) Record the CQ calling sequence into the F1 macro ….
Ctrl-F1 Ctrl-S cq cq cq de Alt-M k Ctrl-Q Ctrl-Z
Now play the macro by pressing F1 and see …
Tx comes on, “cq cq cq de n2apb k”, Tx turns off
You can also record the other station’s call sign “TheirCall” in RAM (not in nonvolatile
EEPROM) by pressing Ctrl+T, TheirCall and Ctrl-Z to end the entry. To insert the other
station’s call sign into a macro, simply use Alt+T in the macro. Then, when you play the
macro, the other station’s call sign will be inserted into the macro. This way, whenever
you enter a new call sign using Ctrl+T, you do not need to re-record the macro to use
the new call sign.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 8 Copyright 2008, American QRP Club
9) Configuration Menu
Configuration of the modem is done through a menu system. For example, you can
select between PSK, QPSK, and QPSK reversed. You can also change the software
squelch setting, the gain of the programmable gain amplifier (PGA), turn CW
Identification on or off, turn the display backlight on or off, change the tuning
“increment”, monitor battery voltage, or monitor the setting of the TX audio
potentiometer. Other items may be added to the menu at a later time.
The method of menu access is through the “Select” button on the menu and the rotary
encoder. Pressing and holding the Select button for more than ½ second will activate
the menu system. When initially activated, the display will show “Configure” on one line,
followed by “Exit” on the line below. If you wish to abort configuration, simply tap the
Select button at this time. If, on the other hand, you wish to configure one of the modem
settings, simply rotate the encoder clockwise, or counter clockwise, to cycle through the
top level menu selection. Once you see an item that you wish to change, tap the Select
button again. This will then allow you to cycle through a list of choices (again by
rotating the encoder). When the choice you wish to make appears on the display, tap
the Select button again. This will record your choice, and the menu will revert to the top
level, showing “Exit” as the default choice. You can now make additional changes, or
tap the Select button again to exit the Configuration menu.
The current menu choice is the item initially displayed when a given menu is selected.
For example, if you dial up Squelch Threshold menu item and change it to show “25”,
the next time you access this menu item it will still show as “25”, thus allowing you to
always see the current setting before (possibly) changing it.
Another way to see a full “status display” of current settings is to press the F12 key.
This function shows the current value for each of the changeable settings: Mode,
Squelch, CwID, Backlight and PGA. This is a convenient way to determine at a quick
glance how your modem is currently configured.
Once a change is made in Config mode, the display shows “Exit” as a prompt for you to
tap the Select button to get out of Config mode, and once you exit that change will be
effect as long as the modem has power applied. However, you have an opportunity to
save any changed Configuration settings to nonvolatile memory such that those new
settings will be in effect the next time you power up the modem. Just turn the Tune dial
one position counterclockwise and see the option for “Save Config”. Tapping Select at
this point will save the current settings to EEPROM and they will be loaded and put into
effect when you next turn on the modem.
See a useful list of available menus and hot key assignments on the next page, along
with a sample usage scenario for saving data to the USB device.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 9 Copyright 2008, American QRP Club
Hot Keys
F1 to F7 Play Macros
Ctrl-Fn Record Macros-- Enter keystrokes.
Ctrl-Z to conclude entry.
Alt-Fn Delete Macro associated with Fn.
F8 Toggle TUNE mode on/off. Accessible only in RX
or TX. (Not in Setup, or Macro Recording.)
F10 Toggle between RX and TX (but not in Setup,
or Macro Recording)
F11 Display “MyCall” EEPROM.
F12 Toggle on/off a display of modem's current settings.
Ctrl-M Record “MyCall” into EEPROM.
Ctrl-Z to conclude entry.
Ctrl-T Record “TheirCall” into RAM.
Ctrl-Z to conclude entry.
Alt-M Insert “MyCall” into a Macro.
Alt-T Insert “TheirCall” into a Macro.
Ctrl-F Save the current frequency into EEPROM so that it can be restored at the next power-up.
Alt-F Retrieve the saved frequency and makes it the current frequency.
Ctrl-Tab Displays the current frequency (audio)
Ctrl-A Enable AFC (Automatic Frequency Control)
Alt-A Disable AFC (Automatic Frequency Control)
PgUp Increase input gain.
