VHF communication - sensitivity check for receivers

[ashumtech]

I am working in an aircraft industry on vhf radio for aircrafts. I want to make sensitivity check of my recievers. The specifications of the transceiver says -97 dBm for SINAD not less than 10 dB. Kindly give me help to understand this.

 

[vedagarbhamsandeep]

Re: VHF communication basics

Transmitted power from your receiver which may include LNA / PA / etc = -97 dBm = 127W Approx

SINAD is same as Signal to Noise Ratio - >10dB

Generally, the sensitivity of any device is the minimum i/p signal (power in W or dBm) required to drive your receiver keeping the SNR and input power on mind. There should be few formulas which i cannot recollect. Maybe you can check on google or anyone else could be of better help.

 

[volker_muehlhaus]

Re: VHF communication basics

Transmitted power from your receiver

??

-97 dBm = 127W Approx

No.

-97 dBm = 0.2pW
-97 dBm = 10dBµV @ 50 Ohm

Online calculator: **broken link removed**

 

[vedagarbhamsandeep]

Re: VHF communication basics

ya, its 0.2pW. i did a quick pen paper calc and dont know where i went wrong !

But thats very low power ..

 

[vfone]

Re: VHF communication basics

From my knowledge in aircraft industry minimum SINAD requirement is 12dB (and not 10dB).

Anyway, here is a nice paper from Aeroflex that explain SINAD measurements:
**broken link removed**

 

[BigBoss]

Re: VHF communication basics

You would like to measure the sensitivity of the radio ???
Connect a signal generator to input, adjust a FM modulation within specification say 1kHz of modulation frequency,5kHz FM deviation or more.(NBFM)
Check the SINAD at the audio output by decreasing RF output level of the generator and when you see SINAD=10-12dB, stop it and read the RF input level.
Consider cable losses and connecor losses and make them calibrated well.

 

[davenn]

Re: VHF communication basics

ya, its 0.2pW. i did a quick pen paper calc and dont know where i went wrong !

But thats very low power ..

Receivers DONT transmit power they receive .... thats where you went wrong

the -97 dBm for SINAD not less than 10 dB. referred to by the OP is the receiver sensitivity to an incoming signal

Dave