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FASST, FHSS Ranges

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Old 11-16-2012, 12:47 PM
  #76
TFF
 
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Default RE: FASST, FHSS Ranges

Protocol is really not what the question is; it is how powerful the radio part is. How far can it send the protocol. The output ,according to the antenna formula there, is 1/2 for the FHSS with the same 100mw input. 30 Years ago MRC unboxed one of their ARF trainers and flew it to 3400ft with a standard cheapy AM radio. Some one took some radios up in their airplane with a TX operator on the ground. The Kraft 5 channel won the altitude contest, but I think the 2.4 stuff was about 500 or so lower. Not really far off. I want to know what the fudge factor distance is. The AMA probably loves limited range to keep us out of the hair of the FAA. I just want to know worst case range. I dont think there is a problem with an 8J; still thinking of buying one.
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Old 11-17-2012, 09:31 AM
  #77
Four Stroker
 
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Default RE: FASST, FHSS Ranges

With the original FASST, I have gotten 600 feet in a power down range test. The range test mode is 23 dB down (measured on TM14). So range test mode is LESS THAN 1 MW. You don't really need a lot of power. The bit rate of space probes and satellites has gone up by three orders of magnitude in the last 40 years - DUE ENTIRELY TO BIT ERROR DETECTING AND CORRECTING PROTOCOLS (and modulation techniques). So if a manufacturer of RC stuff knows what they are doing, they can get more range with 10 mW than a stupid system design with a watt.
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Old 11-25-2012, 07:40 PM
  #78
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Default RE: FASST, FHSS Ranges

Looking at your last picture.
Both antennas are more or less parallel to each other, and one is in proximity to the metal end of the servo rod.
What I would do.
Move the receiver a little bit farther back, so that the antenna closest to the servo rod is a bit farther away from the metal portion.
One or the other of the antennas should ideally be vertical, the other horizontal, likely close to the bottom of the fuselage.
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Old 11-26-2012, 04:59 AM
  #79
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Default RE: FASST, FHSS Ranges

Power output is one thing.

You can scream at our old deaf grandma or your young daughter with the same high pitch voice. Right, you will notice a difference.

Therefore, one of the most important parameter is receiver sensitivity measured in (-) dBm.

Standard 2.4GHz transceivers come with -93 dBm. I don't say is like a deaf grandma but what you want for top range is something around -106 dBm. Top class receivers have pre-amplifiers soldered onto the PCB to achieve this.

Now, the question is what the sensitivity of the FASST and FHSS-S receivers really is.
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Old 11-26-2012, 11:49 AM
  #80
falcon_56
 
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Default RE: FASST, FHSS Ranges

Interesting FAQ question with regards to range between FASST and S-FHSS (6EX and 6J respectively)

http://www.futaba-rc.com/faq/faq-6j-2_4ghz.html#q1175

Quote:
Could you give me an estimate of how the range of the 6J compares with the 6ex 2.4 ghz under similar condition. No antenna on the 6J is somewhat worrying.

Yes, it has the same range, even without a visible antenna as the 6EX FASST.

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