PgDn Decrease input gain.
Ctrl-L Clear the text area of the LCD
Ctrl-K Clear the keyboard buffer. (While receiving, keystrokes are not displayed—this allows clearing
the buffer, so that callsigns may be entered, or re-entered in case you think that you have
entered the wrong callsign)
Ctrl-B Clear the internal buffers
Ctrl-Q Inserts a TX-OFF control character in the TX buffer or Macro. (Toggles back to Rx mode when
encountered in the string being transmitted.)
Ctrl-S Inserts a TX-ON control character in the Tx buffer or macro.
Ctrl-O Toggles the display backlight on and off.
Spectrum Cursor Tuning Rates
Left: 1x: Left Arrow 2x: Down Arrow 5x: ALT+Left Arrow 10x: ALT+Down Arrow
Right: 1x: Right Arrow 2x: Up Arrow 5x: ALT+Right Arrow 10x: ALT+Up Arrow
USB-Related Hot Keys
Ctrl-U: Toggle REC mode on/off. (REC displayed on right edge of display.) REC mode is aborted if no
flash device present in connector. If no USB card detected, the modem’s piezo is beeped after 5 seconds
and REC mode is aborted.
Ctrl-N: Enter name for USB file to be recorded. Ctrl-Z to conclude entry. Standard 8.3 file names
accepted. (E.g., “FD2008-2.txt”)
Ctrl-I: Insert text into recording file. Ctrl-Z to conclude entry. The USB file must already be open (Ctrl-U)
for this to work. The recording file remains open for additional Rx or Tx text, until Ctrl-U pressed again to
close the recording file.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 10 Copyright 2008, American QRP Club
10) Updating Modem Software
Increasingly today, microcontrolled projects have an ability to be “field updated” with
new features and software updates made available by the designers. So, instead of
needing to send your instrument back for re-programming to get these new capabilities
and bug fixes, you can simply download the latest-and-greatest software from the
Internet and send it to the target hardware and the device automatically updates its
internal memory with the new program. What a great way to keep your project
completely up to date with the latest features!
We have incorporated this field updating capability into the NUE-PSK Digital Modem.
You just need to connect your PC serial port to the modem using a simple adapter, and
send it the new software obtained from the NUE-PSK website whenever new
capabilities are made available.
We designed a TTL serial port into the modem, accessible via a 4-pin connector P4
located inside the battery compartment. Just connect your computer’s USB port to an
inexpensive USB-to-TTL adapter such as the CP2102 from SparkFun
9
, plug it into P4
and run the Modem Loader program on the PC. Then pressing the Select button when
turning the modem on will initiate the bootload sequence to “burn” the new software into
the modem’s controller. Once you power-cycle the modem, you’ll be running the latest
software release containing, for example, a new digital mode, some new I/O
capabilities, and so on. This is really quite a convenient and powerful capability for the
project.
Photo 10: CP2102 USB-to-TTL interface from
SparkFun
Figure 5: Schematic of an easy RS-232 interface
to the NUE-PSK Digital Modem

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 11 Copyright 2008, American QRP Club
Loading New Software
In general, the process is simply to power up the modem in a special way with the serial
adapter connected, and then run a program called prog on your PC.
Important ... If you haven't yet proved out your serial adapter connection between
your PC and modem, you should first follow the steps outlined on the web page
Serial Interface Checkout (http://www.nue-psk.com/serial_interface). If you
cannot do the operation specified there, you will not be successful trying to load new
software into the modem.
First, you'll need to "get ready" by first doing a couple of things ...
1) Determine the COM port number of your USB or RS-232 serial port -- You can find
this out by clicking START and then right-clicking My Computer. Select Properties and then
the Hardware tab. Click Device Manager and find the Ports line item in the list. Expand that
line item and see that the Communications Port will have a COM number shown. That is the
serial COM port number that you'll use.
2) Get the PROG program onto your local computer -- You can download prog from
http://www.nue-psk.com/serial_interface/prog.exe. Save the file in a convenient place,
like at the root of your C drive. (When your computer prompts for the save location, enter
C:\ )
3) Download the latest modem software to your computer -- Download the software file
modem1_30c1FP.zip from http://www.nue-psk.com/software/modem1_30c1FP.zip,
unzip the file, and place it in the same location as you did the prog program above.
