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Advanced PCM Range Testing
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Posted: Saturday, March 24, 2001
Provider Name:
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Variables
| VARIABLES THAT AFFECT RESULTS |
Besides the basic equipment-related issues that affect the core of range testing (receiver tuning, TX tuning, antenna placement, etc.) there are a significant number of variables which will affect the number you receive - all of which point to using the same location, the same methodology, if you are going to measure performance on a year-to-year basis. Here's a few we're aware of.
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| Type |
Significance |
Why |
| Surface type |
Significant |
At a local private airport, we tested models on the closely-cropped grass. At the extreme end of the range, we then walked onto the center of the runway - and proceeded to get 20-30% more range consistently. So the surface over which you test your model DOES make a substantial difference. Grass gives shorter numbers than blacktop. |
| Model height |
Significant |
Usually, for convenience, we put models on the ground. However, depending on the size and placement of the receiver in the model, we usually see an increase when the model is placed on a non-metallic table. Needless to say, this more accurately reflects the model's actual flight conditions. However, it's important that the table be sturdy enough to handle engine-on testing. |
| Transmitter height |
Somewhat significant |
When you reach the limits of range, a transmitter that is low will have less range than one that's held overhead. Holding your arm out horizontally removes a variable. |
| Surface slope |
Significant |
We discovered that a sloped surface can affect range. When the transmitter was below the model, we measured less range than when the transmitter was above the model. In the case we tested, our range varied by about 20% simply by swapping position of the TX and model. |
| Modeller proximity |
Potentially significant |
We've found that often, the location of a modeller's hand around the fuselage where the receiver antenna is located will increase range falsely. It seems that if modellers are standing around, there is no significant change. But having someone hold your model around the antenna is not optimum. |
| Transmitter/Receiver voltage |
Insignificant |
Common sense would dictate that higher voltage would improve range, but it just isn't so. We did a range test with a 10X that was beeping due to low voltage (8.9 volts) and found the range to be virtually identical to an 11 volt transmitter. Voltage of the receiver pack also had no affect on range.
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Written By:Eric Meyers
Copyright: © 2001 Horizon Hobby, Inc.
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