Graeme White Posted February 22, 2021 Share Posted February 22, 2021 Morning all. After getting thoroughly confused with frsky changing protocol after needing some new receivers for some newly acquired models I got myself 2x radiomaster r168 after hearing good things. Binding was no issue, failsafe will sort however in the instructions they say about fine tuning the receiver frequency? I have a qx7 transmitter and cannot find anywhere with this option and Google is no help as always when it comes to taranis. Is this necessary? Is it possible? So confused. I just want to fly and this stuff is all very confusing. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 22, 2021 Share Posted February 22, 2021 (edited) Interesting. According to the website shown at the bottom, there is a long list of protocols that require tuning when using a Multi Protocol Module. I use a Jumper 4in1, so I assume that it applies to them. I wasn't aware of this but I'll be looking into it. Regarding where to find the option, that screen looks like the Model Setup screen used for binding in OpenTX. https://www.multi-module.org/using-the-module/frequency-tuning Edit. No I don't use the Jumper 4in1 for native FRSky products and neither does your QX7. We use the internal module. This procedure is for using MPMs including Radiomaster transmitters, with the listed types of receiver. Edited February 22, 2021 by Gary Manuel 1 Quote Link to comment Share on other sites More sharing options...
Brian Lambert Posted February 22, 2021 Share Posted February 22, 2021 I think this applies to the Radiomaster transmitters with the multi protocol module. But please do a range check before flying. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 22, 2021 Share Posted February 22, 2021 (edited) It's for any transmitter that uses a MPM I believe. Tuning is not an option in the "Internal Module" in FRsky transmitters, but the Radiomaster ONLY uses an MPM as it has no native protocol. Edited February 22, 2021 by Gary Manuel Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 22, 2021 Share Posted February 22, 2021 This is worth noting (from the link in my first post). Quote Link to comment Share on other sites More sharing options...
EarlyBird Posted February 22, 2021 Share Posted February 22, 2021 Having just set up my Jumper 4in1 multi module for a Hitec rx I had missed the fine tune. and now there it is. Thanks to this thread I will now fine tune. Thanks Quote Link to comment Share on other sites More sharing options...
Sheepish Posted February 22, 2021 Share Posted February 22, 2021 Hi Graeme I’ve just done this with my QX 7 and Radiomaster R168. My QX7 is running ACCAST V1 Eu LBT firmware as I haven’t updated to the new v2 as I have seen no problems with the v1 firmware I have loaded. I loaded the R168 with the firmware for an Frsky X8R, again the v1 version as when I tried the Radiomaster rx to start with nothing happened and I think it was probably loaded with the universal FCC firmware as it came from Banggood. The new R168 firmware was loaded using the connection on the base of the QX7 linked to the S port on the receiver exactly the same as I would for an Frsky receiver and the firmware was on the SD card in the QX7 as normal. The binding process was straightforward and works the same way as binding to any other FRsky X8r or similar receivers. The range seems OK and the telemetry works. No chance to fly the combo yet due to lockdown but it all looks good so far. If I can help with any further detail please let me know. Quote Link to comment Share on other sites More sharing options...
Graeme White Posted February 22, 2021 Author Share Posted February 22, 2021 Ah OK, thanks all. So sounds like using just the standard pre access q7 with nothing fancy in the back I should be OK. I will definitely range check once the field opens back up again ? I haven't dared Flash anything with anything else as it works now and I'm not into the technical side of radios. Quote Link to comment Share on other sites More sharing options...
Mike Blandford Posted February 22, 2021 Share Posted February 22, 2021 To give some background to all this. Both a Tx module and a Rx rely on a crystal oscillator to provide an accurate frequency reference. The exact frequency then used to transmit and receive is derived from this. It appears that FrSky modules and receivers use a crystal that is very accurate so any module works with any receiver. It also appears that the crystal in MultiProtcol modules, for the CC2500 RF chip, is less accurate, hence the requirement for fine tuning of the frequency. I don't know the accuracy of the crystal in the R168. One of my MultiProtocol modules needs a fine tune value of -40 and another needs +40. If I use the one that needs -40 with a setting of +40, then it won't bind or operate servos. If someone has both FrSky receivers and R168 receivers, and a MultiProtocol module, it would be useful to test the MPM with both receivers and see if you need the same fine tune value for all receivers. If you need a significantly different value for the R168, then I would suspect the R168 crystal is less accurate, and would question if it was good enough to use with a FrSky Tx module, more testing would be indicated. Mike 1 Quote Link to comment Share on other sites More sharing options...