So, now that you are ready, next perform the following steps to connect the PC to your
modem using your serial port ...
4) Connect the serial interface between the NUE-PSK modem programming port and
the PC -- You will typically need to connect your serial adapter to a serial port cable that is
plugged into your computer, and then connect the adapter to the 4-position "Field
Programming" pinheader (P4) located on the bottom side of the modem pc board, as
accessed form the battery compartment.
5) Open a Command Window on the PC -- You can bring up this window by clicking in
START, Run ... and enter Command. Navigate to where you saved the prog.exe program.
If this was at the root of the C drive, just enter CD \ .
6) Enter command to run the "prog" program -- From the prompt inside the Command
Prompt window, type the following command line ... but do not yet press <Enter>. For
example, on my system that uses COM1 serial port, I would type ....
prog -i com1 modem1_30c1FP.hex
7) Power up the modem in a special way -- Hold down the "Select" button on the Modem,
while turning on the power switch. This commands the modem to look to the serial port for
about 10 seconds before it continues powering on normally. Then quickly, within these 10
seconds of turning on the modem, press the "Enter" key on the PC keyboard to execute the
command you previously entered.
8) See the PC screen start displaying the downloading indicators -- See the PC screen
show a series of "periods" as the software gets downloaded to the modem and burned into
flash. You will see about 3 rows of the periods and then it will stop. At that point the modem

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 12 Copyright 2008, American QRP Club
will automatically restart and you'll see the splash screen display the new version number
"1.30a".
11) Tips & Techniques, and “Things to Watch Out For”
Here is a useful section that will undoubtedly grow in length over time. Please be sure
to often check the NUE-PSK website for the latest online information.
a) Signal Level – Setting the right drive level to your SSB rig is essential to success
when operating the PSK31 mode. Please be sure to read the corresponding
section on the NUE-PSK website containing lots of tips on this topic.
b) Inserting Plugs to the Modem – You will want to be sure that you fuly insert the
Radio and Keyboard plugs into the connectors on the modem. Failure to do so
could well result in unusual, intermittent or “noisy signal” symptoms during usage.
When inserting, be sure to press firmly in the direction of insertion – do not
“wiggle the plug while inserting. Same for unplugging – just pull it back firmly.
(Care in this area will save the life of the connectors on the modem.)
c) Tap-Hold to Select Config – As described elsewhere in this manual, you can
get into the Configuration menu in order to make various settings in your modem.
Config is entered by a press-and-hold of the Select pushbutton … just press the
pushbutton for about one second (say “one one thousand”) and release it to see
the options that you can further select by rotating the Tune control. You can
select any other operation or menu selection merely with a quick tap of Select.
d) Tx Audio Level Setting – This menu selection in Config will show you the
relative position of the mini-pot used for the control on the top of the modem.
The control currently ranges from 0%-to-26%, or -60%, -125% or even -160%,
etc. Don’t worry about the specific number at this time; we will make the
readings more consistent from unit-to-unit in a future software release.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 13 Copyright 2008, American QRP Club
e) Spectrum Artifacts – When viewing a moderately-strong signal at the midscale
point on the modem’s LCD spectrum (which corresponds to 1500 Hz), “noise” will
also be seen on the far right and far left ends of the spectrum display. This is
common and is an artifact of the DSP process of the signal, and it will occur even
when viewing received signals a bit below or above the spectrum midpoint.
f) How We Tested the Modem (in part) – Some might find this info helpful in
testing their own modems. We had direct audio connections to a laptop running
Digipan, with the audio in/out cables connected to the soundcard headphone/mic
connectors, respectively. We then commanded the modem to transmit at 1500
Hz and viewed the classic two-tone “railroad track” signal on the Digipan waterfall
display. Ensuring that the Digipan frequency (i.e., the red diamond) was
centered on the tracks to ensure we were tuned to the modem’s signal, we
adjusted the Tx Audio level control fully counterclockwise to generate no signal,
then increased it slowly in a clockwise direction while viewing the IMD reading on
the Digipan window. We stopped turning the control when the IMD reading got to
a -54 dB level, after which turning it further has no more effect. We found this
level to be an ideal setting of the Tx Audio level delivered by the modem.
