OK, so I did a bit more research.
The Pelagic Systems used by a lot of different computers - FCC ID MH8A operates at 38kHz modulation not stated.
The latest Suunto 2014 - FCC ID RYP21162 operates at 123kHz with PSK modulation.
I did my tests with an older Suunto which I think dated around...
I guess they had some kind of identifier or maybe just signal strength. You had to hold the computer next to the transmitter to get it to start working (a bit like the early heart monitors from Polar), it was all a bit problematical because sometimes it would just refuse to work.
Hi, I listened to the audio. I notice the period of the pulses did not change so I would guess the pressure is encoded in the signal together with the identity of the transmitter. I agree it will probably be FSK modulation.
The transmitter I tested with, was an early one with no identity, it...
Some years ago I was having a problem with my Suunto Vytec and transmitter so decide to investigate. I made a simple resonant circuit using a ferrite rod antenna from a wireless clock (one that picks up the LF signal with time information) with a two transistor amplifier. It worked very well...
Thanks for that. I contacted Aqualung and they still have some black exhaust covers so I ordered from them. I also contacted Genesis who replied they might have some if I sent a photo but it proved unnecessary.
I don't use the phone app very much(I prefer the desktop) but the other day wanted to find a specific dive (I was not at home) and notice that somehow the display has changed. Instead of one line for each dive I now seem to have half a screen of information including the graph for each dive...
I did my first 200 dives with a Siebe Gorman Mistral in the 60's. It is a very simple single stage regulator. You can buy a set of BA (British Association) taps and dies on the Internet and make any screws you might need for restoration.
Way back in May 2017 the BSAC recommended limiting gas density to 6.2gm/l and PN2 switches to 0.5-0.7 bar.
Having looked at the recently published gas density tables it doesn't seem much has changed since May 2017.
It seems to me that Termo Industria in Italy just about manufactures every SPG on the planet. They make the gauges for all the major Scuba equipment brands.
Does anyone know of another manufacturer?