sudden dive

[XPS]

We saw the document. Comparing solely output power is only part of the equation when determining the overall range of an RF system.

You need to do some research about how power equates to distance. As stated, every 6dB of power doubles the effective range. If you have transmitter that has 100mW output (20dBm), to double the range that transmitter would need to output 400mW (26dBm). The same holds true for receiver sensitivity, with every 6dB of sensitivity increase also doubling the effective range.

High output power burns battery power and can actually damage your body if too high. It's also more prone to reflectivity off nearby object which can cause multi-pathing issues.

The DivBee™ RF module that we created is the longest range 2.4GHz device in existence. From RFU to RFU we get up to 7 miles of range with this device, due to the dual diversity antennas with very high signal gain.

[erhard52]

We saw the document.  Comparing solely output power is only part of the equation when determining the overall range of an RF system.

You need to do some research about how power equates to distance.  As stated, every 6dB of power doubles the effective range.  If you have transmitter that has 100mW output (20dBm), to double the range that transmitter would need to output 400mW (26dBm).  The same holds true for receiver sensitivity, with every 6dB of sensitivity increase also doubling the effective range.

High output power burns battery power and can actually damage your body if too high.  It's also more prone to reflectivity off nearby object which can cause multi-pathing issues.

The DivBee™ RF module that we created is the longest range 2.4GHz device in existence.  From RFU to RFU we get up to 7 miles of range with this device, due to the dual diversity antennas with very high signal gain.

look i have no doubt that your XPW system was good and i used it for over 10 years and was very happy and also said that you disappeared. just my latest mishap with the nano made me look into that output power , also because i had this tinySA sitting int he drawer. so none of the transmitters per my tinySA transmits the power as expected. i added the dx6i direct measurement to the doc and also this is only at 100 mW (vs expected 200mW). so it could well be my measurement. i have ordered a RF power adapter based on the https://www.amazon.com/dp/B07RR86PFC?ref...asin_title
which may work better or not - just curious.
sure the actual range is a different story but this should not prevent me from being able to actually measure the output power correctly.

oh, i also seem to remember that the elevation of transmitter and receiver has a big impact too ( fresnel zone)  on the range so from that side airplane in the sky should be much better than near ground

[flyingw]

Erhard,

When you get that XDP device, you can also use it to run the XPS "RSSI" application that comes with the suite of XDP programs.  The RSSI application displays in real time the signal strength received by the XDP device.  I performed the following experiment to compare the output of one my transmitters when I had a concern about its output.

Connect the XDP device to a PC and activate the XPS “RSSI” application.

   

Then put the transmitter module into binding mode.  Then click the button on the RSSI application and follow the instructions provided by the application.  After it connects to the transmitter, the RSSI application displays the number of channels, the frame rate, the channel hopping mode and the RSSI as received from the transmitter.

   

Be careful to keep the transmitters and their antennas and the XDP device in the same locations during the testing.

Measured on the bench, my Futaba 9C, Taranis and Jumper T12 transmitters and their respective XPS Futaba and XPS JR-type modules all delivered -36dB to the RSSI application as the strongest signal.  When I moved the transmitters to the next room behind one wall and the refrigerator, the RSSI decreased to -57dB for all three.  When I put them inside the refrigerator (a steel box), the RSSI decreased to -77dB for all three.

Since all three transmitters gave similar results, I reckoned that all three transmitter modules were transmitting as designed. If you see a significant difference with your equipment, then you may have found something.

Out of curiosity I pressed the low-power button (range test) on the transmitter modules and observed that the signal strength went down by about 25 dB.

Paul

[XPS]

When pressing the PROG button on the transmitter module (or putting it into RANGE TEST mode for the EVO), the output power drops to 0.019mW. 100mw->0.19mW = ~41.2 times the difference in range and we see this in practical applications. If your range test is good to 125 feet then your effective range will be 1 mile (on the ground).

Yes, there is a dramatic difference between the earth and the sky. Range testing directly on the ground (which is not how you are suppose to range test the XtremeLink system) is much shorter than 1 foot off of the ground. Range test over wet ground (especially grass) will be dramatically shorter compared to dry soil, concrete, or asphalt.

In our RFU testing we used a 6 foot tower at one end and a 150 foot tower at the other end and we had 90% packet success at 7 miles, at 250Kbps. Reducing the data rate increases the range and the packet success. You can safely fly on >25% packet success.

[erhard52]

Erhard,

When you get that XDP device, you can also use it to run the XPS "RSSI" application that comes with the suite of XDP programs.  The RSSI application displays in real time the signal strength received by the XDP device.  I performed the following experiment to compare the output of one my transmitters when I had a concern about its output.

