AmQRP products supplied by MIdnight Design Solutions

NUE-PSK Digital Modem

A digital modem for PSK31 field operation ... without using a PC!

  
 
Learn more about the NUE-PSK and digital mode communications from modem owners ...
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  ARTICLES OF INTEREST

Loading the Latest Software

Making the Serial Cable

Using the USB Card

ICD2 Programming Cable
for Software Developers

Notes for Kit Builders

Battery Life Study

Odd Keyboard Behavior?

HC908 Programmer for U5

Frequently Asked Questions

PHOTO GALLERY


Try out the IW7EHC "Menu Reference Label"
 Just print, cut it out and paste to the top of your modem!
 (Click for larger view)


System connections on the side panel
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PC board holds all components
Connection of LCD-to-motherboard in production units is accomplished using a pre-fab flex-wire strip, instead of the orange wires shown here.)
(Click for larger view)


Production PCB
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Production PCB
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Highly-trained and seasoned designer checkout at the factory (W8NUE)
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"Did I actually order the wrong-sized screws?!" (N2APB)
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Cover of QEX for Mar-Apr 2008
Read the entire 12-page article here.


Portable PSK31 station:
(top) Transceiver (FT-817)
(middle) NUE-PSK Modem
(bottom) "2366" Keyboard
(Click for larger view)


80m Warbler + NUE-PSK Modem station:
(top right) Warbler 80m PSK31 Transceiver
(top left) NUE-PSK Digital Modem
(bottom) Dauphin PS2 mini-keyboard
(Click for larger view)

 

Featured in QST for March 2008
Featured in QEX for Mar-Apr 2008
Winner of Circuit Cellar Magazine's "Design Contest 2007"
Featured in new ARRL CD: "Digital Technology for Emergency Communicatrions Course

NUE-PSK Digital Modem

An easy and portable way to get on the air with PSK-31 ... no computer required!

    The NUE-PSK is a small 7" x 4" x 1" standalone, battery-operated digital modem using a graphic display for transmit and receive text data, as well as for showing band spectrum and tuning. Just plug in a standard PS2 keyboard and connect to an SSB-capable transceiver like the FT-817 or the PSK-xx transceivers from Small Wonder Labs, and you'll have an effective digital mode station that goes absolutely anywhere.

    The NUE-PSK modem is an "open" design, with published hardware details and software source code.  What this means is that over time many others can contribute to the modem's capabilities and modes of operation.  Already we have a "USB add-on option" that allows one to record the QSO to a USB stick for archival or EmComm use. 

    Further, the modem has the ability to be "field upgraded" by using a serial port (or USB thumb drive) to load new versions of the modem software.  Just download the latest-and-greatest modem software from this website and send it to the modem over the serial port.  It's the modem that keeps on growing ... new modes, new features, new add-on accessories!

  Summer Sale!    Order Page  Summer Sale!
One-stop location for ordering modems, cables, USB cards and manuals.

USB Add-On Card
Records QSOs to a USB flash memory device, and loads new modem software from a USB thumb drive or from a computer.

MODEM NEWS
Updated:  June 21, 2009

Product Shipments ...    
> Summer Sale prices are now in effect ... Happy Summer!
> RTTY receive is now supported in the latest software, v2.0a. 
> Everything is in stock.  We ship everything within 7 days of receiving your order, and oftentimes sooner!
> RTTY mode is here! — Milt has RTTY receive working really nice and we're introducing it in v2.0a.  See notes in "Latest Modem Software" section directly below.
> Modem Configuration Utility — George has been working on a new function to allow save/load of the modem’s configuration parameters to/from the PC over the serial port or USB thumb drive.  This would allow the modems’ various modes, settings, and macro strings to be entered to a text file on the PC for easy modification and storage, and then it could be downloaded to the modem.  Should be ready this summer.
> “NUE-SDR” ... an SDR transceiver option for the NUE-PSK Modem — This newest hardware option for the modem has been in development for the past five months by a small team and we showed off the prototype over the weekend at FDIM and at the Dayton Hamvention.  The NUE-SDR is a standalone transceiver consisting of a DSP control board coupled with a the RXTX v6.3 Softrock, both contained in a separate cabinet the same size as the PSK modem.  Designed to be attached beneath the PSK modem box, and connected to the PSK modem by a short signal cable, the NUE-SDR serves as a 20m QRP transceiver for use with all existing PSK modems.  So now, in addition to no PC being needed for PSK use, there isn’t even a need for a separate transceiver!  This integrated package uses the PSK modem’s graphic LCD spectrum, dial and pushbutton to control the HF transceiver in the lower box to transmit and receive the PSK signals modulated/demodulated in the upper box.  Again, the NUE-SDR is in still only in prototype form, but we are hoping to have product for sale later this summer with a target price in the $200 range (subject to change), and available as a kit or fully assembled and tested.
> CW Mode — Continues to be in development.  Expecting to release software to support this mode this summer.

