RF Link Budget Calculation Or RF Receive Power calculation

RF Link Budget Calculation is the calculation of the receive RF power at the Receiver based on the transmitter RF power, RF cable losses, Tx Antenna Gain, Free Space Loss(FSL) Rx Cable Loss, Rx Antenna Gain

So the equation is

Receive Power (dBm)  = Tx Power (dBm)  - RF Cable Loss(dB) + Tx Antenna Gain(dB)  - Free Space Loss(dB) - Rx Cable Loss(dB) + Rx Antenna Gain (dB)

The calculation of the Free Space Loss

With Kilo Meter as the unit for distance
Free Space Loss(FSL) dB = 32.44 + ( 20 * Log(Frequency in MHz) ) + ( 20 * Log(Distance_In_KM) )

With Miles as the unit for distance
Free Space Loss(FSL) dB = 36.6 + ( 20 * Log(Frequency_In_MHz) ) + ( 20 * Log(Distance_In_Miles) )

Error Vector Magnitude (EVM) db to percentage calculation

For converting  Error Vector Magnitude (EVM) from db to %(percentage), we can use the below formula

EVM in % = 100 * (10^(EVM in dB/20))


Example:

EVM = -18 dB

EVM % = [100 * 10^(-18/20)] %
EVM % = [100 * 0.125892] %
EVM % = 12.589 %

how to list hidden folders in windows command line

For showing all the folders which are hidden we can use the dir command in the windows command line

 dir /a:dh /s d:\


 the above command will show all the hidden directories in the drive D:\, it will also show the sub directories. Change the last string to the specified drive or folder where you want to search

for writing these output to a file , use the below command

dir /a:dh /s d:\ > FilesName.txt

Hope this helps t

R cannot be resolved android error

when i was doing the android app, the below error was coming after developing for some time when i opened the eclipse.

R cannot be resolved 

even though the same code was working  previously. after googling found that if we clean the project form the menu

 select "Project" -> "Clean..." 

Hope this helps for others. 

In Microsoft Word 2010 Leveled Numbering list turns to black box

I searched some forums and got the fix, please follow the below points

1. Put your cursor on the heading just right of the black box
2. Use the left arrow key on your keyboard to move left until the black box turns grey
3. Use the keyboard combination ctrl+shift+s, the dialog "Apply Styles" should appear
4. In this box, click "reapply"

taking screenshot in android 4.0 and above

 Taking a Screenshot in Android 4.x

To take a screenshot on your android device from version 4 and above , press the Volume Down and Power keys at the same time.

The screenshot will be saved on the gallery->Screenshots folder, \

you can select it and share through mail/bluetooth etc. and other sharing methods available, same as sharing a normal photos.

android: sending SMS programmatically

In android app, if you want to send SMS using the carrier network, you can use the below function. Pass the destination mobile number and the SMS string within specified characters.


public boolean sendSMS(String dstAddress, String smsMessage)
    {
   
    try {
SmsManager smsManager = SmsManager.getDefault();
smsManager.sendTextMessage(dstAddress, null, smsMessage, null, null);
Toast.makeText(getApplicationContext(), "SMS Sent!",
Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(getApplicationContext(),
"SMS failed, please try again later!",
Toast.LENGTH_LONG).show();
e.printStackTrace();
return false;
}
return true;
    }