WSPR shows open paths on the HF bands

At our 16 February meeting, James ZL2ET gave us an interesting talk on WSPR (pronounced “whisper”) and its applications.

Doug ZL2AOV summarised it as:

“James ZL2ET discussed the challenges and possibilities involved in low-power, very low-speed propagation testing. WSPR (Weak Signal Propagation Reporter) is a computer-driven way to find out which bands are open, when and between what sites; it correlates this data and provides it on-screen.

“Using a presentation prepared by Steve Nichols G0KYA, James took us through the equipment needed: a computer with a sound-card to generate the slow-speed FSK used, a transceiver with accurate and stable frequency control, a source of accurate time (propagation paths are found by comparing accurate time slots of data), and an internet link to upload the data to a central repository for automatic analysis and dissemination. Viewers can see what’s going on by pointing their web browsers at The files can be analysed by band, time, and even by transmitter source … allowing insights into amateur radio DX prospects.

“Transmitters don’t want to be high-powered (maximum five watts is fine) and milliwatts is possible. A Raspberry Pi model B can be programmed to provide FSK on a preferred frequency at about 10 milliwatts out; an amp can push that to 100milliwatts and a tiny bandpass filter does the rest. Timing accuracy can be guaranteed using a wi-fi usb stick to synch to external clocks.

“The protocol provides for transmission of callsign, locator square, power output (in dBm) for 100 seconds, then listening for 120 seconds. Transmission is FSK, just six Hertz.

“The designer of it all? Professor Joe Taylor K1JT, well known for other innovations in digital modes. The system’s sensitivity is stated to be between 11dB and 15dB better than the human ear. That’s way better than using PSK31 and searching for the characteristic double-lines in the waterfall display!!!!”

October Meeting: Blackwood Cup

Blackwood CupIt was Blackwood Cup time again on Wednesday 21 October. Four members brought along home brew projects they had completed over the last 12 months and gave a brief talk on them.   John ZL2HD somewhat surprised himself by winning the competition, and taking away the cup.   Of course the winner gets to go and get the engraving put on the cup base!

John’s construction was a clock inspired by a clock he acquired from the estate of the late Bill Hamer ZL2CD.  However, this one is controlled within microseconds of the real atomic time and sources its time via an arduino and a GPS chip.   In a sign of the times, most of the project time was spent in writing the Arduino “sketch” or program that controls the clock.  Well done John!

The runner up in the competition was Col ZL2COL who produced a rugged lightweight box for his FT857, power supply, tuner and other bits and pieces, including a swivel out light for the portable shack!   This was put to the test on the South Coast at Karori Rock Lighthouse in the International Lighthouse Contest.

Other entries included James ZL2ET application of a Raspberry Pi to a miniature transmitter deployed on WSPR service.  Don’t know what that is?  Then come along to the February meeting to receive a full explanation and to see it demonstrated!

Ted ZL2TB showed us a very well constructed home brew interface between his rig and the sound card in his computer.   No RF in the computer with that one!

The fact that we are still getting a muster of entrants every year means Wellington branch members and still doing some home construction!