Frequency Hopping Spread Spectrum vs. Dual Band
 

I need some technical expertise on this question. With our remote control product, we use a frequency hopping spread spectrum (FHSS) two-way transmission system on 5 channels of the 433 MHz band. The signal is designed to hop 5x per second.

Our competitor uses a dual band, one-way system on 433 MHz and 916 MHz (although they only have FCC approval on 868 MHz - another story).

They are basically claiming to the unknowing public that "two bands are better than one," and that FHSS is archaic technology since it was initially developed many decades ago.

I am hopeful that I can find an RF transmission expert who can provide me with proof, in the form of some type of clear and easily understandable example, which shows the benefits of two-way FHSS vs one-way dual band.

Thanks in advance for your assistance!

Single band was utilized by Tesla over 100 years ago. Dual band is just two single frequencies.

The concept of spread spectrum originated in WW2, but was not put into widespread practice until the 1960s, and really came into its own in the 1990s.

There are nice things about using two bands, but spread spectrum has a lot of advantages as well.

When Spektrum developed DSM, originally it was a single frequency system for cars and then later for airplanes in the DX6 Parkflyer System. DSM2 was two frequencies that were alternately used, and was the basis for our first full-range products suitable for any aircraft. It worked great up until we had a hundred pilots flying at a time, in events like Joe Nall. DSMX was developed to address the issues of using only 2 frequencies - it uses 23 frequencies, and is the leading model control protocol in the world.

If you want mathematical proof for the superiority of spread spectrum, I suggest you turn to your local university's math and electronic engineering departments.

Andy

Thanks for your reply and suggestion. I need simple, easy to understand proof that I can present to the boating public.

I thought about mentioning that FHSS is commonly & widely used with Bluetooth and Wi-Fi, which everyone has certainly heard of. To the best of my limited knowledge, Dual Band is not often used for any recent devices or technology, and definitely not with something so important as wireless remote control of a small boat or yacht.

True or untrue?

Your phone probably supports FHSS WiFi on two bands - 2.4 and 5.8. For each, it's only connecting to one or the other, and is thus single band FHSS once running, but it has two bands available to it. If one is overloaded (usually 2.4) then you can tell it to move to 5.8, but it's usually a manually-selected thing (though it can be automatic).

The truth is, there are advantages to both. The best solution would be multiple bands, frequency hopping within each. That is, technically, just a matter of expanding the spectrum of allowed frequencies.

Since you're talking boats, you especially need to understand the problems of operating 2.4gHz over water and how greatly it diminishes range. It is far from the best band to use. Right there your competitor has a huge advantage because 433 & 868MHz are going to have much better performance over the water, but you being on 433 isn't an issue.

Andy

Note also that 5 frequencies, though much better than 1, is hardly taking advantage of spread spectrum. And hopping at 200ms intervals isn't much of a spreading. The ability to use more channels more quickly is where you start to see the benefits of spreading. Jamming (whether intentional or not) is far more difficult if you spread out shorter bursts over wider area more frequently.

Andy

Hi Andy,

We have a two-way system (transceiver + receiver) that uses a FHSS transmission over 5 channels on 433 MHz. The competitor uses a one-way system (transmitter + receiver) on a dual band system that actually uses 433 MHz and 916 MHz. They have FCC approval on 868 MHz, but not on 916 MHz.

The transceiver + receiver signal "hops" over 5 channels at a rate of 5x per second.

Thoughts?

Thanks again,
Brian

See previous reply. You replied before you read my second post.

Andy

Thanks again Andy,

I am wondering if we hope continuously over the same 5 channels on 433 MHz and stay on those 5 channels only, or if we hope 5 channels, and then another 5, and so on.

Much appreciated!

How many channels are in your spectrum? How tightly are your channels transmitted? How selective is your receiver? How long are your transmissions? How do you determine which channels to use and when? How much spare bandwidth do you have?

What's your website? I'd love to see what you're doing now, how you document it, etc.

Andy

I understand that Yacht Controller has taken my comments out of context on their FB page: https://www.facebook.com/YachtController/

I don't do FB so I can't see it myself.

When dealing with companies selling RF products, be sure they are licensed to use the frequencies they are on, and that their products have genuine FCC labels. You can always look them up on the FCC website. https://fcc.report/FCC-ID/

Operating unlicensed equipment can get YOU a fine. Selling unlicensed equipment gets THEM a fine.

Andy

He took it to the public alright(post #3). He linked this thread to their FB page, to promote their product obviously. The guy was fishing for someone to put it in writing, and endorse a product, in a rather deceptive way. When he got what he wanted he threw it up on his FB page.

This is a very distasteful business practice in my opinion. At the least the original poster should have disclosed to anyone that replied that this thread would be used for propaganda and promotion....It's definitely not a public service announcement.

Andy, you need royalties on whatever product you just unknowingly endorsed. You're expert opinion is definitely worth something you know... I would say a very substantial amount.

At least the "public" can read the whole thread and decide for themselves. This kind of campaign can be a double edge sword. Does anyone really want to biz with the guy?.. LOL
I would also concur, check licensing before doing business with the guy. Anyone who deceives like this can likely deceive in other ways as well.

DGrant - I am the original poster. Yacht Controller is a competitor and they found the thread and are using a small snippet of what Andy wrote to disparage our product in their advertising.

Regarding what Andy wrote about the FCC, Yacht Controller is licensed for 433 Mhz and 868 Mhz, but they are using 433 Mhz and 916 Mhz, and so apparently they & the owners of their product are subject to FCC fines.

Additionally, they had serious interference problems when they were using a one-way, transmitter - receiver signal with a single band on 433 Mhz and so they added 916 Mhz.

They are now trying to convince the public that this is superior to our system which is a two-way, transmitter / transceiver - receiver signal that has 5 channel FHSS on 433 Mhz.

If that's the case, you might want to be careful where/how you derive information. If they're taking bits off of this type of site to promote their product, they will take it from anywhere.

You were the one that made the statement "getting it out to the boating public". You might be careful what public forum you use, as it's obvious any competitor can use it against you or anyone they choose. Someone got it "out to the boating public".

I have no dog in the fight, and it really has nothing to do with RC planes... but it's pretty easy to see someone(who ever it might be) has an agenda that's outside the realm of this site... and it's intended purpose. Why would someone go to an RC site to glean information like that?... Sure there are experts, and we know who they are pretty much, but what you did could be considered "baiting".. as what were you going to do with the information? Most likely the same thing your competitor did... maybe in a different fashion, but the intent was probably there.

I would say with as big as the internet is, there's got to be better forums to take your cause too. Albeit we have experts that frequent these forums, it's obviously not the best place to prove your point, and quite possibly backfired in a way you didn't anticipate. Doens't the "boating public" have any experts? If in fact your system is superior, your boat people would be able to discern that from their knowledge base. That stands to reason.

There's no need to try and explain your system or principles. I honestly don't care. I just found this thread inappropriate, and after seeing/reading how it was used(again I don't care who used it for what), I felt a need to comment. It's not appreciated when members of our RC community and their knowledge base are used to propagate issues, that are number one hidden agendas, and number two they aren't informed of how their comments could/would be used. One of our members comments were clearly taken out of context. You were the one that brought up the issue to begin with. It's best to not try and justify why. You will get nowhere. Maybe it's best to let this thread die, and hope the competitors customer base doesn't see it. Good luck with that.

DGrant, thanks for your valuable input, it is greatly appreciated!