- Joined
- Feb 3, 2012
- Messages
- 6,335
- Reaction score
- 5,523
Anyone out there tried the 3DR 915 MHz radio modules for telemetry? They claim a pretty decent range, better than an XBee Pro, and they're only about $40 a set.
3DR Radios for Telemetry
- Thread starter cerving
- Start date
Help Support The Rocketry Forum:
bobkrech
Well-Known Member
- Joined
- Jan 20, 2009
- Messages
- 8,352
- Reaction score
- 54
Read the specs carefully. Range is dependent on transmitter power, transmitter antenna gain, receiver antenna gain and sensitivity, and line-of-sight interferences, so be carefull to compare apples to apples. Antennna design is critical to range at these frequencies, and gain is dependent on design and directionality. The data rate is also range dependent: sending data at 200 kbps has a much shorter range than 10 kbps.
I suspect the commercial unit may perform better than the hobby unit, but it will also cost a little more.
Bob
I suspect the commercial unit may perform better than the hobby unit, but it will also cost a little more.
Bob
- Joined
- Feb 3, 2012
- Messages
- 6,335
- Reaction score
- 5,523
Good points Bob, but that's true of pretty much any radio unit. I'm looking for hands-on feedback.
I'm looking at 19.2kbps so there will be a higher SNR than there would be with, say, 115Kbps, and therefore more range. I did the same thing with a large outdoor 802.11 network deployment that we did; we took the data rate down to get a more reliable signal at larger distances. It made a huge difference. With the newer MIMO multipath units that probably wouldn't matter as much, but it sure helped a few years ago.
I'm looking at 19.2kbps so there will be a higher SNR than there would be with, say, 115Kbps, and therefore more range. I did the same thing with a large outdoor 802.11 network deployment that we did; we took the data rate down to get a more reliable signal at larger distances. It made a huge difference. With the newer MIMO multipath units that probably wouldn't matter as much, but it sure helped a few years ago.
mikec
Well-Known Member
- Joined
- May 9, 2009
- Messages
- 3,027
- Reaction score
- 838
There's been some discussion about how much range they really get -- see https://diydrones.com/forum/topics/the-real-specs-and-ranges-for-3dr-radios . FWIW, I've been happy with the XBee 900 Pro XSC, and there is a new version of that out for the same price (around $40 a module) that has twice the output power (stated range 9 miles dipole-to-dipole), lower current, etc, so I quit thinking about the 3DR.
I used them in my first tracker, but you know that. They worked just fine once they sunk up. One thing I like about them is their config qui is very straight forward and just works. The same cannot be said for digi's xbee gui, especially with remote config and firmware updates.
I wish they had a wire antenna version, but I guess it wouldn't be too hard to remove the sma and tack a wire on. The price is certainly nice.
I wish they had a wire antenna version, but I guess it wouldn't be too hard to remove the sma and tack a wire on. The price is certainly nice.
