W3PM's blog

This is an inexpensive project based around a partially built $21 SoftRock Lite II receiver and an $8 Si5351A module. The transceiver provides single band operation between 630 and 10 meters. There are many transceivers in the marketplace that provide good performance at a reasonable cost. However, I enjoy building and experimenting, so I documented this project to share with those who have similar interests. Additional information is located at: http://www.knology.net/~gmarcus

Gene W3PM

Perhaps in the future there will be an I/Q processing feature in WSJT-X. Until that time, I chose to use a dual op-amp I/Q signal processor. I documented this project to share with those in the WSPR community who enjoy building and experimenting. The project is located at: http://www.knology.net/~gmarcus/

Gene W3PM

The SoftRock Lite II for 455 kHz IF operation provides an inexpensive but effective way to monitor WSPR activity on 630m. The receiver kit cost $23 USD from fivedash.com. This is a software defined receiver that uses a 464 kHz local oscillator. After building the kit, measure the actual local oscillator frequency. In my receiver it was 463.936 kHz. Subtract the actual local oscillator frequency from the WSPR dial frequency of 474.200 kHz. Using a I/Q compatible program such as WSPR 2.12 or Linux WSPR 4.0 open Setup > I/Q Mode.

W4ATV is an experimental solar powered sub-mW WSPR beacon located in Madison, Alabama (EM64). It is capable of outputting either 1000, 500, 250, or 85 uW on 30m. Power output was verified using a calibrated HP-432A power meter and GIL-360-2 bolometer mount. The antenna is 5.5m vertical with 24 1/4 wavelength buried radials. An antenna with a higher radiation angle would probably produce more spots.

This project provides a simple means of generating an audio WSPR signal using either an Arduino Nano or Arduino Uno to drive a SSB transmitter for mobile or portable WSPR beaconing. Automatic compound callsign and GPS derived 6 digit locator encoding are included.

Additional information is at: http://www.knology.net/~gmarcus/

73, Gene

I have placed a self-contained utility that, in one go, will generate a text file for use with PIC assemblers. The utility will generate either conventional callsign/4 digit locator or compound callsign/6 digit locator data. Additional information is at http://www.knology.net/~gmarcus/.

Gene W3PM

This project was updated to include GPS derived frequency calibration and compound callsign/6 digit locator capability. Additional information is at http://www.knology.net/~gmarcus/.

Gene W3PM

I have created an Arduino Uno version of the Arduino Mega/DDS-60 project. This project retains many of the Mega features but uses less hardware. What may be of particular interest to QRSS users is the option to select 1 of 12 different graphical patterns to append to the ID.

The Mega project was also updated to include individual WSPR power allocations to each band/timeslot and 12 QRSS graphical patterns.

The projects are located at http://www.knology.net/~gmarcus/.

73,

Gene W3PM

I have recently completed a WSPR/QRSS beacon project using an Arduino Mega and DDS-60 signal source.

The PIC-EL is a PIC project/demonstration board described in the February, 2010 QST. The PIC-EL in combination with the DDS-60 daughter board make a nice multiband QRPp WSPR transmitter.

A modified version of AA0ZZ’s excellent signal generator program to include WSPR operation is located at http://www.knology.net/~gmarcus/. Capabilities include 160 – 6 meter operation, LCD readout, internal timing, VFO control, and a frequency calibration routine in software.

The PIC software for the Audio WSPR Source was updated to include on-chip WSPR message generation. On-the-fly grid square location updating for portable operation is also included if GPS timing is used.

The system now has the following capabilities:

I have documented my most recent project that allows a portable SSB QRP transceiver to transmit WSPR beacons from a portable location without a computer.

The project consists of a simple audio oscillator controlled by a Microchip 16F628 PIC that has the following capabilities:

- Internal timing or NMEA GPS timing for UTC synchronization of WSPR transmissions.
- RS232 input of the WSPR message.
- Line or microphone output.
- Symbol data output available to modulate a VXCO
- Low power consumption allowing battery operation

During the last few days, I have been experimenting on 30 meters with output powers as low as 20 microwatts. No one has spotted my 20 microwatt signal yet, but K8CXM has spotted my 50 microwatt signal at a distance of 553 KM at 2332UTC, 05 AUG 09.

A 100 mW beacon with a step attenuator to an indoor doublet was used for all the tests. All equipment is homebrew and the output power is verified with a HP-432A Power Meter. If you look in the database the power is reported as 0.100 watt because it was too difficult to pull out and reprogram the beacon’s PIC controller chip for each change of power. In any case, there are no provisions to report power levels below 1 milliwatt to the WSPR database.

Other noteworthy spots:
100 uW - K8CXM, 2252UTC, 05 AUG 09, -23 dB, 553 KM
200 uW - AI4SA, 0530 UTC, 02 AUG 09, -21 dB, 333 KM
500 uW - NJ0U, multiple spots 31 JUL & 01 AUG 09, -28 dB to -20 dB, 716 KM
500 uW - K1JT, 1440 UTC, 31 JUL 09, -21 dB, 1215 KM
500 uW - W3HH, 1240 UTC, 31 JUL 09, -28 dB, 764 KM
5 mW – VK6DI, 2232 UTC, 05 DEC 08, -27 dB. 17,858 KM