Category Archives: RX-888

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

FST4W, Power, RX-888, SDR, WSPR

Glitchless Power with the TIS-1250

This is another design inspired by and adapted from a KA7OEI project:

https://ka7oei.blogspot.com/2025/01/a-short-term-ups-for-mini-nuc-type-pcs.html

We’ve seen that that the small computers used in wsprsonde (and other) receive installations will reset or hang up during power outages, even when there is a UPS between the utility power and the computer’s power brick. It turns out that many UPS units have a momentary dropout when they transition to backup mode, and the brick power supplies do not have enough internal storage to ride through this transition. This is bad enough in home operation, but especially problematic in a remote installation with limited access.

There are certainly glitchless UPS products available (“on-line” UPS), but these are more expensive and sometimes “glitchless” really isn’t.

The TIS-1250 provides an alternative solution, by using a “supercapacitor” (1.25 Farads) and low-loss charging / discharging circuitry.

See more details here:

TIS-1250 SuperCap UPS
New Stuff, RX-888, SDR

The TIS-B1 Balun is Now Available

The TIS-B1 Balun converts a 50 Ohm signal to a balanced 100 Ohm impedance as needed when using twisted-pair CAT 5 and CAT 6 ethernet cable.

Ethernet cable is being used in advanced balanced wideband “probe” receive antenna systems, where balance and ground isolation is extremely useful in reducing common-mode interference.  The TIS-B1 Balun can be very useful in developing and testing these antenna systems.

For more information, please see the Users Guide: 
TIS-B1.pdf

To purchase:
https://turnislandsystems.com/product/tis-b1-balun/

New Stuff, RX-888, SDR

Mixed-Signal Digital / RF Testing

I have a new post on my ham blog showing a potential Turn Island product, and how I use the TIS-126 Clock Distribution Buffer and the TIS-5351 TinyClock to solve some test-setup problems:

http://wb6cxc.com/?p=501

The new design is a BPSK modulator to be used to generate an in-band time-sync signal. This signal is injected into the antenna port of a receiver and used in time-of-flight and time-of-reception measurements.

The BPSK modulator can also be used to generate over-the-air signals using NRZI BPSK modulation . I show some test results in the blog.

FST4W, New Stuff, RX-888, SDR, WSPR

New Filter and Filter-Preamp – designed for six-meter operation

This is a new filter, designed for use with preamplified “probe” antennas, and many other receive antenna systems. This includes a bypassable low-frequency shelf filter, and can be jumper-configured for either 30 or 60 MHz low-pass anti-alias filtering.

See more details here: https://turnislandsystems.com/product/f3060-filter-shelf-30-60-mhz-lpf/

And a new 60 MHz Filter-Preamp:

This one has an aggressive low-pass filter, optimized to eliminate 88-108 MHz FM broadcast band signals before they can cause trouble. The high dynamic range preamp provides about +20 dB of low-noise gain.

Details here: https://turnislandsystems.com/product/60-mhz-filter-preamp/

BeaconBlaster, FST4W, RX-888, SDR, WSPR, WSPRSONDE

Hamvention Presentation

Here’s a talk I gave at the Hamvention TAPR Forum on Friday. The first half is about SDRs: dynamic range, signal to noise optimization, filtering, sampling and aliasing, etc. Then I share some details about the WSPRSONDE. I enjoyed presenting this to a (surprisingly) full room.

I hope you find it interesting!

[UPDATE: new video above!]

BeaconBlaster, FST4W, RX-888, SDR, WSPR, WSPRSONDE

Going to the Hamvention!

In partnership with TAPR and HamSCI, Turn Island Systems will be going to next week’s Dayton Hamvention. On Friday I will be giving a TAPR Forum presentation covering the topics:

  • Optimizing wide-band SDR receiver performance
  • Development of a multi-channel research transmitter

(At the moment, the Hamvention website forum details are wrong, we are working on getting this fixed.)

Look for the TAPR and HamSCI tables in Building 5 (Hertz). I will be flying the Turn Island Systems banner there, and will be bringing a bunch of Turn Island Systems products for show and tell.

I look forward to seeing you there!

FST4W, New Stuff, RX-888, SDR, WSPR

SDR Dynamic Range and New Filter Development

Over on my wb6cxc.com blog I have posted about SDR dynamic range and some related Turn Island Systems products that are in the early prototype stage: a Filter-Preamp with a 60 MHz antialias filter optimized for 88-108 MHz FM broadcast band rejection, and a completely new multiband receive filter-bank which (in many cases) will reduce MW and SW broadcast band overload . I hope to have these fine-tuned and available very soon!

I invite you to participate in the development discussion:

SDR Dynamic Range and New Filters

New Stuff, RX-888

Postings on Turn Island groups.io forum

I am starting discussions of our existing products and new developments, and invite you to participate:

https://groups.io/g/TurnIslandSystems

The forum has been quiet for some time, but it’s a good place to make comments, suggestions, critiques, and anything else even slightly related to Turn Island Systems.

And if you have one of our RX-888 Clock Adaptors (now available from TAPR), please share your experience with it — good or bad.