How to tune up the frequency on video tx and rx

[kaos]

Thomas: I will try the 'far away' 1st, then the capacitor.

Kilrah: care to share your tiny DC/DC boost convertor. that sounds like the best way to ensure the cam and vTx with sufficient voltage powered by 1S while adding filter effect.

[Kilrah]

Hope your hands are precise (the ruler is in cm of course)

[thomas9x]

Hope your hands are precise (the ruler is in cm of course)

Tiny! Don't drop it on the shag carpet.

[Kilrah]

I definitely have lost a few components that decided to fly off the tweezers since I started making them...

[kaos]

That looks like Iron man's head hit by a brick.
A 5V reg with caps?
I do like to know how to make this thing.
I tested the system with model power, it definitley has 'a lot' of effect on the image. once motor start turning, it is like looking through a louvered window.
with separate lipo, there is still some negligible effect when higher throttle is applied.
my 138 mah lipo is 3.6g, 150mah lipo is 5 g. The only cap I have to try ''filter' is a 3300 uF 16V cap which weighs 9+ g.

I was getting signal weak/loss at 45 yards, but this is a static test, the quad is sitting on the concrete drive way. the tx/ant is on the belly only 1 inch above ground, so it may not be a good test for range. it is just too windy and hot here to test fly this today. Especially i still have trouble with the stock V212 tx control. (v212 is the new v949, and don't buy it unless you are relying on the self leveling to fly a quad. It is not good/smooth at all, compared to the v959 stock tx. especially when using T9x the v959 is much better/smoother to fly). I will probably put this on the v959 than v212.

Now I have a micro vTx that can work, it is time to tackle my 808 #16 v2 to use with this vTx, so I can record HD video while flying FPV with v959.
Time to make a 2nd tx with this module using whip antenna to be used for Q-bot mciro. and see how the whip antenna compare to the clover leaf. Don't need a lot of range for Q-bot micro as long as the image is stable.


edit: I am supposed to have my 20X over head loupe with lighting this wk, but Banggood just told me (after complaining it is not here) they 'think' it is lost in the mail. willing to ship the whole order again. that means I have to wait another 21 days to hit the iron man with a brick.

[kaos]

Tiny! Don't drop it on the shag carpet.

I will use a piece of roach/rat trap paper on the floor when doing it.

[kaos]

Kilrah:
can you list your DC/DC converter parts and schematics? while I am waiting for the 20X loupe, I can gather these parts. Thx.
I think that DC/DC converter is the best solution for micros.
for the Q-bot micro/x4, extra 1S lipo is just too much to handle. I measured all the weight for vTx together, and put the weight on my Q-bot micro, it is 'heavy' and the fly time time is down to 5 min without additional lipo. I probably can use a 70 mah 1S to reduce weight, but that won't last enough time for FPV through the whole flight.

[Kilrah]

I use an LTC3200-5 with 3 2.2uF 0603 size ceramic caps arranged as per the reference design in the datasheet.

[kaos]

Thx Kilrah. sort of knows where to solder the 2.2uF caps. When I get them in my hand I may double check with you again.
You mentioned due to the high current draw of your vTX you used 2 of these, one for cam, one for vTx. What vTX you use? (20mW)? what current draw on your vTX?
This one I have from Thomas is a 10mW, the only current info I have is typ: 170mA max: 180mA. Is that considered high?
I looked at the LTC3200-5 data sheet, it seems like it only handles up to 150 mA?
and you are using the S6 packaging right?
Will these work:
http://www.digikey.com/product-detail/e ... ND/1754254
between the following two caps, which works better?
http://www.digikey.com/product-detail/e ... ND/3954908
http://www.digikey.com/product-detail/e ... ND/2733516

Thomas: Made another tx from the 2nd module which has the Ant/GNd tested as 'open' and used a tiny whip antenna I have. wala, good video showed up. I tried a PlanarSkew Rx antenna and a stick rx ant, seems with a PlanarSKew rx antenna does get a little better reception. only walked up to 15 yards outside the house. Works like a charm. Don't know for sure the range either till I can truely test it in the field. but in the house and 15 yards out in the yard (with vTx in my bricked house), it looks good. Looks like the ant/gnd tested either 'open' or 'closed' with ohmeter does not make any difference. Still interesting why one would test 'open' while the other 2 test 'closed'

Did a little FPV test fly with my V212. Geesh, with this 90 degree lens trying to hover in a 5x6 space, especially with stock Tx, is difficult. no depth reception- like looking at a view with one eye closed, by the time I was aware of I am close to the edge it is a little late. I guess now I know why Kilrah put a 120 degree HD lens on his.
but I will get used to it.

