Range vs moto talk



I am not an engineer but I had plenty of them work for me and nearly 20 years in the Live TV business has put me at both end of transmitters/receivers of Video, Audio and Data. I am well versed in many forms of RF both digital and analog signals (even a little laser encoded data) everywhere from the side of active volcanos to sound stages buried underground.

I think the key thing here is that one digital signal on a similar frequency and even at the same power is not the same as another.

In the case of digital signals, encoding, compression, bandwidth consumed, error correction are all factors.

Handshakes are good things when they work and can also be a barrier to communication when something without a handshake might otherwise get through in part (assuming the encoding, compression and error correction can handle partial packets of information).

Also while not a factor in what you describe additional power can actually be a negative factor if it increases multipath and noise.

Simply put just because the Moto does get through is not an indictment of GoTenna’s methods.


@Posman, @Firqby and everyone else that contributed to this topic, thanks for the engaging and in-depth conversations. Seeing how passionate you are about our product is extremely rewarding to the team here at goTenna!

On to the issue at hand, I think we have a convincing answers to present. We analyzed the FCC report of the Motorola i335 phone, which can be found at this link: https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=Y&application_id=exRI7AR26L4TaEEdbdjA9w%3D%3D&fcc_id=IHDT56HG2

Transmit Power
Although the Motorola i335 nominal output power for the ISM transmitter (902-928 MHz, same as goTenna MESH) is stated at 890 mW, the effective peak power it transmits is actually 1 W as stated in Exhibit 6c “the modulation scheme employed can cause peak fluctuations in output power up to 0.5 dB from maximum pulse average power, which is 890 mW (29.5 dBm)” So the transmit power of the Motorola i335 is the same as goTenna MESH, at 1W.

Modulation Schemes
MSK, FSK, were mentioned as possible alternatives to the GFSK. Back during the architecture phase, we have weighted the pros and cons of these modulations schemes and have concluded GFSK is the best choice. Here is why, MSK (Minimum Shift Keying) effectively reduces the modulation index to 0.5, while improving spectral efficiency, the sensitivity will be degraded by 1.5 to 2.5 dB due to the compromised modulation index (rule of thumb ideal index is 1). FSK, although improves sensitivity, it creates high levels of spurious contents and side lobes, which causes regulation standard violations. The best of both worlds is the GFSK (Gaussian Frequency Shift Keying), it applies a Gaussian filter to the symbols before the frequency modulated signal to suppress the spurs and side lobes, at an expense of 0.5 dB reduced sensitivity.

So by the above data, goTenna MESH and Motorola i335 should have the same range performance, but it does not appear so, and we have a hypothesis - it has to do with the network protocol and the choice between optimizing a point to point system or a scalable mesh network.

Digging into the FCC report of the i335, we found that during transmission, the i335 floods the entire 902 to 928 MHz during a transmission by cycling and repeating through all 50 channels. i.e. Tx channel 1, then 2, then 3, to 50 and repeat. This is a simple but brute force approach to gain frequency diversity and continuous re-transmissions, which effectively improves range at expense of congesting the network. For a point to point, none shareable system, this is the right approach. However, for a scalable mesh network, this approach will cause significant issues - as the number of nodes scale, the overheads and complexity of the routing table scales exponentially, without allowing proper amount of time slots / quite time of nodes in the system, the defining meshing feature of goTenna will fail. So this is a compromise we are willing to make.

Of course, all of the above are concluded from paper studies. We can acquire a few of the Motorola radios and conduct measurements on them in our lab to confirm our hypothesis.

I hope this clears things up a little. Please let us know if you have any questions or found any mistakes in our analysis, and thanks again for being so passionate about our product!

JC and goTenna team


Hello, Jin_Gotenna! Your preliminary tests are very detailed. Also, thanks you for the modulation theory. I will be very grateful to Gotenna’s team if you do field tests and lab studies of mototalk in comparison with the Gotenna Mesh.


Plus, a wish for the product: given that there are not so many blending units in the world, I would be tempted to take into account the experience of point-to-point experience, since so far it is spread out!


That is a nice explanation. I’m going to show this to some of my Ameteur radio friends. There’s a lot to think about here. Some of our radios use a version of the protocol in those old Motorolas. I may also do some side by side testing since I have a couple of those old Moto phones. Once it warms up a little around here.


There might be something useful buried in those old Motos, but I suspect mostly not.

As JC noted, interesting the way Motorola went about this, but cell networks tend to operate much differently than mesh does. An approach that uses “brute force” works well for centralized networks, but the goTenna plays at the other end of that scale, where finesse and simplicity are advantages when there are only limited resources for/from any single unit, but the additive effects of meshing are what builds the overall effectiveness that users perceive.

While Motorola has fallen on hard times of late, it’s a pretty big outfit compared to goTenna. Gotenna, like most of us, has to play by the rules already set. Players as big as Motrorola, however, are big enough that gaming the rules or even rewriting them through lobbying, campaign contributions, etc is feasible. Kinda curious what was in that FCC report and if what Motorola did was later constrained/outdated by either new regulation or technical change.

Another factor is that even if there is some applicable tech in the Moto, you can’t forget that patents tend to apply to such things. Just because Motorola did something, goTenna can’t just “borrow” an idea without making arrangements to satisfy the patent holder. It might, but when things cost, then cost-benefit analysis has to be applied to determine whether that makes sense to incorporate into future goTenna technology.


Hello Everybody!

As noted by Jin_Gotenna, the floods in all spectrum ISM is perhaps a rough approach, but effective! and experience of Moto in direct talk is 15 years. Their radio DTR still cost decent money and have good reviews.

I’m sure that someone else’s experience is worth considering!


Certainly it’s worth considering the experiences other have. The technology of relatively low-powered radio makes it important to squeeze every possible advantage from the signal when you’re up against some pretty limiting regulatory and physical constraints.

Thing is it sounds a lot like Motorola was taking advantage of the power of a centralized network to game the most it could from the signals. A mesh network may seem superficially similar, but operates rather differently. Where there is some coincidence and possible advantage in looking to the Moto for possible solutions, it’s around the radio portion of the technology. Other than that, JC is making a notable point when he or she cautions about the differences in how the two networks operate in the third to the last paragraph of JC’s long note above.