NUE-PSK Digital Modem

Version 5 Operating Manual
Printed booklet once again back in stock (spiral bound with plastic cover) - perfect for the travel bag.
Online PDF version also updated, conveniently combining all four major chapters (Main, CW, Keyer, RTCC)

Available Accessories:
Custom Flash Drive, USB+RTCC card, interface cables, printed manuals

An easy and portable way to get on the air with PSK-31, RTTY and CW ... 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 many others can contribute to the modem's capabilities and modes of operation. Already we have a "USB add-on option" that maintains the current time and date, and lets you record the QSO (with a timestamp) 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. The NUE-PSK Modem supports BPSK (PSK-31), QPSK, RTTY and CW. 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!

MODEM NEWS
Updated: July 28, 2012

> Version 5.02 Software Available ... The sequence of internal releases since introducing Keyer Mode in V5.0 have mostly been correcting subtle errors and making operation more reliable. While v5.02 is not a critical/mandatory release, we do recommend that you perform the software update when convenient, as it will enhance your experience when using your NUE-PSK Digital Modem. (See the Software section on our home page to download the new software to your computer and then load it onto your modem.)

> Version 5 Operating Manual ... Printed booklet once again back in stock (spiral bound with plastic cover) and it has been updated to reflect software version 5.02 capabilities. And in the small form factor it's perfect for the travel bag. See the ordering page to get this. The online PDF version was also also updated, conveniently combining all four major chapters (Main, CW, Keyer, RTCC) into a single document for convenient reference to all the modems features and the latest appendices illustrating the schematics, command reference tables and keyboard codes.

> Parallax Mini-PS2 Keyboard no longer good for use with the NUE-PSK modem! Apparently Parallax changed the vendor for the internal controller chip in this keyboard that we had long-recommended for modem users, and the keyboard no longer reliably works. Timing of the serial signals to/from the keyboard is carefully specified, yet some foreign manufacturers do not pay careful enough attention to the spec and timing falls outside the timing tolerance we have in the modem's keyboard controller. (We had a similar condition when the modem was introduced and we widened our tolerance up to far beyond the specifications, and the modem has worked well with all keyboards (including the Parallax one) for the last 4-5 years. Regrettably, Parallax.com changed their supplier and we must caution modem users against getting this one. Another small and inexpensive keyboard that some have found suitable for portable use with the modem is available from www.Frys.com (product # 5874793) with USB adapter (product # 3470833).

> Summary of recommended hardware mods ... Just a couple mods to the modem pcb are recommended for optimum performance. Easy to do and provides better immunity to external RFI and internal EMI.

> SDR Cube ... an SDR transceiver option that is optimized for digital mode operation with the NUE-PSK Modem � Want another easy way to take your digital mode operation to the field? Check out this companion to the NUE-PSK modem: a portable, Software Defined Radio transceiver that also does not need a PC to work! It's a fully self-contained CW/SSB/AM transceiver with some amazing features that make it great for the digital modes when used with the NUE-PSK.

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.

> Standalone, half-duplex modulator/demodulator for amateur radio digital mode communications

> 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

> 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.

> Aluminum enclosure provides for rugged portable use while shielding transceiver from digital EMI

> 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, and for uploading/editing/downloading file with modem settings and macro text strings.

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.