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Radio sensitivity

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alphacat

New Member
Hey.

My MCU transmits and receives information wirelessly.
Currently, its sensistivity is configured to -91.
Its possible to upgrade it to -92 (it just will take some time to unpack the units, burn the code and pack it up again).

So, until i'll have this test, i wanted to ask you if theoretically there should be a difference in the reception range due to this upgrade and in the "qualitiy" of the network (meaning experiencing less momentary disconnections due to loss of packets).

For example, when I increased the TX output power by 1dBm (from -0.4dBm to 0.6dBm) i noticed the improvement.

Thank you.
 
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RadioRon

Well-Known Member
Hey.

My MCU transmits and receives information wirelessly.
Currently, its sensistivity is configured to -91.
Its possible to upgrade it to -92 (it just will take some time to unpack the units, burn the code and pack it up again).

So, until i'll have this test, i wanted to ask you if theoretically there should be a difference in the reception range due to this upgrade and in the "qualitiy" of the network (meaning experiencing less momentary disconnections due to loss of packets).

For example, when I increased the TX output power by 1dBm (from -0.4dBm to 0.6dBm) i noticed the improvement.

Thank you.

Yes, in theory an improvement of 1 dB should result in a change of as much as 10% better range, at least for unobstructed line-of-sight links. But such a change is very hard to notice in practical situations because multipath propagation (reflections) creates a very complex pattern of high and low signal levels at the receiving location, and the variation due to reflections can be higher than +/- 10 dB, so a 1 dB improvement may be swamped by this additional variation that is entirely dependent on location and the movement of objects near the radios and in the path.

The throughput (or error rate) improvement that you might get with 1 dB more signal depends on the kind of signalling/modulation you are using. For example, in 802.11a systems, 1 dB can make a significant difference.
 
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alphacat

New Member
Yes, in theory an improvement of 1 dB should result in a change of as much as 10% better range, at least for unobstructed line-of-sight links. But such a change is very hard to notice in practical situations because multipath propagation (reflections) creates a very complex pattern of high and low signal levels at the receiving location, and the variation due to reflections can be higher than +/- 10 dB, so a 1 dB improvement may be swamped by this additional variation that is entirely dependent on location and the movement of objects near the radios and in the path.

The throughput (or error rate) improvement that you might get with 1 dB more signal depends on the kind of signalling/modulation you are using. For example, in 802.11a systems, 1 dB can make a significant difference.

Hey Ron,
Thanks alot for your answer.

What do you think about upgrading the sensitivity of the RX from -91 to -92?
Should there be a noticeable difference (By theory)?
 
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RadioRon

Well-Known Member
Hey Ron,
Thanks alot for your answer.

What do you think about upgrading the sensitivity of the RX from -91 to -92?
Should there be a noticeable difference (By theory)?

Well, I thought I already answered your last question, but anyway, yes if it costs you no money and little effort and not much additional power consumption and nothing else that could be bad, then sure why not upgrade? But if it is a bunch of extra work, I wouldn't bother.
 

alphacat

New Member
Hey,
Thank you very much :)

I'm sorry, I just found out that sensitivity is expressed by dB units.
(I thought at first that you were talking about the TX output power).

I hope I could see that same improvment that I observed when increasing the output power by 1 dBm.
 

tytower

Banned
Dont want to step on RadioRon's toes here and I agree with all he says but in addition I have always prefered to look at radio waves like light when talking about high Megahertz as in UHF . Light reflect off a mirror and so do these high frequency waves reflect off any metal they hit . So the waves are coming from various other directions in addition to the main beam and with varying and unpredictable time delays.

Good point is the road signs bounce radio waves everywhere so where speed guns are positioned greatly affects their accuracy.
 
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RadioRon

Well-Known Member
Hey,
Thank you very much :)

I'm sorry, I just found out that sensitivity is expressed by dB units.
(I thought at first that you were talking about the TX output power).

I hope I could see that same improvment that I observed when increasing the output power by 1 dBm.

Oh, I see, that explains why you answered that way. No problem.

As for multipath, this is the word we use to talk about the way that radio waves go from transmitting antenna to receiving antenna when there happens to be a lot of RF reflectors around. The radio waves can get to the receiving antenna by travelling straight to it, but they can also get there by bouncing off things nearby, like the sides of buildings, trucks and other things. So, the radio waves can get to the receiving antenna via "multiple paths", hence the word multipath. Unfortunately, each path is a slightly different distance, and these differences become large with respect to the wavelength of the RF at UHF and microwave frequencies. So, when all the different pathway's RF signals arrive at the receiving antenna, they are out of phase with each other and so you get a mix of constructive and destructive combination. So the amplitude of your signal can be higher or lower than if you were receiving only the direct path alone. The amplitude also then varies with the exact position of the receiving antenna, and it also varies if any of the reflectors are moving (which they often are). So amplitude variation due to multipath is a fact of life at higher frequencies.
 

alphacat

New Member
Hey,
I wanted please to ask about one more thing please.

In the low level code, I have the option to set
MAC_RADIO_RECEIVER_SATURATION_DBM (by default its set to 10 dBm).

Do you know please what does it mean, Radio Receiver Saturation?

Thanks.
 
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RadioRon

Well-Known Member
Hey,
I wanted please to ask about one more thing please.

In the low level code, I have the option to set
MAC_RADIO_RECEIVER_SATURATION_DBM (by default its set to 10 dBm).

Do you know please what does it mean, Radio Receiver Saturation?

Thanks.

I can only give a general answer as I'm not familiar with the receiver you are using. Saturation in general means completely full and can't accept any more. In the case of a receiver, it usually means the maximum level that the receiver can receive without excessive distortion or errors occurring.
 
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