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# EIRP & Rx Level

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• #58717 Reply
David
Guest

Hey,

Is there any one to tell me the formula to calculate Rx level that gets displayed in my tems when i know the eirp of that location.

#58718 Reply
Bijoy
Guest

Rx Level (dBm) =
Tx Power − Cable/Connector Loss + Antenna Gain − FSPL + Antenna Gain − Cable/Connector Loss

#58719 Reply
Pix
Guest

or more simply, since you know your EIRP:

RxLev = EIRP – path loss

path loss depends on distance, obstacles, radio propagation, frequency, fading, dust in the air, temperature, etc etc etc etc etc.
🙂

#58720 Reply
david
Guest

hey,

taking a micro cabinet as an example with a TX Power of 33dBm, and connecting an antenna of 2 dbi directly, wat will be the rx level i get for this then? EIRP for this will be 33-0+2=35dbm.

Pix,

As u said, if RX level=EIRP-pathloss, and as i dont have any pathloss here, my rxlevel should be 35 u mean?

but the rx level we receive in tems pocket is in -ve. there lies the confusion.

Bijoy,
u have added antenna gain 2 times. how is it? and wat does FSPL mean?

Now have a look at this formula. Its from a practical tool. But i dont understand the values used here.

RX Level=EIRP-(32.4+20*LOG10(0.9)+10*3*LOG(D)) where D is Distance in m.

pls clarify

#58721 Reply
Bijoy
Guest

Hi David
-ve occur because we measure it from the receiver end.

FSPL means free space loss
(FSPL + Rx Antenna Gain − Cable/Connector Loss)=Total Line loss.
EIRP= Tx Power − Cable/Connector Loss + Tx Antenna Gain.
So RX Lev =EIRP- Total Line loss.

As per your example
Rx lev=-EIRP(since we r on the receiver side)-Total Line loss.

hope u got it

#58722 Reply
Pix
Guest

Bijoy / David,

Ok, in Bijoy’s complete formula, that’s the Tx antenna gain on one side, and then the Rx antenna gain on the other side, from the receiving device.

David,

The formula you wrote is :
RxLev = EIRP – Path loss
with the path loss = 32.4 + 20.LOG(…) + etc.

there will always be path loss : how do you measure the RxLev ? With a measuring device ? How far is it from the Tx Antenna ?
If you measure the output from the antenna directly, being physically connected to the dipoles, then the RXLEV = EIRP.

Path loss : it is the loss due to waves “blowing” the energy all over space. The energy is not concentrated in one point anymore : it goes everywhere. Since you are measuring the remaining energy from one point only, the RxLev is way less than the initial EIRP.

#58723 Reply
David
Guest

Pix,

I measure using a normal TEMS Pocket. And the distance willbe approx. 0m. So, as u say in your second point i can say its almost connected physically. So RXlvl=EIRP. But i receive in -40 dBm level. Why is it so?

Help please

#58724 Reply
Pix
Guest

Hi david,

Why are you so close toan antenna ? You don’t want to have kids anymore ?

Regarding TEMS… the max rxlev that can be measured by this device is probably -40dBm. The range is just not enough.

#58725 Reply
David
Guest

Hey Pix,

U can name me workaholic?:) Its was jus a testing panel antenna of gain 7dBi. is that too dangerous? Let us be a bit biological.

#58726 Reply
Bijoy
Guest

Hi David
I gave got Rx lev as high as -7dBm with Net monitor for an IBS site.
what is the device you are using?

#58727 Reply
Pix
Guest

David, I hope you are a bit more than “a bit biological”. Please, pay attention to your sperm count 😉

7dBi on top of a macro BTS means that you are facing about 55dBm, which is around 200W of pure electromagnetic waves.

That is considered as dangerous, without any doubt.

Bijoy : TEMS pocket.
TEMS Investigator is limited to -40dBm (or about.), I assume TEMS poccket has the same limitation.

#58728 Reply
Bijoy
Guest

Hi Pix
Lets not asuume anymore
I’m saying what i’ve seen.
I’ve also seen RX lev as high as -15dBm in TEMS investigation.

I can mail u the snapshot

#58729 Reply
Pix
Guest

Bijoy,

He is using TEMS pocket, not T.I.

The limitations in Net Monitor, Tems investigation or Tems Pocket are probably different from each others and in my opinion, that’s where the cause of his problem is. I’m not doubting what you have seen at all.

(note: I clearly remember that TI 5 or 6 was limited to -40dBm (or perhaps -35dBm), but certainly the limitation is now gone with the newer releases. Or it’s just my memory that got fried by too much GSM exposure)

#58730 Reply
Bijoy
Guest

hi pix
I think u r right in case of TEMS pocket.

#58731 Reply
David
Guest

Guys,

I accept it. But my vendors fight with me saying as my RX Level is -40 range they could not give the stipulated EIRP. They dont accept the fact that TEMS Pocket is a miser in levelling. Funny world.

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