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Relationship Between GPS and Canopy RF

The GPS signal is used to enable Time Division Duplexing (TDD) within the Canopy system. This is a very effective way of radio transmission for data. It is very commonly used with cellular phone networks. Using GPS as a common clock, all Canopy radios transmit and receive data at common intervals. Since this occurs over the same RF channel the radios are half-duplex.

The GPS signal is used because it is a worldwide clock. This way all Canopy radios are transmitting at the same common intervals regardless of their geographic location. If a Canopy radio is set to Generate Sync, then it is transmitting at a different cycle then a Canopy with GPS sync. The most common result is data packet loss and degradation over time.

GPS and the RF Signal Strength
It has been thought that the GPS affected the RF section of the Canopy. That it was related to the signal strength, or the GPS turned on and off the RF section completely. This is simply not the case. The RF section is always on and the GPS only affects the data transmission cycle. Without a GPS sync or generating a sync the Canopy will not transmit at all.

Canopy RF Spectrum
TDD is highly favorable because of the amount of frequency spectrum that each Canopy unit covers. A full Canopy RF signal covers almost 40MHz in the 2.4GHz, 5.2GHz, and 5.7GHz frequency bands. This is why GPS, and frequency coordination, and frequency layout are a critical step in the design of a Canopy network. Having GPS installed throughout the network will insure that all radios are in unison.

Where to install GPS
To insure proper use of TDD, a GPS device is required at all Access Points and Backhaul Master locations of the same frequency band. This includes remotely installed access points. It is possible to pass the sync from a Subscriber Module, or Backhaul Slave and will function effectively. However, it will cause a slight delay in transmission. This method is only recommended for a single Canopy unit installed at a single location.

Powerpoint Presentation
Download a Powerpoint presentation outlining the features of the Mini-GPS and the relationship of the GPS, TDD, and Canopy RF.

Powerpoint Presentation