How to calculate the Theshold degradation?

[DAVID]

Hi everybody!
I have an interference wich comes from 34? to the right of my microwave link. This interference is -80.48 dB isotropic value. My antenna gain is 43.6, The antenna discrimination for 34? is -57 dB. I also have a lineloss of 3.79 dB in waveguide. The radio's threshold level is -69 dB And I have the information of T/I=23 dB for this radio.
The question is: How to calculate the threshold degradation of my radio. Once I have this value, I'm going to put it on the interference dialog box under operations under worksheet module of Pathloss in order to know how my link will work.

Could anybody help me?

Thanks.

[Linas Spraunius]

In order to calculate TD of your system you need to have receiver noice level.

[DAVID]

Linas Spraunius

You mean Nrx. In the Pathloss Manual there is a formula. This is Nrx = Trx -T_Ic + 5.868
And the formula for Td is:
Td = Nrx -10log (10^(Nrx/10) + 10^(Ifl/10))
Where:
Trx = -69 dB
Ifl = Isotropic interference value + antenna discrimination for 34? + antenna gain + wiveguide loss
This is:
Ifl = -80.47 - 57 + 43.6 - 3.79 = -97.66 dB in this case.
But I have a doubt: Is T_Ic the same as T/I ?
If this value is the same, now I can obtain the Td. Please tell me if I'm right or I'm wrong.

By the way, thanks for answering my question.

[Linas Spraunius]

The general formula for calculation of TD:
TD=10log(1+10^((I-N)/10))
I- Interference signal
N- Receiver noice level
How to calculate TD with Pathloss I don't know. I'm new to Pathloss. I tave it only 4 days and it's not so easy to understand it :(

[David]

Thanks for help me. I must say this problem seems to be solved with the biggest antenna in one side of the link, that means maximun gain.