Typical TX distance A 0dbm and at 20dbm (2.4GHz)
My application is a bidirectional data stream that needs 'full quieting' about 97% of the time.
I'm seeing about 10-20 feet, line of sight using quarter wave mono's on both sides with 0dbm. I'm considering throwing in an PA but would like to know if 20dbm will work where ever I go around my house.
At this frequency assuming RX and TX antennas with 0dB gain and a level of -70dBm at RX antenna connector (for a good reception), the line of sight in free air between antennas would be 40m, when you transmit 0dBm.
At 20dBm TX power, the line of sight in free air theortically will be 300m.
In reality for both cases the distance would be less, due to absorptions, multipath, etc.
20dBm should be ok for a link all around your house.
Free Space Path Loss [dB] = 27.6-20*LOG(Freq_MHz)-20*LOG(Distance_meters)
Thanks. the 0dbm seems to also be line of sight... do you think with the 20dbm output will be able to walk between it, through walls, etc?
Dear,
Usually there isn't any problem if your receiver sensitivity is enough.
I use a 20dbm USB-Bluetooth (I think bluetooth V2) marked as 100m without any
problem.My phone bluetooth is 0dbm (V1) and it's works with my headset,in line of
sight without walls about 10~13m and with walls about 5~7m.
Good Luck.
20dBm should be enough power to go through walls of your house.
Hi mikal
If you do not have the ideal 'line of sight' with no reflections, you can never guarantee that your link will not be interrupted. The most problems are caused by reflections. You could be at a very short distance (for example 10m, transmitter in line of sight) but the receiver also receives a multipath signal which travels lambda/2 longer. If both signals would have the same strength you will have a null in the reception power, so your link is broken!
To overcome this problem you can use antenna diversity or a very broadband signal transmition (e.g. spread-spectrum)
Regards