MattyB Posted February 22, 2021 Share Posted February 22, 2021 (edited) Further to Mike's excellent post above, here are some good resources on the fine tuning process on an MPM based radio... Multiprotocol Module Frequency Tuning - YouTube RadioMaster TX16S The Need To Fine Frequency Tune FrSky Receivers - YouTube Oscar Liang written guide to frequency fine tuning Edited February 22, 2021 by MattyB 1 Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 22, 2021 Share Posted February 22, 2021 Thanks for the info Mike. May I ask a related question? How come it's only certain protocols that need the fine tuning? Why not DSM2 for example? I have a vested interest in this because I use my MPM (with Horus s12) exclusively for my Spektrum / JR receivers. Quote Link to comment Share on other sites More sharing options...
Mike Blandford Posted February 22, 2021 Share Posted February 22, 2021 It is only those protocols that use the CC2500 RF chip. I virtually certain each of the 4 RF chips use their own crystal/oscillator. I don't know the accuracy of the frequencies for the other three RF chips and I haven't tested them and I don't think they have a fine tune facility. Mike Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 22, 2021 Share Posted February 22, 2021 Thanks again Mike. I certainly have no reason to doubt the compatibility of my MPM and DSM2 receivers. I have another observation / question for you about a post you made some time ago, which must have made an impression because I remembered it. I can't normally even remember where I put my glasses. In the following thread, you commented that an MPM using CC2500 had a lower transmitted power than a FRSky module. Is it possible that this was actually a measure of received power due to an out of tune MPM? Quote Link to comment Share on other sites More sharing options...
Mike Blandford Posted February 22, 2021 Share Posted February 22, 2021 No I don't think so. I believe I had done the required tuning before doing that test. In any case, I definitely see lower RSSI values with the same receiver on a MPM (I have several) compared to a FrSky module. I don't know what power amplifier the MPM is using, but it may have a lower gain compared to the one FrSky use, and there may be more losses due to switching the RF signal between the four RF chips. The CYRF chip (used for DSM) is set to +4dbm power output while the CC2500 is set to +1dbm (the max possible), so the DSM output is likely to be double that of FrSky in the MPM. It is even possible that the DSM output exceeds 100mW! I don't know what the gain of the antenna on the MPM is. I've understood that FrSky use a 2db gain antenna. Mike Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 22, 2021 Share Posted February 22, 2021 Thanks once again Mike. This makes perfect sense and gives me some reassurance that MPMs can offer comparable range to the original manufacturer's equipment. This is one of the things that I love about forums like this and the internet in general. You are never far away from someone with the knowledge you are lacking and is willing to share it, or point you in the right direction. People like you are what make it possible. ? 2 Quote Link to comment Share on other sites More sharing options...
Brian Lambert Posted February 23, 2021 Share Posted February 23, 2021 (edited) 12 hours ago, Mike Blandford said: The CYRF chip (used for DSM) is set to +4dbm power output I am confused 4dbm is only 2.5mW this can't be the out put power can it? It must be amplified for output and therefore the P.A. power would be more relevant. I told you I am confused! Edited February 23, 2021 by Brian Lambert Correct grammar Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 23, 2021 Share Posted February 23, 2021 (edited) 33 minutes ago, Brian Lambert said: I am confused 4dbm is only 2.5mW this can't be the out put power can it? It must be amplified for output and therefore the P.A. power would be more relevant. I told you I am confused! I'm not confused. The +4dBm and +1dBm are the output power of the two chips. Mike has quoted them just to show that the DSMs CYRF chip has double the power output (3dB) of the FRSkys CC2500 chip. Both signals do indeed need to go through the RF amplifier before reaching the antenna. As the RF amp and antenna have a fixed gain, the DSM will still be 3dB higher than the FRSky when it is transmitted, but at a much higher power level than when it left the chip. Edited February 23, 2021 by Gary Manuel Quote Link to comment Share on other sites More sharing options...
Brian Lambert Posted February 23, 2021 Share Posted February 23, 2021 Now I know nothing about the workings of these transmitters, but wouldn't the designer put a 3db attenuator on the higher output chip so that all protocols would benefit from the full output power allowed? Just a thought. Quote Link to comment Share on other sites More sharing options...
Mike Blandford Posted February 23, 2021 Share Posted February 23, 2021 Not needed as all the RF chips have a programmable output level, just change the firmware to reduce the output power on the higher output chip. I think the problem is that RF signals are tricky to lay out on a PCB. You need to match the antenna characteristics to get the best power transfer. Having 4 separate RF chips being made to switch into a single amplifier and antenna is difficult, it is very easy to have losses so some chip outputs end up weaker than might be possible with a single chip. Mike Quote Link to comment Share on other sites More sharing options...
