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Old Sep 06, 2012, 07:40 PM
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Originally Posted by freechip View Post
They represent antennas, Two of them are main and then other two are sat antennas.

Forget which is which.
This is another area where I am frustrated by a lack of detailed product information. In this case, I have a main and a sat receiver. Both have two "antenna wires" protruding from them. From the telemetry data (only two of the four slots have non-zero data), I infer that both receivers are single diversity and that the antenna on each receiver is a dipole. But this is not very well explained in most of the pre-purchase information available. Aren't there some receivers out there that are dual diversity PER RECEIVER and that what would appear to be a dipole antenna is in fact two monopoles?

I'd really like to see us all standardize on terminology.... the separate boxes connected by the three conductor cable are RECEIVERS, not "antennas". The wires protruding are the ANTENNAS. Some receivers have two independent antennas (dual diversity) and some have one (single diversity). A single antenna can be one wire or two. This might sound like a nit pick, but it has importance if we are supposed to fully understand how our radios work and understand what to expect from the various versions.

Paul
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Old Sep 06, 2012, 07:50 PM
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Also,

How many frames are significant? I saw a video where someone mentioned (in passing) that you can have more frame losses on DSMX that DSM2. That number was (i believe) 120-140 on X before you need to worry.

Is there a scale??
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Old Sep 06, 2012, 09:10 PM
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Originally Posted by idletime View Post
Also,

How many frames are significant? I saw a video where someone mentioned (in passing) that you can have more frame losses on DSMX that DSM2. That number was (i believe) 120-140 on X before you need to worry.

Is there a scale??
Just off the top of my head, I am not too concerned about just about any number of scattered and non-contiguous lost frames. Each individual lost frame by itself is so brief that you probably would not notice it in flight since it will only introduce a brief (22mS?) delay in control response if it is followed by a valid frame. However, continuous and contiguous lost frames sufficient to trigger a HOLD is an issue.

Paul
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Old Sep 06, 2012, 09:47 PM
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Andy,

Did you change the sampling or averaging of RX voltage telemetry data in the latest DX8 firmware? A model began reporting frequent minor RX voltage fluctuations after I updated my DX8.

Previously, an RX voltage alarm value of 4.7V avoided alarms in flight. The min/max display would indicate 4.9/5.0, and occasional 4.8/5.0. It's been stable for hundreds of flights.

After updating firmware, the next flight it began to alarm in brief bursts as soon as it became airborne. The min RX voltage value logged was 4.7V. Reducing the alarm point to 4.6V avoids the alarms. The DSM2 RX LED didn't blink during six flights.

It's not a major change, but noticeable.
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Old Sep 06, 2012, 09:56 PM
AndyKunz's Avatar
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No change to telemetry other than to enable a few new sensors.

The receiver shouldn't blink until around 3.5V IIRC.

I would check the aircraft and its power system if you notice a change.

Andy
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Old Sep 06, 2012, 10:04 PM
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Quote:
Originally Posted by pgoelz View Post
This is another area where I am frustrated by a lack of detailed product information. In this case, I have a main and a sat receiver. Both have two "antenna wires" protruding from them. From the telemetry data (only two of the four slots have non-zero data), I infer that both receivers are single diversity and that the antenna on each receiver is a dipole. But this is not very well explained in most of the pre-purchase information available. Aren't there some receivers out there that are dual diversity PER RECEIVER and that what would appear to be a dipole antenna is in fact two monopoles?

I'd really like to see us all standardize on terminology.... the separate boxes connected by the three conductor cable are RECEIVERS, not "antennas". The wires protruding are the ANTENNAS. Some receivers have two independent antennas (dual diversity) and some have one (single diversity). A single antenna can be one wire or two. This might sound like a nit pick, but it has importance if we are supposed to fully understand how our radios work and understand what to expect from the various versions.

Paul
I heartily second your plea for clarity and specificity when we are discussing these components. There are too many complex issues already for us to deal with, without muddying the waters by imprecise language. I also believe you have accurately described the correct nomenclature for the various bits.
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Old Sep 07, 2012, 01:04 AM
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Originally Posted by AndyKunz View Post
No change to telemetry other than to enable a few new sensors.

The receiver shouldn't blink until around 3.5V IIRC.

I would check the aircraft and its power system if you notice a change.

Andy
Keeping an eye on this model's BEC was the sole reason telemetry was installed. Flight pack, ESC temp and RPM were fringe benefits to gaining RX voltage. I still use the timer, rather than flight pack voltage, to determine flight length.