Connect the XDP device to a PC and activate the XPS “RSSI” application.



Then put the transmitter module into binding mode.  Then click the button on the RSSI application and follow the instructions provided by the application.  After it connects to the transmitter, the RSSI application displays the number of channels, the frame rate, the channel hopping mode and the RSSI as received from the transmitter.



Be careful to keep the transmitters and their antennas and the XDP device in the same locations during the testing.

Measured on the bench, my Futaba 9C, Taranis and Jumper T12 transmitters and their respective XPS Futaba and XPS JR-type modules all delivered -36dB to the RSSI application as the strongest signal.  When I moved the transmitters to the next room behind one wall and the refrigerator, the RSSI decreased to -57dB for all three.  When I put them inside the refrigerator (a steel box), the RSSI decreased to -77dB for all three.

Since all three transmitters gave similar results, I reckoned that all three transmitter modules were transmitting as designed.  If you see a significant difference with your equipment, then you may have found something.

Out of curiosity I pressed the low-power button (range test) on the transmitter modules and observed that the signal strength went down by about 25 dB.

Paul

Paul thanks so much for the  tip. i will follow your advice - XDP should arrive early next week. i will keep you posted. if you have any hint on how to better use the tinySA for the purpose i would also be curious. so far the highest output i see is in the DSM2 module which does only use 2 frequencies. i wonder if the RBW on the SA impacts my measurement?
btw.: i assume all your dB are dBm right?
here again my link
https://1drv.ms/w/c/9dc6d60a8cb4c333/EYo...Q?e=axodOF.

it was funny that after i did my direct power measurement on the DX6i, when i i went back to flying i realized the connection took longer and the motion on the rudders had a bout 1 sec delay. so turned off/on did range test and all looked normal but when i flew i also had a drop out. luckily landed in high grass. - today all was normal during flying. weird.
once i am confident with the XCPS system i will use my evo12/XPS again and probably RFU instead of NANO

[flyingw]

Erhard,

When you get that XDP device, you can also use it to run the XPS "RSSI" application that comes with the suite of XDP programs.  The RSSI application displays in real time the signal strength received by the XDP device.  I performed the following experiment to compare the output of one my transmitters when I had a concern about its output.

Connect the XDP device to a PC and activate the XPS “RSSI” application.



Then put the transmitter module into binding mode.  Then click the button on the RSSI application and follow the instructions provided by the application.  After it connects to the transmitter, the RSSI application displays the number of channels, the frame rate, the channel hopping mode and the RSSI as received from the transmitter.



Be careful to keep the transmitters and their antennas and the XDP device in the same locations during the testing.

Measured on the bench, my Futaba 9C, Taranis and Jumper T12 transmitters and their respective XPS Futaba and XPS JR-type modules all delivered -36dB to the RSSI application as the strongest signal.  When I moved the transmitters to the next room behind one wall and the refrigerator, the RSSI decreased to -57dB for all three.  When I put them inside the refrigerator (a steel box), the RSSI decreased to -77dB for all three.

Since all three transmitters gave similar results, I reckoned that all three transmitter modules were transmitting as designed.  If you see a significant difference with your equipment, then you may have found something.

Out of curiosity I pressed the low-power button (range test) on the transmitter modules and observed that the signal strength went down by about 25 dB.

Paul

Paul thanks so much for the  tip. i will follow your advice - XDP should arrive early next week. i will keep you posted. if you have any hint on how to better use the tinySA for the purpose i would also be curious. so far the highest output i see is in the DSM2 module which does only use 2 frequencies. i wonder if the RBW on the SA impacts my measurement?
btw.: i assume all your dB are dBm right?
here again my link
https://1drv.ms/w/c/9dc6d60a8cb4c333/EYo...Q?e=axodOF.

it was funny that after i did my direct power measurement on the DX6i, when i i went back to flying i realized the connection took longer and the motion on the rudders had a bout 1 sec delay. so turned off/on did range test and all looked normal but when i flew i also had a drop out. luckily landed in high grass. - today all was normal during flying. weird.
once i am confident with the XCPS system i will use my evo12/XPS again and probably RFU instead of NANO

I am unable to comment on the Tiny SA measurements as I have no experience with that device.  In fact, the I used the RSSI measurements from the XDP only to compare several radios - I didn't know what the actual RF power output values were.

Yes, dBm.  Also, I believe that the DX6i's label of 17.93 dBm on the RF board is accurate.  Add the gain from the antenna and it's very close to the legal 20 dBm limit.

