September 21, 2016

Technical Details

Frequency Bands

Wireless technologies for consumer electronics such as Wi-Fi and Bluetooth are usually carried out onto unlicensed ISM bands:

  • 902 to 928 MHz
  • 2.400 to 2.4835 GHz
  • 5.725 to 5.875 GHz

The advantage of TWevo is that the RF front end can be configured according to the specific requirements of your application. Since our solution is implemented using Software Configurable Radio we can easily set the central frequency and bandwidth.

Transmit Power & Distance

The regulation for ISM bands is as follows:

  • Maximum transmitter output power fed into the antenna is 30 dBm (1 watt).
  • Maximum Effective Isotropic Radiated Power (EIRP) is 36 dBm (4 watt).

For point-to-point links the regulation in US allows 48 dBm or 16W EIRP, whereas the maximum EIRP in EU is 100 mW (20 dBm). The transmission parameters in our system can be configured for a particular applications operating in a specific band for point-to-point links.

With an LNA having a noise figure below 1dB, the sensitivity of our RX is

QPSK modulation
Noise margin = 3 dB
SNR = 12 dB
Noise PSD (50 Ohm, room temperature) = -174 dBm/Hz
N @ 100 MHz = -94dBm
N @ 20 MHz  = -101dBm

Sensitivity = N + SNR + Noise margin + noise figure
Sensitivity @ 100MHz = -94 dBm + 12 dB + 3 dB + 1 dB = -78 dBm
Sensitivity @ 20MHz = -101 dBm + 12 dB + 3 dB + 1 dB = -85 dBm

Consider the following example for communication with a drone:

If we decide to operate in the 2.4 GHz ISM band, with the lowest modulation (QPSK, lowest speed) and two bandwidths: 100 MHz (TWevo max) and 20 MHz (WiFi/802.11g max). Assume that a UAV is flying high enough (few hundred yards) and omnidirectional antennas are used at both ends of the radio link (worst case). The maximum transmit power is set to 30 dBm.

The maximum distance that we expect per bandwidth is  2.5 km @ 100 MHz  and  about 5.5 km @ 20 MHz.