127 replies to this topic

[Mr.RC-Cam]

After hounding Airwave for a couple years, they finally released a 5.8GHz/500mW transmitter module late last winter. It is part number AWM667TX, shown here: Click me! It has very good image clarity (better than most) and I have confirmed that RF power is really 500mW, so it is a nice product.

This RF module requires additional components, so a prototype board was created for it. But other than bench testing, I haven't had any time to perform FPV field testing. Long time forum member Terry (UK) has one too (he is an avid 5.8GHz user). But his schedule/weather has not been cooperative, so testing continues to go slowly.

To move things along, I have a proposal. I'll put together a 5.8GHz 500mW Tx/Rx package (with antennas) and price it low as I can. My target is $149 USD (+ shipping). The special deal would be extended only to registered rc-cam forum members. This is much like the RSSI meter deal that was recently promoted here.

Here are some things that may help you decide if 5.8GHz is worth your efforts to try out:

1. 5.8GHz is not for long range FPV. The 500mW system is for those that won't venture past 2000 meters or so. I believe that Terry has flown past 1500 meters with his lower power (100mW) 5.8GHz Tx with custom diversity base station.

2. If you do not currently use 900MHz - 2.4GHz wireless video, then do not consider using 5.8GHz yet. 5.8GHz is targeted for those that cannot use the more popular frequencies.

3. Multipathing interference is more prominent at 5.8GHz. To minimize this problem 5.8GHz should avoid areas that have nearby structures (buildings, fences, etc.).

4. 5.8GHz is ideal for those that have tried 900MHz-2.4GHz and have unresolved external interference issue due to nearby RF sources (cell towers, WiFi, etc.). It is also a valid choice for those countries that do not allow legal amateur radio use on the other frequencies.

5. 5.8GHz can be used with 2.4GHz R/C systems. But I say this with reservations since my experience is based on the earlier 100mW Tx. Hence, more testing is needed.

The next couple posts will show the project photos so that you can see what is involved.

Edit: Package deal information posted here: http://www.rc-cam.co...dpost__p__24850

Edited by Mr.RC-Cam, 20 June 2010 - 12:11 PM.
Added link.

[Mr.RC-Cam]

Here is what I had in mind: (1) An assembled 500mW Tx with SMA-RP connector (2) Tx dipole ducky antenna (3) 5.8GHz Rx with integrated (hard wired) patch antenna.

The Rx is uses Airwave's AWM682RX RF module (which has RSSI) and is unique in that the integrated patch antenna has a preamp (LNA) built into it. The entire Rx/Patch unit is small enough to fit on the popular Antenna Pan/Tilt mechanisms that are being sold by the FPV shops. Full details to this Rx are found here: Click Me!



 
As an alternative, a Rx without the integrated antenna is available. It has a standard SMA antenna connector. This Rx is based on Airwave's AWM660RX module, which does NOT have RSSI. Full details to this Rx are found here: Click Me!



 
If you need RSSI then I recommend the Rx with the integrated patch. If you want to use another antenna with it then I suppose you could hack-in a SMA connector. However, keep in mind that the integrated patch antenna works well and changing it is might not be worth the effort. Regardless, be sure to state which Rx you need.

[Mr.RC-Cam]

The transmitter is a prototype configuration. It's a bit larger than the typical 900MHz Tx. Size is 2.5 x 1.25 x 0.5 inches. Weight is 35 grams. Ultimately it can be made smaller, but this one is what I have to offer.

The Tx will accept 6.5 - 14VDC. The onboard VReg is a buck DC-DC switcher that allows 2S and 3S lipo sources. It has two stages of LC filtering for effective noise reduction. There is also an LED power indicator to show the power supply is OK.




As shown, the Airwave transmitter has a heatsink to keep it cool. Not shown, but the DC-In power cable has a JST/BEC connector. The Audio/Video inputs are servo style cables. The Video cable has LC filtered battery voltage on it and the Mic cable has regulated 5V (to power mic preamp, if required).

[Mr.RC-Cam]

If you are interested then please post your "I want one!" Do not email or PM me: raise your hand here. If enough interest is shown I will proceed with the package deal.

Lastly, Terry has agreed to share his 5.8GHz experiences. So if you have any questions he can answer then he will chime in.

[Mr.RC-Cam]

By the way, it is compatible with iftron's 5.8GHz FPV products. If you already have their stuff then you can use these components with it. Keep in mind that their 5.8GHz 500mW Tx and matching Rx is over $400; The lower cost of this package should take some sting out of trying 5.8GHz for the first time.

[Terry]

If anyone like me now finds 2.4Ghz not usable due to wifi and is not able to use 900mhz or anything else due to it being used for other services in their country then 5.8Ghz is the only way to go. There has been a lot of talk about it not being any good due to poor range and bad multipath interference but I dont think any of those guys have tryed very hard to overcome the problems.

Yes range is a little less compared to a clear 2.4Ghz channel but I had an increase in usable range when I changed to 5.8Ghz due to me now having a wifi clear channel. If you suffer from wifi then you wont worry about a little less range. I have had a mile with a 100mW TX and a simple RX aerial I would guess is about 5dBi. With the same 100mW TX I have had over 1.5 miles with a rock solid picture using a 14dBi patch, Im sure there was plenty more range to be had but I lost my bottle. If the 500mW TX is good then I think a lot of guys will need to worry about their rc range more than the video range.

