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Old Sep 30, 2013, 10:44 PM
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OpenLrs and 1.3 vtx/vrx

Hi guys, I been trying to find info about this so I don't have to bother anyone, but I had no luck...

So, I currently have a quad with 1.3 vtx/vrx from readymaderc with saw filter rx antenna is a blue mushroom and 3 turn helical for the vrx, both right hand, Been using my quad with a 2.4 futaba FASST rx until I noticed I lost signal and recovered with no incident, I tested using the futaba low power fail safe to see with the vtx on and off, while on, I was able to walk about 50 steps away while when off, 90 steps... So I was about to buy a low pass filter when all the sudden I was recommended to move to uhf better... So I researched and decided to go with openLrs 1w which I love the fact it comes with telemetry, now, I imagine the 3rd harmonic might still cause issues and I might have to learn as I go, but trying to prevent, I am hoping you guys have the experience and can tell me what is the right thing to do? Well it be Ok to try without a low pass filter? At this point, will the vtx scream over my lrs rx? Or will my Lrs tx scream over my GS VRX?

Is there anything else I should acquire to have a safe flight and to make sure my video nor my range is affected?

Both, the openlrs tx and rx are programmed with OpenLRSng 3.0.

I am including a few pictures of my setup, If there is anything else I should be concerned, let me know, I will appreciate it!

Fabio
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Old Oct 01, 2013, 03:29 PM
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Are you running an OSD? If so, you'd probably be better off sending RSI to the OSD than using the openLRS telemetry as it cuts the data rate and the RX has to transmit, since the rx is 100mw only your receiver range will be farther than you can receive telemetry anyway.
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Old Oct 01, 2013, 07:20 PM
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Originally Posted by ianferrell View Post
Are you running an OSD? If so, you'd probably be better off sending RSI to the OSD than using the openLRS telemetry as it cuts the data rate and the RX has to transmit, since the rx is 100mw only your receiver range will be farther than you can receive telemetry anyway.
Hi ianferrel, i have a very cheap osd that only gives me battery voltage info, it is the Hobbyking e-osd... What osd would you recommend? I don't really understand much about the telemetry just yet, but when you say because rx it's only 100mw, my range will be farther than the telemetry can receive, what exactly do you mean? Now, how far do you believe I can travel with telemetry on, and how far plugging the RSSI to the osd?

Thanks!
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Old Oct 01, 2013, 10:29 PM
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He means that your UHF TX is 1 watt, while the RX that will be sending telemetry data back is only 100mw, so you will jave control of the craft much further out than the telemetry information can make it back to you. Better to use an OSD that shows that information than use the telemetry feature of openlrs when for long ranges it won't actually be useful anyway. As to which OSD, i have no opinion yet as i'm still putting together my first fpv setup.

As to filters, frequencies don't have harmonics lower than themselves, so you won't need to filter the vtc from the uhf rx. You will however need a filter on the uhf tx to prevent interfering with the vtx in your ground station, which on 1.2 can be pretty severe depending on the specific channel. 1280 is the worst i believe.
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Old Oct 01, 2013, 11:08 PM
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He means that your UHF TX is 1 watt, while the RX that will be sending telemetry data back is only 100mw, so you will jave control of the craft much further out than the telemetry information can make it back to you. Better to use an OSD that shows that information than use the telemetry feature of openlrs when for long ranges it won't actually be useful anyway. As to which OSD, i have no opinion yet as i'm still putting together my first fpv setup.

As to filters, frequencies don't have harmonics lower than themselves, so you won't need to filter the vtc from the uhf rx. You will however need a filter on the uhf tx to prevent interfering with the vtx in your ground station, which on 1.2 can be pretty severe depending on the specific channel. 1280 is the worst i believe.
Thanks for making it more clear... I am not planning to go to far, nor my battery time will allow it... but lets see how it goes. Do you recommend a specific filter for the uhf tx?
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Old Oct 02, 2013, 05:57 AM
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This would be a good one that's fairly cheap:
http://www.foxtechfpv.com/600mhz-low...ter-p-300.html
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Old Oct 04, 2013, 12:03 AM
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Are you in the US? If so, I believe the allowable frequencies are 420-450MHz. At 433MHz, the 3rd harmonic is 1299MHz. Too close to 1280 video. If you select your hop channels higher, between 445 and 450, that moves the 3rd harmonic to 1335-1350MHz. That should be far enough away so the video RX won't see it.
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Old Oct 04, 2013, 10:26 AM
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Are you in the US? If so, I believe the allowable frequencies are 420-450MHz. At 433MHz, the 3rd harmonic is 1299MHz. Too close to 1280 video. If you select your hop channels higher, between 445 and 450, that moves the 3rd harmonic to 1335-1350MHz. That should be far enough away so the video RX won't see it.
Thanks! great info! So, a newbie question! Do I change that in the OpenLRS tx and rx using the arduino? Doing that, will save me from having to buy the filter?
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Old Oct 04, 2013, 11:01 AM
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Originally Posted by fapelbaum View Post
Thanks! great info! So, a newbie question! Do I change that in the OpenLRS tx and rx using the arduino? Doing that, will save me from having to buy the filter?
No, change it using the google chrome configurator tool. Easy stuff.
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Old Oct 04, 2013, 11:56 AM
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No, change it using the google chrome configurator tool. Easy stuff.
Hi thanks for the great info! Just one more question! So when I switch to this new frequency you recommended, will the range be the same as if I was using the 433 without any video tx?
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Old Oct 04, 2013, 08:54 PM
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Hi thanks for the great info! Just one more question! So when I switch to this new frequency you recommended, will the range be the same as if I was using the 433 without any video tx?
Range should not be affected.

Edit: Are you asking if the change in frequency will affect your RC range or will the video TX affect your RC receiver less? The change in frequency alone should not affect your RC range, it will only help with your RC transmitter affecting your video receiver on 1280MHz. If your Vtx is affecting your RC range, changing the frequency will not help that. These are two separate issues.
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Old Oct 14, 2013, 10:20 PM
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Originally Posted by FPVSlacker View Post
Range should not be affected.

Edit: Are you asking if the change in frequency will affect your RC range or will the video TX affect your RC receiver less? The change in frequency alone should not affect your RC range, it will only help with your RC transmitter affecting your video receiver on 1280MHz. If your Vtx is affecting your RC range, changing the frequency will not help that. These are two separate issues.
Hi, so, if my video transmitter is affecting the range? Then what?
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Old Oct 15, 2013, 10:56 AM
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Hi, so, if my video transmitter is affecting the range? Then what?
1. LC filter on the power wires to the VTX (placed near the VTX) to filter noise coming out of the VTX back into your system through the wires.

2. Separate interfering components as much as possible.

3. Get a low pass filter or bandpass filter for your RC RX or buy one that has integrated filter.
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Old Oct 15, 2013, 11:09 AM
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Originally Posted by FPVSlacker View Post
1. LC filter on the power wires to the VTX (placed near the VTX) to filter noise coming out of the VTX back into your system through the wires.

2. Separate interfering components as much as possible.

3. Get a low pass filter or bandpass filter for your RC RX or buy one that has integrated filter.
Thanks! I already did 1 and 2 with no success... maybe the low pass filter will do it... do you know of one that you use and works? Thanks!
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