Characters typed on the modem keyboard could then be seen on the Digipan
receive window. We then turned the channel around (i.e., set Digipan to Tx and
the modem to Rx), and saw n the modem display the characters typed into
Digipan. [Note, you should follow the adjustment procedure elsewhere in this
manual when connected to a radio.]
12) Technical Support
In case of questions or problems, feel free to send an email with your comments to us at
[e-mail].
Be sure to also check the NUE-PSK website at www.nue-psk.com for the latest
information, software availability and tips & techniques to make your digital mode
operating experience enjoyable. This printed manual will be updated frequently with
corrections and new capabilities presented in the current software, so be sure to always
check out the website.
Another great source of information and camaraderie with fellow owners of the digital
modem is the NUE-PSK email reflector on Yahoo Groups. If not already signed up for
this great communication forum, go to www.yahoogroups.com and search for the
group called NUE-PSK. You can view all the messages posted there, and if you join (for
free!), you will be able to post questions and comments yourself, as well as access the
files in the group.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 14 Copyright 2008, American QRP Club
Appendix A: The Radio Cable
This diagram represents what is shipped with your NUE-PSK modem. Since the
modem can interface with literally hundreds of different SSB transceivers, it will be
necessary for you to connect the “unfinished end” of the Radio cable to properly
interface with your specific radio. Once you have the proper connector in hand for your
radio, the task is simple – just use the signal names and wire colors here as a guide to
get the PTT signal and audio tones to your rig.
The cable supplied with the modem has color-coded wires on one end, either as shown
in Figure A or in Figure B below. You will need to determine which type you have
before attaching the connector required for the data connection to your specific radio.
You can easily determine which cable type you have by using a VOM to check for
continuity from pin 8 on the molded Radio plug to the blue wire on the other end of the
cable. If there is continuity, you have Cable Type A. Otherwise, with pin 8 continuity to
the black wire, you have Cable Type B
OR …
To help owners get on the air as quickly as possible with their new modems, we have
pre-fab cables, supporting over 50 popular transceiver models, available for purchase
from the NUE-PSK website. See www.nue-psk.com for details.

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 15 Copyright 2008, American QRP Club
Appendix B: Schematic

NUE-PSK Digital Modem Operator’s Manual, ver 1.30c 16 Copyright 2008, American QRP Club
Appendix C: Release Notes
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v1.30a Release Notes
October 3, 2008
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1. We have implemented a "Buffered Text Capture" routine, used for capturing MyCall, TheirCall,
FileName, InsertText, and Macros.
a. For entering and storing MyCall … Ctrl-M opens the dialog. The callsign is entered. Ctrl-Z
closes the routine and stores the callsign in EEPROM.
b. For entering and storing TheirCall … Ctrl-T opens the dialog. The callsign is entered. Ctrl-Z
closes and stores their call in RAM.
c. For extering a file Name for the USB Flash Drive file … Ctrl-N opens the dialog, a filename is
entered (standard 8.3 format). Ctrl-Z closes and stores the filename in EEPROM.
d. Macros are recorded as before using Ctrl-Fn, but now the text entry is terminated with Ctrl-
Z. (F9 is no longer used for macro input completion.)
2. A piezo "BEEP" is generated to provide warning alerts for text entry. For example, a beep sounds if
"too many characters have been entered into a callsign".
3. Ctrl-U toggles recording on/off to the Flash Drive. REC is vertically displayed at the right side of the
LCD while in Record mode. Recording is aborted if no Flash Drive is detected. If no USB expansion
card is present, the Ctrl-U function aborts immediately with a Beep of the piezo. If the USB card is
present, but the USB device is not, the function aborts after five seconds with Beep.
4. "On Screen" Insertion of a block of text may be made to the currently open Flash Drive file. For
Inserting text into the recording file … Ctrl-I opens the dialog, Text is entered, and Ctrl-Z closes the
routine and enters the text into the recording file. The recording file must already be open (Ctrl-U) for
this to work. The recording file is left open for receiving text, until the Ctrl-U is pressed again to close
the recording file. This capability is provided for convenient identification of the resultant recorded
data on the USB device. (For example, placing a date/time, operator name, or operating location is a
common use.)
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