During all six flights the lowest RX voltage was only 0.1V to 0.2V lower than usual, but occurred frequently. That's why I thought the change might be related to firmware changes.
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Old Sep 07, 2012, 07:53 AM
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Originally Posted by tracknoob View Post
I heartily second your plea for clarity and specificity when we are discussing these components. There are too many complex issues already for us to deal with, without muddying the waters by imprecise language. I also believe you have accurately described the correct nomenclature for the various bits.
This is even more important when it comes to doing a post mortem after an incident. Once you understand exactly how the system is supposed to operate, it is easier to figure out what might have contributed to the incident.

But back to the radio and its documentation..... after a flight yesterday, the flight data showed an "A" = 16, "B" = 0, "L" = 4, "R" = 0, "F" and "H" were zero. From this I deduce that one receiver had 16 instances where it lost the transmitter and the other receiver had four. There were no instances where both receivers lost the transmitter simultaneously. Good so far..... I had perfect control. However, I have no idea which receiver might need to be re-oriented since I can't find any reference to which receiver is associated with which set of numbers. The main RX is oriented horizontally and the sat is vertical. I'm guessing the horizontal RX is the one with the most fades, but..... Andy, can you help? This really should be in the manual.

Paul
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Old Sep 07, 2012, 08:10 AM
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A = main receiver

L = Sat

But with those numbers you are worrying too much.

A - Antenna fades on internal antenna A
B - Antenna fades on internal antenna B (not used on the AR8000)
L - Antenna fades on the left external antenna
R - Antenna fades on the right external antenna (not used on the AR8000)
F - Frame loss
H - Holds

• Holds—Holds are unacceptable. If a hold occurs, please investigate and correct
the issue before next flight.
Frames—<100- In conventional models during a 10 minute flight, frames
should typically be less than 100 on all receivers
.
• Fades—Use Fades for comparison only. All attached receivers should have
similar Fades. If not, investigate poorly performing receivers (location, antenna
orientation, etc) and correct.

Operational Differences between DSM2™ and DSMX® receivers while
using the Flight Log:
DSMX is frequency agile while DSM2 finds two quiet channels and remains
on those channels. Consequently, because DSMX operates on quiet and noisy
channels, it’s common to have more Antenna Fades and Frame Losses than when
using DSM2 in busy 2.4GHz environments
.
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Last edited by freechip; Sep 07, 2012 at 08:18 AM.
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Old Sep 07, 2012, 08:21 AM
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Quote:
Originally Posted by freechip View Post
A = main receiver

L = Sat

But with those numbers you are worrying too much. Over 200 then you start looking at orientation.

A - Antenna fades on internal antenna A
B - Antenna fades on internal antenna B (not used on the AR8000)
L - Antenna fades on the left external antenna
R - Antenna fades on the right external antenna (not used on the AR8000)
F - Frame loss
H - Holds
Thanks. That confirms my suspicion re: orientation.... the main receiver has the horizontal antennae. And no, I'm not really "worried". Just pointing out that from the documentation I have found, I would have no way of knowing what to re-orient if I WAS worried. Given the nature of antenna behavior and propagation at 2.4GHz, I'm actually surprised the individual receiver numbers are as low as they are.

I seem to recall reading somewhere the same info that you posted, but when I looked for confirmation, I was surprised that I wasn't able to find it in the manuals or on the Spektrum site.

EDIT: Andy (and others at Horizon / Spektrum).... I apologize if any of this seems harsh or whiney. I'm just looking for more complete system information in the available documentation so I can make educated choices when setting up and also when evaluation "incidents". I fully and totally appreciate the direct access to the developers and code writers that we enjoy here. I have to assume that is not the case with Futaba.

Paul
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Old Sep 07, 2012, 08:31 AM
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It's in the DX8 Manual on Page#42 You get some indication they just used the stand alone Fligh Log wording.

Quote:
Originally Posted by DX8 Manual
Using A Flight Log —Optional
The Flight Log (optional) is compatible with the AR8000 receiver. The Flight Log displays overall RF link performance as well as the individual internal and external receiver link data. It also displays receiver voltage.