[thomas9x]

I tried a PlanarSkew Rx antenna and a stick rx ant, seems with a PlanarSKew rx antenna does get a little better reception.

The preferred 5.8GHz antenna solution for common FPV flying environments is circular polarized designs (Skew Planar Wheel is popular) on both the vTx AND vRx. The reason is that when both ends are circular polarized (used in pairs) they will substantially reduce multipath interference, which is a nuisance for FPV.

But with your small aircraft you will need to use a simple wire monopole (linear polarized antenna) on the vTx due to weight limitations. In that case a good performing linear patch antenna on the vRx would be a reasonable choice. But if you can achieve the desired range with your Skew Planar or whip (stick) then go with them. RF success is all about experimentation and choosing what works best for YOUR installation, operating environment, and convenience.

Still interesting why one would test 'open' while the other 2 test 'closed'

The explanation for why your ohmmeter shows a short is because of the inductor in the band pass filter that is inline with the RF power amp's output circuit (which is where you are measuring with your ohmmeter). It is SMD dielectric ceramic filter that has an architecture that is similar to the drawing below. This filter is not used in every RF module but is common for the stuff that may end up in consumer products (because of the strict RF rules for such goods).

To determine why the one module is not "shorted" would require dis-assembly and close inspection of module's internal PCB at the antenna port. But if it has similar range to the other modules then leaving it alone would be the best thing to do. But if you must know why it is not the same as the other two modules then it will most likely require a module tear-down.

- Thomas

[kaos]

Thomas: Thx for the explanation. (as if I really understand it fully but conceptually yes. )
I think I am going to leave it alone than tear it down. Since I have 3 modules, once I have all 3 working, I will do a real comparison to see if there is a difference in range. I put the one with stick ant on my q-bot micro today and add an extra 138mah lipo to power the cam and vTx. It surely feels heavy for the Q-bot micro, 75% throttle to keep it in the air, but it is successful. The fly time of original q-bot micro is about 9-10 min, but I added two led on it and it was reduced to ~ 8 min. With the additional Franken set up was able to fly 3:47. It is a Franken make-shift with tapes to fix them on q-bot now. I will get another q-bot micro without adding on leds and hard wire everything under the hood to streamline/get rid of all the connectors. that should shave off a couple grams. then with Kilrah's DC/DC converter while using a bigger lipo to power the whole thing. I measured the weight of a 300 mah lipo and the weight of the 240mah for Q-bot micro + the 138 mah(which gives more than 6 min of operation for vTx/cam) will again shave off 3 more gram. that should give me around 6 mine fly time. I just hope q-bot still can flip with the streamlined weight. With the current Franken set up, I doubt it can.
I am uploading a short vid that was recorded through the RC305 with a stick Ant (forgot to put the 4 leaves on ) with a basic DVR. in my goggle using a 4 leaves ant, it looks better. I think it is the DVR is not so good reducing the quality of image. The actual monitor/goggle image seems better.

here is the vid: the blue flashing hue is from my super bright flashing led at front of the Q-bot micro. The lighting obviously contribute to some fuzziness as well, all at night with house light.
http://www.youtube.com/watch?v=8Gxs0hX- ... e=youtu.be

[thomas9x]

The video looks good. Your antenna choice seems to be doing fine in this environment.

- Thomas

[kaos]

good to know it is doing the right thing. I really don't know how good or how bad an image to expect for this module.
time to order the DC/DC converter parts and new Q-bot micro.

Do you know a place to get the 20-50 mW module for the RC305/Boscam system without buying 2 dozen at a time? I think a 20-50mW module will be able to do most of my planes for FPV as far as range is concerned.
I am planning on all my planes will be FPV ready. I have this 808 #16 V2 with 120 degree lens, planning on taking it apart and rigging it up for my planes (most of them are 80cm in size) with pan and tilt like a drop in module so I can put it on the plane any time. a 20-50 mW should be able to reach 500M-800M which is plenty for these 8-12 min flying planes.

