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Old Apr 27, 2010, 10:28 PM
Martin - AKA mr.sneezy
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Adelaide, Australia
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Originally Posted by Fly2High View Post
Can someone measure the dimensions of the 7channel vertical pin with servos attached?

I am wondering if it will fit in a DLG pod.

Also, is there any talk of a 5 or 6 channel version (with dual antennas)?

thanks

Frank
The 8Ch receiver is quite slim already Frank, and if you remove the hard case and then just shrink wrap it with heatshrink you can get it down by another 3mm in the minor dimensions. That would make it around 20.5mm wide...

The way the two circuit boards plug together the shrink will hold it all in place nicely.
My 2 cents
Martin
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Old Apr 28, 2010, 07:19 AM
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Wuxi, China
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Originally Posted by kcaldwel View Post
Any chance there will be an end pin version of that nice new 7ch. Rx? That would make it a lot more useful for the narrow sailplane fuselages.

Thanks,

Kevin
Hi, Kevin

Actually we have this end pin version of 7ch. Rx. If having some demands, we will push it to the market later.
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Old Apr 28, 2010, 07:34 AM
Chuck 'Em and Chase 'Em
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United States, NY, Plainview
Joined Aug 2005
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My dlgs are only about 22mm - 28mm at the widest point so I would like it to be as narrow as possible.

An end pin 7 channel or even an end pin 5 or 6 would really suite the DLG guys perfectly.

The lack of 'as is' install is the only reason I haven't purchased a module myself.

I am also concerned with the height. With top pins, I may not have enough room to plug them in and slide it into the fuse (similar dimensions vertically)

Hope the end pins are soon released!!!

Frank
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Old Apr 28, 2010, 09:46 AM
"...certainty is absurd."
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Quote:
Originally Posted by jonathan-FrSky View Post
Hi, Kevin

Actually we have this end pin version of 7ch. Rx. If having some demands, we will push it to the market later.
Jonathan,

Thanks very much for the reply.

Sailplane pilots would definitely be interested in an end pin version of the 7 channel, or an even smaller 5 or 6 channel as Fly2High mentioned. I think an end-pin 7 channel would be fine, with the case removed. 7 channel end-pin in shrink wrap?!

I am very interested in your system, it looks very good.

Thanks,

Kevin
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Old Apr 28, 2010, 05:53 PM
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as far as i know, Futaba FASST is sensitive to 1,2 ghz transmitters,

any one with a FrSky kit and a 1,2 Ghz video transmitter can take some test to see how strong is to interferences?

thnk you very much
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Old Apr 28, 2010, 06:23 PM
Martin - AKA mr.sneezy
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More testing - For the tech heads here.

Adding to the range testing done last week, I've now put my V8FT transmitter module over the RF transmission analyzer, and captured a full span spectrum usage image and also done a power measurement in Channel Power mode (specially used for Spread Spectrum transmissions).

The spectrum image has been done before by other people, but perhaps not in as much resolution.
The channel power measurement is the standardized one that I've checked about a dozen different 2.4Ghz RC systems with over the last few years, so it's 'Apples V's Apples' as much as it can be.
The result of the channel power measurement is no surprise to me, it's spot on where all CC2500 based systems are (with LNA chip), at around +21 to +22dBm. So V8FT is operating at 'normal' power level, which is I guess, 100% output.

For the non RF technical guys here, both images show 'good' data. Nice use of the whole 2.4Ghz spectrum with well distributed channels, power output is good too. Nothing bad to say about it really.

If anyone has tech questions about it or the instrument used please feel free to PM me.

PS. I forgot to mention, I measured the 'Range Check' mode power reduction, and its now -33dBc (on my own module). Previously I measured it at only about -15dBc on the Two-Way system TX module, V8FT apparently being the same.
So the new updated TX module firmware is much more useful in that regard, as found in my field checking too last week.
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Old Apr 28, 2010, 06:31 PM
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21~22 dBm? nice, so the output power is not 60mW, its 125~160 mW
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Old Apr 28, 2010, 10:31 PM
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I must be missing something.

Each 3dB reduction implies 1/2 the power and 1/4 the range. So -33dB implies 1/2000 the power and 1/4e6 the range. That would mean going from say 2000m to 0.5mm.

It's late and I am tired but I cannot see the mistake in my mathematics here, please show me.
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Old Apr 28, 2010, 11:10 PM
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St. Louis
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Hey guys I've had much success with my FrSky Module and 9cap radio... I just got back from the field flying my 50cc Goldwing Yak-55SP with the Frsky system and I can say its wonderful! Not a glitch, and all my controls were locked in. Like I said before, I have the Assan system but the 8ch long range RX cost more than the frsky module and RX combined! I will definitely be flying frsky for a while.

