Radio Spectrogram/Spectrograph Archives

Longwire antenna, earliest mostly full-day data I could find.

The strong signals at the left are on the longwire, the rest is on the 15-17-20 meter fan dipole. I think the vertical bands like in the center are intermod. Black bands are times without data for various reasons.

First fan dipole pic. Left part is using a cable TV preamp that doesn't work below 45 MHz. It's only rated down to 50.

This the palette file used for all these plots. I extracted it from one of Learmonth Observatory's GIF files. Signal intensity values from typically 600 to 7000 are autoscaled into a range of 50-255 and then a color is chosen for that pixel based on the rgb values for that position in the palette. What I don't like about it is that colors for intensities at about 0x4F look almost like those for 0xEF. Those white horizontal lines in the spectra that are 6 meter repeaters are at an intensity of 6000-7000, but most of everything else is at 700 - 1000. Details in the ranges beween that should plot as oranges, greens, purple are squashed out by the autoscaling process. I need to maybe do some histograms of intensities and decide if I really want to autoscale them. In the beginning it served a purpose but now I think it's obscuring data.

Internal preamp(s) in the IC-7000 turned on.

This is on the fan dipole 200 ft from the house. Notice the almost-regular horizontal bands which I thought were dipole resonances. Also the lack of 40-45 MHz trash.

This is on the T2FD in the raspberry patch (200 ft from the house). The vertical streaks toward the right are ignition noise from a line trimmer at least 500 ft away. It's back on the next one too (weekend afternoons). Everything's autoscaled including the intensity so strong noises like this affect the colors used for everything else.

I put a shorting plug on the fan dipole which is about 6 feet away, but I'm still getting these horizontal bands.

The vertical streak about halfway between noon and midnight here almost looks like what I'm hoping to see.

This could be intermod in the upper left corner or it could be what I'm hoping to see. Probably intermod: at 2 AM UTC neither the sun or Jupiter were up.

About the only interesting thing here is seeing how lightning looks with this setup. It sort of looks like rain in the picture. There was lightning somewhere in the vicinity for almost 12 hours, I'm not sure how far away I can detect it. It's fall hurricane season, happens every year.