SDR-IQ for HF WWV Propagation

Introduction

Fig.1 HF Propagation Testing

In previous videos I looked at HF propagation using WWV, CHU and NCDXF/IARU beacons (Refs.1/4). Recently the Canadian CHU time station was taken off the air. In this post I will look at receiving WWV using the SDR-IQ receiver and a 10m long wire as shown in Figure 1. WWV station frequencies are 2.5/5/10/15/20/25MHz. Transmit power is 10KW on all bands, except 2.5/20/25MHz where the power is 2.5KW. Antennas are 1/2 wave verticals mounted on a 1/2wave vertical towers. Transmission: AM_DSB , 50% Tones, 100% Secs, 75% Voice. Latitude = 40.68degN & Longitude = 105.04degW (Ref.5).

SDR-IQ Reception

Fig.2 VOACAP Circuit Reliability WWV to Toronto Canada Nov3rd_2026 11:17EDT/16:17UTC
Fig.3 Off Air Rx Signal 5MHz & 25MHz 1030EDT/1530UTC
Fig.4 Off Air Rx Signal 10MHz & 15MHz 1030EDT/1530UTC
Fig.5 Off Air Rx Signal 20MHz 1030EDT/1530UTC
FrequencyTx PowerRx/Noise Level dBVOACAP
1430UTC
5.0MHz10KWnoise/-1300%
10.0MHz10KW-85/-12060%
15.0MHz10KW-75/-10580%
20.0MHz2.5KW-90/-11085%
25.0MHz (Experimental)2.5KWnoise/-12540%
Fig.6 WWV Station Parameters & Rx Levels

Figure 2 shows the VOACAP propagation wheel for transmission between WWV and Toronto Canada for Nov3rd_2026 at 11:17EDT/16:17UTC. Figures 3/4/5 show the received signal levels as captured on Spectravue. No signals were received on 5MHz & 25MHz, good signals on 15MHz & 20MHz and a weak signal on 10MHz. These levels correspond with the reliability figures given by VOACAP. You can see/hear the signals on the YouTube video.

Solar Cycle 25

Fig.7 NASA Plot of Solar Cycle 25

From Figure 7 you can see that we have passed the maximum of Solar Cycle 25 which peaked in 2025 (Ref.6).

Fig.8 YouTube Video SDR-IQ for HF WWV Propagation
HF Amateur Radio Blog Topics

HF Radio Telecommunications Learn by Simulation

Please send your comments, questions and suggestions to:
contact:

YouTube Channel
YouTube Channel

References

#1. – “RTL-SDR for HF WWV Propagation”
https://jeremyclark.ca/wp/telecom/rtl-sdr-for-hf-wwv-propagation/

#2. – “RTL-SDR for HF Beacons Propagation Prediction”
https://jeremyclark.ca/wp/telecom/rtl-sdr-for-hf-beacons-propagation-prediction/

#3. – “VOACAP – CHU to VE3PKC”
https://jeremyclark.ca/wp/telecom/voacap-chu-to-ve3pkc-2/

#4. – “VOACAP”,
https://www.voacap.com/

#5. – “Radio Station WWV”,
https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwv

#6. – “NASA Solar Cycle Progression”
https://www.nasa.gov/solar-cycle-progression-and-forecast/

By Jeremy Clark

Jeremy Clark is a Senior Telecommunications Engineer and Advanced Amateur Radio Operator VE3PKC. He is the author of E-Books on Telecommunications, Navigation & Electronics.