Home Page of James C. Ahlstrom

Personal

I live at 221 Pleasant Plains Road, Stirling, New Jersey 07980 USA with my wife Susan. We have two children, Jennifer and Michael. My main sports are birding and skiing. I also enjoy cooking. I am an exercise junkie, and work out at the gym nearly every day. I retired from Interet Corporation on January 1, 2012.

For questions about the Hermes Lite 2, post to this group: https://groups.google.com/g/hermes-lite

For questions about Quisk or the HiQSDR, post to this group: https://groups.io/g/n2adr-sdr

You can email to this address.

Quisk Software

QUISK is a software defined radio receiver and transmitter that runs on a PC. It works with sound card samples, the Hermes Lite 2, the SDR-IQ by RfSpace, and with Ethernet/UDP samples from my SDR transceiver. I use QUISK as my ham transceiver. Quisk is extensible using the Python or C programming languages to make a complete station control solution. It can be used with different hardware by adding hardware and widget files written in the Python language.

I wrote my Quisk SDR software back in 2008, and I have been maintaining it ever since. It has evolved into a capable SDR and remains open source. For questions and support, please visit the group https://groups.io/g/n2adr-sdr.

Ben Cahill, AC2YD has contributed software to run Quisk remotely over a slow network connection. His software is included with the Quisk distribution. His paper has some valuable information especially about running over WiFi.

FreeDV Digital Voice

Quisk has built-in support for the FreeDV project. See https://freedv.org/. Now there is a new and exciting Radio Autoencoder (RADE) in development. It combines machine learning with classical DSP to send high quality speech over HF radio at SNRs as low as -2dB. The speech signal has an audio bandwidth of 8kHz, but the RADE V1 signal requires just 1500Hz of RF bandwidth. The peak to average power ratio is less than 1dB, allowing efficient use of transmitter power amplifiers. It is a new project and I have written a simplified guide to installing and using RADE.

Hermes Lite 2 SDR

I am active in the Hermes Lite project. Steve Haynal, KF7O, and a group of interested amateur radio operators have developed a direct sampling Software Defined Radio transceiver, the Hermes Lite 2 (HL2). The clock is 76.8 million samples per second, and the bit depth is 12 bits for both transmit and receive. The radio is on a 10cm x 10cm printed circuit board and features both low power and 5 watt RF output. The connection to the controlling PC is via gigabit Ethernet. Low cost is a primary objective, and the project is based on an AD9866 digital modem chip. This is a great project that will bring low cost SDR to everyone.

The HL2 requires transmit filters if it is connected to an antenna. I designed a filter board for the Hermes Lite 2 so the 5 watt output can be used as a QRP rig. My filter board is 5x10 cm, and fits in the standard enclosure. It is completely controlled by the HL2.

I designed an Input/Output board for the Hermes Lite 2. It is used to select bands on an attached power amp and to switch antennas located with the HL2. This project is a 5 by 10 cm printed circuit board and related firmware. The board mounts in the same box as the Hermes Lite 2. It mounts above the N2ADR filter board if one is installed. The filter board and the IO board are independent of each other. The PC running the SDR software sends the transmit frequency to the board. The microcontroller on the board then uses the board's switches to control an amplifier, switch antenns or transverters, etc. There are a variety of IO resources available and there will be different microcontroller software for each application. The IO board is meant to be a general purpose solution to control hardware attached to the HL2.

I wrote a program to connect an HL2 to a WiFi network. The software runs on a Linux single board computer such as a Raspberry Pi. One side of the Raspberry Pi connects to the WiFi network and to the PC radio software. The other side connects by an Ethernet cable to the HL2. Data sent from the HL2 to the PC is copied from Ethernet to WiFi. The transmit samples sent from the PC to the HL2 are saved in a large buffer and are fed to the HL2 at a constant rate. The large buffer smooths out the jitter in the WiFi network.

I also wrote a simple program to set the bias on the 5 watt output transistors. But check for a newer version on the project page.

There may be Hermes Lite 2 hardware available from Makerfabs.com. Search for "Hermes".

