FlightAware Discussions

Antenna optimization command line tool

Hi there,

is there a realtime tool available which i can launch during antenna position testing?
I would like to check if the message rate is going up or down without waiting for the next stats graph.

Some positions are not easy to hold the antenna for > 5 Minutes, i am not a very sportive guy :slight_smile:

Shall i try it with the Planefinder client which does have a realtime dashboard?

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Short answer - no.

As nothing else is constant (transmitter location, Tx power, reflections, noise), adding another variable won’t help you identify what has improved.

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I’m not sure what you are asking for if you already have a display of the message rate?

Average over 1 minute?

If you want the 1 hour graphs to update more often, you can do this:

while sleep 20; do sudo /usr/share/graphs1090/graphs1090.sh 1h; done

Note that it will still only update once a minute and the website only refreshes every minute as well. (independent of the new graph being present)

One Minute standing on a ladder while holding the arm with the antenna right up in the air can be very long :slight_smile:

So the message rate is a good indicator, correct?

I will adjust your script temporarily and check if it fits.

Short answer - no.

As nothing else is constant (transmitter location, Tx power, reflections, noise), adding another variable won’t help you identify what has improved.

I assume you did not get my question. I do not want to add a variable but getting an existing value which indicates me if an antenna is held in perfect position and this not only after minutes. Someting like a signal rate or like this.

But will try the method @wiedehopf suggested

The problem with this is the variability of ADS-B over short periods. It’s going to be quite hard to fine tune an antenna position by looking at the instantaneous message rate. Regression to the mean is the type of error you will get - a temporary increase or drop in message rate coinciding with you moving the antenna can look significant, but actually not make a difference or give the opposite outcome over the long term.

Temporarily fixing the antenna in place and waiting to collect results is pretty much the only way to evaluate performance. It’s a slower process but is more likely to give a definite outcome.

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OK, thanks

let’s see if i can ask my wife holding the antenna on the ladder :slight_smile:

Can’t you clamp it to the ladder somehow?

Or suspend it via non-metallic string?

Sure, will find a solution. I thought it is a bit easier, but anyhow…

Im sure she’ll be delighted to, no doubt about that :+1: :wink:

[quote=“biekerc, post:9, topic:53270”]
Im sure she’ll be delighted to, no doubt about that
[/quote]Sure, but it’s all about the price to pay :wink:

I got your question, you didn’t get my answer.

The antenna position is the ‘variable’ I was referring to.
At 900km/h, a plane travels 1/4 kilometer per second.
After 1 minute, signal strength and message rate may have changed dramatically. Attributing this solely to one variable is just silly.

The only meaningful comparison you can do it to setup a second ‘reference’ receiver and compare the two.

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That is why AGC does not work, it is not one signal you can tune to, but many and constantly changing.

I experimented a bit with antenna placement in an attic. Higher up was better, and not to close to any walls. Placing it in areas with just the clay roof tiles and no further insulation improved reception in those directions, but made it worse in others.

Now i got it, thanks
My second “reference” is not built, so i need to bring my idea about my wife in again :slight_smile: