JRAM suitability - Seismometers not on the list

Hi, I’m a newbie here, please excuse my ignorance but the only stupid questions are the ones that are never asked. I want to use a RJAM with a Kinemetrics WR-1 Ranger (0.05 to 20Hz) and another RJAM with three Sprengnether Long Period Seismometers, one vertical & two horizontals recovered from the WWSSN. Is there anyone within the community that has some experience with either of these instruments and RJAM, or any reason why they may be incompatible. These items are not included in the “suitability list” for the RJAM, perhaps there is a good reason for it? I have manuals for the seismometers, if that helps.
My intention is to send data to a local server in miniSEED format for data distribution.
Thanks for your assistance.

Is this the same as an SS-1 Ranger? We have experience with those.

We just do not have them to play with here in the office.

Sure, we can evaluate them. But we charge per hour for this service. Please message me directly for a


Hi Branden,
The Ranger WR-1 is an active, single axis device with a maximum output of +/-2.5V. It has about half the sensitivity of the SS-1 (160V/m/s) but is not tuned around 1Hz like the SS-1. I was hoping that there might be someone out there currently operating one with the RJAM and able to provide some feedback on it’s operation as a system.
Thanks Peter

I’d try using components for the 10V differential output. So R[a] are 4.99K and R[b] are 2.2k.

Your +/-2.5 volts means a voltage swing of 5 volts–2.5 positive and 2.5 negative. With differential voltage this is doubled to 10 volts.


Thanks for the tip Bob. I have not yet ordered the RJAM but should be able to do so soon. As this is a fairly new product, I have not found an independent source of feedback on it’s performance yet.

I’ve been in contact with Dave Nelson in California who uses four
JAM’s in his seismic vault. He told me the JAM is the best ADC on the
market for the price. His vault contains a number of professional and
very expensive seismometers.

Dave is a retired aerospace engineer who was responsible for design of
the FMES and Yuma seismometers. The Yuma is a force balance
teleseismic sensor for amateur construction with performance matching
professional units.

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Hi Bob,
I have found that CERI, Uni of Memphis is implementing the RJAM on their Southern Appalachian Seismic Network, replacing NI digitisers. They have a couple of broadband seismometers deployed at Fort Payne, Sewanee and Cooper Creek but don’t seem to ‘advertise’ what they actually are (understandably I suppose) along with a bunch of short period instruments as well. I am thinking of contacting the professor responsible for the upgrade (name withheld) but I’m not sure about that. Perhaps he is on this forum.
Thanks for the info on Mr Nelson, I will search for some details online. I should probably point out that I am located in Australia, I am not trying to find and pinch anyone’s hardware.
Thanks Peter

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