Techniques > Radios
Telemetry Transmitters
Fergal Gordon:
Hi Alan,
Thanks for the suggestions. The manual for the M-Link Tx module (HFM4 M-Link)) states the following:
"If you use a telemetry-capable receiver, the actual voltage of the receiver power supply is displayed on the transmitter’s integral screen. If the voltage falls below the set minimum value, an audible signal warns you that the battery is almost flat."
Section 12 of the same manual also states:
"The 2.4 GHz ISM band offers the facility to transmit model data
back to the transmitter. If you are using a telemetry-capable
M-LINK receiver, the actual voltage of the receiver power supply
will be displayed directly on the integral screen of your ROYAL-
evo, ROYALpro or ROYALpro M-LINK transmitter. If the battery
voltage falls below a certain threshold, the transmitter also emits
an audible signal to warn you that the receiver battery is almost
flat.
For more information on this feature, please refer to the opera-
ting instructions supplied with your telemetry-capable M-LINK
receiver."
The Tx module manual mentions "a certain threshold", but gives no indication of its level or how and where to adjust it.
The Rx manual in not any more informative either.
I have downloaded the MultMate manual and there is no sign of adjustment of the low Rx battery warning level. The is a threshold voltage level for counting voltage errors and this is adjustable. However, this is a different setting than the low voltage warning level.
There seems to be nothing in the main Tx manual in relation to telemetry or M-Link.
It is a bit of mystery how this feature is not well documented, given how well Multiplex generally document their products. One would expect that this setting should be in the model set-up, as each model could have a different battery pack and therefore would require its own low voltage warning level. Hopefully, this will be addressed in a future software upgrade.
Regards,
Fergal
Happy Days:
Just a thought Fergal,……
As I read what you’ve explained, you are using a 4 cell NiMH battery . As you probably already know, the nominal working voltage of such a battery is 4.8v. So I’m wondering why Multiplex would want to warn you about the state of charge of your battery when it’s operating at its correct voltage. :?: (I’m assuming it would only emit a warning if the voltage was low.)
Therefore, I’m thinking, that perhaps the warning alarm assumes that you would be using a 5cell battery (Which has a nominal voltage of 6v.) The reason being is that if the voltage on a 5cell battery were to drop to 4.8v then it would be at a low state of charge.
In other words, I’m suggesting that maybe the system assumes you’re running with a 5cell battery.
Solution = use a 5cell battery?
Wot d’ y’ fink?
Happy Days:
I’ve just done some on-line searching and the above is irrelevant. :roll:
I can’t actually find an on-line manual for your Tx but I did turn up the following Fergal which states that the warning voltage of the Rx battery is variable,…
"Feedback channel / Telemetry
If you use a receiver with telemetry facilities (min. RX-7-DR M-LINK or RX-9-DR M-LINK), the actual voltage of the receiver power supply is displayed on the transmitter screen. If the voltage falls below a (variable) minimum value, an audible warning signal alerts you that your receiver battery is almost flat. This means that you are constantly aware of the state of the receiver battery, as well as the condition of the transmitter battery (as previously). An important extra safety feature!
See page 21 for details of telemetry sensors."
That’s all I could find written in English. But just refering to my previous post I recon at present your system is set up assuming that you’re using a 5 cell rx battery because with a 5cell, 4.8v is the level of a discharged battery
I know that’s not much use to you, but it’s the best I can come up with old fruit.
Keith
Fergal Gordon:
Hi Everyone,
Thanks for all the help. I am beginning to think the voltage threshold for the low Rx voltage error count is the same threshold for the audible warning on the Tx. The default setting is 4.5 V, which on face value is a reasonable level. However, I have done some tests on the ground, where I can focus on what is happening on the Tx screen. I would appear that when there is an increased current draw, e.g., several servos moving fast, the voltage can momentarily drop by 0.3 to 0.4 V below its steady level.
When I am flying, it would appear the steady voltage first drops to about 4.8 V. Then there is a momentary drop to the threshold voltage of 4.5 V. I then level the plane, centre the sticks and when I look at the Tx screen I see 4.8 V.
If this is correct, then all I need to do is reduce the threshold voltage down to between 4.0 and 4.2 V. The receiver will still work down to 3.5 V, so reducing the threshold to 4.0 V should not be problem. I just need a MultiMate to program the receiver.
Best regards,
Fergal
Alan_Perse:
--- Quote from: "Fergal Gordan" --- I am beginning to think the voltage threshold for the low Rx voltage error count is the same threshold for the audible warning on the Tx.
--- End quote ---
Forgive me Fergal if you know this already, but isn't the voltage of the TX battery 7.2V. If you set the threshold to 4.8V you will lose power before you get a warning.
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