In the previous five posts, I looked at my receiving equipment used for GOES16, to see if I could re-purpose it for reception of the so called hydrogen line at 1420MHz/21cm (Ref.1/5). Over several weeks I tried and experimented with various times/configurations but was not able to receive the hydrogen line. Finally I took a wide-band power measurement and discovered that my downtown location was extremely hot from an RF perspective at -34dBm! I also located an OFDM type signal at 1440MHz which may have been causing intermodulation due to it’s high level and similarity to the comb I was seeing on my background.
I decided to move the equipment to a location far outside the urban environment. Figure 1 shows the test location 52Km north of Toronto in a farming valley, surrounded by hills. The background wide-band level did not even register on the power meter as shown in Figure 2. This proved an ideal location and I was able to clearly see the line. This has been the most challenging project I have done over the past 2 years!!
Dish Alignment & Signal Reception
Figure 3 shows the Stellarium view of the Milky Way from the test location. I first aimed the dish directly west away from the MW to calculate the background. Note the two spurious as shown in Figure 4 (the old enemy 1420.8 is back!). Figure 5 shows the receive signal minus the background which is stable and very flat. Then I moved the dish to the south east at almost vertical. The Hydrogen line is clearly seen in Figure 6. I followed the excellent procedure as outlined in Reference 6.
#1. – “RTL-SDR for Radio Astronomy – EM Interference”
#2. – “RTL-SDR for Radio Astronomy – Signal Capture1”
#3. – “Radio Astronomy LNA/BPF Testing with NanoVNA”
#4. – “RTL-SDR for Radio Astronomy – LNA/BPF Testing”
#5. – “RTL-SDR for Radio Astronomy – Planning
#6. – “Cheap and Easy Hydrogen Line Radio Astronomy with ….”