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Published on December 3, 2012
During the development of our latest RAMP module, the RM024, we broke out of our florescent-lit Kansas office to enjoy some of the nice weather and put our new RAMP module, the RM024, through its paces. Specifically we wanted to do some real-world range testing and compare the RM024 with the LT2510, which it will be succeeding.
The LT2510 is one of our best-selling and best-performing RAMP modules. It offers a good mix of throughput, range and power consumption and works for a variety of machine-to-machine applications. The RM024 is based on the same core processor as the LT2510, so we knew the throughput would be the same. Because the RM024 has a new low-noise amplifier and power amplifier, wanted to make sure it performed as well or better in all scenarios. We previously tested the power consumption in the lab and the RM024 lowered the maximum current at 3.3 V from 190 mA to 166 mA, a 12% reduction.
For our range test we used an online tool to identify a good location near our office that would afford good line-of-sight conditions. Located in the central United States on the Great Plains, Kansas often gets a reputation for being very flat, but near our offices in the eastern part of the state we have an uneven terrain with small rolling hills with lots of trees. This makes long line-of-sight tests difficult, but if you can find the right location— between two hills— you can simulate a test that normally would be performed with tall antennas. For our test we found a four-mile stretch (4.1 miles actually) which featured one small hill in between two larger hills. Our new RM024 compared very favorably with the LT2510 and matched or bettered its performance in our test. We had 100% packet throughput (with the default of three retries) at 4.1 miles using 5 dBi antennas.
The image below is a screen shot from http://www.heywhatsthat.com/, a nice site which can provide line-of-sight calculations based on elevation information. The area with the X is the where we placed the Client radio and the red areas are the places where heywhatsthat.com estimates we would have line-of-sight conditions. In reality, conditions are different due to cars, signs, trees, and bridges which are not captured in their estimate; but it’s still a good starting point. The green line shows where we had connectivity for the RM024. We did slightly better than the estimated line of sight, but line of sight is still important for radios operating at 2.4 GHz, especially when operating outside over long distances.
Later, we drove a little further and tested at 5 miles. The RM024 was still getting very reliable data, but it didn’t meet the 100% packet throughput we were looking for, so we’ll stick with 4.1 miles as the official range test.
The RM024 is available now in both surface mount and pluggable options, it features an RF switch which allows for using either an external antenna or the onboard chip antenna. . In addition to the hardware changes, look for a number of exciting new features which will establish the RM024 as the go-to solution for long-range 2.4 GHz applications.