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Old Feb 13, 2013, 04:22 PM
59 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
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Quote:
Originally Posted by Terry Rigden View Post
Pardon my ignorance but I dont know what those acronyms mean. We just want a warning beep when we get to the limit of range.

Terry

CPPM: Combined PPM
Means that the entire PPM stream (all 8 or however many channels) is available from a single output on the receiver, by contrast with the usual splitting up into separate channels for the various servos.

RSSI -- Receiver Signal Strength Indicator
RSSI is an indication of the power level being received by the antenna.

RSSI is exactly what you want. By the way, it's not as simple as "limit of range". The signal strength varies not only with distance but with the alignment of antennas and other factors. So hearing occasional beeps is to be expected. That's why there are at least two levels of warning.
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Old Feb 13, 2013, 04:39 PM
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Quote:
Originally Posted by Daedalus66 View Post
RSSI is exactly what you want.
I think you might be confusing him. Yes, he wants "Receiver Signal Strength Indicator", but No, he does not need receiver with RSSI output (D8R-XP). This "beep" indication is done be TX module itself based on telemetry data it gets from receiver. (In fact it checks also strength of telemetry signal A.K.A. downlink). ALL FrSky telemetry receivers send signal strength information back, so receiver with RSSI output is not needed. You need such receiver only if you need to know signal strength in the plane itself, for example for some extra devices in aircraft/copter that use it for "something special" (mostly for copters/FPV/UAV).
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Old Feb 13, 2013, 07:30 PM
59 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
15,763 Posts
Quote:
Originally Posted by mihlit View Post
I think you might be confusing him. Yes, he wants "Receiver Signal Strength Indicator", but No, he does not need receiver with RSSI output (D8R-XP). This "beep" indication is done be TX module itself based on telemetry data it gets from receiver. (In fact it checks also strength of telemetry signal A.K.A. downlink). ALL FrSky telemetry receivers send signal strength information back, so receiver with RSSI output is not needed. You need such receiver only if you need to know signal strength in the plane itself, for example for some extra devices in aircraft/copter that use it for "something special" (mostly for copters/FPV/UAV).
You're quite right of course. I was just thinking of the definition, not the context.
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Old Feb 14, 2013, 01:39 AM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
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Thanks guys so so plain simple signal strength warnings its OK right out of the box

Terry
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Old Feb 14, 2013, 07:34 AM
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cold wombat's Avatar
Australia, WA, Perth
Joined Jul 2011
273 Posts
Thanks mihlit & renatoa for those explanations; It's really helped get my head around it. Bit by bit this stuff is all falling into place.


Quote:
Originally Posted by mihlit View Post
In short: D8R-XP is there for those, who need RSSI and CPPM. If you need it, you know what it means. If you don't know what it means, then you don't need it and D8R-II plus is the one for you (you can use D8R-XP too, but the cheaper one suffices).

To satisfy your hunger for knowledge:
CPPM contains data of all eight channels, it's used when you want to connect your receiver with some controller board (flight stabilisation for wing aircraft or controller board for copter). RSSI changes value according to signal strength. It's used mostly for FPV fliers so some other device can add signal strength icon to transmitted video signal. Also it can be used for copter controller boards to trigger RTH (return to home).
Quote:
Originally Posted by renatoa View Post
CPPM and RSSI are for FPV/UAV and multicopter guys, which are not newbies, or shouldn't... without feeling a bit insecure
They share the same hardware, the two receivers I mean. XP is only a firmware, and can be loaded by the user when he needs those features.
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Old Feb 15, 2013, 03:15 AM
Foam Snow
South Africa, WC, Cape Town
Joined Aug 2011
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Quote:
Originally Posted by pmackenzie View Post
Did you mention you were doing FPV earlier?
I haven't

Quote:
Originally Posted by pmackenzie View Post
What frequency is it on and how much power?
5.8, 500mw

Quote:
Originally Posted by pmackenzie View Post
How does it behave with the video turned off?
Impossible to tell - I can hardly see my wing 500m away let alone 1km

Changing the orientation of one of the antennas to vertical showed improvement.

The most likely theory is carbon fibre showing.

I think I have three options - stay within 500m, boost signal or use patch.

