Hi Alex, Great news! A GroupGets campaign for GPS board only would be much appreciated so we can add the functionality to the Audiomoth's already in place. There is ample of time now for preparing next season here in the Netherlands. I would much rather use the boards coming from Open Acoustic Devices off course, the combination with Audiomoth being central to the design and the support through this forum being outstanding, really. Thanks for the tech-details anyway. Cheers, Eric

Hi Alex, This is not more that a first impression but I am very positive about it as well. I realized i could improve by adjusting for time-drift per instrument and the difference in sample-rate connected to that. However the drift as shown in the (very handy) GPS logfile was comparable for the three devices although not exactly the same off course. The distances in the case of Bittern are much greater that what they would be in the case of (e.g.) songbirds on a smaller patch and therefor the relative error is smaller and the booming area of interest larger which makes the whole effort easier . I am quite certain that for next season there will be a grit of synchronized Audiomoth's in operation here over a considerable (N2000) area of interest which will be of real conversational importance i reckon. Greetings, Eric

Hi Alex, No i just used the times measured as such (for Bittern i use the time of peakfrequncy which is determined by Ravenpro, since this is so well defined in this species and this probably is not affected by the traveling of the sound over distance so the error of (human) measuring is minimized), i did use multiple short recording periods so the GPS synchronization moment was never far from my actual recordings. We are still in the progress of finishing our program so hat it will give us coordinates as a result of the estimate bases on entering the coordinates of AM's plus time measurements for each recorder. For this test i used a visual approach that i can email to you if you wish. Cheers, Eric

Hi Everyone, I have my first results on localizing Great Bitterns. The test was done in an area where i know the exact location of booming-posts. I used a triangle of the Audiomoth/GPS combinations placed about 400 meters apart. Measuring the exact time of arrival on the spectograms and a program of our own making gave me three hyperbole's crossing where the sound should come from. The results are as good as spot on! For one bird, that booms on a distance of about 2 km's from the center of my triangle the estimate of its location was perfect in terms of direction, the exact distance is (logically) more difficult to establish in such a case. Greetings, Eric

Hello Team, Andy, That is very good news! Thanks for the effort you put into this most valuable extension. For my plan of testing the Time-Of-Arrival-positioning of Bitterns that would be well within the deadline. If i could start say the the first half of March all would go according to plan. If it would be helpful me doing some more (field) testing earlier before the season we could contact about using the prototypes, i will reply to your email-address Andy so you will have mine as well. Cheers, Eric

Hi Alex, Is there a chance that the GPS modules will be available before the start of this years breeding season? @David Jarrett, i have send you an email with a link to a page where you can experiment with triangulation, did that arrive? Anyway I am working on an alternative method for synchronization and will post the results here if these would be worthwhile. Kind regards all, Eric

Hi David, Its an established method that we worked out in a little test program. In essence it gives you a crossing point of three hyperboles as an estimate of the possition of a soundsource. If you take two audiomoths that are propperly synchronize and place them some distance apart you can calculate a line on which the source must be given a measured time-difference of arrival of its sound at each audiomoth. Than if you place three audiomoths in a triangle you can calculate three hyperboles that will cross each other and so gives you an estimate of the position of a soundsource. I plan to do a fieldtest in the next months. If you wish we could share information on this, no problem. Cheers, Eric

Hi Alex, That really is great news! Count me in for a group purchase, if that is possible that is. There will be an anouncement of this i expect and will look for it every day! This level of synchronisation would certainly do it for localisation of Bitterns. Can't wait for next season. Many thanks, Eric

Hello, any news on the status of this GPS synchronisation solution? I did a very succesfull project on Bitterns using Audiomoths and already collected a ton of useful data (thanks for making this open source project happening! It realy made a difference). If i could get the timekeeping accurate for next season it would be straightforward to add sufficiently accurate localisation of the booming males. Programming and math to do this allready in place so hopefully I will find a solution to sufficiently synchronize the 8 Audiomoths. One sulution would be to measure the drift for every particular divice and use a correction when analyzing. Another is to make a simple device that produces a accurately timed beep and put this 'on tape' when i place a Audiomoth in the field and again when i collect it. Any other suggestions maybe. Cheers, Eric