Grape 2 Personal Space Weather Station

Description and Purpose

The Grape 2 is a three channel, low-IF receiver, operating in portions of the HF (shortwave) bands. It is a key component of the HamSCI Personal Space Weather Station (PSWS). The Grape 2 was designed with a specific purpose in mind: Receiving, analyzing and recording of signals from frequency standard stations such as WWV/H and CHU. The PSWS project involves monitoring changes in the Earth's ionosphere through measurements of signal levels and Doppler frequency shifts on a 24/7 basis.

Anatomy of the Grape 2 PSWS

The Grape 2 is the high performance member of the Grape PSWS family. It is capable of receiving three frequencies simultaneously, utilizing a GPS disciplined oscillator for making precise frequency measurements. The system is designed to receive on 2.5, 5.0, 10.0 or 15.0 MHz. (Operation on CHU frequencies of 3.33, 7.58 and 14.36 MHz is possible with reduced performance.)  A complete Grape 2 PSWS system consists of the following: Grape 2 Receiver and Logic PC boards, Teensy microcontroller, Raspberry Pi 4, external hard drive, power supply and two antennas, one for the GPS and one for the time standard frequencies. Ideally, every Grape 2 should have access to a reasonably fast (>100Mb/S) Internet connection for data uploads. There is a provision to buffer and transmit buffered data at a later time if the connection is lost. Detailed documentation is being developed and will be published here as soon as available.

Please note that the Grape receivers are not general purpose shortwave receivers. They are designed to receive signals only on frequencies pertinent to the research goals.

Data collected by the Grape 2 is intended to be uploaded on a daily basis to a server hosted by the WWV Amateur Radio Club (WWVARC). The data will eventually be made publicly available. For now, researchers may be granted access upon request. E-mail us at and we'll be in contact to discuss the particulars.

Success Story:  Grape 2 Eclipse Monitoring on 8 April, 2024

Approximately 30 Grape 2s were manufactured and tested late in Q1, 2024.  They were deployed in accordance with terms of the grants which funded the project:  A map of the stations appears on this page.    They were on line and uploading data during the April 8, 2024 North American total solar eclipse.  It is expected that they will be kept running, on a 24/7/365 basis, for years to come, studying the behavior of the ionosphere during Cycle 25. 

Further, some Grape 2 installations included remote magnetometer boards, used to measure minute changes in the Earth's magnetic field.  That data was also sent to the WWVARC server.

Grape 2 Documentation

Details on the Grape 2 will be made publicly available once the documentation is complete and checked for accuracy.  Links to the documentation will appear here, on this page.


Images of the Grape 2 under development at the bench of John Gibbons, N8OBJ:



Grape 2 Hosts

30 Grape Version 2s were deployed prior to the April 8, 2024 total solar eclipse over North America.  The host stations are shown on this map.



The Grape Version 2 was designed by John Gibbons, N8OBJ, Lab Director of the Sears Undergraduate Electrical Design Lab, Case Western Reserve University, Department of Electrical Engineering.  Software applications were written by Bill Blackwell, AB1XB and Cuong Nguyen, KC3UAX.  The remote magnetometer board was designed, built and provided to host stations by David Witten, KD0EAG. Their efforts are being supported by a number of institutions and foundations:

Supporting Institutions