[thomas9x]

Do you know a place to get the 20-50 mW module for the RC305/Boscam system without buying 2 dozen at a time?

The TX5813 5.8GHz modules you have are the same as the "20mW" advertised by others. I have a few more to offer, but you can find them from FPV retailers like foxtechfpv.com.

The only other choice I know of is the "200mW" RF module (TX5823). For example:
http://www.foxtechfpv.com/tx5823-200mw- ... p-272.html

BTW, I've been told the TX5823 is actually about 50mW but I have not personally confirmed that. If this is true then I suspect you will achieve about 1.5x more range with the TX5823 versus your existing TX5813 modules. But if the TX5823's RF power is ~200mW then range would be increased to almost 4x.

- Thomas

[kaos]

interesting. the 200mW module I have from RCtimer that does not work with rc305 is recommended to have a heat sink to go along with it. and it is burning hot while operating when I tried.
in the Foxtechfpv site their pics actually using no heat sink. if it runs as hot as mine, I think it will melt my foam plane.

I do have a 200mW Tx as a set with RC305 from HK. but it is quite heavy and runs on 3S. this TX5823 runs on 3.3 V and light weight, would be good for smaller plane while has longer range. I will give it a try. Thx for the info. I had looked some sites and Foxtechfpv site, just don't know which one actually works with RC305. (That is why I got mine from RCtimer which is a US vender but won't work with my system )

Now I start to see the end of tunnel for my FPV system(s) set up. thx for all the help.

This afternoon I made another tiny whip antenna out of the coaxial cable left behind from my working on clover leaf ant, ready to go on the 3rd module.
Because the one I tested works very well with my system, I just measured the antenna length out of it and it is 16.64mm on exposed core part and use that measurement.
I also did another test fly with a 70 mah lipo powering the vTx, it actually lasted the whole fly ~4 min and still has 3.82V left. This TX5613 really does not burn that much amp at all. That saved anther 1.5 gram from the 138mah lipo. Through out the fly, although it was only about 10-20 ft from me, there was not one single interferences of any kind. Can't wait to get out in the field to see how well it performs at distance.

[kaos]

well, finished my 1st complete fpv fly wiht goggle with my v212. Really need to get used to this 'narrowed vision'. Hard to tell the height and distance to sruurondings. Looks like with this 10/20 mW vtx the range stops around 50 yards. But this is with my DIY ugly 3 leaf ant mounted under the belly.
1st batt end up going up 200 ft (from my friend who is looking for me) and end up coming down 50 ft behind me. But on the 2nd battery, start to manage to fly around in front of my doing figure 8s. But still come down a few times thought I was still in the air but already touched the ground. Need to get used to looking through the goggle and judge the height better. Due to the light weight of v212 it is easy to go up 100ft befroe I know it when the air is uprising.

was going to change to the other vTx with whip ant , but the heat/humidity got me. will try next time with the HK 3 leaf ant to see if it does better.
when the video goes out, it goes out fast. I looked some fpv video, it seems in the beginning it usually start to flash before it goes out. Mine seems to flash a couple times and goes out completely. the video pict is petty clear through out until the video drops after a couple flashes. Does that sound normal?

I think I finally found a good character for v212 is the self stabilization. It does keep a float if you release both sticks and stay in the air on its own.

Kilrah:
what is your trick of keeping the perception of height and distance? Not too many people can fly a UMX sbach wiht goggle while take off and land right at your feet as you did.

[thomas9x]

Code: Select all

when the video goes out, it goes out fast. I looked some fpv video, it seems in the beginning it usually start to flash before it goes out. Mine seems to flash a couple times and goes out completely. the video pict is petty clear through out until the video drops after a couple flashes. Does that sound normal? 

Clear video that suddenly drops out while flying around is a symptom of multipath interference. Operating in wide open areas, away from ALL structures (cars, fences, buildings, etc.) will usually help reduce the dropouts. Along with doing that, the modern 5.8GHz solution is to use circular polarized antennas on the vTx *and* vRx. If you are doing all these things, and are sure your circular polarized antennas are correctly tuned, then diagnosing the problem might possible by posting a flight video for us to look at.

But this is with my DIY ugly 3 leaf ant mounted under the belly.