Using the Flight Log
After a flight and before turning off the receiver or transmitter, plug the Flight Log into the Data port on the AR8000 receiver. The screen will automatically display voltage i.e. 6v2= 6.2 volts. Note: When the voltage reaches 4.8 volts or less, the screen will flash indicating low voltage.
Press the button to display the following information:
A - Antenna fades on internal antenna A
B - Antenna fades on internal antenna B (not used on the AR8000)
L - Antenna fades on the left external antenna
R - Antenna fades on the right external antenna (not used on the AR8000)
F - Frame loss
H - Holds

Antenna fades—represents the loss of a bit of information on that specific antenna. It’s normal to have as many as 50 to 100 antenna fades during a flight. If any single antenna experiences over 500 fades in a single flight, the antenna should be repositioned in the aircraft to optimize the RF link.
Frame loss—represents simultaneous antenna fades on all attached receivers. If the RF link is performing optimally, frame losses per flight should be less than 20.
A Hold- occurs when 45 continuous frame losses occur. This takes about one second. If a hold occurs during a flight, it’s important to re-evaluate the system, moving the antennas to different locations and/or checking to be sure the transmitter and receivers are all working correctly.
Note: Use a servo extension to allow the Flight Log to be plugged in without having to remove the aircraft’s hatch or canopy. On some models, the Flight Log can be plugged in, attached and left on the model using double-sided tape. It is common with helicopters to mount the Flight Log to the side frame.
And this is based on DSM2 because at the time DX8 was released DSMX was not yet public.

There is another document that talks about the specifics of DSMX.
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Old Sep 07, 2012, 08:35 AM
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Quote:
Originally Posted by pgoelz View Post
This is another area where I am frustrated by a lack of detailed product information. In this case, I have a main and a sat receiver. Both have two "antenna wires" protruding from them. From the telemetry data (only two of the four slots have non-zero data), I infer that both receivers are single diversity and that the antenna on each receiver is a dipole. But this is not very well explained in most of the pre-purchase information available. Aren't there some receivers out there that are dual diversity PER RECEIVER and that what would appear to be a dipole antenna is in fact two monopoles?

I'd really like to see us all standardize on terminology.... the separate boxes connected by the three conductor cable are RECEIVERS, not "antennas". The wires protruding are the ANTENNAS. Some receivers have two independent antennas (dual diversity) and some have one (single diversity). A single antenna can be one wire or two. This might sound like a nit pick, but it has importance if we are supposed to fully understand how our radios work and understand what to expect from the various versions.

Paul
I personally don't like the term "single diversity". It's like describing your marital state as monogamist polygamist. The term "diversity" shouldn't be used until there are multiple signal pathways, just as the term "polygamy" should not come into play until there is more than one spouse.

Just one man's opinion...

Doug
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Old Sep 07, 2012, 08:48 AM
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Quote:
Originally Posted by freechip View Post
It's in the DX8 Manual on Page#42 You get some indication they just used the stand alone Fligh Log wording.

And this is based on DSM2 because at the time DX8 was released DSMX was not yet public.

There is another document that talks about the specifics of DSMX.
Thanks! No wonder I didn't find it.... I was looking in the "telemetry" section

And to Doug..... agreed that "single diversity" is kind of an oxymoron now that you point it out. Maybe "non-diversity" would better describe a single antenna system (dipole or monopole). Just another example of how we need to refine our vocabulary when dealing with a complex system like the Spektrum radios.

Paul
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Old Sep 07, 2012, 09:22 AM
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Joined Apr 2008
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Log trigger DX8

Hello,

I installed V2.05 on my DX8. I'm using an electric heli an programmed the throttle channel to a switch (using gov mode of ESC). I set the log trigger to Throttle and set the value to 10%. When I start the motor, the logging is not started. When moving g the pitch stick a little bit upward the logging seems to start (I can hear a click from the beeper).

So it seems that log trigger is not really on throttle channel, it seems it is fixed to pitch stick (which is normally connected to throttle for nitro heli).

Is this a bug or a feature?

Kind regards

Michael
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Old Sep 07, 2012, 09:34 AM
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Canada, ON, Rockland
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Quote:
Originally Posted by pgoelz View Post
Thanks! No wonder I didn't find it.... I was looking in the "telemetry" section ...
On newer DSMX radio like the DX6i for example, this information is found at the begining of the manual.

Quote:
Originally Posted by DX6i MANUAL PAGE#4
Flight Log Recording - Fades Higher than DSM2
Note that DSMX hops through the band while DSM2 finds two
quiet channels and remains on those channels. Consequently
because DSMX operates on quiet and noisy channels, it’s common
to have more Antenna Fades than when using DSM2
, when
used in busy 2.4GHz environments. When taking flight log data
readings, the Frames and Hold Data are important and should be
used a reference while Fades are insignificant due to the nature
of frequency hopping.
A 10-minute flight will typically result in
less than 50 Frame Losses and no Holds.
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