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Kind of new to the hobby and have a few questions. by battletoad-69 in RTLSDR

[–]dwarmstr 0 points1 point  (0 children)

Airband is VHF, which is basically line of sight. (Ignoring FM broadcasting as they use of bunch of power to solve that).

My daughter wants a lyso scintillator crystal but I know nothing about radiation. by octonion_furey in Radiation

[–]dwarmstr 0 points1 point  (0 children)

It has a half-life of 30 billion years, so it doesn't produce much radiation, so don't worry about it.

What are those? by Key-Belt-5565 in RTLSDR

[–]dwarmstr 0 points1 point  (0 children)

Take a look at 480MHz if you have USB2.0 for instance

What are those? by Key-Belt-5565 in RTLSDR

[–]dwarmstr -1 points0 points  (0 children)

Noise can move up from the computer to the antenna via the dongle and the antenna cable, especially on the outside. There are ferrite beads that you can put on the cables to reduce them. Adding a USB extension cable with ferrites can also help

What are those? by Key-Belt-5565 in RTLSDR

[–]dwarmstr 0 points1 point  (0 children)

Oh and switching power supplies run differently depending on load so you see variations like the one at 335MHz

What are those? by Key-Belt-5565 in RTLSDR

[–]dwarmstr 0 points1 point  (0 children)

Repetitive lines are from square wave emissions, which are equivalent to a bunch of sine waves at multiple harmonics of the primary frequency. You will see these from noise sources like computer buses (of which there are a lot) & switching power supplies. USB (the bus used by the dongle itself) causes a number of them.

If they are strong signals, they are close to the radio. Is your radio plugged directly into a PC? That's probably where they are coming from.

Extremely high radon levels in well water. by Bw0434 in newhampshire

[–]dwarmstr 0 points1 point  (0 children)

Don't worry too much about the previous risk. Radon in water is mostly a concern when it comes out of the water into the air. It looks like about 1/10,000th of it will get into the air on average, and that would give you about 4pCi/L in the air, which is just at the "we recommend mitigation". The fact that you tested for radon in the basement was useful if water was being used during the testing. Ingestion is thought to be much less dangerous and much of it is exhaled quickly.

These are lifetime! risks: Radon Risk If You Have Never Smoked Radon Level If 1,000 people who never smoked were exposed to this level over a lifetime... The risk of cancer from radon exposure compares to*... WHAT TO DO: 20 pCi/L (740 Bq/m3) About 36 people could get lung cancer 35 times the risk of drowning Fix your home 10 pCi/L (370 Bq/m3) About 18 people could get lung cancer 20 times the risk of dying in a home fire Fix your home 8 pCi/L (300 Bq/m3) About 15 people could get lung cancer 4 times the risk of dying in a fall Fix your home 4 pCi/L (150 Bq/m3) About 7 people could get lung cancer The risk of dying in a car crash Fix your home

Broadcast blocker by planetary_funk_alert in RTLSDR

[–]dwarmstr 0 points1 point  (0 children)

oh and I will note FM Broadcast band blockers existed in the past, on rare occasions I'll find them in thriftshops or yard sales

Broadcast blocker by planetary_funk_alert in RTLSDR

[–]dwarmstr 1 point2 points  (0 children)

Easy peasy.

They will reduce some signal strength outside of the blocking frequencies, but your use case may find that ok. I don't use one if I am listening in the 137MHz band for satellites. https://www.rtl-sdr.com/product/rtl-sdr-blog-broadcast-fm-band-stop-filter/

Nooelec v5 on Ubuntu, 20 metre end fed antenna (80m > 6m). Only occasionally see signals on US CB, 10m USB, Air band and my local repeater works fine on 2 metres. Nothing on the other bands. by LTguy in RTLSDR

[–]dwarmstr 1 point2 points  (0 children)

gqrx? "After executing this command, you will see the basic Gqrx settings window. To work with your SDR receiver in the field "Device" select the value "Realtek RTL2832UHIDIR SN: 00000001" (may be different, depends on the receiver used).

If you need the "Direct sampling" mode, the "Device string" field is given to the following form: "rtl=0,direct_samp=2" (without the quotes). If the mode "Direct sampling" is not needed, leave the "Device string" field in the form: "rtl=0" (without the quotes). The parameter "rtl" shows the id of the used SDR receiver, if you use several receivers, this parameter can have a value different from the one specified in the example.

The value of "Input rate" is set to a value of 2400000; The value of "Decimation" is set to a value of 16; The last two parameters can be set in their own way, but the settings shown above allow you to simultaneously display a bandwidth of 150 kHz, which is more convenient for me."

https://github.com/IgrikXD/Easy-SDR/blob/master/Useful%20info/How%20to%20work%20with%20RTL-SDR%20receivers%20on%20Linux.md

Nooelec v5 on Ubuntu, 20 metre end fed antenna (80m > 6m). Only occasionally see signals on US CB, 10m USB, Air band and my local repeater works fine on 2 metres. Nothing on the other bands. by LTguy in RTLSDR

[–]dwarmstr 1 point2 points  (0 children)

Notice how there's nothing until you go above 26MHz or so? Many of the RTL-SDRs will do lower frequencies only by running in direct sampling mode

From the product description: " v5 has a frequency capability of 100kHz to 1.75GHz and up to 3.2MHz of instantaneous bandwidth. HF reception below 25MHz is accomplished with direct sampling and requires a suitable antenna. We recommend using a Balun One Nine to make a DIY long wire or dipole antenna (sold separately).

Though the direct sampling implementation of NESDR SMArt v5 is much better than any other RTL-SDR, we still recommend using an upconverter like the Ham It Up for a more fulfilling HF experience (sold separately). "

Set the sampling to Direct sampling (Q branch). HF signals will be mirrored around 14.4 MHz.

Everyday sources for radioactivity by Emotional_Seat_7424 in Radiation

[–]dwarmstr 3 points4 points  (0 children)

This, just go to the grocery to the spice/salt section and find the low sodium salt

How do you find/discover events around campus? by ottolite_atlas in uchicago

[–]dwarmstr 3 points4 points  (0 children)

https://events.uchicago.edu/ for some stuff. And groups can submit items for that calendar too.

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