Users Manual

6
 Click ‘disconnect from device’ icon.
 Now the programming cable can be removed from the module and the module is ready for
testing.
Firmware bin file details:
The firmware files that will enable transmissions in fixed frequencies are named as follows:
 VM_WTRGAS_FCC_LOW (transmit at 902.3Mhz)
 VM_WTRGAS_FCC_MID (transmit at 908.5Mhz)
 VM_WTRGAS_FCC_HIGH (transmit at 914.9Mhz)
The firmware file that will enable the module to hop in 64 channels between (902.3 and 914.9) is
named as follows:
 VM_WTRGAS_FCC_TXHOP_PWR1
Chirp Spread Spectrum
Chirp Spread Spectrum was developed for radar applications in the 1940’s. Traditionally used in a
number of military and secure communications applications; over the past twenty years this modulation
technique has seen increased adoption in a number of data communications applications due to its
relatively low transmission power requirements and inherent robustness from channel degradation
mechanisms such as multipath, fading, Doppler and in-band jamming interferers.
A CSS PHY was adopted by the IEEE for the Low-Rate Wireless Personal Area Networks (LR-WPANs)
standard 802.15.4 for applications requiring longer range and mobility than that achievable with the OQPSK
DSSS PHY mode.
LoRa Spread Spectrum
Semtech’s LoRa modulation addresses all of the issues associated with DSSS systems to provide a low cost,
low-power, yet above all robust alternative to the traditional spread-spectrum communications
Techniques.
In LoRa modulation the spreading of the spectrum is achieved by generating a chirp signal that
continuously varies in frequency. An advantage of this method is that timing and frequency offsets
between transmitter and receiver are equivalent, greatly reducing the complexity of the receiver design.
The frequency bandwidth of this chirp is equivalent to the spectral bandwidth of the signal.