Ham Radio Station

I got my first Amateur Radio license as a teenager. Amateur radio operators are licensed in the U.S. by the FCC to operate radio transmitters. We "hams" use our stations to chat with other hams around the country and around the world. My teenage license expired when I got busy with college. I got re-licensed later, but that license expired when I was raising my kids. In 2006 I got my most recent license, and I got my old call back, N2ADR.

I am interested in digital radio and Software Defined Radio (SDR). There is a lot of activity in this area. My home station is a homebrew SDR transmitter and receiver. The hardware is my own design, and the software runs on a Windows or Linux PC. It is the only transceiver I have. The only commercial radios I own are an AOR AR8600 receiver and a handheld Yaesu VX-6. The hardware design files and the software for my transceiver are available on this site.

Other Hardware Projects

I first taught myself electronics as a teenager. I used tubes (valves), and I remember how excited I was to get my first transistor, a CK722. Since than, tubes were replaced by transistors, and transistors by integrated circuits. Opamps barely worked at audio, but now they can do 100 MHz. Electronics changes, and I lost track of how many times I relearned it.

I use KiCad and Eagle to design printed circuit boards. I have given up using pre-sensitized photographic PCB material. Instead I have boards made by OshPark. I prefer surface mount devices because I do not have to drill the holes. It is faster to solder them, and the zero lead length makes the RF design more robust.

How to Connect a Key to a PC: Here are some circuits for connecting keys and switches to a PC using a USB to serial port adapter or a microcontroller.
SSB/CW Transceiver: My SSB and CW transceiver is my current Ham Radio station. It is based on an FPGA surrounded by an Ethernet controller, an ADC and two DAC's. The receiver digitizes the antenna voltage, and the transmitter uses direct digital conversion to RF. There are no analog mixers. This project was published in QEX magazine in the Jan/Feb 2011 issue. An improved version called the HiQSDR is available as a kit or a completed unit.
SSB/CW Exciter: My SSB and CW exciter is also based on an FPGA. The design is entirely digital. The output is generated by a DAC and there are no analog mixers. For SSB, audio data from the PC is sent to the exciter using Ethernet. For CW, the key connects to the hardware, the FPGA provides a shaped carrier at the output frequency, and the PC is only used to provide a sidetone. This project was published in QEX magazine in the May/June 2008 issue.

Other Software Projects and Papers

I am an amateur at electronics, but a professional computer programmer. My main computer languages are Python, C and Fortran (yes, Fortran 77). I can manage some Verilog, Atmel AVR assembly language, C++ and several Unix mini-languages. I am a big fan of the Python language, please check it out. Python is an easy to use programming language with advanced features like classes and structured exception handling. It is mature, powerful, practical and free. It runs on Windows, Linux, Unix, Macintosh and other systems.

SDR: This paper explains what a software defined radio is, and why it may be easier to homebrew an SDR than an analog radio.
Hamlib and SDR: This paper discusses radio control software in the context of an SDR. It explains why the control software must connect to the SDR software, not to the hardware.
Phase Corrections: A discussion of amplitude and phase corrections for analog quadrature mixers.
Alsa Names: A discussion of Alsa names and device indexes, and how to specify a certain device. The Alsa names are the names of sound card devices on Linux computers.
ft245: The ft245 is a serial to USB device driver for Linux. It can be used to connect the SDR-IQ hardware to a PC running Linux. It is faster than the standard driver, but that may not be important with today's faster PCs. But the installation instructions are still of interest.
AT-200PC: The AT-200PC is an antenna tuner by LDG Electronics that is controlled by the serial port, and is ideal for a PC-controlled radio. This is control software for the AT-200PC.
PCR-1000: This is control software for an Icom PCR-1000, a pc-controlled radio receiver.
QUISK VNA: Quisk VNA is a vector network analyzer that works with the HiQSDR and other hardware capable of full duplex operation. But there are now many inexpensive VNA devices available and it is obsolete. Support for it was removed from Hermes Lite 2.

Jim Ahlstrom