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Patch Antenna Ground Plane - Increase Performance

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That would test the performance difference between the two rx's, along with their antennas. That's a fine thing to do. But for testing the ground mounted versus tripod mounted antenna (the basis of this discussion), the A/V rx's and the two antennas would need to be closely matched to correctly qualify the results. So, that is why I recommend that you test each antenna on its own merit.

Edit:

Glad to see you are using the Oracle. It has a very nice manual mode that will allow you to make convenient comparison evaluations between the two systems.

Edited by Mr.RC-Cam
Oracle manual mode.

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That would test the performance difference between the two rx's, along with their antennas. That's a fine thing to do. But for testing the ground mounted versus tripod mounted antenna (the basis of this discussion), the A/V rx's and the two antennas would need to be closely matched to correctly qualify the results. So, that is why I recommend that you test each antenna on its own merit.

Of course. Variation in the Rx=another variable. Like you say "with microwaves everything matters".

So for a proper test, I should eliminate the diversity box and just use one Rx and one antenna. With the balloon holding the Tx relatively constant, I can just record the video while trying different antenna positions, and then just edit the recordings to make side by side comparisons.

Unless, you can recommend an affordable way for me to measure the video signal.

Back to the idea of using the oracle to measure the signal differences- I could control for Rx variables by switching the Rx's from the tripod ant. to the ground ant. so that I could get a reading from both combinations.

Edited by Photon

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So for a proper test, I should eliminate the diversity box and just use one Rx and one antenna.

Just retain the Oracle and put it in the manual mode. Then use it to switch between the two A/V systems. That way you can test each system, on the fly, without any fuss. Otherwise, you have to stop what you are doing, unplug the one system and connect the other. You've got the Oracle, so you might as well use all its handy features.

With the balloon holding the Tx relatively constant, I can just record the video while trying different antenna positions, and then just edit the recordings to make side by side comparisons.

That will provide some subjective information. If you want to quantify the results, you'll need to put a voltmeter on the Rx's RSSI and make measurements as you change Rx antenna elevations. You'll also want to test at various distances too (long distances are much more useful than tests made in close proximity).

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I'm with you on using the Oracle's manual mode, I even thought about using the video level adjust mode to compare the two signals back and forth rapidly:)

This still leaves the extra variable of the two Rx's in the mix. Wouldn't it better to just use one antenna and one RX so that the only variable would be the antenna position?

I thought that I would have an assistant move the Tx away from the ground station until the signal degraded, and then play with the antenna position looking for improvements. Since I'm not having to worry about flying the Tx, there is no problem messing around with the Rx.

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This still leaves the extra variable of the two Rx's in the mix. Wouldn't it better to just use one antenna and one RX so that the only variable would be the antenna position?

That is exactly what I mean. While in manual mode, after you are done testing one antenna/Rx at the various elevations, press the Oracle's front panel switch, and then test the other. No cables to swap, no fuss.

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To measure RSSI, can I just take a DC voltage read between the two conductors of the RCA video out on the Rx? If so, what kind of range should I expect? I'm using the generic import 12v Rx.

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No, RSSI is an internal signal, you need to tap inside the receiver to find it.

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No, RSSI is an internal signal, you need to tap inside the receiver to find it.

I figured it would have to be more complicated :( . All the stuff I have found, has been related to data networks, and it appears they measure RSSI with software. Can you give me any links that will clue me and my multimeter in? What is the Oracle measuring when it compares the video signals?

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The Oracle dose not use RSSI, it uses clever software to check the video signal and decide when to switch.

Terry

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