Test: Field
Before conducting a full field test as below, it is wise to test the system in parts and in the lab first to verify correct operation.
Brainstorm: ideal to test through actual ionosphere for the final testing. Say one unit at BU and a second unit at Haystack, UNH or WPI. Idea is to be far enough away > 50 km so that communication is via skywave and not groundwave. We can verify via BU Amateur Radio Club high power transmitter that groundwave isn't occurring (using existing high power transmitter on other end too) before deploying.
Low sunspot number drives critical frequency lower, so we may be only able to run tests during daylight hours in the 7 MHz band.
Ham radio operators may want to test (this is designed for hams to use after all).
| test site | great-circle distance from BU [km] | transit options (from BU) |
|---|---|---|
| UNH | 85 | car or Amtrak Downeaster ~ 1.5 hour |
| Haystack | 40 | car ~ 1 hour |
| WPI | 60 | car ~ 1 hour |
| Dartmouth | 175 | car ~ 2.5 hours |
From the earliest days of radio, diurnal and decadal variability of the ionosphere has been prominently apparent. For the NVIS CONOPS typical to this system, frequencies between 2-10 MHz are best. The best frequency typically shifts up by down and down at night, and is also highly dependent on solar activity. During massive solar storms or nuclear war, HF radio blackouts occur.
The representative plot for Oct 2016 is using the default parameters of VOACAP online, which are not necessarily suitable for our project. They are however representative of the diurnal change in optimal NVIS frequency. The site coordinates are representative of BU and UNH.