Latest Modem Software:  Version 2.0a ...
     This latest software release adds support for the RTTY mode.  Milt has been focusing hard on adding our first "new mode" to the modem, and we first have RTTY receive working very nicely!  Just dial up RTTY from the Mode menu in Config, set your rig to USB, and find a RTTY signal on the band with its characteristic double bump seen on the spectrum display. Set the cursor in the middle and watch the RTTY text appear on the display!  See the Release Notes for more details.  Once we all have some good luck using this first implementation of RTTY receive, we'll add the transmit capabilities.  Great going, and thanks Milt!

     So be sure to load the latest software into your modem, and be sure to check out the full set of latest documents in the Technical Resources section below: Release Notes, Command Reference Guide, Source Code, Operator's Manual and the USB Card Manual.
 

Technical Resources

The Latest Software (v2.0a):
- Source Code: dsPIC  MC908 -- All the source code useful for developers
- Full Binaries: dsPIC  MC908

Release Notes

Video Clips:
- Prototype Operation (5 minutes, 47 MB .wmv file)
- Video Clip: Battery Installation  (2.5 minutes, 20 MB .wmv file)

Tips on Installing the Batteries

Articles:
- QST --  March 2008
- QEX --  Mar-Apr 2008
- ARRL/TAPR 2007 Digital Communications Conference -- Article and Slides

Documentation:
- Operator's Manual 1.34 -- The manual describes operation, keyboard macros, and more. 
     - Operator's Manual 1.30
    - Operator's Manual 1.20
    - Operator's Manual v1.10
- QuickStart Guide -- Everyone gets this 1-sheeter with their modem purchase. This is the latest version.
- Command Reference Guide -- A very handy 1-sheet summary of the modem & USB commands
- USB Card Manual -- Complete collection of notes for technical, assembly, programming, installation and use.
- USB Quick Install Guide (1.30c) -- Describes how to install your assembled & tested USB card option
- USB Quick Assembly Guide (1.30c) -- Instructions needed for assembling the USB card option.
- Radio Cable Guide -- How do you connect to your rig?  Cabling details shown for over 50 radios.
- Kit Assy Manual -- This is how you assemble your own modem.
- SDK Manual -- For developers of custom software.

IW7EHC "Menu Reference Label" v1.20 -- (PDF or DOC) -- Just print, cut it out and paste to the top of your modem!

Important Notes:
- Power Supply Modification -- Modems first into production can benefit by applying these simple mods to allow powering the unit from an external supply without removing the batteries.
- Radio Cable Documentation Correction -- See the linked page here for information concerning the 3-foot radio cable supplied with your modem. It is important to understand if you have a Type A or Type B cable so you know how to attach the connector for your SSB rig.
- Supplying Power to/from the Modem -- This is a caution note for use in wiring your own connector for the cable to your transceivers ... be careful how you handle the +V line on the end of your cable.

