User's Manual

UtiliNet® Endpoint User Guide 11-1-2006

Page 25 of 30

It is apparent that this link of 5 miles distance, under the conditions described, should be very reliable

because you were able to include a conservative multipath factor and a margin of safety, and still have the

link budget balance. If the end application allows links with less than ideal margin and reliability, much

larger distances may be spanned. A large Southern California installation consisting of thousands of

UtiliNet Series I radios with 0 dBd antennas was surveyed. The terrain varied from hilly to flat, and the

antennas varied from up high to down low. The result was that the distance between radios that were able

to communicate was an average of 5.3 miles. The distribution over ±1 standard deviation was 3 to 11

miles!

The official UtiliNet radio distance record to date (using Series I UtiliNet radios) is between Mt. Vaca (near

Sacramento, CA) and Loma Prieta Peak (South of San Jose, CA): a distance of almost 89 miles. Using 3 dB

omni-directional antennas, with cavity-type bandpass filters to protect against interference, this line-of-

sight link runs with about a 30% data success rate.

Keeping a Check on Interference

Ideally, a radio receiver should be able to process a very weak signal in the simultaneous presence of

Megawatt signals within adjacent frequency bands. Such strong adjacent signals would be rejected by the

receiver filters. In practice, however, there are practical limitations. The ratio of desired versus undesirable

signals is referred to as the Dynamic Range of the receiver. Receiver system design involves the following

trade-offs.

• Rx sensitivity versus dynamic range