Solar Radiation AM - Danilo's Question

In summary, the sun radiates in the radio range and short-term variations in light intensity emitted by the sun can get past the current block used to filter out DC current. Atmospheric effects are more likely to cause fluctuations in light intensity.
  • #1
danroa
3
0
First of all, this is my first post here. So, hello everyone! :smile:

I have a question about the solar radiation and that I don't seem to be able to find an answer for on the net.

I'm building an IR transceiver for data transmission that should be able to withstand some amount of direct sunlight on the photodiode. I already made some prototypes, and filtering out the DC current generated by direct sunlight it's an easy task. But now I'm particularly worried if the solar radiation in space (with no atmosphere filtering) may have some "amplitude modulation" around the megahertz range (let's say, from 10 kHz to 10 MHz in both visible and IR spectrums) that could get thru the DC block.

Every study I could find on the net is about longer term variations of the solar radiation (from hours to centuries) and I can't find anything on shorter term ones. Maybe it's just because there is no variation on shorter terms... But, you know... :wink:

Anyway, if anyone here could shed some light on the subject, I would be grateful.

Danilo
 
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  • #2
Sun radiates in radio range

I'm in solar astronomy but not an expert in radio. The sun radiates in the range you
are in interested in from the 'quiet sun' and from 'active regions'. there are variations as
these regions evolve and the sun rotates. Also, eruptions such as flares and coronal mass ejections cause increases in radio emission over timescales of minutes to hours. I believe there are websites showing plots of emission versus time measured by satellites. Also, there are several ground based radio observatories that provide such data. google:
solar radio observatory, or: in-situ solar radio emission
 
  • #3
heliotrope said:
Also, there are several ground based radio observatories that provide such data. google:
solar radio observatory, or: in-situ solar radio emission

Yeah. I know the sun radiates in the radio range. But I'm not interested in electromagnetic radiation in the megahertz range. I'm interested in "amplitude modulation" of the light emitted by the sun in the megahertz range. I mean, quick variations in the IR (or visible) light intensity that would get past the DC current block I used on the photodiode.

Danilo
 
  • #4
AM should be quite small

sorry, i didnt read that carefully enough. there is not a lot published on this topic, probably because the modulations in IR intensity in the megahertz range are very small. I would guess the relative amplitude is less than 1/1,000,000. the flucutations caused by passage through Earth's atmosphere are much larger.
 
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  • #5
I would worry more about atmospheric effects. The timescale for atmopsheric seeing (star twinkling) is upto a few 100Hz.
 
  • #6
Sorry for the late reply, but I've been quite busy.

heliotrope said:
I would guess the relative amplitude is less than 1/1,000,000. the flucutations caused by passage through Earth's atmosphere are much larger.

Exactly what I guessed at first. Just wanted someone else's opinion too.

mgb_phys said:
I would worry more about atmospheric effects. The timescale for atmopsheric seeing (star twinkling) is upto a few 100Hz.

Interesting. I will dig into that. However, luckily for us, atmosphere is nothing to be concerned about. :smile:

Thanks everyone.
Danilo
 

1. What is solar radiation AM?

Solar radiation AM, or solar radiation in the air mass spectrum, is the amount of energy from the sun that reaches the Earth's surface at a specific location and time. It takes into account the filtering effects of the Earth's atmosphere, which varies depending on the angle of the sun and the thickness of the atmosphere the sunlight must pass through.

2. How is solar radiation AM measured?

Solar radiation AM is measured using specialized instruments such as pyranometers or solarimeters. These instruments measure the amount of solar energy that reaches a specific surface area over a given time period. The resulting measurement is usually in watts per square meter (W/m2).

3. What factors affect solar radiation AM?

The amount of solar radiation AM received at a specific location is affected by several factors, including the time of day, season, weather conditions, and location on the Earth's surface. The angle of the sun's rays and the thickness of the atmosphere also play a role in determining the amount of solar radiation AM at a particular location.

4. Why is solar radiation AM important?

Solar radiation AM is important for several reasons. It is a crucial source of energy for many living organisms and plays a significant role in sustaining life on Earth. It also provides the energy needed for photosynthesis in plants and is a vital component of the Earth's climate and weather patterns. Solar radiation AM is also used to generate electricity through solar panels and is an important factor in renewable energy production.

5. How does solar radiation AM impact the Earth's climate?

The amount of solar radiation AM received by the Earth's surface affects the planet's overall climate. Changes in solar radiation AM can lead to variations in temperature, which can have a significant impact on weather patterns, ocean currents, and the Earth's overall climate. Understanding solar radiation AM is essential for predicting and mitigating the effects of climate change.

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