Category Archives: Time of Flight

New Stuff, RX-888, SDR, Time of Flight, Uncategorized

Time of Flight Presentation – HamSCI 2026 Workshop

Here is my Time of Flight presentation, where I describe the addition of the time domain to the suite of precision measurements delivered by the wsprdaemon system:

Discussing the TAPRX-888 SDR design — This is a TAPR project that I am working on, creating the schematic and layout package for a true open-source SDR:

More presentations from the HamSCI 2026 Workshop:

https://www.youtube.com/@ARRLHQ

Upcoming: Hamvention 2026 — I will be presenting an update on the Time of Flight systems, including details on the implementation of a time-stamped transmit beacon. If you miss the presentation, please stop the TAPR and HamSCI tables and say hello!

New Stuff, RX-888, SDR, Time of Flight

Time of Flight Measurements

Here’s a preview of a product in development, designed to add Time of Arrival and Time of Flight measurement capability to the RX-888 SDR as used in the wsprdaemon network:

Yes, it’s another Blue Box from Turn Island Systems. This “TS1” generates a carrier signal modulated by the Pulse per Second output of a GPS receiver module, and sends it to the HF input of the RX-888:

With the TS1 and using an enhanced version of ka9q-radio software we have been able to measure the Time of Arrival of (for example) WWV transmissions with microsecond accuracy. A prototype of this unit has been running at the Boulder Colorado WW0WWV site (located on the grounds of the WWV transmitters), and the version shown above at the KPH receiver site on the Point Reyes peninsula in northern California.

We expect that this new measurement capability will be very useful in the development and evaluation of propagation models.

This is a work in progress, but look here if you would like to see some early documentation:

TimeSync 1Download

I gave a presentation on this topic at the 2026 HamSCI workshop (March 14-15):

https://hamsci.org/hamsci2026

The presentations will be available (probably before the Dayton Hamvention in May), see the HamSCI website for details.

Here is my presentation in pdf format:

HamSCI Time of Flight 3Download