Overview
PSK31 is one of the latest communications modes to capture the interest of hams worldwide. Its inherent ability to dig out low, near-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 is a standalone, battery-operated digital modem using a Microchip dsPIC33F microcontroller. The project uses a single graphic display showing transmit and receive text data, band spectrum, and tuning indication. When coupled with an SSB-capable transceiver and a standard PS2 keyboard, the NUE-PSK Digital Modem forms an effective, compact, and portable station for working the digial modes on the amateur bands.

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 menuing 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, 80mA 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
 >    Optional USB Card provides ability to record transmit and receive text from QSOs for archival and printing.  Also serves as serial adapter port for connection to PC for upgrading modem software

 

Schematic

As illustrated below, a dsPIC33F is at the heart of the project design. This highly-integrated dsPIC33F device employs a powerful 16-bit architecture that seamlessly integrates the control features of a Microcontroller (MCU) with the computational capabilities of a Digital Signal Processor (DSP). The resulting functionality is ideal for applications that rely on high-speed, repetitive computations, as well as control … just perfect for the NUE-PSK Digital Modem.

A complete description of the NUE-PSK Digital Modem design and operation is provided in our cover article in QEX for March-April 2008.


(Download full-resolution PDF version of the schematic)

Parts List for Homebrewers:

Download BOM as Excel Spreadsheet

User Interface (1.34)

Keyboard 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.)
Shft-F9    Turn on Beacon Mode. ‘BCN’ displayed.
Alt-F9      Turn off Beacon Mode.
F10          Toggle between RX and TX. (Not in Setup, or Macro Recording)
F11          Display “MyCall” from 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 freq and makes it the current freq.
Ctrl-Tab   Display the current frequency (audio)
Ctrl-A      Enable AFC
Alt-A        Disable AFC
PgUp       Increase input gain (PGA)
PgDn       Decrease input gain (PGA)
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
                callsign may be entered, or re-entered in case you think
                that you have entered the wrong callsign.
Ctrl-B      Clears the internal buffers
Ctrl-Q      Inserts a TX-OFF control character in the TX buffer, or Macro.
Ctrl-S      Insert a TX-ON control character in the TX buffer, or Macro
Ctrl-O      Toggles the display backlight on and off.
Ctrl-U      Toggles REC mode on/off for recording text to USB drive.
Ctrl-N      Enter filename to be used for recording text to USB drive.
Ctrl-I       Enter free-form text to be recorded to USB drive.

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.

 

Config Menu:
    Mode: BPSK, QPSK, QPSK/R
    Squelch Threshhold: 25, 50
    CWID:  On, Off
    PGA Gain: x1, x5, x16, x32
    Tune Increment: Single, Double
    Battery Voltage
    TX Audio Level
    Save Config
    Beacon Mode
    PC Bootload
    Flash Bootload
    Exit

 

Example Usage of Recording to USB Device
1) Power up modem (flash mem device not inserted)
2) Enter filename for file to be recorded …
        Ctrl-N  FieldDay.txt  Ctrl-Z
3) Turn on REC mode to begin recording
        Ctrl-U
     and see the USB LED blink fast.
4) Insert block of free form text to Flash filename …
        Ctrl-I   Field Day 2008 QSO recordings  Ctrl-Z
5) Tune around and find a station to call
6) Enter Tx mode per usual (F10) to call.  Entered text is
    recorded to USB filename.
7) Enter Rx  mode per usual (F10) to receive.  Receive
    text is recorded to USB filename.
8) Insert free form text to USB file …
         Ctrl-I  Time ending QSO is 2130 hrs.  Ctrl-Z
9) Close USB file recording session …
         Ctrl-U
      and see the USB LED stop blinking and go solid on.
10) Remove Flash memory device for remote viewing, archival or printing.

 

Example Usage of Keyboard Hot Keys
1) Record MyCall to EEPROM …
        Ctrl-M  n2apb  Ctrl-Z
2) Record CQ sequence into F1 macro …
        Ctrl-F1  Ctrl-S  cq cq cq de Alt-M Ctrl-Q Ctrl-Z
    Play the macro by pressing F1 and see …
        Tx comes on, “cq cq cq de n2apb”, Tx turns off

 

 
   


Page last updated:  June 21, 2009