k1jt's blog

A slightly amended version of WSPR 2.11, with the FMT package, has been posted on the WSJT Home Page.

Direct links are as follows:



There are two significant changes since r2247:

To all those who expressed interest in my software utilities that can help you make very accurate frequency measurements with your CAT-controlled WSPR setup:

These programs are now included in a new WSPR 2.11 package just posted on the WSJT Home Page:


Especially for new WSPR users, I call attention to the following text from step #7 of the quick-start instructions from the User's Guide:

"Select a desired Tx frequency by double-clicking somewhere in the graphical display area. Available Tx frequencies fall in the range 1400–1600 Hz above the dial frequency. Clicking near the bottom of the graphical area gives a frequency near the lower limit, and clicking near the top puts you near the upper limit."

Do you enjoy making very precise measurements? Have you always wanted to enter the ARRL Frequency Measurement Test (FMT), but held back because you assumed that expensive laboratory equipment must be required?

Appendix C of the WSPR 2.0 User's Guide,
http://www.physics.princeton.edu/pulsar/K1JT/WSPR_2.0_User.pdf ,
explains how to calibrate your WSPR transceiver to an accuracy better than one Hertz using over-the-air standard-frequency signals. Many WSPR users have used this procedure to establish calibration constants for their own radios, resulting in significantly improved frequency accuracies of reported WSPR spots.

About six months ago, I wrote some simple software tools that largely automate the procedure described in Appendix C and extend it to enable measuring the frequencies of unknown test signals. I used it for the ARRL FMT held last April, and my resulting measurements of all seven FMT test signals were within less than 0.3 Hz of the published "true" frequencies. (See http://www.b4h.net/fmt/fmtresults201004.php for results of the April 2010 FMT.) My equipment was very simple: nothing more than my normal WSPR setup, a Kenwood TS-2000 with the software mentioned above. Any CAT-controllable radio would do. I've even tested it with my SoftRock, with excellent results.

The next ARRL Frequency Measuring Test is less than three weeks away: November 11, 2010, starting at 0230 UTC (the evening of Nov 10 in US time zones). Details are in November QST and on the ARRL web site at
http://www.arrl.org/files/file/W1AW/Other%20FMT%20files/FMT.pdf .

If there is significant interest from others who would like to try entering the November 2010 FMT, I'd be happy to write some brief instructions on using the new frequency-measuring software tools, and make them available for free download. It will probably be simplest to just include everything in a packaged release of WSPR 2.1. If you are interested, please let me know (k1jt at arrl dot net).

WSPR 2.1 r2210 is now available for download at:


This version corrects a bug found by LA3JJ, and it controls the SoftRock in the same way that it controls all other radios, by using the hamlib program "rigctl".

IMPORTANT: on the Setup | Station parameters screen, you must select a new Rig number for SoftRock control. Scroll down past the Kenwood entries and select this one:

2509 SoftRock Si570 AVR-USB

As noted here yesterday, the "Tx dB" slider was inadvertently left in a disconnected state in WSPR 2.1 r2206. This omission is corrected in r2207, available at:


I have also updated the "WSPR 2.1: Supplement to User’s Guide". A new version is posted at


Many thanks to all those who tested and reported a bug in WSPR 2.1, r2198. The bug caused Tx image rejection to disappear and re-appear without notice. Very bad!

This problem has been fixed, and WSPR 2.1 r2206 is now posted at:


Changes since r2198:

1. Intermittent Tx phasing bug has been fixed.

2. Added a Help-menu item to call up the WSPR 2.1 Supplement to the User's Guide.

WSPR 2.1 r2198 has been posted at:


Changes since r2194:

1. On some computers, a bug in r2194 caused errors in Tx timing. Although none of my machines exhibited this problem, I believe it has been fixed. Please let me know if not!

2. Negative values of Fiq are now permitted. You can use an LO on the high side of the desired WSPR band.

WSPR 2.1 r2194 has been posted at:


Instead of listing the essential changes since r2179, I direct you to the document "WSPR 2.1: Supplement to User’s Guide" now posted online at


Hi all,

The 3 dB deficiency in signal-to-noise of WSPR 2.10 has been traced and corrected. It was an image-rejection problem: not the image about the SDR's LO frequency, but rather the image about the "digital BFO" converting WSPR signals to audio around 1500 Hz. An easy fix, once I understood what I had done wrong.

If you want to use WSPR 2.1 with 3 dB better Rx sensitivity, you can download it from:


Other changes in r2179, relative to r2165:

1. As many users discovered, the "0 dB" level had been set much too high. It has been re-defined at an appropriate level.

2. I/Q mode setup parameters have been moved from menu item "Setup -> Advanced" to "Setup -> IQ Mode". The checkboxes for "Enable I/Q mode", "Reverse Rx I,Q" and "Reverse Tx I,Q" behave as in previous versions.

3. New controls have been added for "Tx dB", "Tx I/Q Balance", and "Tx Phase". You can use "Tx dB" to reduce the amplitude of Tx audio tones (and thus your Tx output power, assuming a linear transmitter) by a specified number of dB. The Balance and Phase controls are not yet functional, see below.

Still to Come

Because of an overwhelming level of interest, discussion among those testing WSPR 2.1 -- designed for stand-alone operation with the SoftRock RxTx Ensemble and similar SDR transceivers -- has been moved from a private email list to the WSPRnet "Questions and Answers" Forum. See the topic "WSPR 2.1, for I/Q SDRs".

You may still send bug reports to me directly.

-- 73, Joe, K1JT

I am currently experimenting with a WSPR version that controls and operates radios like the SoftRock RxTx Ensemble.

With WSPR 2.1 you can check a box labeled "Enable I/Q mode" on the Advanced Setup screen. The program will then use 2-channel sampling at 48000 Hz for both input and output. Your SoftRock sends its I/Q baseband signal to the computer's soundcard input; the soundcard output, also in I/Q format, goes to the SoftRock's Tx audio port. T/R switching is accomplished over the USB port. You need no other software such as Rocky or PowerSDR, and there's no need for anything like Virtual Audio Cables. Setup is extremely simple.

Over the past several days I've been running an early version of WSPR 2.1, in Rx-only mode. Right now I'm running in Tx-only mode, Txing 33% of the time, on 30 meters. It seems to get out well. I'll probably finish the T/R switching code and be in full operation within a day or so.

Thanks to Giorgio, IK1UWL, an Italian translation of the WSPR 2.0 User's Guide is now available. A link has been placed on the WSJT/WSPR web site:


... or you may click on a direct link to the Italian version,


Thanks to Nobuyuki Oba, JA7UDE, a Japanese translation of the WSPR 2.0 User's Guide is now available. A link has been placed on the WSJT/WSPR web site:


... or you may click on a direct link to the Japanese version,


This is an embarrassment of riches, caused by my own poor memory.

In addition to the one mentioned in my announcement a few minutes ago,
a German translation of the WSPR 2.0 User's Guide has also been prepared by Klaus Korn, DJ6LB.

I apologize to both Klaus and Ray, DL3LST, for encouraging them both to work on this task without either one knowing that the other has been given the go-ahead. (As it happens, Karl Schmidt, DK5EC, also volunteered -- and I did remember to tell Karl that a translation was already underway.)