Introduction
Recently I was in Costa Rica (Ref.1) and I used WWV to set my watch for UTC time to accurately read my sextant. We tend to take time for granted now with the Internet & GPS, but time stations like WWV still provide an essential service. WWV (Ref.2) can also be used to study propagation. In previous posts I used the Canadian time Station CHU (Ref.3).
WWV Station Parameters
| Frequency | Power |
| 2.5MHz | 2.5KW |
| 5.0MHz | 10KW |
| 10.0MHz | 10KW |
| 15.0MHz | 10KW |
| 20.0MHz | 2.5KW |
| 25.0MHz (Experimental) | 2.5KW |
| Transmission: AM_DSB , 50% Tones, 100% Secs, 75% Voice | |
| Antenna: 1/2 Wave Vertical Omnidirectional | |
| Latitude = 40.68degN Longitude = 105.04degW |
Figure 1 lists the WWV station parameters and frequencies used. Transmit power is 10KW on all bands, except 2.5/20/25MHz where the power is 2.5KW. Antennas are 1/2 wave verticals, with the 25MHz antenna as a 1/2 wave vertical dipole (Ref.2). Figure 2 shows the path between WWV and my home QTH on Google Earth.
RTL-SDR Reception
Figure 3 shows WWV reception at 2.5/5.0/10.0/15.0/20.0MHz. The carrier shown at 2.5MHz is not WWV but probably a harmonic/intermod of the RTL. There is no signal visible at 5.0/10.0MHz. A small carrier signal was seen at 15.0MHz and a clear signal at 20.0MHz. Figure 4 shows reception at 20MHz with the special propagation signal sent at 8min past each hour.
VOACAP
VOACAP is a powerful HF propagation program originally developed for the Voice of America (Ref.4). It can be used as stand alone or with an interactive web interface. Figure 5 shows the web interface for propagation analysis between WWV and my home QTH. Figure 6 is the resultant propagation wheel and Figure 7 is the Propagation chart.
| Band Meters/MHz | Prop Reliability % |
| 10m/30MHz | 0 |
| 12m/25MHz | 10 |
| 15m/20MHz | 60% |
| 17m/17.6MHz | 80% |
| 20m/15MHz | 70% |
| 30m/10MHz | 60% |
| 40m/7.5MHz | 30% |
| 60m/5.0MHz | 0% |
| 80m/3.75MHz | 0% |
Figure 8 shows the propagation reliability figures taken from the Prop Wheel in Figure 6. The RTL-SDR receive levels indicate a good signal at 20MHz, very weak signal at 15MHz and no signal anywhere eles. This corresponds to the propagation wheel results.
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References
#1. – “RTL-SDR for UTC Time in The Tropical Rainforest”
https://jeremyclark.ca/wp/nav/rtl-sdr-for-utc-time-in-the-tropical-rainforest/
#2. – “WWV Time Signals”,
https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwv
#3. – “VOACAP – CHU to VE3PKC”
https://jeremyclark.ca/wp/telecom/voacap-chu-to-ve3pkc-2/
#4. – “VOACAP”,
https://www.voacap.com/