Multipath interference can be more of a problem on 5.8Ghz but if you like me fly in a big open space it wont give you any trouble. I had most of my problems flying close to houses or pylons.

The only other thing worth a word is that pointing the aerial out the bottom of your plane is IMO the only way. The short wavelength of 5.8Ghz seems to be blocked very easy by servos or leads or almost anything. You will get interference simular to multipath but it is not.



Terry

[Devonian]

Darn, and double darn!

I've just bought 5.8 airwave Tx & Rx modules (similar setup to Terry) to test things for myself - Rx's are on back order.

I'm going ahead with 5.8 as my brother and I often fly together in a local, suburban field and we both fly 2.4 for r/c and know there's plenty 2.4 wifi around as I've scanned around with my netbook and NetStumbler.
I'm also interested to test some ideas with circular polarised aerials, both on Tx and Rx to try to reduce/eliminate the multipath interference.
To that end, I am looking at a 'crossed Yagi' at the Rx end to give decent gain.
For me, the ultimate solution would be a fully continuously rotatable auto tracking system.
I can make the required slip ring gear mount, but the electronics and software are beyond my DIY skills.

Very tempted to say 'I want' but would ask first if it's possible to have a part system - maybe just the Tx only ?

Nigel.

[Mr.RC-Cam]

To that end, I am looking at a 'crossed Yagi' at the Rx end to give decent gain.

I think cross-Yagis are great. However, unlike the 900MHz - 2.4GHz designs, a DiY 5.8GHz version is a bit impractical without a network analyzer to help optimize the build. So, my fatherly advice is to stick with the commercially offered antennas instead.

Very tempted to say 'I want' but would ask first if it's possible to have a part system - maybe just the Tx only ?

My goal here is to provide a known setup so that the reported performance data is easier to digest. So, for now I am only interested in offering the package. However, we can revisit your request later on after the dust settles. Please note that much of the cost in this special deal is in the 500mW Tx, so the savings won't be staggering if you omit the Rx; You might as well get the nice Patch antenna equipped Rx to go with it.

[Devonian]

I like experimenting with antennas and can regularly make ones that out perform the commercial offerings.

I like this 'modular' aproach with Ethernet cabling at the ground station
http://www.rcgroups....d.php?t=1238311


I've decided to sell some of my DSLR camera equipment to further fund things - anyone interested in a near immaculate, Canon 5D with low shutter count?

I may yet get to say 'I want one' (complete package).

Nigel.

[Terry]

I'm also interested to test some ideas with circular polarised aerials, both on Tx and Rx to try to reduce/eliminate the multipath interference.

The problem is making the yagi will be hard enough but making a circular polarised omni aerial for the TX will be ever harder. Both will be needed to reduce multipath, just using a circular RX aerial may even make it worse.
My 14dBi patch seems to be quite good at ignoring mutipath and is a much easier way to go. Dont let me stop you doing it though, I would love a circular polarised system

Terry

[Devonian]

Ebay has been good to me today, I'm in "I want one".

Preference is the 'simpler' Rx as I see it as more flexible for antenna connectivity.

Nigel.

[kist2001]

I'm in. -Ken

Ps: I would like two transmitters as I am cruel with my gear.

[Mr.RC-Cam]

More details posted here: http://www.rc-cam.co...dpost__p__24850

Score board for the I-want-one votes:

Devonian, COMBO #1, (SHIPPED JUN-21-2010).
kist2001, COMBO #1 & SPARES#1, (SHIPPED JUN-21-2010).
docphi, SPARES#2 (SHIPPED JUN-22-2010).
Cyb, Combo #1 (SHIPPED JUL-16-2010).
kc6f, Combo #2 (SHIPPED JUL-27-2010).

Note: I will update this list as more join in.

Edited by Mr.RC-Cam, 26 July 2010 - 03:08 PM.
Updated List

[Devonian]

c'mon people, hurry up and show your interest.
That ebay profit is burning a hole on my pocket

Nigel.

[Mr.RC-Cam]

c'mon people, hurry up and show your interest.

I guess we will have to show them how they missed out. I will move forward and build enough for those on the existing list; Should be available in about two weeks or so.

[Mr.RC-Cam]

Latest News:
I've update post #1 to include details to the Rx with the SMA (instead of integrated patch with LNA). The Tx's are being built by a commercial board assembly shop and they are due in about a week.

[Devonian]

Ah, I prefer to have RSSI

Is it possible just to have Tx only? (I have 2 x AWM682 Rx's anyway)

Nigel.

Edited by Devonian, 10 June 2010 - 12:41 PM.

[Mr.RC-Cam]

Is it possible just to have Tx only?

Sure, if there are any extras then I will be happy to do that. But only after I exhaust all efforts to find homes for the Tx/Rx package deal.

[Devonian]

Sounds fair to me.

As you said, the patch Rx won't make a huge difference in pricing, so I'll opt for that rather than delay things if your initial sales of a package don't go quick enough.

Nigel.

[Mr.RC-Cam]

The assembled 5.8GHz / 500mW transmitters have been delivered. I'm QC testing them now.

I'll need a couple days to create some simple instructions (just have to fit the task into an over-booked schedule). Once they are posted I will release the special deal to those on the list that want it.