Are Pressure Transmitters compatible across brands?

[tursiops]

I have read that the Halcyon transmitters are MH8A-compatible, but have not had the chans to test myself.

Definitely not. Different frequency (125 kHz vs 38 kHz of the MH8A), different signal protocol (e.g., error-checking). Electronics have progressed in 30 years, but the physics are the same.

 

[martinot]

Definitely not. Different frequency (125 kHz vs 38 kHz of the MH8A),

I see. Thanks!

different signal protocol (e.g., error-checking).

What is new different, and what +/- with the new protocols?

 

[tursiops]

What is new different, and what +/- with the new protocols?

Revolutionizing UW Wireless Communication

Arne Sieber and Jarrod Jablonski unveil the Halcyon SYMBIOS Ecosystem—a magnetic-induction, dual-axis wireless platform that frees rebreather data from cables and flaky acoustics. By pairing high-speed induction coils with redundant processors and orientation-agnostic antennas, SYMBIOS pushes...

indepthmag.com

Read with some skepticism. It says things like how it uses "magnetic field-based data transmission" which is not a big deal; that is effectively what the MH8A uses. The article also says one of the advantages is, "are not absorbed by water like RF waves" which is balderdash; firstly, their 125kHz signal IS RF, which only means Radio Frequency, it is just Extremely Low Frequency (ELF) like the MH8A 38kHZ which, secondly, is why it has low absorption in water (BT and WiFi can only go cm underwater).
The article says, in answer to your question [my comments are in square brackets, in italics]

Data Transfer and Efficiency: 10x Faster​

While older magnetic systems operate at 5–40 kHz [such as MH8A] and deliver data rates of 200 to 1,000 bits per second, the SYMBIOS CCR transmits at 125 kHz, achieving a data rate of up to 10,000 bits per second (10 kbit/s).​

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This higher frequency [125kHz versus 38kHz] allows:​

• Shorter data packets (e.g., a 5 ms transmission for critical tank pressure)
• Lower probability of data collision even in multi-transmitter environments
• High-resolution, high-frequency updates essential for real-time PO₂ management and system health monitoring

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Crucially, the system includes an integrated checksum and error correction algorithm, which not only detects corrupted transmissions but, in many cases, can recover and correct the data on the fly— a feature rare in other magnetic or digital underwater systems. [this is made possible advances in cheips and processing power...hence my comment about electronics advancing over the last 30 years]​

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The article goes on to explain that they do not send all the data in each transmission; some things ae sent more often, some thing only now and then. This is more efficient but has only been possible with modern encoding schemes and processors/chips.

The table at the end of their article summarizes their systems against the MH8A. but even this table needs some skepticism. For example, the MH8A does NOT have "frequent data collisions" as stated. Occasional and rarely critical" would be more accurate.

So the article is a bit of a sales job, but does have some good info in it.