New Toys!

[kbanks]

It's too soon for me to be quoting official release dates (we have to fully test these new products), but the following are all "real" in that I have actual running hardware in my possession:

ZIC2410_SE - we've had SNAP running on the CEL ZIC2410 chip since version 2.2, but now you can get that part in our SNAP Engine form factor.

AT128RFA1 - support for the ATMEL AT128RFA1 chip was added in version 2.3, but now you can also get a SNAP Engine built on this chip.

Si1000_SE - the first SNAP port to run on 900MHZ (versus 2.4 GHZ) hardware, this new SNAP Engine based on the Silicon Labs Si1000 chip will debut in the upcoming 2.4 release.

Details on these new SNAP Engines (including example scripts) will be in the upcoming 2.4 SNAP Reference Manual.

If you attended the ESC show April 26-29, you have already seen them in action there.

Two other (non-SNAP Engine) products have also been on customer wish lists for some time:

SNAPlink - need a "wireless UART", but don't want to make your own board (or use one of the existing "demo" boards)? Take a look at the new SNAPlink 232 and SNAPlink 485 boxes.

SNAPconnect E10 - need to connect your SNAP nodes to the Internet, but don't want to put a PC at your remote site? Take a look at the new SNAPconnect E10, an embedded computer in our "SNAPlink" form factor.

I almost forgot - there is also a new smaller form-factor SNAPstick. Instead of accepting plug-in RFEs and SNAP Engines, it has a chipset built-in. This lets it "fit" next to other USB devices.

My point in posting all of this is that many of you are evaluating SNAP products for your custom applications, and you need to be aware what all there is to choose from.

[John_Dailey]

We're very excited about the forthcoming smaller form factor SNAPstick, as we have an immediate use for it. Will it support both the higher and lower powered radios?

[Pflibsep]

What approximate bandwidth are you guys looking at in the 900Mhz module? The main reason I want to use that module is the increased range it has. 2.4Ghz doesn't do anywhere close to the 3 miles claimed in the documentation, unless you were in space or something. It's more like 1/4 mile.

[wadepat]

SNAP Stick supports both amplified and unamplified radios. It also supports both 250 kbps and 2 Mbps bandwidths.

RFET ranges are 3 miles open field and were tested to that range at 4 feet off the ground with normal SMA antenna's. If you are not open field in your test then the distances drop off depending on what is in the signal path. For instance, 2 indoor walls cut the distance in half. 4 indoor walls cut it to 1/4.
An F antenna in proper orientation on an RFET open field will go 2.5 miles.

If you are using an RFE (no transmit amp) or if using an F antenna in its worst
orientation, then you will get much less than 3 miles open field. RFE is 18 dBm less than an RFET in transmit power and an F antenna in poor orientation can cut another 10 dBm as well. (Every 6 dBm cuts distance in half.)

900 MHz is an Si1000 256 kbps radio with a very good link budget for distance and external SMA antenna capability. 900 MHz still drops off due to walls and so forth, but it typically drops off less.

[Pflibsep]

I did all my testing in open field with the amplified F-stlye antenna. However I did not specificially test individual angles of the antenna which could have effected it. However I did do the calculations of the budget link quality. At three miles I believe it was around -109 dbm which is just above the radio threshold (receiver sensativity), which would imply that the figure posted in your datasheet was based on that. What angle was the SNAP modules? We they perpandicular to the ground and parallel to eachother? Does that antenna circularly polarize the wave?

[wadepat]

F antenna's are not quite as good as SMA antenna's but they are close when at the correct orientation. The best F orientation is with the "F" standing on its head so the "bottom" of the F is pointing skyward. That is also the best orientation for the receiving antenna.

The F radiation pattern is a toroid (donut) perpendicular with the antenna in the center. In addition, the range when it is one foot off the ground is about a 20% reduction compared to 4 feet off the ground. It continually increases distance as it gets farther and farther off the ground.

So,... you need to ensure you have sufficient link budget for all of these factors as well as for things in the signal path so that worst case you get connection. Of course if there is another node in between, then meshing will help solve this for you as well. Also, there are SMA antenna's that supply gain which can give you an extra 50% in range. Look for 3 dBm SMA antenna's if you want to try them with SMA RF Engines.

[Pflibsep]

All my tests we done at approximately 4 feet off the ground. The orientation was exactly as you said. Where did you folks test? I would be surprised if the signal made it more than a couple hundred feet in doors...let alone 1/4 mile.

[Pflibsep]

Unfortunately it appears that the SMA antennas perform only about 10% better due to their 3dbi gain. The ranges mentioned here are all at the "critical point" where connections are starting to consistently drop off. All distances were measured with GPS positioning at each node in real time.

[wadepat]

The 3 mile range is line of sight which is a common way to give people ideas of radio distance. It was measured on a flat stretch of road at 4 feet height. There is no way to tell what indoor distance will be except "typically". The reason is that "indoors" is indeterminate. For instance, dry-wall walls degrade 2.4 GHz by about 3 dBm. Concrete walls can degrade 10 dBm. Metal doors degrade differently than wooden doors and so forth. So what you may see as an "indoor" distance is different than someone else will see with a different "indoor" scenario.

[Pflibsep]

Yea you're right. I observed something pretty close to that. A human interferes by about 8 dbm. All my observations were taken outdoors as well. How did you measure that you had a connection? were you using two nodes with no computer/portal? I have a feeling that the laptop I used having a metal body caused an unfortunate amount of interference. Should I use the SNAP stick on the end of a USB extender cable so it's away from the "noisy" computer? I probably should have disabled my computers wireless card as well to ensure it wasn't interfering as well.

[korda]

Question to "widepat":

The best F orientation is with the "F" standing on its head so the "bottom" of the F is pointing skyward.

Can you provide graphical or web-link example of F antenna best orientation?
The "bottom" of the F can be interpreted wrong way.
Are you sure about this orientation?
I have heard before that the best F antenna orientation is laying on its side, so its 90 deg rotation, but you are talking 180 deg turn.
The best answer would be an image of RFE oriented correctly.
Thank you.

[wadepat]

Here is a simple drawing of the proper F antenna orientation and how the antenna pattern looks. The F antenna is easily visible on an RF Engine so it
should be straightforward to see which way to orient it.