Thanks for everyone's input.
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Old Feb 15, 2013, 05:07 AM
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The Fens, Britain
Joined Nov 2005
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Quote:
Originally Posted by mihlit View Post
I think you might be confusing him. Yes, he wants "Receiver Signal Strength Indicator", but No, he does not need receiver with RSSI output (D8R-XP). This "beep" indication is done be TX module itself based on telemetry data it gets from receiver. (In fact it checks also strength of telemetry signal A.K.A. downlink). ALL FrSky telemetry receivers send signal strength information back, so receiver with RSSI output is not needed. You need such receiver only if you need to know signal strength in the plane itself, for example for some extra devices in aircraft/copter that use it for "something special" (mostly for copters/FPV/UAV).
So of the two "RSSI" bars on the FLD-02, the left-hand one (Rx RSSI) relates to signal seen by the Rx and reported to the Tx, while the other (Tx RSSI) reports the quality/strength of the telemetry signal seen by the Tx?

So the left-hand one is important for safety?
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Old Feb 15, 2013, 12:04 PM
Expat
Japan
Joined Apr 2010
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I was very impressed with the FRSky system reports - the cost is way less than I thought. IIUC, for about $50 (+$15 shipping) I can get the futaba module and an 8 channel RX with anteena extensions that works with signal strength beep thingy (telemetry) out of the box. This is reported to convert my old F8U perfect.
I assume 5.8 or 1.3 with the special filter thingy is the preffered FPV signal. 1.3 sounds superior due to signal constitution. Sounds like 1km + as-is is easy with this settup. Why aren't more people useing them? Or am I missing something?
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Old Feb 15, 2013, 12:25 PM
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Romania, Dolj, Craiova
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Frsky RC receiver is more sensible than average receivers, and this sensitivity has also drawbacks, it is sensible also more to the second harmonic of 1.2G video.

Also, 1.2G bigger antennas are not a bless...

Not the last, this theory of range being proportional with frequency is overrated and true only on moon, not in real world.
4x difference between 5.8 and 1.3G means 12dB.
The receivers of both systems are rated at about -90dB sensitivity, so no change here.
But... to allow a receiver to increase his gain up to the maximum, you must have a low noise floor of the area where you fly. Here is the big difference... 5.8GHz especially the upper part, is a really virgin ground, you must see to believe how crystal clear could be the image, while 1.2-1.3GHz is flooded in urban areas by all wireless cameras of various security systems, which transmit in this band.
12 dB is very easy to be lost in such environments.
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Old Feb 16, 2013, 12:40 AM
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I am hoping to output rssi from the D8R-XP to the Storm OSD. Frsky instructions say jumping Ch3 & 4 will output rssi to ch 2 and CPPM to ch 1. Presumably for this to work the OSD must support a CPPM input. There is no such input on the OSD. Can someone explain or point me in the right direction? Thx.
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Old Feb 16, 2013, 01:11 AM
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Romania, Dolj, Craiova
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You can move your main channels to ports 5-8, if your radio allows this.
Using mixers or elsewhere.
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Old Feb 16, 2013, 01:14 AM
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Joined Oct 2011
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Quote:
Originally Posted by Breezy View Post
So of the two "RSSI" bars on the FLD-02, the left-hand one (Rx RSSI) relates to signal seen by the Rx and reported to the Tx, while the other (Tx RSSI) reports the quality/strength of the telemetry signal seen by the Tx?

So the left-hand one is important for safety?
I'm not sure which one of them shows strength of the signal that RX gets. Also I don't see a point in differentiating, uplink(control) and downlink(telemetry) they use the same antenna. There is usually small difference between them and once you have no telemetry signal, you won't get any information about signal strength from receiver.
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Old Feb 16, 2013, 11:11 AM
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That means giving up my pan and tilt. Any other options to preserve two other channels? It would seem like a waste to see the combined signals for the 8 channels left redundant in ch 1. Another alternative would be to revert to Frsky telemetry at range limits but that appears to be an inferior strategy. Any further help would be great.
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Old Feb 16, 2013, 12:02 PM
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Romania, Dolj, Craiova
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Alternatives, a lot:
- V8FR receiver with green LED tap method
- D8R receiver with external add-on board sold on ebay by a Hungarian fellow
- wait for LR9 long range receiver with dedicate RSSI port
- use acoustic RSSI warn, they are accurate enough for return home, not needed to be in the OSD
- use a serious OSD, all are CPPM based
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Old Feb 16, 2013, 01:13 PM
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Joined Mar 2012
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Thanks for these options. Very helpful after hours of searching online to no end. Much appreciated.
Options 1 & 2 - I will check them out
Option 3 - Very pleased to know there is something plug & play on the horizon, any idea when?
Option 4 - You mean the Frsky telemetry beeps? Q: If I use a booster would the receiver be able to send back the warning signals back to the tx with the extended range? If not would there be audible beeps in the plane that I can hear through the audio of my vtx?
Option 5 - I will look more into it.
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