Yes, be sure your vTx antenna is in a location *below* the aircraft (the vTx's antenna should be pointing straight down). The vTx antenna must have direct view of the vRx's antenna; Orientations where the model is between the two antennas will cause a signal fade, which can cause temporary video loss. So placing the antenna under the model helps to reduce the chance of the model blocking the RF signal as you fly around.

will try next time with the HK 3 leaf ant to see if it does better.

From the reports I've heard, the HK (and other Chinese made) "Cloverleaf" and Skew Planar Wheels are poorly tuned and have MUCH shorter range than the correctly made (optimized) antennas. But they may work better than a DiY version, so worth a try.

- Thomas

[kaos]

I will make a video next time. Today I was just trying it out. no time (nervousness/excitement ) to hook up the DVR.

yes, the DIY is under the belly but is pointing forward horizontally (no particular reason just the easiness of mounting), I will try to mount it pointing straight down next time. (it is 101F out there now without heat index)
NOw think about it, I do have a sma male/female converter on the rx side (did not pay attention to the male/female thing when ordered HK ant), would that drop that much distance? from ~300 M to `50 yard?

As for the HK ant. hmm, we will see when I use them as a pair.

when you say antenna tuning, would you elaborate a little? the DIY 3 leaf I have is just based on the IB crazy's formula. but my soldering technique with the welding wire may be way off. I will try to make another pair to see if it works better. or there is other 'tuning' technique?

[thomas9x]

the DIY is under the belly but is pointing forward horizontally (no particular reason just the easiness of mounting), I will try to mount it pointing straight down next time.

That is the wrong orientation for FPV applications. Point it down or point it up, never horizontal.

NOw think about it, I do have a sma male/female converter on the rx side (did not pay attention to the male/female thing when ordered HK ant), would that drop that much distance? from ~300 M to `50 yard?

The 5.8GHz RF loss from the adapter will depend on the quality of the adapter's materials, which is not at all related to how good it looks. Basically, if you have to use an adapter then there's not much you can do, but where possible it is best avoid them.

when you say antenna tuning, would you elaborate a little?

Even if you do your best to follow the online guides, DiY 5.8GHz antenna builds will probably result in a antenna that is not optimized. Measuring the antenna's VSWR is the only way to know if it is correctly made. I think ibcrazy posted a DiY SWR meter over at rcgroups. So check over there to see what the serious antenna builders are doing to measure their masterpieces.

FWIW, I see a lot of DiY 5.8GHz antennas made with RG316 coax. Even some commercially made 5.8GHz antennas are using it. That inexpensive coax is fine for 900MHz-2.4GHz designs, but my opinion is that the high RF losses at 5.8GHz make it a poor choice. Instead, consider using lower loss semi-rigid coax such as RG402 on the 5.8GHz builds.

it is 101F out there now without heat index

My backyard thermometer is reporting 108F in the shade at the moment. But it's a dry heat.

- Thomas

[kaos]

thx Thomas.
yep, my extra coax with sma cable is R316. But since I already have it, i will try it any way. if still not good then RG402 is on the menu.
I will check the VSWR thing. if not too hard/expensive to make, may be I should build one.
No wonder IB Crazy can reach 15-20KM with his polarized /spiral antenna. 'little' details I missed.

edit:
I think I may have found the reason the signal lost at 50 yards. Just reading about these VSWR. it darned on me, I made these DIY ant at the same time and made them the same direction (it turned out to be right hand polarized, I just found out) But I ordered the HK ant without even thinking the direction and I just found out the HK is right hand too. (pure luck ) so I was just checking on my DIY ant, found it is right hand BUT one of the leaf is knocked loose at the center I did not even notice it. It could be knocked out during the 1st crash, or yesterday in the kitchen. If true, it is already super I got clear video at < 50 yard
I will resolder it and try next time going to the field.

[Kilrah]

Kilrah:
what is your trick of keeping the perception of height and distance? Not too many people can fly a UMX sbach wiht goggle while take off and land right at your feet as you did.

10 years of FPV and a good feeling

Nah it should come quickly enough, although I wouldn't say a quad or heli is the best thing to start. Also, for exemple on the video you psoted earlier the camera looks too high. You need to always see the ground when flat and when tilting backwards a bit.

