Gotenna? - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: July 22, 2018, 03:35:27 pm
content: https://www.gotenna.com/What do you think? It seems to be a mesh network addon for your phone or laptop that uses 150MHz or so.I kind of wonder how easily you can hack it to work on other frequencies(legal issues aside, I don't really care to get into discussion about the spirit of the law, interference ,etc. just electronics discussion if/when it comes to any sort of circuit modding)

author: chris_leyson
author_rank: Super Contributor
timestamp: July 22, 2018, 04:13:13 pm
content: Found this on the website.On which frequencies does goTenna Mesh operate?The first-gen goTenna works on the 151-154MHz band (MURS), whereas goTenna Mesh will transmit at 1 W on 902-928 MHz in the United States, and will vary throughout other countries. For example: goTenna Mesh will transmit at 0.5 W on 869.4-869.65 MHz in Europe and other CE countries, and the device will auto-tune itself to the appropriate frequency band and power output based on the location where it's being used.

author: xaxaxa
author_rank: Regular Contributor
timestamp: July 22, 2018, 04:55:18 pm
content: There was another kickstarter (sonnet I think it's called) for something very similar that uses lora; not sure if the newest gotenna also uses lora but it seems likely.I don't think there is any point modding these as you can build something with better specs for far cheaper; for example ax5043 + acpm-7868 + stm32:

author: CopperCone
author_rank: Super Contributor
timestamp: July 22, 2018, 05:01:09 pm
content: I meant to use their app/software.

author: curiousmuch
author_rank: Newbie
timestamp: August 07, 2018, 11:19:10 pm
content: Quote from: xaxaxa on July 22, 2018, 04:55:18 pmHello xaxaxa,Did you develop the USB stick attached? I've been exploring developing a similar board for APRS. The AX5043 is unique as it supports AFSK and narrowband digital formats.

author: xaxaxa
author_rank: Regular Contributor
timestamp: August 08, 2018, 11:11:31 am
content: Quote from: curiousmuch on August 07, 2018, 11:19:10 pmHi, yes I designed that as a general purpose "transceiver + mcu" thing, for things like remote sensor nodes and mesh network nodes. I can publish the schematic and layout if you are interested. It is a 4 layer design and contains: SAW filter, LNA, power amplifier (up to 3W), tx/rx switch, stm32f103, and lithium battery protection. I selected the ax5043 because it has the highest sensitivity at a given bitrate compared to other single chip transceivers (and is on par with lora when in BPSK mode with FEC).

author: curiousmuch
author_rank: Newbie
timestamp: August 08, 2018, 05:58:46 pm
content: That would be awesome! I'd love to look at it if you're willing. I'm still on the edge about settling with the AX5043 as I believe it's been marked EOL:https://onsemi.secure.force.com/PCN/?pn=AX5043The CC1200 (basically CC1120 with the required 139MHz band) is the other option as it supports a similar mode (CFM). Do you have an opinion of the CC1120?QuoteAnd narrowband doesn't suffer from the same collision issues as LoRa.

author: xaxaxa
author_rank: Regular Contributor
timestamp: August 09, 2018, 07:24:50 am
content: I've actually originally planned to use the cc1200, but only ended up using the ax5043 because it has better sensitivity (by about 4-8dB depending on modulation and FEC) and is cheaper; however the cc1200 can go up to 1Mb/s whereas ax5043 is limited to about 100kb/s (50kb/s with FEC). The ON semi website seems to show AX5043-1-TA05 as EOL but AX5043-1-TW30 as active; I think they are just changing packaging.I've uploaded the pcb files and example code here:https://drive.google.com/drive/folders/1UPyOt2nwJQLfSlKE5E5JedGvO2yZQdQ4?usp=sharingThe pcb and schematic files can be opened with geda pcb and gschem.To build the code you need to edit Makefile and put in the path to libopencm3.There also seems to be a library for it here:https://github.com/richardeoin/ax/tree/master/sw

author: curiousmuch
author_rank: Newbie
timestamp: August 09, 2018, 09:01:14 pm
content: Thank you so much! I'll make sure to send you a message when I finish my schematic / design.