Ohh, I have the DLE-55 and the ignition has the extra lead for the digital tachometer how would you guys use the telemetry system to record or view this in real time throughout the flight?
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Old Apr 28, 2010, 11:38 PM
Martin - AKA mr.sneezy
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Adelaide, Australia
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Quote:
Originally Posted by kgfly View Post
I must be missing something.

Each 3dB reduction implies 1/2 the power and 1/4 the range. So -33dB implies 1/2000 the power and 1/4e6 the range. That would mean going from say 2000m to 0.5mm.

It's late and I am tired but I cannot see the mistake in my mathematics here, please show me.
I think the error is just the initial range value you used. 2000m is just the tested range we know it works well at, but the actual range to the point of total RX loss is probably much farther like 4km or 5km (in free space).

I just used this 2.4Ghz systems (WiFi) online calculator here to check as well, but sort of did it backwards.
http://www.swisswireless.org/wlan_calc_en.html
If you use the Path Loss calculator about 1/3 down the page and put in say 5km, you get a path loss of about -114dB. Using that as a start, if you use the other side of the calculator and then put in 33db more power (less link loss, -81dB) you get about 100m.
So when we reduce power by 33dB the 'maximum' range drops from around a theoretical 5km to about 100m. So in reducing the TX power by 33dB we need to move from say 4.5km away to just 100m before we would have the same signal level at the RX antenna.

I guess we now can predict the real range is going to be around 4 or 5km....
It very much depends on how accurate I was at measuring the range on low power...
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Old Apr 28, 2010, 11:57 PM
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5km is indeed the expected range in the air under ideal conditions for most IMS band RC systems with around 100mW EIRP and high sensitivity Rx. Simplistically though, -33dB would still mean a power reduction of (1/2)^11 = 2,000 which means range reduction of 2,000^2 = 4million so starting from 5km => 5000m/4million = about 1mm which is rather a lot less than 100m.

This indicates that the simplistic assumption that range is inversely proportional to the square of the power (ie expanding sphere from a point source) is not accurate in this case.
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Old Apr 29, 2010, 12:01 AM
Martin - AKA mr.sneezy
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Originally Posted by kgfly View Post
This indicates that the simplistic assumption that range is inversely proportional to the square of the power (ie expanding sphere from a point source) is not accurate in this case.
Yes agreed. I'll PM you about it as it's an interesting subject (to us at least).
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Old Apr 29, 2010, 12:12 AM
"...certainty is absurd."
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Joined Jan 2007
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Quote:
Originally Posted by kgfly View Post
5km is indeed the expected range in the air under ideal conditions for most IMS band RC systems with around 100mW EIRP and high sensitivity Rx. Simplistically though, -33dB would still mean a power reduction of (1/2)^11 = 2,000 which means range reduction of 2,000^2 = 4million so starting from 5km => 5000m/4million = about 1mm which is rather a lot less than 100m.

This indicates that the simplistic assumption that range is inversely proportional to the square of the power (ie expanding sphere from a point source) is not accurate in this case.
I'm just a mech guy, but shouldn't the range be reduced by somewhere between the square root of 2000 (circle), or the cube root (sphere), instead of squaring the power reduction?

If I use 2000^1/2.5, I get about 1/21 the range. For 2km at full power, that should be about 95m?

Kevin
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Old Apr 29, 2010, 04:45 AM
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Quote:
Originally Posted by kgfly View Post
I must be missing something.

Each 3dB reduction implies 1/2 the power and 1/4 the range. So -33dB implies 1/2000 the power and 1/4e6 the range. That would mean going from say 2000m to 0.5mm.
I think you have your 1/2 and 1/4 round the wrong way. 1/4 of the power would give 1/2 the range. So 1/2000 power equates to 1/44 of the range - ie 2000 yards at full power = 44 yards at -33dB.
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Old Apr 29, 2010, 12:53 PM
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Originally Posted by Sukalo View Post
Hi, did some one tray to connect RX to osd and get useful RSSI/lost package redings? Is there a way to get combined PPM signal drectly from RX for use in Mikrokopter?
Any news on the PPM signal yet guys? Same for me - mikrokopter.

I've asked the question of frsky - while they've answered another question quickly they've yet to get back to me on this one.

I do in fact have the diyDrones ppm encoder but not been able to get it to work as yet - I suspect due to something to do with the frsky rx but I don't have the know how to say exactly what.

Many thanks!
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