Open Source Instruments Forum

Marco Leite writes, "PyEcog assumes that after the data start address, all data comes in packets of 4 bytes, with the Channel number appearing in the first byte. In the sample files that Kate sent me, this does not seem to be the case, for example, the byte value of 83, one of the tids recorded, appears most commonly at intervals of 36 and 42, the latter not being a multiple of 4. See below the histogram of intervals between bytes valued 83. Are the data packets now 6 bytes? How are they structured? How can we distinguish between NDF file formats? I couldn't find the relevant page in the OSI website with this information."

Dear Marco,

Documentation on this subject was inadequate. I have added a section on file formats to the main telemetry system manual, see here:

https://www.opensourceinstruments.com/Electronics/A3017/SCT.html#File%20Format

To summarize: the four-byte message core is accompanied by a number of "payload" bytes. The "payload length" is zero for the Data Receiver (A3018) and Octal Data Receiver (A3027). But for the Animal Location Tracker (A3038) the payload is sixteen bytes, and for the Telemetry Control Box (A3042) it is two bytes. As Kate Hills tells us in a separate e-mail, your recording comes from a TCB, so your conclusion that the record length is six bytes is exactly correct: four core bytes plus two payload bytes. The payload is: top antenna power and top antenna number.

Best Wishes, Kevan

PS. I hope you will register on this forum. You'll have to wait for me to activate your account. We had to enable "wait for administrator to approve activation" because we were being swamped by enthusiastic neuroscientists from Russian institutions who wanted to tell us all about their latest lifestyle-improving medical treatments.

Thanks Kevan! All clear and sorted