[kaos]

I have been into FPV for 30 yrs. Fussing with Pay per View.

yes, that cam was mounted at the top of the Q-bot. So you are saying mount it in a way when you are flying level, you see more ground than the air up high? I know in the house, once it is lifted I see no ground just cabinets and wall. The only time I will see ground again most of the time the image is up side down.
I will give that a try. this 90 degree lens does make me feel like looking through a small tube with one eye and try to fly.
does 120, 140 or 170 degree lens help or worse?

[kaos]

get 4 more practice fly on the goggle in the house, I think I can manage to fly from one room to another now. I figure if I practice 3 fly /day, after 3 months I should be able to start flying FPV in the field for real.

Here is the question: if I make the DC/DC converter as Kilrah designed, one for cam, one for vTx, I should be able to eliminate both 470 uF capacitor on the vTx right? or I still need to keep the cap on the video line from cam to vTx?

[thomas9x]

I should be able to eliminate both 470 uF capacitor on the vTx right? or I still need to keep the cap on the video line from cam to vTx?

Both those caps are factory recommendations, regardless of how you are powering the module. If you need something smaller then consider using 470uF 6V rated SMD tantalum caps.

I doubt they would be much smaller, but 330uF 6V would be a second choice. Lower uF values are not recommended but may work out if you have no choice in order to meet your weight goals. For example, it may still work fine with a 100uF V+ cap and a 220uF video sig cap. Electrical designs often require compromises, so you will have to choose between performance/reliability vs. practicality.

- Thomas

[kaos]

OK, so the Kilrah converter is just to eliminate the noise from the single battery usage, but caps are still needed for this module to operate properly.

[kaos]

found this one 6.3V smd 470 uF 7343 is smaller a little, it is flat, may be a little eaier to fix/mount for micros. the one i have now is about 12x7 mm
http://www.ebay.com/itm/5x-Tantalum-Cap ... 1c33b5cf0e

This should work??

[thomas9x]

The cap's description is fine. But I don't recommend using tantalums from China suppliers. Too many are fakes and/or mislabeled misfit parts that have short lives (and spectacular endings). Places like Mouser and Digi-Key are safe suppliers (but of course more expensive than eBay).

- Thomas

[kaos]

Thx Thomas. Yes, found the 6.3 V 470 uF 7343 caop at Digikey, 3.63 a piece, only the micro need this, might as well get them from reliable source, only need two.


Kilrah:
I am going to order these parts from Digikey with the above caps:
http://www.digikey.com/product-detail/e ... ND/1754254
http://www.digikey.com/product-detail/e ... ND/3954908

Just want to make sure these will work. I read the data sheet the LTC3200-5 is rated for 100mA and absolute max is 150 mA. I think my 20mW VTx (TX5813) is rated at 170-180 mA, while the 200mW(TX5823) is rated at 340-350 mA. would they work together? or I need to use something else?
you mentioned you use one for the cam and one for the vTx. the cam is OK , but the vTx even the 20mW is exceeding the LTC3200-5 rating.
Please advise.

[Kilrah]

The LTC3200 is definitely operating out of spec with the 20mW, so it's in theory a hit or miss situation. I tried and it worked for me, so I was happy and it has ran for numerous hours now. Your mileage may of course vary. No chance with 200mW.

I never fit the caps recommended by the module datasheet. After much testing with the voltage regulators I use I could never notice a difference with or without.

[kaos]

haha, Kilrah I did not know you are a person that walks on thin ice too.

knowing that, I will try your way without the caps too. use one DC/DC converter for cam and one for 20mW vtx. weight/space is premium on micros.

another reason I want to try without the caps is when I look at the Foxtechfpv site's 200mW Tx (TX5283) sample pic, they don't use caps either. although in the manual they provide it also have the 470uF cap in there. They probably have tried without the 470cap too.

Have you thought about using a different LTC with higher voltage rating/current draw to use with higher power Tx? It would be convenient to be able to use the same power source for larger model too. I have a 2g cam using 3S, but if a DC/DC converter can get rid of the video noise, that would be great to use the same 3S power pack for vtx/cam and the plane without a separate power pack. Now while on the larger fpv setup, if I use a say 5V BEC for cam and vTx, will that works as a 'filter' too when using the same power pack for the motor? if that is the case I can jus add a ext BEC from power pack to cam/vTx. that would be great.