Balazs Posted March 8, 2021 Share Posted March 8, 2021 Good Afternoon All, I have an issue related to the topic you have been discussing. I have a Taranis QX7 EU version and have been using it with X8R receivers for a long time, no issues so far. I recently bought 2 Radiomaster R168 receivers and could successfully bind both with the Taranis QX7. They seem to work for a short period of time but suddenly they lose signal and telemetry every other second. Both R168 behave the same way however they are from different sources and one of them was with a non-EU firware so I first had to flash the EU-version to it. I also googled for Frequency fine tuning but I could find nothing related to Frsky and no options within the transmitter either. Does anybody have any idea what the issue can be? Is it b/c of frequency mismatch? I can hardly believe that both receivers are faulty (tehy are from different sellers) and show exatly the same symtoms... The problem is so serious that none of the receivers can be used as they are extremly unstable. I am at the point of throwing them away.... Any idea, help is much appreciated. Many thanks Balazs Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 8, 2021 Share Posted March 8, 2021 (edited) I would try flashing the most up to date version of the RF firmware for your transmitter and see if that stabilises things - my suspicion is that it is a. RX/TX firmware mismatch issue. The Frsky X7S download page is here, though my PC is struggling to get to it at the moment. Make sure you choose the right version for your RXs (v1 or V2 ACCST). If that doesn't fix it I'm not sure what to suggest; there is no frequency tuning option on the Frsky radios, that is an MPM feature only. Edited March 8, 2021 by MattyB Quote Link to comment Share on other sites More sharing options...
Balazs Posted March 9, 2021 Share Posted March 9, 2021 Dear MattyB, thank you for the hint. I flashed the latest FW to my Taranis QX7 (it is not an S version but I believe it is irrelevant in this case). Then I tested both R168s. The issue is still there, slightly better but the connection is still so unstable that I would not go out with this receiver. checking the RSSI signal level it is around 57-61 instead of ~80). I believe there is a frequency mismatch between the TX and RX. I think I go back to the good old Frsky X8R receiver, it is 3 times more expensive but at least works. Thank you again for your support. Quote Link to comment Share on other sites More sharing options...
Torsten Spitzner Posted March 9, 2021 Share Posted March 9, 2021 2 hours ago, Balazs said: Dear MattyB, thank you for the hint. I flashed the latest FW to my Taranis QX7 (it is not an S version but I believe it is irrelevant in this case). Then I tested both R168s. The issue is still there, slightly better but the connection is still so unstable that I would not go out with this receiver. checking the RSSI signal level it is around 57-61 instead of ~80). I believe there is a frequency mismatch between the TX and RX. I think I go back to the good old Frsky X8R receiver, it is 3 times more expensive but at least works. Thank you again for your support. I have similar issues with my Horus and two R168 receivers. Random telemetry and signal loss and servos that suddenly move to their extremities at random. I have tries all manner of firmware updates but the issues persists. These Two receivers are now banished to the workshop desk drawer. I will also stick to the Frsky receivers... Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 9, 2021 Share Posted March 9, 2021 3 hours ago, Balazs said: Dear MattyB, thank you for the hint. I flashed the latest FW to my Taranis QX7 (it is not an S version but I believe it is irrelevant in this case). Then I tested both R168s. The issue is still there, slightly better but the connection is still so unstable that I would not go out with this receiver. checking the RSSI signal level it is around 57-61 instead of ~80). I believe there is a frequency mismatch between the TX and RX. I think I go back to the good old Frsky X8R receiver, it is 3 times more expensive but at least works. Thank you again for your support. NP, sorry it wasn't successful. One final thought... Have you got access to an MPM based radio? You could try those RXs with that, do the frequency tune and determine if the RXs are faulty or if it was just a tuning issue between TX and RX. If you like you can send one to me - I'll buy it off you for what you paid for it (was going to try one of these anyway) and test it with my Radiomaster TX16. Quote Link to comment Share on other sites More sharing options...
Balazs Posted March 9, 2021 Share Posted March 9, 2021 Dear MattyB, Thanks for the proposal. I have no access to MPM based radio, I can send one of the R168 to you, you dont need to pay for it. I would just simply keep it in the drawer with no use...If you can tune and use it at least it is not wasted. Just give me a contact where I can send it by mail. My email is balazsdotgyore1atgmaildotcom. Cheers 1 Quote Link to comment Share on other sites More sharing options...
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