'Satellite' RX

[Basil]

I am a little confused about the need for a 'Satellite' RX. With some RX they include an outlet for a satellite  others dont !!!!!. If the capabilities are acceptable without why add a satellite... I have been reading the article re 'Lemon' RX , this further puzzles me . Just bought a 'Lemon' for the first time due to the rising costs of the Spektrum RX's( AR620).

Bas

Edited June 16, 2023 by Basil

[Dickw]

The aerials on 2.4Ghz are very short so the signal can be blocked by any onboard conducting materials such as engines, batteries, wires, and carbon reinforcing. Having additional “satellites” with aerials at different locations in the model will reduce the chance of loss of control by signal blocking.

It is probably not really needed in most models, but the option is there if you do need it.

 

Dick

[Basil]

Thanks Dick; I also forgot to ask about 'Diversity', ( the two little aerials on the RX ?????) My understanding is that the satellites are not then required. Even more puzzled.

Bas

 

Edited June 16, 2023 by Basil

[Cuban8]

When Spektrum first appeared on the market with satellite receivers, I heard many comments to the effect that " must be a rubbish system, because it 'needs' satellites". I know the brand did have certain other early issues, but I think the lack of technical understanding regarding signal diversity and why Spektrum went with satellites as opposed to others that didn't, unfairly caused a lot of unwarranted bias against the brand that even persists today.

I saw an early American 2.4 Futaba advert taking the mickey over satellite receivers by showing a distressed user of a 'brand X' radio entangled in wires and leads, while the Futaba user smiled his way through his flight suitably unemcumbered.

Did a search for it but doesn't come up - even as a Spektrum user for years now, I did find it a funny advert.

No external aerials at all seems to be the way forward by the look of it for Spektrum and others, so make of the original arguments what you will.

[Shaun Walsh]

36 minutes ago, Basil said:

Thanks Dick; I also forgot to ask about 'Diversity', ( the two little aerials on the RX ?????) My understanding is that the satellites are not then required. Even more puzzled.

Bas

 

Diversity is where your receiver will pair with any transmitter regardless of its chosen gender 🤣🤣

Edited June 16, 2023 by Shaun Walsh

[Dickw]

The receivers with 2 short (~30mm) aerials, or those with internal aerials, are the ones most likely to have the signal interfered with by conducting objects within the model, because all the "reception" is at one location. For example I know that any aerials inside some of my carbon fibre models just don't work at all.

 

Placing aerials some way apart and at different angles provides "diversity" in the point of reception and so reduces the chance of signal blocking. In the case of my carbon fibre models the aerials just have to be outside of the fuselage and clear of the wings. Using satellites or longer aerials (actually aerials at the end of a coaxial cable) are two ways of providing that diversity.

 

Obviously carbon fibre models and large models with large engines or batteries are a special case, and for most of my simpler balsa or foam models signal blocking is just not an issue.

 

Doing a decent range check while rotating the model through all angles will soon show you if you have  a problem.

 

Dick

 

[Shaun Walsh]

50 minutes ago, Basil said:

Thanks Dick; I also forgot to ask about 'Diversity', ( the two little aerials on the RX ?????) My understanding is that the satellites are not then required. Even more puzzled.

Bas

 

A diversity receiver has two separate antenna systems. The receiver constantly monitors the signal from both antennae and selects the one with the best signal.  Antennae are usually placed in different orientations wrt the model to minimise the chance of masking both at the same time.

Whether a satellite receiver is also required will depend upon the configuration and materials of construction of the model and how cautious the pilot is.