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Old Aug 09, 2008, 03:04 AM
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Thailand
Joined Apr 2006
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<<yes I have an idea, send me the trainer connector you have my address,
or direct my to a place I can purchase this special connector,
then I try to borrow a T9CHP from a club member, then I measure the PPM pulses and test if compatible, if not I find a workaround>>



Great
I will sent one to you.
Really love your service.
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Old Aug 09, 2008, 04:49 AM
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Madrid, Spain
Joined Mar 2006
763 Posts
Quote:
Originally Posted by Carlyle Harper
I have a 9ZAP WCII and currently use a tm-7 FASST module in it with absolutely no problems for normal flying.

However it has been reported here:

http://www.rcgroups.com/forums/showt...3&highlight=9z

that some 9z's have a problem with the ppm stream. I have no idea if mine is affected and I'm not exactly sure what a ppm pulse is or consists of. I just know it has been known to cause a problem with non futaba modules, but I'm sure you know exactly what the pulses are. So do you know if your system will be able to work with a 9z?
havenīt had time to read the post you quote there about 9Z ppm signal levels, but I can tell you that with my 12fg there is a problem about ppm signal VPK-PK is around 2,8V a bit low. All I did was a simple transistor buffer and raised those levels at 4VPk-Pk
I assume something similar is happening with the 9Z
Those levels are too low for using certain modules as 868mhz, etc, not to flight with usual r/c gear.
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Old Aug 09, 2008, 05:10 AM
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2.8V is fine with me, as long as it is 2.8V over GND ?
and not floating some where 3-5V ?
my PPM input signal goes into a 3.3V microcontroller, after a pull up resistor, 100k
and a series resistor 270 ohm, and a 3.3V zener protection diode.
so I guess a 2.8V PPM signal will work just fine with me.
lets see a scope picture ?
try to load the signal with 100k to gnd and to + battery voltage ?
to indicate if the signal is super high impedance and can maybe not handle any load ?
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Old Aug 09, 2008, 06:05 AM
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Madrid, Spain
Joined Mar 2006
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Quote:
Originally Posted by thomasscherrer
2.8V is fine with me, as long as it is 2.8V over GND ?
and not floating some where 3-5V ?
my PPM input signal goes into a 3.3V microcontroller, after a pull up resistor, 100k
and a series resistor 270 ohm, and a 3.3V zener protection diode.
so I guess a 2.8V PPM signal will work just fine with me.
lets see a scope picture ?
try to load the signal with 100k to gnd and to + battery voltage ?
to indicate if the signal is super high impedance and can maybe not handle any load ?
Yes 2.8V over gnd, I attach an scope pic below, unfortunatly canīt do those test you propose because Iīm not at home till next week. Will do it though
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Old Aug 09, 2008, 06:33 AM
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thanks alot, that PPM looks just fine,
are you sure it uses a fixed repeat time ?
ok that repeat time will change if you change the number of channels :-)
but try to move the sticks and see if the repeat time is constant.

videos ? someone requested a clip, now look at the bottom of the page:
http://www.webx.dk/rc/uhf-link3/uhf-link3.htm
comments welcome as always.
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Old Aug 09, 2008, 06:43 AM
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Ok will try it too when I get home but if I remember well the repeat time varies if you move the sticks .
How far have you achieved in real flights?
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Old Aug 09, 2008, 06:57 AM
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the PPM pulse train varies in time when you move the sticks,
but the repeat time is constant, right ? please check ?
that is normal on digital radios and a MUST to be able to use this system !

range, well it is not legal in my area to fly far far away,
I spend most of my time developing and soldering, not flying (sorry)
and only a few customers so far, but one had 5km, then video range problems,
but still fine RC,
if I calculate the line of sight range even at 500mW it gives me 100km,
but those calculations think we have 100% no noise on the band,
and a perfect line of sight, that is not possible in the real world :-)

so in real life I think the 500mW standard version will give you 5-10km
depending on installation and antennas, good/bad antenna used on the TX side,
can halve or double the 5-10km range.
the default standard TX antenna supplied is considered to be cheap and easy to get and small fit into parcel, but bad when it come to range, if you need over 5km range I suggest using better TX side antenna or simply use the booster option.

the 7W booster option will x3 the range you had before if nothing else is changed.

if you need over 5km range you have to do something special about the Video link and antennas used to get good stable and noise free pictures.
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Old Aug 09, 2008, 06:59 AM
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also added this:
Long Range UHF RC system (0 min 30 sec)
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Old Aug 10, 2008, 09:07 AM
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NEW:
http://www.webx.dk/rc/uhf-link3/competition.htm
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Old Aug 10, 2008, 09:29 AM
BEOWULF
North vancouver, B.C. Canada
Joined Apr 2008
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Thomass you are a guru
I started looking for systems not too long ago and one thing told to me was, take my time, look around!
One day too late for me, wish i bought yours instead
I also love reading your posts
very smart Thomass very smart
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Old Aug 10, 2008, 09:31 AM
BEOWULF
North vancouver, B.C. Canada
Joined Apr 2008
18,084 Posts
Here is my entry Thomass, could we not cheat and use a relay positioned at a long distance from the flying site. So when we fly past the relay we can go that much further.?
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Old Aug 10, 2008, 09:44 AM
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Sorry about that david, one day too slow :-) sell it used, and puchase a new ?
range cheat:
if you locate the RC uplink (you) say 5km from plane take off site,
then fly AWAY from your own location, that could be a good way to achive 10km distance and only use battery power for 5km.
but if you fly towards yourself the first 5km is wasted battery, it is the RC RADIO range we want to see, not the plane flyning time and distance of only the plane,
if that was the case simply take an open car, sit there and RC your plane while a helper drives the car, then you see how far the plane can go.
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Old Aug 10, 2008, 09:45 AM
BEOWULF
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now that is cheating lol
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Old Aug 10, 2008, 09:53 AM
fast
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this makes no sense cause there are no video TX/RX to match UHF range.
esp. since 900MHz video probably won't work
also powerful 2.4ghz video may drive your RX crazy unless you redesign RF section into metal can(shield). 2.4ghz mean 28mm 1/4 wavelength that can find same length PCB trace to resonate.
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Old Aug 10, 2008, 10:46 AM
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>this makes no sense cause there are no video TX/RX to match UHF range.

exactly that is why it is so perfect to use this band for long range RC systems,
it is also a normal known fact: the lower frequency the longer range,
so why dont we have good range on 35Mhz ? the frequency is soo low !
that is why we use 1/8 wave length antennas they are unefficient and we use really low power and at the same time most receivers dont have good sencitivity.

>esp. since 900MHz video probably won't work

why not ?
900MHz video is known to jamm GPS receivers, so that is bad too,
and 900MHz video wont work with 868Mhz based RC systems too,
frequency simply too close.

>also powerful 2.4ghz video may drive your RX crazy unless you redesign RF >section into metal can(shield). 2.4ghz mean 28mm 1/4 wavelength that can >find same length PCB trace to resonate.

the rf secrion of the receiver is specially designed to handle 2.4GHz video transmitters near by, no customers have been able to indicate any range loss due to video TX at 2.4, the boards them self are actually quite well shilded, removing the antennas the range is only a few meters this indicates also traces and components dont pick up radio signals well, that is quite amazing when the receiver have a -110dBm sensitivity, adding a shield case in this design is waste of cost and weight.
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