About the KFS WebSDR Server

Technical details of the server system:

The KFS WebSDR HF radio server system is located near the mouth of Lobitos Creek on the Pacific coast, six miles south of Half Moon Bay, California, USA. This RF quiet location, on a 150 foot cliff overlooking the Pacific Ocean, is in maidenhead grid square CM87tj02; the geographic coordinates are 37° 23' 6'' North, 122° 24' 45'' West. You can easily locate the site using Google Maps or Google Earth by searching for KFS WebSDR.

The 200 acre facility was established in 1933 by the Mackay Radio and Telegraph Co. as the receive site for maritime radio station KFS. (The transmit site for KFS was in the Palo Alto baylands.) The International Telephone and Telegraph Company (ITT) subsequently purchased the station and operated it for many years. In 1995 it became the central control and west coast receive site for the Globe Wireless worldwide HF network serving commercial ships at sea with email and data services. The site is also in use by HF radio providers serving the areonautical and emergency response communities.

The system receivers are connected to a TCI Model 530 Log-Periodic Antenna (omni, 6 dB gain, 2-30 MHz). Pictures of the antennas, courtesy of Hal, KK6HY, are here. Four custom Softrock Ensemble RX III HF SDR receivers from Tony, KB8YIG at FiveDash Inc are packaged in a custom rackmount enclosure. The I/Q data streams from the Softrock receivers are decoded by two Asus Zonar U7 sound cards (for 30M & 75M) and two Asus Zonar U5 sound cards (for 60M & 160M). The other bands (40cw, 40ph and 20M) use FiFi SDR receivers with internal sound card chips. The computer is a TP43E Combo motherboard with 4 MB of RAM, and a 512 GB hard drive; it uses the Debian Linux operating system. The Internet service provider is Coastside.net in Half Moon Bay. Antenna and rack space facilities are provided as a public service by Globe Wireless Radio Services. WebSDR server software was written and is maintained by Dr. Pieter-Tjerk de Boer, PA3FWM. Peter maintains a list of active WebSDR servers and a FAQ page.

To view the system maintenance log, click here. The system operator (Sysop), Craig, W6DRZ greatly appreciates the technical assistance provided by Bob KO6AQ, Steve W7RNA, Paul W7JVY, Hal KK6HY, and Ken WB6CNI. Also appreciated are the donations by many users. Comments and questions are always welcome. Please email Craig.


This WebSDR system is provided as a community service by Palomar Park Radio. Your contribution will help offset our operational costs.
Any support is appreciated. Thanks & 73, Craig, W6DRZ


Tips for using the KFS WebSDR server:

- Newer browsers with HTML5 support like Chrome, Edge, Firefox, Opera will work best. Older browsers including Internet Explorer need both Java and JavaScript enabled for WebSDR to work properly. For details, click here.

- You can specify the startup frequency and mode in the URL when linking to the KFS WebSDR. Use the ?tune= parameter, for instance http://69.24.184.62:8901/?tune=7293am to listen to 7293 kHz in AM (40M AM window).

- Please enter your call sign or name in the box near the top; do not add additional comments. Both the logbook and user display will be much more informative.

- The orange frequency system labels under the waterfall change twice a day, and are different on weekends, to keep them timely. Suggestions for additions and changes are welcome.

- In addition to the above, you can add custom memory labels (green) that save your frequency, mode, and bandwidth settings.

- Click on any label to tune to that frequency and mode, or just click on the frequency scale. You can drag the waterfall with your mouse; the mouse wheel zooms in and out.

- Note that the waterfall view also offers a spectrum (panadapter) display, select it in the View: dropdown box.

- Are the waterfall labels missing, or wrong? An easy fix is to click on the very right end of the active waterfall.

- West coast users may want to try the W7RNA WebSDR in Sedona, AZ as an alternate system for certain signals.

- If the page appears to freeze, I may have had to restart the WebSDR server. Just hit refresh on your browser to resume.

- There is an idle timeout set to sixty minutes. If you don't use the system for that long you will be disconnected.

- To conserve our shared internet bandwidth, one connection per user, please. When you are finished using the system, please disconnect by closing your browser. Thank you.