Your observation of slow-responding controls is mysterious, but it doesn't sound like an RF problem.  Power maybe?  Or someone is jamming the 2.4GHz band at your flying site?

[erhard52]

Erhard,

When you get that XDP device, you can also use it to run the XPS "RSSI" application that comes with the suite of XDP programs.  The RSSI application displays in real time the signal strength received by the XDP device.  I performed the following experiment to compare the output of one my transmitters when I had a concern about its output.

Connect the XDP device to a PC and activate the XPS “RSSI” application.



Then put the transmitter module into binding mode.  Then click the button on the RSSI application and follow the instructions provided by the application.  After it connects to the transmitter, the RSSI application displays the number of channels, the frame rate, the channel hopping mode and the RSSI as received from the transmitter.



Be careful to keep the transmitters and their antennas and the XDP device in the same locations during the testing.

Measured on the bench, my Futaba 9C, Taranis and Jumper T12 transmitters and their respective XPS Futaba and XPS JR-type modules all delivered -36dB to the RSSI application as the strongest signal.  When I moved the transmitters to the next room behind one wall and the refrigerator, the RSSI decreased to -57dB for all three.  When I put them inside the refrigerator (a steel box), the RSSI decreased to -77dB for all three.

Since all three transmitters gave similar results, I reckoned that all three transmitter modules were transmitting as designed.  If you see a significant difference with your equipment, then you may have found something.

Out of curiosity I pressed the low-power button (range test) on the transmitter modules and observed that the signal strength went down by about 25 dB.

Paul

Paul thanks so much for the  tip. i will follow your advice - XDP should arrive early next week. i will keep you posted. if you have any hint on how to better use the tinySA for the purpose i would also be curious. so far the highest output i see is in the DSM2 module which does only use 2 frequencies. i wonder if the RBW on the SA impacts my measurement?
btw.: i assume all your dB are dBm right?
here again my link
https://1drv.ms/w/c/9dc6d60a8cb4c333/EYo...Q?e=axodOF.

it was funny that after i did my direct power measurement on the DX6i, when i i went back to flying i realized the connection took longer and the motion on the rudders had a bout 1 sec delay. so turned off/on did range test and all looked normal but when i flew i also had a drop out. luckily landed in high grass. - today all was normal during flying. weird.
once i am confident with the XCPS system i will use my evo12/XPS again and probably RFU instead of NANO

I am unable to comment on the Tiny SA measurements as I have no experience with that device.  In fact, the I used the RSSI measurements from the XDP only to compare several radios - I didn't know what the actual RF power output values were.

Yes, dBm.  Also, I believe that the DX6i's label of 17.93 dBm on the RF board is accurate.  Add the gain from the antenna and it's very close to the legal 20 dBm limit.

Your observation of slow-responding controls is mysterious, but it doesn't sound like an RF problem.  Power maybe?  Or someone is jamming the 2.4GHz band at your flying site?

regarding output  power i assumed that it is the total rf power emitted without antenna gain but who knows. 
on the interference you are right , i had the same thought about strong interference or almost as you state like broadband jamming. it was moving like in slow motion. or i was in a time warp somehow.
strange to have to deal with these things. i thought that problem was left behind 40 years ago before FHSS

[XPS]

Slow controls can be interference, like every n'th packet is getting through successfully. With the Spektrum system you can deliberately cause this if you blank out the upper or lower frequency that it uses - the Spektrum uses 2 frequencies, randomly selected 1 in the lower 2.4GHz range and 1 in the upper 2.4GHz range. You can blank out a frequency easily with a video transmitter. With two video transmitters you can stop the Spektrum system completely.

[erhard52]

Slow controls can be interference, like every n'th packet is getting through successfully.  With the Spektrum system you can deliberately cause this if you blank out the upper or lower frequency that it uses - the Spektrum uses 2 frequencies, randomly selected 1 in the lower 2.4GHz range and 1 in the upper 2.4GHz range.  You can blank out a frequency easily with a video transmitter.  With two video transmitters you can stop the Spektrum system completely.

thanks Paul
oh i did not know - so a video transmitter could be like a drone transmitting live stream back?
so that would make DSM2 fairly vulnerable
erhard

i do have DJI drone so i could check when they are active with the tinySA on what frequencies they work

[XPS]

If the drone is using 2.4GHz for it's video, then yes. DJI uses 5.8GHz for it's video, but there are 2.4GHz systems in use - including repeaters. NexRAD uses 2.7GHz at 500KW of power, which bleeds into the 2.4GHz band too.