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Old Oct 18, 2013, 01:38 PM
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JOddino's Avatar
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Antenna Data

Has Jeti or anyone posted any info describing the significance of the antenna data logged with the new software? We see a number from 1 to 10 for each antenna and a percentage for the quality. I have seen numbers as low as 4 and 5 on the antennas and 80% on the Q.

Are these numbers related to the uplink or are they measurements of the downlink from receiver to the transmitter? How is the percentage determined? Number of packets good in some length of time? What is the length of time? Are there RF industry standards for these parameters?

A little more information describing these numbers would make them a lot more useful.

Jim O
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Old Oct 19, 2013, 08:33 AM
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Although I understand were you are coming from with your questions on antenna numbers on the intrinsic knowledge, could you explain what difference it would make? Unless I am missing the point I see those number as an indication of the signal "cleanliness " of my installations.

1) The number should be "9" on at least one antenna when I am close by and changing the orientation of my plane/heli/multi. If it is less than that my installation needs rethinking.

2) When I move away the numbers can move down but should not be in the "0"/"1" range

3) If my alarm goes off (which I have set a "2") during flight I should either get closer or land

Might be simplistic but if the numbers were in percentage/wavelength...it would still give me the same indications.
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Old Oct 19, 2013, 01:06 PM
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Originally Posted by Puttputtmaru View Post
Although I understand were you are coming from with your questions on antenna numbers on the intrinsic knowledge, could you explain what difference it would make? Unless I am missing the point I see those number as an indication of the signal "cleanliness " of my installations.

1) The number should be "9" on at least one antenna when I am close by and changing the orientation of my plane/heli/multi. If it is less than that my installation needs rethinking.

2) When I move away the numbers can move down but should not be in the "0"/"1" range

3) If my alarm goes off (which I have set a "2") during flight I should either get closer or land

Might be simplistic but if the numbers were in percentage/wavelength...it would still give me the same indications.
I'd like to know if I am losing commands to the airplane or losing TM data from the airplane. I'm not worried if I am losing TM data but I would be concerned if I am losing a significant number of commands and for how long. It I lose a frame now and then it is not a problem. If I lose many consecutive frames, I'd want to do something about it. At one time I was led to believe this information applied to the downlink and the uplink was significantly more robust. If this is true we can all quit worrying.

Of course the most important thing is to get a baseline of what the numbers are when the system is performing properly so you can detect any degradation before it gets too bad and crashed you. I'm convinced I would not have crashed and burned a $4000 airplane a few years ago, if my Futaba system had this capability. And by the way, there were 18 fire trucks and two helicopters called in to put out the fire. They saved the Malibu coast though.

Jim O
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Old Oct 19, 2013, 04:16 PM
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A legitimate and very well explained concern, thanks for clarifying it. I am with you on the need to define this
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Old Jan 26, 2014, 01:27 AM
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JOddino

I asked the same question of the distributor. Their comment was "don't worry about it. I use it on my expensive jet setups." Hmmmm. Guess he didn't understand that he doesn't pay for MY planes. I have seen my reception fade to 50% of optimum in certain instances.

To answer your question, the measurement is supposed to be the downlink. As was explained to me, it is a measurement or report of the signal strength coming back to the TX and not the true measurement of the signal going to the aircraft for it's control. Kinda like it's "second hand information". So, in theory, the signal going from the TX to RX is stronger and more precise and the signal coming back to TX is a telemetry type report. This would suggest that your reading could show a weaker signal than is actually going to the aircraft.

Now this could all be true or they could be blowing smoke to mask any issue of poor reception. I think the fix is "insurance". Give us multiple antennae placements (RX satellites) without having to buy multiple RX's. Either that or (better yet), make Jeti TX's compatible with generic RX's so we can use other RX's that DO have the redundant antennae placements. Wouldn't that set the market on fire for Jeti?

Jeti's TX weakest link is their RX. Not that they are bad RX's. Just not enough antennae. In all fairness, I have not lost control of an aircraft despite the occasional 50% signal bars.
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Old Jan 26, 2014, 12:27 PM
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....
Jeti's TX weakest link is their RX. Not that they are bad RX's. Just not enough antennae. In all fairness, I have not lost control of an aircraft despite the occasional 50% signal bars.
Most 2.4ghz antennas used in rc RXs have the same activate length. About 25mm. Only that last bit affects receiption, the yellow shrink tube section in jeti's case. It is no different for futaba or others. The rest on the length is coax cable. There is no reception in that section. That cable length offers you flexibility to position and orient the activate end section only. If fact, the longer the coax section, the higher the power losses due to attenuation.
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Old Aug 19, 2014, 06:53 AM
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Most 2.4ghz antennas used in rc RXs have the same activate length. About 25mm. Only that last bit affects receiption, the yellow shrink tube section in jeti's case. It is no different for futaba or others. The rest on the length is coax cable. There is no reception in that section. That cable length offers you flexibility to position and orient the activate end section only. If fact, the longer the coax section, the higher the power losses due to attenuation.
All true. But positioning the antennae end is important and more difficult if the coax is so short. And having more than two ends (satellite RX) gives us better chances of reception with a big and complicated aircraft. But in all fairness to Jeti, I believe their components are of very high grade and I seldom get lower signals even with two short antennae.
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Old Aug 19, 2014, 07:28 AM
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Originally Posted by Brotozoa View Post
All true. But positioning the antennae end is important and more difficult if the coax is so short. And having more than two ends (satellite RX) gives us better chances of reception with a big and complicated aircraft. But in all fairness to Jeti, I believe their components are of very high grade and I seldom get lower signals even with two short antennae.
Lol!
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